Effects of time, dose, and inversion time for acute myocardial infarct size measurements based on magnetic resonance imaging-delayed contrast enhancement.
OBJECTIVE
This study sought to investigate the influence of time, dose, and inversion time (TI) and their interactions on myocardial infarct size measurements to establish the foundation for a standardized protocol for multicenter trials.


BACKGROUND
There is growing interest in using magnetic resonance imaging (MRI) infarct size measurements as an end point in clinical trials. However, no standardized protocol exists, and there are limited data concerning the effects of time, contrast agent dose, and TI.


METHODS
First, we determined the influence of postcontrast imaging time (5 to 40 min), contrast agent dose (0.1 vs. 0.2 mmol/kg), TI, and their interactions in an animal model (n = 14). Second, we tested whether the findings of the animal study apply to patients and are generalizable. Therefore, we retested the diagnostic window in a multicenter study. A total of 48 patients with first acute myocardial infarction (AMI) from three centers were imaged twice (5 and 30 min) after injection of 0.15 mmol/kg gadolinium diethylenetriamine-pentaacetate using an adjusted TI.


RESULTS
The animal study showed that the infarct size is independent of time and dose (p = 0.9 and p = 0.16, respectively) using an adjusted TI. Using a fixed TI, however, infarct size is a function of time and dose (p = 0.0001 and p = 0.01, respectively). The multicenter study showed that MRI 1 (16.9 +/- 12% of left ventricle) was not statistically different from MRI 2 (16.4 +/- 12% of left ventricle, p = NS) with no difference between sites (p = NS).


CONCLUSIONS
The AMI size can be measured with MRI using a contrast dose between 0.1 and 0.2 mmol/kg and a time window of 5 to 30 min after contrast administration, provided that the TI is adjusted.
Wagner
Anja
A
Duke Cardiovascular MR Center, Durham, North Carolina 27710, USA.
Mahrholdt
Heiko
H
Thomson
Louise
L
Hager
Stefan
S
Meinhardt
Gabriel
G
Rehwald
Wolfgang
W
Parker
Michele
M
Shah
Dipan
D
Sechtem
Udo
U
Kim
Raymond J
RJ
Judd
Robert M
RM
D000328:Adult; D000368:Aged; D000818:Animals; D002985:Clinical Protocols / Q000592:standards*; D003287:Contrast Media / Q000494:pharmacology; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D011446:Prospective Studies; D018570:Risk Assessment; D013997:Time Factors
D003287:Contrast Media; D019786:Gadolinium DTPA