Automated Segmentation Analysis Research Articles

Muscarinic acetylcholine receptors M2 are upregulated in the atrioventricular nodal tract in horses with a high burden of second-degree atrioventricular block.

Second-degree atrioventricular (AV) block at rest is very common in horses. The underlying molecular mechanisms are unexplored, but commonly attributed to high vagal tone. To assess whether AV block in horses is due to altered expression of the effectors of vagal signalling in the AV node, with specific emphasis on the muscarinic acetylcholine receptor (M2) and the G protein-gated inwardly rectifying K+ (GIRK4) channel that mediates the cardiac IK,ACh current. Eighteen horses with a low burden of second-degree AV block (median 8 block per 20 h, IQR: 32 per 20 h) were assigned to the control group, while 17 horses with a high burden of second-degree AV block (median: 408 block per 20 h, IQR: 1,436 per 20 h) were assigned to the AV block group. Radiotelemetry ECG recordings were performed to assess PR interval and incidence of second-degree AV block episodes at baseline and on pharmacological blockade of the autonomic nervous system (ANS). Wenckebach cycle length was measured by intracardiac pacing (n = 16). Furthermore, the expression levels of the M2 receptor and the GIRK4 subunit of the IKACh channel were quantified in biopsies from the right atrium, the AV node and right ventricle using immunohistochemistry and machine learning-based automated segmentation analysis (n = 9 + 9). The AV block group had a significantly longer PR interval (mean ± SD, 0.40 ± 0.05 s; p < 0.001) and a longer Wenckebach cycle length (mean ± SD, 995 ± 86 ms; p = 0.007) at baseline. After blocking the ANS, all second-degree AV block episodes were abolished, and the difference in PR interval disappered (p = 0.80). The AV block group had significantly higher expression of the M2 receptor (p = 0.02), but not the GIRK4 (p = 0.25) in the AV node compared to the control group. Both M2 and GIRK4 were highly expressed in the AV node and less expressed in the atria and the ventricles. Here, we demonstrate the involvement of the m2R-IK,ACh pathway in underlying second-degree AV block in horses. The high expression level of the M2 receptor may be responsible for the high burden of second-degree AV blocks seen in some horses.

Brain atrophy in middle age using magnetic resonance imaging scans from Japan's health screening programme.

Although health screening plays a key role in the management of chronic diseases associated with lifestyle choices, brain health is not generally monitored, remaining a black box prior to the manifestation of clinical symptoms. Japan is unique in this regard, as brain MRI scans have been widely performed for more than two decades as part of Brain Dock, a comprehensive health screening programme. A vast number of stored images (well over a million) of longitudinal scans and extensive health data are available, offering a valuable resource for investigating the prevalence of various types of brain-related health conditions occurring throughout adulthood.In this paper, we report on the findings of our preliminary quantitative analysis of T1-weighted MRIs of the brain obtained from 13 980 subjects from three participating sites during the period 2015–19. We applied automated segmentation analysis and observed age-dependent volume loss of various brain structures. We subsequently investigated the effects of scan protocols and the feasibility of calibration for pooling the data. Last, the degree of brain atrophy was correlated with four known risk factors of dementia; blood glucose level, hypertension, obesity, and alcohol consumption.In this initial analysis, we identified brain ventricular volume as an effective marker of age-dependent brain atrophy, being highly sensitive to ageing and evidencing strong robustness against protocol variability. We established the normal range of ventricular volumes at each age, which is an essential first step for establishing criteria used to interpret data obtained for individual participants. We identified a subgroup of individuals at midlife with ventricles that substantially exceeded the average size. The correlation studies revealed that all four risk factors were associated with greater ventricular volumes at midlife, some of which reached highly significant sizes.This study demonstrates the feasibility of conducting a large-scale quantitative analysis of existing Brain Dock data in Japan. It will importantly guide future efforts to investigate the prevalence of large ventricles at midlife and the potential reduction of this prevalence, and hence of dementia risk, through lifestyle changes.

