Characterization of cryoinjury-induced infarction with manganese-and gadolinium-enhanced MRI and optical spectroscopy in pig hearts.
OBJECTIVE
To investigate progression of cryoinjury in pigs using contrast-enhanced magnetic resonance imaging (MRI) as well as optical spectroscopy and imaging.


METHODS
Cryoinjury was produced in 16 pigs in vivo and investigated using Gd-and Mn-enhanced MRI, optical imaging/spectroscopy and histology in acute and chronic setting up to 4 weeks after the injury.


RESULTS
(1) Acute cryoinjury resulted in formation of a lesion with a severely reduced rate of sub-epicardial indocyanine green (intravascular optical flow tracer) passage. In vivo late Gd-enhanced MRI showed a approximately 10 mm deep hypointense area that was surrounded by a hyperintense rim while ex vivo Mn-enhanced MRI (MEMRI) detected a homogenous hypointense zone. Histological and spectroscopic examination revealed embolic erythrocytes blockages within the cryolesion with a thin necrotic rim neighboring the normal myocardium. (2) Chronic 4-week cryoinjury was characterized by uniform Gd-enhancement, whereas MEMRI revealed reduced Mn(2+)enhancement. Histological examination showed replacement of the cryoinjured myocardium by scar tissue.


CONCLUSIONS
Acute cryoinjury resulted in formation of a no-reflow core embolized by erythrocytes and surrounded by a rim of necrotic tissue. Upon injury progression, the no-reflow zone shrunk and was completely replaced with scar tissue by 4 weeks after injury.
Yang
Yanmin
Y
Department of Biochemistry and Medical Genetics, Faculty of Medicine, University of Manitoba, Winnipeg, MB, Canada.
Sun
Jiankang
J
Gervai
Patricia
P
Gruwel
Marco L
ML
Jilkina
Olga
O
Gussakovsky
Eugene
E
Yang
Xi
X
Kupriyanov
Valery
V
D000818:Animals; D003287:Contrast Media; D005682:Gadolinium; D007036:Hypothermia, Induced; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008345:Manganese; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000209:etiology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013057:Spectrum Analysis / Q000379:methods*; D013552:Swine
D003287:Contrast Media; D008345:Manganese; D005682:Gadolinium