Effect of temperature increase and freezing on intravascular elastography

Intravascular ultrasound (IVUS) elastography is a technique that assesses the local strain in the vessel wall and plaque. The strain is an important parameter for characterization of different plaque components. These regions are related to plaque vulnerability. IVUS elastography was validated in vitro using human coronary and femoral arteries. These experiments were performed on specimens that were stored frozen and measured at room temperature for practical issues. The aim of this study is to determine the influence of freezing and measuring the tissues at room temperature (23 degreesC instead of 37 degreesC) on the elastic properties. Four human coronary, one carotid and one femoral arteries were first measured at 23 degreesC and next at 37 degreesC. Additionally they were stored at -80 degreesC for up to 24 h and finally measured at 23 degreesC. Acquisitions at intraluminal pressures of 80 and 100 mmHg were performed using an EndoSonics 20 MHz Visions catheter. Elastograms were determined from the IVUS rf-data (sampled at 100 MHz in 12 bits) that were obtained from a digital interface. Qualitative and quantitative analysis of the elastograms obtained from fresh and frozen specimens measured at 23 degreesC reveals that storage of the specimen at -80 degreesC has no significant influence. In vitro experiments can be performed at room temperature after storage of the tissue at -80 degreesC without significant affection of the information with respect to measuring fresh ex vivo material at body temperature, (C) 2002 Elsevier Science B.V. All rights reserved.