Coronary plaque imaging with MSCT

A series of articles in different journals in the past few months have added fuel to the possible role of multi-slice CT in the diagnosis and follow-up of coronary artery plaques.

The first is an article by Leber AW et al in the Journal of the American College of Cardiology (JACC), where the authors compared 16-slice CT with intravascular ultrasound. Their conclusion was: "this study demonstrates that, in the case of diagnostic image quality, contrast-enhanced MDCT permits an accurate identification of coronary plaques and that computed tomography density values measured within plaques reflect echogenity and plaque composition."

This week there is an article in Circulation by Jensen LO et al that shows that simvastatin over 12 months is associated with significant reduction in the plaque plus media volumes as well as the external elastic membrane volumes in coronary arteries. They studied 40 males with hypercholesterolemia with state-of-the-art intravascular ultrasound of the coronary arteries, at baseline, 3 months after a lipid-lowering diet and 12 months after simvastatin. Similar studies have already shown reduction in plaque in the aorta and carotid arteries with various types of statins.

Another article this week in JAMA by Wiegman A et al shows that in patients with familial hypercholesterolemia, the use of pravastatin shows definite regression of the carotid intima-media thickness as measured by ultrasound.

IVUS is an invasive technique that cannot be used routinely in clinical practice to diagnose plaque and to monitor it. Coronary artery CT can be used for this purpose since it is relatively non-invasive and simple to perform. If coronary CT is equivalent to IVUS, then CT will also be able to do both; diagnose plaques as well as show regression on treatment. This may become more and more important as statins become over-the-counter (OTC) drugs, as has just happened in the UK.

Not only that, the associated use of calcium scoring also helps. Calcium scoring has already has become a routine affair and Achenbach et al have even shown reduction of the total calcium burden with the use of statins.

In addition to showing stenoses, if coronary CT can help in the diagnosis and management of non-stenosing atherosclerotic disease and show eventually reduced cardiac events and mortality in the general population, it will become a tremendously important modality in cardiac practice.