Diagnostic Accuracy of 1H-MRS in Detecting the Oncometabolite 2-Hydroxyglutarate (2HG) in Adult-Type Diffuse Gliomas

Diagnostic Accuracy of 1H-MRS in Detecting the Oncometabolite 2-Hydroxyglutarate (2HG) in Adult-Type Diffuse Gliomas | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Diagnostic Accuracy of 1H-MRS in Detecting the Oncometabolite 2-Hydroxyglutarate (2HG) in Adult-Type Diffuse Gliomas Anna Hebda, Pawel Wawrzyniak, Sylwia Heinze, Patrycja Mazgaj, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9266342/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract Purpose To evaluate the diagnostic accuracy of three proton magnetic resonance spectroscopy (1H-MRS) strategies—short echo (TE 30 ms), intermediate echo (TE 97 ms), and MEGA-PRESS—for detecting the oncometabolite 2-hydroxyglutarate (2HG) to non-invasively determine isocitrate dehydrogenase (IDH) mutation status in adult-type diffuse gliomas. Methods A cohort of 152 patients with adult-type diffuse gliomas (84 IDH-mutant, 68 IDH-wild-type) underwent preoperative 3T MRI incorporating standard morphological sequences and 1H-MRS acquisitions. Spectra were evaluated to assess the presence of a 2HG peak. Diagnostic performance was analysed independently for each method and collectively for a subgroup of patients receiving all three sequences. Results The intermediate echo (TE 97 ms) method demonstrated 100% specificity and 51.2% sensitivity, while the short echo (TE 30 ms) sequence achieved 97% specificity and 88.9% sensitivity. The MEGA-PRESS method yielded 86.7% specificity and 72.2% sensitivity but was limited by a high non-diagnostic rate (17.5%) due to artifact susceptibility. When combined, the spectroscopy methods achieved 100% sensitivity, 85.7% specificity, and 93.7% overall accuracy in detecting 2HG. Conclusion Conventional PRESS sequences (TE 30 ms and TE 97 ms) outperform MEGA-PRESS for the routine clinical detection of 2HG due to higher technical reliability. An optimized conventional PRESS protocol offers a robust, highly accurate, and non-invasive preoperative tool for identifying glioma genotypes and predicting tumor phenotypes. 1H-MRS 2-hydroxyglutarate IDH mutation diffuse glioma radiogenomics neuro-oncology Figures Figure 1 Figure 2 Figure 3 Introduction In the 2021 World Health Organization (WHO) classification of Central Nervous System (CNS) tumours, molecular diagnostics have assumed a significant role in the categorization and management of gliomas [ 1 , 2 ]. Among the key molecular markers, the isocitrate dehydrogenase (IDH) mutation status is one of the most important prognostic and diagnostic biomarkers, especially in adult-type diffuse gliomas. IDH mutations result in the accumulation (in the cytoplasm of glioma cells with IDH1 mutation and in the mitochondria of cells with IDH2 mutation) of the oncometabolite 2-hydroxyglutarate (2HG) within tumour tissue, providing a critical molecular signature for diagnosis and further prognosis [ 3 – 5 ]. Despite histopathological analysis remaining the gold standard, the non-invasive detection of IDH mutation status is important for prognostication and therapeutic decision-making. Nowadays, radiogenomics is an evolving field of study that utilises advances in image acquisition and analysis to correlate imaging features with molecular markers of diseases. It focuses on the relationship between genomics and imaging phenotypes, and has been widely applied to address tumour heterogeneity and predict immune responsiveness and progression [ 6 ]. Preoperative non-invasive methods for verifying mutation status could greatly influence patient management, especially when considering the risks associated with biopsy in eloquent brain areas or in differentiating gliomas. The development of a protocol including 1H-MRS spectroscopy focused on the detection of 2HG will enable the non-invasive determination of IDH [ 3 , 7 – 11 ]. This study investigates the effectiveness of 1H-MRS in detecting 2-hydroxyglutarate (2HG) in brain tumours, specifically in adult-type diffuse gliomas. We implemented three 1H-MRS strategies to check how effective these spectroscopy methods are in detecting 2HG. We used a short echo time (TE 30 ms) sequence, an intermediate echo time (TE 97 ms) PRESS sequence, and the MEGA-PRESS method to improve non-invasive diagnostic methods. Materials and Methods A total of 152 adult-type diffuse glioma patients treated between January 2020 and October 2025 were included in the analysis. All patients underwent preoperative multiparametric magnetic resonance imaging prior to planned surgery or biopsy, and had available histopathological and genetic test results. The protocol included standard morphological sequences and optimized spectroscopy 1H-MRS providing detection of the oncometabolite 2HG. Clinical data, tumour characteristics, and genetic markers such as IDH1 mutation, MGMT promoter methylation, TERT pathogenic variant, and the appearance of microvascular proliferation and/or foci of necrosis were collected. In this study, we focused on the evaluation of IDH1 mutation status. IDH2 mutations were not considered in our analysis, as IDH2 status was not evaluated in a subset of the included cases. Three spectroscopic methods were employed to assess lesion IDH mutation status by 2HG detection. For solid-appearing lesions, spectra were obtained from the centre. In contrast-enhancing lesions, spectra were acquired from the enhancing part unless an explicit necrotic core was present in the lesion centre, which was avoided in voxel volume. During each examination, basic long (135 ms) and short (30 ms) echo time spectra were acquired from the lesion and normal-appearing brain tissue, in addition to MEGA-PRESS and TE 97 ms acquisitions from the lesion. Intermediate (97 ms) Echo Time Spectra The first method was the intermediate echo time (TE) PRESS (Point RESolved Spectroscopy) sequence with TE 97 ms. This specific TE was chosen to minimize the contribution of other overlapping metabolites (GABA, glutamate, and glutamine) for 2HG detection [ 3 ]. The sequence consisted of 160 averages with a repetition time (TR) of 2000 ms. Voxels were cuboids 20x20x20 mm or bigger, so the minimal volume was 8 cm³. In the case of smaller lesions where the prescribed voxel was bigger than the lesion, partial volume effects were accepted. An automatic shimming procedure was performed unless it produced poor homogeneity, in which case manual adjustments were performed. Short (30 ms) Echo Time Spectra This method is based on standard TE 30 ms voxels acquired during routine MRS examinations [ 12 ]. Information about 2HG is derived during post-processing. Two Gauss peaks are fitted into data from the lesion and normal-appearing brain tissue. These peaks are Glx3 with 2HG at 2.25–2.35 ppm and Glx4 at 2.31–2.40 ppm. The reasoning behind this method is that 2HG contributes to the overall integral of Glx3 in the lesion compared to that in the reference voxel, and it does not contribute to the Glx4 peak. Comparing integrals of these fitted peaks follows simple math: Positive values indicate the presence of the 2HG peak and negative values deny it. Acquisition employs a standard PRESS sequence with 80 averages and a TR of 2000 ms. Voxel sizes vary significantly to avoid partial volume effects. Similarly to TE 97 ms acquisition, an automatic shim procedure was used with manual adjustments if needed. MEGA-PRESS Acquisition The third method was MEGA-PRESS (Mescher Garwood Point Resolved Spectroscopy), which uses spectra editing pulses to null metabolites overlapping with 2HG [ 13 ]. MEGA-PRESS consists of two separate acquisitions: one with editing pulses and another without it. The difference spectra is then calculated, leaving only metabolites that got disturbed by the editing pulse. The sequence is originally aimed at quantifying GABA, but since 2HG has similar protons resonating at 1.9 ppm (sensitive