High-resolution Cross-sectional Imaging Technique Research Articles

Initial Study for the Determination of the Sequence of Intersecting Lines between Gel Pens and Seals by Optical Coherence Tomography.

Determining the sequence of intersecting lines is a significant issue in the forensic document examination that can reveal the fraud or distinguish between different allegations. Optical coherence tomography (OCT) is a high-resolution cross-sectional imaging technique that has been introduced into forensic science field recently. The potential of OCT as a novel method to determine the sequence of intersecting lines was examined for the first time. In this study, a spectral-domain OCT system with a center wavelength of 900nm was employed to perform nondestructive examination on determining the sequence of 18 heterogeneous intersecting line samples produced using three types of gel pens and three brands of stamp pad ink seals. Two-dimensional (2D) cross-sectional, and three-dimensional (3D) volumetric images of the intersecting lines were obtained by the OCT system. Several features were noted and analyzed to successfully determine the sequence of all the 18 samples. Blind tests were also conducted to demonstrate the effectiveness of OCT technique. The results illustrate that OCT technology can provide an effective and accurate method for sequencing intersecting lines of gel pen ink and seal ink, which may complement the conventional methods used in the examination of questioned documents.

Scalable double regularization for 3D Nano-CT reconstruction

Nano-CT (computerized tomography) has emerged as a non-destructive high-resolution cross-sectional imaging technique to effectively study the sub-μm pore structure of shale, which is of fundamental importance to the evaluation and development of shale oil and gas. Nano-CT poses unique challenges to the inverse problem of reconstructing the 3D structure due to the lower signal-to-noise ratio (than Micro-CT) at the nano-scale, increased sensitivity to the misaligned geometry caused by the movement of object manipulator, limited sample size, and a larger volume of data at higher resolution. We propose a scalable double regularization (SDR) method to utilize the entire dataset for simultaneous 3D structural reconstruction across slices through total variation regularization within slices and L1 regularization between adjacent slices. SDR allows information borrowing both within and between slices, contrasting with the traditional methods that usually build on slice by slice reconstruction. We develop a scalable and memory-efficient algorithm by exploiting the systematic sparsity and consistent geometry induced by such Nano-CT data. We illustrate the proposed method using synthetic data and two Nano-CT imaging datasets of Jiulaodong (JLD) shale and Longmaxi (LMX) shale acquired in the Sichuan Basin. These numerical experiments show that the proposed method substantially outperforms selected alternatives both visually and quantitatively.

NSAID Enteropathy: A Review of the Disease Entity and Its Distinction from Crohn’s Enteropathy

AbstractNonsteroidal anti-inflammatory drug (NSAID)-induced enteropathy is an increasingly recognized entity. Patients of older age and those suffering from conditions such as arthritis requiring long term NSAIDs are thought to be at greater risk. Introduction of enteroscopic techniques has greatly improved understanding of NSAID-related small intestinal injury. Complementary high-resolution cross-sectional imaging techniques aid in initial evaluation and for exclusion of alternative etiology. Erosions, superficial ulcerations, and short segment strictures are the most commonly described findings. The diagnosis of the condition lies in obtaining relevant history in addition to a high degree of suspicion during investigation of anemia, obscure gastrointestinal bleeding, small bowel obstruction, and protein losing enteropathy. Herein, the authors present a review of pathogenesis and imaging findings of NSAID enteropathy with particular emphasis on distinction from Crohn’s enteropathy.

Hepatocellular carcinomas and their mimics

High resolution cross-sectional imaging techniques means that even small, well-differentiated hepatocellular tumors can also be diagnosed with biopsy. In cirrhotic liver tissue, macroregenerative and dysplastic nodules must be discriminated from hepatocellular cancer (HCC). In non-cirrhotic liver tissue the differential diagnosis includes hepatocellular adenoma, macroregeneratory nodules, fibrolamellar carcinoma, as well as primary tumors and metastases. The diagnostic procedure includes matrix diagnosis of the tumor-bearing liver tissue, cyto- and histomorphologic analysis including capillarization of vascular bed, and adapted immunohistological testing with antibodies which underline possible malignancy or hepatocellular differentiation. Aflow chart for the diagnosis of hepatocellular carcinomas and their mimics on liver biopsies is presented.

