title: Diagnostic value of CT, PET and combined PET/CT performed with low-dose unenhanced CT and full-dose enhanced CT in the initial staging of lymphoma.
abstract: OBJECTIVE
  The aim of this paper was to compare the accuracy of contrast-enhanced computed tomography (CT), positron emission tomography (PET), unenhanced low-dose PET/CT (LD-PET/CT) and full-dose enhanced PET/CT (FD-PET/CT) for the initial staging of lymphoma.
  
  
  METHODS
  One hundred and one lymphoma patients were examined by [18F]FDG-PET/CT including unenhanced low-dose CT and enhanced full-dose CT. Each modality of PET/CT was evaluated by a nuclear medicine physician and a radiologist unaware of the other modality, while the CT and PET images were interpreted separately by another independent radiologist and nuclear medicine physician respectively. The nodal and extranodal lesions detected by each technique were compared with a reference standard.
  
  
  RESULTS
  For nodal assessment, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (LR+), and negative LR (LR-) of LD-PET/CT were 97%, 96%, 98%, 95%, 26 and 0.02 respectively, and those of FD-PET/CT were 97%, 97%, 98%, 95%, 36 and 0.02. These results were significantly better than those of PET (sensitivity 82%, specificity 81%, PPV 88%, NPV 72%, LR+ 4.3, LR- 0.21). Likewise, both PET/CT displayed a higher sensitivity, NPV and LR- than CT (91%, 84%, 0.1 respectively). For organ evaluation, both modalities of PET/CT also had significantly better sensitivity and NPV than that of PET (LD-PET/CT: sensitivity 92%, NPV 90%; FD-PET/CT sensitivity 94%, NPV 92%; PET: sensitivity 70%, NPV 69%). The sensitivity, specificity, PPV and NPV for bone marrow involvement were 29%, 84%, 45% and 72% respectively for PET, and 29%, 90%, 56%, and 74% for both, LD-PET/CT, and FD-PET/CT. No significant differences were found between LD-PET/CT and FD-PET/CT, but FD-PET/CT detected important incidental findings in 5.9% of patients.
  
  
  CONCLUSIONS
  PET/CT is an accurate technique for the initial staging of lymphomas without significant differences between LD-PET/CT and FD-PET/CT. FD-PET/CT detects relevant incidental findings that are missed on LD-PET/CT.
authors.affiliation: Department of Radiology and Nuclear Medicine, Hospital Universitario La Paz Madrid, Spain. i.pinilla@telefonica.net
authors.forename: I
authors.initials: I
authors.lastname: Pinilla
authors.forename: N
authors.initials: N
authors.lastname: Gómez-León
authors.forename: L
authors.initials: L
authors.lastname: Del Campo-Del Val
authors.forename: D
authors.initials: D
authors.lastname: Hernandez-Maraver
authors.forename: B
authors.initials: B
authors.lastname: Rodríguez-Vigil
authors.forename: R
authors.initials: R
authors.lastname: Jover-Díaz
authors.forename: J
authors.initials: J
authors.lastname: Coya
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003974:Diatrizoate Meglumine; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008223:Lymphoma / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D019275:Radiopharmaceuticals; D012680:Sensitivity and Specificity; D014057:Tomography, X-Ray Computed; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D003974:Diatrizoate Meglumine