Coronary Artery Disease (Case #1)

Figure 1

History: 52-year-old asymptomatic male smoker with mildly elevated cholesterol and family history of coronary artery disease, volunteered for CT coronary angiography at Main Street Radiology.

Technique: Oral beta-blocker was administered the night prior to the exam to reduce the heart rate below 70 bpm. 100 cc of intravenous contrast was administered during a 20 second breath-hold. EKG-gated images were obtained on a 16-detector spiral CT.

Figure 2

Findings: 3D anterior image of heart (figure 1) outlines normal anatomy (AO = aorta; PA = pulmonary artery; RA = right atrium; RCA = right coronary artery; LAD = left anterior descending artery; RV = right ventricle; LV = left ventricle; DX = diagonal branch). 3D oblique image of the left coronary arteries (figure 2) demonstrates no significant stenosis (LCX = left circumflex artery; RI = ramus intermedius). 3D oblique image of the RCA demonstrates focal stenosis proximally (arrow). A non-calcified (soft) plaque (arrow) is seen on the 2D axial-oblique image of the right coronary artery (figure 4), with approximately 40% stenosis.

Recommendations: Aggressive intervention to reduce risk factors.

Figure 3

Discussion: In October 2003, MSR installed the first 16-detector spiral CT in Queens. With this new technology, we are one of the first facilities in the New York area to perform many sophisticated studies including CT coronary angiography.

The 16-detector CT enables "isotropic" volume acquisition, where true 3D images can be obtained in every projection. Previously available CT technology suffered from loss in resolution when images were viewed at different angles. Coronary arteries can now be viewed at the highest resolution, not dependent on its orientation. In addition, due to its unprecedented speed, the 16 detector CT can effectively "freeze" cardiac motion for heart rates less than 70 bpm.

Early reports indicate that CT coronary angiography may ultimately replace diagnostic cardiac catheterization, with reported sensitivity of 95% (Nieman, Circulation 2002; 106 (16): 2051-4).

Figure 4

Advantages of CT coronary angiography include:

  1. CT angiography is non-invasive, only requiring IV injection of iodinated contrast
  2. Less expensive
  3. Aside from the lumen, the vessel wall and plaque can be imaged and characterized ("soft" vs. "hard" plaque)
  4. 2D and 3D images can be viewed at every angle and in cross section, increasing accuracy of grading of stenosis

As up to 50% of diagnostic cardiac catheterizations fail to show significant disease, CT coronary angiography may take on an important role in screening patients with indications for cardiac catheterization. As more studies are published in the medical literature, indications for CT coronary angiography should be better defined.