Uniformity and repeatability of normal resting myocardial blood flow in rats using [13N]-ammonia and small animal PET.
OBJECTIVE
This study aimed to quantitatively evaluate population variability, regional uniformity and repeatability of myocardial blood flow measurements using [13N]-ammonia and small animal PET.


METHODS
Serial PET scans were conducted on Sprague-Dawley rats using [13N]-ammonia to study relative perfusion and absolute myocardial blood flow (ml/min/g). FlowQuant automated analysis software was used to produce five-segment polar maps to investigate regional myocardial blood flow differences. The interobserver and intraobserver repeatability was assessed quantitatively using Bland-Altman analysis.


RESULTS
Absolute myocardial blood flow values were 4.3 ± 1.1 ml/min/g, corresponding to a population variability of 25.5%. There were significant age-related increases in resting myocardial blood flow (r2=0.59, P<0.001). The test-retest differences had a coefficient of repeatability of 24.5% of the mean myocardial blood flow. The operator variability was small, relative to the population variability.


CONCLUSIONS
Repeatable myocardial blood flow values are minimally influenced by operator intervention. However, age-related myocardial blood flow increases must be taken into account when comparing measurements between experimental groups.
National Cardiac PET Centre, University of Ottawa Heart Institute, Ottawa, Ontario, Canada.
Marc
M
Lamoureux
Stephanie
S
Thorn
Tyler
T
Dumouchel
Jennifer M
JM
Renaud
Ran
R
Klein
Samantha
S
Mason
Mireille
M
Lortie
Jean N
JN
DaSilva
Rob S
RS
Beanlands
Robert A
RA
deKemp
D000641:Ammonia; D000818:Animals; D049628:Body Size; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D008297:Male; D009590:Nitrogen Radioisotopes; D015588:Observer Variation; D049268:Positron-Emission Tomography / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012146:Rest
D009590:Nitrogen Radioisotopes; D000641:Ammonia