MRI evaluation of pediatric ovarian tumors: morphological features and preliminary assessment of diffusion-weighted imaging

Background Ovarian tumors in children and adolescents represent a diagnostically challenging and heterogeneous group of diseases. Accurate preoperative differentiation between benign and malignant lesions is essential for optimal treatment planning and preservation of reproductive potential. Magnetic resonance imaging (MRI) plays a key role in the evaluation of indeterminate adnexal masses; however, conventional morphological MRI features often overlap between benign and malignant tumors. Diffusion-weighted imaging (DWI) may provide additional diagnostic information by reflecting tumor cellularity.

This multicenter retrospective observational study included pediatric patients with suspected ovarian tumors examined at two tertiary referral centers between 2020 and 2025. A total of 152 patients with suspected ovarian tumors were initially evaluated by ultrasound, of whom 96 underwent pelvic MRI due to diagnostic uncertainty. Histopathological confirmation was available for all 96 patients who underwent MRI and served as the reference standard. Diffusion-weighted imaging with apparent diffusion coefficient (ADC) mapping was performed in a subset of 32 patients. MRI assessment included analysis of tumor morphology, presence of solid components, contour characteristics, extracapsular extension, ascites, lymphadenopathy, and peritoneal deposits. Diagnostic performance of MRI and DWI was assessed using receiver operating characteristic (ROC) analysis.

Several morphological MRI features, including solid components, irregular margins, extracapsular growth, ascites, lymphadenopathy, and peritoneal deposits, were significantly more frequent in malignant tumors (p < 0.001). Tumor size and cystic–solid architecture alone were not reliable indicators of malignancy. ADC values of the solid tumor component were significantly lower in malignant compared with benign lesions (0.8 ± 0.09 × 10⁻³ mm²/s vs. 1.2 ± 0.13 × 10⁻³ mm²/s, p = 0.019). ROC analysis demonstrated high diagnostic accuracy of MRI based on morphological features (AUC = 0.94). The combined use of morphological MRI and DWI improved diagnostic performance, with a sensitivity of 91.0%, specificity of 88.0%, and overall accuracy of 89.0%.

MRI is a highly informative modality for the evaluation of ovarian tumors in children and adolescents; however, conventional morphological criteria alone may be insufficient, particularly in early-stage malignant epithelial tumors. Diffusion-weighted imaging with quantitative ADC assessment may provide additional diagnostic information for differentiating benign and malignant ovarian tumors. A comprehensive MRI approach incorporating both morphological and functional parameters may enhance diagnostic confidence and support optimal clinical decision-making in pediatric patients. Similar content being viewed by others

Ovarian tumors in children and adolescents represent a rare but clinically significant group of diseases characterized by marked histological heterogeneity and variable biological behavior [1, 2]. Although ovarian neoplasms account for a small proportion of pediatric tumors, their timely and accurate diagnosis is essential, as delayed or incorrect assessment may lead to suboptimal treatment strategies, unnecessary radical surgery, and potential loss of reproductive function [3]. In pediatric patients, preservation of ovarian tissue and fertility remains a critical consideration alongside oncological safety [4]. Ultrasound is widely used as the first-line imaging modality for the evaluation of adnexal masses in children due to its availability, absence of ionizing radiation, and high sensitivity in detecting ovarian lesions [5]. However, ultrasound findings are often nonspecific, particularly in cases of large, complex, or atypically located tumors. As a result, diagnostic uncertainty frequently persists, necessitating further imaging evaluation [6]. Magnetic resonance imaging (MRI) plays a pivotal role in the assessment of indeterminate ovarian masses in pediatric patients. Owing to its excellent soft-tissue contrast, multiplanar imaging capability, and lack of ionizing radiation, MRI is considered the most informative cross-sectional imaging technique for pelvic evaluation in children and adolescents [7, 8]. Conventional MRI allows detailed assessment of tumor morphology, internal architecture, signal characteristics, and extent of disease, which are essential for preoperative planning [9]. Despite these advantages, differentiation between benign and malignant ovarian tumors based solely on conventional morphological MRI features remains challenging in pediatric practice [10]. Several imaging characteristics traditionally associated with malignancy—such as the presence of solid components, heterogeneous signal