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Updated: Jul 2, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
First-pass dynamic contrast-enhanced MRI with extravasating contrast reagent: evidence for human myocardial capillary
Xin Li1, Charles S Springer, Michael Jerosch-Herold
1Advanced Imaging Research Center, Oregon Health & Science University, Portland, OR 97239, USA. lxin@ohsu.edu
Abstract:
Human myocardial (1)H(2)O T(1)-weighted dynamic contrast-enhanced MRI data were acquired during the brief first-pass period after injection of a very small gadolinium diethylenetriaminepenta-acetate (GdDTPA(2-)) dose. The shutter-speed pharmacokinetic effects of both transendothelial and transcytolemmal equilibrium water exchange processes were investigated. Our results indicate that even for such a short acquisition window and relatively large pseudo-first-order rate constant (K(trans)) for plasma/interstitium contrast reagent (CR) transfer the kinetics of these water exchange processes cannot be treated as infinitely fast or slow. However, neither the intracellular water molecule lifetime (tau(i)) nor its intravascular counterpart (tau(b)) are among the parameters most influential in analysis of the noisy data typically associated with the cardiac perfusion application. Thus, the actual values of water exchange kinetic rate constants are relatively indeterminate as this experiment is usually conducted. Combining the K(trans) evaluations with independently determined flow (F) values allows us to estimate CR permeability coefficient surface area product (P(CR)S) values. The fact that the P(CR)S magnitudes almost equal the K(trans) values confirms that GdDTPA(2-) extravasation in resting human myocardial muscle is indeed permeation-limited and supports the validity of the K(trans) and P(CR)S estimations. Nevertheless the model analysis is most consistent with the results if P(CR)S is not assumed to be constant with changing flow. The capillary blood volume fraction (v(b)) is a sensitive parameter in the analysis. We also compared resting and hyperemic cardiac conditions, the latter resulting from the volume flow increase induced by adenosine arteriolar vasodilation. We found that the P(CR)S value increases with flow probably mostly because of an S increase associated with capillary recruitment. The v(b) values also increased in hyperemia and showed a flow-dependence with a clearly identifiable component due to capillary recruitment.
Insights
Investigating human myocardial contrast-enhanced MRI, this study reveals that water exchange kinetics are complex. While contrast reagent transfer is permeation-limited, its permeability-surface area product increases with flow due to capillary recruitment.
Area of Science:
- Cardiovascular Imaging
- Pharmacokinetics
- Biophysics
Background:
- Dynamic contrast-enhanced MRI (DCE-MRI) is crucial for assessing myocardial perfusion.
- Understanding water and contrast agent (CR) exchange kinetics is vital for accurate interpretation.
- Previous models often assumed infinitely fast or slow water exchange, potentially oversimplifying cardiac perfusion.
Purpose of the Study:
- To investigate the shutter-speed pharmacokinetic effects on transendothelial and transcytolemmal water exchange in human myocardium using DCE-MRI.
- To determine the influence of various kinetic parameters on the analysis of noisy cardiac perfusion data.
- To evaluate the relationship between contrast reagent permeability-surface area product (P(CR)S) and blood flow under resting and hyperemic conditions.
Main Methods:
- Acquisition of human myocardial (1)H(2)O T(1)-weighted dynamic contrast-enhanced MRI data during first-pass of a low gadolinium diethylenetriaminepenta-acetate (GdDTPA(2-)) dose.
- Analysis of pharmacokinetic effects, including pseudo-first-order rate constant (K(trans)) for CR transfer and water molecule lifetimes (tau(i), tau(b)).
- Estimation of P(CR)S by combining K(trans) with independently determined flow (F) values; comparison of resting and adenosine-induced hyperemic states.
Main Results:
- Water exchange kinetics in the myocardium are not infinitely fast or slow, even with short acquisition windows and high K(trans).
- Intracellular (tau(i)) and intravascular (tau(b)) water lifetimes are not the most influential parameters in noisy cardiac perfusion data.
- P(CR)S values closely match K(trans) in resting myocardium, indicating permeation-limited GdDTPA(2-) extravasation.
- P(CR)S increases with flow during hyperemia, primarily due to capillary recruitment (increase in S).
- Capillary blood volume fraction (v(b)) is sensitive in the analysis and increases with flow, also showing a component due to capillary recruitment.
Conclusions:
- The gadolinium diethylenetriaminepenta-acetate (GdDTPA(2-)) extravasation in resting human myocardium is permeation-limited, validating K(trans) and P(CR)S estimations.
- P(CR)S is not constant with changing flow and increases during hyperemia due to capillary recruitment.
- Capillary recruitment significantly influences both P(CR)S and capillary blood volume fraction (v(b)) during increased myocardial blood flow.
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