Diffusion-weighted and hepatobiliary phase gadoxetic acid-enhanced quantitative MR imaging for identification of complete pathologic response in colorectal liver metastases after preoperative chemotherapy.

PURPOSE

To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) and gadoxetic acid-enhanced magnetic resonance imaging (MRI) to differentiate colorectal liver metastasis (CRLM) with complete pathologic response from those with incomplete response in patients treated with preoperative chemotherapy.

METHODS

Gadoxetic acid-enhanced liver MRI and DWI were performed after completion of preoperative chemotherapy in patients with CRLM scheduled for liver resection. Metastases were classified as those with complete pathologic response (CR-CRLM) or incomplete response (IR-CRLM) according to postsurgical histopathology. Quantitative analysis was performed on non-contrast-enhanced images and hepatobiliary phase images following gadoxetic acid administration. Apparent diffusion coefficient values (ADC), normalized relative enhancement (NRE), and relative signal intensity difference (RSID) along with their diagnostic measures for detection of CR-CRLM were calculated for all lesions.

RESULTS

In 23 patients, 10 CR-CRLM and 35 IR-CRLM (mean diameter, 21.2 mm) were evaluated. In CR-CRLM, ADC was significantly higher after exclusion of the outliers (p = 0.030); and RSID was significantly lower (p = 0.008). Combined indices range of ADC = 1.25-1.9 × 10(-3) mm(2)/s, NRE = 0-35% and RSID <120 had 60% sensitivity and 100% specificity for detection of CR-CRLM.

CONCLUSION

DWI and gadoxetic acid-enhanced MRI appear promising for the detection of CRLM with complete response to preoperative chemotherapy. This could have significant implications for liver resection planning after preoperative chemotherapy.