Impact of timeofflight on qualitative and quanti

Authors: Takeshi Tomiyama Keiichi Ishihara Masaya Suda Koji Kanaya Minoru Sakurai Naoto Takahashi Hitoshi Takano Koichi Nitta Kenta Hakozaki Shinichiro Kumita

Publish Date: 2014/12/03

Volume: 22, Issue: 5, Pages: 998-1007

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Abstract

Twenty consecutive subjects underwent rest and adenosine stress 13Nammonia myocardial perfusion PET Two sets of images were reconstructed using TOFordered subset expectation maximization TOFOSEM and 3dimensional rowaction maximum likelihood algorithm 3DRAMLA Qualitative and quantitative analyses from the TOFOSEM and 3DRAMLA reconstructions were compared Count profile curves revealed that TOF relatively increased the uptake of 13Nammonia at the lateral walls and apical thinning was emphasized on the TOF images Both segmental rest and stress myocardial blood flow MBF values were higher with TOFOSEM use than with 3DRAMLA use rest MBF 0955 ± 0201 vs 0836 ± 0185 P  001 stress MBF 2149 ± 0697 vs 2058 ± 0721 P  001 The differentiation of MBF between reconstructions was more enhanced under rest conditions Thus segmental myocardial flow reserve MFR observed using TOFOSEM reconstruction was lower than that observed using 3DRAMLA 225 ± 057 vs 246 ± 075 P  001 No remarkable differences were observed between segmental and territorial results13Nammonia myocardial perfusion positron emission tomography PET can quantitatively evaluate the absolute rest and stress myocardial blood flow MBF and myocardial flow reserve MFR As coronary stenosis increases in severity both stress MBF and MFR reduce1 MFR changes also occur because of microvascular and vascular endothelial dysfunctions caused by hypertension diabetes mellitus dyslipidemia or smoking25 Quantitative analysis in addition to a visual assessment improves the detection of chronic coronary artery disease CAD6 Furthermore absolute MBF is useful for stratifying the risk of major adverse cardiac events and cardiac death and predicting a longterm prognosis79 13Nammonia PET can provide excellent images with few artifacts However because accumulation of 13Nammonia in the lateral wall is about 10 lower than that in other segments even in healthy subjects special attention is needed during interpretation10Timeofflight TOFPET/CT scans can measure the time difference between the detection of two 511 keV annihilation photons TOF focuses on localizing events along coincidence lineofresponse and improves the signaltonoise ratio An improvement in the signaltonoise ratio and detectability has also been reported with wholebody oncologic PET1112 However the impact of TOF on myocardial perfusion and quantification of MBF with 13Nammonia PET has not yet been investigated As such the aim of this study was to assess the effect of TOF on qualitative and quantitative analyses of myocardial perfusion 13Nammonia PET

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