Se Hee Jung MD, Presenter: Nothing to Disclose

Suk Hee Heo MD, Abstract Co-Author: Nothing to Disclose

Jin Woong Kim MD, Abstract Co-Author: Nothing to Disclose

Yong-Yeon Jeong MD, Abstract Co-Author: Nothing to Disclose

Sang Soo Shin MD, Abstract Co-Author: Nothing to Disclose

Heoung-Keun Kang MD, Abstract Co-Author: Nothing to Disclose

To investigate diffusion-weighted MR imaging (DWI) at 3.0-T MRI as an response indicator in locally advanced rectal cancer treated by preoperative combined chemoradiation.

Twenty-five consecutive patients with locally advanced rectal cancer who had underwent neoadjuvant chemoradiation were included. DWI was performed at 3.0-T MR scanner with three different b values 1 week prior to chemoradiation therapy and repeated after 4 weeks at the end of therapy. Quantitative ADC maps were calculated with images with b values of 0, 400, and 800 s/mm2. The mean ADC of rectal cancer before and after chemoradiation was compared according to response defined by Response Evaluation Criteria in Solid Tumors (RECIST) criteria.

Nineteen responding and six nonresponding rectal cancers were evaluated. Responding rectal cancer had a significantly lower pre-treatment mean ADC than nonresponding rectal cancer (Mann-Whitney U test, p=0.005). There was a linear regression relation (r=-0.638, p=0.006) between percentage size reduction of rectal cancer and pretreatment mean ADC. Responding rectal cancer had a significant increase of post-treatment mean ADC (Wilcoxon’s signed rank, p=0.008). In nonresponding rectal cancer, there was no significant change between pre- and post-treatment mean ADC (p=0.068). The differences between pre- and post-treatment mean ADC were correlated with percentage size reduction of rectal cancer (r=0.840, p<0.001).

Low pre-treatment mean ADC and increased post-treatment mean ADC of rectal cancer were predictive of good response to neoadjuvant chemoradiation therapy. Therefore, DWI at 3.0-T MRI could yield clinically important information for the prediction of neoadjuvant chemoradiation response in patients with locally advanced rectal cancer.

DWI at 3.0-T MRI can be used for response indicator in locally advanced rectal cancer treated by preoperative combined chemoradiation.

Jung, S, Heo, S, Kim, J, Jeong, Y, Shin, S, Kang, H, Diffusion-weighted MR Imaging in Rectal Cancer at 3.0-T MRI: Predicting Response to Neoadjuvant Chemoradiation Therapy.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8013960.html