Ga-67 scintigraphy with a dual-head camera.

Abstract

High quality images are necessary for correct interpretation of Ga-67 studies in lymphoma. The authors were interested if there is a significant change in the quality of the Ga-67 images using a newly introduced dual-head camera compared with a conventional single-head camera. The tomographic spatial resolution, full width at half maximum, was found to be 9.63 mm compared with 13.7 for a single-head camera. The volume sensitivity was 380 cps/microCi/ml per axial cm as compared with 333 cps/microCi/ml, and point source sensitivity was 5.6 cps/microCi compared with 3.8. There was a significant difference (P < 0.001), when using the threshold technique, in the number of counts per pixel over a wide range of volumes and concentrations in phantoms when the two cameras were compared. There was also a significant difference (P < 0.001) in Ga-67 uptake in lymphoma lesions in patients when the same parameters were used for both cameras when using SPECT. The average uptake in lymphoma lesions, using a dual-head camera, was 529 counts/pixel with a range of 112 to 1275 counts/pixel in different tumors. With a single-head camera, the average for the same tumor was 216 counts/pixel with a range of 59 to 469 counts/pixel. The high sensitivity of the dual-head camera enabled high-quality, whole body scintigraphy, including the limbs, in 20 minutes compared with the 35 minutes necessary for the single-head camera for images which did not include the legs. Whole body Ga-67 scintigraphy is shown to be important in patients with lymphoma of the upper and lower limbs.(ABSTRACT TRUNCATED AT 250 WORDS)