Purpose: To systematically evaluate the diagnostic accuracy of contrast-enhanced multidetector-row CT (MDCT) in assessing the presence, age and size of myocardial infarctions.
Methods and Materials: 106 patients underwent contrast-enhanced four-detector-row CT of the heart. In all patients, left heart catheterization with biplane cineventriculography was available for comparison. MDCT images were reviewed for the presence of myocardial infarctions. Infarct areas were detected as regions of reduced uptake of contrast in the early arterial phase. Hounsfield Units (HU) were measured for infarcted areas and for areas of normal myocardium. Myocardial wall thickness was measured and infarctions were divided into aneurysmatic and non-aneurysmatic infarctions. Additionally, a volumetric assessment of the infarct size was performed. In cineventriculography, presence of infarction was determined by analysis of global left ventricular function (ejection fraction, EF) and regional wall motion analysis.
Results: In 27 of 106 patients, myocardial infarctions were detected according to cineventriculography. 14 were acute/subacute infarctions (mean age 5 days) and 13 were chronic infarctions (mean age 729 days). MDCT made a correct diagnosis in 24 cases, with 3 false-negative and 5 false-positive results (sensitivity 89%, specificity 94%, accuracy 92%). Comparing the density (HU) of infarcted vs non-infarcted myocardium, the mean HU of infarcted areas was 48 ± 10 HU vs 114 ± 18 HU for non-infarcted myocardium (p<0,01). MDCT was able to reliably differentiate between acute/subacute and chronic infarctions according to certain morphologic criteria. Comparing aneurysmatic to non-aneurysmatic infarctions in MDCT, there was a significantly lower ejection fraction for myocardial infarctions with aneurysms (EF 40,2 ± 11,5 vs 58,5 ± 8,6, p < 0,01). The infarct volumes of non-aneurysmatic infarctions (5,9 ± 3,6 cm3) showed a strong negative correlation to EF according to cineventriculography, i.e., the larger the infarct volumes measured in MDCT, the worse was the EF (r = - 0,90, p<0,01). In all 24 infarctions detected correctly, there was a complete agreement of infarct localization in MDCT as compared to regional wall motion abnormality in cineventriculography.
Conclusion: Contrast-enhanced MDCT is a sensitive tool for the detection of myocardial infarctions. MDCT can discern between acute/subacute and chronic infarctions. Infarct volume and localization can be assessed accurately as compared to cineventriculography.
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