Automated segmentation analysis of 3DUS placental volumes yields an early biomarker of fetal growth potential

Placental volume (PV), obtained by 3D ultrasound (3DUS) as early as the first trimester, have been associated with fetal growth outcomes, such as small for gestational age and macrosomia. However, significant, manual post-processing is generally required to obtain a volume measure, limiting the potential for PV to serve a clinical role. Recently, we have developed and validated an automated segmentation algorithm, based on convolutional neural networks that can calculate PV without any manual input. Herein, we sought to determine if automated early PV measures are associated with birthweight and neonatal anthropometric measures of fat deposition. In this prospective cohort, 3DUS volume sets of the placenta were obtained at 11-16 weeks gestation and followed to delivery. Neonatal birth weight (BW) and centile (BW%) were recorded. When feasible, trained research staff obtained neonatal length (BL), head (HC), abdominal (AC), right upper mid arm (RAC) circumferences within 48 hours of birth. 3DUS volumes were processed using the automated segmentation algorithm to yield a PV measure, which was then normalized to gestational age (PVGA). Data was analyzed to determine any associations between PV and PVGA with neonatal measures. 96 singleton pregnancies were included with a mean PV of 91.6 (SD:28.8) cc obtained at a mean GA of 13.9 (1.04) wks. Mean GA at delivery was 38.7(1.6) wks with mean BW of 3122 (528) gm. PV and PVGA were both significantly correlated with BW and BW%. 52 subjects underwent neonatal anthropometry. PV and PVGA were significantly correlated with neonatal BL, HC, and RAC. Table. This study demonstrates that an automated segmentation tool that estimated early placental volume can yield an early biomarker of fetal growth potential. Despite numerous large studies aimed at customizing fetal growth curves, there remains no universally validated tool. An automated tool that delivers an early biomarker of an individual fetus’ growth potential has the potential for achieving a precision medicine approach for monitoring fetal growth and guiding surveillance.

Independent effects of white matter hyperintensities on frailty among individuals with Alzheimer's disease

AbstractBackgroundWith an aging global population, recent years have seen rapid expansion in the attention of the frailty. Thus, understanding, and determinant the potentially modifiable risk factor for frailty is a major concern for health care policy and provision.MethodSubjects were recruited for the study from the dementia clinic of Jeju National University Hospital between January 2018 and January 2020. All of the subjects were evaluated by using CERAD‐K and diagnosed probable AD and possible AD by a panel of two experienced dementia research neuropsychiatrists. WMH volume was calculated using automated segmentation analysis and further partitioned into three categories (Kim, BIOL PSYCHIATRY 2008). Frailty evaluated by Korean Frailty Index (KFI) and classified into three categories according to the cutpoints. Other physical performances such as BMI, muscle mass index, grip strength, and gait speed measures were performed by experienced researchers specialized in geriatric assessment. comorbidity status using the Charlson comorbidity index, and depressive symptoms using GDS was examined.ResultIn total, 34 subjects (23.6 %) were classified as frail 47 subjects (32.6 %) were classified as prefrail, and 63 subjects (43.8 %) were classified as a non‐frail group. The frail group had higher WMH volume compared to the non‐frail group (p=0.002), and these trends remained significant after linear regression analyses. According to the new subclassification of WMH, using the non‐frail group as a reference, total WMH volume (OR=6.297, p=0.013), JVWMH volume (OR=12.955, p=0.014), and PVWMH (OR=3.382, p=0.025) were associated with frail. Furthermore, according to the path model, only the gait speed mediated the association between WMH and frailty.ConclusionIn our study provides evidence of a cross‐sectional relationship between WMH and frailty, and there is a difference in the association between the subclassification of WMH volume and frailty. Furthermore, we suggest that gait speed could be a useful biomarker for assessment of the frailty.

The Association of White Matter Hyperintensities with Frailty in Patients with Very Mild to Moderate Alzheimer's Disease.

