Measurement Of Lumen Diameter Research Articles

Deep learning fully convolution network for lumen characterization in diabetic patients using carotid ultrasound: a tool for stroke risk.

Manual ultrasound (US)-based methods are adapted for lumen diameter (LD) measurement to estimate the risk of stroke but they are tedious, error prone, and subjective causing variability. We propose an automated deep learning (DL)-based system for lumen detection. The system consists of a combination of two DL systems: encoder and decoder for lumen segmentation. The encoder employs a 13-layer convolution neural network model (CNN) for rich feature extraction. The decoder employs three up-sample layers of fully convolution network (FCN) for lumen segmentation. Three sets of manual tracings were used during the training paradigm leading to the design of three DL systems. Cross-validation protocol was implemented for all three DL systems. Using the polyline distance metric, the precision of merit for three DL systems over 407 US scans was 99.61%, 97.75%, and 99.89%, respectively. The Jaccard index and Dice similarity of DL lumen segmented region against three ground truth (GT) regions were 0.94, 0.94, and 0.93 and 0.97, 0.97, and 0.97, respectively. The corresponding AUC for three DL systems was 0.95, 0.91, and 0.93. The experimental results demonstrated superior performance of proposed deep learning system over conventional methods in literature. Graphical abstract ᅟ.

Comparison of hemodialysis arteriovenous fistula blood flow rates measured by Doppler ultrasound and phase-contrast magnetic resonance imaging

ObjectiveThe objective of this study was to compare blood flow rates measured by Doppler ultrasound (DUS) and phase-contrast magnetic resonance imaging (MRI) in patients having a hemodialysis arteriovenous fistula (AVF) and to identify scenarios in which there was significant discordance between these two approaches. MethodsBlood flow rates in the proximal artery (PA) and draining vein (DV) of newly created upper extremity AVFs were measured and compared using DUS and phase-contrast MRI at 1 day, 6 weeks, and 6 months postoperatively. ResultsBlood flow rates in the PA measured by DUS (1155 ± 907 mL/min, mean ± standard deviation) and by MRI (1170 ± 657 mL/min) were not statistically different (P = .812) based on 78 data pairs from 49 patients. DV DUS flow (1277 ± 995 mL/min) and MRI flow (1130 ± 655 mL/min) were also not statistically different (P = .071) based on 64 data pairs. In both PA and DV, the two methods substantially agreed with each other (Cohen κ: PA, 0.66; DV, 0.67) when flow rates were put into four clinically relevant categories (<300, 300-599, 600-1499, and ≥1500 mL/min). The Bland-Altman analyses of DUS and MRI flow identified six and four outliers for PA and DV, respectively. Seven outliers had higher DUS than MRI flow, with all DUS scan sites having a large lumen or significant local curvature; the other three had lower DUS flow, partly due to an underestimation of lumen diameter by DUS. ConclusionsDUS and MRI flow rates are generally comparable in both PA and DV. When DUS is used for flow measurements, careful attention to accurate lumen diameter measurements is needed and scan sites with marked curvature should be avoided. Our result may improve the accuracy of DUS-measured AVF blood flow rate.

Intra- and inter-operator reproducibility of automated cloud-based carotid lumen diameter ultrasound measurement

BackgroundCommon carotid artery lumen diameter (LD) ultrasound measurement systems are either manual or semi-automated and lack reproducibility and variability studies. This pilot study presents an automated and cloud-based LD measurements software system (AtheroCloud) and evaluates its: (i) intra/inter-operator reproducibility and (ii) intra/inter-observer variability. Methods100 patients (83M, mean age: 68±11years), IRB approved, consisted of L/R CCA artery (200 ultrasound images), acquired using a 7.5-MHz linear transducer. The intra/inter-operator reproducibility was verified using three operator’s readings. Near-wall and far carotid wall borders were manually traced by two observers for intra/inter-observer variability analysis. ResultsThe mean coefficient of correlation (CC) for intra- and inter-operator reproducibility between all the three automated reading pairs were: 0.99 (P<0.0001) and 0.97 (P<0.0001), respectively. The mean CC for intra- and inter-observer variability between both the manual reading pairs were 0.98 (P<0.0001) and 0.98 (P<0.0001), respectively. The Figure-of-Merit between the mean of the three automated readings against the four manuals were 98.32%, 99.50%, 98.94% and 98.49%, respectively. ConclusionsThe AtheroCloud LD measurement system showed high intra/inter-operator reproducibility hence can be adapted for vascular screening mode or pharmaceutical clinical trial mode.

