Estimation Of Wall Thickness Research Articles

Decoupled Advection-Dispersion Method for Determining Wall Thickness of Slurry Trench Cutoff Walls

Low-permeability slurry trench cutoff walls are commonly constructed as barriers for containment of subsurface point-source pollution or as part of seepage-control systems on contaminated sites. A method to estimate wall thickness in slurry wall design is proposed based on decoupling the advective and dispersive components of contaminant fluxes through the wall. The relative error of the result obtained by the proposed method compared with that by an analytical solution was found to increase as the ratio of the specified breakthrough exit concentration (c*) to the source concentration (c0) increased. For c*/c0 of less than 0.1, which covers common practical situations, the relative error was not greater than 4% and was always conservative, indicating that the proposed method provides sufficient accuracy for design. For a given breakthrough criterion (i.e., c*/c0), the relative error was low for the scenarios having either a low or high column Peclet number, where either dispersion or advection dominates the contaminant migration, respectively, and the relative error was high for the scenario having an intermediate column Peclet number, in which case the coupling effect of advective and dispersive migrations is relatively high.

Estimation of bladder wall thickness at different areas with ultrasound and its relation to cystocele

Objective The aim was to verify our hypothesis that decreasing bladder wall thickness will facilitate ballooning of the bladder wall at this thin part that will be involved in a process of cystocele other than the last traditional reported factors. Patients and methods This prospective study included 80 female patients between 20 and 45 years of age who were divided into two groups. Group I: 40 women were normal (control group); 20 of them were married and 20 were virgins and Group II: Comprising 40 patients have clinical manifestations of cystocele. All underwent complete history taking, physical examination, translabial, and transabdominal ultrasound examination with measurement of anterior and posterior detrusor wall thickness (DWT); also multichannel urodynamic testing was done to diagnose if there is associated obstruction or not. Results In group I, the mean DWT in 20 virgin women was 3.28±0.79 at the anterior bladder wall and 2.72±0.77 at the posterior bladder wall by transabdominal ultrasound, whereas by translabial ultrasound it measured 3.34±0.83 at the anterior bladder wall and 2.62±0.94 at the posterior bladder wall. In 20 married women of the control group without cystocele the mean DWT was 2.85±0.72 and 2.70±0.75 at the anterior and the posterior bladder wall, respectively, by transabdominal ultrasound. Also, the mean DWT was 2.90±0.69 and 2.75±0.74 at the anterior and the posterior bladder wall, respectively, by translabial ultrasound. In group II the anterior and the posterior wall measured 2.95±0.95 and 2.25±0.73, respectively, by transabdominal ultrasound, while it measured 4.35±1.40 and 2.40±0.77, respectively, by translabial ultrasound. With obvious obstruction in group II, P det.Q max. was 29.18±7.54 whereas it was 18.10±13.40 in group I. An increased level of Q max was noticed in group I with a mean value of 25.73±8.56 whereas it was of a less value in group II (15.83±6.21). Conclusion Our findings verify our hypothesis that decreasing bladder wall thickness will facilitate ballooning of the bladder wall at this thin part. Moreover, an increase in intravesical pressure during micturition will form a pseudo-diverticulum of the bladder wall, which in turn had lost the scaffolding of the fascia and/or vaginal wall.

New methods for the geometrical analysis of tubular organs.

This paper presents new methods to study the shape of tubular organs. Determining precise cross-sections is of major importance to perform geometrical measurements, such as diameter, wall-thickness estimation or area measurement. Our first contribution is a robust method to estimate orthogonal planes based on the Voronoi Covariance Measure. Our method is not relying on a curve-skeleton computation beforehand. This means our orthogonal plane estimator can be used either on the skeleton or on the volume. Another important step towards tubular organ characterization is achieved through curve-skeletonization, as skeletons allow to compare two tubular organs, and to perform virtual endoscopy. Our second contribution is dedicated to correcting common defects of the skeleton by new pruning and recentering methods. Finally, we propose a new method for curve-skeleton extraction. Various results are shown on different types of segmented tubular organs, such as neurons, airway-tree and blood vessels.

Beam Diffraction Effects in the Backward Wave Regions of Viscoelastic Leaky Lamb Modes for Plate Transmission at Normal Incidence.

