Benjamin S. Halpern

Performance of 2-Deoxy-2-[F-18]fluoro-d-glucose Positron Emission Tomography and Integrated PET/CT in Restaged Breast Cancer Patients

PurposeThis study was conducted to compare the clinical stage derived from 2-deoxy-2-[F-18]fluoro-d-glucose (FDG) positron emission tomography (PET) to that of integrated PET/computed tomography (CT) in restaged breast cancer patients.ProceduresFifty-eight female patients (age range 29–80 years, mean age ±SD, 53.3 ± 11.7 years) underwent PET/CT restaging for breast cancer. Two experienced nuclear medicine physicians interpreted PET images. A radiologist was added for reading PET/CT studies. A patient-based analysis was performed. Histopathological findings, correlative imaging studies, changes in number, size, and hypermetabolic activity of suspicious lesions and/or patient outcome served as standard of reference for determining the diagnostic accuracy of both modalities.ResultsPET staged 79.3% (46/58) of the patients correctly, overstaged seven (12.1%), and understaged five patients (8.6%). Integrated PET/CT staged 89.7% (52/58) of the patients correctly, overstaged four (6.9%), and understaged two patients (3.4%). The staging accuracy of PET/CT was not significantly better than that of PET alone (p = 0.059). Lesions exhibiting mild hypermetabolic activity, benign inflammatory lesions, and physiological variants largely explained incorrect PET findings.ConclusionIntegrated PET/CT only marginally improves the restaging accuracy over PET alone (p = 0.059) in breast cancer patients.

Dual-Time-Point FDG-PET/CT for the Detection of Hepatic Metastases

PurposeTo prove the sensitivity of dual-time-point imaging with 18F-flourodeoxyglucose-positron emission tomography (18F-FDG-PET) of the liver to evaluate possible changes in the tumor-to-background ratio considering an improved detection rate of liver lesions.ProceduresImage acquisition for the first whole-body scan started at a mean time point of 69 min (55–110 min). The mean time interval between the injection of 18F-FDG and the second delayed scan was 100 min (85–166 min).ResultsOf 90 proven liver metastases in 34 patients, the first scan detected 53 (59%) liver lesions correctly, whereas in the second, delayed scan 81 (90%) lesions were diagnosed correctly (p<0.001). The mean Standardized uptake values in the first and second delayed scan were 6.59 g/ml versus 8.09 g/ml, respectively (p<0.001). Tumor-to-background ratio of the first and second delayed scan were 2.0 and 2.7, respectively (p = 0.04).ConclusionsDual-time-point-imaging of the liver showed a significant increase of tumor-to-background ratio and hypermetabolic lesion diameter. Although, 30% of all verified liver lesions could only be detected in the second delayed scan 10% of all malignant liver lesions were missed with FDG-PET.