From: A guide to human in vivo microcirculatory flow image analysis
Microcirculation parameter | Information provided | Symbol/equation | Units | Measurement | References |
---|---|---|---|---|---|
Microvascular flow index | Perfusion quality (for small, medium, and large vesselsa) | MFI | Arbitrary | The image is divided into four quadrants; a number is assigned for each quadrant according to the predominant type of flow (0 = no flow; 1 = intermittent; 2 = sluggish; 3 = continuous). The MFI results from the averaged values | |
De Backer score | Vessel density | \( \mathrm{V}{{\mathrm{D}}_{De}}_{Bac \ker}\kern0.5em =\kern0.5em Nx/L\mathit{\mathsf{g}} \) | 1/mm | The image is divided by three vertical and three horizontal lines; the De Backer score is calculated as the number of vessels crossing the lines divided by the total length of the lines | |
Total vessel density | Vessel density (for small, medium, and large vesselsa) | TVD = L v /A FOV | mm/mm2 | Total length of vessels is divided by the total surface of the analyzed area | |
Proportion of perfused vessels (by length) | Perfusion quality (for small, medium, and large vesselsa) | PPV1 = L p /L v | Percent | 100 × number of perfused vessels is divided by the total number of vessels | |
Proportion of perfused vessels |  | PPV = N p /N v | Percent | 100 × length of perfused vessels divided by total length of vessels | [7] |
Flow heterogeneity index | Perfusion heterogeneity | FHI = (MFI max  − MFI min )/MFI avg | Unitless | The difference between the highest MFI and the lowest MFI is divided by the mean MFI. MFI is intended as the averaged MFI of each site | |
Perfused vessel density |  | PVD = PPV * VDDe Backer | 1/mm | Vessel density × proportion of perfused vessels | [41] |
Perfused vessel density | Functional vessel density (for small, medium, and large vesselsa) | \( \begin{array}{l}\mathrm{P}\mathrm{V}\mathrm{D}\kern0.5em =\kern0.5em {L}_p/{A}_{FOV}\kern0.5em \mathrm{or}\kern0.5em \\ {}\mathrm{P}\mathrm{V}\mathrm{D}\kern0.5em =\kern0.5em \mathrm{P}\mathrm{P}{\mathrm{V}}_1\kern0.5em *\kern0.5em \mathrm{T}\mathrm{V}\mathrm{D}\end{array} \) | mm/mm2 | Total length of perfused vessels (sluggish or continuous) is divided by the total surface of the analyzed area (%) |