The role of diffusion-weighted MR imaging in assessment of peritoneal lesions: radiologic-pathologic correlation

Background: Peritoneal diseases can be caused by a wide spectrum of pathologies including benign, primary, and secondary malignant lesions. Benign peritoneal diseases can mimic malignancies and have overlapping clinical, pathophysiological, and imaging appearances. Biopsy and histological assessment remain the gold standard for characterization of the peritoneal lesions; however, functional MRI techniques like diffusion imaging with quantitative assessment by ADC (apparent diffusion coefficient) measurements can help in the detection and characterization of different peritoneal lesions. The aim of this study was to evaluate the role of diffusion MR imaging in differentiating between benign and malignant peritoneal lesions with correlation to their pathological results. Results: Forty patients with peritoneal lesions were included in the study. According to histopathological results, 20 of them were of benign nature, and the other 20 were malignant. The mean ADC value of the benign lesions was 1.5 ± 0.5 × 10−3 mm2/s while that of malignant lesions was 0.9 ± 0.3 × 10−3 mm2/s with statistically significant difference (p < 0.00001), and a cutoff value of 1.15 × 10−3 mm2/s can be used to differentiate benign and malignant lesions with 85% sensitivity and specificity. In particular, we compared the mean ADC values of the eight cases of peritoneal tuberculosis with that of fourteen cases of peritoneal carcinomatosa, and it was also statistically significant (p < 0.001). However, we did not find a statistically significant difference between the mean ADC value of the benign and malignant cystic peritoneal lesions (p = 0.5). Conclusion: Diffusion MR imaging can provide a reliable non-invasive tool that can help in the differentiation between benign and malignant peritoneal lesions using qualitative and quantitative diffusion assessment through ADC measurements with a recommended cutoff value of 1.15 × 10−3 mm2/s.