Can perfusion MRI predict response to preoperative treatment in rectal cancer?

Background and purpose: Dynamic contrast-enhanced MRI (DCE-MRI) provides information on perfusion and could identify good prognostic tumors. Aim of this study was to evaluate whether DCE-MRI using a novel blood pool contrast-agent can accurately predict the response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer. Materials and methods: Thirty patients underwent DCE-MRI before and 7-10 weeks after chemoradiotherapy. Regions of interest were drawn on DCE-MRI with T2W-images as reference. DCE-MRI-based kinetic parameters (initial slope, initial peak, late slope, and AUC at 60, 90, and 120 s) determined pre- and post-CRT and their Delta were compared between good (TRG1-2) and poor (TRG3-5) responders. Optimal thresholds were determined and sensitivities, specificities, positive predictive values (PPV), and negative predictive values (NPV) were calculated. Results: Pre-therapy, the late slope was able to discriminate between good and poor responders (-0.05 x 10(-3) vs. 0.62 x 10(-3), p < 0.001) with an AUC of 0.90, sensitivity 92%, specificity 82%, PPV 80%, and NPV 93%. Other pre-CRT parameters showed no significant differences, nor any post-CRT parameters or their Delta. Conclusions: The kinetic parameter 'late slope' derived from DCE-MRI could potentially be helpful to predict before the onset of neoadjuvant chemoradiotherapy which tumors are likely going to respond. This could allow for personalized treatment-options in rectal cancer patients. (C) 2014 Elsevier Ireland Ltd. All rights reserved.