title: 18F-FDG PET-CT in the diagnosis of tumor thrombus: can it be differentiated from benign thrombus?
abstract: OBJECTIVE
  The correct diagnosis of tumor thrombosis and its differentiation from benign thrombus can change patient management and prevent unnecessary anticoagulation treatment. This study was aimed at evaluating the role of fluorodeoxyglucose (FDG) positron emission tomography-computed tomography (PET-CT) in the diagnosis of tumor thrombosis, and its differentiation from benign thromboembolism.
  
  
  METHODS
  We conducted a retrospective review of FDG PET-CT scans of patients who underwent the study for staging/restaging of a known malignancy and had FDG-avid thrombosis. Maximum standardized uptake value (SUV max) of the thrombus, SUV max of tumor (if any), and SUV max of mediastinal blood pool were calculated. PET-CT results were confirmed with clinical follow-up, structural imaging, and histopathology when available.
  
  
  RESULTS
  A total of 24 patients (15 male and nine female) with a mean age of 43.8 years (range: 3-72 years; median: 47.5 years) were evaluated. On the basis of structural imaging and clinical follow-up, 10 patients had benign and 14 patients had tumor thrombosis. On FDG PET-CT, uptake in the thrombus was linear in 18 patients and focal in six patients. The most common site of thrombosis was the inferior vena cava. The mean SUV max was 3.2 (range: 2.3-4.6; median: 3.3) in the benign thrombosis group and was 6.0 (range: 2.3-13.8; median: 3.3) in the tumor thrombosis group. The difference in SUV max was significant (P=0.013). On receiver operating characteristic analysis, a cut-off SUV max of 3.63 (sensitivity: 71.4% and specificity: 90%) was obtained to differentiate tumor thrombus from benign thromboembolism. In six patients, FDG PET-CT detected occult vascular thrombosis.
  
  
  CONCLUSIONS
  FDG PET-CT can detect active tumor thrombosis and is helpful in differentiating it from benign thrombus.
authors.affiliation: Department of Nuclear Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Punit
authors.initials: P
authors.lastname: Sharma
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Sunil
authors.initials: S
authors.lastname: Jeph
authors.forename: Sellam
authors.initials: S
authors.lastname: Karunanithi
authors.forename: Niraj
authors.initials: N
authors.lastname: Naswa
authors.forename: Arun
authors.initials: A
authors.lastname: Gupta
authors.forename: Arun
authors.initials: A
authors.lastname: Malhotra
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D019788:Fluorodeoxyglucose F18; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications*; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D054556:Venous Thromboembolism / Q000150:complications* / Q000175:diagnosis* / Q000000981:diagnostic imaging; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18