Coming close on the heels of the article by Leber et al and the accompanying editorial by Rumberger, is another article by van Mieghem et al in JACC, that discusses the role of various imaging modalities in the evaluation of subclinical atherosclerosis.
Apart from MSCT and IVUS, they have used IVUS-based palpography and quantitative echogenecity measurements to evaluate plaque.
Their results were as follows "First, with IVUS as a gold standard, noninvasive MCSTA can identify atherosclerotic plaque, in vessels with only minimal angiographic disease, with high sensitivity and moderate specificity. Second, further investigation of such plaque with novel IVUS-based imaging techniques (palpography and echogenicity) showed that features potentially indicative of vulnerable plaques are both widespread and highly prevalent. Third, although conventional imaging with quantitative coronary angiography and IVUS demonstrates no significant changes in lumen or plaque dimensions, the biomechanical properties of the plaques, assessed by palpography, showed significant changes over a relatively short period. Finally, circulating levels of measured biomarkers showed no significant correlations with focal imaging end points identified by conventional and novel imaging modalities."
In short MSCT had good sensitivity but poor specificity as has been shown by other studies. Palpography showed high strain rates in many plaques even those remote from critical plaques and changes in palpography occurred quickly with aggressive statin therapy.
The same group has also published another article on palpography in Circulation in 2003.
I have emailed the author for permission to use an image from their article - this image shows a single case with comparative images of MSCT, IVUS, palpography and echogenecity evaluation.
As things stand, it is patients such as these who might benefit from more advanced techniques. This is a 51-years old doctor who has a family history of coronary artery disease with LDL levels persistently above 130. He came for a cardiac CT, which shows mixed plaque disease in the proximal and mid-LAD with mild stenotic disease (Figs. 1, 2). The proximal LAD (Figs 3A-3E) show a soft plaque with a calcified nodule at its distal end and the mid-LAD shows a predominantly calcified, mixed plaque (Figs. 4A-4C). The significance of these plaques is uncertain, but the presence of a combination of soft and calcified plaques should at least warrant aggressive therapy with statins and life-style management.
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