Optical Coherence Tomography For Detection Research Articles

Explainable ensemble learning method for OCT detection with transfer learning.

The accuracy and interpretability of artificial intelligence (AI) are crucial for the advancement of optical coherence tomography (OCT) image detection, as it can greatly reduce the manual labor required by clinicians. By prioritizing these aspects during development and application, we can make significant progress towards streamlining the clinical workflow. In this paper, we propose an explainable ensemble approach that utilizes transfer learning to detect fundus lesion diseases through OCT imaging. Our study utilized a publicly available OCT dataset consisting of normal subjects, patients with dry age-related macular degeneration (AMD), and patients with diabetic macular edema (DME), each with 15 samples. The impact of pre-trained weights on the performance of individual networks was first compared, and then these networks were ensemble using majority soft polling. Finally, the features learned by the networks were visualized using Grad-CAM and CAM. The use of pre-trained ImageNet weights improved the performance from 68.17% to 92.89%. The ensemble model consisting of the three CNN models with pre-trained parameters loaded performed best, correctly distinguishing between AMD patients, DME patients and normal subjects 100% of the time. Visualization results showed that Grad-CAM could display the lesion area more accurately. It is demonstrated that the proposed approach could have good performance of both accuracy and interpretability in retinal OCT image detection.

The accuracy of detailed analysis of optical coherence tomography in detection of plaque lipid content: dual-imaging study with optical coherence tomography and near-infrared spectroscopy

Background Lipid-rich plaque covered by a thin fibrous cap (FC) has been identified as a frequent morphological substrate for the development of acute coronary syndrome. Optical coherence tomography (OCT) permits the identification and measurement of the FC. Near-infrared spectroscopy (NIRS) has been approved for detection of coronary lipids. Aims We aimed to assess the ability of detailed OCT analysis to identify coronary lipids, using NIRS as the reference method. Methods In total, 40 patients with acute coronary syndrome underwent imaging of a non-culprit lesion by both NIRS and OCT. For each segment, the NIRS-derived 4 mm segment with maximal lipid core burden index (maxLCBI4mm) was assessed. OCT analysis was performed using a semi-automated method including measurement of the fibrous cap thickness (FCT) of all detected fibroatheromas. Subsequent quantitative volumetric evaluation furnished FCT, FC surface area (FC SA), lipid arc, and FC (fibrous cap) volume data. OCT features of lipid plaques were compared with maxLCBI4mm. Predictors of maxLCBI4mm >400 was assessed by using univariable and multivariable analysis. Results OCT features (mean FCT, total FC SA, FC volume, maximal, mean, and total lipid arcs) strongly correlated with the maxLCBI4mm (p = 0.012 for the mean FCT, respectively p < 0.001 for all other aforementioned features). The strongest predictors of maxLCBI4mm >400 were the maximal (p = 0.002) and mean (p = 0.002) lipid arc, and total FC SA (p = 0.012). Conclusions We found a strong correlation between the OCT-derived features and NIRS findings. Detailed OCT analysis may be reliably used for detection of the presence of coronary lipids.

Preliminary study of the significance of reverberation by IVUS detection for patients with severe calcified lesions.

To explore the potential significance of the reverberation of calcification by comparing both intravascular ultrasound (IVUS) and optical coherence tomography (OCT) measurement post manual coregistration. The reverberation phenomenon is often detected by IVUS for severe calcified lesions post rotational atherectomy (RA), which is thought to be due to the glassy and smooth inner surfaces of calcifications. Because of the poor penetration of IVUS, it is impossible to measure the thickness of calcifications, and the relationship between multiple reverberations and the thickness of calcification lesions has not been reported before. A total of forty-nine patients with severe calcified coronary lesions that were detected by IVUS and OCT simultaneously were enrolled in our retrospective study. If reverberation phenomena were detected by IVUS, intravascular imaging (IVI) data (including distance between the IVUS catheter center and the inner surface of the reverberation signal, the intervals between all adjacent reverberation signals, the number of layers of reverberation in IVUS, and the thickness of the calcification in OCT) were measured at the same position and same direction (each cross-section had 4 mutually perpendicular directions) at 1-mm intervals. The correlation between each reverberation observational value and OCT data was the primary target in this retrospective study, and the correlation between reverberation and calcium crack post predilatation was analyzed in other 15 patients. Four hundred twenty-eight valid observational points were analyzed simultaneously by IVUS and OCT; among them, 300 points had a single layer of reverberation, 83 had double layers of reverberation and 42 had multiple layers (≥ 3 layers) of reverberation by IVUS detection post-RA. Multivariate logistic regression analysis showed that the number of layers of reverberation by IVUS was significantly related to the thickness of calcifications by OCT at the same point and in the same direction (p < 0.001). Single, double, and multiple layers of reverberation in IVUS correspond to median calcification thicknesses (interquartile ranges (IQRs)) of 0.620mm (0.520-0.720), 0.950mm (0.840-1.040) and 1.185mm (1.068-1.373), respectively, by OCT detection. Another 100 points in other 15 patients with integrated IVUS data pre- and post-predilatation showed that only single layer of reverberation was related to calcium crack (p < 0.001). The number of layers of reverberation signal detected by IVUS is positively correlated with the thickness of calcifications measured by OCT post-RA and single layer of reverberation is correlated to calcium crack post-predilatation.