Frailty, one of serious global health problems in the elderly, is a growing concern in patients with Alzheimer's disease (AD) because of its high prevalence in AD and its impact on the prognosis. To investigate the quantitative association between white matter hyperintensities (WMH) and frailty in AD. A total of 144 outpatients were included. All subjects were evaluated by using Korean version of the CERAD assessment battery and diagnosed very mild to moderate AD. WMH volume was calculated using automated segmentation analysis from the 3D MRI image and further partitioned according to the distance from the ventricular surface. Using the Korean Frailty Index, prefrailty was defined by the scores of 3 and 4 and frailty by the score of 5 and higher. In total, 23.6%were frailty, 32.6%were pre-frailty, and 43.8%were classified as a robust group. The frailty group had higher WMH volume compared to the robust group (p = 0.02), and these trends remained significant after linear regression analyses. According to the subclassification of WMH, using the robust group as a reference, total WMH (OR = 6.297, p = 0.013, 95%CI = 1.463-27.114), juxtaventricular WMH (OR = 12.955, p = 0.014, 95%CI = 1.687-99.509), and periventricular WMH (OR = 3.382, p = 0.025, 95%CI = 1.163-9.8531) volumes were associated with frailty, but deep WMH volume was not. A quarter of patients with very mild to moderate AD is suffering from frailty. Our study provides the evidence of a cross-sectional relationship between WMH volume and frailty, and there is a difference in the association between the subclassification of WMH volume and frailty.

Evaluation of the change in retinal thickness after femtosecond laser-assisted laser in situ keratomileusis and photorefractive keratectomy

ABSTRACT Purpose of the study To investigate the change in individual retinal layer thickness by spectral-domain optical coherence tomography (SD-OCT) in eyes underwent femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK) and photorefractive keratectomy (PRK). Methods In patients who underwent PRK and FS-LASIK, changes in the thickness of all retinal layers in the foveal, parafoveal, and perifoveal regions were evaluated by SD-OCT automated segmentation analysis at pre-operatively and different time points post-operatively. Results Seventy-one eyes of 71 patients (38 patients in PRK, 33 patients in LASIK) were included. In the pre-operative period, mean spherical equivalent (SE), mean keratometry, axial length, and segmentation values of the retinal layers were similar (P> .05). In the PRK group, the pre-operative measurements of individual retinal layers did not show a statistically significant difference compared to the post-operative measurements on the 1st day, 1st week, and 1st month. In the FS-LASIK group, the mean inner nuclear layer (INL) thickness one day after the surgery was significantly higher than that before surgery in the foveal (21.22 ± 4.66 µm vs 19.03 ± 4.50 µm, P= .013) and parafoveal regions (41.98 ± 3.70 µm vs 40.56 ± 3.49 µm, P= .044). Conclusions The findings of our study suggest that the increase of INL thickness may be due to temporary structural and circulatory changes of the retina that may occur in the suction phase in the FS-LASIK procedure.

MTT and Blood-Brain Barrier Disruption within Asymptomatic Vascular WM Lesions.

White matter lesions of presumed ischemic origin are associated with progressive cognitive impairment and impaired BBB function. Studying the longitudinal effects of white matter lesion biomarkers that measure changes in perfusion and BBB patency within white matter lesions is required for long-term studies of lesion progression. We studied perfusion and BBB disruption within white matter lesions in asymptomatic subjects. Anatomic imaging was followed by consecutive dynamic contrast-enhanced and DSC imaging. White matter lesions in 21 asymptomatic individuals were determined using a Subject-Specific Sparse Dictionary Learning algorithm with manual correction. Perfusion-related parameters including CBF, MTT, the BBB leakage parameter, and volume transfer constant were determined. MTT was significantly prolonged (7.88 [SD, 1.03] seconds) within white matter lesions compared with normal-appearing white (7.29 [SD, 1.14] seconds) and gray matter (6.67 [SD, 1.35] seconds). The volume transfer constant, measured by dynamic contrast-enhanced imaging, was significantly elevated (0.013 [SD, 0.017] minutes-1) in white matter lesions compared with normal-appearing white matter (0.007 [SD, 0.011] minutes-1). BBB disruption within white matter lesions was detected relative to normal white and gray matter using the DSC-BBB leakage parameter method so that increasing BBB disruption correlated with increasing white matter lesion volume (Spearman correlation coefficient = 0.44; P < .046). A dual-contrast-injection MR imaging protocol combined with a 3D automated segmentation analysis pipeline was used to assess BBB disruption in white matter lesions on the basis of quantitative perfusion measures including the volume transfer constant (dynamic contrast-enhanced imaging), the BBB leakage parameter (DSC), and MTT (DSC). This protocol was able to detect early pathologic changes in otherwise healthy individuals.