Plane-wave theory for fluid-embedded isotropic plates is often used in ultrasonic guided-wave applications, and to estimate wall thickness, corrosion, or sound velocities in plates and pipes. In such structures, measured ultrasonic transmission through the solid material is affected by acoustic beam diffraction effects, and the results may deviate from plane-wave descriptions, which are insufficient to describe the complex effects that occur. When exciting a fluid-embedded steel plate with a pulsed ultrasonic beam at normal incidence, resonance frequency downshift, axial sound pressure level increase, and beam narrowing have been observed, for measured resonance peaks in the frequency regions of certain leaky Lamb mode branches of the plate. In the ranges of other leaky Lamb mode branches, the observed effects are different. Measurements, finite element, and angular spectrum modeling are used to indicate a close connection between these beam diffraction phenomena and the backward wave characteristics of certain leaky Lamb mode pairs, in the frequency and Poisson's ratio regions around coincidence of two Lamb mode cutoff frequencies of similar symmetry. In particular, such observations made for the steel plate's fundamental thickness-extensional (TE) mode appear to be caused by acoustic beam excitation of the backward wave regions of the S-2vl and S2vl leaky Lamb modes.

Estimation of emission cone wall thickness of Jupiter’s decametric radio emission using stereoscopic STEREO/WAVES observations

Aims. Stereoscopic observations by the WAVES instrument onboard two STEREO spacecraft have been used with the aim of estimating wall thickness of an emission cone of Jovian decametric radio emission (DAM). Methods. Stereoscopic observations provided by STEREO-A and -B facilitate unambiguous recognition of the Jovian DAM in observed dynamic spectra as well as identification of its components (Io DAM or non-Io DAM). The dynamic spectra of radio emissions recorded by STEREO/WAVES have been analyzed using the method of cross-correlation of the radio dynamic spectra. Results. Altogether, 139 radio events, in particular 91 Io- and 48 non-Io-related radio events were observed. The averaged width of the emission cone wall for Io-DAM as well as for non-Io DAM is about 1.1° ± 0.2°. These results are in agreement with previous findings.

Biomechanical Characterization of Ascending Aortic Aneurysms

Ascending thoracic aortic aneurysms (ATAAs) are a silent disease, ultimately leading to dissection or rupture of the arterial wall. There is a growing consensus that diameter information is insufficient to assess rupture risk, whereas wall stress and strength provide a more reliable estimate. The latter parameters cannot be measured directly and must be inferred through biomechanical assessment, requiring a thorough knowledge of the mechanical behaviour of the tissue. However, for healthy and aneurysmal ascending aortic tissues, this knowledge remains scarce. This study provides the geometrical and mechanical properties of the ATAA of six patients with unprecedented detail. Prior to their ATAA repair, pressure and diameter were acquired non-invasively, from which the distensibility coefficient, pressure-strain modulus and wall stress were calculated. Uniaxial tensile tests on the resected tissue yielded ultimate stress and stretch values. Parameters for the Holzapfel-Gasser-Ogden material model were estimated based on the pre-operative pressure-diameter data and the post-operative stress-stretch curves from planar biaxial tensile tests. Our results confirmed that mechanical or geometrical information alone cannot provide sufficient rupture risk estimation. The ratio of physiological to ultimate wall stress seems a more promising parameter. However, wall stress estimation suffers from uncertainties in wall thickness measurement, for which our results show large variability, between patients but also between measurement methods. Our results also show a large strength variability, a value which cannot be measured non-invasively. Future work should therefore be directed towards improved accuracy of wall thickness estimation, but also towards the large-scale collection of ATAA wall strength data.

Wall thickness measurement using resonant phenomena of circumferential Lamb waves generated by plural transducer elements located evenly on girth

We present a novel method of measuring the pipe wall thickness using the resonance of the circumferential (C-) Lamb wave generated by a piezoelectric ring-shaped sensor (PS). The PS is a special device for an axially propagating torsional wave; however, the C-Lamb waves are generated simultaneously as spurious signals owing to the structure of the PS. Particularly under resonant conditions, the C-Lamb waves are dominantly generated, distorting the axially propagating wave. In this method, these troublesome spurious signals are used effectively for the measurement of the wall thickness under the PS location that is a dead zone of the PS itself. The method can compensate for its drawback, namely, the dead zone problem, without using additional instruments. In this study, the mechanisms of the generation and resonance of the C-Lamb waves were first explained. Secondly, the principle of the wall thickness estimation utilizing the resonance of the C-Lamb waves was proposed. Finally, experimental verifications were carried out. The estimated wall thicknesses agreed very well (maximum 1.5% error) with those measured by a micrometer caliper under suitable resonant conditions.

