VALUE OF MR FINDINGS IN PREDICTING THE NATURE OF THE SOFT-TISSUE LESIONS - BENIGN, MALIGNANT OR UNDETERMINED LESION

Objective: To evaluate the value of each MRI findings in differentiati ng the nature of soft tissue lesions. Subjects and Methods: We perform ed a blind retrospective review of MR imaging in 65 consecutive soft-t issue lesions (cystic lesions in or around the joints, and the soft ti ssue abnormalities directly related to a known trauma were excluded). Morphology and signal intensity characteristics were analyzed. Each le sion was considered as benign tumor malignant tumor, benign but locall y aggressive lesion, and undetermined. The final diagnosis was establi shed pathologically (n=45), and by the association of other imaging st udies, clinical findings and follow-up over 2 yr (n=20). Results: Invo lvement of one compartment was equal in malignant (57.1%) and benign ( 56.2%) tumors, whereas multicompartmental involvement was most common in non-tumoral lesions (39.1%) (P<0.05). Well-defined margins were mos t frequent in benign tumors (189.2%) (P<0.05). The change from homogen eous to heterogeneous pattern on T1- and T2-weighted sequences as a pr edictor of malignancy showed a sensitivity of 77.7% and a specificity of 20%, Based on the MRI findings a diagnosis of benign lesion was est ablished with a sensitivity of 60.7% and a specificity of 77.7%; malig nant tumor with a sensitivity of 78.5% and a specificity of 96% and be nign locally aggressive lesions with 54.5% and 88.1%, respectively. Wi th the addition of the clinical data, an etiologic diagnosis was perfo rmed in 78.5% benign tumors, in 85.7% malignant tumors, and in 95.6% b enign non-tumoral lesions. Undetermined lesion was diagnosed in eight masses. Conclusion: Soft tissue lesions can be diagnosed with certaint y in many benign tumors based on the integrated evaluation of morpholo gy and signal intensity MR findings. The association of MR and clinica l data allowed us to identify benign but locally aggressive lesions, m ostly related to infection. MR findings are highly specific for malign ant tumor, although a histologic diagnosis cannot be performed based o nly on image analysis. When a mass is undetermined and no criteria for benignity or malignancy can be established, pathologic analysis shoul d be always performed. Copyright (C) 1996 Elsevier Science Ltd.