Optical Coherence Tomography Angiography Compared With Optical Coherence Tomography for Detection of Early Glaucoma With High Myopia.

Purpose: To investigate the diagnostic abilities of the perfusion density (PD) and structural thickness parameters in the peripapillary and macular regions measured by optical coherence tomography angiography (OCTA) and optical coherence tomography (OCT) and to test if their diagnostic abilities of early glaucoma are different between highly myopic (HM) and non-highly myopic (NHM) patients.Methods: A total of 75 glaucoma patients and 65 controls were included in the analyses. The glaucoma detection abilities of macular PD and peripapillary PD, along with macular ganglion cell-inner plexiform layer (mGCIPL) thickness and peripapillary retinal nerve fiber layer (pRNFL) thicknesses were compared between the HM and NHM group. Diagnostic ability was assessed by area under the receiver operating characteristics (AUC) curves, adjusted by age, axial length, and signal strength.Results: The diagnostic ability of macular PD and mGCIPL thickness had no significant difference in both HM and NHM groups. However, the diagnostic ability of peripapillary PD except in the temporal section was significantly lower in the HM group than in the NHM group (all p < 0.05). The diagnostic ability of the superior, nasal, and average pRNFL thickness was also significantly lower in the HM group than in the NHM group (all p < 0.05).Conclusion: This study demonstrated that although peripapillary PD and macular PD were both significantly reduced in patients with highly myopia, the diagnostic ability of peripapillary PD in HM patients was significantly lower than that in NHM patients, while macular PD was not. Macular OCTA along with OCT imaging should be included in the imaging algorithm in early glaucoma diagnosis in highly myopic patients.

Extraction of phase-based optoretinograms (ORG) from serial B-scans acquired over tens of seconds by mouse retinal raster scanning OCT system.

Several specialized retinal optical coherence tomography (OCT) acquisition and processing methods have been recently developed to allow in vivo probing of light-evoked photoreceptors function, focusing on measurements in individual photoreceptors (rods and cones). Recent OCT investigations in humans and experimental animals have shown that the outer segments in dark-adapted rods and cones elongate in response to the visible optical stimuli that bleach fractions of their visual photopigment. We have previously successfully contributed to these developments by implementing OCT intensity-based "optoretinograms" (ORG), the paradigm of using near-infrared OCT (NIR OCT) to measure bleaching-induced back-scattering and/or elongation changes of photoreceptors in the eye in vivo. In parallel, several groups have successfully implemented phase-based ORGs, mainly in human studies, exploiting changes in the phases of back-scattered light. This allowed more sensitive observations of tiny alterations of photoreceptors structures. Applications of the phase-based ORG have been implemented primarily in high speed and cellular resolution AO-OCT systems that can visualize photoreceptor mosaic, allowing phase measurements of path length changes in outer segments of individual photoreceptors. The phase-based ORG in standard resolution OCT systems is much more demanding to implement and has not been explored extensively. This manuscript describes our efforts to implement a phase analysis framework to retinal images acquired with a standard resolution and raster scanning OCT system, which offers much lower phase stability than line-field or full-field OCT detection schemes due to the relatively slower acquisition speed. Our initial results showcase the successful extraction of phase-based ORG signal from the B-scans acquired at ∼100 Hz rate and its favorable comparison with intensity-based ORG signal extracted from the same data sets. We implemented the calculation of phase-based ORG signals using Knox-Thompson paths and modified signal recovery by adding decorrelation weights. The phase-sensitive ORG signal analysis developed here for mouse retinal raster scanning OCT systems could be in principle extended to clinical retinal raster scanning OCT systems, potentially opening doors for clinically friendly ORG probing.