Using imaging ToF‐SIMS data to determine the cell wall thickness of fibers in wood

Here, we demonstrate the use of time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) imaging data for estimation of cell wall thickness in wood samples. Current research in forest biotechnology focuses on transgenic trees with wood properties tailored to specific applications. Appropriate analytical methods to characterize the very heterogeneous wood material are constantly being developed and improved. Chemical imaging of wood by ToF‐SIMS represents an interesting tool for this purpose with many applications. In addition to wood chemistry, the impact of specific genetic modifications on wood anatomy needs to be assessed. Cell wall thickness is an important anatomical parameter that among others is used for assessing biomass accumulation. We developed a strategy to estimate cell wall thickness from ToF‐SIMS images and implemented it in the open source programming language ‘R’. In brief, random lines are projected over the black and white mask of a ToF‐SIMS image, and length values of all line sections that cut across a cell wall are collected. After enough iteration, the shortest values of the obtained count distribution represent the crossing sections normal to the cell walls, hence cell wall thickness. Compared with conventional light microscopy image analysis, TOF‐SIMS data offers many advantages such as submicron resolution and additional spectral information for automated annotation of distinct anatomical features. This work underlines the importance of SIMS imaging for studies of wood chemistry and anatomy and provides a new approach to obtain an important wood anatomical parameter from ToF‐SIMS data. © 2014 The Authors. Surface and Interface Analysis published by John Wiley & Sons, Ltd.

Accurate Measurement of Small Airways on Low-Dose Thoracic CT Scans in Smokers

Partial volume averaging and tilt relative to the scan plane on transverse images limit the accuracy of airway wall thickness measurements on CT scan, confounding assessment of the relationship between airway remodeling and clinical status in COPD. The purpose of this study was to assess the effect of partial volume averaging and tilt corrections on airway wall thickness measurement accuracy and on relationships between airway wall thickening and clinical status in COPD. Airway wall thickness measurements in 80 heavy smokers were obtained on transverse images from low-dose CT scan using the open-source program Airway Inspector. Measurements were corrected for partial volume averaging and tilt effects using an attenuation- and geometry-based algorithm and compared with functional status. The algorithm reduced wall thickness measurements of smaller airways to a greater degree than larger airways, increasing the overall range. When restricted to analyses of airways with an inner diameter < 3.0 mm, for a theoretical airway of 2.0 mm inner diameter, the wall thickness decreased from 1.07 ± 0.07 to 0.29 ± 0.10 mm, and the square root of the wall area decreased from 3.34 ± 0.15 to 1.58 ± 0.29 mm, comparable to histologic measurement studies. Corrected measurements had higher correlation with FEV₁, differed more between BMI, airflow obstruction, dyspnea, and exercise capacity (BODE) index scores, and explained a greater proportion of FEV1 variability in multivariate models. Correcting for partial volume averaging improves accuracy of airway wall thickness estimation, allowing direct measurement of the small airways to better define their role in COPD.

Image-Domain Estimation of Wall Parameters for Autofocusing of Through-the-Wall SAR Imagery

Estimation of the basic parameters, wall thickness and dielectric constant, is important in through-the-wall radar imaging. Ambiguities in wall characteristics will degrade the image focusing quality of synthetic-aperture radar. In order to obtain a quick and precise estimation of wall parameters, an equivalent propagation model of an electromagnetic wave in the air-wall-air medium is first developed in this paper. According to the developed propagation model, two filter-based approaches, denoted respectively as the echo-domain-filter-based method and the image-domain-filter-based method, are proposed to estimate wall thickness and dielectric constant by adjusting the two corresponding parameters of the echo-domain filter or the image-domain filter to obtain the best focusing quality of behind-the-wall targets. The processing schemes of the two methods show that the image-domain-filter-based method is more efficient because it does not involve imaging processing in each adjustment. Moreover, the image-domain-filter-based method is accelerated by reducing the dimension of searching space to better the computational efficiency further. Simulation results show that the proposed accelerating image-domain-filter-based method can provide quick and precise estimation of wall parameters.

