Objectives: The purpose of the present study was twofold: 1) to evaluate the usefulness of three-dimensional (3D) integrated backscatter (IB) intravascular ultrasound (IVUS) for quantitative tissue characterization of coronary plaques; and 2) to use this imaging technique to determine if six months of statin therapy alters the tissue characteristics of coronary plaques.
Background: Three-dimensional IVUS techniques for quantitative tissue characterization of plaque composition have not been developed.
Methods: Radiofrequency (RF) signals were obtained using an IVUS system with a 40-MHz catheter. The IB values of the RF signal were calculated and color-coded. The 3D reconstruction of the color-coded map was performed by computer software. A total of 18 IB IVUS images were captured at an interval of 1 mm in each plaque. A total of 52 patients with hyperlipidemia were randomized to treatment with pravastatin (20 mg/day, n = 17), atorvastatin (20 mg/day, n = 18), or diet (n = 17) for six months. The tissue characteristics of arterial plaque in each patient (one arterial segment per patient) were analyzed with 3D IB IVUS before and after treatment.
Results: Significant increases of fibrous volume (pravastatin: 25.4 +/- 6.5% to 28.1 +/- 6.1%; atorvastatin: 26.2 +/- 5.7% to 30.1 +/- 5.5%) and mixed lesion volume (atorvastatin: 25.5 +/- 6.6% to 28.7 +/- 5.1%) and a reduction of lipid volume (pravastatin: 25.5 +/- 5.7% to 21.9 +/- 5.3%; atorvastatin: 26.5 +/- 5.2% to 19.9 +/- 5.5%) were observed after statin therapy.
Conclusions: Statin therapy reduced the lipid component in patients with stable angina without reducing the degree of stenosis. Three-dimensional IB IVUS offers the potential for quantitative volumetric tissue characterization of coronary atherosclerosis.