OBJECTIVETo investigate the diagnostic value of (18)F-FDG PET-CT imaging in primary extranodal lymphoma.

METHODSA retrospective analysis of 139 clinically suspected primary extranodal lymphoma patients examined by PET-CT and confirmed by biopsies was performed. Considering the pathological diagnosis as the gold standard, PET-CT imaging of all patients was compared with CT and PET to evaluate the efficacy of 18F-FDG PET-CT in detection of primary extranodal lymphoma. The maximal standardized uptake value (SUVmax) from primary extranodal lymphoma patients was compared, and the data were analyzed by χ² test.

RESULTSOf the total 139 analyzed cases, 128 patients were confirmed to have primary extranodal lymphoma. The sensitivity, specificity and positive rate of PET-CT were 82.8%, 81.8% and 82.7%, respectively, that of CT were 65.6%, 72.7% and 66.2%, and that of PET were 78.9%, 36.4% and 82.0%, respectively. The sensitivity and accuracy of PET-CT were better than that of CT (χ²=9.881, 10.006; P=0.003, 0.002). The specificity of PET-CT were better than that of PET (χ²=4.487, P=0.034). In the gastrointestinal lymphoma, the sensitivity of PET-CT were better than that of CT (χ²=5.110, P=0.024). In the head and neck lymphoma, the sensitivity of PET-CT were better than that of CT (χ²=5.278, P=0.022). In the diffuse large B-cell lymphoma, the sensitivity of PET-CT were better than that of CT (χ²=8.711, P=0.003). The SUV max of mucosa-associated lymphoma was significantly different from that of diffuse large B-cell lymphoma and natural killer/T-cell lymphoma (7.4±4.6 vs 15.8±10.6, P=0.032; 7.4±4.6 vs 13.6±7.1, P=0.046), respectively.

CONCLUSION18F-FDG PET-CT imaging is important in the diagnosis of primary extranodal lymphoma, but the differential diagnosis with other disease is important, and the result should be combined with multiple biopsies.