Comparison between early and delayed images of [67]Ga scintigraphy for evaluation of recurrent lymphoma

Despite widespread use of [67]Gallium 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 images. We aimed to compare 24 and 48 hours post injection planar gallium imaging for evaluation of lymphoma recurrence. 255 patients suspicious of recurrent lymphoma were included in the study. Twenty four and 48 hours post injection [10 mCi] whole body Gallium imaging was performed. Semi-quantitative evaluation [background corrected] was carried out in positive whole body [67]Gallium scans. Diagnosis of recurrence was made by combination of clinical or pathologic examination if possible. In 59 patients the final diagnosis was made by tissue biopsy. In case of uncertain diagnosis, follow up of the patients [mean duration of 13 months] was used. The diagnosis was finally made by the referring hematologist. Whole body gallium scintigraphy was positive in 115 out of 150 patients with recurrence [sensitivity of 76%]. Comparison of the 24 and 48 hour images did not show any new lesion in the 48 hour images. However, delayed 48 hours 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 lesion showed higher lesion to background ratio for 48 compared to the 24 hour images [p<0.001]. Considering higher lesion to background activity in the 48 hour images, delayed whole body [67]Gallium imaging may be more desirable for diagnosis of recurrent lymphoma, however 24 hour images may be sufficient. Delayed imaging can be reserved for suspicious activities [such as in abdominal images]. The strategy can save time and is more convenient for the imaging centers

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

Although PET scanning using F-18[FDG] is considered the superior radiotracer for tumor 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. 129 patients with suspicious recurrent lymphoma of the thorax were included into the study. All patients received 10mCi 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. 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. 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