Evidence-based MR imaging follow-up strategy for desmoid-type fibromatosis

Summary

We retrospectively reviewed 296 MRI studies of 34 patients with histologically proven desmoid-type fibromatosis (DF). In each study, tumor volume and T2 signal relatively normal striated muscle were assessed. Volume variation and monthly growth rates were analyzed to determine lesion growth behavior (progressing vs stable/regressing lesions). Growth behavior was correlated with T2 signal, tumor location, beta-catenin status, treatment strategy, and follow-up duration. There were 25 women and 9 men with a mean age of 39.9?±?19 (4-73) years. Mean follow-up time in the patients included was 55?±?41 (12-148) months. In progressing lesions, the mean average monthly growth ratio was 10.9?±?9.2 (1.1-42.5) %. Interobserver variability of volume measurements was excellent (ICC?=?0.96). Mean interobserver measurement variation ratio was 20.4?±?23.6%. The only factor correlated with tumor growth behavior was T2 signal ratio (p <?0.0001). Seventeen out of 34 (50%) patients presented a signal change over the threshold of 1 during follow-up. There were five occurrences of secondary growth after a period of stability with a mean delay until growth of 38.2?±?44.2 (17-116) months. DF growth rate was quantitatively assessed. A threshold for volume variation detection was established. DF growth behavior was significantly related to T2 signal. An evidence-based follow-up strategy is proposed.