Nano-Computed Tomography: Technique and Applications.

Nano-computed tomography (nano-CT) is an emerging, high-resolution cross-sectional imaging technique and represents a technical advancement of the established micro-CT technology. Based on the application of a transmission target X-ray tube, the focal spot size can be decreased down to diameters less than 400 nanometers (nm). Together with specific detectors and examination protocols, a superior spatial resolution up to 400 nm (10 % MTF) can be achieved, thereby exceeding the resolution capacity of typical micro-CT systems. The technical concept of nano-CT imaging as well as the basics of specimen preparation are demonstrated exemplarily. Characteristics of atherosclerotic plaques (intraplaque hemorrhage and calcifications) in a murine model of atherosclerosis (ApoE (-/-)/LDLR(-/-) double knockout mouse) are demonstrated in the context of superior spatial resolution in comparison to micro-CT. Furthermore, this article presents the application of nano-CT for imaging cerebral microcirculation (murine), lung structures (porcine), and trabecular microstructure (ovine) in contrast to micro-CT imaging. This review shows the potential of nano-CT as a radiological method in biomedical basic research and discusses the application of experimental, high resolution CT techniques in consideration of other high resolution cross-sectional imaging techniques. Nano-computed tomography is a high resolution CT-technology for 3D imaging at sub-micrometer resolution. The technical concept bases on a further development of the established ex-vivo-micro-CT technology. By improvement of the spatial resolution, structures at a cellular level become visible (e.g. osteocyte lacunae).

English

PURPOSE: This study aimed to assess the severity of Macular Edema in patients with diabetic macular edema using Spectral Domain Optical Coherence Tomography (SD-OCT), a technique for high-resolution cross-sectional imaging of the retina and to describe various morphologic patterns of diabetic macular edema (DME) demonstrated by optical coherence tomography (OCT) and correlate them with visual acuity. METHODS: A total of 158 eyes of 100 patients with diabetic retinopathy were studied. Optical coherence tomograms were obtained in a radial spoke pattern centered on the fovea. Macular thickness was reported numerically as averages in each of nine regions. All patients with DME underwent OCT evaluation. The OCT scans were evaluated for the presence of diffuse retinal thickening (DRT), cystoid macular edema (CME), posterior hyaloidal traction (PHT), serous retinal detachment (SRD), and traction retinal detachment (TRD), the retinal thickness was measured and correlated with visual acuity. RESULTS: Optical coherence tomography was able to quantify the development of both foveal and extrafoveal macular thickening. The (Mean±SD) Central Macular thickness was (502.8±121.9) in eyes with NPDR and (534.3±152.1) in eyes with PDR. Foveal thickness measured by OCT was highly correlated with visual acuity. Two hundred two OCT scans of 158 eyes of 100 patients were identified. OCT revealed five morphologic patterns of DME: DRT (61.88%); CME (24.75%), SRD without PHT (6.93%); PHT without TRD (5.45%); PHT with TRD (0.99%).Increasing retinal thickness in all patterns was significantly correlated with worse visual acuity (P <0.05). CONCLUSIONS: Optical coherence tomography was a useful technique for quantifying macular thickness in patients with diabetic macular edema. DME exhibits five different morphologic patterns on OCT. There is a significant correlation between retinal thickness and visual acuity.

