Biomarkers of systemic treatment response: MR images of intratumoral fat deposition in colorectal liver metastases (CRLM) after chemotherapy.

Purpose: Colorectal cancer cells containing mobile lipids are said to be an early indicator of chemotherapy effects. The objective of the study was to examine the frequency and clinical relevance of intratumoral fat deposition in colorectal liver metastases (CRLM) post-chemotherapy using dual-echo chemical shift gradient-echo magnetic resonance imaging (MRI).

Methods: A retrospective analysis of 98 patients with CRLM diagnosed between 2017 and 2022 (69 M, mean age 62.87 ± 10.73 years old) who had an MRI after chemotherapy was performed. On dual-echo chemical shift gradient-echo MRI, intratumoral fat deposition of CRLM was evaluated. A signal intensity drop of ≥ 12% in opposed-phase images vs. in-phase images indicated intratumoral fat. After chemotherapy, the presence of fat deposition was correlated with patients' overall survival.

Results: Before and after chemotherapy, 0 (0%) and 29 (29.59%) patients exhibited intratumoral fat. The number of CRLM ranged from 1 to 25 with a median of 3 and a mean size of 32.58 ± 22.95 mm. The groups had statistically different survival times. Overall survival was shorter for patients with intratumoral fat deposition in CRLM (32 months (24-60, 95% CI)) than for patients without fat deposition in CRLM (48 months (36-NA, 95% CI)).

Conclusion: In our group, nearly 30% of CRLM patients exhibited intratumoral fat after chemotherapy. Patients with intratumoral fat deposition in CRLM have a shorter overall survival time. The presence of fat in CRLM correlates with a poor long-term prognosis.