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%).

CONCLUSIONS

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.