Diagnostic Accuracy of Transvaginal Ultrasonography Versus MRI in Early Detection of Adenomyosis

Background: Adenomyosis is a common gynecological condition characterized by the invasion of endometrial glands and stroma into the myometrium. Early and accurate diagnosis remains challenging due to overlapping symptomatology with other uterine pathologies. Both transvaginal ultrasonography (TVS) and ma gnetic resonance imaging (MRI) are widely utilized non -invasive diagnostic modalities, yet comparative evidence regarding their accuracy in early-stage adenomyosis detection remains limited.

A prospective cross -sectional diagnostic accuracy study was conducted on 186 premenopausal women presenting with symptoms suggestive of adenomyosis. All participants underwent both TVS and pelvic MRI prior to hysterectomy. Histopathological analysis of hysterectomy specimens served as the definitive diagnostic reference. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall diagnostic accuracy were calculated for both modalities.

Histopathology confirmed adenomyosis in 124 of 186 patients (66.7%). MRI de monstrated superior sensitivity (91.9% vs. 83.1%, p = 0.034), specificity (90.3% vs. 79.0%, p = 0.041), and overall diagnostic accuracy (91.4% vs. 81.7%, p = 0.012) compared to TVS. The area under the receiver operating characteristic curve (AUC) was significantly higher for MRI (0.941) than for TVS (0.862, p = 0.008). MRI showed particular superiority in detecting focal adenomyosis (sensitivity 89.5% vs. 68.4%, p = 0.018).

MRI demonstrates significantly higher diagnostic accuracy than TVS in th e early detection of adenomyosis, particularly for focal subtypes. However, TVS remains a valuable and accessible first -line screening tool.

Adenomyosis, Transvaginal Ultrasonography , Magnetic Resonance Imaging , Diagnostic Accuracy, Early Detection, Histopathology 1. Introduction Adenomyosis is a benign gynecological disorder defined by the ectopic presence of endometrial glands and stroma within the myometrium, accompanied by surrounding smooth muscle hyperplasia and hypertrophy [1]. The condi tion affects an estimated 20 -35% of women of reproductive age, although prevalence rates vary considerably depending on the diagnostic criteria and population studied [2]. Clinically, adenomyosis manifests with dysmenorrhea, menorrhagia, chronic pelvic pai n, and subfertility, significantly impacting quality of life and reproductive outcomes [3]. Historically, the definitive diagnosis of adenomyosis required histopathological examination of hysterectomy specimens, rendering preoperative diagnosis inherently challenging [4]. The advent of advanced imaging modalities has transformed the diagnostic landscape, enabling non - invasive identification of adenomyosis prior to surgical intervention. Transvaginal ultrasonography and magnetic resonance imaging have emerge d as the two principal imaging techniques for this purpose [5]. TVS is widely accessible, cost -effective, and serves as the first -line imaging modality in gynecological practice. Characteristic sonographic features of adenomyosis include heterogeneous myom etrial echotexture, myometrial cysts, asymmetric myometrial thickening, subendometrial echogenic linear striations, and a poorly defined endometrial -myometrial junction [6]. However, the diagnostic performance of TVS is operator -dependent and may be limited in cases of coexistent uterine pathology such as leiomyomas [7]. MRI offers superior soft tissue contrast resolution and multiplanar imaging capability, facilitating detailed evaluation of the junctional zone (JZ) and myometrial architecture. A junctional zone thickness exceeding 12 mm is considered the most reliable MRI criterion for International Journal of Clinical Obstetrics and Gynaecology https://www.gynaecologyjournal.com ~ 1217 ~ adenomyosis diagnosis [8]. Several studies have reported high sensitivity and specificity for MRI in adenomyosis detection, with values ranging from 78% to 93% and 67% to 99 %, respectively [9]. Despite the growing body of literature on both modalities, comparative studies evaluating their diagnostic performance specifically in early -stage adenomyosis remain