2009 Volume 16 Issue 5 Pages 662-673
Aim: As an approach to tissue characterization, we attempted to classify in vivo carotid plaque tissues in terms of arterial wall elasticity instead of echogenicity on B-mode scanning and investigated whether the effect of fluvastatin on carotid elasticity can be detected in hypercholesterolemic patients. Methods: In 170 subjects, simultaneous measurements of intima-media thickness (IMT) and elastic modulus in the circumferential direction (Eθ) were performed using a new transcutaneous high-resolution Doppler technique.
Results: From the observation of various tissues, an elasticity library was obtained as follows: lipid core, 22±15 kPa; calcification, 674±384 kPa; lipid core- and calcification-free plaques, 173±69 kPa; smooth muscle, 104±32 kPa; blood clot, 85±68 kPa; fibrosis, 273±173 kPa.
The effect of fluvastatin (30 mg/day, n=62) was assessed over 12 months using the elasticity distribution and serum markers. The statin reduced low-density lipoprotein cholesterol, high-sensitivity CRP, mean IMT and mean Eθ, and increased nitrite/nitrate. In the max IMT ≥1.1 mm group, both Eθ and IMT decreased significantly. On the other hand, in the max IMT <1.1 mm group, Eθ but not IMT decreased significantly. The histogram of the subgroups showing increased Eθ with max IMT≥1.1 mm revealed a decrease in areas corresponding to Eθ of 20200 kPa (lipid/smooth muscle-rich tissue) and an increase in relatively hardened areas of <250 kPa (collagen fibers).
Conclusion: Non-invasive echographic carotid arterial elasticity measurement is useful for the classification of atherosclerotic plaques and evaluation of chronological and histopathological changes.
