Accuracy of Cardiac Magnetic Resonance of Absolute Myocardial Blood Flow With a High-Field SystemComparison With Conventional Field Strength
Timothy F. Christian, MD*,*,
Stephen P. Bell, BS*,
Lawrence Whitesell, BS ,
Michael Jerosch-Herold, PhD
* University of Vermont College of Medicine, Burlington, Vermont
University of Wisconsin College of Medicine, Madison, Wisconsin
Brigham and Women's Hospital, Department of Radiology, Harvard University, Boston, Massachusetts
* Reprint requests and correspondence: Dr. Timothy F. Christian, Professor of Medicine, Director of Cardiac Imaging, MCHV McClure 1060, University of Vermont, Burlington, Vermont 05495 (Email: timothy.christian{at}uvm.edu).
Objectives: The aim of this study was to determine the accuracy of cardiac magnetic resonance (CMR) first pass (FP) perfusion measures of absolute myocardial blood flow (MBF) with a 3.0-T magnet and compare these measures with FP perfusion at 1.5-T with absolute MBF by labeled microspheres as the gold standard.
Background: First-pass magnetic resonance (MR) myocardial perfusion imaging can quantify MBF, but images are of low signal at conventional magnetic field strength due to the need for rapid acquisition.
Methods: A pig model was used to alter MBF in a coronary artery during FP CMR (intracoronary adenosine followed by ischemia). This produces an active zone with a range of MBF and a control zone. Microspheres were injected into the left atrium with concurrent reference sampling. FP MR perfusion imaging was performed at 1.5-T (n = 9) or 3.0-T (n = 8) with a saturation-recovery gradient echo sequence in short-axis slices during a bolus injection of 0.025 mmol/kg gadolinium–diethylenetriamine pentaacetic acid. Fermi function deconvolution was performed on active and control region of interest from short-axis slices with an arterial input function derived from the left ventricular cavity. These MR values of MBF were matched to microsphere values obtained from short-axis slices at pathology.
Results: Occlusion MBF was 0.21 ± 0.26 ml/min/g, adenosine MBF was 2.28 ± 0.99 ml/min/g, and control zone MBF was 0.70 ± 0.22 ml/min/g. The correlation of MR FP CMR with microsphere was close for both field strengths: 3.0-T, r = 0.98, p < 0.0001 and 1.5-T, r = 0.95, p < 0.0001. The 95% confidence limits of agreement were slightly narrower at 3.0-T (3.0-T = 0.49 ml/min/g, 1.5-T = 0.68 ml/min/g, p < 0.05). The FP CMR image characteristics were better at 3.0-T (noise and contrast enhancement were both superior at 3.0-T). In myocardial zones where MBF <0.50 ml/min/g, the correlation with microspheres was closer at 3.0-T (r = 0.55 at 1.5-T, r = 0.85 at 3.0-T).
Conclusions: Absolute MBF by FP perfusion imaging is accurate at both 1.5- and 3.0-T. Signal quality is better at 3.0-T, which might confer a benefit for estimating MBF in ischemic zones.
Key Words: cardiac imaging • CMR • coronary flow reserve • ischemia • myocardial perfusion
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Abbreviations and Acronyms
| | Bo = magnetic field strength | | CMR = cardiac magnetic resonance | | CNR = contrast-to-noise ratio | | DTPA = diethylenetriamine pentaacetic acid | | FP = first pass | | Gd = gadolinium | | LAD = left anterior descending coronary artery | | MBF = myocardial blood flow | | MR = magnetic resonance | | RF = radiofrequency | | SI = signal intensity | | SNR = signal-to-noise ratio | | TIC = time intensity curve |
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