the effect of timeofflight and point spread function modeling on 82 background the effect of timeofflight tof and point spread function psf modeling in image reconstruction has not been well studied for cardiac pet this study assesses their separate and combined influence on 82rb myocardial perfusion imaging in obese patientsmethods thirtysix obese patients underwent reststress 82rb cardiac pet images were reconstructed with and without tof and psf modeling perfusion was quantitatively compared using the aha 17segment model for patients grouped by bmi crosssectional body area in the scanner field of view gender and left ventricular myocardial volume summed rest scores srs summed stress scores sss and summed difference scores sds were comparedresults tof improved polar map visual uniformity and increased septal wall perfusion by up to 10 this increase was greater for larger patients more evident for patients grouped by crosssectional area than by bmi and more prominent for females psf modeling increased perfusion by about 15 in all cardiac segments tof modeling generally decreased srs and sss with significant decreases between 24 and 30 p05 which could affect risk stratification sds remained about the same with psf modeling srs sss and sds were largely unchangedconclusion tof and psf modeling affect regional and global perfusion srs and sss clinicians should consider these effects and genderdependent differences when interpreting 82rb perfusion studies