Assessment of colorectal hepatic metastases by quantitative T2 relaxation time

Aim To determine the T 2 relaxation time of colorectal hepatic metastases and changes in T 2 relaxation times following chemotherapy. Materials and methods 42 patients with 96 hepatic colorectal metastases underwent baseline MRI. Axial T 1 , T 2 and multi-echo GRASE sequences were acquired. ROIs were drawn on T 2 relaxation maps, obtained from GRASE images, encompassing metastasis and normal liver to record T 2 relaxation time values. In 11 patients with 28 metastases, MRI was repeated using same protocol at 6 weeks following chemotherapy. The median pre-treatment T 2 values of metastases and normal liver were compared using the Mann–Whitney test. The pre- and post-treatment median T 2 values of metastases were compared using the Wilcoxon–Rank test for responding ( n =16) and non-responding ( n =12) lesions defined by RECIST criteria. The change in T 2 values (Δ T 2 ) were compared and correlated with percentage change in lesion size. Results There was no difference in the pre-treatment median T 2 of metastases between responding (67.3±8.6) and non-responding metastases (71.4±16.5). At the end of chemotherapy, there was a decrease in the median T 2 of responding lesions (61.6±12.6) p =0.83, and increase in non-responding lesions (76.2±18.4) p =0.03, but these were not significantly different from the pre-treatment values. There was no significant difference in Δ T 2 of responding and non-responding lesions ( p =0.18) and no correlation was seen between size change and Δ T 2 (coefficient=0.3). Conclusion T 2 relaxation time does not appear to predict response of colorectal liver metastasis to chemotherapy.