to editing pulses), it is present in the difference spectra. Three spectra were obtained from every lesion: water-suppressed MEGA-PRESS, one without water suppression for eddy current correction, and a TE 30 ms PRESS spectra for internal water peak reference. Water-suppressed acquisition consisted of 96 averages (two sets of 48 averages) with a TE of 68 ms. Unsuppressed acquisition had 16 (two sets of 8) averages, and water reference TE 30 ms had 16 averages. In all cases, a TR of 2000 ms was used. Voxel sizes for MEGA-PRESS followed a similar pattern to TE 97 ms. Automatic shim followed by manual adjustment, if needed, was performed. TE 97 ms and MEGA-PRESS were analyzed by LCModel software with simulated basis sets. All simulations were performed by FID-A in the MATLAB environment. The MEGA-PRESS basis set contained these metabolites: NAA, NAAG, Lac, GSH, Glu, Gln, GABA, and 2HG. The TE 97 ms basis set contained: Ala, Asp, Cr, PCr, GABA, Glc, Gln, Glu, GPC, GSH, 2HG, Ins, Lac, NAA, NAAG. Spectra were fitted and the Cramer-Rao Lower Bound (CRLB) was assessed to determine whether the 2HG peak was present or not. Gauss fits for Glx3 and Glx4 peaks were added to the automated post-processing pipeline of the MR Spectroscopy application on syngo.via software (Siemens, Erlangen Germany). Peak integrals were used in calculations. Two phantoms containing brain metabolites in nominal concentrations were used for testing. One phantom had 2HG. These acquisitions were tested on such phantoms using the above parameters. Statistical analysis was performed on data achieved for the detection of the 2HG oncometabolite in both tumour samples and reference spectra obtained during examinations performed on patients and dedicated phantoms. The correlation of 2HG occurrence with molecular diagnosis and the determination of accuracy, sensitivity, and specificity for the validated method were verified. Results A total of 152 patients with adult-type diffuse gliomas underwent proton MR spectroscopy as part of a 3T MRI examination protocol extended with single-voxel PRESS and MEGA-PRESS acquisitions for the non-invasive detection of 2-hydroxyglutarate (2HG). The study cohort comprised 69 women and 83 men, with a mean age of 46 ± 13 years. IDH mutation status was available for all patients: 84/152 (55%) were IDH-mutant [IDH(+)] and 68/152 (45%) were IDH-wild-type [IDH(-)]. The analysed group comprised 54 out of 152 (36%) WHO G2 tumours, 26 out of 152 (17%) were G3 tumours, and the remaining 72 out of 152 (47%) were wild-type G4 tumours. The analysed group comprised 66 cases of IDH1-mutant astrocytoma (43 G2, 19 G3, 4 G4), 18 cases of IDH1-mutant oligodendroglioma with 1p/19q codeletion (11 for G2, 7 for G3), and the remaining 68 cases were G4 wild-type, of which 32 were histopathological glioblastomas with necrosis and proliferation of small vessels, whilst the remaining 34 were wild-type astrocytomas. Most patients exhibited high-grade features in histopathological evaluation with MVP and necrosis for G4 tumors, including prominent microvascular proliferation (MVP). Furthermore, nearly half of the G4 cases had TERT promoter mutations, the assessment of which has recently become a standard component of molecular diagnostics. In some patients, necrosis within tumors classified as molecular glioblastomas (molecular GBM) caused underscoring of the histopathological and molecular heterogeneity of these lesions. The number of MR spectroscopies performed using individual methods, specifying the number of non-diagnostic spectra, is presented in Table 1 . Achieving consistently high-quality MEGA-PRESS spectra proved challenging, which ultimately compromised the sensitivity of the method. Table 1 The amount of 1H-MRS performed using individual methods. 1H-MRS All spectra Non-diagnostic spectra Diagnostic spectra 97ms 152 0 152 MEGA-PRESS 80 14 (17,5%) 66 30ms 150 3 (2%) 147 Data analysis was performed using two complementary approaches. First, each spectroscopy method (PRESS TE 97 ms, PRESS TE 30 ms, MEGA-PRESS) was evaluated independently, reflecting differences in group sizes related to the later introduction of MEGA-PRESS into the clinical protocol. Second, diagnostic performance was analyzed in the subgroup of patients who underwent all three spectroscopy techniques. Intermediate-Echo PRESS (TE = 97 ms) A total of 152 patients had diagnostic-quality spectra acquired with TE 97 ms. The 2HG peak was identified in 43/84 IDH(+) cases (51.2%), whereas all IDH(-) cases showed no detectable 2HG. In the Intermediate-Echo PRESS method, none of the wild-type tumours exhibited a 2HG peak. The upper limit of significance was set at 50% SD of the fit based on the CRLB (Cramér-Rao Lower Bound) of 2HG in the spectrum analysed using LCModel. Above this value, it was assumed that the estimation uncertainty was too high and, therefore, that there was no contribution of 2HG to the spectrum. Based on these results, the diagnostic sensitivity of TE 97 ms PRESS was 51.2%, with a specificity of 100% and an overall accuracy of 73.0%. The positive and negative predictive values (PPV and NPV) were 100% and 62.4%, respectively. Short-Echo PRESS (TE = 30 ms) Short-echo PRESS spectra were acquired in 150 patients; 3 spectra were of low quality, so analysis was performed for 147 patients. For this method, the most important factor is the quality of the spectrum obtained, meaning whether we are able to distinguish the peak in the Glx slope at approximately 2.25 ppm and approximately 2.35 ppm, assigning them to Glx3 and Glx4, respectively. In two patients, analysis was not possible—one patient had an additional high peak at 2.38 ppm, distorting the spectrum for Glx4; in another patient, the Glx slope was almost a straight line with no distinct peaks. A detectable 2HG oncometabolite peak was observed in 74 patients. The calculated ratio of Glx3 to Glx4 yielded the following median values: for IDH(-) and no 2HG visualized it was 0.48; for IDH(+) with the presence of 2HG confirmed in the spectrum, the median value was 1.38. For all reference spectra, the median Glx3/Glx4 was 0.91. We set the threshold for the occurrence of the 2HG peak as positive values (> 0%) in the equation. 72/81 IDH(+) patients (88.9%), while 64/66 IDH(-) patients (97.0%) demonstrated no measurable 2HG. The resulting diagnostic sensitivity was 88.9%, with a specificity of 97.0% and an overall accuracy of 92.5%. The PPV and NPV were 97.3% and 87.7%, respectively. MEGA-PRESS Acquisition Analysis MEGA-PRESS 2HG-edited spectroscopy was performed in 80 patients; however, 14/80 spectra (17.5%) were non-diagnostic, leaving 66 spectra suitable for interpretation. The number of spectra analysed for this method is lower than for the other methods due to the shorter period of time during which exams using this sequence were performed. As in the TE 97 ms method, we set a value of 50% SD of the fit as the significance threshold for the occurrence of 2HG in the spectrum. Among evaluable cases, the 2HG signal was detected in 26/36 IDH(+) patients (72.2%), while no 2HG was found in 26/30 IDH(-) patients (86.7%). The calculated sensitivity, specificity, and accuracy for MEGA-PRESS were 72.2%, 86.7%, and 78.8%, respectively. The PPV was 86.7% and the NPV was 72.2%. Although MEGA-PRESS demonstrated unique spectral editing capabilities, it also showed the highest proportion of non-diagnostic examinations (17.5%). This elevated failure rate highlights the susceptibility of the edited sequence to artefacts and technical limitations not observed to the same extent in conventional PRESS acquisitions. A comparison of the three used 1H-MRS methods is presented in Table 2 . Table 2 Comparison of the spectroscopy methods used in the study. 