This　study　aimed　to　examine　whether　the　ratio　of　vessel-specific　coronary　arterial　lumen　volume　to　the　fraction　of　myocardial　mass　(V-R/M-R)　affects　myocardial　ischemia.　We　proposed　a　calculation　method　for　V-R/M-R,　and　compared　the　ratio　of　total　epicardial　coronary　arterial　lumen　volume　to　left　ventricular　myocardial　mass　(V/M)　with　V-R/M-R　in　predicting　myocardial　ischemia.　V-R/M-R　and　V/M　were　computed　using　data　from　205　patients　with　241　stenosis　vessel　who　underwent　coronary　computed　tomography　angiography　(CTA),　quantitative　coronary　angiography,　and　fractional　flow　reserve.　The　vessel-specific　coronary　arterial　lumen　volume　(V-R)　was　obtained　from　CTA　by　segmenting　the　coronary　arterial　lumen　volume,　while　the　vessel-specific　fraction　of　myocardial　mass　(M-R)　was　obtained　by　allometric　scaling.　The　V-R/M-R　was　then　calculated.　The　cut-off　values　of　V/M　(23.55　mm(3)/g)　and　V-R/M-R　(12.98　mm(3)/g)　were　used　to　define　equal　groups　of　ischemic　and　non-ischemic　patients,　respectively.　Using　these　cut-off　values,　the　accuracy,　specificity,　sensitivity,　positive　predictive　value,　and　negative　predictive　value　of　V/M　were　60%,　76%,　45%,　57%,　and　66%,　and　of　V-R/M-R　were　87%,　92%,　77%,　89%,　and　83%,　respectively.　Patients　have　different　V-R/M-R　values　in　different　stenotic　coronary　arteries.　Clinically,　V-R/M-R　is　a　quantitative　indicator　of　the　risk　of　myocardial　ischemia.