Predictive value of resistive index, detrusor wall thickness and ultrasound estimated bladder weight regarding the outcome after transurethral prostatectomy for patients with lower urinary tract symptoms suggestive of benign prostatic obstruction

To evaluate the value of three parameters from preoperative ultrasonography in predicting the outcome of transurethral prostatectomy in patients with lower urinary tract symptoms suggestive of benign prostatic obstruction. A total of 239 patients with lower urinary tract symptoms suggestive of benign prostatic obstruction entering our department for surgical therapy were prospectively recruited. All of them underwent both ultrasound and urodynamics before receiving standard transurethral prostatectomy by the same team of surgeons. For 202 patients, 6-month follow-up data were available after the surgery, including the International Prostate Symptom Score, the Quality of Life score and the maximum flow rate. Preoperative data stratified by different degree of recovery were compared and the influence of ultrasound parameters on the surgical outcome was analyzed by using logistic regression and receiver-operator characteristic curve analyses. Baseline transitional zone index, intravesical prostatic protrusion, resistive index, detrusor wall thickness and ultrasonic estimation of bladder weight were significantly different between patients with an effective outcome and those with an ineffective outcome (P < 0.05). Resistive index, detrusor wall thickness and ultrasonic estimation of bladder weight were selected as independent factors correlated with the efficacy of transurethral prostatectomy by logistic regression (P < 0.05). All three factors had adequate area under receiver-operator characteristic curve with resistive index having the largest area (0.816, 95% CI 0.759-0.874). The combined positive predictive value in effective surgical outcome of resistive index, detrusor wall thickness and ultrasonic estimation was 96.3%. Resistive index, detrusor wall thickness and ultrasonic estimation adequately predict the outcome of transurethral prostatectomy. Measuring these parameters by preoperative ultrasound might aid in determining the need for surgical intervention.

Noninvasive monitoring of cardiac function in a chronic ischemic heart failure model in the rat: Assessment with tissue Doppler and non-Doppler 2D strain echocardiography

ObjectivesFeasibility of noninvasive monitoring of cardiac function after surgically induced ischemic cardiomyopathy with tissue Doppler and non-Doppler 2D strain echocardiography in rats.BackgroundThe optimal method for quantitative assessment of global and regional ventricular function in rats with chronic heart failure for research purposes remains unclear.Methods20 rats underwent suture ligation of the left anterior descending coronary artery via a left thoracotomy to induce ischemic cardiomyopathy. Echocardiographic examination with estimation of left ventricular wall thickness, diameters, fractional shortening, ejection fraction, wall velocities as well as radial strain were performed before and 4 weeks after surgery.ResultsMean LVEF decreased from 70 ± 6% to 40 ± 8% (p < 0.0001) one month after the operation. LVEDD increased from 7 ± 1 mm to 9 ± 1 mm (p < 0.0001), systolic anterior velocity decreased from 0.79 ± 0.25 cm/s to 0.18 ± 0.19 cm/s (p < 0.0001). Radial 2D strain was significantly reduced after myocardial infarction of the septal (18.2 ± 6.6% vs 7.0 ± 5.9%, p < 0.001), anteroseptal (17.3 ± 5.2% vs 4.6 ± 3.0%, p < 0.0001), anterior (18.9 ± 5.9% vs 5.6 ± 2.5%, p < 0.0001), lateral (21.4 ± 4.9% vs 8.1 ± 3.5%, p < 0.0001) as well as posterior myocardial segments (19.3 ± 5.2% vs 15.4 ± 5.5%, p < 0.01). Inferior segments (19.2 ± 7.9% vs 17.8 ± 7.9%, ns) did not change at all.ConclusionIt is feasible to assess dimensions, global function, and regional contractility with echocardiography in rats suffering from chronic heart failure after myocardial infarction. Particularly regional function can be exactly evaluated if tissue Doppler and 2D strain is used.

