Does fluorodeoxyglucose-positron emission tomography-computed tomography help in correctly identifying grade of chondrosarcomas and thereby preventing the need for biopsy

(1) To evaluate potential of FDG PET-CT with regard to SUV in differentiating different grades of chondrosarcoma and to find whether SUVmax correlates with the postsurgery histopathology (2) To determine whether FDG PET-CT helps to avoid biopsy in cases of chondrosarcoma. The study was retrospectively carried out in 27 patients (17 males and 10 females) with suspicion of cartilaginous tumors, especially chondrosarcoma. All the 27 patients were investigated with either X-ray/CT scan/MRI. Pre-surgery biopsy was available in 20 patients. FDG PET-CT was performed in all patients prior to treatment. All patients underwent surgical management and histopathological diagnosis was confirmed in all cases. Results: SUVmax ranged from 0.9 to 2.8 in 7 tumors of Grade I, 1.7 to 12.7 in 17 tumors of Grade II, 5.8 to 38 in three tumors of dedifferentiated chondrosarcoma. An overlap in SUVmax was found in two patients. In comparison of grade of chondrosarcoma as per SUVmax and postsurgery histopathology, there was 100% concordance between the two methods in grade I and dedifferentiated tumors and 88.2% in grade II tumors. There was discordance between pre-surgery biopsy and post surgery histopathology in one tumor of grade I, 13 tumors of grade II and one tumor of dedifferentiated chondrosarcoma. Thus accuracy rate of pre-surgery biopsy was only 25%. The study demonstrates the utility of including ¹⁸F FDG PET-CT scan in diagnostic armamentarium of chondrosarcoma patients. Pre-treatment tumor SUVmax is a highly sensitive parameter for determining the grade of chondrosarcoma and thereby impacts the decision for optimal surgical management. (author)