Improved detection of subendocardial hyperenhancement in myocardial infarction using dark blood-pool delayed enhancement MRI.
OBJECTIVE
Delayed enhancement MRI using fast segmented k-space inversion recovery (IR) gradient-echo imaging is a well established "bright-blood" technique for identifying myocardial infarction and is used as the reference standard sequence in this study. The purpose of this study was to validate a recently developed dark blood-pool delayed enhancement technique in a porcine animal model, evaluate its performance in human patients, and quantify its performance compared with the reference standard in both.


METHODS
In an animal study, the reference standard and dark blood-pool delayed enhancement were assessed in three pigs with induced myocardial infarction. In a human study, 26 patients, 31-81 years old (19 men and seven women), with a known history of myocardial infarction were imaged using the reference standard and dark blood-pool delayed enhancement. Contrast-to-noise ratio (CNR), signal intensity ratio, signal-to-noise ratio (SNR), and qualitative scores of hyperenhancement were recorded. Measurements were compared using paired samples t test and Wilcoxon's signed rank test.


RESULTS
In the animal study, the mean CNR of infarct to blood pool was 11 times higher for dark blood-pool delayed enhancement than for the reference standard. The mean SNR was 4.4 times higher for the reference standard. In the human study, the mean CNR and signal intensity ratio of hyperenhancing myocardium to the blood pool were 1.9 (p = 0.04) and 5.5 (p < 0.01) times higher, respectively, for dark blood-pool delayed enhancement compared with reference standard. The mean CNR and signal intensity ratio of hyperenhancing myocardium to normal myocardium and SNR were 2.8 (p < 0.01), 1.3 (p = 0.07), and 2.8 (p < 0.01) higher, respectively, for the reference standard. Qualitative analysis identified seven extra segments with grade 1 scars using dark blood-pool delayed enhancement (p < 0.01).


CONCLUSIONS
Dark blood-pool delayed enhancement is complementary to the reference standard. It can detect more subendocardial foci of hyperenhancement, thus potentially identifying more infarcts and changing patient management.
Department of Radiology, Cardiovascular Imaging Section, Northwestern University, 737 N Michigan Ave., Ste. 1600, Chicago, IL 60611, USA. farrellycormac@gmail.com
Cormac
C
Farrelly
Wolfgang
W
Rehwald
Michael
M
Salerno
Amir
A
Davarpanah
Aoife N
AN
Keeling
Jason T
JT
Jacobson
James C
JC
Carr
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D004699:Endocardium / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D009206:Myocardium / Q000473:pathology*; D013552:Swine