Cardiac MR imaging to measure myocardial blood flow response to the cold pressor test in healthy smokers and nonsmokers.
OBJECTIVE
To determine if myocardial perfusion cardiac magnetic resonance (MR) imaging can show changes in myocardial blood flow (MBF) during the cold pressor test (CPT) and can allow identification of the differing endothelial function of smokers and nonsmokers when compared during adenosine stress.


METHODS
The study was approved by the institutional ethics review board and all participants gave informed written consent. Twenty-nine healthy volunteers (19 nonsmokers, 10 smokers; mean age ± standard deviation, 22 years ± 4) underwent 1.5-T MR imaging and analysis. Myocardial perfusion was assessed during rest, peak CPT, and adenosine hyperemia with a saturation-recovery gradient-echo pulse sequence (spatial resolution, 2.4 × 2.4 × 10 mm). Global, endocardial, and epicardial MBF were calculated by using Fermi-constrained deconvolution. Paired and independent t test statistical analyses were used to compare the responses between tests and groups. Regression analysis was performed to identify predictors of MBF change.


RESULTS
MBF at rest was similar between the nonsmoking and smoking groups (0.97 mL/g/min ± 0.4 vs 0.96 mL/g/min ± 0.3, respectively; P = .96). Nonsmokers responded to CPT with a 47% increase in MBF (1.43 mL/g/min ± 0.5) and smokers responded with a 27% increase (1.22 mL/g/min ± 0.4; P < .001). An endocardial-to-epicardial gradient existed at rest (nonsmokers, 1.10 [P = .002]; smokers, 1.30 [P = .01]) and CPT (nonsmokers, 1.19 [P < .001] smokers, 1.28 [P = .04]) but reversed during adenosine stress (nonsmokers, 0.89 [P = .03]; smokers, 0.92 [P = .42]).


CONCLUSIONS
Myocardial perfusion cardiac MR imaging during CPT can allow assessment of changes in MBF globally and in the separate myocardial layers in healthy smokers and nonsmokers. This allows the combined assessment of endothelium-dependent (CPT) and endothelium-independent (adenosine stress test) MBF reserve in a single study.
From the Multidisciplinary Cardiovascular Research Centre & Leeds Institute of Genetics, Health and Therapeutics (T.A.F., M.M., A.N.M., A.M.L., J.P.G., S.P.), Division of Medical Physics (J.D.B.), and NIHR Leeds Musculoskeletal Biomedical Research Unit and School of Medicine (A.R.), University of Leeds, Leeds, England.
Timothy A
TA
Fairbairn
Manish
M
Motwani
Adam N
AN
Mather
John D
JD
Biglands
Abdulghani M
AM
Larghat
Aleksandra
A
Radjenovic
John P
JP
Greenwood
Sven
S
Plein
D000241:Adenosine / Q000494:pharmacology; D001783:Blood Flow Velocity / Q000502:physiology; D003287:Contrast Media; D003326:Coronary Circulation / Q000502:physiology*; D004730:Endothelium, Vascular / Q000503:physiopathology*; D005080:Exercise Test; D005260:Female; D019786:Gadolinium DTPA; D064368:Healthy Volunteers; D006439:Hemodynamics; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D012907:Smoking / Q000503:physiopathology*; D055815:Young Adult
D003287:Contrast Media; D019786:Gadolinium DTPA; D000241:Adenosine