sparse. Early detection is clinically significant because timely intervention can preserve fertility and improve symptom management [10]. Furthermore, existing studies have yielded heterogeneous results, partly attributable to differences in study design, diagnostic criteria, and patient populations [11]. A recent meta - analysis highlighted the need for well -designed prospective studies comparing TVS and MRI using standardized diagnostic criteria and histopathological confirmation [12]. The aim of this study was to prospectively compare the diagnostic accuracy of TVS and MRI in the early detection of adenomyosis, utilizing histopathological analysis of hysterectomy specimens as the gold standard reference, and to evaluate the performance of each modality across different subtypes of the disease. 2. Materials and Methods Study Design and Setting This prospective cross -sectional diagnostic accuracy study was conducted at the Department of Obstetrics and Gynecology. Study Population: A total of 186 premenopausal women aged 30-50 years who presented with symptoms suggestive of adenomyosis (dysmenorrhea, menorrhagia, chronic pelvic pain, or dyspareunia) and were scheduled for hysterectomy for various benign gynecological indications were enrolled consecutively. Exclusion criteria included postmenopausal status, prior uterine surgery other than cesarean section, known uterine malignancy, contraindications to MRI (e.g., metallic implants, claustrophobia), hormonal therapy within the preceding three months, and pregnancy. Imaging Protocol All participants underwent TVS followed by pelvi c MRI within a two-week interval prior to hysterectomy. TVS was performed during the early proliferative phase (cycle days 5 -10) using a high-resolution endovaginal transducer (5 -9 MHz) on a GE Voluson E10 ultrasound system. Examinations were conducted by two experienced sonologists (each with >10 years of gynecological ultrasound experience) who were blinded to MRI findings. Standardized TVS diagnostic criteria for adenomyosis included heterogeneous myometrial echotexture, myometrial cysts, subendometrial linear striations, asymmetric myometrial thickening, and fan-shaped shadowing. Pelvic MRI was performed using a 3.0 -Tesla scanner (Siemens Magnetom Prisma) with a phased-array pelvic coil. The imaging protocol included T2-weighted turbo spin -echo sequences in sagittal, coronal, and axial planes; T1-weighted sequences; and diffusion-weighted imaging. Two experienced radiologists (>8 years of pelvic MRI experience), blinded to TVS results and clinical data, independently evaluated the MRI images. MRI diagnostic criteria included JZ thickness ≥12 mm, JZ maximum - to-minimum thickness ratio >2.2, presence of high -signal foci within the myometrium on T2-weighted images, and ill -defined low-signal myometrial masses. Histopathological Examination: Hysterectomy specimens were processed according to standard protocols. Multiple systematic sections (minimum of four per specimen) were obtained from representative areas. Histopathological diagnosis of adenomyosis was established when endometrial glands and stroma were ident ified at a depth of ≥2.5 mm from the endometrial-myometrial junction. A senior gynecological pathologist, blinded to imaging results, rendered all diagnoses. Adenomyosis was further classified as diffuse or focal based on histological distribution. Statistical Analysis Sample size was calculated assuming a sensitivity of 85% for TVS and 92% for MRI with an alpha error of 0.05 and power of 80%, yielding a minimum requirement of 170 subjects. Continuous variables were expressed as mean ± standard deviation, a nd categorical variables were presented as frequencies and percentages. Sensitivity, specificity, PPV, NPV, and overall accuracy were calculated for each modality with 95% confidence intervals. McNemar's test was used to compare paired proportions. ROC cur ve analysis was performed, and AUC values were compared using the DeLong method. Inter - observer agreement was assessed using Cohen's kappa coefficient. A p -value <0.05 was considered statistically significant. All analyses were performed using SPSS version 28.0 and MedCalc version 20.1. 