Comparison of three-tesla magnetic resonance imaging with pathology in detecting deep myometrial invasion in endometrial cancer and revealing causes of discrepancy

PURPOSE: To evaluate the accuracy of three-tesla (3T) magnetic resonance imaging (MRI) in determining deep myometrial invasion (DMI) in endometrial cancer (EC) cases and to reveal possible causes of discrepancy. METHODS: Patients with EC who underwent preoperative pelvic MRI examination at a tertiary hospital were independently and blindly reviewed for DMI by two radiologists with differing levels of expertise. On MRI, the invasion of the endometrial mass into the myometrium was defined as superficial or deep (<50% or ≥50%) and was compared with the gold standard pathology reports, evaluated using the same criteria. Cases with discrepancies between MRI and pathology were re-evaluated, and the causes of the discrepancies were identified. RESULTS: A total of 226 patients were included. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of MRI in detecting DMI were calculated as 77%, 93%, 84%, 88%, and 87%, respectively. In cases where radiology and pathology results were incompatible, expansile masses were found in 38%, myomas located near the lesion in 27%, masses located in the uterine horn in 21%, and in 14%, a specific cause explaining the error could not be identified. CONCLUSION: MRI is the definitive diagnostic method for determining DMI. Awareness of these causes of discrepancy in MRI reporting can increase the value of the examination and contribute to patient management. CLINICAL SIGNIFICANCE: This study highlights that 3T MRI has a high accuracy (87%) in detecting DMI in EC and demonstrates that analyzing misinterpretations can enhance reliability in patient management.