Table 1. Microvascular network architecture quantitative metrics.

Metric	Unita	Description	Potential biological relevance
Vessel area density (VAD)	%	Perfused blood vessel area in binarized OCTA MIP image divided by total image area	Indicates utilization of microvessels. Increased VAD is associated with angiogenesis
Vessel length density (VLD)	%	Total length of perfused vessels measured along the vessel centerline divided by the total image area. Length measurements are calculated from the skeletonized OCTA MIP image	Indicates oxygenation/nutrient delivery dysfunction. Increased VLD is associated with angiogenesis
Average and distribution of vessel diameter	μm	Diameter measurements acquired using a local thickness algorithm in ImageJ applied to the binarized OCTA MIP	Reveals information about dilation and regression; the distribution allows further differentiation between changes in diameter and number of perfused vessels
Average and distribution of vessel length	mm	Length of each identified vessel segment along the centerline of the vessel calculated from the skeletonized OCTA MIP image	Network interconnectivity and branching patterns indicates oxygenation/nutrient delivery dysfunction
Average and distribution of tortuosity	1	Segment length along the centerline divided by chord length for each identified vessel calculated from the skeletonized OCTA MIP image	Increased blood vessel tortuosity can indicate pathological microvascular remodeling and/or ischemia
Branchpoint density	Nodes/mm	Number of identified nodes divided by total vessel length	Network interconnectivity-based indicator of resistance to blockage or occlusion and flow dynamics
Fractal dimension	1	Indication of how the network fills space on variable length scales, calculated using the box counting method	Indicator of branching architecture within the network; indicator of tortuosity and microvascular remodeling

^aA unit of 1 indicates a dimensionless metric.