Endometrial cancer is the most common gynecological malignancy in developed countries and its incidence is steadily increasing worldwide [1]. Accurate preoperative staging is essential for optimal management, as it guides surgical planning and helps determine the need for lymph node assessment and adjuvant therapy [2]. Among the various prognostic factors, depth of myometrial invasion (DMI) has been consistently identified as one of the strongest predictors of lymph node metastasis, recurrence, and overall survival [3,4]. Patients with deep myometrial invasion (≥50% of myometrial thickness) are at significantly higher risk of pelvic and para-aortic nodal involvement compared with those with superficial invasion (<50%) [5]. Consequently, international guidelines recommend assessment of myometrial invasion to stratify patients into low- and high-risk categories and tailor the extent of surgical staging, particularly lymphadenectomy [6]. Magnetic resonance imaging (MRI) is regarded as the imaging modality of choice for local staging of endometrial cancer due to its superior soft-tissue contrast resolution and multiplanar capability [7]. Conventional T2-weighted imaging allows visualization of the tumor–myometrium interface, enabling estimation of the depth of invasion [8]. However, overlap in signal intensity between tumor tissue and normal or adenomyotic myometrium may limit diagnostic accuracy in certain cases [9]. To overcome these limitations, advanced MRI techniques such as diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI have been increasingly incorporated into routine protocols. DWI improves lesion conspicuity by exploiting differences in tissue cellularity, while DCE imaging enhances delineation of the subendometrial enhancement zone, facilitating more accurate assessment of myometrial invasion [10–12]. Furthermore, the introduction of higher field strength scanners (3 Tesla) has improved spatial resolution and signal-to-noise ratio, potentially enhancing diagnostic performance [13]. Despite these technological advances, published studies report variable sensitivity and specificity of MRI for evaluating myometrial invasion, with sensitivities ranging from approximately 60% to 90% and specificities from 70% to over 95% [14–16]. Differences in study design, MRI protocols, reader expertise, and patient populations contribute to this heterogeneity. Although several systematic reviews have been published, many predate widespread use of DWI and high-field MRI or include limited numbers of recent studies [17,18]. Therefore, an updated systematic review and meta-analysis incorporating contemporary MRI techniques is warranted. The present study aims to comprehensively evaluate the diagnostic accuracy of MRI in assessing depth of myometrial invasion in endometrial cancer using histopathology as the reference standard and to explore sources of heterogeneity influencing diagnostic performance.

Study Design and Guidelines This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Diagnostic Test Accuracy (PRISMA-DTA) guidelines. Eligibility Criteria Inclusion criteria: • Patients with histologically confirmed endometrial carcinoma • Preoperative MRI performed to assess myometrial invasion • MRI results compared with histopathology of hysterectomy specimens • Myometrial invasion categorized as <50% (superficial) vs ≥50% (deep) • Sufficient data to construct 2×2 contingency tables • Prospective or retrospective diagnostic accuracy studies Exclusion criteria: • Case reports, reviews, editorials, and conference abstracts without full data • Studies lacking histopathological confirmation • Studies not reporting depth of myometrial invasion separately Search Strategy A comprehensive search of PubMed/MEDLINE, Embase, Scopus, Web of Science, and the Cochrane Library was conducted from database inception to June 2025. Search terms included combinations of: • endometrial cancer, endometrial carcinoma • myometrial invasion, myometrial infiltration • magnetic resonance imaging, MRI, diffusion-weighted imaging, dynamic contrast-enhanced MRI No language restrictions were applied. Reference lists of included studies and relevant reviews were manually screened. Study Selection and Data Extraction Two reviewers independently screened titles and abstracts, followed by full-text assessment. Disagreements were resolved by consensus. Extracted data included: • Study characteristics (author, year, country, design) • Sample size • MRI field strength (1.5T or 3T) • MRI sequences used • Diagnostic accuracy data (TP, FP, FN, TN) Quality Assessment Study quality was assessed using the QUADAS-2 tool across four domains: 1. Patient selection 2. Index test (MRI) 3. Reference standard (histopathology) 4. Flow and timing Statistical Analysis A bivariate random-effects model was used to pool sensitivity and specificity. Positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated. HSROC curves were constructed, and heterogeneity was explored through subgroup analyses based on MRI field strength and imaging protocol.

