Efficacy of FDG-PET Scan in Predicting the Histologic Grade of Follicular Lymphomas
Gang Zheng, Xiaofei Wang, Richard Wahl, Amy S Duffield, Kathleen H Burns, Christopher D Gocke, Michael J Borowitz, Milena Vuica-Ross. Johns Hopkins Hospital, Baltimore, MD
Background: 18F-fluro-deoxy-glucose positron emission tomography (FDG-PET) has become a routine measure for staging and follow up of patients with aggressive lymphomas. We investigated the efficacy of FDG-PET in predicting the histologic grade of follicular lymphomas.
Design: Patients diagnosed with follicular lymphoma between January 2007 and September 2012, who had received a corresponding FDG-PET scan for initial staging, were identified. FDG-PET scans were performed within two months of the original biopsy.
Results: 15 patients diagnosed with low grade (WHO grade 1 and 2) follicular lymphoma (FL1-2) who had a staging FDG-PET prior to therapy were identified, as well as 5 patients with a follicular lymphoma grade 3A (FL3A) and 7 patients with follicular lymphoma grade 3B (FL3B). FL1-2 showed a median SUV of 4.6 (2.2-14.7), FL3A showed a mean SUV of 5.5 (2.7-9.2) and FL3B showed a mean SUV of 13.7 (5.5-20.6). SUV values demonstrated significant correlation to WHO grades using a Wilcoxon signed-rank test. High SUV is an excellent predictor of follicular lymphoma grade 3B (vs FL1-2, p<0.001; vs FL3A, p<0.001). However, SUV values cannot differentiate between low grade follicular lymphomas and follicular lymphoma grade 3A (p=0.8). The correlation between SUV and Ki-67 proliferation index was compared using Parsons test (r=0.35, DF=26, p=0.02).
Conclusions: FDG-PET shows a significant correlation with pathologic grading of FL, but is not a reliable indicator of the Ki-67 proliferation index in these neoplasms. Thus, FDG-PET may provide a useful adjunct to objective grading of follicular lymphomas.
Tuesday, March 5, 2013 9:30 AM
Poster Session III # 160, Tuesday Morning