Increased (18)F-fluorodeoxyglucose uptake in benign, nonphysiologic lesions found on whole-body positron emission tomography/computed tomography (PET/CT): accumulated data from four years of experience with PET/CT

PET and SPECT Imaging of Tumor Biology: New Approaches towards Oncology Drug Discovery and Development

Spiraling drug developmental costs and lengthy time-to-market introduction are two critical challenges facing the pharmaceutical industry. The clinical trials success rate for oncology drugs is reported to be 5% as compared to other therapeutic categories (11%) with most failures often encountered late in the clinical development process. PET and SPECT nuclear imaging technologies could play an important role in facilitating the drug development process improving the speed, efficiency and cost of drug development. This review will focus on recent studies of PET and SPECT radioligands in oncology and their application in the investigation of tumor biology. The use of clinically-validated radioligands as imaging-based biomarkers in oncology could significantly impact new cancer therapeutic development.

Highly metabolic thrombus of the portal vein: 18F fluorodeoxyglucose positron emission tomography/computer tomography demonstration and clinical significance in hepatocellular carcinoma

AIM: To assess the ability of ¹⁸F-fluorodeoxyglucose positron emission tomography/computer tomography (¹⁸F-FDG PET/CT) to differentiate between benign and malignant portal vein thrombosis in hepatocellular carcinoma (HCC) patients.

METHODS: Five consecutive patients who had HBV cirrhosis, biopsy-proven HCC, and thrombosis of the main portal vein and/or left/right portal vein on ultrasound (US), computer tomography (CT) or magnetic resonance imaging (MRI) were studied with ¹⁸F-FDG PET/CT. The presence or absence of a highly metabolic thrombus on ¹⁸F-FDG PET/CT was considered diagnostic for malignant or benign portal vein thrombosis, respectively. All patients were followed-up monthly with US, CT or MRI. Shrinkage of the thrombus or recanalization of the vessels on US, CT or MRI during follow-up was considered to be definitive evidence of the benign nature of the thrombosis, whereas enlargement of the thrombus, disruption of the vessel wall, and parenchymal infiltration over follow-up were considered to be consistent with malignancy. ¹⁸F-FDG PET/CT, and US, CT or MRI results were compared.

RESULTS: Follow-up (1 to 10 mo) showed signs of malignant thrombosis in 4 of the 5 patients. US, CT or MRI produced a true-positive result for malignancy in 4 of the patients, and a false-positive result in 1. ¹⁸F-FDG PET/CT showed a highly metabolic thrombus in 4 of the 5 patients. ¹⁸F-FDG PET/CT achieved a true-positive result in all 4 of these patients, and a true-negative result in the other patient. No false-positive result was observed using ¹⁸F-FDG PET/CT.

CONCLUSION: ¹⁸F-FDG PET/CT may be helpful in discriminating between benign and malignant portal vein thrombi. Patients may benefit from ¹⁸F-FDG PET/CT when portal vein thrombi can not be diagnosed exactly by US, CT or MRI.