The value of gallium 67 (Ga) imaging in monitoring lymphoma response to treatment was assessed in 25 patients with Ga-avid tumors and compared to body computed tomography (CT), chest radiographs, and palpation of tumor infiltrated peripheral lymph nodes. Ga imaging was negative in 95% (20/21) of the patients who were clinically considered to be in remission and in whom treatment was stopped. The disease did not recur during a follow-up of 12 to 26 months in 15 patients. Six patients developed recurrence of the disease 3 to 12 months after treatment was stopped. In all six patients Ga imaging became positive again at the time of the appearance of active disease. In the group of patients in remission, CT was negative in 57% (11/19), chest x-rays in 55% (6/11) and peripheral lymph nodes were palpated in none of the patients (13/13). In four patients that did not achieve remission after treatment, Ga scans were positive. Ga imaging appears useful in monitoring lymphoma response to treatment. This is probably because Ga imaging monitors tumor cell viability, whereas body CT and chest radiographs show the tumor mass, which may consist of fibrotic or necrotic tissue.

The results of planar and single photon emission computed tomography (SPECT) gallium-67 scintigraphy performed before and after treatment were compared in 77 patients with lymphoma at 240 sites. Before treatment, the sensitivity of planar scintigraphy was 78% and the specificity was 97%; after treatment, 84% and 96%, respectively. Before treatment, SPECT had a sensitivity of 85% and a specificity of 98%; after treatment, 92% and 99%, respectively. In addition, SPECT allowed better anatomical localization and showed the entire extent of lesions at 36 sites. SPECT was of special value after treatment in excluding disease at 16 sites with residual masses seen at computed tomography (CT). Long-term follow-up in these patients showed that their condition was in complete remission and that the CT appearance of a residual mass does not always mean residual cancer. Thus, Ga-67 SPECT is a suitable imaging technique for monitoring the response of lymphoma to treatment.

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Gallium 67 scintigraphic findings after one cycle of chemotherapy and at midtreatment are predictive of outcome in patients with aggressive non-Hodgkin lymphoma. CT findings are not predictive. Early 67Ga scintigraphy during chemotherapy is a good indicator of patients who may benefit from a change to a more aggressive treatment. A future study is necessary to investigate the potential effect of early change of treatment.