Myocardial ischemia 2

Findings

59-year-old male with history of stable chest pain.

Spectral iodine density and Z effective images unmask myocardial perfusion defect in patient with coronary artery disease.

Short axis conventional and short axis spectral iodine density and Z effective multiplanar reformations (MPR), invasive coronary angiogram

Conventional image shows relatively uniform density of the myocardium, although there are subtle differences in HU values. Spectral iodine density and Z effective images, however, clearly unmask a large perfusion defect in the antero- and inferoseptal regions. Invasive coronary angiography with fractional flow reserve (FFR) measurement confirms presence of significant coronary stenosis in the left anterior descending coronary artery which supplies the hypoperfused region of the septum.

Discussion

Spectral CT allows for evaluation of the significance of coronary artery stenosis by enabling quantitative assessment of myocardial iodine distribution. This may aid in the selection of patients for percutaneous coronary angioplasty.

Short axis MPR of conventional CT image: Shows near homogeneous enhancement of the LV myocardium, although there are subtle differences in HU values of the different regions of interest.

Spectral iodine density map in the short axis orientation: Clearly shows a large perfusion defect with very low iodine concentration (0.2 mg/mL, red arrow) compared to normally enhancing remote areas of the myocardium (between 1.0-1.8 mg/mL iodine uptake).

Spectral Z effective map in the short axis orientation: Confirms low iodine concentration. The effective atomic number of the perfusion defect is close to water (7.3), whereas normally enhancing remote areas of the myocardium have an effective atomic number of close to 8.0 because of iodine uptake.

Invasive coronary angiography: Confirms the presence of significant LAD stenosis. The FFR value was 0.7 (normal: > 0.8).

History

Benefits or pitfalls of dual-energy CT

Key images

Findings