Magnetic resonance imaging and positron emission tomography-computed tomography evaluation of soft tissue sarcoma with surgical and histopathological correlation.

PURPOSE: The aim of this study was to evaluate the role of positron emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) in characterization and pre-operative staging of soft-tissue sarcoma (STS) and correlating with operative and histopathological findings.

MATERIALS AND METHODS: Twenty patients (age range 16-72 years [mean 44.4 years]) with resectable and STS were included in this prospective study. Pre-operative MRI was carried out in all patients with acquisition of T1W, T2W, and short tau inversion recovery (STIR) sequences in appropriate planes. Contrast enhanced MRI was performed in four patients. Whole body PET-CT was performed in 13 patients. Demographic data, clinical features, pre-operative imaging analysis, operative, and histopathological findings were analyzed using SPSS software version 11.5.

RESULTS: The most common histologic type was malignant fibrous histiocytoma (MFH) (30%). Of 18 STSs 20 were high-grade. Agreement existed between MR and operative size. MRI had 100% negative predictive value (NPV) in predicting neurovascular bundle involvement. However, positive predictive value (PPV) was 33%. MRI had PPV of 20% while PET-CT had 50% PPV in detecting lymph node involvement. Overall staging accuracy of MRI was 75% when correlated with surgical and histopathological findings. Combined PET-CT and MRI staging, in 13 patients, was better (92.31%) when compared with staging with MRI (84.62%). Specific diagnosis on image characteristics was correctly suggested in 35% patients.

CONCLUSIONS: MRI is the robust modality in local staging of STSs and PET-CT adds greater accuracy to overall staging in combination with MRI.