Comparison between early and delayed images of 67Gallium Citrate scintigraphy for evaluation of recurrent lymphoma

Introduction: Despite widespread use of Gallium-67 (67Ga) for lymphoma evaluation, timing of imaging after injection is a matter of controversy and to the extent of our knowledge no direct comparison has been made between early and delayed gallium imaging in this regard. We aimed to compare 24 and 48h post injection planar gallium imaging in patients referred to our department for evaluation of lymphoma recurrence. Methods: 255 patients suspicious of recurrent lymphoma were included in the study. Twenty four and 48h post injection (370MBq) whole body 67Ga imaging was performed for the patients. Semi-quantitative evaluation (background corrected) was also performed in positive whole body 67Ga scans. Results: Results showed that the whole body gallium scintigraphy was positive in 115 out of 150 patients with recurrence (sensitivity of 76%). Comparison of the 24h and 48h image sets didn't show any new lesion on the 48h images. However, delayed 48h images were required for definite detection of the gallium avid lesions in the abdominal and pelvic areas in 40 patients. Semi-quantitative evaluation of the lesions showed higher lesion to background ratio for 24h compared to the 48h images (P<0.001). Conclusion: We conclude that 24h whole body 67Ga imaging is sufficient for the detection of lymphomas while 48h imaging can be reserved for suspicious lesions in the abdominal area.