Contrast-enhanced multidetector computed tomography viability imaging after myocardial infarction: characterization of myocyte death, microvascular obstruction, and chronic scar.
BACKGROUND
The ability to distinguish dysfunctional but viable myocardium from nonviable tissue has important prognostic implications after myocardial infarction. The purpose of this study was to validate the accuracy of contrast-enhanced multidetector computed tomography (MDCT) for quantifying myocardial necrosis, microvascular obstruction, and chronic scar after occlusion/reperfusion myocardial infarction.


RESULTS
Ten dogs and 7 pigs underwent balloon occlusion of the left anterior descending coronary artery (LAD) followed by reperfusion. Contrast-enhanced (Visipaque, 150 mL, 325 mg/mL) MDCT (0.5 mm x 32 slice) was performed before occlusion and 90 minutes (canine) or 8 weeks (porcine) after reperfusion. MDCT images were analyzed to define infarct size/extent and microvascular obstruction and compared with postmortem myocardial staining (triphenyltetrazolium chloride) and microsphere blood flow measurements. Acute and chronic infarcts by MDCT were characterized by hyperenhancement, whereas regions of microvascular obstruction were characterized by hypoenhancement. MDCT infarct volume compared well with triphenyltetrazolium chloride staining (acute infarcts 21.1+/-7.2% versus 20.4+/-7.4%, mean difference 0.7%; chronic infarcts 4.15+/-1.93% versus 4.92+/-2.06%, mean difference -0.76%) and accurately reflected morphology and the transmural extent of injury in all animals. Peak hyperenhancement of infarcted regions occurred approximately 5 minutes after contrast injection. MDCT-derived regions of microvascular obstruction were also identified accurately in acute studies and correlated with reduced flow regions as measured by microsphere blood flow.


CONCLUSIONS
The spatial extent of acute and healed myocardial infarction can be determined and quantified accurately with contrast-enhanced MDCT. This feature, combined with existing high-resolution MDCT coronary angiography, may have important implications for the comprehensive assessment of cardiovascular disease.
Lardo
Albert C
AC
Division of Cardiology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA. al@jhmi.edu
Cordeiro
Marco A S
MA
Silva
Caterina
C
Amado
Luciano C
LC
George
Richard T
RT
Saliaris
Anastasios P
AP
Schuleri
Karl H
KH
Fernandes
Veronica R
VR
Zviman
Menekhem
M
Nazarian
Saman
S
Halperin
Henry R
HR
Wu
Katherine C
KC
Hare
Joshua M
JM
Lima
Joao A C
JA
D000208:Acute Disease; D000818:Animals; D016923:Cell Death; D002908:Chronic Disease; D002921:Cicatrix / Q000000981:diagnostic imaging / Q000473:pathology; D003287:Contrast Media; D017023:Coronary Angiography; D003326:Coronary Circulation; D004195:Disease Models, Animal; D004285:Dogs; D008833:Microcirculation; D009203:Myocardial Infarction / Q000000981:diagnostic imaging* / Q000473:pathology*; D032383:Myocytes, Cardiac / Q000473:pathology; D013552:Swine; D015898:Tomography Scanners, X-Ray Computed; D014057:Tomography, X-Ray Computed / Q000295:instrumentation* / Q000379:methods*; D014283:Triiodobenzoic Acids
D003287:Contrast Media; D014283:Triiodobenzoic Acids; C044834:iodixanol