Myocardial perfusion imaging based on the blood oxygen level-dependent effect using T2-prepared steady-state free-precession magnetic resonance imaging.
BACKGROUND
The decision to perform coronary revascularization procedures may hinge on assessment of myocardial perfusion reserve. Blood oxygen level-dependent (BOLD) MRI is a potential method to detect the effects of regional variations in myocardial blood flow during vasodilation.


RESULTS
We imaged dogs (n=13) on a 1.5-T whole-body MRI scanner using a new T(2)-prepared steady-state free-precession (SSFP) MRI pulse sequence sensitive to BOLD contrast. Images (in-plane resolution approximately 1 mm(2)) of 5 short-axis and 2 long-axis slices of the heart were acquired during graded levels of adenosine infusion via a surgically placed left circumflex (LCx) catheter (n=11) or via a right atrial catheter in animals with an LCx occluder (n=2). Relative myocardial perfusion was measured with the use of fluorescent microspheres. Signal intensity changes in myocardium subtended by the left anterior descending coronary artery were compared with those in the LCx region. Unprocessed T(2)-weighted images revealed changes in signal intensity corresponding to areas of regional vasodilation or reduced myocardial perfusion reserve during systemic vasodilation. At maximal vasodilation, the signal intensity ratio in the LCx versus left anterior descending territories increased by 33+/-4% compared with baseline, corresponding to a 3.8+/-0.3-fold increase in relative perfusion (P<0.01). MR intensity at progressive levels of vasodilation demonstrated good agreement with microsphere flow (R=0.80, P<0.01).


CONCLUSIONS
T(2)-prepared SSFP BOLD imaging is a promising method to determine an index of myocardial perfusion reserve in this animal model.
Fieno
David S
DS
Department of Radiology, Feinberg Cardiovascular Research Institute, Northwestern University, Chicago, Ill., USA.
Shea
Steven M
SM
Li
Yongzhong
Y
Harris
Kathleen R
KR
Finn
J Paul
JP
Li
Debiao
D
D000241:Adenosine / Q000494:pharmacology; D000818:Animals; D006328:Cardiac Catheterization; D003326:Coronary Circulation; D004285:Dogs; D005240:Feasibility Studies; D005456:Fluorescent Dyes; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008863:Microspheres; D009206:Myocardium / Q000473:pathology*; D010100:Oxygen / Q000097:blood; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology
D005456:Fluorescent Dyes; D014665:Vasodilator Agents; D000241:Adenosine; D010100:Oxygen