1H-MRS all spectra diagnostic spectra sensitivity [%] specificity [%] PPV [%] NPV [%] ACC [%] 97 ms 152 152 51,2 100 100 62,4 73,0 30 ms 150 147 88,9 97,0 97,3 87,7 92,5 MEGA-PRESS 80 66 72,2 86,7 86,7 72,2 78,8 PPV – positive predictive values; NPV – negative predictive values; ACC – accuracy Combined Analysis of Three 1H-MRS Methods In the combined analysis of all three MR spectroscopy–based methods (in 63 patients three diagnostic spectroscopic methods were obtained in a single examination), the presence of the oncometabolite 2HG was detected in a substantial proportion of IDH-mutant gliomas. Specifically, a 2HG peak was identifiable in at least one method in all 35/63 IDH-positive cases, whereas unexpected 2HG positivity was observed in 4 (2 GBM and 2 astrocytomas) out of 28/63 wildtype lesions. Overall diagnostic performance for detecting a 2HG peak using any of the three approaches is summarized in Table 3 . When considering all positive detections, the combined methods achieved a sensitivity of 100%, specificity of 85.7%, positive predictive value of 89.7%, negative predictive value of 100%, and an overall accuracy of 93.7%. Table 3 Combined analysis of all three MR spectroscopy–based methods (2HG peak detected in any of the three methods). 1H-MRS diagnostic spectra sensitivity [%] specificity [%] PPV [%] NPV [%] ACC [%] 2HG peak detected 63 100 85,7 89,7 100 93,7 PPV – positive predictive values; NPV – negative predictive values; ACC – accuracy Discussion Our comparative analysis of three distinct 1H-MRS acquisition strategies—short echo (TE 30 ms), intermediate echo (TE 97 ms), and spectral editing (MEGA-PRESS)—presents the diagnostic sensitivity, specificity, and technical feasibility in the detection of the oncometabolite 2-hydroxyglutarate (2HG). We attempted to distinguish the 2HG oncometabolite peak in the spectroscopy spectrum as a marker for the presence of IDH mutations in diffuse gliomas. The intermediate echo time (TE 97 ms) method proved to be a highly specific tool. By optimizing the echo time to minimize signal overlap from glutamate, glutamine, and GABA, this sequence achieved a specificity of 100% in our cohort. While its sensitivity was moderate (51.2%), the high positive predictive value suggests that a detectable peak at 2.25 ppm using this method is highly suitable for confirming an IDH mutation. Its technical simplicity and standard post-processing requirements make it an attractive candidate for routine clinical implementation, particularly as a confirmatory sequence. In contrast, the short echo time (TE 30 ms) method demonstrated the highest sensitivity (88.9%) and overall accuracy (92.5%). However, the interpretation of these spectra is technically demanding due to the complex superposition of metabolite resonances. The detection of 2HG at short TE relies on the deconvolution of the multiplet structures of glutamate and glutamine (Glx). Specifically, the ability to distinguish the 2HG-associated signal (Glx3) at 2.25 ppm from the background Glx4 signal at 2.35 ppm is valuable. Our data indicate that false-negative results in IDH-mutant tumors often result from the merging of these peaks into a single, indistinguishable "Glx slope" descending from the dominant N-acetylaspartate (NAA) peak. The lack of a 2HG peak visible within a tumour with an IDH mutation may be caused by poorly distinguishable peaks at the Glx3 and Glx4 positions when the peak slope merges into a single Glx line on the NAA slope. Also, when intratumoral 2HG concentrations are below the detection threshold of conventional MRS, the method may fail to identify the mutation—it is described by other groups that the concentration of 2HG may be so low that it is impossible to detect using the MRS method [ 14 ]. Nevertheless, the absence of a 2HG peak in diagnostic-quality TE 30 ms spectra serves as a strong marker for IDH-wildtype status, correlating with a more aggressive, high-grade glioma phenotype. Finally, the MEGA-PRESS method, while theoretically superior for isolating the 2HG resonance via J-difference editing, presented significant translational challenges. Although it yielded high specificity (86.7%), it suffered from a substantial non-diagnostic rate (17.5%), primarily due to its susceptibility to magnetic field inhomogeneities and motion artifacts common in clinical settings. A notable observation in our dataset was the presence of a recurrent artefact near 4 ppm in a subset of MEGA-PRESS spectra—a location critically overlapping the edited 2HG signal. This artefact accounted for a substantial proportion of the excluded datasets. Although reminiscent of out-of-voxel echo contamination, we found no published reports describing an analogous phenomenon in MEGA-PRESS 2HG editing. Its etiology remains unclear but may relate to sequence timing interactions, vendor-specific implementation differences, or gradient-related coherence pathways not suppressed by standard crusher schemes. The absence of literature on this artefact highlights an important gap in current understanding and warrants further investigation through phantom studies, sequence simulations, and multi-vendor comparisons. Consequently, while MEGA-PRESS offers refined spectral resolution, our findings support the prioritized use of conventional PRESS sequences—specifically the high-sensitivity TE 30 ms combined with the high-specificity TE 97 ms—as a more reliable protocol for the non-invasive genotyping of diffuse gliomas. Conclusion Proton magnetic resonance spectroscopy targeting the oncometabolite 2-hydroxyglutarate (2HG) represents a highly informative, non-invasive technique that significantly enhances the diagnostic work-up of adult-type diffuse gliomas. Our study demonstrates that while spectral editing via MEGA-PRESS offers theoretical precision, its clinical utility is constrained by a high rate of non-diagnostic acquisitions and susceptibility to artifacts. Consequently, conventional PRESS sequences emerged as the superior approach for routine practice. Specifically, the intermediate echo time (TE 97 ms) method provides optimal diagnostic confidence due to its 100% specificity and ease of technical implementation, making it an ideal confirmatory tool. Complementing this, the short echo time (TE 30 ms) method is performed in all standard MRS examinations and offers high sensitivity, provided that careful spectral analysis is applied to distinguish the 2HG peak from the overlapping Glx/NAA slope. Clinically, the absence of the 2HG signature across these methods is a critical finding, serving as a reliable surrogate marker for IDH-wildtype status and predicting a more aggressive tumor phenotype. Therefore, we recommend a protocol utilizing optimized conventional PRESS spectroscopy as a robust, widely applicable solution for the preoperative determination of glioma genotypes. Declarations Funding: This work is a part of a broader research project supported by the Medical Research Agency, grant number KPOD.07.07-IW.07-0197/24, titled "Radiogenomics as a tool to determine the genotype of the primary brain tumors with multiparametric magnetic resonance imaging with particular usage of spectroscopy (1H-MRS) targeting 2-hydroxyglutarate (2-HG) as an oncometabolite." Conflicts of interest/Competing interests: The authors declare that they have no competing interests. Ethics approval: Ethical approval was obtained from the institutional Ethics Committee (Approval Number: 97/2025; Date: 18.09.2025). The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments. Consent to participate: Informed consent was obtained from all individual participants included in the study. Data Availability Statement: The datasets analysed during the current study are available from the corresponding author on reasonable request. Authors contribution: A.H. and P.W - Conceptualization, Methodology, Investigation, Data curation; S.H - Formal analysis, Visualization, Writing – original draft; P.M - Data curation, Investigation; E.Ch - Investigation (tissue procurement and histological analysis); M.O-W and E.N. - Resources (patient cohort), Supervision; B.B.B. - Conceptualization, Funding acquisition, Supervision, Methodology, Writing – review. All authors have read and agreed to the published version of the manuscript. References Louis DN, Perry A, Wesseling P, Brat DJ, Cree IA, Figarella-Branger D et al (2021) The 2021 WHO Classification of Tumors of the Central Nervous System: a summary. Neuro Oncol 23:1231–1251. https://doi.org/10.1093/neuonc/noab106 Thien Nhat Tran N (2022) The Distribution and Significance of IDH Mutations in Gliomas. 