Web-based accurate measurements of carotid lumen diameter and stenosis severity: An ultrasound-based clinical tool for stroke risk assessment during multicenter clinical trials

BackgroundThis pilot study presents a completely automated, novel, smart, cloud-based, point-of-care system for (a) carotid lumen diameter (LD); (b) stenosis severity index (SSI) and (c) total lumen area (TLA) measurement using B-mode ultrasound. The proposed system was (i) validated against manual reading taken by the Neurologist and (ii) benchmarked against the commercially available system. MethodOne hundred patients (73 M/27 F, mean age: 68 ± 11 years), institutional review board approved, written informed consent, consisted of left/right common carotid artery (200 ultrasound scans) were acquired using a 7.5-MHz linear transducer. ResultsThe measured mean LD for left and right carotids were (in mm): (i) for proposed system (6.49 ± 1.77, 6.66 ± 1.70); and (ii) for manual (6.29 ± 1.79, 6.45 ± 1.63), respectively and coefficient of correlation between cloud-based automated against manual were 0.98 (P < 0.0001) and 0.99 (P < 0.0001), respectively. The corresponding TLA error, Precision-of-Merit, and Figure-of-Merit when measured against the manual were: 4.56 ± 3.54%, 96.18 ± 3.21%, and 96.85%, respectively.The AUC for the receiving operating characteristics for the cloud-based system was: 1.0. Four statistical tests such as: Two-tailed z-test, Mann-Whitney test, Kolmogorov-Smirnov (KS) and one-way ANOVA were performed to demonstrate consistency and reliability. ConclusionsThe proposed system is reliable, accurate, fast, completely automated, anytime-anywhere solution for multi-center clinical trials and routine vascular screening.

PULMONARY ARTERY WALL THICKNESS IN CHILDREN WITH FONTAN PHYSIOLOGY – AN OPTICAL COHERENCE TOMOGRAPHY CASE CONTROL STUDY

Fontan failure in patients with preserved ventricular function is not well understood. Loss of pulsatile flow in the pulmonary arteries leads to lack of shear stress, which is believed to result in endothelial dysfunction. This endothelial dysfunction may further promote vascular remodelling. Subsequent increased pulmonary vascular resistance is considered to be a potential contributing mechanism for Fontan failure. We sought to perform an in vivo case control study to evaluate structural changes in the pulmonary arteries of children with a Fontan circulation compared to those with a normal pulmonary circulation. Since May 2016, we have recruited patients undergoing cardiac catheterization at BC Children’s Hospital. The control group comprised of children with normal pulmonary circulation undergoing cardiac catheterization or invasive electrophysiology evaluation. We performed intravascular imaging of the pulmonary arteries using Optical Coherence Tomography (OCT, Abbott). For quantitative OCT image analyses, we identified a series of 10 cross-sectional frames that were each ≥0.5 mm apart along the vessel. Using digital planimetry, we measured lumen diameter (mm), lumen cross-sectional area (CSA, mm2), wall CSA (mm2), vessel CSA (lumen+wall CSA, mm2) and mean wall thickness (mm) for each frame. To standardize wall thickness by vessel size, we calculated wall CSA to vessel CSA ratios. We calculated median values across frames for each case. Between-group differences were assessed by Mann-Whitney U tests; associations by Spearman Rank correlation (Stata v. 14.0; p < 0.05). We quantitatively analysed OCT images of the pulmonary arteries in 10 children with a Fontan circulation (10.8±3.9yrs at OCT, 40% female) and 8 control children (10.5±4.2yrs at OCT, 75% female). Overall, there were no significant differences between groups in terms of wall thickness (overall median 0.11mm, interquartile range 0.10-0.15) or wall/vessel ratio (0.13, IQR 0.11-0.15). There was no association between wall thickness or wall/vessel ratio with age at OCT, age at Fontan completion, or time since Fontan completion. Median pulmonary artery pressure at time of OCT was 11.8mmHg (10.5-14.0), which was not associated with normalized wall thickness. OCT findings suggest that during childhood, pulmonary artery wall dimensions are normal in children with Fontan physiology and reassuring hemodynamic status. Further evaluation of vascular function and correlating structure with function in this population would be worthwhile. Serial evaluation of pulmonary artery structure and correlation with clinical course into adulthood is needed.

