Bone lymphoma: 67Ga scintigraphy and CT for prediction of outcome after treatment

The purpose of the present study was to evaluate the role of 67Ga scintigraphy and CT in treatment monitoring of bone lymphoma.

Forty-four lymphoma patients with 91 sites of bone involvement were evaluated. Eight patients had Hodgkin's disease, and 36 patients had non-Hodgkin's lymphoma. Thirteen patients had primary lymphoma of the bone, and 31 patients had secondary lymphoma of the skeleton. 67Ga and CT studies were performed at baseline, during and at the end of treatment, and during follow-up. Positive 67Ga studies showed abnormal uptake in sites of lymphomatous involvement. Positive CT studies showed lesions with patterns of osteolysis, patterns of osteosclerosis, or a mixed pattern. A negative 67Ga or CT study showed disappearance of all lymphoma-related abnormalities. The sensitivity and specificity of 67Ga scintigraphy at presentation were calculated. Patterns of bone lymphoma on CT and their treatment-related changes were analyzed and recorded. Freedom-from-progression (FFP) curves were used to determine the prognostic value of positive and negative 67Ga and CT findings for predicting outcome after treatment.

The sensitivity of 67Ga for diagnosis of bone lymphoma was 93%, and the specificity was 91%. A CT pattern of osteolysis was seen in 70% of skeletal disease sites at diagnosis and in 21% during follow-up. Osteosclerosis was present in 23% of sites at diagnosis and in 38% during follow-up. 67Ga findings became negative in 25% of patients during treatment, whereas only 1 patient showed negative CT findings. Forty-two percent of patients had negative 67Ga findings at the end of treatment, compared with 18% who had negative CT findings. Sixty-one percent of patients had negative 67Ga findings during follow-up, compared with 21% who had negative CT findings. A statistically significant difference in FFP was found between patients with positive and negative 67Ga findings at all evaluated time points. No statistically significant difference in FFP was found at any time point between patients with positive and negative CT findings.

67Ga scintigraphy has a high sensitivity and specificity for diagnosis of bone lymphoma. Bone lymphoma may show osteosclerotic and osteolytic CT patterns at diagnosis, during treatment, and after treatment. In most patients, CT studies do not become negative even 1 y after treatment. 67Ga scintigraphy, however, may be used as a predictor of long-term outcome in patients with lymphoma of the skeleton.