3. Results Demographic and Clinical Characteristics The mean age of the 186 enrolled participants was 41.3 ± 5.7 years. The most common presenting symptom was menorrhagia (72.0%), followed by dysmenorrhea (65.6%) and chroni c pelvic pain (48.9%). Histopathological examination confirmed adenomyosis in 124 patients (66.7%), of whom 86 (69.4%) had diffuse adenomyosis and 38 (30.6%) had focal adenomyosis (Table 1). Table 1: Demographic and Clinical Characteristics of the Study Population (N = 186) Variable Value Age (years), mean ± SD 41.3 ± 5.7 BMI (kg/m²), mean ± SD 26.8 ± 4.2 Parity, median (IQR) 2 (1-3) Menorrhagia, n (%) 134 (72.0%) Dysmenorrhea, n (%) 122 (65.6%) Chronic pelvic pain, n (%) 91 (48.9%) Dyspareunia, n (%) 54 (29.0%) Uterine volume (cm³), mean ± SD 142.6 ± 58.3 Histologically confirmed adenomyosis, n (%) 124 (66.7%) Diffuse adenomyosis, n (%) 86 (69.4%) Focal adenomyosis, n (%) 38 (30.6%) Coexistent leiomyomas, n (%) 47 (25.3%) Diagnostic Performance of TVS and MRI TVS correctly identified adenomyosis in 103 of 124 histologically confirmed cases (sensitivity 83.1%) and correctly excluded the condition in 49 of 62 non -adenomyosis cases (specificity 79.0%). MRI correctly identified 114 of 124 confirmed cases (sensitivity 91.9%) and correctly excluded the condition in 56 of 62 cases (specificity 90.3%). The overall diagnostic accuracy was 81.7% for TVS and 91.4% for MRI (p = 0.012). The AUC was 0.862 (95% CI: 0.806 -0.918) for TVS and 0.941 (95% CI: 0.903-0.979) for MRI (p = 0.008) (Table 2). International Journal of Clinical Obstetrics and Gynaecology https://www.gynaecologyjournal.com ~ 1218 ~ Table 2: Diagnostic Performance of TVS and MRI for Adenomyosis Detection (N = 186) Parameter TVS (95% CI) MRI (95% CI) p-value True Positives 103 114 — True Negatives 49 56 — False Positives 13 6 — False Negatives 21 10 — Sensitivity (%) 83.1 (75.4-89.1) 91.9 (85.7-96.0) 0.034 Specificity (%) 79.0 (66.8-88.3) 90.3 (80.1-96.4) 0.041 PPV (%) 88.8 (81.6-93.8) 95.0 (89.3-98.1) 0.068 NPV (%) 70.0 (57.9-80.4) 84.8 (73.0-92.8) 0.027 Overall Accuracy (%) 81.7 (75.4-87.0) 91.4 (86.4-95.0) 0.012 AUC 0.862 (0.806-0.918) 0.941 (0.903-0.979) 0.008 Subtype Analysis and Inter-observer Agreement Subtype analysis revealed that MRI demonstrated markedly superior sensitivity for focal adenomyosis compared to TVS (89.5% vs. 68.4%, p = 0.018), while the difference was less pronounced for diffuse adenomyosis (93.0% vs. 89.5%, p = 0.312). Inter -observer agreement was substantial for TVS (κ = 0.72) and almost perfect for MRI (κ = 0.89) (Table 3). Table 3: Diagnostic Performance by Adenomyosis Subtype and Inter- observer Agreement Parameter TVS MRI p-value Diffuse adenomyosis (n = 86) Sensitivity (%) 89.5 93.0 0.312 Specificity (%) 79.0 90.3 0.041 Focal adenomyosis (n = 38) Sensitivity (%) 68.4 89.5 0.018 Specificity (%) 79.0 90.3 0.041 Coexistent leiomyomas (n = 47) Sensitivity (%) 74.3 88.6 0.029 Specificity (%) 75.0 91.7 0.035 Inter-observer agreement (κ) 0.72 0.89 — Agreement classification Substantial Almost perfect — In cases with coexistent leiomyomas (n = 47), MRI maintained significantly higher sensitivity (88.6% vs. 74.3%, p = 0.029) and specificity (91.7% vs. 75.0%, p = 0.035) compared to TVS. 4. Discussion The present study demonstrates that MRI possesses significantly superior diagnost ic accuracy compared to TVS in the early detection of adenomyosis, with an overall accuracy of 91.4% versus 81.7%. These findings are consistent with previous investigations that have reported the enhanced capability of MRI in characterizing myometrial pat hology [13]. The higher spatial and contrast resolution of MRI facilitates precise evaluation of the junctional zone, which is the anatomical hallmark affected in adenomyosis [14]. The sensitivity of TVS observed in our study (83.1%) aligns closely with th e pooled estimates reported in a comprehensive meta-analysis by Stable and colleagues, who documented a pooled sensitivity of 82.5% and specificity of 84.7% for TVS in adenomyosis diagnosis [15]. Similarly, our MRI sensitivity of 91.9% is concordant with t he findings of Champaneria et al ., who reported a pooled MRI sensitivity of 90.0% in their