Perfusion weighted color maps for enhanced visualization of myocardial infarction by MSCT: preliminary experience

The reliable detection of myocardial perfusion defects and myocardial infarction (MI) is of great interest in the comprehensive workup of coronary artery disease. The aim of this study was to optimize the ability of contrast-enhanced cardiac multislice spiral computed tomography (MSCT) for detecting hypoperfused myocardium as surrogate marker of MI using a newly developed post-processing technique.

First a model-based software tool for semi-automated detection of the long axis of the left ventricle and assignment of left-ventricular segments was developed using a region growing algorithm and a point distribution model. To visualize changes of the myocardial contrast enhancement pattern color coding was performed after spreading of the attenuation values. 15 patients (12 men, mean age 57 +/- 15 years) with a history of MI underwent cardiac MSCT (16 x 0.75 mm, 120 kV, 550 mA s(eff.), 100 ml Iopromide) and contrast enhanced delayed enhanced magnetic resonance imaging (DE-MRI) after administration of 0.2 mmol Gd-DTPA/kg/bodyweight as reference standard. Presence of infarction was assessed from MSCT, post-processed MSCT images and DE-MRI using a 17-segment model of the left ventricle.

On DE-MRI MI was present in 78/255 myocardial segments. From conventional MSCT images MI was detected in 63/255 segments (5 false positive; sensitivity 74.4%; specificity: 97.1%), while on post-processed images MI was assigned to 74/255 segments (6 false positive; sensitivity 87.2%; specificity: 96.6%). Agreement between DE-MRI and conventional MSCT images for detecting MI was kappa = 0.756. Using post-processed images agreement improved to kappa = 0.850.

MSCT detection of hypoperfused myocardium as surrogate for MI can be improved using dedicated post processing algorithms.