Abnormal vascularization of soft-tissue sarcomas on conventional MRI: Diagnostic and prognostic values

PURPOSE: To assess the prevalence of abnormal vessels inside and surrounding soft-tissue sarcomas (STS) on conventional MRIs so as to evaluate their correlations with particular histotypes, histological grades, and prognosis. METHOD: This single-center retrospective study included 157 adult patients (median age: 61) with histologically-proven non-metastatic STS. All had pre-treatment conventional contrast-enhanced MRI. Two radiologists reported: presence of abnormal flow-voids, number and distribution (peri-tumoral and/or intra-tumoral), percentage of tumor circumference it covered, maximal diameter. The radiological findings were correlated with histopathology. Associations were evaluated with Chi-2 or t-tests. Survival analysis (for metastasis-free survival (MFS) and overall survival (OS)) included log-rank tests and multivariate Cox-model. RESULTS: Twenty-nine of 157 (18.5%) STS showed abnormal flow-voids that were peri-tumoral (9/157, 5.7%), intra-tumoral (5/157, 3.2%) or both intra- and peri-tumoral (15/157, 9.6%). Ten STS had more than 5 flow-voids, all being grade II-III, namely: 4 undifferentiated sarcomas, 2 solitary fibrous tumors, 1 alveolar soft-part sarcoma (ASPS), 2 leiomyosarcomas and 1 pleomorphic liposarcoma. The distribution of flow-voids was associated with survivals in the univariate analysis: patients with abnormal peritumoral flow-voids (APTFV) showed poorer OS and MFS (p = 0.039 and 0.014, respectively). These associations did not remain significant in multivariate analysis. Radio-pathological correlations revealed large tortuous tumoral neo-vessels with intra-vascular thrombi of tumor cells in ASPS and in one case of undifferentiated sarcoma displaying enrichment in genes involved in neo-angiogenesis at transcriptional level. CONCLUSIONS: APTFV on conventional MRIs may be associated with a higher risk of metastatic relapse and poorer OS in STS patients.