418 Volumetric Microscopy Biopsy Guidance Platform for Barrett's Esophagus: a Pilot Study

Biopsy surveillance protocols for the assessment of Barrett's esophagus can be subject to sampling errors, resulting in diagnosic uncertainty. Optical frequency domaing imaging (OFDI) is a high-resolution cross-sectional imaging technique that can be used to conduct volumetric laser endomicroscopy (VLE) of the entire distal esophagus. We have recently developed a balloon-based OFDI system with laser marking capabilities to guide biopsy site selection with the goal of reducing the sampling error associated with the surveillance of Barrett's esophagus.

Radiographic evaluation of the incidental adrenal lesion

The detection of incidental adrenal masses has increased substantially with the advent and widespread use of high-resolution cross-sectional imaging techniques such as CT and MRI. The work-up and treatment of these incidentally found adrenal masses continue to be a clinical challenge for radiologists, endocrinologists, and adrenal surgeons. The approach to the evaluation of most of these adrenal masses depends on the radiologic appearance of the lesion, and whether the patient has a known underlying malignancy. The aim of this article is to review imaging features of pathologic abnormalities of the adrenal gland. Recent advances in noninvasive imaging methods that attempt to differentiate benign from malignant lesions also are addressed.

Endoscopic Doppler optical coherence tomography in the human GI tract: initial experience

Expanding the current endoscopic optical coherence tomography (OCT) system with Doppler capability may augment this novel high-resolution cross-sectional imaging technique with functional blood flow information. The aim of this feasibility study was to assess the clinical feasibility of an endoscopic Doppler OCT (EDOCT) system in the human GI tract. During routine endoscopy, 22 patients were imaged by using a prototype EDOCT system, which provided color-Doppler and velocity-variance images of mucosal and submucosal blood flow at one frame per second, simultaneously with high-spatial-resolution (10-25 mum) images of tissue microstructure. The images were acquired from normal GI tract and pathologic tissues. Subsurface microstructure and microcirculation images of normal and pathologic GI tissues, including Barrett's esophagus, esophageal varices, portal hypertensive gastropathy, gastric antral vascular ectasia, gastric lymphoma, and duodenal adenocarcinoma, were obtained from 72 individual sites in vivo. Differences in vessel diameter, distribution, density, and blood-flow velocity were observed among the GI tissue pathologies imaged. To our knowledge, this is the first study to demonstrate the feasibility of EDOCT imaging in the human GI tract during routine endoscopy procedures. EDOCT may detect the different microcirculation patterns exhibited by normal and diseased tissues, which may be useful for diagnostic imaging and treatment monitoring.

Artifacts in optical coherence tomography topographic maps

OVER THE LAST FEW YEARS, OPTICAL COHERENCE tomography (OCT) has become an indispensable technique for high-resolution cross-sectional imaging of the macula and optic nerve. One of the most useful applications of OCT is its ability to sensitively and reproducibly monitor retinal thickness. Although originally developed as a technique to evaluate diabetic macular edema, 1 Hee M.R. Puliafito C.A. Duker J.S. et al. Topography of diabetic macular edema with optical coherence tomography. Ophthalmology. 1998; 105: 360-370 Abstract Full Text PDF PubMed Scopus (543) Google Scholar in many institutions the OCT topographic map is becoming a de facto standard for evaluating other macular conditions and therapies for age-related macular degeneration. In this issue, Ray and associates examine artifacts which may appear in OCT topographic maps. 2 Ray R. Stinnett S.S. Jaffe G.J. Evaluation of image artifact produced by optical coherence tomography of retinal pathology. Am J Ophthalmol. 2005; 1 Google Scholar

In vivo endoscopic optical coherence tomography of the human gastrointestinal tract--toward optical biopsy.

