Correlation of Ga-67 and CT scanning detection of metastatic melanoma

The authors evaluated 31 patients with suspected metastatic melanoma in whom axial CT and Ga-67 scans of the neck (6), chest (31), abdomen (32), and pelvis (3) were obtained within a 14-day period. Scans were interpreted both independently and then in combination, by observers blinded to the clinical findings. All patients had at least 12 months' clinical follow-up with subsequent x-ray studies, scans, or biopsies. Overall sensitivity for CT was 9% and the specificity was 72%, while Ga-67 imaging was 57% sensitive and 95% specific. Diagnostic accuracy was 68% for Ga-67 imaging and 89% for CT. The combined evaluation had a sensitivity of 81% and a specificity of 95%, with an accuracy of 86%. CT was more accurate for regions examined with both techniques, while Ga-67 imaging detected lesions in regions that were not scanned on CT. Somewhat surprisingly, the combined interpretation did not improve overall accuracy