Davide Ippolito MD, Presenter: Nothing to Disclose

Francesca Invernizzi MD, Abstract Co-Author: Nothing to Disclose

Letizia Monguzzi MD, Abstract Co-Author: Nothing to Disclose

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

Gilda Rechichi MD, Abstract Co-Author: Nothing to Disclose

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

To assess the value of MR with diffusion imaging in patients who have undergone preoperative chemoradiotherapy for rectal cancer, being the tumor regression grade the standard of reference.

A total of 24 patients who had a biopsy-proven diagnosis of rectal carcinoma and who underwent neoadjuvant chemoradiation therapy were enrolled. All the patients underwent MR examination with a dedicated pelvic phased array multi-coil with acquisition of multiplanar T2 Turbo Spin Echo sequences. In addition DWI sequences (b factor:0 and 1000 mm²/sec) was also performed. The MR examination was performed prior to therapy (=MR 1) and two months later (=MR2),after the chemoradiation therapy.Two radiologists in consensus evaluated the changes of morphologic features related to the tumoral staging, and modification of apparent diffusion coefficient (ADC). Pathological TRG value was obtained according to the Mandard’s classification (TRG 1= complete regression; TRG=5 absence of regression).

All of the patients subsequently underwent total mesorectal excision and imaging findings were compared with pathological results. Fifthteen out of 24 patients showed complete (TRG 1) or subtotal regression (TRG 2) and were classified as responders, while the remaining patients (TRG 3 to 5) were considered non-responders. The mean ADC value in MR 1 examination was 0.86±0.22 x10-3 mm²/sec, whereas the mean values after the chemoradiation therapy was 1.43 ±0.25x10-3 mm²/sec. A significant correlation between ADC values and TRGs data was found (p<0.001). Also the increase of the mean ADC values pre and after treatment between the responders and not responders was found to be significantly different.

The MR study with DWI is a useful method for staging rectal cancer, and also has potential utility in the evaluation of CRT response.

The ADC values on DWI images may represent a complementary diagnostic tool , with good prognostic value in the assessment of neoadjuvant therapy response in patients with rectal cancer.

Ippolito, D, Invernizzi, F, Monguzzi, L, Bonaffini, P, Rechichi, G, Sironi, S, MRI with Diffusion-weighted Imaging and Apparent Diffusion Coefficient(ADC) Assessment in the Evaluation of Rectal Cancer Regression after Radio-Chemotherapy.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8007800.html