67Ga scan for evaluating response to therapy in malignant lymphoma

67Ga scintigrams in a patient with malignant lymphoma before and after chemotherapy are presented. 67Ga did not accumulate in the mostly necrotic mass with some viable cells. Negative uptake of 67Ga might reflect necrosis of the tumor; however, it is difficult to detect some residual tumor cells. Therefore, negative uptake of 67Ga in the mass seen in X-ray CT may not be totally reliable evidence of eradication of viable tumor cells.