Chronic myocardial infarction detection and characterization during coronary artery calcium scoring acquisitions

Background

Hypoenhanced regions on multidetector CT (MDCT) coronary angiography correlate with myocardial hyperperfusion. In addition to a limited capillary density, chronic myocardial infarction (MI) commonly contains a considerable amount of adipose tissue.

Objective

We explored whether regional myocardial hypoenhancement on contrast-enhanced MDCT could be identified with standard coronary artery calcium (CAC) scoring acquisitions with noncontrast CT.

Methods

Consecutive patients with a history of MI who were referred for contrast-enhanced MDCT from November 2006 until March 2009 were studied. Noncontrast CT for CAC scoring was also performed. The correlation between regional myocardial hypoenhancement on contrast-enhanced CT and regional myocardial hypoattenuated areas on noncontrast CT was defined.

Results

Eighty-three patients (mean age, 61.5±12.5 years; n=67; 81% male) with previous MI were studied. A total of 1411 myocardial segments were evaluated. Two hundred thirty-nine segments (17%) showed myocardial hypoenhancement by MDCT and 140 segments (9.6%) by CAC. On a patient level, noncontrast CT showed a sensitivity, specificity, positive predictive value, (PPV) and negative predictive value (NPV) of 66% (95% CI, 0.53–0.77), 100% (95% CI, 0.76–1.00), 100% (95% CI, 0.90–1.00), and 41% (95% CI, 0.26–0.58), respectively, to detect myocardial hypoenhancement. On a per segment level, noncontrast CT showed a sensitivity, specificity, PPV, and NPV of 58% (95% CI, 0.51–0.64), 100% (95% CI, 0.99–1.00), 99% (95% CI, 0.94–1.00), and 92% (95% CI, 0.90–0.93), respectively, to detect myocardial hypoenhancement.

Conclusions

Our findings suggest that chronic MI can be detected with standard CAC scoring acquisitions.

Keywords: Computed tomography, Infarct extension, Necrosis, Perfusion defect