Utility of Diffusion-Weighted MRI with ADC Values in the Characterisation of Endometrial Lesions: A Prospective Cohort Study

Introduction: Endometrial lesions are a diagnostic dilemma for both radiologists, as well as, gynecologists. Characterising these lesions is crucial for effective management. The Apparent Diffusion Coefficient (ADC) reflects the molecular translational movement of water molecules. Malignant tumours, with higher cellularity than benign tumours, exhibit decreased ADC values compared to benign lesions. Aim: This study aimed to evaluate the diagnostic accuracy of ADC in conjunction with Diffusion-weighted Images (DWI) for differentiating malignant and benign endometrial lesions. Materials and Methods: A prospective cohort study was conducted at the Outpatient Department (OPD) of Radiodiagnosis at Sri Guru Ram Das Charitable Hospital in Amritsar, Punjab, India. The study spanned one year and seven months, from February 2020 to October 2021. A total of 100 female patients across all age groups with clinically suspected gynecological complaints related to the endometrium were included. Magnetic Resonance Imaging (MRI) was used to the examine the patients with endometrial lesions, and the results were compared with histopathology. The ADC values of benign and malignant lesions were statistically analysed using Student's t-test. Statistical significance was defined as a p-value < 0.05. Results: The mean age of participants with benign lesions was lower than that of those with malignant lesions (53.47±8.75 years and 60.00±13.93 years, respectively). The 100 individuals were divided into two groups: group I included individuals with benign lesions (58%), and group II comprised patients with malignant lesions (42%). Conventional MRI demonstrated a sensitivity of 86.2%, specificity of 91.8%, Positive Predictive Value (PPV) of 91.6%, and Negative Predictive Value (NPV) of 100% in lesion detection and differentiation. Combining DWI and ADC value mapping at a high b-value (b=800) in MRI significantly increased sensitivity (92.1%), specificity (97.9%), PPV (97.9%), and NPV (92.3%). Conclusion: The addition of DWI and ADC values to conventional MRI significantly improved the ability to distinguish malignant endometrial lesions from benign ones. However, histopathology remains the gold standard investigation as MRI inference cannot differentiate low-grade endometrial carcinoma from hyperplasia.