Sensitivity of gallium scintigraphy for evaluation of recurrent lymphoma: Comparison of planar and SPECT imaging

  Introduction: Although PET scanning using F-18[FDG] is considered the superior radiotracer for tumnor imaging, Gallium-67 is still in use for some malignancies such as lymphoma and hepatoma. One of the strategies to improve the diagnostic accuracy of Gallium is to perform SPECT which is reported to be more sensitive compared to planar imaging. In this study we compared the sensitivity of SPECT and planar imaging in patients suspicious of thoracic recurrent lymphoma. Methods: 129 patients with suspicious recurrent lymphoma of the thorax were included into the study. All patients received 10 mCi Gallium-67-citrate intravenously. Twenty four and 48 hours post injection whole body and thoracic SPECT imaging was performed. The final diagnosis of recurrence was achieved by combination of clinical and imaging findings or pathologic examination whenever possible. Results: The final diagnosis of 83 (64.3%) patients was recurrence of lymphoma in the thoracic area and the remainder 46 (35.7%) were in remission. The sensitivity of planar and SPECT imaging for diagnosis of recurrent lymphoma was 63% ([52-73%] with 95% confidence intervals) and 87% ([79-94%] with 95% confidence intervals), respectively. Conclusion: In our study, 20 patients with the final diagnosis of lymphoma recurrence in the thoracic area had negative planar despite positive SPECT imaging. This showed an increase of 24% in sensitivity of the scan (from 63% to 87%) by adding SPECT imaging to the procedure. Our recommendation is integrating SPECT modality into all gallium scintigraphy for lymphoma recurrence.