Preoperative thoracic false lumen branches are predictors of aortic enlargement after stent grafting for DeBakey IIIb aortic dissection

ObjectiveThe study objective was to assess the effect of preoperative thoracic false lumen branches on thoracic aortic enlargement along the stent graft after thoracic endovascular aortic repair for DeBakey IIIb aortic dissection. MethodsFrom January 2011 to December 2013, 67 patients who underwent thoracic endovascular aortic repair for DeBakey IIIb aortic dissection were retrospectively investigated. We assessed preoperative thoracic false lumen branches and diameter measurements at the level of the tracheal carina. Patients with a median follow-up of 12.2 months (interquartile range, 4.3-26.6 months) were categorized into 2 groups based on a receiver operating characteristic curve analysis: group A (preoperative thoracic false lumen branches ≥8, n = 28) and group B (preoperative thoracic false lumen branches <8, n = 39). Diameter changes over time were evaluated using a mixed model approach. A multivariate Cox regression analysis was used to study the influence of the preoperative thoracic false lumen branches on thoracic aortic enlargement along the stent graft. ResultsSix patients experienced thoracic aortic enlargement along the stent graft during follow-up (6 in group A, 0 in group B). The cumulative thoracic aortic enlargement along the stent-graft rate was higher in group A than in group B (log-rank P < .01). Diameter data showed significantly more reduction of the thoracic false lumen from preprocedure to 12 months in group B than in group A (change difference, 2.51; standard error, 0.99; P = .01). Complete false lumen thrombosis was more prominent in group B than in group A at each follow-up time point. After multivariate adjustment, preoperative thoracic false lumen branches were associated with thoracic aortic enlargement along the stent graft (hazard ratio, 2.92; 95% confidence interval, 1.06-8.01). ConclusionsPreoperative thoracic false lumen branches are a morphologic predictor of thoracic aortic enlargement along the stent graft in DeBakey IIIb aortic dissection after thoracic endovascular aortic repair.

Impact of advanced modeled iterative reconstruction on interreader agreement in coronary artery measurements

ObjectivesTo evaluate the influence of advanced modeled iterative reconstruction (ADMIRE) on coronary artery computed tomography angiography (cCTA) measurements in comparison to filtered back projection (FBP). Material and methodsPhantom scans and coronary CTA studies of 27 patients were acquired with a third generation dual-source CT scanner. Images were reconstructed using FBP and ADMIRE. Phantom measurements were used as reference standard. In patient studies, representative axial slices of each coronary artery segment without (n=308) and with coronary plaques (n=40) were assessed in identical positions for comparison of FBP and ADMIRE reconstructions. Image analyses included quality assessment, phantom and coronary artery measurements, plaque analysis, and interreader agreement of two independent and blinded readers. ResultsMean image noise was lower on ADMIRE reconstructions with 31.3±9.9 HU compared to 55.9±15.7 HU on FBP reconstructions (p<0.001). Measurement precision and interreader agreement of both observers were assessed satisfactorily on phantom images in comparison to the full width half maximum method. In patients, correlation of lumen diameters of both observers improved using ADMIRE with a Pearson’s r=0.987 (95% confidence interval [CI], 0.983–0.989; p<0.001) compared to FBP images with r=0.939 (95% CI, 0.924–0.951; p<0.001). Applying ADMIRE, agreement of both observers for lumen diameter measurements significantly increased (p<0.001). This was also observed for the degree of stenosis (p<0.001) with r=0.560 using FBP (95% CI, 0.301–0.742) and with r=0.818 using ADMIRE (95% CI, 0.680–0.900). Plaque density measurements correlated closely with a Pearson’s r of 0.951 in FBP (95% CI, 0.909–0.974) and 0.967 in ADMIRE (95% CI, 0.939–0.983). ConclusionsAdvanced modeled iterative reconstruction significantly improves coronary artery assessment in coronary CTA in comparison to FBP by improved image quality due to image noise removal. This renders improved interobserver agreement for coronary lumen diameter and degree of stenosis measurements without influencing mean plaque attenuation.

