Objectives- To evaluate soft tissue lesions on 1.5T MR to determine the usefulness of MRS in differentiating benign and malignant lesions. Materials and methods- Contrast enhanced MRI and proton MR spectroscopy was performed on 20 patients on a 1.5T magnet system after initial evaluation of the lesion by radiography. MR examination was performed with a surface coil, either a flex body or extremity coil, appropriate for the location and size of the lesion. Multivoxel spectroscopy was performed at a TR/TE of 700/135. Area of interest was positioned within the lesion in the solid part excluding the necrotic region. Presence of choline peak was noted. The results of MR spectroscopy were compared with histology results obtained by either surgical biopsy in 4 cases, fine needle aspiration cytology in 11 cases, one case of leprosy was diagnosed by skin biopsy. No histological tests were done in a case of myositis ossificans, ruptured cysticercosis and two tubercular abscesess. The infective cases were followed up and showed improvement with antihelminthic/ antitubercular treatment respectively while the patient with myositis also was followed up. Results- On MRS choline was detected in 9/11 malignant lesions and 1/9 benign lesion. This benign lesion was a case of tubercular soft tissue abscess. MRS had a sensitivity of 81.8 % and a specificity of 88.9% in characterizing the lesions as benign and malignant on the basis of choline peak. Conclusion- Detection of choline in the tumour has high sensitivity and specificity for diagnosing malignancy and can be helpful in aiding the differential diagnosis of benign from malignant soft tissue masses on MRI.
