Grading and characterization of soft tissue tumors on magnetic resonance imaging: the value of an expert second opinion report

OBJECTIVE To retrospectively compare the accuracy of the initial MRI (magnetic resonance imaging) report of referring radiologists and the second opinion report. MATERIAL AND METHODS MRI of 155 patients presenting with a soft tissue tumor (STT) in a single large community center were referred for inclusion in the Belgian Soft Tissue Neoplasm Registry (BSTNR). The initial report and the second opinion report were made independently. Histopathology (gold standard) was obtained in 90 patients (group 1). In 65 patients, the diagnosis was made by the combination of clinical findings and/or follow-up (group 2). In group 1, the concordance in grading and tissue-specific (TS) diagnosis between the referring center (RC) and expert center (EC) was reviewed. RESULTS In group 1, MR grading yields a sensitivity of 100% and a specificity of 89% in the EC. The sensitivity was 88% and the specificity 81% in the RC. The accuracy was significantly higher in the EC (92%) compared to the RC (83%) (p = 0.039). The TS diagnosis was correct in 50% versus 38.5% of malignant tumors and in 71.8% versus 51.6% of benign tumors in the EC and RC respectively. CONCLUSION A second opinion report increases the accuracy in the diagnosis of STT on MRI. MAIN MESSAGES • A second opinion MRI report increases the overall accuracy in the diagnosis of soft tissue tumors. • There is a good overall agreement in MR grading between the referring and expert institution. • In the expert center, there were fewer false-negative and false-positive diagnoses. • MRI performs better in the tissue-specific diagnosis of benign versus malignant STT.