Post-processing reproducibility of the structural characteristics of the common carotid artery in a Flemish population

IntroductionCommon carotid artery (CCA) intima-media thickness (IMT), lumen diameter, and maximum plaque thickness were assessed on ultrasound images. The objective of the study was to evaluate the intra- and inter-reader reproducibility of the measurements following a standardised protocol. MethodsTwo readers performed the off-line measurements on B-mode ultrasound images of the distal CCA, in a randomly selected subset (n = 60) from a Flemish population cohort (FLEMENGHO). We calculated the coefficient of variation, the interclass correlation coefficient (ICC) and reproducibility according to the Bland–Altman method. ResultsThe intra-reader bias for the measurements of left and right side CCA IMT were −0.003 ± 0.04 mm (p = 0.55) and 0.01 ± 0.04 mm (p = 0.03), respectively. The intra-reader bias of the lumen diameter was −0.04 ± 0.25 mm (p = 0.27) for the left and 0.02 ± 0.22 mm (p = 0.45) for the right side. The measurements for the maximum plaque thickness showed no intra-reader differences with bias 0.07 ± 0.2 mm (p = 0.26) for the left and −0.03 ± 0.2 mm (p = 0.55) for the right side. The inter-reader analysis showed good reproducibility for the left and right side CCA IMT with bias 0.004 ± 0.06 mm (p = 0.57) and −0.008 ± 0.05 mm (p = 0.19), respectively, but the lumen diameter measurements showed inter-reader differences, with bias 0.17 ± 0.27 mm (p < 0.0001) for the left and 0.10 ± 0.21 mm (p = 0.0006) for the right side. The inter-reader bias for the maximum plaque thickness were 0.07 ± 0.2 mm (p = 0.21) and −0.1 ± 0.4 mm (p = 0.26) for the left and right side, respectively. ConclusionThe results demonstrated a reliable reproducibility of carotid wall structural measurements, allowing for an adequate further analysis of the entire population cohort.

Ultrasound detection of altered placental vascular morphology based on hemodynamic pulse wave reflection.

Abnormally pulsatile umbilical artery (UA) Doppler ultrasound velocity waveforms are a hallmark of severe or early onset placental-mediated intrauterine growth restriction (IUGR), whereas milder late onset IUGR pregnancies typically have normal UA pulsatility. The diagnostic utility of these waveforms to detect placental pathology is thus limited and hampered by factors outside of the placental circulation, including fetal cardiac output. In view of these limitations, we hypothesized that these Doppler waveforms could be more clearly understood as a reflection phenomenon and that a reflected pulse pressure wave is present in the UA that originates from the placenta and propagates backward along the UA. To investigate this, we developed a new ultrasound approach to isolate that portion of the UA Doppler waveform that arises from a pulse pressure wave propagating backward along the UA. Ultrasound measurements of UA lumen diameter and flow waveforms were used to decompose the observed flow waveform into its forward and reflected components. Evaluation of CD1 and C57BL/6 mice at embryonic day (E)15.5 and E17.5 demonstrated that the reflected waveforms diverged between the strains at E17.5, mirroring known changes in the fractal geometry of fetoplacental arteries at these ages. These experiments demonstrate the feasibility of noninvasively measuring wave reflections that originate from the fetoplacental circulation. The observed reflections were consistent with theoretical predictions based on the area ratio of parent to daughters at bifurcations in fetoplacental arteries suggesting that this approach could be used in the diagnosis of fetoplacental vascular pathology that is prevalent in human IUGR. Given that the proposed measurements represent a subset of those currently used in human fetal surveillance, the adaptation of this technology could extend the diagnostic utility of Doppler ultrasound in the detection of placental vascular pathologies that cause IUGR.NEW & NOTEWORTHY Here, we describe a novel approach to noninvasively detect microvascular changes in the fetoplacental circulation using ultrasound. The technique is based on detecting reflection pulse pressure waves that travel along the umbilical artery. Using a proof-of-principle study, we demonstrate the feasibility of the technique in two strains of experimental mice.

The Comparison between Digital Subtraction Angiography, CT Angiography, and Doppler Ultrasonography in Evaluation and Assessment of Carotid Artery Stenosis

