Objective To evaluate the diagnostic value of quantitative rest and stress 13N-NH3 PET myocardial perfusion imaging (MPI) on coronary microvascular disease (CMVD),and provide basis for accurate classification.Methods From July 2016 to September 2017,a total of 23 patients (16 males,7 females;27-70 years) who were suspected of CMVD were prospectively enrolled in this study.Rest and ATPstress MPI were acquired using 13N-NH3 PET and analyzed using 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.Based on the information,CMVD was diagnosed or excluded.Combined with myocardial enzymes,echocardiography,cardiac MRI,coronary angiography,CT angiography (CTA),CMVD was further divided into CMVD without (type 1) or with obstructive coronary disease (type 2),and other CMVD (type 3).Two-sample t test and one-way analysis of variance were used to analyze the data.Results In 23 patients,17 cases were diagnosed as CMVD (including 10 cases with type 1,3 cases with type 2 and 4 cases with type 3),and 6 cases were excluded.There were no significant differences in the age,gender and risk factors between CMVD group and exclusion group (all P＞0.05).The relative uptake results,including average uptake of whole left ventricle in rest and stress states,rest minimum quadrant,and area of stress uptake less than 60％ of maximum were significantly different between the two groups (t values:from -3.249 to 2.469,all P＜0.05).All the absolute blood flow parameters,including rest and stress whole MBF and CFR,rest and stress minimum quadrant MBF and CFR,were significantly different between CMVD group and exclusion group (t values:from-8.278 to-3.258,all P＜0.05).There was no statistically significant difference for relative uptake data among three types of CMVD (F values:from 0.002 to 1.440,all P＞0.05).For absolute quantitative values of whole MBF and minimum quadrant MBF in both rest and stress states,difference was statistically significant among groups (F values:from 3.885 to 8.452,all P＜0.05).Conclusion Quantitative PET MPI could provide a noninvasive,safe and accurate method for the diagnosis and classification of CMVD.