Jiechen Yin

Integrated intravascular optical coherence tomography ultrasound imaging system

We report on a dual-modality optical coherence tomography (OCT) ultrasound (US) system for intravascular imaging. To the best of our knowledge, we have developed the first integrated OCT-US probe that combines OCT optical components with an US transducer. The OCT optical components mainly consist of a single-mode fiber, a gradient index lens for light-beam focusing, and a right-angled prism for reflecting light into biological tissue. A 40-MHz piezoelectric transducer (PZT-5H) side-viewing US transducer was fabricated to obtain the US image. These components were integrated into a single probe, enabling both OCT and US imaging at the same time. In vitro OCT and ultrasound images of a rabbit aorta were obtained using this dual-modality imaging system. This study demonstrates the feasibility of an OCT-US system for intravascular imaging, which is expected to have a prominent impact on early detection and characterization of atherosclerosis.

High-resolution coregistered intravascular imaging with integrated ultrasound and optical coherence tomography probe.

We report an integrated ultrasound (US) and optical coherence tomography (OCT) probe and system for intravascular imaging. The dual-function probe is based on a 50 MHz focused ring US transducer, with a centric hole for mounting OCT probe. The coaxial US and light beams are steered by a 45° mirror to enable coregistered US∕OCT imaging simultaneously. Lateral resolution of US is improved due to focused ultrasonic beam. Mirror effects on US were investigated and invitro imaging of a rabbit aorta has been carried out. The combined US-OCT system demonstrated high resolution in visualizing superficial arterial structures while retaining deep penetration of ultrasonic imaging.

Novel combined miniature optical coherence tomography ultrasound probe for in vivo intravascular imaging

We have developed a miniature integrated optical coherence tomography (OCT) ultrasound (US) probing system for intravascular imaging applications. In the OCT probe, the light coming out of a single mode fiber is focused by a gradient-index lens and then reflected by a right-angle prism from the side of the probe into the sample. It was combined with a 35 MHz PMN-PT side-viewing ultrasound transducer to obtain the ultrasound image as well. The OCT and ultrasound probes were integrated as a single probe to obtain OCT and ultrasound images simultaneously. The integrated probe has an outer diameter of 0.69 mm which, to our knowledge, is the smallest integrated OCT-US probe reported. Fast data acquisition and processing was implemented for real-time imaging. In vitro OCT and US images of human coronary artery with pathology, as well as in vivo images of normal rabbit abdominal aorta, were obtained using the integrated OCT-US probe to demonstrate its capability.

A dual-modality probe utilizing intravascular ultrasound and optical coherence tomography for intravascular imaging applications

We have developed a dual-modality biomedical imaging probe utilizing intravascular ultrasound (IVUS) and optical coherence tomography (OCT). It consists of an OCT probe, a miniature ultrasonic transducer and a fixed mirror. The mirror was mounted at the head of the hybrid probe 45° relative to the light and the ultrasound beams to change their propagation directions. The probe was designed to be able to cover a larger area in blood vessel by IVUS and then visualize a specific point at a much finer image resolution using OCT. To demonstrate both its feasibility and potential clinical applications, we used this ultrasound-guide OCT probe to image a rabbit aorta in vitro. The results offer convincing evidence that the complementary natures of these two modalities may yield beneficial results that could not have otherwise been obtained.

In vivo early detection of smoke-induced airway injury using three-dimensional swept-source optical coherence tomography

We report on the feasibility of rapid, high-resolution, 3-D swept-source optical coherence tomography (SSOCT) to detect early airway injury changes following smoke inhalation exposure in a rabbit model. The SSOCT system obtains 3-D helical scanning using a microelectromechanical system motor-based endoscope. Real-time 2-D data processing and image display at the speed of 20 frames/s are achieved by adopting the technique of parallel computing. Longitudinal images are reconstructed via an image processing algorithm to remove motion artifacts caused by ventilation and pulse. Quantitative analyses of tracheal airway thickness as well as thickness distribution along tracheal circumference are also performed based on the comprehensive 3-D volumetric data.

