Tima Davidson MD, Presenter: Nothing to Disclose

Elinor Goshen, Abstract Co-Author: Nothing to Disclose

Venous thromboembolism (VTE) is a well recognised and relatively frequent complication of malignancy, whereas tumor thrombosis (TT) is a rare complication of some cancers.This study was aimed to evaluate the contribution of F18-FDG PET/CT to the diagnosis of TT and its differentiation from VTE.  

PET/CT scans from 10 patients with suspected thrombotic lesions were retrospectively evaluated. Suspicion arose from positive PET in 7 cases, and or from findings on contrast enhanced CT in 3 patients. Criteria for positivity of PET are: increased focal or linear uptake of 18F-FDG in the involved vessel and standard uptake value (SUV) above 2.5. Findings were categorized as PETpositive (+) or PET negative (-) and compared to contrast enhanced CT or US Doppler, pathology when available and clinical follow-up. 

Seven cases of occult tumor thrombosis were identified by PET (+) scans and all 7 patients had CT findings consistent with thrombosis. Underlying pathologies included pancreatic , renal cell and head and neck squamous cell carcinoma, and 4 patients with  lymphoma. Three patients had thrombotic lesions on contrast enhanced CT and PET (-) scans. These were due to VTE (2cases) and leiomyomatosis. Accuracy of PET/CT to differentiate between TT and benign VTE was 100% in this small study.

Anatomic localization of positive PET lesions was enabled by the fusion of functional PET and anatomic CT data. Contrast enhanced CT reveals presence and defines extent of thrombotic lesions, yet the functional information from PET charcterizes the lesions. PET/CT may be contributory in the diagnosis of occult TT and its differentiation from VTE. 

Correct diagnosis of TT and its differentiation from VTE can alter patient management and prevent unnecessary long- term anticoagulation treatment.

Davidson, T, Goshen, E, 18-FDG Pet/CT in the Detection of Tumor Thrombosis.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6020069.html