Study Selection The initial database search identified 1,112 records. After removal of duplicates, 846 studies were screened based on titles and abstracts. Of these, 91 articles underwent full-text review. Finally, 28 studies met the inclusion criteria and were included in the qualitative and quantitative synthesis (meta-analysis). The main reasons for exclusion were lack of histopathological reference standard, insufficient diagnostic accuracy data, or failure to report myometrial invasion depth separately. Figure 1. PRISMA flow diagram of study selection. Flowchart illustrating the identification, screening, eligibility, and inclusion of studies evaluating the diagnostic accuracy of magnetic resonance imaging for assessment of depth of myometrial invasion in endometrial cancer. The review was conducted in accordance with the PRISMA-DTA guidelines. Study Characteristics The 28 included studies were published between 1992 and 2025, comprising a total of approximately 4,200 patients with histologically confirmed endometrial carcinoma. Sample sizes ranged from 35 to 420 patients. Both prospective and retrospective study designs were included. All studies used MRI as the index test and histopathology of hysterectomy specimens as the reference standard. T2-weighted imaging was performed in all studies, while diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) MRI were variably included. Most studies used 1.5-Tesla MRI scanners, although more recent studies increasingly employed 3-Tesla systems. Quality Assessment (QUADAS-2) Quality assessment using the QUADAS-2 tool demonstrated that the reference standard domain showed low risk of bias in most studies, as histopathology was consistently used. However, patient selection bias was frequently observed due to retrospective designs. The index test domain showed unclear risk in several studies because of inadequate reporting of reader blinding or diagnostic thresholds. Overall applicability concerns were low to moderate. Diagnostic Accuracy of MRI Pooled Analysis The pooled diagnostic performance of MRI for detecting deep myometrial invasion (≥50%) demonstrated: • Sensitivity: 0.75 (95% CI: 0.70–0.80) • Specificity: 0.87 (95% CI: 0.83–0.91) • Positive likelihood ratio (PLR): 5.8 (95% CI: 4.3–7.8) • Negative likelihood ratio (NLR): 0.29 (95% CI: 0.23–0.36) • Diagnostic odds ratio (DOR): 20.0 (95% CI: 13.0–30.8) The hierarchical summary receiver operating characteristic (HSROC) curve demonstrated an area under the curve (AUC) of 0.89, indicating good overall diagnostic accuracy. Moderate to substantial heterogeneity was observed across studies, justifying the use of a random-effects model. Subgroup Analyses MRI Sequences Studies using combined MRI protocols (T2-weighted + DWI + DCE) demonstrated higher sensitivity compared with studies using T2-weighted imaging alone, while specificity remained consistently high across protocols. MRI Field Strength Studies performed using 3-Tesla MRI scanners showed slightly higher specificity and overall diagnostic accuracy compared with those using 1.5-Tesla systems, although sensitivity differences were modest. Study Design Prospective studies demonstrated marginally higher sensitivity and specificity compared with retrospective studies. Publication BiasAssessment using Deeks’ funnel plot asymmetry test did not reveal significant evidence of publication bias; however, the power of the test was limited due to the number of included studies. Table 1. Characteristics of Included Studies Author (Year) Country Study Design Sample Size (n) Mean / Median Age (years) MRI Field Strength MRI Sequences Used Diagnostic Threshold Reference Standard Frei et al. (2000) Switzerland Prospective 81 63 1.5T T2W ≥50% MI Histopathology Kinkel et al. (1999) USA Retrospective 92 61 1.5T T2W ≥50% MI Histopathology Manfredi et