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Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 12 Apr, 2026 Reviews received at journal 10 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviewers agreed at journal 01 Apr, 2026 Reviewers invited by journal 30 Mar, 2026 Editor assigned by journal 30 Mar, 2026 Submission checks completed at journal 30 Mar, 2026 First submitted to journal 30 Mar, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9266342","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":615000994,"identity":"c4655c34-e04b-48ed-931b-e031747f0184","order_by":0,"name":"Anna Hebda","email":"","orcid":"","institution":"Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch","correspondingAuthor":false,"prefix":"","firstName":"Anna","middleName":"","lastName":"Hebda","suffix":""},{"id":615000995,"identity":"a199dd1c-7cbf-4e80-9b48-0742a0d6cf2e","order_by":1,"name":"Pawel Wawrzyniak","email":"","orcid":"","institution":"Maria 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Oncology, Gliwice Branch","correspondingAuthor":false,"prefix":"","firstName":"Malgorzata","middleName":"","lastName":"Oczko-Wojciechowska","suffix":""},{"id":615001001,"identity":"34aa13a7-e026-4460-8a76-37bf11d283c8","order_by":6,"name":"Elzbieta Nowicka","email":"","orcid":"","institution":"Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch","correspondingAuthor":false,"prefix":"","firstName":"Elzbieta","middleName":"","lastName":"Nowicka","suffix":""},{"id":615001002,"identity":"17220af3-b5f6-4dc5-89ff-5596eaa7aed4","order_by":7,"name":"Ewa Chmielik","email":"","orcid":"","institution":"Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch","correspondingAuthor":false,"prefix":"","firstName":"Ewa","middleName":"","lastName":"Chmielik","suffix":""},{"id":615001004,"identity":"db3c386a-665b-4435-94e7-e2a6bcee39d6","order_by":8,"name":"Barbara Bobek-Billewicz","email":"","orcid":"","institution":"Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice Branch","correspondingAuthor":false,"prefix":"","firstName":"Barbara","middleName":"","lastName":"Bobek-Billewicz","suffix":""}],"badges":[],"createdAt":"2026-03-30 11:43:57","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9266342/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9266342/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":105909938,"identity":"23d5f8f2-a334-4664-a6e5-414a928e4bbd","added_by":"auto","created_at":"2026-04-01 10:46:01","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1675655,"visible":true,"origin":"","legend":"\u003cp\u003eExample TE 97ms spectrum.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-9266342/v1/d486f9a995698477a48c3490.png"},{"id":105909966,"identity":"9680ec03-02a9-49c0-ab1f-731b5ef8ef2c","added_by":"auto","created_at":"2026-04-01 10:46:02","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":844181,"visible":true,"origin":"","legend":"\u003cp\u003eA - TE 30 lesion, B - control\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-9266342/v1/83f4704d9b00d577930d203e.png"},{"id":105910805,"identity":"2c4c2dee-bf15-4f37-a785-920f06bd8dd4","added_by":"auto","created_at":"2026-04-01 10:50:54","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1678322,"visible":true,"origin":"","legend":"\u003cp\u003eExample MEGA-PRESS 2HG-edited spectrum.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-9266342/v1/3645daabdd663ab2b2d34c2f.png"},{"id":107480308,"identity":"03c3f436-b491-414b-b73e-bf3293f6b7fa","added_by":"auto","created_at":"2026-04-22 02:07:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4541733,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9266342/v1/b47a6498-0742-4a7d-af14-6f2ee6f3678e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Diagnostic Accuracy of 1H-MRS in Detecting the Oncometabolite 2-Hydroxyglutarate (2HG) in Adult-Type Diffuse Gliomas","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn the 2021 World Health Organization (WHO) classification of Central Nervous System (CNS) tumours, molecular diagnostics have assumed a significant role in the categorization and management of gliomas [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Among the key molecular markers, the isocitrate dehydrogenase (IDH) mutation status is one of the most important prognostic and diagnostic biomarkers, especially in adult-type diffuse gliomas. IDH mutations result in the accumulation (in the cytoplasm of glioma cells with IDH1 mutation and in the mitochondria of cells with IDH2 mutation) of the oncometabolite 2-hydroxyglutarate (2HG) within tumour tissue, providing a critical molecular signature for diagnosis and further prognosis [\u003cspan additionalcitationids=\"CR4\" citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDespite histopathological analysis remaining the gold standard, the non-invasive detection of IDH mutation status is important for prognostication and therapeutic decision-making. Nowadays, radiogenomics is an evolving field of study that utilises advances in image acquisition and analysis to correlate imaging features with molecular markers of diseases. It focuses on the relationship between genomics and imaging phenotypes, and has been widely applied to address tumour heterogeneity and predict immune responsiveness and progression [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Preoperative non-invasive methods for verifying mutation status could greatly influence patient management, especially when considering the risks associated with biopsy in eloquent brain areas or in differentiating gliomas. The development of a protocol including 1H-MRS spectroscopy focused on the detection of 2HG will enable the non-invasive determination of IDH [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan additionalcitationids=\"CR8 CR9 CR10\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThis study investigates the effectiveness of 1H-MRS in detecting 2-hydroxyglutarate (2HG) in brain tumours, specifically in adult-type diffuse gliomas. We implemented three 1H-MRS strategies to check how effective these spectroscopy methods are in detecting 2HG. We used a short echo time (TE 30 ms) sequence, an intermediate echo time (TE 97 ms) PRESS sequence, and the MEGA-PRESS method to improve non-invasive diagnostic methods.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cp\u003eA total of 152 adult-type diffuse glioma patients treated between January 2020 and October 2025 were included in the analysis. All patients underwent preoperative multiparametric magnetic resonance imaging prior to planned surgery or biopsy, and had available histopathological and genetic test results. The protocol included standard morphological sequences and optimized spectroscopy 1H-MRS providing detection of the oncometabolite 2HG. Clinical data, tumour characteristics, and genetic markers such as IDH1 mutation, MGMT promoter methylation, TERT pathogenic variant, and the appearance of microvascular proliferation and/or foci of necrosis were collected. In this study, we focused on the evaluation of IDH1 mutation status. IDH2 mutations were not considered in our analysis, as IDH2 status was not evaluated in a subset of the included cases.