Reader Response: Optical Coherence Tomography for Detection of Asymptomatic Optic Nerve Lesions in Clinically Isolated Syndrome.

The article of Outteryck et al.1 shows the importance of optical coherence tomography (OCT) for detection of optic neuritis lesions in patients with multiple sclerosis (MS), which adds to early diagnosis and better management, especially in the clinically isolated syndromes. It would also help in the research purpose for early intervention in patients with MS, as earliest intervention is best. The prognosis of multiple sclerosis is improving day by day, which requires the diagnosis at the earliest possible time as highlighted in the editorial by Villoslada et al.2 Likewise, OCT can also diagnose the foveal macular lesion differentiating MS from neuromyelitis optica spectrum disorders (NMOSDs).3 The diagnosis of MS is hampered by lack of adequate facilities and accessibility of MRI, oligoclonal bands (OCBs), and evoked potentials (EPs) in resource-poor areas, whereas the availability and accessibility of the ophthalmologists and OCTs is better and likely more cost-effective in comparison, which may result in better diagnosis, management, and follow-up for MS and NMOSD, as we see in day-to-day practice. OCT is more readily available in our setup than OCBs and is comparatively cheaper.

Editors' Note: Optical Coherence Tomography for Detection of Asymptomatic Optic Nerve Lesions in Clinically Isolated Syndrome

In the article “Optical Coherence Tomography for Detection of Asymptomatic Optic Nerve Lesions in Clinically Isolated Syndrome,” Dr. Outteryck et al. evaluated the ability of intereye retinal thickness difference (IETD) measured by optical coherence tomography (OCT) to detect asymptomatic optic nerve involvement in 130 patients who had presented with clinically isolated syndrome (CIS) within 4.5 months of enrollment. They found that detection of asymptomatic optic nerve lesions in CIS required lower ganglion cell–inner plexiform layer (GC-IPL) IETD thresholds than previously reported and concluded that GC-IPL IETD represents an alternative biomarker to MRI for the detection of such lesions. Although lowering the IETD thresholds may improve the sensitivity of detecting an optic nerve lesion, it comes at the expense of lowering the specificity and this will potentially increase the risk of a false diagnosis of an optic nerve lesion. In response, Dr. Shubhakaran suggests that such a biomarker could help in early intervention to improve the prognosis of patients with multiple sclerosis (MS) and also highlights the utility of OCT in diagnosing macular lesions that may differentiate MS from other disorders. Dr. Shubhakaran notes that OCT is more readily available in certain practice regions than MRI, oligoclonal band testing, and evoked potentials. Responding to these comments, Dr. Outteryck agrees with the utility of OCT in the evaluation of demyelinating diseases, and with the disparate accessibility to OCT and MRI in different parts of the world, but cautions that optic nerve involvement is still not part of the diagnostic criteria for MS for dissemination in space. Noting that optic nerve involvement in patients with CIS is associated with the presence of asymptomatic gadolinium enhancing lesions, Dr. Outteryck argues that optic nerve involvement should be accommodated in future iterations of the MS diagnostic criteria. This exchange illuminates the potential role that OCT can play in the evaluation of the optic nerves in patients with suspected demyelinating disease, even in the absence of ocular symptoms, and also highlights the enduring debate about how optic nerve involvement could be incorporated in the diagnostic criteria for MS. In the article “Optical Coherence Tomography for Detection of Asymptomatic Optic Nerve Lesions in Clinically Isolated Syndrome,” Dr. Outteryck et al. evaluated the ability of intereye retinal thickness difference (IETD) measured by optical coherence tomography (OCT) to detect asymptomatic optic nerve involvement in 130 patients who had presented with clinically isolated syndrome (CIS) within 4.5 months of enrollment. They found that detection of asymptomatic optic nerve lesions in CIS required lower ganglion cell–inner plexiform layer (GC-IPL) IETD thresholds than previously reported and concluded that GC-IPL IETD represents an alternative biomarker to MRI for the detection of such lesions. Although lowering the IETD thresholds may improve the sensitivity of detecting an optic nerve lesion, it comes at the expense of lowering the specificity and this will potentially increase the risk of a false diagnosis of an optic nerve lesion. In response, Dr. Shubhakaran suggests that such a biomarker could help in early intervention to improve the prognosis of patients with multiple sclerosis (MS) and also highlights the utility of OCT in diagnosing macular lesions that may differentiate MS from other disorders. Dr. Shubhakaran notes that OCT is more readily available in certain practice regions than MRI, oligoclonal band testing, and evoked potentials. Responding to these comments, Dr. Outteryck agrees with the utility of OCT in the evaluation of demyelinating diseases, and with the disparate accessibility to OCT and MRI in different parts of the world, but cautions that optic nerve involvement is still not part of the diagnostic criteria for MS for dissemination in space. Noting that optic nerve involvement in patients with CIS is associated with the presence of asymptomatic gadolinium enhancing lesions, Dr. Outteryck argues that optic nerve involvement should be accommodated in future iterations of the MS diagnostic criteria. This exchange illuminates the potential role that OCT can play in the evaluation of the optic nerves in patients with suspected demyelinating disease, even in the absence of ocular symptoms, and also highlights the enduring debate about how optic nerve involvement could be incorporated in the diagnostic criteria for MS.

