FDG Uptake in Inferior Vena Cava Tumor Thrombus From Renal Cell Carcinoma on Positron Emission Tomography

The role of 18F-FDG PET/CT in differentiating malignant from benign portal vein thrombosis

AIMS

In this retrospective study, we evaluated the role of (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in differentiating malignant from benign portal vein thrombosis (PVT) in patients with known malignant tumors.

METHODS

Seventy-two patients with histologically or clinically confirmed PVT and who had undergone (18)F-FDG PET/CT were included. Visual and semiquantitative analyses of PET/CT scans were performed. Metabolic activity was measured using the maximum standardized uptake value (SUVmax) by drawing the region of interest at the site of thrombosis. Receiver operating characteristic analysis was conducted to identify the optimal cutoff of SUVmax for detecting neoplastic thrombosis. Malignancy was defined using the following criteria: (1) visual analysis and (2) SUVmax >3.35. PET/CT results were confirmed with histopathological results and clinical and imaging follow-up.

RESULTS

The SUVmax of tumor thrombus (6.37 ± 2.67) was significantly higher than that of bland thrombus (2.87 ± 1.47; P < 0.01). The sensitivities, specificities, and accuracies for the two criteria were 91.5 % and 93.6; 64.0 and 80.0 %; and 81.9 % and 88.9 %, respectively.

CONCLUSION

(18)F-FDG PET/CT is a promising new method for distinguishing between portal venous neoplastic thrombosis and bland thrombosis using semiquantitative analysis, with the optimal cutoff value of SUVmax >3.35 as a criterion.

Migrating tumor thrombus trapped within the greenfield filter of the inferior vena cava and depicted by FDG PET/CT

A 72-year-old woman with leiomyosarcoma of the left thigh underwent a whole-body FDG PET/CT for staging, which demonstrated a large FDG-avid tumor in the left thigh and tumor thrombosis involving the profunda femoris artery/vein and superior femoral vein. A Greenfield filter was placed in the inferior vena cava before the radical resection of the tumor and thrombosis. Postoperative PET/CT showed an FDG-avid embolus trapped within the solid apical cap of the filter in the inferior vena cava. It was unknown if the tumor embolus migrated to the inferior vena cava before or during the surgical procedure of radical resection.

Can Initial (18)F-FDG PET-CT Imaging Give Information on Metastasis in Patients with Primary Renal Cell Carcinoma?

Purpose

The aim of this study was to investigate the relationship between the maximum standardized uptake values (SUVmax) of primary renal cancers with and without metastatic lesions, if any. We also studied the relationship between the size of primary renal cancers and their SUVmax, and tried to find a clinical value of ¹⁸F-FDG PET-CT for the initial evaluation of renal cell carcinoma (RCC).

Methods

The cases of 23 patients, 16 men and 7 women, who underwent PET-CT examination before operation were retrospectively reviewed. We measured the SUVmax of the primary renal cancers and those of any existing metastatic lesions, and the size of the primary renal cancers. We compared the SUVmax of primary RCCs with metastases and those without metastases, SUVmax of primary RCC and those of metastases, and studied the correlation between the size and SUVmax of primary RCCs.

Results

The SUVmax of primary RCC of the 16 patients without metastasis ranged from 1.1 to 5.6 with a median value of 2.6. Those of the patients with metastasis ranged from 2.9 to 7.6 with a median of 5.0. The size of the all 23 primary renal cancers ranged from 1.7 cm to 13.5 cm, with a median of 4.5 cm, and their SUVmax ranged from 1.1 to 7.6, with a median of 2.9. There was a statistically significant difference between the SUVmax of the primary RCC with metastasis (5.3 ± 1.7) and those without metastasis (2.9 ± 1.0). There was a moderate positive correlation between the sizes and SUVmax of all 23 primary RCCs. However, there was no statistically significant correlation between the sizes and SUVmax of primary RCCs with metastatic lesions and the same for RCCs without metastasis. The cutoff value of SUVmax for predicting extra-renal lesion was 4.4 and that for size was 5.8 cm according to the receiver operating characteristic curves.

Conclusions

Those who have primary RCC with high SUVmax are suggested to have a likelihood of metastasis. Also, there was a moderate trend of increasing value of SUVmax of primary RCC as their size increases. Physicians should beware of missing extra-renal lesions elsewhere.

Extensive tumor thrombus in a case of carcinoma lung detected by F18-FDG-PET/CT

Tumor thrombus is a rare complication of solid cancers, mainly seen in cases of renal cell carcinoma, wilm's tumor, testicular carcinoma, adrenal cortical carcinoma and hepatocellular carcinoma.[1] Tumor thrombus in inferior vena cava is a rare complication of primary carcinoma lung. It should be identified so as to rule out venous thromboembolism and avoiding unnecessary anticoagulant therapy. We describe a case where F18-Fluorodeoxyglucose (FDG) positron emission tomography - computed tomography (PET/CT) helped to identify extensive tumor thrombus.

Imaging of renal cell carcinoma: state of the art and recent advances

BACKGROUND AND AIM

Renal cell carcinoma (RCC) is the 13th most common cancer worldwide and accounts for 4% of all adult malignancies. Herein the state of the art and recent advances in cross-sectional radiological imaging applied to RCC are reviewed, including ultrasonography, computed tomography, magnetic resonance imaging, and positron emission tomography.

METHODS

Literature search of peer-reviewed papers published by October 2010.

RESULTS

In front of more conventional and widespread imaging tools, such as ultrasonography and computed tomography, an array of newer and attractive radiological modalities are under investigation and show promise to improve our ability to noninvasively detect renal tumors and its recurrences, accurately assess the extent of the disease, and reliably evaluate treatment response, particularly in the era of antiangiogenetic therapy.

CONCLUSIONS

Recent major advances in radiological imaging techniques have considerably improved our ability to diagnose, stage and follow-up RCC. Further studies are needed to evaluate the potential of most recent and still investigational imaging tools.