intensity, irregular margins, and complex cystic–solid architecture—may also be observed in benign lesions, including mature teratomas and certain epithelial tumors [11, 12]. This overlap of imaging features significantly limits the specificity of standard morphological MRI assessment and may result in diagnostic ambiguity [13]. Advanced MRI techniques, particularly diffusion-weighted imaging (DWI), have emerged as promising tools for improving diagnostic accuracy in oncologic imaging [14]. DWI provides functional information related to tissue cellularity and microstructural organization by evaluating the diffusion of water molecules within tissues. Quantitative analysis using apparent diffusion coefficient (ADC) values allows objective assessment of diffusion restriction, which is typically more pronounced in highly cellular malignant tumors [15, 16]. In adult populations, the diagnostic value of DWI in characterizing ovarian tumors has been widely reported; however, data in pediatric and adolescent patients remain limited and inconsistent [17]. Furthermore, the application of DWI in children presents additional challenges related to age-dependent pelvic anatomy, motion artifacts, and the heterogeneous histological spectrum of pediatric ovarian tumors [18]. In particular, malignant epithelial ovarian tumors in children may demonstrate subtle or nonspecific morphological features on conventional MRI, increasing the risk of underestimation of malignant potential at early stages [19]. Given these diagnostic challenges, there is a clear need for comprehensive evaluation of both morphological and functional MRI parameters in pediatric ovarian tumors. Assessing the added value of DWI and quantitative ADC measurements may help refine preoperative diagnosis, reduce false-negative interpretations, and support more accurate risk stratification [20]. Therefore, the aim of this multicenter retrospective study was to evaluate the diagnostic performance of MRI in differentiating benign and malignant ovarian tumors in children and adolescents, with particular emphasis on the additional value of diffusion-weighted imaging and quantitative ADC analysis. However, evidence regarding the diagnostic value of diffusion-weighted imaging in pediatric ovarian tumors remains limited, highlighting the need for further research in this field.

Study design and setting This multicenter retrospective observational study was conducted at two tertiary pediatric referral centers: the clinics of the Tashkent Pediatric Medical Institute and the Scientific and Practical Medical Center of Pediatric Oncology, Hematology and Immunology. The study period covered January 2020 to December 2025. The study protocol was approved by the local institutional ethics committees of both participating centers. Due to the retrospective nature of the study, the requirement for informed consent was waived. This study was a retrospective observational study and was not a clinical trial. Patients During the study period, a total of 152 children and adolescents with suspected ovarian tumors were initially evaluated by ultrasound. Pelvic magnetic resonance imaging (MRI) was subsequently performed in 96 patients due to diagnostic uncertainty following ultrasound examination. Histopathological confirmation of diagnosis was available for all 96 patients who underwent MRI and served as the reference standard for the study. Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping was available in a subset of 32 patients. Based on histopathological findings, tumors were classified as benign or malignant, and various histological subtypes were included in the analysis. Inclusion criteria were: pediatric and adolescent patients with suspected ovarian tumors, availability of pelvic MRI examination, histopathological confirmation of diagnosis. Exclusion criteria were: absence of MRI data, incomplete imaging datasets, lack of histological verification. MRI acquisition protocol Pelvic MRI examinations were performed using two scanners: a 1.5-T system (Magnetom Sonata, Siemens Healthcare, Erlangen, Germany) and a 3.0-T system (Achieva, Philips Healthcare, Best, the Netherlands). Imaging was performed according to a standardized institutional protocol at both participating centers. The MRI protocol included axial, sagittal, and coronal sequences. Conventional MRI sequences comprised T1-weighted imaging, T2-weighted imaging, and fat-suppressed sequences when indicated. Typical imaging parameters were as follows: T1-weighted imaging with repetition time (TR) approximately 500–700 ms and echo time (TE) 10–15 ms; T2-weighted imaging with TR approximately 3500–4500 ms and TE 90–120 ms; slice thickness 4–5 mm. Diffusion-weighted imaging was performed using b-values of 0 and 1000 s/mm², and apparent diffusion coefficient (ADC) maps were automatically generated. Diffusion-weighted imaging was not routinely included in