TY - JOUR T1 - Validation of scatter correction with combined single-scatter simulation and Monte Carlo simulation scaling to quantify myocardial blood flow on <sup>15</sup>O-water PET JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1723 LP - 1723 VL - 59 IS - supplement 1 AU - Keiichi Magota AU - Tohru Shiga AU - Osamu Manabe AU - Masanao Naya AU - Tadao Aikawa AU - Daiki Shinyama AU - Dennis Heijtel AU - Kenji Hirata AU - Chietsugu Katoh AU - Marc Huisman AU - Ronald Boellaard AU - Katsuhisa Fujita AU - Adriaan Lammertsma AU - Nagara Tamaki Y1 - 2018/05/01 UR - http://jnm.snmjournals.org/content/59/supplement_1/1723.abstract N2 - 1723Objectives: 15O-water PET imaging is considered to be the gold standard for the quantitative assessment of myocardial blood flow (MBF). Recently, a novel scatter correction method was developed, in which single-scatter simulation (SSS) is combined with Monte Carlo simulation (MC-SSS) for calculating the scaling factor (1). MC-SSS prevents artifact generation induced by the spatial misregistration between emission and transmission images on the traditional tail-fitting approach (1,2). However, the impact of MC-SSS on quantification of 15O-water derived MBF is not known. In the present study, MC-SSS was applied to clinical 15O-water based MBF studies and results were compared with those obtained using the conventional scatter correction method (SSS with tail-fitting scaling [TF-SSS]). Methods: Thirty-one patients (67±12 years, 26 males) with known or suspected coronary artery disease underwent dynamic 15O-water PET to measure MBF both at rest and at pharmacological stress. Data were acquired on a Gemini TF PET/CT scanner (Philips). List-mode data were binned into 24 serial frames (18×10 and 6×30 s), and reconstructed using a 3D-row action maximum-likelihood algorithm both with TF-SSS and MC-SSS scatter correction. MBF and coronary flow reserve (CFR) were calculated for whole heart and three coronary artery territories (left anterior descending [LAD], right coronary artery [RCA], and left circumflex [LCX]) using the standard single-tissue compartment model. Average MBF and CFR values based on TF-SSS and MC-SSS images, and their difference, correlation, and Bland-Altman 95% limits of agreement (LoA) were assessed for whole heart and each coronary artery territory. Results: Figure 1 shows image profiles of a typical patient both at early and late phases. There were no differences between TF-SSS and MC-SSS in the reconstructed images. Mean resting MBF for whole heart was 1.00±0.21 and 0.99±0.21 mL/min/g for TF-SSS and MC-SSS, respectively. Stress MBF was 2.36±0.79 and 2.32±0.76 mL/min/g, respectively, and consequently CFR was 2.46±0.95 and 2.48±0.95, respectively. The difference between MC-SSS and TF-SSS was −0.01±0.02 mL/min/g for resting MBF (r=0.996, p&lt;0.05, LoA=−0.05 to 0.03 mL/min/g), −0.04±0.10 for stress MBF (r=0.993, p&lt;0.05, LoA=−0.24 to 0.15), and −0.00±0.09 for CFR (r=0.996, p=0.97, LoA=−0.17 to 0.17). Table summarizes results for all coronary artery territories. Rest and stress MBF values based on MC-SSS showed a small but significant underestimation in LAD and LCX. However, differences cancelled out in calculating stress-to-rest ratios, i.e. CFR. The slope of the scatter diagram for all coronary artery territories was close to 1.0 and the intercept was close to zero (Figs. 2A and 2B), thus indicating excellent correlation between TF-SSS and MC-SSS over a broad range of MBF and CFR values (MBF: y = 0.97x+0.03, r=0.996; CFR: y = 0.99x+0.02, r=0.992). Even for CFR values below 2.0, correlation between TF-SSS and MC-SSS was excellent (y = 0.98x+0.03, r=0.996). Conclusions: Quantification of MBF using MC-SSS images was validated against TF-SSS images in patients with known or suspected coronary artery disease. MC-SSS derived MBF estimates were found to be accurate over a broad range of MBF values. Therefore, MC-SSS could be implemented for routine clinical use. View this table:Absolute MBF and CFR with their difference, correlation, and Bland-Altman 95% limits of agreement ER -