18F-FDG PET/CT was used for evaluation of spleen infiltration in patients with B-cell non-Hodgkin lymphoma(NHL).Five patients with histological diagnosed B-cell NHL underwent1 8F-FDG PET/CT examination.On integrated PET/CT image,spleen infiltration was considered when PET images revealed a discrete margin of solid splenic masses or diffuse lesion of spleen with higher maximum standardized uptake value(SUV) greater than those of normal liver structures.CT images demonstrating a positive splenic index(>480 mL)or focal hypodensities were classified as positive for spleen infiltration.All the patients underwent systemic chemotherapy.The1 8F-FDG PET and CT results were compared with final diagnoses.All patients had spleen infiltration originating from B-cell NHL at final diagnosis.Final diagnoses,which were confirmed by clinical and CT(n=3) or1 8F-FDG PET/CT(n=1) follow-up in 4 patients and biopsy of 1 patient.On integrated PET/CT image,1 8F-FDG PET was true-positive in all 5 patients with spleen infiltration.CT was true-positive in 4 of the 5 patients with spleen infiltration and false-negative in 1 patients (spleen infiltration without morphology changes).The accuracies of1 8F-FDG PET and CT for evaluating the spleen infiltration were 100% and 80% at staging,respectively.Our preliminary results suggested metabolic imaging of1 8F-FDG PET/CT may be helpful in the diagnosis of spleen infiltration in B-cell NHL patients.These patients may benefit from1 8F-FDG PET/CT in diagnosis,when spleen infiltration without morphology changes,which may not be diagnosed exactly by conventional image. 18F-FDG PET / CT was used for evaluation of spleen infiltration in patients with B-cell non-Hodgkin lymphoma (NHL). Five patients with histological diagnostics B-cell NHL underwent 18F- FDG PET / CT examination. On integrated PET / CT image, spleen infiltration was considered when PET images revealed a discrete margin of solid splenic masses or diffuse lesion of spleen with higher maximum standardized uptake values ​​(SUV) greater than those of normal liver structures. CT images demonstrating a positive splenic index (> 480 mL ) or focal hypodensities were classified as positive for spleen infiltration. All the patients underwent systemic chemotherapy. 1 8F-FDG PET and CT results were compared with final diagnoses. All patients had spleen infiltration originating from B-cell NHL at final diagnosis. Final diagnoses , which were confirmed by clinical and CT (n = 3) or1 8F-FDG PET / CT (n = 1) follow-up in 4 patients and biopsy of 1 patient. On integrated PET / CT image, 1 8F-FDG PET was true-positive in all 5 patients with spleen infiltration.CT was true-positive in 4 of the 5 patients with spleen infiltration and false-negative in 1 patients (spleen infiltration without morphology changes). The accuracies of 1 8F-FDG PET and CT for evaluating the spleen infiltration were 100% and 80% at staging, respectively. Our preliminary results suggested metabolic imaging of 1 8F-FDG PET / CT may be helpful in the diagnosis of spleen infiltration in B-cell NHL. The patients may benefit from 18F-FDG PET / CT in diagnosis, when spleen infiltration without morphology changes, which may not be diagnosed exactly by conventional image.