Background: Common angiography or digital subtraction angiography (DSA) is the gold standard protocol for diagnosis of carotid artery stenosis. However, this method has very high delivered X-ray doses to patient and personnel as an invasive diagnostic protocol. The progress of noninvasive or minimally invasive diagnostic techniques like Doppler ultrasonography (DUS), CT angiography (CTA), and MR angiography (MRA) has improved the detection and evaluation of stenosis lesions. The aim of this study was to evaluate the usefulness and accuracy of non-invasive DUS and CTA, attempting in this way to restrict DSA only for final proof of high-grade stenosis. Methods: 25 male patients with carotid artery stenosis were examined with CTA, DUS, and DSA. The lumen diameter of carotid artery was measured and compared with CTA and DUS. The results of CTA and DUS were compared and correlated with DSA results as a reference. Results: Data of lumen diameter measurements in ultrasonography and CTA (for internal and common carotid artery) showed no significant differences between the two methods. Mean internal/common lumen artery in stenosis region was 3.745/5.114 and 3.643/5.000 millimeters for CTA and DUS, respectively. The results (mean ± standard deviation) of moderate to severe carotid stenosis obtained from CTA, DUS, and DSA in stenoses ≥ 50% were 67.8 ± 10.82, 65.6 ± 13.25, and 71.2 ± 11.2 (in percentage), respectively. The Spearman correlations of CTA and DUS results with DSA results were 0.865 and 0.812, respectively. Conclusions: Significant correlations were found in our study between CTA/DSA and DUS/DSA. We showed that the accuracy of CTA and Doppler ultrasonography was appropriate in comparison with DSA results for male patients with carotid stenosis ≥ 50%. We also showed that measurement of PSV could be a good parameter for evaluating carotid stenosis like PSVr in Doppler ultrasonography.

Quantifying Intracranial Internal Carotid Artery Stenosis on MR Angiography.

Intracranial atherosclerosis is a common cause of ischemic stroke. Intracranial stenosis is most commonly quantified by the Warfarin-Aspirin Symptomatic Intracranial Disease method, which involves calculating a ratio of luminal diameter measurements on conventional angiography. Our purpose was to determine whether a single linear measurement of the narrowest caliber of the intracranial ICA on MRA can accurately predict Warfarin-Aspirin Symptomatic Intracranial Disease stenosis measurements. We identified patients from a prospective stroke registry who had undergone head MRAs to quantitatively evaluate the degree of Warfarin-Aspirin Symptomatic Intracranial Disease-derived stenosis in each intracranial ICA. We also made a single linear millimeter measurement at the site of maximal narrowing of the ICA. We calculated a correlation coefficient between the lumen diameter in millimeters and percentage Warfarin-Aspirin Symptomatic Intracranial Disease stenosis. We performed receiver operating characteristic analysis to determine optimal luminal diameter cutoff values. In 386 unique intracranial ICAs, we found a strong linear relationship between single lumen measurements and Warfarin-Aspirin Symptomatic Intracranial Disease-style stenosis measurements (R = -0.84, P < .0001). We found that ICA lumen diameters of ≤2.1 and ≤1.3 mm were optimal cutoffs for identifying patients with ≥50% stenosis and ≥70% stenosis, respectively (area under the curve = 0.96 and 0.99, respectively). There is a strong linear relationship between the narrowest lumen diameter of the intracranial ICA and percentage stenosis. Our results suggest that a single lumen diameter measurement on MRA allows accurate estimation of Warfarin-Aspirin Symptomatic Intracranial Disease stenosis, which may affect risk stratification and treatment decisions.

Integrating trans-abdominal ultrasonography with fecal steroid metabolite monitoring to accurately diagnose pregnancy and predict the timing of parturition in the red panda (Ailurus fulgens styani).

Red pandas (Ailurus fulgens styani) exhibit a variable gestation length and may experience a pseudopregnancy indistinguishable from true pregnancy; therefore, it is not possible to deduce an individual's true pregnancy status and parturition date based on breeding dates or fecal progesterone excretion patterns alone. The goal of this study was to evaluate the use of transabdominal ultrasonography for pregnancy diagnosis in red pandas. Two to three females were monitored over 4 consecutive years, generating a total of seven profiles (four pregnancies, two pseudopregnancies, and one lost pregnancy). Fecal samples were collected and assayed for progesterone (P4) and estrogen conjugate (EC) to characterize patterns associated with breeding activity and parturition events. Animals were trained for voluntary transabdominal ultrasound and examinations were performed weekly. Breeding behaviors and fecal EC data suggest that the estrus cycle of this species is 11-12 days in length. Fecal steroid metabolite analyses also revealed that neither P4 nor EC concentrations were suitable indicators of pregnancy in this species; however, a secondary increase in P4 occurred 69-71 days prior to parturition in all pregnant females, presumably coinciding with embryo implantation. Using ultrasonography, embryos were detected as early as 62 days post-breeding/50 days pre-partum and serial measurements of uterine lumen diameter were documented throughout four pregnancies. Advances in reproductive diagnostics, such as the implementation of ultrasonography, may facilitate improved husbandry of pregnant females and allow for the accurate prediction of parturition.

