title: Use of 18F-FDG PET/CT imaging for evaluation of patients with primary splenic lymphoma.
abstract: Primary splenic lymphoma (PSL) is a rare disease, and its management differs from other splenic malignancies. The purpose of the present study was to evaluate the role of 18F-FDG PET/CT in patients with PSL.
  
  
  METHODS
  We retrospectively evaluated the data of 17 patients with PSL (median age, 46 years; range, 3-64) who had undergone 50 18F-FDG PET/CT studies. Of the 50 PET/CTs, 15 were done for primary diagnosis/staging and 35 were done for restaging. PET/CT images were evaluated both qualitatively and quantitatively [maximum standardized uptake value (SUVmax)]. Combination of clinical/imaging follow-up and/or histopathologic diagnosis was taken as reference standard.
  
  
  RESULTS
  Of the total 50 F-FDG PET/CT studies, 27 studies (54%) were positive and 23 (46%) were negative for disease. PET/CT was true positive in 25 studies, true negative in 22 studies, false positive in 2 studies, and false negative in 1 study. Overall, per study-based sensitivity was 96.2%, specificity was 91.7%, and accuracy was 94%. In those studies performed for diagnosis/staging (15/50), PET/CT was true positive in all 15, with an accuracy of 100%. In those studies performed for restaging (35/50), sensitivity was 90.9%, specificity was 91.7%, and accuracy was 91.4%. No significant difference was seen in the accuracy of PET/CT between staging and restaging groups (P=0.601). On 18F-FDG PET/CT, splenic involvement was seen in 24 studies, lymph nodal involvement in 5 studies, liver involvement in 3 studies, and bone marrow involvement in 1 study. More than one site of disease was seen in 9 PET/CT studies. On semiquantitative analysis, the overall mean splenic lesion SUVmax was 6.9±7.9 (median, 4.6; range, 1.3-29). The mean value of ratio of SUVmax of splenic lesions and SUVliver was 4.4±5.5 (median, 2.4; range, 0.9-24.2). On comparison of areas under the curve, the mean value of ratio of SUVmax of splenic lesions and SUVliver was found to be superior to SUVmax alone for this differentiation of involvement from normal spleen (P=0.018).
  
  
  CONCLUSIONS
  18F-FDG PET/CT seems useful in patients with primary splenic lymphoma and shows high diagnostic accuracy.
authors.affiliation: From the Departments of *Nuclear Medicine, †Medical Oncology, Institute Rotary Cancer Hospital, and ‡Radiodiagnosis, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Sellam
authors.initials: S
authors.lastname: Karunanithi
authors.forename: Punit
authors.initials: P
authors.lastname: Sharma
authors.forename: Shambo Guha
authors.initials: SG
authors.lastname: Roy
authors.forename: Beth
authors.initials: B
authors.lastname: Vettiyil
authors.forename: Atul
authors.initials: A
authors.lastname: Sharma
authors.forename: Sanjay
authors.initials: S
authors.lastname: Thulkar
authors.forename: Chandrasekhar
authors.initials: C
authors.lastname: Bal
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008223:Lymphoma / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013160:Splenic Neoplasms / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18