Abstract
Aim
Grade is the most important predictor of the biological behaviour of soft tissue sarcomas. Assigning a pathologic grade is always a difficult task as discordance rate is 30-40% even among experienced sarcoma pathologists. Many of these tumours are heterogeneously large and only small fractions are sampled for biopsy. This emphasizes the need for an objective and accurate assessment of histology. Our aim is to evaluate the role of Choline as a tumour marker in (i) differentiating benign from malignant soft tissue tumour, (ii) to distinguish recurrent/residual tumours using in-vivo MR spectroscopy.
Methods
PMRS Study was performed at 1.5Tesla MRI machine of the lesions in 25 patients. Single-voxel (SVS) study has been done in 10 cases and chemical shift imaging (CSI) study characterised the heterogeneity of the tumour in 15 cases by using point – resolved spectroscopic sequence (PRESS) with echo time TR=2000/TE = 30, 135 & 270 msec. The choline peak, identified at 3.2 ppm in spectra was considered significant. MRS results and histopathologic findings were correlated and P < 0.001, considered being significant.
Results
Choline peak was found in 17 out of 17 patients with sarcomas where as three patient with benign and five treated sarcomas patients with no residual disease did not show any choline. In vivo spectroscopy here shows sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 100% each. In vivo spectroscopy shows sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 100% each where as preoperative biopsy shows 75%, 100%, 100%, 72.7% and 85% respectively.
Conclusion
Choline peak in PMRS study can predict the grade, margin status and tumour activity in recurrent and/or residual tumour. A major study should be done to validate its efficacy for routine use in oncology.
