Comparison of gallium scan, computed tomography, and magnetic resonance in patients with mediastinal Hodgkin's disease

Background: In patients with Hodgkin's disease, the use of gallium-67 scintigraphy (Ga-67) compared to conventional staging and restaging techniques is still controversial. In particular in a combined modality treatment with chemotherapy and radiotherapy given in sequence, its role in detecting active disease after chemotherapy may be useful in planning the subsequent radiotherapeutic strategy. Patients and methods: From March 1990 to September 1994, 125 patients with previously untreated histologically proven Hodgkin's disease were enrolled in two different prospective trials according to clinical stage. Staging procedures included Ga-67, chest- abdominal computed tomography (CT), and/or magnetic resonance (MR). All three tests were performed in 53 patients at staging and in 47 at restaging. Results of Ga-67 at staging were compared to conventional procedures or pathological findings. Results of Ga-67, CT scan, and MR at restaging were compared to disease outcome during the follow-up. Finally a cost/benefit ratio for each test was determined. Results: At staging, Ga-67 showed lower sensitivity than CT and MR (90 vs. 96 and 100%, respectively) because of the number of false-negative images. Nevertheless, by using both CT and Ga-67 scan, the sensitivity is equal to that observed with MR (100%). At restaging, Ga-67 is superior to CT scan and equivalent to MR in detecting true negative patients (specificity: 98% vs. 45% vs. 92%). Conclusion: As a single technique, Ga-67 scan cannot substitute for CT scan or MR in staging patients with Hodgkin's disease. Nevertheless, Ga-67 scan has an important role in defining complete remission after treatment and therefore in planning subsequent treatment. Considering the lower costs of CT scan plus Ga-67 ($320) versus MR alone ($810), the two tests may be considered procedures of choice in staging as well as in restaging patients with Hodgkin's disease.