Gary J. Tearney

HIGH-RESOLUTION OPTICAL COHERENCE TOMOGRAPHIC IMAGING USING A MODE-LOCKED TI:AL2O3 LASER SOURCE

A Kerr-lens mode-locked Ti:Al(2)O(3) oscillator, optimized for minimal coherence length, is demonstrated as a high-power source for high-resolution optical coherence tomographic imaging. Dispersion compensation and heterodyne noise rejection are demonstrated to yield in situ images of biological tissues with 3.7-mum resolution and 93-dB dynamic range.

A Case of Lipid Core Plaque Progression and Rupture at the Edge of a Coronary Stent: Elucidating the Mechanisms of Drug-Eluting Stent Failure

Received October 20, 2009; accepted January 20, 2010. Understanding the mechanisms of coronary drug-eluting stent (DES) failure remains relevant in light of concerns brought on by clinical reports of life-threatening late and very late stent thrombosis and by autopsy studies showing delayed and incomplete healing inside the stents, which may be related to underlying necrotic lipid core.1 Frequency-domain optical coherence tomography, also known as optical frequency-domain imaging (OFDI), is a new intracoronary imaging technology that enables 3-dimensional visualization of coronary structure in vivo at a resolution (≈6 μm) sufficient to identify many microscopic features of the coronary wall and stents.2 Here, we present a case of late DES failure that was imaged by OFDI at the time of stent implantation and 15 months later on presentation with unstable angina. The patient was a 52-year-old man with hypertension, dyslipidemia, a family history of coronary artery disease, and prior myocardial infarction in 1998. The patient presented again to the Lahey Clinic in 2007 (baseline), complaining of rest and exertional chest pain and with a positive stress test.2 Angiography revealed a 99% stenosis in the right coronary artery near the bifurcation of the posterior descending artery (Figure 1A). Deployment of a 3×18-mm sirolimus DES (Cypher Cordis, Miami, Fla) was performed with a good result (Figure 1B and 1C). The operators were blinded to the results of OFDI imaging. The patient was maintained on dual antiplatelet therapy (aspirin and clopidogrel) and a statin. The patient returned 15 months later with symptoms of unstable angina. Diagnostic angiography was performed, followed by OFDI of the right coronary artery. The angiogram revealed a 95% right …

High-speed, high-resolution optical coherence tomography with use of femtosecond lasers

Optical coherence tomography (OCT) is a recently developed technique for performing cross-sectional imaging of internal microstructure in biological and other systems.1

Interventional optical coherence tomography for surgical guidance

Optical coherence tomography (OCT) uses low-coherence interferometry to perform optical ranging measurements within biological tissue. Recent advances in OCT technology have permitted high-speed imaging at 4-8 frames/s. In vivo catheter/endoscope-based OCT imaging has recently been performed in a rabbit. OCT has also shown a feasibility for surgical diagnostics and for assessing microsurgical repairs of vessels and nerves. In this study, we investigate the use of high-speed OCT as an interventional imaging modality for surgical guidance. OCT can provide continuous image-guidance for the precise delivery of high-power laser radiation and selective ablation of diseased tissue.

Real time monitoring of laser ablation for treatment of Barrett’s Esophagus by Optical Coherence Tomography

We present an integrated imaging/laser-ablation technique for treatment of Barrett’s Esophagus using Optical Coherence Tomography. The technique provides real time feedback during ablation on a micron scale and provides more accurate control of treatment volume.