Quantification of airway thickness changes in smoke-inhalation injury using in-vivo 3-D endoscopic frequency-domain optical coherence tomography

Smoke inhalation injury is frequently accompanied by cyanide poisoning that may result in substantial morbidity and mortality, and methods are needed to quantitatively determine extent of airway injury. We utilized a 3-D endoscopic frequency-domain optical coherence tomography (FD-OCT) constructed with a swept-source laser to investigate morphological airway changes following smoke and cyanide exposure in rabbits. The thickness of the mucosal area between the epithelium and cartilage in the airway was measured and quantified. 3-D endoscopic FD-OCT was able to detect significant increases in the thickness of the tracheal walls of the rabbit beginning almost immediately after smoke inhalation injuries which were similar to those with combined smoke and cyanide poisoning.

Novel biomedical imaging that combines intravascular ultrasound (IVUS) and optical coherence tomography (OCT)

We have developed a new biomedical imaging probe combining intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) needle ultrasound transducers with an aperture size of 0.6 mm were fabricated. The measured center frequency and -6 dB fractional bandwidth of the PMN-PT needle ultrasound transducer were 35 MHz and 60 %, respectively. A mirror was mounted at the tip of the probe at position 45deg to change the propagation direction of the ultrasound beam and the laser beam. In vitro images of rabbit trachea and aorta forming from this combined probe have been acquired. These results demonstrate that the complementary nature of these two modalities may yield beneficial results that could not be obtained otherwise.

Advances in a fully integrated intravascular OCT-ultrasound system for cardiovascular imaging

Intracoronary optical coherence tomography (OCT) and intravascular ultrasound (IVUS) are two popular techniques for the detection and determination of atherosclerosis. IVUS allows visualization of plaques while also providing a large penetration depth to determine plaque volume. Intracoronary OCT provides the ability to capture microscopic features associated with high risk plaque. Traditionally to utilize the benefits of both modalities, separate probes and systems had to be used one at a time to image a vessel. We present work required to create a combined OCT IVUS system capable of simultaneous imaging to detect atherosclerotic plaques. A novel integrated probe of size 0.69 mm OD featuring sequential placement of components was created to acquire co-registered images within small coronary vessels. By utilizing commercial graphics processing units (GPUs) real time visualization of acquired data is possible up to a maximum 48 frames per second per channel. In vitro studies on human coronary artery samples as well as in vivo studies in rabbits and pigs show various plaque buildups in both OCT and IVUS images which match histology results, demonstrating the capabilities of the system.

Combining OCT and a fluorescence intensity imaging method for atherosclerosis detection

Coronary heart disease (like myocardial infarction) is caused by atherosclerosis. It cause over 30% of all deaths in North America and are the most common cause of death in European men under 65 years of age and the second most common cause in women. To diagnose this atherosclerosis before it gets rupture is the most effect way to increase the chance of survival for patients who suffer from this disease. The crucial tusk is how to find out vulnerable plaques. In resent years optical coherence tomography (OCT) has become a very useful tool for intravascular imaging, since it has high axial and transverse resolution. OCT can tell the detail structure inside the plaque like the thickness of plaque cap which is an important factor to identify vulnerable plaques. But we still need to find out the biochemical characteristics that is unique for vulnerable plaques (like inflammation). Fluorescence molecular imaging is a standard way to exam the biochemical property of biological samples. So we integrate these two techniques together into one probe. Our probe is comprised of a double-clad fiber (DCF) and a grin lens, and rotates with a micro mirror in front. The single-mode inner core of the DCF transmits both OCT and fluorescence excitation light, and the multimode inner cladding is used to detect fluorescence signal. In vitro result shows that this is a possible way for more accurate diagnose of vulnerable plaques.

Miniature integrated optical coherence tomography (OCT) - ultrasound (US) probe for intravascular imaging

A miniature integrated optical coherence tomography (OCT) - ultrasound (US) probing system for real-time intravascular imaging has been developed. The outer diameter of the integrated probe is 0.69 mm, which is small enough for imaging in human coronary arteries. This probe, which has high resolution and deep tissue penetration, is designed to identify vulnerable atherosclerotic plaques in coronary arteries. The first in vivo images of a rabbit abdominal aorta obtained by the integrated OCT-US probe are presented.