Author Response: Optical Coherence Tomography for Detection of Asymptomatic Optic Nerve Lesions in Clinically Isolated Syndrome.

We thank Dr. Shubhakaran for his positive feedback on our article.1 Indeed, optical coherence tomography (OCT) is an interesting tool for imaging demyelinating CNS disorders. OCT enables clinicians to detect symptomatic optic nerve lesion at distance from the clinical episode, to detect asymptomatic optic nerve lesion(s) in clinically isolated syndrome (CIS),1 and relapsing-remitting multiple sclerosis (MS),2 and it may be of help to differentiate MS and neuromyelitis optica spectrum disorders.3 If the duration of OCT and 3D-DIR sequence (6 minutes) remains quite close, it is true that accessibility to 3T-MRI scanner and spectral-domain (SD)-OCT are not equal all over the world. Symptomatic (30%) and asymptomatic (30%) optic nerve involvement is frequent at the earliest clinical stage of MS,4 but the optic nerve is still not part of MS diagnosis criteria. Considering optic nerve involvement could be useful for demonstrating dissemination in space (fifth typical location) and time (new lesion). In addition, optic nerve involvement at CIS stage was found significantly associated with the presence of asymptomatic gadolinium-enhanced lesion.5 As with others, we are convinced by the necessity of optic nerve inclusion in the next version of MS diagnosis criteria. SD-OCT—which is more accessible than MRI—will improve diagnosis workup, management, and follow-up of patients affected by CNS demyelinating disorders.

Imaging-Based Uveitis Surveillance in Juvenile Idiopathic Arthritis: Feasibility, Acceptability, and Diagnostic Performance.

Children with juvenile idiopathic arthritis (JIA) need regular examinations for uveitis to avoid visual morbidity from the most common extraarticular manifestation of disease. This study was undertaken to investigate the feasibility, acceptability, and performance of optical coherence tomography (OCT) imaging-based diagnosis of uveitis. This observational cross-sectional study included children with and those without uveitis. The children underwent routine clinical examinations and anterior segment OCT scanning of intraocular inflammatory cells. Acceptability of image acquisition was assessed using a visual analog scale and length of time needed to acquire images. Interobserver and intraobserver variability of manual counting of acquired images (Bland-Altman limits of agreement), correlation between imaging and routine assessment, and sensitivity and specificity of anterior segment OCT detection of active inflammation were assessed. Of the 26 children ages 3-15 years (median age 8 years) who underwent imaging, 12 had active inflammation. All patients rated the acceptability of image acquisition as at least 8.5 on a scale of 0-10. Time taken to acquire images ranged from 1.5 minutes to 22 minutes (median time 8 minutes). There was good positive correlation between clinical assessment and image-based cell quantification (R2 = 0.63, P = 0.002). Sensitivity of anterior segment OCT manual image cell count for diagnosis of active inflammation was 92% (95% confidence interval [95% CI] 62-99%), specificity was 86% (95% CI 58-98%), and negative predictive value (ruling out uveitis) was 92% (95% CI 65-99%). Non-contact, high-resolution imaging for JIA uveitis surveillance is feasible, acceptable to patients, and holds the promise of transforming pediatric practice. Further work is needed to determine the analytic and clinical validity of anterior segment OCT quantification of active inflammation, and the clinical utility and cost-effectiveness of imaging-based disease monitoring.