systematic review [16]. A particularly noteworthy finding of this study is the significantly superior performance of MRI in detecting focal adenomyosis (sensitivity 89.5% vs. 68.4%, p = 0.018). Focal adenomyosis, or adenomyoma, presents a well -recognized diagnostic challenge on ultrasonography due to its morphological resemblance to leiomyomas [17]. The ability of MRI to delineate ill-defined borders, identify high-signal foci on T2-weighted sequences, and assess the junctional zone relationship provides a distinct advantage in differentiating focal adenomyosis from leiomyomas [18]. The diagnostic challenge posed by coexistent leiomyomas was further corroborated in our subgroup analysis, where TVS sensitivity decreased to 74.3% in the presence of concomitant fibroids compared to 83.1% overall. MRI maintained robust performance (88.6%) in this clinically relevant scenario. This finding substantiates the observations of D ueholm and Lundorf, who emphasized the limitations of TVS when adenomyosis coexists with leiomyomas [19]. Inter-observer agreement was substantially higher for MRI (κ = 0.89) compared to TVS (κ = 0.72), reflecting the greater objectivity and reproducibilit y of MRI interpretation. This finding is clinically relevant, as the operator-dependent nature of ultrasonography has been consistently identified as a limitation in adenomyosis diagnosis [20]. Nonetheless, it should be acknowledged that the experience lev el of the sonologists may substantially influence TVS accuracy, and centers with specialized expertise in gynecological ultrasound may achieve performance levels closer to those of MRI [21]. Despite the statistical superiority of MRI, the clinical utility of TVS as a first -line screening modality should not be underestimated. TVS is readily available, less expensive, well - tolerated by patients, and capable of real -time dynamic assessment. The concept of employing TVS as an initial screening tool with select ive MRI referral for equivocal cases has been advocated by several authors and appears to represent a cost-effective diagnostic strategy [22]. Furthermore, recent advances in sonographic techniques, including three - dimensional TVS and elastography, hold pr omise for improving the diagnostic accuracy of ultrasound-based approaches [23]. This study possesses several methodological strengths, including its prospective design, use of histopathological confirmation as the reference standard, blinding of imaging i nterpreters, and standardized diagnostic criteria. However, certain limitations warrant acknowledgment. The study population was restricted to women undergoing hysterectomy, introducing potential selection bias toward more severe disease. Additionally, the single-center design may limit generalizability. The exclusion of women receiving hormonal therapy, while methodologically sound, may not reflect routine clinical practice where many patients present while on medical management [24]. 5. Conclusion This p rospective diagnostic accuracy study demonstrates that MRI is significantly superior to TVS in the early detection of adenomyosis, exhibiting higher sensitivity, specificity, and overall diagnostic accuracy. The advantage of MRI is particularly pronounced in the detection of focal adenomyosis and in cases complicated by coexistent leiomyomas. MRI also demonstrates higher inter -observer reproducibility, supporting its role as the preferred confirmatory imaging modality. Nevertheless, TVS remains a valuable, accessible, and cost - effective first -line screening tool in clinical practice. A tiered diagnostic approach utilizing TVS for initial assessment with selective MRI referral for inconclusive or complex cases is recommended to optimize diagnostic accuracy wh ile maintaining clinical efficiency. Future multicenter studies incorporating fertility -sparing surgical outcomes and advanced ultrasound techniques are warranted to further refine diagnostic algorithms for adenomyosis. Conflict of Interest Not available. International Journal of Clinical Obstetrics and Gynaecology https://www.gynaecologyjournal.com ~ 1219 ~ Financial Support Not available.

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