Myocardial strain in sub-acute peri-infarct myocardium.
OBJECTIVE
In the absence of additional ischemic insults, the peri-infarct region surrounding the infarct myocardium can recover function. T2 weighted MRI signal is sensitive to edema and used to detect peri-infarct, salvageable myocardium. The main purpose of this study was to investigate the alterations in myocardial strain in the peri-infarct myocardium as compared to normal and infarct myocardium.


METHODS
Comprehensive MRI of the myocardium was performed in five pigs 6-7 days following coronary artery occlusion-reperfusion myocardial injury. MRI included tagged cine images for myocardial strain, T2weighted (T2w)-images and late gadolinium enhancement (LGE) for assessing myocardial viability. Automated signal intensity thresholds were used to define tissue edema and myocardial infarct. Maximum-shortening strains were analyzed in the infarct, peri-infarct and normal myocardial sectors. The results were correlated with triphenyltetrazolium-chloride (TTC) and hemotoxylin-eosin stained tissue images.


RESULTS
We found an excellent correlation of LGE with TTC (r = 0.94, P < 0.05). T2w-images markedly overestimated the infarct size (25 +/- 3%). Both the healthy and peri-infarct myocardial sectors had higher myocardial strain than infarct myocardial sectors (P < 0.05). Clear demarcation between infarct and non-infarct myocardium was noted on histology.


CONCLUSIONS
Peri-infarct myocardium continues to demonstrate T2 signal enhancement to at least 7 days, but this region has preserved mechanical function. T2-weighted imaging and myocardial strain measurements provide complementary information and both may be useful for characterization of the peri-infarct myocardium.
Department of Biochemistry and Molecular Genetics, University of Alabama, Birmingham, AL, USA.
Balázs
B
Ruzsics
Pál
P
Surányi
Pál
P
Kiss
Brigitta C
BC
Brott
Silvio
S
Litovsky
Thomas S
TS
Denney
Inmaculada
I
Aban
Steven G
SG
Lloyd
Tamas
T
Simor
Gabriel A
GA
Elgavish
Himanshu
H
Gupta
D000818:Animals; D003287:Contrast Media / Q000008:administration & dosage; D019786:Gadolinium DTPA / Q000008:administration & dosage; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods*; D009203:Myocardial Infarction / Q000503:physiopathology*; D009206:Myocardium / Q000473:pathology; D013552:Swine
D003287:Contrast Media; D019786:Gadolinium DTPA