Automatic Choroid Vascularity Index Calculation in Optical Coherence Tomography Images Low Contrast Sclerochoroidal Junction Using Deep Learning

Choroidal vascularity index (CVI) is a new biomarker defined for retinal optical coherence tomography (OCT) images for measuring and evaluating the choroidal vascular structure. CVI is the ratio of the choroidal luminal area (LA) to the total choroidal area (TCA). The automatic calculation of this index is important for ophthalmologists but has not yet been explored. In this study, we proposed a fully automated method based on deep learning for calculating CVI in three main steps: 1- segmentation of the choroidal boundary, 2- detection of the choroidal luminal vessels, and 3- computation of the CVI. The proposed method is evaluated in complex situations like the presence of diabetic retinopathy and pachychoroid spectrum. In pachychoroid spectrum, the choroid is thickened, and the boundary between choroid and sclera (sclerochoroidal junction) is blurred, which makes the segmentation more challenging. The proposed method is designed based on the U-Net model, and a new loss function is proposed to overcome the segmentation problems. The vascular LA is then calculated using Niblack’s local thresholding method, and the CVI value is finally computed. The experimental results for the segmentation stage with the best-performing model and the proposed loss function were used showed dice coefficients of 0.941 and 0.936 in diabetic retinopathy and pachychoroid spectrum patients, respectively. The unsigned boundary localization errors in the presence of diabetic retinopathy were 0.0020 and 0.0138 pixels for the BM boundary and sclerochoroidal junction, respectively. Similarly, the unsigned errors in the presence of pachychoroid spectrum were 0.0072 and 0.0254 pixels for BM and sclerochoroidal junction. The performance of the proposed method for calculating CVI was evaluated; the Bland-Altman plot indicated acceptable agreement between the values allocated by experts and the proposed method in the presence of diabetic retinopathy and pachychoroid spectrum.

Testicular effects of a postnatal GnRH antagonist in domestic cats

The aim of this study was to describe the histological effects of two high postnatal doses of the potent third-generation GnRH antagonist, acyline in the domestic cat testicle. Secondly, the physical, endocrine, and steroidogenic findings of this pharmaceutical protocol are also reported. Twelve postnatal littermate male kittens were administered acyline in a dose of 2.2 mg/100 g SC weekly for 2 weeks (ACY; n = 6), or placebo (PL; n = 6). All the animals were followed up until puberty when they were castrated. Serial faecal samples were collected until the age of 10 weeks for testosterone (T) measurement. The kittens achieved puberty without either age (236.5 ± 19.7 vs. 221.7 ± 23.7 days) or body weight (3.05 ± 0.15 vs. 2.78 ± 0.28 kg, P > 0.05) differences between ACY and PL, respectively. Acyline suppressed faecal T concentrations for 3 weeks (P < 0.01). From the fourth week on, both groups had low concentrations up to the end of the follow-up period (P > 0.05). Histological assessment of the testes showed that ACY cats presented a reduced height of the epithelium (P < 0.01) due to the diminished number of germinal cells accompanied by an enlarged luminal area (P < 0.01) with cellular debris (P < 0.01). The immunostaining of P450c17 also appeared partially diminished in ACY testes.

Investigation of the pathophysiology of the retina and choroid in Parkinson's disease by optical coherence tomography

Purpose The pathology of Parkinson's disease (PD) is suspected to affect the retina and choroid. We investigated changes in the retina and choroid of patients with PD using optical coherence tomography. Methods We examined 14 patients with PD and 22 patients without PD. Patients without PD had no ophthalmic disease other than cataracts. In addition, it was also confirmed that there was no neurodegenerative disease. The retinal nerve fiber layer, ganglion cell layer + inner plexiform layer, and choroidal thickness were compared between both groups. Additionally, the choroidal image was divided into the choroid area, luminal area, and interstitial area using the binarization method, and the area of each region and the percentage of luminal area in the choroid area were analyzed. Results Patients with PD had a significantly thinner ganglion cell layer + inner plexiform layer compared to those without PD. The choroid area, luminal area, and interstitial area were significantly decreased in patients with PD compared to those without PD. Seven patients with PD who were successfully followed up showed decreased retinal nerve fiber layer and interstitial area after 3 years. Conclusion Autonomic nervous disorders and neurodegeneration in PD can cause thinning of the retina and choroid, as well as a reduction in the choroid area.

Assessment of choroidal vascularity index during the menstrual cycle

Purpose To explore the effect of menstrual cycle on choroidal vascularity index (CVI). Methods Thirty six eyes of 36 healthy women were included in this prospective study. The menstrual cycles were regular and ranged from 28 to 30 days in length. Optical coherence tomography images were obtained in 3 different phases of the menstrual cycle. The choroidal thickness (CT), total choroidal area, luminal area, stromal area, and CVI were quantified. Results Mean subfoveal, nasal and temporal CT were significantly changed in mid-luteal phase in comparison to early follicular (p = 0.018, p = 0.006 and p = 0.001, respectively) and ovulatory phases (p = 0.037, p = 0.037, and p = 0.035, respectively). Mean CVI showed a significant change in mid-luteal phase when compared with early follicular (p = 0.001) and ovulatory phases (p = 0.036). Conclusion CVI seemed to be affected in mid-luteal phase of menstrual cycle. This should be considered while analyzing choroidal structure in otherwise healthy women.

