## Abstract

Methods for estimating regional flow from digital angiography or dynamic computed tomography images require determination of indicator mean transit time ( {Mathematical expression}) through a region-of-interest (ROI). We examine how the ROI kinematics and input dispersion influence the recovery of {Mathematical expression} using a computer-simulated vessel network representing that which might occur in a real organ. The network simulates flow through a large artery branching into two small arteries, each feeding a system of smaller vessels intended to represent capillaries and small vessels below the resolution of the imaging system. The capillaries are drained by a similar system of veins. Concentration curves measured over the inlet to the network and microvascular ROI residue curves are simulated. When the area-height ratio of the microvascular ROI curve is used and all of the indicator is contained within the ROI for at least one time point, {Mathematical expression} is recovered exactly. As the size of the ROI is reduced or the inlet concentration curve becomes more dispresed, the error in the recovery of {Mathematical expression} grows. By first deconvolving the inlet concentration curve from the microvascular ROI curve, and then calculating the area-height ratio, {Mathematical expression} is recovered accurately. If the inlet concentration curve becomes more dispersed between its measured site and the actual inlet to the ROI, or if the flow distribution within the ROI is changed, the estimation of {Mathematical expression} can be degraded. To put the simulations in perspective relative to an example of image data, the methods were applied to microfocal x-ray angiography data obtained from a ⊃700 μm canine pulmonary artery and vein, the surrounding microvasculature and the inlet lobar arterial cannula.

Original language | English (US) |
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Pages (from-to) | 128-143 |

Number of pages | 16 |

Journal | Annals of Biomedical Engineering |

Volume | 22 |

Issue number | 2 |

DOIs | |

State | Published - Mar 1994 |

## Keywords

- Digital angiography
- Mean transit time
- Pulmonary circulation
- Residue detection

## ASJC Scopus subject areas

- Biomedical Engineering