Optical coherence tomography for detection of asymptomatic optic nerve lesions in clinically isolated syndrome

To evaluate the ability of intereye retinal thickness difference (IETD) measured by optical coherence tomography (OCT) to detect asymptomatic optic nerve involvement in clinically isolated syndrome (CIS). We conducted a cross-sectional study of patients who recently presented a CIS (≤4.5 months). All patients underwent OCT and brain/optic nerve MRI. Optic nerve involvement was defined clinically (episode of optic neuritis [ON] or not) and radiologically (optic nerve hypersignal on 3D double inversion recovery [3D-DIR]). We evaluated the sensitivity and specificity of previously published IETD thresholds and report the observed optimal thresholds for identifying symptomatic optic nerve involvement but also for identifying asymptomatic optic nerve involvement (optic nerve hypersignal without ON history). Primary outcomes were ganglion cell-inner plexiform layer (GC-IPL) and peripapillary retinal nerve fiber layer IETD. The study group consisted of 130 patients. In the CIS with ON group, 3D-DIR showed a hypersignal in all 41 symptomatic optic nerves and in 11 asymptomatic optic nerves. In the CIS without ON group, 3D-DIR showed a unilateral optic nerve hypersignal in 22 patients and a bilateral optic nerve hypersignal in 7 patients. For the detection of symptomatic and asymptomatic optic nerve lesion, GC-IPL IETD had better performance. We found an optimal GC-IPL IETD threshold ≥2.83 µm (sensitivity 88.2, specificity 83.3%) for the detection of symptomatic lesions and an optimal GC-IPL IETD ≥1.42 µm (sensitivity 89.3%, specificity 72.6%) for the detection of asymptomatic lesions. Detection of asymptomatic optic nerve lesions in CIS requires lower IETD thresholds than previously reported. GC-IPL IETD represents an alternative biomarker to MRI for the detection of asymptomatic optic nerve lesions. This study provides Class I evidence that OCT accurately identifies asymptomatic optic nerve involvement in patients with CIS.

Evaluating optical coherence tomography for surgical margin assessment of canine mammary tumours.

Optical coherence tomography (OCT) uses near-infrared light waves to generate real-time, high-resolution images on the microscopic scale similar to low power histopathology. Previous studies have demonstrated the use of OCT for real-time surgical margin assessment for human breast cancer. The use of OCT for canine mammary tumours (CMT) could allow intra-operative visualisation of residual tumour at the surgical margins. The purpose of this study was to assess OCT imaging for the detection of incomplete tumour resection following CMT surgery. We hypothesized that the OCT images would have comparable features to histopathological images of tissues at the surgical margins of CMT resections along with a high sensitivity of OCT detection of incomplete surgical excision of CMT. Thirty surgical specimens were obtained from nineteen client-owned dogs undergoing surgical resection of CMT. OCT image appearance and characteristics of adipose tissue, skin, mammary tissue and mammary tumour at the surgical margins were distinct and different. The OCT images of normal and abnormal tissues at the surgical margins were utilized to develop a dataset of OCT images for observer evaluation. The sensitivity and specificity for ex vivo images were 83.3% and 82.0% (observer 1) and 70.0% and 67.9% (observer 2). The sensitivity and specificity for in vivo images were 70.0% and 89.3% (observer 1) and 76.7% and 67.9% (observer 2). These results indicate a potential use of OCT for surgical margin assessment for CMT to optimize surgical intervention and clinical outcomes. Improved training and experience of observers may improve sensitivity and specificity.