Effects of different tamponade materials on macular segmentation after retinal detachment repair.

This study used spectral domain-optical coherence tomography (SD-OCT) to evaluate individual retinal layer thickness in eyes with macula-off rhegmatogenous retinal detachment (RRD) treated with silicone oil (SiO) or gas endotamponades. This was a retrospective, interventional, comparative study. The study included 86 eyes of 43 patients who were divided into 3 groups according to endotamponades: SiO, perfluoropropane (C3F8), and sulfur hexafluoride (SF6). The affected eyes were compared with the fellow eyes of the same patient via SD-OCT automated segmentation analysis. Patients with a follow-up of at least 6months were included in the final analysis. Macular segmentation including the retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), retinal pigment epithelium (RPE), inner retinal layers (IRLs), and outer retinal layers (ORLs) was analyzed. In the SiO group, the mean thickness of each retinal layer including the RNFL, GCL, IPL, ONL, and IRLs within a 1-mm ETDRS subfield of the affected eyes was significantly lower than that of the fellow eyes (P = 0.036, P = 0.028, P = 0.003, P < 0.001, P = 0.013, respectively). There was no significant difference in the C3F8 and SF6 groups (all P > 0.05). The difference between the ONL and IRLs in the SiO-treated eyes differed significantly from that of the gas groups (P = 0.001 and P = 0.045, respectively) The difference in the GCL thickness of the affected eyes and healthy eyes showed a significant correlation with postoperative BCVA changes in the SiO, C3F8, and SF6 groups (P = 0.041, P = 0.048, and P = 0.045, respectively). The findings of our study show that endotamponades used in RRD surgery may have different effects on retinal layers. In addition, SiO may cause undesirable effects on the retinal layers.

Incidental branch retinal artery occlusion on optical coherence tomography angiography presenting as segmental optic atrophy in a child: a case report

BackgroundRetinal artery occlusion is extremely rare in the pediatric population and most patients have risk factors. We report a case of a healthy child with segmental optic atrophy, complicated by incidental branch retinal artery occlusion (BRAO).Case presentationA 10-year-old boy who had a history of his mother’s gestational diabetes presented with an inferonasal visual field defect in the left eye. His best-corrected visual acuities were 20/20 in both eyes (OU). Fundoscopic examination revealed segmental pallor of the left optic disc, thinning of the superotemporal rim, a relative superior entrance of the central retinal artery and superior peripapillary scleral halo. Fluorescein angiography showed patchy filling delays in the corresponding disc area without retinal vascular abnormalities. Spectral domain optical coherence tomography (SD OCT) via automated segmentation analysis demonstrated sectoral absence of the ganglion cell layer and retinal nerve fiber layer with thinning of the inner plexiform layer, inner nuclear layer and outer plexiform layer in the corresponding retina. OCT angiography (OCTA) showed focal attenuation of superficial and intermediate/deep capillary plexuses in the corresponding areas. Systemic evaluation was unremarkable. The patient was diagnosed with segmental optic atrophy caused by incidental BRAO.ConclusionsRetinal vascular occlusions are rare in childhood, and may present as segmental optic atrophy mimicking congenital anomalies. OCTA allows the detection of previous microvascular abnormalities in the chronic phase. To the best of our knowledge, this is the first report of a child with segmental optic atrophy presumably caused by BRAO, which was documented by SD OCT and OCTA in detail.

Improved Cerebrospinal Fluid-Based Discrimination between Alzheimer's Disease Patients and Controls after Correction for Ventricular Volumes.