the MRI protocol during the early phase of the study period and was introduced later; therefore, DWI sequences were available only in a subset of patients. Intravenous gadolinium-based contrast agents were administered when clinically indicated and when not contraindicated at a standard dose of 0.1 mmol/kg. Image analysis All MRI examinations were independently reviewed by two experienced radiologists specializing in pediatric imaging. Both radiologists were blinded to the histopathological results during image evaluation. In cases of disagreement, consensus was reached through joint review. The following morphological MRI features were evaluated: tumor size and location, internal architecture (cystic, solid, or cystic–solid), presence of solid components, tumor margins (smooth or irregular), extracapsular extension, presence of ascites, regional lymphadenopathy, peritoneal deposits, laterality (unilateral or bilateral involvement). Diffusion-weighted imaging and ADC analysis DWI analysis was performed separately for cystic and solid tumor components. Circular regions of interest (ROIs) ranging from approximately 20–50 mm² were manually placed within the most representative solid areas of the tumor while carefully avoiding necrotic, hemorrhagic, and cystic components. In heterogeneous tumors, ROIs were positioned within the visually most solid portion of the lesion on the ADC map with reference to the corresponding T2-weighted images. ADC measurements were performed three times in each lesion, and the mean value was used for statistical analysis. ADC values were expressed in ×10⁻³ mm²/s. Statistical analysis Statistical analysis was performed using SPSS statistical software (version 26, IBM Corp., Armonk, NY, USA). Continuous variables were expressed as mean ± standard deviation or median with range, while categorical variables were presented as absolute numbers and percentages. Comparisons between benign and malignant tumors were performed using the chi-square test or Fisher’s exact test for categorical variables and Student’s t-test for continuous variables. A p-value < 0.05 was considered statistically significant. Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic performance of MRI features and diffusion-weighted imaging. Sensitivity, specificity, and overall diagnostic accuracy were calculated using histopathological findings as the reference standard.

Patient characteristics During the study period, 152 children and adolescents with suspected ovarian tumors were evaluated at the two participating centers. Pelvic MRI was performed in 96 patients due to inconclusive ultrasound findings. Histopathological confirmation was available for all 96 patients who underwent MRI and served as the reference standard for the study. Diffusion-weighted imaging was performed in a subset of 32 patients. The process of patient selection and cohort formation is illustrated in Fig. 1. Among patients who underwent diffusion-weighted imaging (n = 32), malignant ovarian tumors were diagnosed in 22 cases (68.8%), while benign tumors were identified in 10 cases (31.2%). The demographic and histopathological characteristics of the DWI subgroup were comparable to those of the remaining MRI cohort, suggesting that the subgroup was representative of the overall study population. Morphological MRI findings Comparative analysis of conventional MRI features demonstrated significant differences between benign and malignant ovarian tumors. The presence of a solid component was observed in 68.8% of malignant tumors compared with 6.3% of benign lesions (p < 0.001). Irregular tumor margins were detected exclusively in malignant tumors (65.6%, p < 0.001), whereas benign tumors consistently demonstrated smooth and well-defined contours. Extracapsular extension was identified in 59.4% of malignant tumors and was not observed in benign lesions (p < 0.001). Ascites was present in 53.1% of malignant cases and absent in all benign tumors (p < 0.001). Regional lymphadenopathy was significantly more frequent in malignant tumors (50.0%) than in benign lesions (4.7%, p < 0.001). Peritoneal deposits were detected in 43.8% of malignant tumors and were not observed in benign tumors (p < 0.001). Cystic–solid tumor architecture was common in both groups and did not demonstrate a statistically significant association with malignancy (p = 0.56). Tumor size greater than 10 cm was observed in both benign and malignant tumors and did not reliably differentiate tumor behavior (p = 0.14). Bilateral ovarian involvement was identified exclusively in malignant tumors (12.5%, p = 0.04), indicating high specificity but limited sensitivity. Table 1 summarizes the frequency of key MRI features in benign and malignant ovarian tumors. Histological distribution Among malignant ovarian tumors, germ cell tumors represented the predominant histological group, accounting for 23 of 32 malignant tumors (71.9%). Dysgerminoma was the most common subtype, followed by immature teratoma and other germ cell malignancies. The distribution of germ cell tumor subtypes is presented in Table 2. Epithelial ovarian malignancies accounted for 8 of 32 malignant tumors (25.0%), including mucinous, endometrioid, and papillary adenocarcinomas. Benign ovarian tumors were predominantly represented by mature teratomas, followed by serous and mucinous cystadenomas, as well as fibromas and thecoma-fibromas. Diffusion-weighted imaging and ADC analysis Diffusion-weighted imaging analysis revealed marked differences between benign and malignant tumors, particularly within solid tumor components. Malignant tumors demonstrated increased signal intensity on high b-value diffusion-weighted images and corresponding reductions in apparent diffusion coefficient (ADC) values, consistent with restricted diffusion. Quantitative analysis showed that mean ADC values of the solid components were significantly lower in malignant tumors compared with benign lesions (0.8 ± 0.09 × 10⁻³ mm²/s vs. 1.2 ± 0.13 × 10⁻³ mm²/s, p = 0.019). In contrast, ADC values of cystic tumor components did not differ significantly between benign and malignant tumors (p > 0.05), reflecting free diffusion of fluid content. Table 3 presents ADC values of solid tumor components in benign and malignant ovarian tumors. Diagnostic performance of MRI and DWI Receiver operating characteristic (ROC) analysis demonstrated high diagnostic performance of MRI based on conventional morphological features, with an area under the curve (AUC) of 0.94. An optimal cutoff value of ≥ 4 MRI criteria yielded a sensitivity of 89.3%, specificity of 85.9%, and overall diagnostic accuracy of 87.0%. When diffusion-weighted imaging parameters were incorporated into the diagnostic assessment, overall diagnostic performance further improved. Combined morphological MRI and DWI analysis achieved a sensitivity of 91.0%, specificity of 88.0%, and diagnostic accuracy of 89.0%. False-negative results were primarily observed in early-stage malignant epithelial tumors lacking prominent solid components or signs of tumor spread. False-positive findings were mainly associated with benign tumors containing dense tissue elements, particularly mature teratomas, which may mimic diffusion restriction.

The present multicenter retrospective study evaluated the diagnostic value of conventional MRI features and diffusion-weighted imaging for differentiating benign and malignant ovarian tumors in children and adolescents. Our results demonstrate that MRI provides high diagnostic accuracy in the characterization of pediatric ovarian tumors, particularly when morphological features reflecting invasive tumor behavior are combined with functional diffusion-weighted imaging parameters. Several conventional MRI findings—including the presence of solid components, irregular tumor margins, extracapsular extension, ascites, lymphadenopathy, and peritoneal deposits—were strongly associated with malignant tumors. In contrast, tumor size and cystic–solid architecture alone were not reliable indicators of malignancy. These findings are consistent with previous radiological studies demonstrating that morphological MRI criteria remain the cornerstone of preoperative evaluation of adnexal masses. Earlier reports have shown that irregular margins, solid tumor components, and signs of peritoneal spread are among the most important imaging indicators of malignant ovarian tumors [7, 10]. However, several benign lesions—particularly mature teratomas and certain epithelial tumors—may also present with complex internal structures, leading to overlap between benign and malignant imaging patterns. This overlap is particularly pronounced in pediatric populations, where ovarian tumors demonstrate a broad histological spectrum and variable biological behavior. Our results confirm that relying solely on tumor size or cystic–solid architecture may lead to diagnostic uncertainty and potentially inaccurate preoperative assessment. In the present study, diffusion-weighted imaging provided valuable additional diagnostic information beyond conventional morphological MRI features. Malignant tumors demonstrated significantly lower ADC values in the solid components compared with benign lesions, reflecting higher cellularity and restricted diffusion. These findings are consistent with previously reported data in adult ovarian tumors, where ADC measurements have been shown to be a useful quantitative biomarker for differentiating benign and malignant lesions [15, 16]. Highly cellular malignant tumors typically restrict the movement of water molecules, resulting in increased signal intensity on high b-value diffusion images and reduced ADC values. The mean ADC value observed in malignant tumors in our study (0.8 × 10⁻³ mm²/s) was substantially lower than that observed in benign tumors (1.2 × 10⁻³ mm²/s), which is comparable to values reported in previous studies evaluating ovarian tumors using diffusion-weighted imaging. Although most of the available literature focuses on adult populations, our findings suggest that the diagnostic principles of diffusion restriction may also be applicable in pediatric patients. Importantly, ADC measurements should be interpreted in conjunction with morphological MRI features, as certain benign tumors containing dense tissue elements—such as mature teratomas or fibrous tumors—may demonstrate relatively low ADC values and mimic diffusion restriction. Another important observation in this study is the high diagnostic performance of MRI when combining morphological criteria with diffusion-weighted imaging. Receiver operating characteristic analysis demonstrated an area under the curve of 0.94 for morphological MRI features alone, indicating excellent diagnostic accuracy. When diffusion-weighted imaging parameters were incorporated into the analysis, overall diagnostic performance further improved, achieving a sensitivity of 91% and a specificity of 88%. These findings highlight the complementary role of functional MRI techniques in improving diagnostic confidence and reducing the risk of misclassification. Accurate preoperative differentiation between benign and malignant ovarian tumors is particularly important in pediatric and adolescent patients because fertility preservation remains a critical consideration in treatment planning. Overly aggressive surgical management of benign ovarian lesions may lead to unnecessary loss of ovarian tissue and long-term reproductive consequences. Conversely, underestimation of malignant potential may delay appropriate oncological treatment. In this context, a comprehensive MRI approach that integrates both morphological and functional imaging parameters may help guide optimal clinical decision-making and improve patient outcomes. The histological distribution observed in our cohort is consistent with previously reported epidemiological patterns of pediatric ovarian tumors. Germ cell tumors represented the predominant group of malignant ovarian tumors, accounting for more than two-thirds of cases, with dysgerminoma being the most frequent subtype. This distribution differs from adult populations, in which epithelial ovarian tumors are more common. The predominance of germ cell tumors in pediatric patients further underscores the importance of imaging techniques capable of accurately characterizing diverse tumor types with different biological behaviors. Despite the promising findings of this study, several limitations should be acknowledged. First, the retrospective design may introduce potential selection bias. Second, diffusion-weighted imaging was available only in a subset of patients because it was incorporated into the MRI protocol later during the study period. Although the clinical and histological characteristics of the DWI subgroup were comparable to those of the overall MRI cohort, the relatively small sample size may limit the statistical power of ADC analysis. Third, tumor volume measurements and volumetric assessment of solid tumor components were not systematically recorded. Finally, interobserver variability of ADC measurements was not formally assessed using statistical agreement analysis, which may influence measurement reproducibility. In addition, the placement of regions of interest for ADC measurements may introduce potential partial volume effects. Larger ROIs may lead to contamination from adjacent cystic or necrotic components, which could influence ADC values. To minimize this effect, ROIs in the present study were carefully placed within the most representative solid areas of the tumor and multiple measurements were averaged. Nevertheless, future prospective studies with standardized ROI placement protocols may further improve measurement reliability. Future research should focus on prospective multicenter studies with larger patient cohorts to further validate the diagnostic thresholds of ADC values in pediatric ovarian tumors. In addition, the integration of advanced MRI techniques—such as dynamic contrast-enhanced imaging, texture analysis, and radiomics—may provide further insights into tumor characterization and risk stratification. Overall, the results of this study support the growing role of multiparametric MRI in the evaluation of pediatric ovarian tumors. The combination of detailed morphological assessment with diffusion-weighted imaging provides a comprehensive and non-invasive diagnostic approach that may significantly improve the differentiation between benign and malignant ovarian lesions in children and adolescents. Diffusion-weighted imaging was available only in a subset of patients, which limits the statistical power of ADC analysis and suggests that these findings should be interpreted with caution.

