Nanoshell-enhanced optical coherence tomography (OCT) is a novel technique with the potential for molecular imaging and improved disease detection. However, optimization of this approach will require a quantitative understanding of the influence of nanoshell parameters on detected OCT signals. In this study, OCT was performed at 1310 nm in water and turbid tissue-simulating phantoms to which nanoshells were added. The effect of nanoshell concentration, core diameter, and shell thickness on signal enhancement was characterized. Experimental results indicated trends that were consistent with predicted optical properties-a monotonic increase in signal intensity and attenuation with increasing shell and core size. Threshold concentrations for a 2-dB OCT signal intensity gain were determined for several nanoshell geometries. For the most highly backscattering nanoshells tested-291-nm core diameter, 25-nm shell thickness-a concentration of 10(9) nanoshells/mL was needed to produce this signal increase. Based on these results, we discuss various practical considerations for optimizing nanoshell-enhanced OCT. Quantitative experimental data presented here will facilitate optimization of OCT-based diagnostics and may also be relevant to other reflectance-based approaches as well.

MHI detected cervical cancer precursors at a rate greater than that obtained by a simultaneously collected Pap smear.

We have developed a novel method to study the effects of electrical stimulation of the local retina directly under an epiretinal stimulus electrode in real time. Using optical coherence tomography (OCT) and a superfused retinal eyecup preparation, we obtained high-resolution images of the rabbit retina directly under an optically transparent saline-filled fluoropolymer stimulation tube electrode. During OCT imaging, 50 Hz trains of biphasic current pulses 1 ms/phase (23-749 µC cm(-2) ph(-1)) were applied to the retinal surface for 5 min. After imaging, the stimulated regions were stained with the dye propidium iodide (PI) to reveal cytotoxic damage. Pulse train stimulation at 44-133 µC cm(-2) ph(-1) had little effect on the retina; however, trains ≥442 µC cm(-2) ph(-1) caused increases in the reflectance of the inner plexiform layer (IPL) and edema. The damage seen in retinal OCT images matched the pattern observed in histological sections, and in the PI staining. With pulse trains ≥442 µC cm(-2) ph(-1), rapid increases in the reflectivity of the IPL could be observed under the stimulus electrode. Below the electrode, we observed a ring-like pattern of retinal detachment in the subretinal space. The OCT imaging method may be useful for analyzing overstimulation of neuronal tissue by electrodes in many brain regions.

Abstract. Optical coherence tomography (OCT) is a rapidly growing imaging modality, particularly in the field of ophthalmology. Accurate early diagnosis of diseases requires consistent and validated imaging performance. In contrast to more well-established medical imaging modalities, no standardized test methods currently exist for OCT quality assurance. We developed a retinal phantom which mimics the thickness and near-infrared optical properties of each anatomical retinal layer as well as the surface topography of the foveal pit. The fabrication process involves layer-by-layer spin coating of nanoparticle-embedded silicone films followed by laser micro-etching to modify the surface topography. The thickness of each layer and dimensions of the foveal pit are measured with high precision. The phantom is embedded into a commercially available, water-filled model eye to simulate ocular dispersion and emmetropic refraction, and for ease of use with clinical OCT systems. The phantom was imaged with research and clinical OCT systems to assess image quality and software accuracy. Our results indicate that this phantom may serve as a useful tool to evaluate and standardize OCT performance. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

H ealth care professionals encounter multiple dilemmas with the surveillance, diagnosis, and management of women with cervical neoplasia. An imperfect screening test, a lengthy Papanicolaou (Pap) smear collection to notification interval, and a substantial patient noncompliance rate with recommended practices may all adversely impact the screening process [1][2][3][4][5][6][7][8]. Cervical neoplasia is suspected from an abnormal screening Pap smear or positive triage test for oncogenic human papillomavirus (HPV) DNA that is localized and detected by specific epithelial features noted during colposcopic examination of the lower genital tract. The diagnosis is confirmed by histologic results obtained from sampling the ectocervix and endocervical canal, when deemed necessary [9]. When results from these evaluations are considered collectively, optimal management ensues. Most of the tests involve a subjective appraisal that varies considerably and depends on specimen or anatomic variation, as well as evaluator expertise. Thus, diagnoses may be influenced adversely by technical issues and are not made consistently at an expert level; the diagnoses also are not always reproducible. AbstractObjective. To determine the ability of Multimodal Hyperspectral Imaging (MHI) to noninvasively detect, localize and diagnose cervical neoplasia.Materials and Methods. The cervical epithelium was interrogated by MHI using tissue fluorescence and reflectance measurements after the probe was placed on the ectocervix. A Papanicolaou smear was taken, and a colposcopic examination was performed and cervical histologic specimens were collected, when indicated. MHI and Pap smear sensitivity and specificity data were compared with colposcopic and histologic results.Results. Nineteen patients had CIN2 or higher, 30 had CIN1, 34 had benign cellular changes or metaplasia, and 28 were normal by both Pap smear and colposcopic examination. At equal specificity (70%) for both tests, the sensitivity of MHI was 97%, compared to 72% for the Pap smear.Conclusion. MHI detected cervical cancer precursors at a rate greater than that obtained by a simultaneously collected Pap smear.