946-108 High Resolution Imaging of Human Arterial Walls Via Optical Coherence Tomography

Optical coherence tomography (OCT) is a recently developed technology which can perform micron scale, cross sectional tomographic imaging. OCT performs imaging using interferometric optical ranging of low coherence infrared light or ultrashort laser pulses which are backscattered from tissue. This technique is analogous to the reflected acoustical wave measurements of conventional B mode ultrasound. In this study, two dimensional cross sectional images were generated of in vitro human aorta and coronary artery sections obtained postmortem. The microstructure of normal and atherosclerotic tissue was displayed as a false color or grey scale image. The bandwidth of the photodiode source (1300 nm) allowed a resolution of 20 microns, almost 10 times greater than conventional intravascular ultrasound. Different morphologies including fatty, fibrous, and water based tissue, were well differentiated in the images and corresponded to histologic sections. Imaging was possible with up to 1 mm penetration into the tissue with little attenuation from heavy calcification. The typical image acquisition time was in the range of 2–3 seconds. A more detailed analysis of the optical properties of relatively uniform, structurally distinct tissues, such as adipose, skeletal muscle, and tendon, was performed to further confirm the contrast between fat, muscle, and connective tissue. The contrast ratios of muscle, tendon, and fat, were measured to be 1:78:22, respectively. The effective refractive indices and optical penetration depths in different tissue types were also measured. OCT is a promising new technology for high resolution “optical biopsy”. It does not require direct contact with the vessel wall and could be performed via a catheter integrated with a relatively inexpensive fiberoptic bundle. Future studies utilizing currently available femtosecond lasers are expected to both increase the resolution of OCT, which is dependent on bandwidth or pulse duration. to ≈3–4 microns and allow visualization of structures deeper into tissues.

Ultra-high resolution video rate in vivo retinal imaging with spectral domain optical coherence tomography

Ultra-high resolution images of the human retina in vivo were acquired at rates of 10.000 and 29.000 A-lines per second at a 99% duty cycle and axial resolution in the retina of 3.6 µm.

Video-rate spectral domain optical coherence tomography

An ultra-high SD-OCT system continuously obtained in vivo images of a human retina at a speed of 29.3 kHz. A 3-D volume of the optic nerve head was constructed from the data acquired.

Monitoring coronary artery stent deployment in living human patients with optical coherence tomography

Summary form only given. In this preliminary study, we have demonstrated that intravascular OCT imaging following stent deployment is feasible and permits the high resolution visualization of detailed vessel wall structure within and adjacent to stents. The data obtained from imaging eleven stents in ten patients indicates that with OCT: (1) stent strut apposition to the vessel lumen can be accurately determined, (2) superficial calcium can be identified within stents, (3) the detailed structure of the vessel wall can be visualized within stents, (4) dissections within and adjacent to stents can be identified, and (5) even small protrusions of tissue through stent struts can be quantified. The improved ability of OCT to visualize vessel and stent structure may provide a new tool for accurately monitoring stent deployment and understanding in-stent restenosis.

Noninvasive imaging of oral precancer using optical coherence tomography

trolled studies. Both surgery and radiation therapy (XRT) have been advocated as treatment methods. We report a unique hypopharyngeal desmoid tumor controlled with XRT and review the literature. Methods: Case report with 1-year posttreatment follow-up. No previous similar case was identified with a careful MEDLINE search. Results: The patient is a 33-year-old man who presented with a 1-month history of neck fullness and dysphagia. Imaging revealed a 5-cm hypopharyngeal mass with significant narrowing of the upper airway. Direct laryngoscopy, tracheotomy, gastrostomy, and biopsy were performed. Pathologic examination revealed a moderately cellular spindle cell lesion. Desmoid tumor was diagnosed. Complete surgical resection would have required total pharyngolaryngectomy with cervical esophagectomy and may have left residual disease at the carotid arteries. Radiation therapy was recommended. After a total dose of 60 Gy, the patient was decannulated and resumed a normal diet. He had a complete clinical and radiographic response, remains free of disease after 1-year follow-up, and has normal speech and swallowing function. Conclusion: We report the first case of a hypopharyngeal desmoid tumor. Primary XRT resulted in regression of the tumor, avoiding total pharyngolaryngectomy. XRT remains an attractive management option either in place of or after surgery for selected high-risk cases.