Choroidal Vascularity Index in Adult-Onset Foveomacular Vitelliform Dystrophy: A Pilot Study

This pilot study aims to investigate choroidal vascular status in eyes with adult-onset foveomacular vitelliform dystrophy (AOFVD), early age-related macular degeneration (AMD), and age-matched controls. In this retrospective study, choroidal thickness (CT) was measured manually using spectral domain optical coherence tomography images of the fovea, and 500 and 1500 µm from the nasal and temporal regions in the fovea. The horizontal B-scan was imported into Fiji software. Choroidal vascularity index (CVI) and luminal and stromal areas were calculated. A total of 36 eyes from 36 patients, including 18 eyes with AOFVD and 18 eyes with CD, and 16 eyes of healthy subjects were included. CVI was significantly different among subgroups (ANOVA, p = 0.004). Eyes with AOFVD presented a higher CVI (+0.03 ± 0.01, p = 0.001) than eyes with CD and controls (p = 0.03). No differences in CVI were detected between controls and eyes with CD (p = 0.25). AOFVD eyes accounted for the greatest luminal area, particularly significant in comparison with healthy controls (+0.27 ± 0.11, p = 0.02). AOFVD eyes present a greater CVI than eyes with CD and controls. The major choroidal involvement is on the luminal component, further corroborating a possible role of the choroidal vasculature in the pathological manifestations of AOFVD disease.

Airway luminal area and the resistive work of breathing during exercise in healthy young females and males

We examined the relationship between the work of breathing (Wb) during exercise and in vivo measures of airway size in healthy females and males. We hypothesized that sex-differences in airway luminal area (Ai) would explain the larger resistive Wb during exercise in females. Healthy participants (n=11 females and n=11 males; 19-30 y) completed a cycle exercise test to exhaustion where Wb was assessed using an esophageal balloon catheter. On a separate day, participants underwent a bronchoscopy procedure for optical coherence tomography measures of airways in the left (n=3) and right (n=4) lung. In vivo measures of Ai were made for the 4th-8th airway generations. A composite index of airway size was calculated as the sum of the Ai for each generation and the total area was calculated based on Weibel's model. We found that index of airway size (males: 37.4±6.3 mm2 vs. females: 27.5±7.4 mm2) and airway area calculated based on Weibel's model (males: 2274±557 mm2 vs. females: 1594±389 mm2) were significantly larger in males (both p=0.003). When minute ventilation was greater than ~60 l·min-1, the resistive Wb was higher in females. At the highest equivalent flow achieved by all subjects, resistance to inspired flow was larger in females and significantly associated with two measures of airway size: index of airway size (r=0.559, p=0.007) and Weibel area (r=0.541, p=0.009). Our findings suggest that innate sex-differences in Ai result in a greater resistive Wb during exercise in females compared to males.

Choroidal remodeling distribution pattern in the macular region in Chinese young patients with myopia

Background The pathogenesis of myopia has been found to be associated with the blood supply of the choroid. This study aimed to determine the relationship between the distribution pattern of choroidal remodeling and the degree of myopia in young patients. Methods Young patients (age < 18 years) with the spherical equivalent of less than − 12 diopters (D) were included. Spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging (EDI) modality was used to measure the choroidal thickness (CT) and choroidal vascularity index (CVI) in the macular regions. CVI was calculated as the proportion of luminal area to choroidal area and was measured within 1 mm and 3 mm nasal (N1 and N3), temporal (T1 and T3), superior (S1 and S3), and inferior (I1 and I3) to the foveal center. CVI was compared across different ages (i.e., 5 ~ 9 years, 10 ~ 13 years, and 14 ~ 18 years), axial lengths (ALs) (i.e., 21.00 ~ 25.00 mm and 25.01 ~ 29.00 mm), and spherical equivalents (SEs) (i.e., SE > -0.5D, − 0.5 ~ − 3.0D, − 3.01 ~ − 6.0D, and < − 6.0D). Linear regression analysis was applied to assess the association between independent (i.e., age, AL, SE, and intraocular pressure) and dependent variables (i.e., CVI of different regions). Results One hundred sixty-four eyes from 85 volunteers were included. The mean CT in the central foveal was 269.87 ± 63.32 μm (93.00 μm to 443.00 μm). The mean subfoveal-CVI was 67.66 ± 2.40% (57.84 to 79.60%). Multiple linear regression results revealed significant correlations between SE and T1-CVI (p < 0.05, r2 = 0.082, β = 0.194), N1-CVI (p < 0.05, r2 = 0.039, β = 0.212). Simple linear regression results revealed that T1-CVI (p < 0.05, r2 = 0.09) and T3-CVI (p < 0.05, r2 = 0.05) were negatively correlated with SE; N1-CVI (p < 0.05, r2 = 0.05) and N3-CVI (p < 0.05, r2 = 0.04) were negatively correlated with SE. Conclusions CVI in the horizontal meridian underwent the largest change as myopia worsened. Temporal and nasal CVIs within the r = 1 mm, and r = 3 mm subfoveal range were positively associated with the degree of myopia in young patients. The CVI value may be used to assess the vascular status of the choroid and be a potential marker of myopic progression.

