ABSTRACT
PURPOSE: The administration accuracy of the automated infusion device for the positron emission radiopharmaceutical affects to calculation of the standardized uptake value (SUV) in 18F-fluorodeoxyglucose (18F-FDG) PET examination. The purpose of this study was to investigate the administration error in the clinical use of an automated infusion device for quantitative management in PET examination. METHODS: We assumed clinical use of the automated infusion device and investigated two types of administration errors. First, for investigating the administration error over time in a day (errorday), a total of 13 infusion works were performed every 30 minutes. Second, for investigating the long period administration error (errorperiod), the infusion work was performed once before clinical use of an automated infusion device. The dispensed radioactivity was set to 150 MBq. The administration error was calculated using output values from the automated infusion device and measured values from the dose calibrator. RESULTS: The administration errorday was 0.9±1.3%, and the maximum error was 2.7%. The administration errorperiod was 1.1±2.0%, and the maximum error was 5.9%. CONCLUSION: We investigated the administration error of the automated infusion device. We confirmed the approximately 1% administration error and high-accuracy injection in an automated-device method.
Subject(s)
Fluorodeoxyglucose F18 , Positron-Emission Tomography , Injections , RadiopharmaceuticalsABSTRACT
BACKGROUND: The amount of signal decreases when the acquisition duration is shortened. However, it is not clear how this affects the quantitative values. This study aims to clarify the effect of acquisition time shortening in brain tumor PET/CT using 11C-methionine on the quantitative values. METHOD: This study was a retrospective analysis of 30 patients who underwent clinical 11C-methionine PET/CT examination. PET images were acquired in list mode for 10 min. PET images of acquisition duration from 1 to 10 min with 1-min step were reconstructed. We examined the effect on the quantitative values of acquisition duration. We placed a volume of interest to include the entire tumor and regions of interest in the shape of a large crescent in the contralateral hemisphere in 5 contiguous axial slices as normal tissue. Quantitative values examined were maximum, peak, and mean standardized uptake values (SUVmax, SUVpeak, SUVmean), metabolic tumor volume (MTV), and maximum tumor to normal tissue ratio (TNRmax), with each duration compared to that with 10 min. RESULTS: SUVmax, MTV, and TNRmax showed the highest values due to the effects of statistical noise when the acquisition time was 1 min. These values were stable when the acquisition duration was > 6 min. SUVpeak and SUVmean showed mostly consistent values regardless of duration. CONCLUSIONS: SUVmax, MTV, and TNRmax are affected by acquisition time. If the acquisition duration was > 6 min, the fluctuation could be suppressed within 5% in these quantitative values. However, SUVpeak was suggested to be a robust index regardless of the acquisition duration.
ABSTRACT
OBJECTIVE: Cartilage invasion in laryngohypopharyngeal cancer has a significant impact on the choice of treatment modality and outcome of the disease. We examined invasion of cartilage in laryngohypopharyngeal cancer by simultaneous bone and tumor dual-isotope SPECT using 99mTc-hydroxymethylene diphosphonate and 201Tl-chloride. METHODS: Early and delayed simultaneous bone and tumor dual-isotope SPECT were performed on 19 patients with laryngohypopharyngeal cancer. Dual-isotope SPECT images were superimposed to project tumor location from tumor SPECT onto the osseous structures shown by bone SPECT. The presence or absence of cartilage invasion was evaluated histopathologically or by radiological studies such as CT and/or MRI. RESULTS: Histopathological or radiological examination of the cartilage revealed invasion in 5 patients and no invasion in 14 patients. The results of both early and delayed dual-isotope SPECT were exactly the same. Using dual-isotope SPECT, the sensitivity, specificity, and accuracy in detecting cartilage invasion by laryngohypopharyngeal cancer were: 80% (4/5), 92.9% (13/14), and 89.5% (17/19), respectively. CONCLUSIONS: Results of the present study suggest that superimposed early bone and tumor dual-isotope SPECT images may be sufficient for the diagnostic evaluation of cartilage invasion by laryngohypopharyngeal cancer. Superimposed dual-isotope SPECT imaging is a useful technique in the evaluation of cartilage invasion in laryngohypopharyngeal cancer.