Accurate lumen diameter measurement in curved vessels in carotid ultrasound: an iterative scale-space and spatial transformation approach.

Monitoring of cerebrovascular diseases via carotid ultrasound has started to become a routine. The measurement of image-based lumen diameter (LD) or inter-adventitial diameter (IAD) is a promising approach for quantification of the degree of stenosis. The manual measurements of LD/IAD are not reliable, subjective and slow. The curvature associated with the vessels along with non-uniformity in the plaque growth poses further challenges. This study uses a novel and generalized approach for automated LD and IAD measurement based on a combination of spatial transformation and scale-space. In this iterative procedure, the scale-space is first used to get the lumen axis which is then used with spatial image transformation paradigm to get a transformed image. The scale-space is then reapplied to retrieve the lumen region and boundary in the transformed framework. Then, inverse transformation is applied to display the results in original image framework. Two hundred and two patients' left and right common carotid artery (404 carotid images) B-mode ultrasound images were retrospectively analyzed. The validation of our algorithm has done against the two manual expert tracings. The coefficient of correlation between the two manual tracings for LD was 0.98 (p<0.0001) and 0.99 (p<0.0001), respectively. The precision of merit between the manual expert tracings and the automated system was 97.7 and 98.7%, respectively. The experimental analysis demonstrated superior performance of the proposed method over conventional approaches. Several statistical tests demonstrated the stability and reliability of the automated system.

A Review on Atherosclerotic Biology, Wall Stiffness, Physics of Elasticity, and Its Ultrasound-Based Measurement.

Functional and structural changes in the common carotid artery are biomarkers for cardiovascular risk. Current methods for measuring functional changes include pulse wave velocity, compliance, distensibility, strain, stress, stiffness, and elasticity derived from arterial waveforms. The review is focused on the ultrasound-based carotid artery elasticity and stiffness measurements covering the physics of elasticity and linking it to biological evolution of arterial stiffness. The paper also presents evolution of plaque with a focus on the pathophysiologic cascade leading to arterial hardening. Using the concept of strain, and image-based elasticity, the paper then reviews the lumen diameter and carotid intima-media thickness measurements in combined temporal and spatial domains. Finally, the review presents the factors which influence the understanding of atherosclerotic disease formation and cardiovascular risk including arterial stiffness, tissue morphological characteristics, and image-based elasticity measurement.

Intra-arterial injection of iloprost reduces the risk of early recoil after balloon angioplasty of below-the-knee vessels in patients with critical limb ischemia.

Previous studies demonstrated that early recoil is frequently observed in patients undergoing balloon angioplasty. The aim of this study was to evaluate the impact of intra-arterial administration of iloprost (Endoprost®, Italfarmaco S.p.A., Milan, Italy) on early elastic recoil after balloon angioplasty of below-the-knee (BTK) vessels in patients with critical limb ischemia (CLI). Between January 2015 and December 2015 32 patients with CLI underwent balloon angioplasty of at least one BTK vessel followed by intra-arterial administration of iloprost. Early elastic recoil was defined as residual lumen compromise >10%. Early elastic recoil was determined on the basis of minimal lumen diameter (MLD) measurements at baseline (MLDbaseline), immediately after BTK balloon angioplasty (MLDpostdilation), and 15 minutes thereafter (MLD15min). Patients were predominantly female (18/32, 56.2%) with a mean age of 79.6 years (range 68-87). Most of the patients were diabetics (25/32, 78.1%). An occlusion was present in 24 cases (75%). Mean BTK lesion length was 144.1 mm (range 22-320). Mean MLD measurements were 0.1 mm (range 0-0.5; MLDbaseline), 2.5 mm (range 1.9-3; MLDpostdilation), and 1.9 mm (range 0.7-3; MLD15min). Early elastic recoil was recorded in 14 patients (43.8%). The mean percentage of elastic recoil after 15 minutes was 21.4%. In our experience intra-arterial administration of iloprost reduces the risk of early elastic recoil after balloon angioplasty of BTK vessels in patients with CLI. Further analyses with larger population studies and randomized trials are needed to validate this therapeutic option.

