Abstract
Patient A was a 72-year-old woman with history of high grade pleomorphic sarcoma of the left thigh and tumor thrombosis in the profunda femoris vein and superior femoral vein. At the time of the surgical resection, a Greenfield filter was placed in the inferior vena cava (IVC). At 6 months postoperatively, the patient had restaging positron emission tomography/computed tomography with F18-fluorodeoxyglucose (FDG PET/CT). While there was no evidence of residual or recurrent primary tumor, the images demonstrated an intraluminal lesion within the IVC just below the filter cap, with a standardized uptake value (SUV) of 12.0 (Panel A: arrows indicate an intensely FDG avid thrombus captured by the IVC filter). The patient underwent resection of the IVC and reconstruction. Surgical pathology confirmed the sarcoma thrombosis.
Panel A.
Patient B was a 51-year-old man with AIDS and nasal squamous cell carcinoma status post chemoradiation. The patient developed deep vein thrombosis (DVT) of bilateral lower extremities during chemotherapy, and had placement of the IVC filter afterwards. On restaging FDG PET/CT images, an FDG avid (SUV 5.0) thrombus of the IVC, trapped by the filter, was incidentally noted (Panel B: arrows show a small, moderately FDG avid thrombus trapped within the IVC filter). Six months after anticoagulation therapy, there was resolution of both lower extremity DVT on duplex ultrasound and IVC thrombus on repeated PET/CT.
Panel B.
Thrombosis is common in oncologic patients. It can be divided into two clinical entities: venous thromboembolism (VTE) and tumor thrombosis (TT). TT is a relatively rare complication of solid cancers and commonly develops from direct or contiguous spread from the primary tumor or metastasis into the blood vessels or at a distant site due to embolism. Differentiation of TT from benign VTE is of significant clinical impact to patient management. Anatomic imaging such as duplex ultrasound, CT, and magnetic resonance imaging (MRI) is used to detect the thrombosis, evaluate the extent and monitor the therapeutic response. However, these modalities have a limited ability in differentiating TT from VTE. Sporadic case reports have described the diagnostic role of tumor thrombosis by FDG PET/CT. FDG is a glucose analogue that accumulates in malignant tumors exhibiting increased glucose metabolism. However, FDG uptake is not specific and many benign or inflammatory diseases may demonstrate abnormal uptake. Increased FDG uptake has been reported in both aseptic and septic thrombosis.1,2 Although there is no established reliable SUV cut-off in differentiation, the FDG uptake of TT has been shown to be considerably higher than that of VTE.1,2 Here, patient A had surgical pathology confirmed IVC TT, and patient B was assumed to have VTE which was most likely septic considering his AIDS status. The uptake intensity of TT in patient A was significantly greater than that of VTE in patient B (SUV 12.0 vs SUV 5.0). The images highlight the diagnostic value of FDG PET/CT in the detection of TT.
The retrievable IVC filter is a commonly used vascular device intended to prevent life-threatening pulmonary emboli, but its effectiveness is not well established. 3 Although many data underscore the efficacy and need of the IVC filter, FDG PET/CT images of the presented cases have illustrated effective capture of the IVC thrombi by the filters.
