Absolute myocardial perfusion in canines measured by using dual-bolus first-pass MR imaging.
OBJECTIVE
To compare fluorescent microsphere measurements of myocardial blood flow (MBF) with qualitative, semiquantitative, and fully quantitative measurements of first-pass perfusion at magnetic resonance (MR) imaging.


METHODS
Coronary artery occlusion or intracoronary adenosine infusion was successfully performed in 16 beagles; both procedures were performed simultaneously in one animal. MBF was assessed at microsphere analysis. First-pass myocardial perfusion MR imaging was performed during a dual-bolus administration of gadopentetate dimeglumine (0.0025 mmol/kg followed by 0.10 mmol/kg). The absolute myocardial perfusion at MR imaging was calculated by using Fermi function deconvolution methods. Qualitative, semiquantitative, and absolute myocardial perfusion MR imaging measurements were compared with microsphere MBF measurements by using paired t tests, linear correlation, and Bland-Altman analysis.


RESULTS
Fully quantitative (ie, absolute) analysis of MBF at MR imaging correlated with microsphere MBF measurement (r = 0.95, P <.001) across the full range of blood flow rates encountered (from 0 to >5.0 mL/min/g). Similar close correlations were observed in endocardial and epicardial segments (representing approximately 0.85 g of the myocardium). With modest increases in MBF, qualitative measurements plateaued in the hyperemic zones. Semiquantitative measurements did not correlate with MBF as well (r = 0.69-0.89); they plateaued around 3.0 mL/min/g.


CONCLUSIONS
Dual-bolus MR imaging enabled accurate measurement of absolute epicardial and endocardial perfusion across a wide range of blood flow rates (0 to >5.0 mL/min/g). Use of qualitative MR imaging measures such as the contrast enhancement ratio led to substantially underestimated hyperemic blood flow measurements.
Christian
Timothy F
TF
Laboratory of Cardiac Energetics, National Heart, Lung and Blood Institute, National Institutes of Health, Department of Health and Human Services, Bldg 10, Rm B1D416, MSC 1061, 10 Center Dr, Bethesda, MD 20892-1061, USA.
Rettmann
Dan W
DW
Aletras
Anthony H
AH
Liao
Steve L
SL
Taylor
Joni L
JL
Balaban
Robert S
RS
Arai
Andrew E
AE
D000818:Animals; D003287:Contrast Media; D003326:Coronary Circulation; D004285:Dogs; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008863:Microspheres
D003287:Contrast Media