\u003c/p\u003e\n\u003cp\u003eThree spectroscopic methods were employed to assess lesion IDH mutation status by 2HG detection. For solid-appearing lesions, spectra were obtained from the centre. In contrast-enhancing lesions, spectra were acquired from the enhancing part unless an explicit necrotic core was present in the lesion centre, which was avoided in voxel volume. During each examination, basic long (135 ms) and short (30 ms) echo time spectra were acquired from the lesion and normal-appearing brain tissue, in addition to MEGA-PRESS and TE 97 ms acquisitions from the lesion.\u003c/p\u003e\n\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eIntermediate (97 ms) Echo Time Spectra\u003c/h2\u003e\n \u003cp\u003eThe first method was the intermediate echo time (TE) PRESS (Point RESolved Spectroscopy) sequence with TE 97 ms. This specific TE was chosen to minimize the contribution of other overlapping metabolites (GABA, glutamate, and glutamine) for 2HG detection [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The sequence consisted of 160 averages with a repetition time (TR) of 2000 ms. Voxels were cuboids 20x20x20 mm or bigger, so the minimal volume was 8 cm\u0026sup3;. In the case of smaller lesions where the prescribed voxel was bigger than the lesion, partial volume effects were accepted. An automatic shimming procedure was performed unless it produced poor homogeneity, in which case manual adjustments were performed.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eShort (30 ms) Echo Time Spectra\u003c/h3\u003e\n\u003cp\u003eThis method is based on standard TE 30 ms voxels acquired during routine MRS examinations [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Information about 2HG is derived during post-processing. Two Gauss peaks are fitted into data from the lesion and normal-appearing brain tissue. These peaks are Glx3 with 2HG at 2.25\u0026ndash;2.35 ppm and Glx4 at 2.31\u0026ndash;2.40 ppm. The reasoning behind this method is that 2HG contributes to the overall integral of Glx3 in the lesion compared to that in the reference voxel, and it does not contribute to the Glx4 peak. Comparing integrals of these fitted peaks follows simple math:\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003ePositive values indicate the presence of the 2HG peak and negative values deny it. Acquisition employs a standard PRESS sequence with 80 averages and a TR of 2000 ms. Voxel sizes vary significantly to avoid partial volume effects. Similarly to TE 97 ms acquisition, an automatic shim procedure was used with manual adjustments if needed.\u003c/p\u003e\n\u003ch3\u003eMEGA-PRESS Acquisition\u003c/h3\u003e\n\u003cp\u003eThe third method was MEGA-PRESS (Mescher Garwood Point Resolved Spectroscopy), which uses spectra editing pulses to null metabolites overlapping with 2HG [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. MEGA-PRESS consists of two separate acquisitions: one with editing pulses and another without it. The difference spectra is then calculated, leaving only metabolites that got disturbed by the editing pulse. The sequence is originally aimed at quantifying GABA, but since 2HG has similar protons resonating at 1.9 ppm (sensitive to editing pulses), it is present in the difference spectra.\u003c/p\u003e\n\u003cp\u003eThree spectra were obtained from every lesion: water-suppressed MEGA-PRESS, one without water suppression for eddy current correction, and a TE 30 ms PRESS spectra for internal water peak reference. Water-suppressed acquisition consisted of 96 averages (two sets of 48 averages) with a TE of 68 ms. Unsuppressed acquisition had 16 (two sets of 8) averages, and water reference TE 30 ms had 16 averages. In all cases, a TR of 2000 ms was used. Voxel sizes for MEGA-PRESS followed a similar pattern to TE 97 ms. Automatic shim followed by manual adjustment, if needed, was performed.\u003c/p\u003e\n\u003cp\u003eTE 97 ms and MEGA-PRESS were analyzed by LCModel software with simulated basis sets. All simulations were performed by FID-A in the MATLAB environment. The MEGA-PRESS basis set contained these metabolites: NAA, NAAG, Lac, GSH, Glu, Gln, GABA, and 2HG. The TE 97 ms basis set contained: Ala, Asp, Cr, PCr, GABA, Glc, Gln, Glu, GPC, GSH, 2HG, Ins, Lac, NAA, NAAG. Spectra were fitted and the Cramer-Rao Lower Bound (CRLB) was assessed to determine whether the 2HG peak was present or not.\u003c/p\u003e\n\u003cp\u003eGauss fits for Glx3 and Glx4 peaks were added to the automated post-processing pipeline of the MR Spectroscopy application on syngo.via software (Siemens, Erlangen Germany). Peak integrals were used in calculations. Two phantoms containing brain metabolites in nominal concentrations were used for testing. One phantom had 2HG. These acquisitions were tested on such phantoms using the above parameters.\u003c/p\u003e\n\u003cp\u003eStatistical analysis was performed on data achieved for the detection of the 2HG oncometabolite in both tumour samples and reference spectra obtained during examinations performed on patients and dedicated phantoms. The correlation of 2HG occurrence with molecular diagnosis and the determination of accuracy, sensitivity, and specificity for the validated method were verified.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eA total of 152 patients with adult-type diffuse gliomas underwent proton MR spectroscopy as part of a 3T MRI examination protocol extended with single-voxel PRESS and MEGA-PRESS acquisitions for the non-invasive detection of 2-hydroxyglutarate (2HG). The study cohort comprised 69 women and 83 men, with a mean age of 46\u0026thinsp;\u0026plusmn;\u0026thinsp;13 years. IDH mutation status was available for all patients: 84/152 (55%) were IDH-mutant [IDH(+)] and 68/152 (45%) were IDH-wild-type [IDH(-)].\u003c/p\u003e \u003cp\u003eThe analysed group comprised 54 out of 152 (36%) WHO G2 tumours, 26 out of 152 (17%) were G3 tumours, and the remaining 72 out of 152 (47%) were wild-type G4 tumours. The analysed group comprised 66 cases of IDH1-mutant astrocytoma (43 G2, 19 G3, 4 G4), 18 cases of IDH1-mutant oligodendroglioma with 1p/19q codeletion (11 for G2, 7 for G3), and the remaining 68 cases were G4 wild-type, of which 32 were histopathological glioblastomas with necrosis and proliferation of small vessels, whilst the remaining 34 were wild-type astrocytomas.\u003c/p\u003e \u003cp\u003eMost patients exhibited high-grade features in histopathological evaluation with MVP and necrosis for G4 tumors, including prominent microvascular proliferation (MVP). Furthermore, nearly half of the G4 cases had TERT promoter mutations, the assessment of which has recently become a standard component of molecular diagnostics. In some patients, necrosis within tumors classified as molecular glioblastomas (molecular GBM) caused underscoring of the histopathological and molecular heterogeneity of these lesions.\u003c/p\u003e \u003cp\u003eThe number of MR spectroscopies performed using individual methods, specifying the number of non-diagnostic spectra, is presented in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. Achieving consistently high-quality MEGA-PRESS spectra proved challenging, which ultimately compromised the sensitivity of the method.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThe amount of 1H-MRS performed using individual methods.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e1H-MRS\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cem\u003eAll spectra\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e\u003cem\u003eNon-diagnostic spectra\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eDiagnostic spectra\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e97ms\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e152\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMEGA-PRESS\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e14 (17,5%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e66\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e30ms\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3 (2%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e147\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eData analysis was performed using two complementary approaches. First, each spectroscopy method (PRESS TE 97 ms, PRESS TE 30 ms, MEGA-PRESS) was evaluated independently, reflecting differences in group sizes related to the later introduction of MEGA-PRESS into the clinical protocol. Second, diagnostic performance was analyzed in the subgroup of patients who underwent all three spectroscopy techniques.