Blood Pressure Models for Wearable Sensors

<div>As cardiovascular diseases are one of the most prominent illnesses, a continuous, non-invasive, and comfortable monitoring of blood pressure (BP) is indispensable. This paper investigates the best method for obtaining highly accurate BP values in non-invasive measurements when using an ultrasound (US) sensor projected for a wrist-worn device. State-of-the-art BP models were analyzed and qualitatively compared. Relevant arterial parameters such as luminal area, flow velocity and pulse wave velocity, of 729 subjects were extracted from a computer simulated database and served as input parameters for the wearable US. A linear in-silico model calibrated to each arterial-site revealed to be most accurate model. The linear model was used for the extraction of BP by using the US sensor and validated with a commercial pressure sensor in an ex-vivo experimental setup. The results showed an in-silico pulse pressure correlation of 0.978 and mean difference of (-2.134±2.477) mmHg at the radial artery and ex-vivo pressure correlation of 0.994 and mean difference of (0.554 ± 2.315) mmHg. Thus, with the linear model, the US measurement complies with the Association for the Advancement of Medical Instrumentation standard with deviations lower than 5 mmHg.</div>

Choroidal structural changes determined by the binarization method after intravitreal aflibercept treatment in neovascular age-related macular degeneration

AIM: To assess the choroidal structural alterations after intravitreal injection of aflibercept in neovascular age-related macular degeneration (nAMD). METHODS: Fifty eyes with treatment-naïve nAMD were evaluated at baseline, 3rd, and 12th month. Fifty eyes of 50 healthy subjects were also included as controls. Choroidal thickness (CT) was measured in the subfoveal region. Total circumscribed choroidal area (CA), luminal area (LA), stromal area (SA), and choroidal vascularity index (CVI) was calculated using Image J. RESULTS: At baseline, subfoveal CT was increased in nAMD patients compared to controls (P=0.321). Eyes with nAMD had a significantly increased total circumscribed CA and SA (P=0.041, 0.005, respectively). The CVI was decreased (P=0.038). In the 3rd month, the subfoveal CT, LA, and CVI revealed a decrease (P=0.005, P=0.039, 0.043, respectively). In the 12th month, subfoveal CT, LA, and CVI were decreased in comparison to baseline measures (P<0.001, 0.006, 0.010, respectively). CONCLUSION: Significant structural alterations are found after intravitreal aflibercept treatment during the 12-month follow-up, in particular at the third month, in eyes with nAMD.

Correlation of The Characteristics of Symptomatic Intracranial Atherosclerotic Plaques with Stroke Types and Risk of Stroke Recurrence

Purpose To explore the relationship of the characteristics of symptomatic intracranial atherosclerotic plaques (ICAP) with stroke types and risk of stroke recurrence. Methods Patients with symptomatic intracranial atherosclerotic stenosis were prospectively enrolled. The vessel stenosis degree, plaque shape, plaque thickness, plaque burden, and plaque enhancement degree of all patients were assessed using high-resolution magnetic resonance imaging and statistically analyzed. Results In total, 206 patients (mean age (64 ± 12) years; 141 males) were included in this study, 154 had acute ischemic stroke (AIS), 52 had transient ischemic attack (TIA), 124 had anterior circulation ischemic symptom (ACIS), and 82 had posterior circulation ischemic symptom (PCIS). AIS patients showed higher diastolic blood pressure (t=-2.605, p = 0.011), total cholesterol (t=-2.470, p = 0.014), apolipoprotein b (z=-2.411, p = 0.016), apolipoprotein a/b (t=-2.865, p = 0.006), LDL (t=-2.424, p = 0.016), arteriosclerosis index (z=-2.256, p = 0.024), stenosis degree (t=-3.317, p < 0.001) but smaller luminal area at the plaque than TIA patients (t = 2.539, p = 0.013). In addition, 24 (13.6%) patients had stroke recurrence within 6 months. The proportion of patients with T1WI hyperintensity was higher in patients with recurrent stroke than in patients without recurrent stroke (RR = 2.592 (1.091, 6.58), χ²=4.892, p = 0.034). Patients with PCIS had greater plaque thickness (t=-4.205, p < 0.001) and remaining luminal area (z=-4.127, p < 0.001), significantly enhanced ICAP (χ²=9.681, p = 0.003), more positive remodeling (χ²=5.661, p = 0.015) and higher incidence of T1WI hyperintensity (χ²=16.472, p < 0.001) than patients with ACIS. The prevalence of diabetes (χ²=9.038, p = 0.004) in patients with PCIS is higher than that in patients with ACIS. Conclusions The degree of stenosis and the remaining luminal area of symptomatic ICAP are related to the type of stroke, and patients with T1WI hyperintense plaque had a higher risk of stroke recurrence within six months. Posterior circulation culprit plaque tends to have higher vulnerability, which may be related to metabolic factors secondary to diabetes.