Abstract
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Objectives: PET is regarded as gold standard for noninvasive measurement of coronary flow reserve (CFR). The objective of this study was to evaluate the diagnostic value of quantitative rest and stress 13N-NH3 PET myocardial perfusion imaging (MPI) on coronary microvascular disease (CMVD),and to provide information for accurate classification of CMVD.
Methods: From July 2016 to December 2017, a total of 36 patients who were suspected of CMVD (28 males, 8 females; 27-70 years) were prospectively enrolled in this study. Rest and ATP-stress MPI were acquired using 13N-NH3 PET and analyzed with Heartsee software. Rest and stress relative uptake, absolute myocardial blood flow (MBF) and coronary flow reserve (CFR) were obtained and present on sectional images and cup maps. For relative uptake, percent of the whole topographic image with relative activity <60% of maximum activity (< 60% of maximum (% of LV)), average uptake of whole left ventricle (relative uptake mean), and the value in the quadrant with the lowest average uptake (minimum quadrant average) were analyzed. For absolute quantification, rest and stress whole LV MBF, minimum quadrant average MBF, whole LV CFR and minimum quadrant CFR were analyzed. Based on the information, CMVD was diagnosed or excluded. Integrated with myocardial enzymes, echocardiography, cardiac MR, coronary angiography, CT angiography (CTA), etc., CMVD was further divided into 3 categories, CMVD without occlusive coronary disease (type 1), CMVD with obstructive coronary disease (type 2), and other types of CMVD (type 3). Fisher's exact test, two-sample t-tests and one-way analysis of variance were used to analyze the data. Results: In 36 patients, 27 cases were diagnosed as CMVD (including 14 cases with type 1, 9 cases with type 2 and 4 cases with type 3), and 9 cases were excluded CMVD. There were no significant differences in the age, gender and risk factors (diabetes mellitus, dyslipidemia, hypertension, current or past tobacco use, alcohol drinking) between CMVD group and exclusion group (all P>0.05). For relative uptake, although rest and stress percent of < 60% of maximum in CMVD group were greater than those in exclusion group (P<0.05, with T values of -2.736 and -3.440); rest and stress relative uptake mean, and rest minimum quadrant average in CMVD group were lower than those in exclusion group (all P<0.05, T = 2.494, 4.444 and 2.457), all the results have high standard variation; no significant difference is observed between CMVD group and exclusion group in stress minimum quadrant average (P=0.107, T=1.654). For absolute quantification, stress whole LV MBF and CFR, stress minimum quadrant MBF and CFR in CMVD group were significantly lower than those in exclusion group (all P<0.05,T = 7.032, 5.965, 7.068, and 6.381), whereas there was no significant difference between CMVD group and exclusion group in rest whole MBF and rest minimum quadrant MBF (P>0.05,T = 1.807 and 1.883). For three types of CMVD, there is no statistically significant difference among groups in all relative uptake data ( all P>0.05,F = 0.042, 0.084, 0.010, 0.408, 0.177 and 0.188); the rest and stress whole LV MBF and minimum quadrant average MBF are statistically significant different among groups (all P<0.05,F = 5.383, 9.947, 5.109 and 13.656), no significant difference is observed in whole LV CFR and minimum quadrant CFR among groups (P>0.05,F = 1.967 and 2.445). Typical image of three types of CMVD are shown in Supporting Figure. Conclusion: Quantitative PET MPI could provide a noninvasive, safe and accurate method for the diagnosis and classification of CMVD. Acknowledgment: This work was supported by the Clinical Research Physician Program of Tongji Medical College, Huazhong University of Science and Technology (No. 5001530008).
