Diagnostic Accuracy of Diffusion-Weighted MRI in Diagnosing Malignant Ovarian Lesions

Abstract

Background:
Accurate preoperative differentiation between benign and malignant ovarian lesions is essential for appropriate patient management and timely referral to gynecologic oncology services. Ultrasonography is commonly used as the initial imaging modality; however, many adnexal masses remain indeterminate. Magnetic resonance imaging (MRI), particularly diffusion-weighted imaging (DWI), provides functional information based on water molecule diffusion and may improve lesion characterization.

Objective:
To determine the diagnostic accuracy of diffusion-weighted magnetic resonance imaging in distinguishing benign from malignant ovarian lesions using histopathology as the reference standard.

Methods:
This cross-sectional diagnostic validation study was conducted at Recep Tayyip Erdoğan Hospital (RTEH), Muzaffargarh, over a six-month period from January 2026 to June 2026. A total of 120 female patients aged 18–70 years with suspected ovarian masses on ultrasonography underwent pelvic MRI including diffusion-weighted sequences and apparent diffusion coefficient (ADC) mapping. Lesions were categorized as malignant or benign based on morphological features and diffusion restriction. All patients subsequently underwent surgical removal of the mass, and histopathological examination served as the gold standard. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were calculated.

Results:
Histopathology confirmed malignancy in 48 (40%) patients and benign lesions in 72 (60%) patients. Diffusion-weighted MRI demonstrated true positive findings in 43 cases, true negatives in 63 cases, false positives in 9 cases, and false negatives in 5 cases. The sensitivity of DWI-MRI was 89.6%, specificity 87.5%, positive predictive value 82.7%, negative predictive value 92.6%, and overall diagnostic accuracy 88.3%. Malignant lesions showed significantly lower ADC values compared with benign lesions.

Conclusion:
Diffusion-weighted MRI is a reliable, non-invasive imaging technique for differentiating benign from malignant ovarian lesions. Incorporation of DWI and ADC measurement into routine pelvic MRI protocols can enhance diagnostic confidence, guide surgical planning, and reduce unnecessary radical surgery in benign conditions.