Cerebrospinal fluid (CSF) biomarkers may support the diagnosis of Alzheimer's disease (AD). We studied if the diagnostic power of AD CSF biomarker concentrations, i.e., Aβ42, total tau (t-tau), and phosphorylated tau (p-tau), is affected by differences in lateral ventricular volume (VV), using CSF biomarker data and magnetic resonance imaging (MRI) scans of 730 subjects, from 13 European Memory Clinics. We developed a Matlab-algorithm for standardized automated segmentation analysis of T1 weighted MRI scans in SPM8 for determining VV, and computed its ratio with total intracranial volume (TIV) as proxy for total CSF volume. The diagnostic power of CSF biomarkers (and their combination), either corrected for VV/TIV ratio or not, was determined by ROC analysis. CSF Aβ42 levels inversely correlated to VV/TIV in the whole study population (Aβ42: r = -0.28; p < 0.0001). For CSF t-tau and p-tau, this association only reached statistical significance in the combined MCI and AD group (t-tau: r = -0.15; p-tau: r = -0.13; both p < 0.01). Correction for differences in VV/TIV improved the differentiation of AD versus controls based on CSF Aβ42 alone (AUC: 0.75 versus 0.81) or in combination with t-tau (AUC: 0.81 versus 0.91). In conclusion, differences in VV may be an important confounder in interpreting CSF Aβ42 levels.

Automatic versus Manual Segmentation of Choroidal Neovascularization Lesions Using Optical Coherence Tomography

1.1.Purpose: To measure and quantify choroidal neovascularization (CNV) lesion size in classic lesions visualized on Spectral Domain-Optical Coherence Tomography (SD-OCT) using automated segmentation analysis and confirm whether further refinement improves the accuracy of disease regression after loading dose Anti-VEGF injections. 1.2.Methodology: A retrospective study of 10 macular degeneration patients diagnosed with CNV. Blinded observers, trained to detect changes on OCT, delineated boundaries of CNV lesions using SD-OCT (Topcon 2000) with automated software and then modified segmentation manually before and after loading dose Ranbizumab injections. Automated measurements were then compared to manual segmentation values. Statistical analysis was performed, taking into account inter-observer variability. 1.3.Results: Automatic and manual segmentation measurements are similar in 1) retinal area and fovea center values both pre-and post-injection; and 2) retinal volume post-injection. Retinal volume pre-injection is 1) similar between the two blinded observers; 2) varies between automatic measurements and observers in some patients; and 3) underestimated for all patients in the automatic measurements. Overall, automatic segmentation detects a general reduction in CNV lesion size following loading dose injections. 1.4.Conclusion: SD-OCT automated segmentation software detects CNV lesions and reports size reduction after the third anti-VEGF injection. SD-OCT automatic segmentation using Topcon segmentation analysis in this small cohort is an accurate diagnostic tool to measure CNV surface area and volume as a biomarker of CNV regression.

In vivo imaging of neurodegeneration in dementia with Lewy bodies (DLB).

For almost two decades, O'Brien and colleagues have investigated virtually every facet of dementia with Lewy bodies (DLB), phenomenology, treatment, and neurobiology, ranging from genetics to post-mortem and in vivo imaging studies. The latest study from this group, reported here, describes differences in regional grey matter volumes using magnetic resonance (MR) imaging and an automated segmentation analysis method in a well-characterized sample of patients with Alzheimer disease (AD), DLB, and a healthy control group (Watson et al., 2015). The study incorporated detailed psychometric assessments of cognitive and motor functions for correlation with the grey matter volumes, and age, gender and dementia severity were included as covariates in the statistical analysis. The key observations are relatively greater hippocampal volumes and lower subcortical volumes in DLB compared to AD, but it is to be noted that most of these differences in subcortical volume were demonstrated indirectly through comparisons of the disease groups with age-matched healthy control subjects. Thus, replication in studies that make direct comparisons between DLB and AD subjects, perhaps in a larger sample size, is necessary. Still, these results highlight the potential for MR imaging to provide indicators of the extent of the neurodegenerative process in DLB. Furthermore, the results underscore the importance of correcting molecular imaging data for the effects of cerebral atrophy (partial volume correction) that may further enhance the ability of these methods to reveal pathophysiological processes.

Evaluating Efficacy of Aflibercept in Refractory Exudative Age-Related Macular Degeneration With OCT Segmentation Volumetric Analysis.

