TY - JOUR T1 - The Evaluation of Sex-Specific Differences in Myocardial Blood Flow, Myocardial Flow Reserve and Hemodynamic change under Caffeine Intake by <sup>99m</sup>Tc-sestamibi Dynamic SPECT/CT JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1672 LP - 1672 VL - 62 IS - supplement 1 AU - Hung-Pin Chan AU - Chin Hu AU - Ming-Hui Yang AU - Nan-Jing Peng Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/62/supplement_1/1672.abstract N2 - 1672Introduction: Caffeine decreased myocardial blood flow (MBF) and myocardial flow reserve (MFR) of LV by dipyridamole-induced vasodilation, and yielded false positive results in PET studied. It had similar results of our previous study demonstrated by Dynamic SPECT/CT. The purpose of this study is to investigate the sex difference under caffeine intake on Dynamic SPECT/CT in our patients. Methods: Totally 57 patients was enrolled suspected CAD (32 patients) or abnormal CT angiography (CTA) (25 patients) in this study, including women (22 patients) and men (35 patients) that divided into 3 groups randomly: (1) 72 hours caffeine abstinence before study (non-caffeine group); (2) &lt;24 hours caffeine intake group (one caffeine tablet, about 200 mg); (3) more 24 hours Caffeine intake group. Rest (13 mCi 99mTc-sestamibi; MIBI)/dipyridomale-stress (30 mCi MIBI) Dynamic SPECT/CT one day protocol with gated SPECT performed on a dedicated Siemens Symbia-T2 SPECT/CT system. . The quantitative data was analyzed by MyoFloQ software. Statistical analysis was performed with commercially available soft ware (SPSS) and P &lt;0.05 was considered statistically significant. Results: Interesting, we found the rest blood flow of LV in women (1.15±0.2 ml/min/g) “higher” than in men (0.96±0.2 ml/min/g) with statistically significant (P&lt;0.01), including in LAD, RCA, or LCx territories, respectively. Women had “higher” stress ejection fraction (EF; 73%±12%) and rest EF (69%±14%) than men (stress EF 63%±10%, rest EF 58%±11%) (P&lt;0.01). Difference of stress EF and rest EF presented women “lower” than men but no statistically significant. Stress blood flow, myocardial flow reserve, and stress hear rate/ rest heart rate (HRR) had no difference between women and men. Caffeine intake &lt; 24 hours decreased MBF and MFR, but no influence &gt; 24 hours caffeine intake on both groups. Caffeine reduced “less” sMBF and MFR in disease vessels (&gt;50% stenosis or positive PCI results) by caffeine, as compared with those in non-disease vessels that similar effects on both groups. Conclusions: Compared to men, women have higher rest blood flow, stress EF and rest EF on Dynamic SPECT/CT that that indicated female sex maybe a predictor of these sex-specific differences in coronary physiology. No difference of stress blood flow, MFR, difference EF, and HRR was noted between both groups. No matter man or women could be reduced less sMBF and MFR in disease vessels by caffeine, as compared in non-disease vessels. ER -