Quantification of fat content in lipid-rich myxoid liposarcomas with MRI: a single-center experience with survival analysis

Abstract

Objective

To determine the fat content of myxoid liposarcomas (MLS) on MRI and to identify any association between lipid content and survival.

Materials and methods

The fat percentage of MLS diagnosed between January 2006 and December 2016 at a single institution was assessed by two radiologists on preoperative MR images. A Cox proportional hazard model was used to determine any association between tumor fat percentage and survival time. Tumor fat percentage was the single predictor in the model. A significance level of 0.05 was used. The Kaplan–Meier estimator was also used to provide a nonparametric estimate of the survivor function within the entire sample and within two patient subgroups consists of lipid-rich and lipid-poor tumors. Lipid-rich tumors were defined as any tumors showing more than 20% of fat on MRI. A 20% cutoff was determined arbitrarily.

Results

Of the 43 cases identified through retrospective review, 8 tumors demonstrated ≥10% fat on MRI, and 4 tumors demonstrated ≥20% fat (highest fat percentage, 38%). There was no significant survival difference between patients with high tumor fat, which was defined as ≥20% fat, compared with those with little to no tumor fat.

Conclusion

Myxoid liposarcomas may demonstrate a higher fat content on MRI than has previously been reported in the literature. Increased tumor fat percentage in lipid-rich tumors was not found to be associated with increased risk of death. Radiologists must be aware of the existence of MLS lesions with higher fat content.

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