Acute myocardial ischemia detected in vivo by computed tomography

Normal and acutely ischemic myocardium was imaged by dynamic computed transmission tomography (CT) in dogs during injection of contrast material. The rotary fan-beam CT scanner used could obtain 16 sequential, ungated, 3.0-second scans at 13-20-second intervals. Time-attenuation curves of myocardial enhancement, which were constructed from serial CT images of normally functioning anterior and lateral left ventricular myocardium, demonstrated mean +/- SEM baseline values: 37 +/- 3.3 and 32 +/- 4.0 CT#s; mean +/- SEM peak enhancement: 72 +/- 4.1 and 73 +/- 3.9 CT#s; and decay in enhancement having mean +/- SD time constants: 3.12 +/- 0.27 and 3.17 +/- 0.22 minutes. Regions of acutely ischemic myocardium demonstrated lower but not significantly different baseline values (mean +/- SEM = 25 +/- 4.3 CT#s) from normal (mean +/- sEM = 37 +/- 3.3 CT#s), without a peak and decay in enhancement. The authors conclude that regions of experimentally-produced acute ischemia are readily detected in vivo by dynamic CT imaging as absent or markedly reduced myocardial contrast enhancement.