Optical coherence tomography (OCT) is a new technique for high-resolution cross-sectional imaging using infrared light. It has over 10 times the resolution of the currently available ultrasonography. Although in vitro studies have suggested its potential for gastrointestinal imaging, in vivo studies have not been possible so far on account of technical limitations. We describe here the first clinical study of OCT during routine endoscopy obtaining high resolution images of the normal esophageal, gastric, and colonic mucosa. Portable OCT equipment and a fiberoptic-based flexible probe for endoscopic use have been developed by the authors. Differences in the optical properties of epithelium, lamina propria, muscularis mucosae, and submucosa enabled distinction of the mucosal architecture. Owing to the low penetration depth (1 mm) and high resolution (10 microm), OCT images may become comparable to mucosal histological findings. Image acquisition time was 1.5 seconds, and the entire procedure was completed within 5 minutes. Endoscopic OCT images of colonic adenoma and carcinoma were also studied and compared with the corresponding histology. The newly developed portable OCT equipment and flexible fiberoptic probe makes OCT a promising method for endoscopic "optical biopsy".

Topography of diabetic macular edema with optical coherence tomography

This study aimed to develop a protocol to screen and monitor patients with diabetic macular thickening using optical coherence tomography (OCT), a technique for high-resolution cross-sectional imaging of the retina. A cross-sectional pilot study was conducted. A total of 182 eyes of 107 patients with diabetic retinopathy, 55 eyes from 31 patients with diabetes but no ophthalmoscopic evidence of retinopathy, and 73 eyes from 41 healthy volunteers were studied. Six optical coherence tomograms were obtained in a radial spoke pattern centered on the fovea. Retinal thickness was computed automatically from each tomogram at a total of 600 locations throughout the macula. Macular thickness was displayed geographically as a false-color topographic map and was reported numerically as averages in each of nine regions. Correlation of OCT with slit-lamp biomicroscopy, fluorescein angiography, and visual acuity was measured. Optical coherence tomography was able to quantify the development and resolution of both foveal and extrafoveal macular thickening. The mean +/- standard deviation foveal thickness was 174 +/- 18 microns in normal eyes, 179 +/- 17 microns in diabetic eyes without retinopathy, and 256 +/- 114 microns in eyes with nonproliferative diabetic retinopathy. Foveal thickness was highly correlated among left and right eyes of normal eyes (mean +/- standard deviation difference of 6 +/- 9 microns). Foveal thickness measured by OCT correlated with visual acuity (r2 = 0.79). A single diabetic eye with no slit-lamp evidence of retinopathy showed abnormal foveal thickening on OCT. Optical coherence tomography was a useful technique for quantifying macular thickness in patients with diabetic macular edema. The topographic mapping protocol provided geographic information on macular thickness that was intuitive and objective.

Quantitative Assessment of Macular Edema with Optical Coherence Tomography

Objective: To evaluate optical coherence tomography, a new technique for high-resolution cross-sectional imaging of the retina, for quantitative assessment of retinal thickness in patients with macular edema. Design: Survey examination with optical coherence tomography of patients with macular edema. Setting: Referral eye center. Patients: Forty-nine patients with the clinical diagnosis of diabetes or diabetic retinopathy and 25 patients with macular edema secondary to retinal vein occlusion, uveitis, epiretinal membrane formation, or cataract extraction. Main Outcome Measures: Correlation of optical coherence tomograms with slit-lamp biomicroscopy, fluorescein angiography, and visual acuity. Results: Optical coherence tomograms of cystoid macular edema closely corresponded to known histopathologic characteristics. Quantitative measurement of retinal thickness is possible because of the well-defined boundaries in optical reflectivity at the inner and outer margins of the neurosensory retina. Serial optical coherence tomographic examinations allowed tracking of both the longitudinal progression of macular thickening and the resolution of macular edema after laser photocoagulation. In patients with diabetic retinopathy, measurements of central macular thickness with optical coherence tomography correlated with visual acuity, and optical coherence tomography was more sensitive than slit-lamp biomicroscopy to small changes in retinal thickness. Conclusions: Optical coherence tomography appears useful for objectively monitoring retinal thickness with high resolution in patients with macular edema. It may eventually prove to be a sensitive diagnostic test for the early detection of macular thickening in patients with diabetic retinopathy.