Ultrasound-Based Automated Carotid Lumen Diameter/Stenosis Measurement and its Validation System

Objective Degree of carotid stenosis is an important predictor to assess risk of stroke. Systolic velocity-based methods for lumen diameter and stenosis measurement are subjective. Image-based methods face a challenge because of low gradients in media and intima walls. Methods This article presents AtheroEdge™ 2.0, a two-stage process for automated carotid lumen diameter measurement that combats the above challenges. Stage one uses spectral analysis based on the hypothesis that far-wall adventitia is brightest. Stage two uses lumen pixel region identification based on the assumption that blood flow has constant density. Using global and local processing, lumen boundaries are detected. This clinical system outputs lumen diameter along with stenosis severity index (SSI). Results Our database consists of institutional review board–approved 202 patients (males/females: 155/47) left and right common carotid artery images (404 images, Toshiba scanner). Two trained neuro radiologists performed manual lumen border tracings using ImgTracer™ software. The coefficient of correlation between automated and two manual readings was 0.91 and 0.92. Dice similarity and Jaccard index were 95.82%, 95.72% and 92.10%, 91.92%, respectively. The mean diameter error between automated and two manual readings was 0.27 ± 0.26 and 0.26 ± 0.28 mm, respectively. Precision of merit was 98.05% and 99.03% with respect to two readings. SSI showed 97% accuracy. Conclusions The image-based automated carotid lumen diameter and stenosis measurement system is fast, accurate, and reliable.

Binding of EBP50 to Nox organizing subunit p47phox is pivotal to cellular reactive species generation and altered vascular phenotype

Despite numerous reports implicating NADPH oxidases (Nox) in the pathogenesis of many diseases, precise regulation of this family of professional reactive oxygen species (ROS) producers remains unclear. A unique member of this family, Nox1 oxidase, functions as either a canonical or hybrid system using Nox organizing subunit 1 (NoxO1) or p47(phox), respectively, the latter of which is functional in vascular smooth muscle cells (VSMC). In this manuscript, we identify critical requirement of ezrin-radixin-moesin-binding phosphoprotein 50 (EBP50; aka NHERF1) for Nox1 activation and downstream responses. Superoxide (O2 (•-)) production induced by angiotensin II (AngII) was absent in mouse EBP50 KO VSMC vs. WT. Moreover, ex vivo incubation of aortas with AngII showed a significant increase in O2 (•-) in WT but not EBP50 or Nox1 nulls. Similarly, lipopolysaccharide (LPS)-induced oxidative stress was attenuated in femoral arteries from EBP50 KO vs. WT. In silico analyses confirmed by confocal microscopy, immunoprecipitation, proximity ligation assay, FRET, and gain-/loss-of-function mutagenesis revealed binding of EBP50, via its PDZ domains, to a specific motif in p47(phox) Functional studies revealed AngII-induced hypertrophy was absent in EBP50 KOs, and in VSMC overexpressing EBP50, Nox1 gene silencing abolished VSMC hypertrophy. Finally, ex vivo measurement of lumen diameter in mouse resistance arteries exhibited attenuated AngII-induced vasoconstriction in EBP50 KO vs. WT. Taken together, our data identify EBP50 as a previously unidentified regulator of Nox1 and support that it promotes Nox1 activity by binding p47(phox) This interaction is pivotal for agonist-induced smooth muscle ROS, hypertrophy, and vasoconstriction and has implications for ROS-mediated physiological and pathophysiological processes.