Early Detection of Diabetic Retinopathy Using PCA-Firefly Based Deep Learning Model

Diabetic Retinopathy is a major cause of vision loss and blindness affecting millions of people across the globe. Although there are established screening methods - fluorescein angiography and optical coherence tomography for detection of the disease but in majority of the cases, the patients remain ignorant and fail to undertake such tests at an appropriate time. The early detection of the disease plays an extremely important role in preventing vision loss which is the consequence of diabetes mellitus remaining untreated among patients for a prolonged time period. Various machine learning and deep learning approaches have been implemented on diabetic retinopathy dataset for classification and prediction of the disease but majority of them have neglected the aspect of data pre-processing and dimensionality reduction, leading to biased results. The dataset used in the present study is a diabetes retinopathy dataset collected from the UCI machine learning repository. At its inceptions, the raw dataset is normalized using the Standardscalar technique and then Principal Component Analysis (PCA) is used to extract the most significant features in the dataset. Further, Firefly algorithm is implemented for dimensionality reduction. This reduced dataset is fed into a Deep Neural Network Model for classification. The results generated from the model is evaluated against the prevalent machine learning models and the results justify the superiority of the proposed model in terms of Accuracy, Precision, Recall, Sensitivity and Specificity.

Application of optical coherence tomography in clinical diagnosis.

BACKGROUND:Optical coherence tomography (OCT) is a non-invasive diagnosing tool used in clinics. Due to its high resolution (<10um), it is appropriate for the early detection of tiny infections. It has been widely used in diagnosis and treatment of diseases, evaluation of therapeutic efficacy, and monitoring of various physiological and pathological processes.OBJECTIVE:To systemically review literature to summarize the clinic application of OCT in recent years.METHODS:For clinic applications that OCT has been applied, we selected studies that describe the most relevant works. The discussion included: 1) which tissue could be used in the OCT detection, 2) which character of different tissue could be used as diagnosing criteria, 3) which diseases and pathological process have been diagnosed or monitored using OCT imaging, and 4) the recent development of clinic OCT diagnosing.RESULTS:The literature showed that the OCT had been listed as a routine test choice for ophthalmic diseases, while the first commercial product for cardiovascular OCT detection had gotten clearance. Meanwhile, as the development of commercial benchtop OCT equipment and tiny fiber probe, the commercial application of OCT in dermatology, dentistry, gastroenterology and urology also had great potential in the near future.CONCLUSIONS:The analysis and discussions showed that OCT, as an optical diagnosing method, has been used successfully in many clinical fields, and has the potential to be a standard inspection method in several clinic fields, such as dermatology, dentistry and cardiovascular.

Impact of velocity gradient in Poiseuille flow on the statistics of coherent radiation scattered by flowing Brownian particles in optical coherence tomography.

.A closed-form expression is obtained for the temporal correlation function of the scattered radiation detected in optical coherence tomography (OCT), taking into account the flow velocity gradient across the OCT detection volume in the suspension of flowing Brownian particles. The analytical approach we use includes both the laser beam and wavefront curvature radii changing over the depth. Also, we compare our results with a previously obtained theoretical model, partially an empirical approach. Our findings suggest the importance of the flow velocity gradient for accurate measurements of flow velocity vector, particle diffusivity, shear-induced diffusion, and potentially other OCT applications.

Edge detection of retinal OCT image based on complex shearlet transform

Aiming at the problem that optical coherence tomography (OCT) images with low contrast and layer structure blur are difficult to be automatically layered, a new OCT detection method based on complex shearlet transform is proposed. The method utilises nearly optimal sparse approximation singular curves of multi-scale shearlet transform, and the contrast invariance of the phase congruence method. Compared with the Canny edge detector and wavelet methods, the complex shearlet-based method achieved the highest Pratt figure of merit (PFOM) value. The PFOM value of a step type edge is 0.92, and that of a pulse type edge is 0.98. Three types of OCT images were tested, including normal retinal macula area, dry age-related macular degeneration, and Stargardt disease. The experimental results show that the complex shearlet-based method can detect more layered structures of OCT images, especially the boundary between the ganglion cell layer and the inner plexiform layer that is difficult to detect, and it can detect various types of OCT images. The complex shearlet-based transform method provides an effective and general way to measure retinal OCT images.

Therapeutic Effect of Traditional Chinese Medicine on a Rat Model of Branch Retinal Vein Occlusion.

