Myocardial Blood Volume Is Associated With Myocardial Oxygen ConsumptionAn Experimental Study With Cardiac Magnetic Resonance in a Canine Model
Kyle S. McCommis, BS*,
Haosen Zhang, PhD*,
Thomas A. Goldstein, MS*,
Bernd Misselwitz, PhD ,
Dana R. Abendschein, PhD ,
Robert J. Gropler, MD*,
Jie Zheng, PhD*,*
* Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri
Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri
Bayer Schering Pharma AG, Berlin, Germany
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Figure 1 Imaging Study Protocol
The blood oxygen level-dependent (BOLD) method was used to evaluate the myocardial oxygen extraction fraction, and first-pass perfusion was used to evaluate both myocardial blood flow and volume. The BOLD and first-pass perfusion scans were performed at rest and during either intravenous dipyridamole or dobutamine hyperemia. The numbers below the line represent the approximate time in minutes between events.
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Figure 2 Representative Short-Axis Maps From a Dog With a 96% LAD Stenosis During Dipyridamole
The myocardial blood flow map (A) and myocardial blood volume map (B), derived from the first-pass perfusion images, clearly show an anterior perfusion defect. The extraction fraction map (C), derived from the blood oxygen level-dependent T2-weighted images, shows greater extraction fraction in the stenotic anterior region as the result of the decreased oxygen supply. The stenotic LAD region is marked with a yellow region of interest. The myocardial blood flow scale units are ml/min/g (A); myocardial blood volume scale units are ml/g (B). LAD = left anterior descending; LV = left ventricle.
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Figure 3 Regression Analysis to Discern Relationships Among MBF, MBV, and MVO2 Reserve During Dipyridamole or Dobutamine
(A) Control dogs show only mild and moderate correlation between MBV reserve and MVO2 reserve during dipyridamole (DIP) (pink circles) and dobutamine (DOB) (green circles), respectively. (B) In stenotic regions, MBF reserve is slightly more correlated with MVO2 reserve during DIP (pink circles). (C) However, MBV reserve is more correlated with MVO2 reserve during DOB (green circles). This finding supports the theory that MBV is required during inotropic stimulation when MVO2 is more significantly increased. MBF = myocardial blood flow; MBV = myocardial blood volume; MVO2 = myocardial oxygen consumption.
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