SINGLE-PHOTON EMISSION COMPUTED-TOMOGRAPHY QUANTITATION OF GALLIUM CITRATE UPTAKE FOR THE DIFFERENTIATION OF LYMPHOMA FROM BENIGN HILAR UPTAKE

Purpose: To assess the role of quantitative gallium citrate (Ga 67) si ngle-photon emission computed tomography (SPECT) in differentiating ly mphoma from benign hilar uptake, concentrations of Ga 67 in 29 sites o f documented lymphoma and in 75 benign lesions were compared. Patients and Methods: One hundred seven thoracic Ga 67 SPECT studies obtained in 101 consecutive lymphoma patients were reviewed, Fifty-nine studies detected Ga 67 uptake in the hilar and or mediastinal regions. Forty- eight studies showed no such abnormality. The concentration of Ga 67 i n the thoracic lesions was measured using a quantitative SPECT techniq ue and its nature was determined by correlation with computed tomograp hic (CT) scans and follow-vp evaluation of the sites. Results: In 20 o f 59 abnormal studies (34%), there was lymphoma in the hilar and or me diastinal regions. In the remaining 39 abnormal studies (66%), Ga 67 u ptake was benign. There were 29 sites of lymphoma and 75 benign lesion s, The concentration of Ga 67 in lymphoma was significantly higher tha n in benign hilar uptake (13.2 +/- 5.4 %ID/mL x 10(-3) v 5.6 +/- 1.5 % injected dose (ID)/mL x 10(-3); P < .001). A concentration value of 8 .3 %ID/mL x 10(-3) was found to best separate lymphoma and benign upta ke, with a sensitivity of 90%, a specificity of 93%, a positive predic tive value of 84%, and a negative predictive value of 96%. Conclusion: Lymphoma and benign hilar uptake differ significantly in their concen tration of Ga 67. The present study shows that quantitative Ga-67 SPEC T reliably differentiates lymphoma and benign uptake. J Clin Oncol 13: 942-946. (C) 1995 by American Society of Clinical Oncology.