Comparison of abbreviated and complete MRI protocols for treatment response assessment of colorectal liver metastases.

OBJECTIVE

To compare abbreviated magnetic resonance imaging (MRI) to complete MRI for treatment response assessment of colorectal liver metastases.

MATERIAL AND METHODS

This retrospective study included consecutive patients with colorectal liver metastases between January 1, 2012, and December 3, 2021, who were undergoing chemotherapy and who had at least one follow-up gadoxetic-enhanced MRI. For each patient, two MRIs (baseline MRI and follow-up MRI) were randomly selected. Follow-up MRIs were separated into two sets of images: complete MRIs, including all imaging sequences, and abbreviated MRIs, including coronal and axial hepatobiliary phase imaging, axial diffusion-weighted imaging, and coronal T2-weighted imaging. Seven radiologists reviewed the two sets of images, with a month's break in between, assessing Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 category and the presence of new lesions, with each reader assigned 80-91 patients. Inter-reader agreement was assessed using Fleiss' kappa (κ).

RESULTS

One-hundred ninety-five patients (mean age 54.4 +/- 12.1 years, 135 men) were evaluated. Intra-reader agreement between abbreviated and complete MRI was substantial for the RECIST 1.1 category (κ, 0.66-0.89) and the detection of new lesions (κ, 0.63-0.81). Inter-reader agreement was substantial for RECIST 1.1 category using abbreviated MRI and complete MRI (κ, 0.71 (95% CI: 0.65-0.78) and 0.68 (95% CI: 0.61-0.75)), and moderate for the presence of new lesions using abbreviated MRI and complete MRI (κ, 0.56 (95% CI: 0.41-0.69) and 0.49 (95% CI: 0.35-0.65)).

CONCLUSION

Abbreviated MRI may serve as an alternative to complete MRI for the follow-up of patients with colorectal liver metastases.

KEY POINTS

Question Abbreviated MRI is a time-saving and cost-effective exam, but only one study has compared it with complete MRI for treatment response assessment of colorectal liver metastases. Findings In our study, abbreviated follow-up MRI achieved substantial inter-reader agreement for the RECIST 1.1 category and moderate inter-reader agreement for the presence of new lesions. Clinical relevance Abbreviated liver MRIs are adequate substitutes for complete liver MRIs for colorectal liver metastases in the follow-up setting when the goal is to assess treatment response, resulting in shorter examination times and potential reductions in costs.