Multi-frequency intravascular ultrasound (IVUS) imaging

Abstract

Acute coronary syndrome (ACS) is frequently associated with the sudden rupture of a vulnerable atherosclerotic plaque within the coronary artery. Several unique physiological features, including a thin fibrous cap accompanied by a necrotic lipid core, are the targeted indicators for identifying the vulnerable plaques. Intravascular ultrasound (IVUS), a catheter-based imaging technology, has been routinely performed in clinics for more than 20 years to describe the morphology of the coronary artery and guide percutaneous coronary interventions. However, conventional IVUS cannot facilitate the risk assessment of ACS because of its intrinsic limitations, such as insufficient resolution. Renovation of the IVUS technology is essentially needed to overcome the limitations and enhance the coronary artery characterization. In this paper, a multi-frequency intravascular ultrasound (IVUS) imaging system was developed by incorporating a higher frequency IVUS transducer (80 to 150 MHz) with the conventional IVUS (30–50 MHz) system. The newly developed system maintains the advantage of deeply penetrating imaging with the conventional IVUS, while offering an improved higher resolution image with IVUS at a higher frequency. The prototyped multi-frequency catheter has a clinically compatible size of 0.95 mm and a favorable capability of automated image co-registration. In vitro human coronary artery imaging has demonstrated the feasibility and superiority of the multi-frequency IVUS imaging system to deliver a more comprehensive visualization of the coronary artery. This ultrasonic-only intravascular imaging technique, based on a moderate refinement of the conventional IVUS system, is not only cost-effective from the perspective of manufacturing and clinical practice, but also holds the promise of future translation into clinical benefits.

3D printing of piezoelectric element for energy focusing and ultrasonic sensing

“…[1][2][3][4][5][6] However, conventional manufacturing processes such as etching and dicing for piezoelectric ceramics fabrication have limited capability of achieving complex geometry and high resolution(X-Y resolution<25μm). Moreover, mechanical stress caused by the traditional machining processes can result in grain pullout, strength degradation and depolarization of the near surface region, which will led to significant degradation in piezoelectric device performance.…”

A Review of Intravascular Ultrasound-based Multimodal Intravascular Imaging

“…56 Shown in Figure 4, a clinically compatible size catheter (0.95 mm OD) and an integrated dual-channel ultrasonic system were prototyped and evaluated for in vitro human coronary artery imaging, with back-to-back arrangement of the two transducers to achieve image co-registration. The multi-frequency IVUS system was able to achieve a more comprehensive visualization of the coronary artery as compared with the integrated IVUS-OCT system by imaging the whole plaque volume using the low frequency transducer with deep penetration and by measuring the thin fibrous cap using the ultra-high frequency transducer with finer resolution.…”

High-speed intravascular photoacoustic imaging at 17 μm with a KTP-based OPO

“…Imaging modalities, which include magnetic resonance angiography, computed tomography angiography and X-ray angiography are used primarily to image the encroachment of plaques on the artery lumen, which is not always predictive of lipid core size or plaque vulnerability. Among the current interventional imaging approaches, intravascular ultrasound (IVUS) lacks the chemical selectivity to determine the lipid-composition of the vessel wall [8], even for the most recently demonstrated multi-frequency IVUS method [9]. The so-called "virtual histology" based on IVUS image processing has been challenged [10].…”