\u003c/p\u003e\n\u003ch3\u003eIntermediate-Echo PRESS (TE = 97 ms)\u003c/h3\u003e\n\u003cp\u003eA total of 152 patients had diagnostic-quality spectra acquired with TE 97 ms. The 2HG peak was identified in 43/84 IDH(+) cases (51.2%), whereas all IDH(-) cases showed no detectable 2HG. In the Intermediate-Echo PRESS method, none of the wild-type tumours exhibited a 2HG peak.\u003c/p\u003e \u003cp\u003eThe upper limit of significance was set at 50% SD of the fit based on the CRLB (Cram\u0026eacute;r-Rao Lower Bound) of 2HG in the spectrum analysed using LCModel. Above this value, it was assumed that the estimation uncertainty was too high and, therefore, that there was no contribution of 2HG to the spectrum. Based on these results, the diagnostic sensitivity of TE 97 ms PRESS was 51.2%, with a specificity of 100% and an overall accuracy of 73.0%. The positive and negative predictive values (PPV and NPV) were 100% and 62.4%, respectively.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eShort-Echo PRESS (TE\u0026thinsp;=\u0026thinsp;30 ms)\u003c/h2\u003e \u003cp\u003eShort-echo PRESS spectra were acquired in 150 patients; 3 spectra were of low quality, so analysis was performed for 147 patients. For this method, the most important factor is the quality of the spectrum obtained, meaning whether we are able to distinguish the peak in the Glx slope at approximately 2.25 ppm and approximately 2.35 ppm, assigning them to Glx3 and Glx4, respectively. In two patients, analysis was not possible\u0026mdash;one patient had an additional high peak at 2.38 ppm, distorting the spectrum for Glx4; in another patient, the Glx slope was almost a straight line with no distinct peaks.\u003c/p\u003e \u003cp\u003eA detectable 2HG oncometabolite peak was observed in 74 patients. The calculated ratio of Glx3 to Glx4 yielded the following median values: for IDH(-) and no 2HG visualized it was 0.48; for IDH(+) with the presence of 2HG confirmed in the spectrum, the median value was 1.38. For all reference spectra, the median Glx3/Glx4 was 0.91. We set the threshold for the occurrence of the 2HG peak as positive values (\u0026gt;\u0026thinsp;0%) in the equation.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e72/81 IDH(+) patients (88.9%), while 64/66 IDH(-) patients (97.0%) demonstrated no measurable 2HG. The resulting diagnostic sensitivity was 88.9%, with a specificity of 97.0% and an overall accuracy of 92.5%. The PPV and NPV were 97.3% and 87.7%, respectively.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eMEGA-PRESS Acquisition Analysis\u003c/h3\u003e\n\u003cp\u003eMEGA-PRESS 2HG-edited spectroscopy was performed in 80 patients; however, 14/80 spectra (17.5%) were non-diagnostic, leaving 66 spectra suitable for interpretation. The number of spectra analysed for this method is lower than for the other methods due to the shorter period of time during which exams using this sequence were performed. As in the TE 97 ms method, we set a value of 50% SD of the fit as the significance threshold for the occurrence of 2HG in the spectrum.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAmong evaluable cases, the 2HG signal was detected in 26/36 IDH(+) patients (72.2%), while no 2HG was found in 26/30 IDH(-) patients (86.7%). The calculated sensitivity, specificity, and accuracy for MEGA-PRESS were 72.2%, 86.7%, and 78.8%, respectively. The PPV was 86.7% and the NPV was 72.2%.\u003c/p\u003e \u003cp\u003eAlthough MEGA-PRESS demonstrated unique spectral editing capabilities, it also showed the highest proportion of non-diagnostic examinations (17.5%). This elevated failure rate highlights the susceptibility of the edited sequence to artefacts and technical limitations not observed to the same extent in conventional PRESS acquisitions. A comparison of the three used 1H-MRS methods is presented in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of the spectroscopy methods used in the study.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"8\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c8\" colnum=\"8\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e1H-MRS\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eall spectra\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003ediagnostic spectra\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003esensitivity [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003especificity [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003ePPV [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eNPV [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c8\"\u003e \u003cp\u003eACC [%]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e97 ms\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e152\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e51,2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e62,4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e73,0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e30 ms\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e150\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e147\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e88,9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e97,0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e97,3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e87,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e92,5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003eMEGA-PRESS\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e80\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e66\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e72,2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e86,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e86,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c7\"\u003e \u003cp\u003e72,2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c8\"\u003e \u003cp\u003e78,8\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003ch3\u003ePPV – positive predictive values; NPV – negative predictive values; ACC – accuracy\u003c/h3\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eCombined Analysis of Three 1H-MRS Methods\u003c/h2\u003e \u003cp\u003eIn the combined analysis of all three MR spectroscopy\u0026ndash;based methods (in 63 patients three diagnostic spectroscopic methods were obtained in a single examination), the presence of the oncometabolite 2HG was detected in a substantial proportion of IDH-mutant gliomas. Specifically, a 2HG peak was identifiable in at least one method in all 35/63 IDH-positive cases, whereas unexpected 2HG positivity was observed in 4 (2 GBM and 2 astrocytomas) out of 28/63 wildtype lesions.\u003c/p\u003e \u003cp\u003eOverall diagnostic performance for detecting a 2HG peak using any of the three approaches is summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. When considering all positive detections, the combined methods achieved a sensitivity of 100%, specificity of 85.7%, positive predictive value of 89.7%, negative predictive value of 100%, and an overall accuracy of 93.7%.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCombined analysis of all three MR spectroscopy\u0026ndash;based methods (2HG peak detected in any of the three methods).