Modeling regional myocardial flows from residue functions of an
intravascular indicator.
Kroll, K., N. Wilke, M. Jerosch-Herold, Y. Wang, Y. Zhang, R. J.
Bache, and J. B. Bassingthwaighte.
Center for Bioengineering, University of Washington, Seattle, WA
98195, Department of Radiology, and Cardiovascular Division,
University of Minnesota, Minneapolis, MN 55416
APStracts 3:0140H, 1996.
The purpose of the present study was to determine the accuracy and the
sources of error in estimating regional myocardial blood flow and
vascular volume from experimental residue functions obtained by
external imaging of an intravascular indicator. For the analysis, a
spatially distributed mathematical model was used that describes
transport through a multiple pathway vascular system. Reliability of
the parameter estimates was tested using sensitivity function
analysis, and by analyzing "pseudodata": realistic model
solutions, to which random noise was added. Increased uncertainty in
the estimates of flow in the pseudodata was observed when flow was
near maximal physiological values, when dispersion of the vascular
input was more than twice the dispersion of the microvascular system
for an impulse input, and when the sampling frequency was less than
two samples per second. Estimates of regional blood volume were more
reliable than estimates of flow. Failure to account for normal flow
heterogeneity caused systematic underestimates of flow. To illustrate
the method used for estimating regional flow, magnetic resonance
imaging (MRI) was used to obtain myocardial residue functions
following left atrial injections of Polylysine-Gd-DTPA, an
intravascular contrast agent, in anesthetized chronically
instrumented dogs. To test the increase in dispersion of the vascular
input following central venous injections, MRI data obtained in human
subjects were compared to left ventricular blood pool curves obtained
in dogs. It is concluded that if coronary flow is in the normal
range, when the vascular input is a short bolus, and the heart is
imaged at least once per cardiac cycle, then regional myocardial
blood flow and vascular volume may be reliably estimated by analyzing
residue functions of an intravascular indicator, providing a
noninvasive approach with potential clinical application.
Received 15 December 1994; accepted in final form 19 March 1996.
APS Manuscript Number H1093-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 16 April 96