Impact of Dynamic Contrast Enhanced and Diffusion-Weighted MR Imaging on Detection of Early Local Recurrence of Soft Tissue Sarcoma.

BACKGROUND: Diagnosis of residual or recurrent tumor in soft-tissue sarcomas (STS) is a differential diagnostic challenge since post-therapeutic changes impede diagnosis. PURPOSE: To evaluate the diagnostic accuracy of quantitative dynamic contrast enhanced (DCE)-MRI and diffusion-weighted imaging (DWI) to detect local recurrence of STS of the limb. STUDY TYPE: Prospective. POPULATION: A totalof 64 consecutive patients with primary STS of the limbs were prospectively included 3-6 months after surgery between January 2016 and July 2021. FIELD STRENGTH/SEQUENCE: A 1.5 T; axial DWI echo-planar imaging sequences and DCE-MRI using a 3D T1-weighted spoiled gradient-echo sequence. ASSESSMENT: The quantitative DCE-MRI parameters relative plasma flow (rPF) and relative mean transit time (rMTT) were calculated and ADC mapping was used to quantify diffusion restriction. Regions of interest of tumor growth and postoperative changes were drawn in consensus by two experts for diffusion and perfusion analysis. An additional morphological assessment was done by three independent and blinded radiologists. STATISTICAL TEST: Unpaired t-test, ROC-analysis, and a logistic regression model were applied. Interobserver reliability was calculated using Fleiss kappa statistics. A P value of 0.05 was considered statistically significant. RESULTS: A total of 11 patients turned out to have local recurrence. rPF was significantly higher in cases of local recurrence when compared to cases without local recurrence (61.1-4.5) while rMTT was slightly and significantly lower in local recurrence. ROC-analysis showed an area under the curve (AUC) of 0.95 (SEM ± 0.05) for rPF while a three-factor multivariate logistic regression model showed a high diagnostic accuracy of rPF (R2  = 0.71). Compared with morphological assessment, rPF had a distinct higher specificity and true positive value in detection of LR. DATA CONCLUSION: DCE-MRI is a promising additional method to differentiate local recurrence from benign postoperative changes in STS of the limb. Especially specificity in detection of LR is increased compared to morphological assessment. EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 2.

Desmoid Tumors of the Foot: A Retrospective Study of Four Patients.

BACKGROUND: Desmoid-type fibromatosis (DF) is an aggressive (myo)fibroblastic neoplasm with an infiltrative growth pattern and a tendency for local recurrence. It is rarely seen at the foot. The aim of this retrospective study was to analyze clinical presentation, therapy, and outcomes in a consecutive series of four patients with DF at the foot. METHODS: From 1994 to 2014, four patients had been surgically treated. The resection margin was marginal or even intralesional in all. One patient already had local recurrence at first presentation. The end point was either local recurrence or progression of residual disease. RESULTS: The mean patient age was 27 years. In one patient, marginal excision healed the disease. In another patient, local recurrence after marginal resection necessitated distal phalanx amputation. Two other patients showed stable disease after either adjuvant radiotherapy or treatment with nonsteroidal anti-inflammatory drugs and tamoxifen. CONCLUSIONS: If surgery is necessary, operative margins are less important than keeping function for the patient. Radiotherapy might be an option to avoid major amputation. The role of adjuvant radiotherapy is controversially discussed. A watchful wait-and-see policy seems to be justified by the published data but may be difficult for DF at the foot.