Branch retinal vein occlusion (BRVO) is a common retinal vascular disorder leading to visual impairment. Currently, the general strategies for BRVO are symptomatic therapies. Cardiovascular aspects are essential risk factors for BRVO. The traditional Chinese medicine hexuemingmu (HXMM), consisting of tanshinol and baicalin, dilates the vasculature and accelerates microcirculation. Therefore, the aim of this study was to determine the efficacy and possible mechanism of HXMM in a BRVO rat model established by laser photocoagulation. Successful BRVO rat models were treated with different doses of HXMM. Fundus photography and fluorescein fundus angiography (FFA) of the animals were applied. The retinal layers were measured by optical coherence tomography (OCT). Full-field electroretinography (ffERG) was applied to evaluate the retinal function. The ear vein flow velocity was measured via a microcirculation detector. The expression of the vascular endothelial growth factor (VEGF-α) was measured via western blotting and immunofluorescent staining. Our study found that retinal edema predominantly occurred in the inner nuclear layer (INL) and outer nuclear layer (ONL). The retinal edema of the treated groups was significantly relieved in the early stage of BRVO as visualized via OCT detection and HE staining. The amplitudes of the b wave and oscillatory potentials (OPs) waves of ffERG in the treated groups were increased compared with those of the control group at several detection points (3, 5, 7, 10, 14, and 21 d postocclusion). The expression of VEGF-α was reduced in the treated groups at an early stage of BRVO. Furthermore, the ear vein flow velocity of the HXMM treatment groups was faster than that of the control group. Thus, our study indicates that the traditional Chinese medicine HXMM could ameliorate retinal edema and rescue the retinal structure and function in BRVO models through promoting occluded vein recanalization, improving microcirculation, and regulating the expression of VEGF-α.

Needle-based optical coherence tomography for the detection of prostate cancer: a visual and quantitative analysis in 20 patients.

Diagnostic accuracy of needle-based optical coherence tomography (OCT) for prostate cancer detection by visual and quantitative analysis is defined. 106 three-dimensional (3-D)-OCT data sets were acquired in 20 prostates after radical prostatectomy and precisely matched with pathology. OCT images were grouped per histological category. Two reviewers performed blind assessments of the OCT images. Sensitivity and specificity for malignancy detection were calculated. Quantitative analyses by automated optical attenuation coefficient calculation were performed. OCT can reliably differentiate between fat, cystic, and regular atrophy and benign glands. The overall sensitivity and specificity for malignancy detection was 79% and 88% for reviewer 1 and 88% and 81% for reviewer 2. Quantitative analysis for differentiation between stroma and malignancy showed a significant difference (4.6 mm - 1 versus 5.0 mm - 1 Mann-Whitney U-test p < 0.0001). A Kruskal-Wallis test showed a significant difference in median attenuation coefficient between stroma, inflammation, Gleason 3, and Gleason 4 (4.6, 4.1, 5.9, and 5.0 mm - 1, respectively). However, attenuation coefficient varied per patient and a related-samples Wilcoxon signed-rank test showed no significant difference per patient (p = 0.17). This study confirmed the one to one correlation of histopathology and OCT. Precise matching showed that most histological tissues categories in the prostate could be distinguished by their unique pattern in OCT images. In addition, the optical attenuation coefficient can play a role in the differentiation between stroma and malignancy; however, a per patient analysis of the optical attenuation coefficient did not show a significant difference.

Analysis of peripapillary retinal nerve fiber layer and inner macular layers by spectral-domain optical coherence tomography for detection of early glaucoma

To analyze the diagnostic capabilities of peripapillary retinal nerve fiber layer (pRNFL) thickness and segmented inner macular layer (IML) thickness measured by spectral-domain optical coherence tomography for detection of early glaucoma. Fifty-three patients with primary open angle glaucoma (POAG), 60 patients with normal tension glaucoma (NTG) and 32 normal control subjects were enrolled. Thicknesses of pRNFL, total macular layers (TML), and the IML, including macular RNFL (mRNFL) and macular ganglion cell layer (mGCL) were assessed. The areas under the receiver operating characteristic curves (AROC) were calculated to compare the diagnostic power of different parameters. There were no differences in the parameters of pRNFL, TML, and IML between POAG and NTG groups. The thicknesses of superior and inferior mGCL showed significant correlation with mean deviation of visual field (R2=0.071, P=0.004; R2=0.08, P=0.002). The mGCL thickness significantly correlated with the pRNFL thickness in the superior and inferior quadrants (R2=0.156, P<0.001; R2=0.407, P<0.001). The thickness of the inferior-outer sector of macula had greater AROCs than those in the inferior-inner sector of macula. The AROCs for superior (0.894) and inferior (0.879) pRNFL thicknesses were similar with the AROCs for superior (0.839) and inferior mGCL (0.864) thicknesses. Sensitivities at 80% specificity for global pRNFL, inferior-outer mGCL and inferior-outer mRNFL thicknesses were 0.938, 0.867, and 0.725, respectively. The diagnostic capability of the mGCL thickness is comparable to that of the pRNFL thickness in patients with early glaucoma. The inferior-outer sector of IML has a better diagnostic capability than the inferior-inner sector of IML for detection of early glaucoma.