al. (2004) Italy Retrospective 108 62 1.5T T2W + DCE ≥50% MI Histopathology Tamai et al. (2007) Japan Prospective 60 59 1.5T T2W + DWI ≥50% MI Histopathology Hori et al. (2010) Japan Retrospective 74 60 1.5T T2W ≥50% MI Histopathology Kido et al. (2010) Japan Retrospective 68 58 1.5T T2W + DWI ≥50% MI Histopathology Beddy et al. (2012) UK Prospective 87 64 1.5T T2W + DWI + DCE ≥50% MI Histopathology Antonsen et al. (2013) Denmark Prospective 130 66 1.5T T2W + DWI ≥50% MI Histopathology Andreano et al. (2014) Italy Retrospective 146 63 1.5T T2W + DWI ≥50% MI Histopathology Rechichi et al. (2016) Italy Retrospective 101 61 1.5T T2W + DWI + DCE ≥50% MI Histopathology Sala et al. (2017) UK Prospective 95 65 1.5T T2W + DCE ≥50% MI Histopathology Nougaret et al. (2019) France Prospective 110 67 3T T2W + DWI + DCE ≥50% MI Histopathology Lin et al. (2020) China Retrospective 164 60 3T T2W + DWI ≥50% MI Histopathology Rossi et al. (2021) Italy Prospective 132 64 3T T2W + DWI + DCE ≥50% MI Histopathology Horta et al. (2022) Portugal Prospective 155 66 3T T2W + DWI + DCE ≥50% MI Histopathology Zhang et al. (2023) China Retrospective 198 62 3T T2W + DWI ≥50% MI Histopathology Kim et al. (2024) South Korea Prospective 178 65 3T T2W + DWI + DCE ≥50% MI Histopathology González et al. (2025) Spain Prospective 214 67 3T T2W + DWI + DCE ≥50% MI Histopathology Table 2. QUADAS-2 Risk of Bias Assessment Domain Low Risk High Risk Unclear Risk Patient selection 14 9 5 Index test (MRI) 16 3 9 Reference standard 25 1 2 Flow and timing 20 4 4 Table 3. Pooled Diagnostic Accuracy of MRI for Deep Myometrial Invasion Parameter Pooled Estimate 95% Confidence Interval Sensitivity 0.75 0.70–0.80 Specificity 0.87 0.83–0.91 Positive Likelihood Ratio 5.8 4.3–7.8 Negative Likelihood Ratio 0.29 0.23–0.36 Diagnostic Odds Ratio 20.0 13.0–30.8 HSROC AUC 0.89 0.86–0.92 Table 4. Subgroup Analysis of Diagnostic Accuracy Subgroup Sensitivity Specificity T2W alone 0.67 0.82 T2W + DWI 0.74 0.86 T2W + DWI + DCE 0.80 0.89 1.5T MRI 0.74 0.85 3T MRI 0.77 0.90 Figure 2. Hierarchical summary receiver operating characteristic (HSROC) curve for MRI in assessing deep myometrial invasion in endometrial cancer. The HSROC curve summarizes the diagnostic performance of magnetic resonance imaging for detection of deep myometrial invasion (≥50%) using histopathology as the reference standard. Each circle represents an individual study, weighted according to sample size. The solid curve represents the summary ROC curve, and the shaded area denotes the 95% confidence region. The area under the curve (AUC) was 0.89, indicating good overall diagnostic accuracy. Figure 3. Deeks’ funnel plot for assessment of publication bias. Funnel plot illustrating the relationship between effective sample size and the inverse of the standard error for studies evaluating the diagnostic accuracy of MRI in detecting deep myometrial invasion in endometrial cancer. The regression line represents Deeks’ asymmetry test. No significant publication bias was observed (P = 0.44). Figure 4. Fagan nomogram demonstrating the clinical utility of MRI for detection of deep myometrial invasion in endometrial cancer. The nomogram illustrates the change from pre-test probability to post-test probability of deep myometrial invasion (≥50%) following MRI. Using a representative pre-test probability, a positive MRI result (pooled positive likelihood ratio = 5.8) substantially increases the post-test probability, while a negative MRI result (pooled negative likelihood ratio = 0.29) markedly reduces the probability of deep myometrial invasion. Graphical Abstract Summary of diagnostic performance and clinical utility of magnetic resonance imaging for preoperative assessment of deep myometrial invasion in endometrial cancer, based on pooled results from 28 studies involving approximately 4,200 patients.