Magnetic resonance imaging is a highly informative modality for the evaluation of ovarian tumors in children and adolescents; however, the diagnostic performance of conventional morphological MRI criteria alone may be limited because of overlap between benign and malignant lesions. MRI features reflecting invasive tumor behavior—including solid components, irregular margins, extracapsular extension, ascites, lymphadenopathy, and peritoneal deposits—demonstrated the strongest association with malignancy. In the subgroup of patients who underwent diffusion-weighted imaging, quantitative ADC assessment showed potential additional value for differentiating benign and malignant tumors. Malignant lesions demonstrated lower ADC values consistent with higher cellularity and restricted diffusion. However, because diffusion-weighted imaging was available in only a limited subset of patients, these findings should be considered preliminary. Larger prospective studies are required to validate ADC thresholds and confirm the incremental diagnostic value of diffusion-weighted imaging in the pediatric population. Data availability The datasets generated and/or analyzed during the current study are not publicly available due to institutional and ethical restrictions related to patient confidentiality but are available from the corresponding author on reasonable request.

Schultz KA et al. Ovarian tumors in children and adolescents. Pediatr Blood Cancer. 2016. Cecchetto G. Ovarian tumors in children and adolescents. J Pediatr Surg. 2014. Cass DL et al. Management of ovarian masses in children and adolescents. J Pediatr Surg. 2001. Rogers PC et al. Fertility preservation in pediatric oncology. Lancet Oncol. 2014. Servaes S et al. Imaging of pediatric ovarian neoplasms. Radiographics. 2012. Valentin L. Pattern recognition of adnexal masses by ultrasound. Ultrasound Obstet Gynecol. 2013. Thomassin-Naggara I et al. Adnexal masses: MRI imaging. Radiology. 2013. Sohaib SA et al. Characterization of adnexal masses with MRI. AJR Am J Roentgenol. 2005. Kinkel K et al. Indeterminate ovarian mass: MRI. Radiology. 2000. Forstner R et al. ESUR recommendations for MRI of ovarian tumors. Eur Radiol. 2017. Outwater EK et al. Ovarian teratomas: MR imaging. Radiology. 2001. Levy AD et al. From the archives of AFIP: ovarian neoplasms. Radiographics. 2008. Sahdev A et al. The role of MRI in ovarian cancer. Clin Radiol. 2007. Koh DM, Collins DJ. Diffusion-weighted MRI in oncology. Eur Radiol. 2007. Thomassin-Naggara I et al. Diffusion-weighted MRI for ovarian tumors. Radiology. 2011. Fujii S et al. Diagnostic accuracy of ADC values in ovarian tumors. AJR. 2008. Kyriazi S et al. Diffusion-weighted imaging of ovarian cancer. Eur Radiol. 2010. Ghosh P et al. Pediatric pelvic MRI: challenges and pitfalls. Pediatr Radiol. 2019. Brown J et al. Malignant ovarian tumors in children. Gynecol Oncol. 2014. Li HM et al. Added value of DWI in ovarian tumors. Eur J Radiol. 2015. Funding The authors received no specific funding for this study. Author information Authors and Affiliations Contributions G.Y. and M.K. conceived and designed the study.G.Y., U.U., L.S., and M.A. contributed to data collection and image analysis.M.K. performed the statistical analysis and drafted the manuscript.All authors critically revised the manuscript and approved the final version. Corresponding author Ethics declarations Ethics approval and consent to participate The study was approved by the Ethics Committee of the Tashkent Pediatric Medical Institute. Due to the retrospective observational design of the study and the use of anonymized clinical and imaging data, the requirement for informed consent was waived by the Ethics Committee. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Additional information Publisher’s Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rights and permissions Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. About this article Cite this article Yusupaliyeva, G., Umarova, U., Khayitboeva, M. et al. MRI evaluation of pediatric ovarian tumors: morphological features and preliminary assessment of diffusion-weighted imaging. BMC Pediatr 26, 409 (2026). https://doi.org/10.1186/s12887-026-06783-w Received: Accepted: Published: Version of record: DOI: https://doi.org/10.1186/s12887-026-06783-w