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cem\u003e1H-MRS\u003c/em\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003ediagnostic spectra\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003esensitivity [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003especificity [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003ePPV [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eNPV [%]\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eACC [%]\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e\u003cb\u003e2HG peak detected\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e85,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e89,7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e93,7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003ePPV \u0026ndash; positive predictive values; NPV \u0026ndash; negative predictive values; ACC \u0026ndash; accuracy\u003c/h2\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur comparative analysis of three distinct 1H-MRS acquisition strategies\u0026mdash;short echo (TE 30 ms), intermediate echo (TE 97 ms), and spectral editing (MEGA-PRESS)\u0026mdash;presents the diagnostic sensitivity, specificity, and technical feasibility in the detection of the oncometabolite 2-hydroxyglutarate (2HG). We attempted to distinguish the 2HG oncometabolite peak in the spectroscopy spectrum as a marker for the presence of IDH mutations in diffuse gliomas.\u003c/p\u003e \u003cp\u003eThe intermediate echo time (TE 97 ms) method proved to be a highly specific tool. By optimizing the echo time to minimize signal overlap from glutamate, glutamine, and GABA, this sequence achieved a specificity of 100% in our cohort. While its sensitivity was moderate (51.2%), the high positive predictive value suggests that a detectable peak at 2.25 ppm using this method is highly suitable for confirming an IDH mutation. Its technical simplicity and standard post-processing requirements make it an attractive candidate for routine clinical implementation, particularly as a confirmatory sequence.\u003c/p\u003e \u003cp\u003eIn contrast, the short echo time (TE 30 ms) method demonstrated the highest sensitivity (88.9%) and overall accuracy (92.5%). However, the interpretation of these spectra is technically demanding due to the complex superposition of metabolite resonances. The detection of 2HG at short TE relies on the deconvolution of the multiplet structures of glutamate and glutamine (Glx). Specifically, the ability to distinguish the 2HG-associated signal (Glx3) at 2.25 ppm from the background Glx4 signal at 2.35 ppm is valuable. Our data indicate that false-negative results in IDH-mutant tumors often result from the merging of these peaks into a single, indistinguishable \"Glx slope\" descending from the dominant N-acetylaspartate (NAA) peak. The lack of a 2HG peak visible within a tumour with an IDH mutation may be caused by poorly distinguishable peaks at the Glx3 and Glx4 positions when the peak slope merges into a single Glx line on the NAA slope. Also, when intratumoral 2HG concentrations are below the detection threshold of conventional MRS, the method may fail to identify the mutation\u0026mdash;it is described by other groups that the concentration of 2HG may be so low that it is impossible to detect using the MRS method [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Nevertheless, the absence of a 2HG peak in diagnostic-quality TE 30 ms spectra serves as a strong marker for IDH-wildtype status, correlating with a more aggressive, high-grade glioma phenotype.\u003c/p\u003e \u003cp\u003eFinally, the MEGA-PRESS method, while theoretically superior for isolating the 2HG resonance via J-difference editing, presented significant translational challenges. Although it yielded high specificity (86.7%), it suffered from a substantial non-diagnostic rate (17.5%), primarily due to its susceptibility to magnetic field inhomogeneities and motion artifacts common in clinical settings.\u003c/p\u003e \u003cp\u003eA notable observation in our dataset was the presence of a recurrent artefact near 4 ppm in a subset of MEGA-PRESS spectra\u0026mdash;a location critically overlapping the edited 2HG signal. This artefact accounted for a substantial proportion of the excluded datasets. Although reminiscent of out-of-voxel echo contamination, we found no published reports describing an analogous phenomenon in MEGA-PRESS 2HG editing. Its etiology remains unclear but may relate to sequence timing interactions, vendor-specific implementation differences, or gradient-related coherence pathways not suppressed by standard crusher schemes. The absence of literature on this artefact highlights an important gap in current understanding and warrants further investigation through phantom studies, sequence simulations, and multi-vendor comparisons.\u003c/p\u003e \u003cp\u003eConsequently, while MEGA-PRESS offers refined spectral resolution, our findings support the prioritized use of conventional PRESS sequences\u0026mdash;specifically the high-sensitivity TE 30 ms combined with the high-specificity TE 97 ms\u0026mdash;as a more reliable protocol for the non-invasive genotyping of diffuse gliomas.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eProton magnetic resonance spectroscopy targeting the oncometabolite 2-hydroxyglutarate (2HG) represents a highly informative, non-invasive technique that significantly enhances the diagnostic work-up of adult-type diffuse gliomas. Our study demonstrates that while spectral editing via MEGA-PRESS offers theoretical precision, its clinical utility is constrained by a high rate of non-diagnostic acquisitions and susceptibility to artifacts. Consequently, conventional PRESS sequences emerged as the superior approach for routine practice.\u003c/p\u003e \u003cp\u003eSpecifically, the intermediate echo time (TE 97 ms) method provides optimal diagnostic confidence due to its 100% specificity and ease of technical implementation, making it an ideal confirmatory tool. Complementing this, the short echo time (TE 30 ms) method is performed in all standard MRS examinations and offers high sensitivity, provided that careful spectral analysis is applied to distinguish the 2HG peak from the overlapping Glx/NAA slope. Clinically, the absence of the 2HG signature across these methods is a critical finding, serving as a reliable surrogate marker for IDH-wildtype status and predicting a more aggressive tumor phenotype. Therefore, we recommend a protocol utilizing optimized conventional PRESS spectroscopy as a robust, widely applicable solution for the preoperative determination of glioma genotypes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eFunding:\u003c/strong\u003e This work is a part of a broader research project supported by the Medical Research Agency, grant number KPOD.07.07-IW.07-0197/24, titled \u0026quot;Radiogenomics as a tool to determine the genotype of the primary brain tumors with multiparametric magnetic resonance imaging with particular usage of spectroscopy (1H-MRS) targeting 2-hydroxyglutarate (2-HG) as an oncometabolite.\u0026quot;\u003c/li\u003e\n \u003cli\u003e\u003cstrong\u003eConflicts of interest/Competing interests:\u003c/strong\u003e\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eEthics approval:\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003e\u0026nbsp;Ethical approval was obtained from the institutional Ethics Committee (Approval Number: 97/2025; Date: 18.09.2025). The study was performed in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments.\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eConsent to participate:\u003c/strong\u003e\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eInformed consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eData Availability Statement:\u003c/strong\u003e\u0026nbsp;\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eThe datasets analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n\u003cul type=\"disc\"\u003e\n \u003cli\u003e\u003cstrong\u003eAuthors contribution:\u003c/strong\u003e\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eA.H. and P.W \u0026nbsp;- Conceptualization, Methodology, Investigation, Data curation; \u0026nbsp; S.H - Formal analysis, Visualization, Writing \u0026ndash; original draft; P.M \u0026nbsp;- Data curation, Investigation; \u0026nbsp;E.Ch - Investigation (tissue procurement and histological analysis); \u0026nbsp;M.O-W and E.N. - Resources (patient cohort), Supervision; B.B.B. - Conceptualization, Funding acquisition, Supervision, Methodology, Writing \u0026ndash; review.