34 Decreased dilation of hippocampal arterioles in a rat model of preeclampsia

Introduction Women with preeclampsia (PE) and eclampsia have increased incidence of white matter lesions in the brain and self-report cognitive impairment later in life, suggesting seizures during PE may lead to long-lasting brain injury. The hippocampus, a brain region central to cognition, is more susceptible to seizure-induced injury due to less effective functional hyperemia. How PE affects the function and structure of the hippocampal vasculature remains unknown, but could further limit functional hyperemia and potentiate seizure-induced injury. Objective We tested the hypothesis that hippocampal arterioles (HpAs) in PE have impaired responses to mediators of dilation generated during seizure including extracellular potassium (K+) and nitric oxide (NO) and undergo inward remodeling that limits blood flow to the hippocampus during seizure. Methods Sprague Dawley rats were nonpregnant (NP; n = 6), pregnant (P; d20; n = 6) or with PE (induced by a high cholesterol diet gestational days 7–20; n = 6). HpAs were isolated and pressurized to 60 mmHg in an arteriograph chamber. The function of HpAs was investigated by measuring changes in lumen diameter in response to the small- and intermediate-conductance calcium-activated potassium (SK/IK) channel agonist NS309, and in response to increasing K+ concentration from 3–15 mM to activate inward rectifier potassium (KIR) channels. Basal production of NO and the sensitivity of vascular smooth muscle to NO were investigated using the NO synthase (NOS) inhibitor NG-nitro-L-arginine methyl ester (L-NAME, 10-3M) and the NO donor sodium nitroprusside (SNP; 10-5M), respectively. HpA structure and distensibility were determined by measuring lumen diameter and wall thickness of fully relaxed arterioles. Data are mean ± SEM and comparisons made using a one-way ANOVA with a post-hoc Bonferroni test. Results HpAs from PE rats dilated less when SK/IK channels were activated with NS309 compared to P and NP rats (55 ± 18% vs. 88 ± 2% and 90 ± 4%; p = 0.053). Activation of KIR with 15 mM K+ caused less dilation in HpAs from PE rats compared to P and NP rats, although this did not reach statistical significance (9 ± 8% vs. 61 ± 27% and 20 ± 11%; p = 0.13). NOS inhibition with L-NAME did not constrict any HpAs, suggesting there was no basal NO production. HpAs from PE rats were less sensitive to NO, with less reactivity to SNP compared to P and NP rats (22 ± 10% vs. 30 ± 10% and 38 ± 8%; p > 0.05). Structurally, lumen diameters were smaller in fully relaxed HpAs from PE rats than NP rats (Fig. 1), and vessel walls were thinner in PE and P rats compared to NP rats (7.7 ± 0.6 μm and 8.3 ± 0.7 μm vs. 11.5 ± 0.7 μm at 60 mmHg; p p Conclusion HpAs from PE rats had impaired dilatory responses, were less distensible, and underwent inward, hypotrophic remodeling making them structurally smaller than the NP and P states. This combination of impaired vasodilation and structural remodeling of HAs in PE could limit blood flow to the hippocampus during seizure, resulting in ischemic neuronal injury.

Two Automated Techniques for Carotid Lumen Diameter Measurement: Regional versus Boundary Approaches

The degree of stenosis in the carotid artery can be predicted using automated carotid lumen diameter (LD) measured from B-mode ultrasound images. Systolic velocity-based methods for measurement of LD are subjective. With the advancement of high resolution imaging, image-based methods have started to emerge. However, they require robust image analysis for accurate LD measurement. This paper presents two different algorithms for automated segmentation of the lumen borders in carotid ultrasound images. Both algorithms are modeled as a two stage process. Stage one consists of a global-based model using scale-space framework for the extraction of the region of interest. This stage is common to both algorithms. Stage two is modeled using a local-based strategy that extracts the lumen interfaces. At this stage, the algorithm-1 is modeled as a region-based strategy using a classification framework, whereas the algorithm-2 is modeled as a boundary-based approach that uses the level set framework. Two sets of databases (DB), Japan DB (JDB) (202 patients, 404 images) and Hong Kong DB (HKDB) (50 patients, 300 images) were used in this study. Two trained neuroradiologists performed manual LD tracings. The mean automated LD measured was 6.35±0.95mm for JDB and 6.20±1.35mm for HKDB. The precision-of-merit was: 97.4% and 98.0% w.r.t to two manual tracings for JDB and 99.7% and 97.9% w.r.t to two manual tracings for HKDB. Statistical tests such as ANOVA, Chi-Squared, T-test, and Mann-Whitney test were conducted to show the stability and reliability of the automated techniques.

Accuracy and robustness of a simple algorithm to measure vessel diameter from B-mode ultrasound images.

Measurement of changes in arterial vessel diameter can be used to assess the state of cardiovascular health, but the use of such measurements as biomarkers is contingent upon the accuracy and robustness of the measurement. This work presents a simple algorithm for measuring diameter from B-mode images derived from vascular ultrasound. The algorithm is based upon Gaussian curve fitting and a Viterbi search process. We assessed the accuracy of the algorithm by measuring the diameter of a digital reference object (DRO) and ultrasound-derived images of a carotid artery. We also assessed the robustness of the algorithm by manipulating the quality of the image. Across a broad range of signal-to-noise ratio and with varying image edge error, the algorithm measured vessel diameter within 0.7% of the creation dimensions of the DRO. This was a similar level of difference (0.8%) to when an ultrasound image was used. When SNR dropped to 18 dB, measurement error increased to 1.3%. When edge position was varied by as much as 10%, measurement error was well maintained between 0.68 and 0.75%. All these errors fall well within the margin of error established by the medical physics community for quantitative ultrasound measurements. We conclude that this simple algorithm provides consistent and accurate measurement of lumen diameter from B-mode images across a broad range of image quality.