To use automated segmentation software to analyze spectral-domain optical coherence tomography (SD-OCT) scans and evaluate the effectiveness of aflibercept (Eylea; Regeneron, Tarrytown, NY) in the treatment of patients with exudative age-related macular degeneration (AMD) refractory to other treatments. Retrospective chart review of 16 patients refractory to bevacizumab (Avastin; Genentech, South San Francisco, CA)/ranibizumab (Lucentis; Genentech, San Francisco, CA) treatment was conducted. Visual acuity, central foveal thickness (CFT), maximum fluid height, pigment epithelial detachment (PED) volume, sub-retinal fluid (SRF) volume, fluid-free time interval, and adverse effects were evaluated. Automated segmentation analysis was used to quantify improvement. With aflibercept treatment, there was a statistically significant improvement in visual acuity by 1 line (P = .020), in CFT by 74.02 µm (P = .001), and in maximum fluid height by 31.9 µm (P= .011). Total PED and SRF volume also decreased significantly by 1.50 µm(3) × 10(8) µm(3) (P = .013). Anatomic improvement was confirmed by automated segmentation analysis. This study demonstrates utility of automated segmentation software in quantifying anatomic improvement with aflibercept treatment in exudative AMD refractory to other anti-vascular endothelial growth factor treatments.

Differential Vulnerability of Retinal Layers to Early Age-Related Macular Degeneration: Evidence by SD-OCT Segmentation Analysis

We evaluated layer-by-layer retinal thickness in spectral-domain optical coherence tomography (SD-OCT), determined by automated segmentation analysis (ASA) software in healthy and early age-related maculopathy (ARM) eyes. There were 57 eyes (specifically, 19 healthy eyes under 60 years old, 19 healthy eyes over 60, and 19 ARM eyes) recruited into this cross-sectional study. The mean ages were 36.78 (SD, ±13.82), 69.89 (SD, ±6.14), and 66.10 (SD, ±8.67) years, respectively, in the three study groups. The SD-OCT scans were transferred into a dedicated software program that performed automated segmentation of different retinal layers. Automated layer segmentation showed clear boundaries between the following layers: retinal nerve fiber layer (RNFL), ganglion cell layer plus inner plexiform layer (GCL+IPL), inner nuclear layer plus outer plexiform layer (INL+OPL), outer nuclear layer (ONL), and RPE complex. The thickness of the RNFL, ONL, and RPE layers did not show a statistically significant change across the three groups by ANOVA (P = 0.10, P = 0.09, P = 0.15, respectively). The thickness of GCL+IPL and INL+OPL was significantly different across the groups (P < 0.01), being reduced in the ARM eyes compared to healthy eyes, under and over 60 years old. The early morphologic involvement of the GCL+IPL and INL+OPL layers in ARM eyes, as revealed by the ASA, could be related to early anatomic changes described in the inner retina of ARM eyes. This finding may represent a morphologic correlation to the deficits in postreceptoral retinal function in ARM eyes.

Tissue segmentation-assisted analysis of fMRI for human motor response: an approach combining artificial neural network and fuzzy C means.

The authors have developed an automated algorithm for segmentation of magnetic resonance images (MRI) of the human brain. They investigated the quantitative analysis of tissue-specific human motor response through an approach combining gradient echo functional MRI and automated segmentation analysis. Fifteen healthy volunteers, placed in a 1.5 T clinical MR imager, performed a self-paced finger opposition throughout the activation periods. T1-weighted images (WI), T2WI, and proton density WI were acquired for segmentation analysis. Single-slice axial T2* fast low-angle shot (FLASH) images were obtained during the functional study. Pixelwise cross-correlation analysis was performed to obtain an activation map. A cascaded algorithm, combining Kohonen feature maps and fuzzy C means, was applied for segmentation. After processing, masks for gray matter, white matter, small vessels, and large vessels were generated. Tissue-specific analysis showed a signal change rate of 4.53% in gray matter, 2.98% in white matter, 5.79% in small vessels, and 7.24% in large vessels. Different temporal patterns as well as different levels of activation were identified in the functional response from various types of tissue. High correlation exists between cortical gray matter and subcortical white matter (r = 0.957), while the vessel behaves somewhat different temporally. The cortical gray matter fits best to the assumed input function (r = 0.957) followed by subcortical white matter (r = 0.829) and vessels (r = 0.726). The automated algorithm of tissue-specific analysis thus can assist functional MRI studies with different modalities of response in different brain regions.