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Objective: (18F-fluoropentyl)triphenylphosphonium salt (18F-FPTP) is a new promising myocardial PET imaging tracer. It shows high accumulation in cardiomyocytes and rapid clearance from liver. We performed compartmental analysis of 18F-FPTP PET images in rat and evaluated two linear analyses: linear least-squares (LLS) and a basis function method (BFM) for generating parametric images. The minimum dynamic scan duration for kinetic analysis was also investigated and computer simulation undertaken.Methods: 18F-FPTP dynamic PET (18 min) and CT images were acquired from rats with myocardial infarction (MI) (n = 12). Regions of interest (ROIs) were on the left ventricle, normal myocardium, and MI region. Two-compartment (K 1 and k 2; 2C2P) and three-compartment (K 1-k 3; 3C3P) models with irreversible uptake were compared for goodness-of-fit. Partial volume and spillover correction terms (V a and α = 1 - V a ) were also incorporated. LLS and BFM were applied to ROI- and voxel-based kinetic parameter estimations. Results were compared with the standard ROI-based nonlinear least-squares (NLS) results of the corresponding compartment model. A simulation explored statistical properties of the estimation methods.Results: The 2C2P model was most suitable for describing 18F-FPTP kinetics. Average K 1, k 2, and V a values were, respectively, 6.8 (ml/min/g), 1.1 (min-1), and 0.44 in normal myocardium and 1.4 (ml/min/g), 1.1 (min-1), and 0.32, in MI tissue. Ten minutes of data was sufficient for the estimation. LLS and BFM estimations correlated well with NLS values for the ROI level (K 1: y = 1.06x + 0.13, r 2  = 0.96 and y = 1.13x + 0.08, r 2  = 0.97) and voxel level (K 1: y = 1.22x - 0.30, r 2  = 0.90 and y = 1.26x + 0.00, r 2  = 0.92). Regional distribution of kinetic parametric images (αK 1, K 1, k 2, V a) was physiologically relevant. LLS and BFM showed more robust characteristics than NLS in the simulation.Conclusions: Fast kinetics and highly specific uptake of 18F-FPTP by myocardium enabled quantitative analysis with the 2C2P model using only the initial 10 min of data. LLS and BFM were feasible for estimating voxel-wise parameters. These two methods will be useful for quantitative evaluation of 18F-FPTP distribution in myocardium and in further studies with different conditions, disease models, and species. [ABSTRACT FROM AUTHOR]

Purpose: The presence of central lymph node (LN) metastasis increases the risk of cervical LN recurrence or distant metastasis in patients with papillary thyroid microcarcinoma (PTMC). We investigated the value of preoperative F-fluoro-2-deoxy- d-glucose-positron emission tomography (FDG PET)-computerized tomography (CT) and ultrasonography (US) to predict central LN metastasis from PTMC. Patients and methods: Two hundred patients with newly diagnosed unifocal PTMC were enrolled. Preoperative FDG PET-CT was performed, and the highest SUV (SUV) of focally increased uptake at thyroid was measured. Tumor size was measured using preoperative US. Uni- and multivariate analyses were performed using the presence of focally increased uptake at thyroid (FDG positivity), SUV, tumor size, and clinical risk factor for central LN metastasis. ROC curves for risk factors were then analyzed. These analyses were undertaken in two groups: the all patients group and the FDG-positive group. Finally, we combined risk factors associated with central LN metastasis to improve predictive accuracy. Results: Tumor size >6 mm was associated with central LN metastasis. FDG positivity was identified in 110 patients (55.0 %) and the SUV ranged from 1.8 to 12.8 (median 3.0). In FDG-positive group, SUV >2.8 was associated with central LN metastasis. Addition of SUV >2.8 to size >6 mm of PTMC improved sensitivity of predicting central LN metastasis from 55.0 to 67.5 %, while specificity remained at 70.6 %. Conclusion: Both FDG PET-CT and US are valuable for preoperative prediction of central LN metastasis from PTMC. Combined use of SUV and tumor size improves sensitivity without changing specificity. [ABSTRACT FROM AUTHOR]