220 A Stereotactic Brain Biopsy Needle Integrating an Optical Coherence Tomography (OCT) Probe with Blood Vessel Detection in Human Patients

Abstract INTRODUCTION Stereotactic brain biopsies are a common neurosurgical procedure used predominantly to obtain histological diagnosis of brain pathologies. Intracranial haemorrhage is the most frequent complication related to this procedure and is associated with increased morbidity and mortality. We present a pilot study investigating a customised miniature Optical Coherence Tomography (OCT) probe integrated into a commercial stereotactic brain biopsy needle. OCT is a high-resolution optical imaging modality that uses reflections of low-power, near-infrared light to characterise tissue. The probe is combined with fully automated blood vessel detection software based on speckle decorrelation to provide real-time feedback as the needle tip encounters a blood vessel. METHODS We demonstrate the use of such a needle intraoperatively for the first time in humans. A total of 167 superficial blood vessel and control measurements were obtained in 11 patients undergoing craniotomies for various pathologies. Deep blood vessel measurements were also acquired in 3 patients. Superficial blood vessel measurements were obtained by directly placing the probe over cortical vessels exposed during craniotomy and validated against intraoperative photographs. Deep vessels were targeted using preoperative MRI and frameless stereotactic surgical navigation. RESULTS &gt;For the superficial vessel measurements, the probe demonstrated a sensitivity of &gt;88% and specificity &gt;98% for the detection of blood vessels &gt;500microns in diameter. For the deep vessel measurements, the probe was able to detect a blood vessel appropriately on all three occasions. CONCLUSION This pioneering study demonstrates OCT detection of blood vessels in human patients in real-time, integrated with current Neurosurgical practices. This work opens the possibilities of further studies using OCT to detect blood vessels in probe based Neurosurgery to minimise the risk of haemorrhage from such procedures.

Diagnostic Ability of Wide-field Retinal Nerve Fiber Layer Maps Using Swept-Source Optical Coherence Tomography for Detection of Preperimetric and Early Perimetric Glaucoma.

To evaluate the diagnostic ability of wide-field retinal nerve fiber layer (RNFL) maps with swept-source optical coherence tomography (SS-OCT) for detection of preperimetric (PPG) and early perimetric glaucoma (EG). One hundred eighty-four eyes, including 67 healthy eyes, 43 eyes with PPG, and 74 eyes with EG, were analyzed. Patients underwent a comprehensive ocular examination including red-free RNFL photography, visual field testing and wide-field SS-OCT scanning (DRI-OCT-1 Atlantis; Topcon, Tokyo, Japan). SS-OCT provides a wide-field RNFL thickness map and a SuperPixel map, which are composed of the RNFL deviation map of the peripapillary area and the deviation map of the composition of the ganglion cell layer with the inner plexiform layer and RNFL (GC-IPL+RNFL) in the macular area. The ability to discriminate PPG and EG from healthy eyes was assessed using sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) for all parameters and criteria provided by the wide-field SS-OCT scan. The wide-field RNFL thickness map using SS-OCT showed the highest sensitivity of PPG-diagnostic and EG-diagnostic performance compared with the other SS-OCT criteria based on the internal normative base (93.0 and 97.3%, respectively). Among the SS-OCT continuous parameters, the RFNL thickness of the 7 clock-hour, inferior and inferotemporal macular ganglion cell analyses showed the largest AUC of PPG-diagnostic and EG-diagnostic performance (AUC=0.809 to 0.865). The wide-field RNFL thickness map using SS-OCT performed well in distinguishing eyes with PPG and EG from healthy eyes. In the clinical setting, wide-field RNFL maps of SS-OCT can be useful tools for detection of early-stage glaucoma.