Table 3.

Spatial distribution of terminal precapillary flow rate and perfusion density for a coronary subtree

Axial Position	Subepicardium		Midwall		Subendocardium		Qendo/Qepi
Base	1.42 ± 1.08	0.50	1.27 ± 1.31	0.61	1.02 ± 0.79	0.62	1.22
Center	1.40 ± 1.03	0.50	1.27 ± 1.31	0.61	0.96 ± 0.77	0.58	1.16
Apex	1.40 ± 1.14	0.50	1.27 ± 0.63	0.61	0.79 ± 0.95	0.48	0.96

The table lists the mean ±  SD values of terminal precapillary flow rate (q_term) (q_term × 10⁻³ mm³/s), perfusion density (Q) (Q × mm³/s), and the ratio of perfusion densities in the subendocardium and subepicardium (Q_endo/Q_epi); n = 8,634 vessels. Q in different transmural regions is calculated from q_term multiplied by the terminal arteriole density of 355 in subepicardium, 480 in the midwall, and 603 in the subendocardium, respectively. The ratio of arteriolar densities in the subendocardium vs. subepicardium is 1.7 and 1.35 in the midwall vs. subepicardium, which are close to the measured arterial volumes in these regions (42, 89).