High resolution IVUS elastography in patients

Intravascular ultrasound (IVUS) elastography is a new imaging technique that reveals local mechanical properties of the vascular wall by measuring the local strain. Last year, low resolution elastograms (64 angles) were presented. In this study, we present high resolution elastograms. Patients (n=8) referred for Percutaneous Transluminal Coronary Angioplasty were investigated with an EndoSonics InVision echoapparatus. The beam-formed image mode (512 angles) ultrasound data (Fc = 20 MHz) was acquired with an acquisition system that was assembled in collaboration with EndoSonics. Elastograms were determined using data acquired near end-diastole. In this phase of the pressure cycle, catheter motion was minimal. Frames with a pressure difference of approx. 5 mmHg were taken to determine the elastograms. Elastograms of soft, calcified and stented plaques were determined. The elastogram of a soft plaque, as identified from the deformation during the pressure cycle, reveals strain values up to 2% with increased strain regions at the shoulders of the plaque. Calcified material, as identified from the echogram, shows strain values of 0-0.2%. The elastogram of stented plaques reveals very low strain values, except for two regions: these are between the stent struts and at the shoulders of the plaque.