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll authors have read and agreed to the published version of the manuscript.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eLouis DN, Perry A, Wesseling P, Brat DJ, Cree IA, Figarella-Branger D et al (2021) The 2021 WHO Classification of Tumors of the Central Nervous System: a summary. 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J Clin Oncol 2016;34. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1200/JCO.2016.67.1222\u003c/span\u003e\u003cspan address=\"10.1200/JCO.2016.67.1222\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePark SI, Suh CH, Guenette JP, Huang RY, Kim HS (2021) The T2-FLAIR mismatch sign as a predictor of IDH-mutant, 1p/19q-noncodeleted lower-grade gliomas: a systematic review and diagnostic meta-analysis. 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Neuro Oncol 20:1573\u0026ndash;1583. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/neuonc/noy113\u003c/span\u003e\u003cspan address=\"10.1093/neuonc/noy113\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAutry AW, Lafontaine M, Jalbert L, Phillips E, Phillips JJ, Villanueva-Meyer J et al (2022) Spectroscopic imaging of D-2-hydroxyglutarate and other metabolites in pre-surgical patients with IDH-mutant lower-grade gliomas. J Neurooncol 159:43\u0026ndash;52. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s11060-022-04042-3\u003c/span\u003e\u003cspan address=\"10.1007/s11060-022-04042-3\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBranzoli F, Di Stefano AL, Capelle L, Ottolenghi C, Valabr\u0026egrave;gue R, Deelchand DK et al (2018) Highly specific determination of IDH status using edited in vivo magnetic resonance spectroscopy. Neuro Oncol 20. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1093/neuonc/nox214\u003c/span\u003e\u003cspan address=\"10.1093/neuonc/nox214\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eProvencher SW (1993) Estimation of metabolite concentrations from localized in vivo proton NMR spectra. Magn Reson Med 30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/mrm.1910300604\u003c/span\u003e\u003cspan address=\"10.1002/mrm.1910300604\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMuoio B, Van Dijken BRJ, Jeltema H-R, Kłos J, Van Jan P, Enting RH et al The Correlation of In Vivo MR Spectroscopy and Ex Vivo 2-Hydroxyglutarate Concentration for the Prediction of Isocitrate Dehydrogenase Mutation Status in Diffuse Glioma 2023. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/diagnostics13172791\u003c/span\u003e\u003cspan address=\"10.3390/diagnostics13172791\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSimpson R, Devenyi GA, Jezzard P, Hennessy TJ, Near J (2017) Advanced processing and simulation of MRS data using the FID appliance (FID-A)\u0026mdash;An open source, MATLAB-based toolkit. Magn Reson Med 77. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/mrm.26091\u003c/span\u003e\u003cspan address=\"10.1002/mrm.26091\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMuoio B, Van Dijken BRJ, Jeltema H-R, Kłos J, Van Jan P, Enting RH et al The Correlation of In Vivo MR Spectroscopy and Ex Vivo 2-Hydroxyglutarate Concentration for the Prediction of Isocitrate Dehydrogenase Mutation Status in Diffuse Glioma 2023. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.3390/diagnostics13172791\u003c/span\u003e\u003cspan address=\"10.3390/diagnostics13172791\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-neuro-oncology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"neon","sideBox":"Learn more about [Journal of Neuro-Oncology](https://www.springer.com/journal/11060)","snPcode":"11060","submissionUrl":"https://submission.nature.com/new-submission/11060/3","title":"Journal of Neuro-Oncology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"1H-MRS, 2-hydroxyglutarate, IDH mutation, diffuse glioma, radiogenomics, neuro-oncology","lastPublishedDoi":"10.21203/rs.3.rs-9266342/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9266342/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo evaluate the diagnostic accuracy of three proton magnetic resonance spectroscopy (1H-MRS) strategies\u0026mdash;short echo (TE 30 ms), intermediate echo (TE 97 ms), and MEGA-PRESS\u0026mdash;for detecting the oncometabolite 2-hydroxyglutarate (2HG) to non-invasively determine isocitrate dehydrogenase (IDH) mutation status in adult-type diffuse gliomas.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA cohort of 152 patients with adult-type diffuse gliomas (84 IDH-mutant, 68 IDH-wild-type) underwent preoperative 3T MRI incorporating standard morphological sequences and 1H-MRS acquisitions. Spectra were evaluated to assess the presence of a 2HG peak. Diagnostic performance was analysed independently for each method and collectively for a subgroup of patients receiving all three sequences.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe intermediate echo (TE 97 ms) method demonstrated 100% specificity and 51.2% sensitivity, while the short echo (TE 30 ms) sequence achieved 97% specificity and 88.9% sensitivity. The MEGA-PRESS method yielded 86.7% specificity and 72.2% sensitivity but was limited by a high non-diagnostic rate (17.5%) due to artifact susceptibility. When combined, the spectroscopy methods achieved 100% sensitivity, 85.7% specificity, and 93.7% overall accuracy in detecting 2HG.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eConventional PRESS sequences (TE 30 ms and TE 97 ms) outperform MEGA-PRESS for the routine clinical detection of 2HG due to higher technical reliability. An optimized conventional PRESS protocol offers a robust, highly accurate, and non-invasive preoperative tool for identifying glioma genotypes and predicting tumor phenotypes.\u003c/p\u003e","manuscriptTitle":"Diagnostic Accuracy of 1H-MRS in Detecting the Oncometabolite 2-Hydroxyglutarate (2HG) in Adult-Type Diffuse Gliomas","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-01 10:17:26","doi":"10.21203/rs.3.rs-9266342/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-12T21:28:57+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-04-10T21:00:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"74193587212777253887180843793848599126","date":"2026-04-01T20:14:09+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"160638911103266804691743572047056387162","date":"2026-04-01T12:42:26+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-03-30T20:00:24+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-03-30T19:27:15+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-03-30T19:26:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Neuro-Oncology","date":"2026-03-30T11:27:31+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-neuro-oncology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"neon","sideBox":"Learn more about [Journal of Neuro-Oncology](https://www.springer.com/journal/11060)","snPcode":"11060","submissionUrl":"https://submission.nature.com/new-submission/11060/3","title":"Journal of Neuro-Oncology","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"bcf92741-a165-48f6-8f6e-74280082d0bb","owner":[],"postedDate":"April 1st, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-04-28T10:40:31+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-01 10:17:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9266342","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9266342","identity":"rs-9266342","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}