Kichang Han MD, Presenter: Nothing to Disclose

Seong Ho Park MD, Abstract Co-Author: Research Grant, DONGKOOK Pharmaceutical Co, Ltd Research Grant, General Electric Company

Hyoung Jung Kim MD, Abstract Co-Author: Nothing to Disclose

Seung Soo Lee MD, Abstract Co-Author: Nothing to Disclose

Ah Young Kim MD, Abstract Co-Author: Nothing to Disclose

Hyun Kwon Ha MD, Abstract Co-Author: Nothing to Disclose

No clear guidelines yet exist regarding how to use liver MRI in evaluating patients with newly-diagnosed colorectal cancer. This study was to investigate the clinical impact of liver MRI in staging evaluation of newly-diagnosed colorectal cancer patients, primarily focusing on those who demonstrate diminutive indeterminate hypoattenuating ("too-small-to-characterize" [TSTC]) focal hepatic lesions or metastasis-negative hepatic findings on standard staging CT.

We included 863 consecutive adults who had newly-diagnosed colorectal cancer without concomitant malignancies and received portal-phase contrast-enhanced abdominopelvic CT. Patients who had TSTC hepatic lesions without other suspicious/indeterminate hepatic findings (TSTC-liver-on-CT), metastasis-negative hepatic findings (negative-liver-on-CT), and hepatic lesions suspicious or indeterminate for metastasis excluding TSTC lesions as seen on CT were identified. Per-patient rate of hepatic metastasis unsuspected by CT for the entire cohort and the diagnostic yield of liver MRI for such lesions for those who had undergone liver MRI were assessed.

There were 261 TSTC-liver-on-CT patients, 464 negative-liver-on-CT patients, and 138 patients with suspicious hepatic findings on CT. Among TSTC-liver-on-CT patients, the rate of hepatic metastasis was 2.2% (5/230, excluding patients without follow-up) and the yield of liver MRI was 3% (3/96). Negative-liver-on-CT patients gave the MRI yield of 0% (0/94). Among negative-liver-on-CT patients, the rate of hepatic metastasis discovered within 6 months of curative surgery was 1.1% (4/350, excluding patients without follow-up) when the liver was cleared by negative CT alone and 2% (2/88, excluding patients without follow-up) when cleared also by negative MRI (P=0.347). Among the patients who had suspicious hepatic findings on CT, the MRI yield was 25% (19/77).

The diagnostic yield of liver MRI for hepatic metastasis was very low in newly-diagnosed colorectal cancer patients who showed TSTC hepatic lesions or metastasis-negative hepatic findings on CT. Staging liver MRI is likely unnecessary for them.

Staging liver MRI may not be effective or justified in patients with newly-diagnosed colorectal cancer who show TSTC hepatic lesions or metastasis-negative hepatic findings on CT, while it should be recommended for those who have hepatic findings suspicious of metastasis on CT.

Han, K, Park, S, Kim, H, Lee, S, Kim, A, Ha, H, Use of Liver MRI Following Standard Staging Abdomiopelvic CT to Evaluate Newly-diagnosed Colorectal Cancer Patients.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14004342.html