Quantification of regional myocardial blood flow in a canine model of stunned and infarcted myocardium: comparison of rubidium-82 positron emission tomography with microspheres.
BACKGROUND
Myocardial viability and quantification of regional myocardial blood flow (MBF) are important for the diagnosis of heart disease. Positron emission tomography is the current gold standard for determining myocardial viability, but most positron-emitting perfusion tracers require an on-site cyclotron. Rubidium-82 ((82)Rb) is a myocardial perfusion tracer that is produced using an on-site generator. This study investigates (82)Rb-measured MBF in canine models of stunned and infarcted myocardium compared with selected measurements obtained concurrently using microspheres.


METHODS
Myocardial stunning and infarction were created in canines by occluding the left anterior descending for 15 min and 2 h, respectively. Stunning was produced in all animals; six animals were reperfused after the 2 h occlusion, whereas the other six animals remained occluded permanently. Regional MBF was measured in each group during rest and dobutamine stress at acute and chronic (8 weeks postinsult) time points using dynamic (82)Rb perfusion imaging and radioactively labeled microspheres.


RESULTS
Average resting MBF with microspheres and Rb was 0.68+/-0.02 versus 0.73+/-0.01 (P<0.001) in nonischemic tissue, and 0.53+/-0.03 versus 0.42+/-0.02 (P<0.001) in the region-at-risk tissue, respectively. Average MBF during stress with microspheres and Rb was 2.78+/-0.15 versus 3.53+/-0.16 (P<0.05) in the nonischemic tissue, and 1.90+/-0.20 versus 2.31+/-0.26 (P = NS) in the region-at-risk tissue, respectively.


CONCLUSIONS
Despite the small significant differences, the dynamic (82)Rb measurements provide estimates of MBF in stunned and acutely and chronically infarcted tissue at rest and during hyperemia that correspond with clinical interpretation.
Lekx
Katie S
KS
Imaging Program, Lawson Health Research Institute and Nuclear Medicine Department, St. Joseph's Health Care, London, Canada.
deKemp
Robert A
RA
Beanlands
Robert S B
RS
Wisenberg
Gerald
G
Wells
R Glenn
RG
Stodilka
Robert Z
RZ
Lortie
Mireille
M
Klein
Ran
R
Zabel
Pamela
P
Kovacs
Michael S
MS
Sykes
Jane
J
Prato
Frank S
FS
D000818:Animals; D003326:Coronary Circulation; D004195:Disease Models, Animal; D004285:Dogs; D006321:Heart / Q000000981:diagnostic imaging / Q000503:physiopathology; D006940:Hyperemia / Q000000981:diagnostic imaging / Q000503:physiopathology; D008863:Microspheres; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D017682:Myocardial Stunning / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D049268:Positron-Emission Tomography; D012146:Rest; D012414:Rubidium Radioisotopes
D012414:Rubidium Radioisotopes