Duangkamon Prapruttam MD, Presenter: Nothing to Disclose

Sandeep Subhash Hedgire MD, Abstract Co-Author: Nothing to Disclose

Yun Mao MD, Abstract Co-Author: Nothing to Disclose

Mukesh Gobind Harisinghani MD, Abstract Co-Author: Nothing to Disclose

Debra Ann Gervais MD, Abstract Co-Author: Research Grant, Covidien AG

To assess the utility of apparent diffusion coefficient (ADC) in predicting and evaluating the response of the radiofrequency ablated renal cell carcinoma.

30 patients with 41 pathological confirmed renal cell carcinomas underwent MRI at 1.5T including diffusion weighted images before and after radiofrequency ablation. The ADC values of the tumor at b= 0, 100 and 600 s/mm2 were noted by drawing multiple regions of interest. Imaging features, histologic subtypes and Fuhrman grade of the tumor was also recorded. The participants were divided into 2 groups: complete treatment group (n=38) and residual disease group (n=3) based on follow up imaging and clinical notes. The variables were statistically analyzed.

Of 41 RCCs, 23.3% were papillary, 57% were clear cell and 3% chromophobe types. The mean pre-treatment tumor ADC value in the complete treatment group was 1.779 s/mm2 and pre-treatment ADC value of residual disease group was 1.609 s/mm2 (p=0.512). Given the substantial overlap, it was not possible to use the pre-ablation ADC value as a predictor of residual disease. Fuhrman grade showed significant correlation (p=0.005) with the post RF ablation response with 100% response rate in Fuhrman grade 1. For grade 2 this rate was 83.3% and for grade 3, it was 0%. There was no significant difference between ADC value of pre- and post radiofrequency ablated renal cell carcinoma. Though mean ADC values for the group before and after ablation did not differ, some cases showed increase in ADC and others showed decrease. The range in changes was -0.350 to 1.560.

ADC values in individual cases may increase or decrease after ablation limiting use of this marker in evaluating for viable tumor. Pre-ablation ADC did not predict outcome of ablation. Further studies are required to establish a cut of ADC value to distinguish complete responders from residual disease.

ADC values in renal tumors do not appear useful in predicting outcome or in assessing residual tumor after ablation.

Prapruttam, D, Hedgire, S, Mao, Y, Harisinghani, M, Gervais, D, Predictive Value of Apparent Diffusion Coefficient in Response Evaluation for the Radiofrequency Ablated Renal Cell Carcinoma: Preliminary Experience.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14019635.html