New MRI Advances in Post-Operative Assessment of Pelvic Tumors

Abstract Background: Differentiating residual or recurrent tumor from treatment related tissue changes after surgical resection of malignancy is often challenging due to non-specific signal findings by standard MRI with histologic examination remain-ing the standard reference yet it can't be done in all cases. The addition of contrast-enhanced MRI has proven to be beneficial in addition DWI detects the biologic characteristics of tissue and gives unique data regarding the cellularity and the status of molecular content of water. Aim of Study: In this study we aimed to assess the role of Diffusion-Weighted Imaging (DWI) and contrast-enhanced MR imaging in combination with standard MRI in the evalu-ation of recurrent intrapelvic malignancy. Patients and Methods: Prospective study of 108 post-operative patients that require follow-up MRI imaging after resection of intra-pelvic malignancies in isolation or with radiation and/or chemotherapy with mean age of 55 years. Two radiologists prospectively assessed the morphological and qualitative descriptors of the included lesions (restricted diffusion) and quantitative analysis of the ADC maps. The mean ADC value of the lesions was calculated and correlated with the histopathology which was established by means of an open or a core needle biopsy (considered as the standard reference). Results: There was significant difference between the mean ADC value of recurrent/residual lesions and of benign post-operative changes (p 0.0001) with high sensitivity of mean ADC (93.1%) and specificity (85.7%) (p value 0.000095). Conclusion: DWI is a contrast-free modality that allows for both morphological and quantitative analysis. ADC value may not be the proper modality to determine the prognosis of intra pelvic cancer due to overlap values, yet it could aid discrimination of recurrent/residual tumor from post-operative changes as well as being a good predictor of cancer cells that would respond to chemotherapy.