Can Diffusion-Weighted MRI Predict Pathological Complete Response After Neoadjuvant Chemoradiation Therapy in Rectal Cancer Patients?

Giuseppe Petralia¹, Josep Garcia-Bennett², Luke Bonello³, Stefano Viotti³, Paul Summers¹, Maria Giulia Zampino¹, Maria Cristina Leonardi¹, Massimo Bellomi¹, ³

Better long-term outcome is reported for rectal cancer patients with pathological complete response (pCR) after neoadjuvant chemoradiation therapy (NACRT). Minimalist approaches are a reasonable alternative to radical surgery in such patients, with equivalent outcomes. T2-weighted MRI is not predictive of pCR. Diffusion-weighted MRI (DW-MRI) detects abnormalities in tissues and there is preliminary evidence that the apparent diffusion coefficient (ADC) may predict response to therapy. Fifty-nine patients underwent DW-MRI before and after NACRT, and ADC was calculated for tumour. ADC values before and after NACRT and their changes following treatment did not predict the pCR after NACRT in rectal cancer patients.