Faculty Bibliography

Twenty patients with known primary untreated and recurrent bone and soft tissue tumors underwent thallium imaging and three-phase bone imaging in the same session. The ratio of thallium uptake in the tumor tissue to the contralateral normal tissue areas was compared with the same ratio for phase 1 (blood flow or arterial phase), phase 2 (blood pool), and phase 3 (delayed medroxy-diphosphonate, MDP, uptake). There was poor correlation between Tl uptake and phases 1 and 3 of the bone scan ratios; r = 0.37 and 0.46; P = 0.097 and 0.047, respectively. The thallium uptake ratios correlated well with blood pool ratios (phase 2) (r = 0.84 and P less than 0.01). In contrast to uptake into normal muscle, Tl-201 uptake into tumor is not highly dependent on blood flow alone and other factors predominate in determining its magnitude.

In a retrospective study of a series of 30 adult patients during restaging of Hodgkin's disease after therapy, computed tomography (CT) and biopsy results were correlated with 67Ga SPECT in order to determine the value of SPECT imaging in monitoring recurrent mediastinal Hodgkin's disease. SPECT had an overall accuracy of 93% (28/30) and correctly identified active disease in 24 of 25, 96% of histopathologically proven recurrent Hodgkin's disease. Thus in this post-therapy setting, we have confirmed the high sensitivity of 67GA SPECT scans in patients selected for biopsy. Gallium-67 may prove particularly useful in detecting residual disease activity in patients in whom biopsy was positive but the interpretations of the CT scans were uncertain in regard to presence of tumors [8/30 (27%)]. In this group of patients, we found SPECT particularly helpful. A larger prospective series is under way to assess this possibility.