Maria Concetta Mumoli MD, Presenter: Nothing to Disclose

Davide Ippolito MD, Abstract Co-Author: Nothing to Disclose

Pietro Andrea Bonaffini MD, Abstract Co-Author: Nothing to Disclose

Orazio Minutolo MD, Abstract Co-Author: Nothing to Disclose

Cammillo Roberto Giovanni Leopoldo Talei Franzesi, Abstract Co-Author: Nothing to Disclose

Sandro Sironi MD, Abstract Co-Author: Nothing to Disclose

To assess the diagnostic value of quantitative apparent diffusion coefficient (ADC), as a predictor of tumor response to neoadjuvant chemo-radiation therapy (CRT) in patients with locally advanced rectal cancer (LARC), by analysing pre and post CRT values of ADC, correlated to tumor regression grade (TRG) obtained by histopathologic analysis.

A total of 70 patients with locally advanced rectal cancer (≥T3 or lymphnode positive) were evaluated before and after CRT treatment.Each patient scan consists of multiplanar T2 and T1 combined with diffusion-weighted sequences using a 1.5T MRI system(Achieva,Philips).For each patient dedicated workstation was used to evaluate the quantitative apparent diffusion coefficient (ADC) pre- and post-CRT MR images, by outlining freehand region of interest (ROIs) on the site of the lesion. Diagnostic accuracy of ADC values for predicting treatment response correlated with histopathological tumor regression grade (TRG) was evaluated, according to Mandard’s classification [responders (TRG1-2) and non-responders (TRG 3-5)].

Patients were assigned to the tumor responders group ( n = 48) or the tumor non-responders group ( n = 22) on the basis of histopathologic examination results following surgery. Before CRT, there wasn't significant difference in ADC value between responders vs non-responders: the mean tumor ADC values in the responders group was minimally lower than those in non-responders group (862.67 × 10−3 s/mm2 ± 206.66 vs 877.46 mm2 /sec ± 168.40). After CRT, the mean tumor ADC increased significantly in the responders group, 1444.46 × 10−3 mm2/sec ± 231.49 than in the nondownstaged group 1.267,47 × 10−3 s/mm2. The post-CRT ADC values were correlated to histopathologic tumor regression grade (TRG), and ROC analysis demonstrated the best cut-off value of 1,298 x 10-3 mm2 /sec, in determing responders patients yelding a sensitivity of 86% and specifity of 72%.

The quantitative assessment of post-CRT in ADC map, represents a non-invasive feasible tool,useful in the re-staging of patients with locally advanced rectal cancer (LARC), having good relationship with histology.

The post-CRT ADC values showed comparable relative accuracy as a predictor of tumor response to neoadjuvant chemo-radiation therapy (CRT) to tumor regression grade (TRG) obtained by histopathologic analysis.

Mumoli, M, Ippolito, D, Bonaffini, P, Minutolo, O, Talei Franzesi, C, Sironi, S, Diagnostic Efficacy of Diffusion-weighted MR Imaging in the Evaluation of Tumor Response to Neoadjuvant Chemoradiation Therapy, in Patients with Locally Advanced Rectal Cancer, Correlated with Tumor Regression Grade at Histology.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004916.html