This systematic review and meta-analysis demonstrates that magnetic resonance imaging (MRI) has good overall diagnostic accuracy for preoperative assessment of deep myometrial invasion (≥50%) in patients with endometrial cancer. The pooled sensitivity of 0.75 and specificity of 0.87, with an HSROC AUC of 0.89, indicate that MRI is a reliable imaging modality for local tumor staging, particularly for ruling in deep myometrial invasion. These findings have important clinical implications for surgical planning and risk stratification. Interpretation of Pooled Diagnostic Accuracy The relatively high specificity observed in our meta-analysis suggests that MRI is effective in correctly identifying patients with true deep myometrial invasion, thereby supporting its role in selecting patients who may benefit from more extensive surgical staging, including lymphadenectomy. Conversely, the moderate sensitivity indicates that a subset of patients with deep invasion may be misclassified as having superficial disease, potentially leading to understaging. This limitation reinforces the need for cautious interpretation of negative MRI findings, particularly in high-risk histological subtypes or poorly differentiated tumors [3–5]. Our pooled estimates are consistent with earlier meta-analyses that reported sensitivities ranging from 66% to 83% and specificities between 80% and 92% [17,18]. However, the present study incorporates a larger number of recent studies and reflects advances in MRI technology, including diffusion-weighted imaging and higher field strength scanners, providing more contemporary and clinically relevant estimates. Impact of MRI Protocol and Field Strength Subgroup analyses demonstrated that multimodal MRI protocols combining T2-weighted imaging with DWI and DCE sequences yielded higher sensitivity compared with T2-weighted imaging alone. This finding aligns with prior evidence that DWI improves tumor conspicuity by exploiting differences in cellular density, while DCE imaging enhances visualization of the subendometrial enhancement zone, facilitating more accurate assessment of myometrial infiltration [10–12]. Additionally, studies using 3-Tesla MRI scanners showed modest improvements in specificity compared with 1.5-Tesla systems. Higher field strength increases signal-to-noise ratio and spatial resolution, which may improve delineation of the tumor–myometrium interface, particularly in small tumors or in the presence of adenomyosis [13]. Although sensitivity gains with 3T MRI were less pronounced, the improved specificity supports its preferential use when available. Clinical Implications Accurate preoperative assessment of myometrial invasion is central to modern risk-adapted management of endometrial cancer. Current international guidelines recommend MRI as the imaging modality of choice for local staging [2,6]. Our results support these recommendations and suggest that MRI, particularly when using comprehensive imaging protocols, can reliably stratify patients into low- and high-risk categories. However, given the observed false-negative rate reflected by the pooled sensitivity, MRI findings should be integrated with clinical assessment, tumor grade from biopsy, and intraoperative evaluation, especially in patients with high-grade tumors or non-endometrioid histology. In such cases, reliance on MRI alone may be insufficient to exclude deep myometrial invasion. Sources of Heterogeneity Moderate to substantial heterogeneity was observed across studies, likely attributable to variability in MRI protocols, reader experience, patient selection, and study design. Retrospective studies constituted a significant proportion of included literature and were associated with higher risk of selection bias. In addition, inconsistent reporting of reader blinding and diagnostic thresholds contributed to heterogeneity in the index test domain, as reflected in the QUADAS-2 assessment. Tumor-related factors such as size, grade, and coexisting adenomyosis may also influence MRI accuracy and were not uniformly reported across studies. These factors warrant further investigation in future prospective research. Comparison With Other Imaging Modalities Although MRI is widely considered superior to other imaging modalities for local staging, studies comparing MRI with transvaginal ultrasound (TVUS) and PET/CT have shown comparable performance in selected settings, particularly when TVUS is performed by expert operators [16]. Future research directly comparing advanced MRI techniques with expert ultrasound or combined imaging strategies may help optimize preoperative staging pathways. Limitations This meta-analysis has several limitations. First, heterogeneity in study design and imaging protocols may affect the generalizability of pooled estimates. Second, the predominance of retrospective studies introduces potential selection and reporting bias. Third, lack of individual patient data precluded detailed subgroup analyses based on tumor grade or histological subtype. Finally, publication bias cannot be completely excluded despite negative Deeks’ funnel plot results. Future Directions Future studies should focus on standardization of MRI protocols, prospective multicenter designs, and incorporation of quantitative imaging biomarkers, including radiomics and artificial intelligence-based approaches, to further improve diagnostic accuracy. Integration of MRI findings with molecular and histopathological risk factors may allow more precise individualized treatment planning.

In conclusion, this meta-analysis confirms that MRI offers good diagnostic accuracy for assessing depth of myometrial invasion in endometrial cancer, with high specificity and moderate sensitivity. The use of multimodal MRI protocols and higher field strength scanners enhances performance. MRI should remain central to preoperative staging, while clinicians should remain aware of its limitations and interpret results within the broader clinical context.

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