Tumor microcirculation during a course of combined chemoradiation in patients with primary rectal carcinoma measured with dynamic T1 mapping

Abstract

A recently introduced dynamic T1 mapping technique was used to investigate changes of tumor microcirculatory parameters in 16 patients with clinically staged T3) primary rectal carcinoma during a course of preoperative combined chemoradiation. For dynamic T1 mapping an ultra-fast snapshot FLASH T1 mapping sequence was implemented on a 1.5T whole body MR scanner. Acquiring a series of T1 maps contrast media (CM) uptake and washout over an examination time of 40 min was monitored. From the obtained series of T1-maps perfusion-indices (PI) were calculated as the ratio of maximum slope of the tumor CM curve and the maximum of the arterial CM curve. Using pathologic classification of the resected tumors after therapy the patient group could be divided into patients with and without response to therapy. It was found that mean pre-therapy PI values of tumors showing therapy-response were significantly lower than for tumors without no therapy-response. In addition a different behavior of PI distributions within tumors for both groups was observed. The presented study indicates that PI values and their distributions within a tumor seem to be of predictive value for therapy outcome of preoperative therapy in patients with primary rectal carcinoma.