Early results in the novel use of contrast-enhanced susceptibility-weighted imaging in the assessment of response and progression in desmoid fibromatosis: A pilot study in a specialized cancer institution

Routine radiologic reporting (RRR) often considers progressive desmoid tumors to have a higher proportion of T2-hyperintense and T1-shortened-enhancing components, while responsive or mature collagenized tumors demonstrate a higher proportion of T2-hypointense-non-enhancing components. We aim to determine the utility of the novel use of contrast-enhanced susceptibility-weighted imaging (CE-SWI) in Desmoid-Tumor treatment response assessment, distinguishing between the T1-shortening-enhancing/T2-hyperintense immature components from the T2-hypointense mature collagenized components. This pilot study included 10 single-lesion extremity desmoid fibromatosis patients undergoing standard-of-care magnetic resonance imaging, including CE-SWI. Three-dimensional (3D) tumor segmentation was performed using MIM software in 48 volumes of interest. Maximum diameter, volume, and modified Choi (mChoi) measurements were computed from CE-SWI and T2-weighted image (T2-WI). Five first-order radiomic features, including mean, skewness, kurtosis, and 10th and 90th percentiles, were calculated using in-house developed software (CARPI-AF). (i) RECIST Progression: We observed two cases of progression according to the T2-WI-based Response Evaluation Criteria in Solid Tumors standard (RECIST). Interestingly, CE-SWI-based-volume and CE-SWI-based-mChoi predicted the same assessment 4.5 months earlier than T2-WI-based-RECIST. RRR assessed both cases as progression; (ii) RECIST Stability: Out of the eight patients classified as having stable disease by T2-WI-based-RECIST, four discrepant progressions were determined: three patients showed an increase greater than 25% of T2-WI-based-volume, and two patients showed an increase greater than 25% of CE-SWI-based-volume. Moreover, from the RECIST stable group, four discrepant-positive responses were predicted by CE-SWI-based-mChoi (three patients) and T2-WI-based-mChoi (four patients). RRR only assessed one patient as having progressive disease; (iii) First-Order Radiomics: CE-SWI detected 23% more 90th-percentile voxels than T2-WI, while T2-WI demonstrated 8.5% more 10th-percentile voxels than CE-SWI. Notably, expected first-order response/progression-related changes in 10th-percentile, 90th-percentile, mean, and skewness were present in 90% of cases. In conclusion, CE-SWI-based-volume and CE-SWI-based-mChoi measurements could improve the prediction of response/progression in desmoid tumors, enhancing the ability in discriminating between T2*- hypointense-collagenized-mature and T1-shortened-enhancing immature components, respectively, in predominant mature responsive and immature progressive tumors, respectively. RRR is relatively insensitive to volumetric tumor changes before RECIST progression and tends to be better tuned with T2* signal and enhancement changes.