Ahmad Edris

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.

Use of an oxygen-carrying blood substitute to improve intravascular optical coherence tomography imaging

Optical coherence tomography (OCT) is a catheter-based imaging technology with powerful resolution capable of identifying vulnerable plaques and guiding coronary intervention. However, a significant limitation of intravascular OCT imaging is its attenuation by blood. We propose that the use of an oxygen-carrying blood substitute could potentially optimize OCT image quality. Surgical isolation of the descending thoracic aorta of six rabbits is performed, followed by intravascular OCT imaging of the abdominal aorta. Perfluorodecalin (PFD) is oxygenated using a bubble-through technique with 100% oxygen. OCT imaging is performed and compared using three different flushing modalities: PFD; saline; and blood. OCT imaging of the rabbit abdominal aorta is successful in all of the subjects. In each of the six studied subjects, flushing with PFD consistently provides dramatically better imaging of the vessel wall tissue structures. OCT image quality is highly dependent on the ability of the flushing modality to remove blood from the imaging field. From this proof-of-concept study, we demonstrate that endovascular flushing with an oxygen-carrying blood substitute (PFD) is optically superior to saline flushing for intravascular imaging.

Early recognition of catheter-induced left main coronary artery vasospasm: Implications for revascularization†

Catheter‐induced left main coronary artery (LMCA) vasospasm is a rare complication of coronary angiography that confounds the decision for coronary artery bypass graft (CABG) surgery. We report two cases of catheter‐induced LMCA vasospasm. The first case was a 68‐year‐old woman who presented 6 years after CABG for presumed severe LMCA atherosclerotic disease. Coronary angiography demonstrated totally occluded CABGs and normal native coronary arteries, including a normal LMCA. The second case was a 56‐year‐old man with severe LMCA stenosis, who was scheduled for unprotected LM percutaneous coronary intervention (PCI). Repeat angiography 2 days later showed no stenosis. These cases emphasize the need for meticulous technique and a high index of suspicion of LMCA vasospasm. Intravascular ultrasound (IVUS) at the time of angiography may help to identify minimal atherosclerotic disease suggesting vasospasm. Alternatively, noninvasive testing, such as Computed Tomography (CT) angiography, may diagnose LM spasm in these patients prior to CABG surgery.

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.

Intramyocardial hemorrhage after percutaneous coronary intervention.

(Echocardiography 2012;29:E50‐E51)

Integrated optical coherence tomography - ultrasound system and miniaturized probes for intravascular imaging

We report on the development of a multimodal optical coherence tomography (OCT) - ultrasound (US) system and miniaturized OCT-US probe for intravascular imaging. Both OCT optical components and a US transducer were integrated into a single probe, enabling both OCT and US imaging at the same time. A miniaturized OCT-US probe using a single element transducer was designed with a maximum outer diameter of 0.8 mm, which is suitable for in vivo intravascular imaging. The integrated OCT-US imaging system adopted a two-channel data acquisition card to digitize both OCT and US signals. Simultaneous OCT and US data processing and image display were also achieved using our home-developed software. In vitro OCT and US imaging of human aortic tissue was performed using this multimodal imaging system, which demonstrated the feasibility of the OCT-US system in intravascular imaging and its potential in detection of atherosclerotic plaques.