Novel biomarkers for overactive bladder

Biomarkers constitute any objectively measurable indicator of a biological process. The classic biomarker used in the diagnosis of overactive bladder (OAB) has been detrusor overactivity, which is assessed urodynamically. In the search for a reliable, noninvasive alternative to urodynamics, interest has focused on genetic, imaging, and urinary factors. Along with other cytokines detectable in urine, prostaglandin E2 and nerve growth factor are indicators of low-grade inflammation. Although they correlate with OAB symptom severity, they have not been shown to have independent prognostic benefit. Imaging biomarkers have been investigated since the earliest days of video urodynamics. Despite extensive research on the ultrasonographic estimation of bladder wall thickness, further standardization of the technique is required before conclusions can be reached regarding diagnostic accuracy. Genetic factors contribute approximately half of the total risk for urgency incontinence. Functional polymorphisms of the cytochrome P450 IID6 gene significantly alter the metabolism of some commonly used anticholinergic drugs, but no genetic loci that influence risk of OAB have been definitively identified. The first genome-wide association studies for OAB are in progress, and should identify new susceptibility genes. Although current putative biomarkers correlate with OAB severity, much future work is required to assess their prognostic value, and establish their role in clinical practice.

Determination of the elastic properties of single microcapsules using micromanipulation and finite element modeling

Finite element modeling (FEM) has been used to simulate the compression of single elastic core–shell capsules between two parallel plates. FEM allows characterizing the compressions at deformations beyond the wall thickness, when both bending and stretching contribute to the force resisting compression. Due to the incorporation of bending effects, the force deformation profiles of capsules with the same elastic modulus E depend on the wall thickness to capsule radius ratio ( h/r). A model is presented that enables the (i) calculation of h/r from the individual compression force profiles at fractional deformations lower than 0.1, thus applicable for brittle capsules and for elastic–plastic capsules and (ii) calculation of Eh by comparison with FEM data at that h/r. Thus, the model allows the determination of E from compression data alone, as the wall thickness is also determined. The compression of melamine–formaldehyde capsules with a hexyl salicylate core using a micromanipulation technique is given as an example of the application of the model. The estimated wall thickness value, found to be independent of the capsule size, is in excellent agreement with transmission electron microscopy measurements.

J042012 集束型空気超音波センサーによる円周Lamb波の効率的励起メカニズムと減肉計測への応用([J04201]超音波計測・解析法の新展開(1))

Efficient transduction of a circumferential (C-) Lamb wave by a pair of noncontact air-coupled ultrasonic transducers (NAUT) was presented. A line focus type (LFT-) of the NAUT was employed for the efficient transduction. Characteristics of the LFT-NAUT were theoretically and experimentally shown in comparison to those of the conventional plane type (CPT-) NAUT. The efficiency of the C-Lamb wave generated and detected by the LFT-NAUT took about 20 times higher than that by the CPT-NAUT. As for an application of the C-Lamb wave generated by the LFT-NAUT, a novel method of an accurate estimation of pipe wall thickness was introduced and evaluated with a theoretical model. It was confirmed that the averaged error between the experiments and the theoretical model was at less than 10 μm.

Validation of live animal ultrasonic measurements of body composition in market lambs

Market lambs from the state fair of Virginia (n = 172) were ultrasonically evaluated by 4 scan technicians and 3 image interpreters to determine accuracy of ultrasonic estimates of loin muscle area (ULMA), backfat thickness (UBF), and body wall thickness (UBW). Lambs were initially scanned at the preferred magnification setting of each technician; 2 chose 1.5x and 2 chose 2.0x. Lambs were then scanned a second time for ULMA and UBF with machine magnification settings changed from 1.5 to 2.0x, or vice versa, midway through the second scan. Lambs were then slaughtered, and analogous measurements [carcass loin muscle area, carcass backfat thickness, and carcass body wall thickness (CBW)] were recorded on chilled carcasses. Pooled, residual correlation coefficients within technicians and interpreters between ultrasonic measurements from the first scan and carcass measurements were 0.66 for loin muscle area, 0.78 for backfat thickness, and 0.73 for body wall thickness, but were reduced to 0.43, 0.69, and 0.50, respectively, by inclusion of linear effects of carcass weight in the model. Mean bias for technicians and interpreters ranged from -1.30 to -2.66 cm(2) for loin muscle area, -0.12 to -0.17 cm for backfat thickness, and 0.14 to -0.03 cm for body wall thickness; prediction errors ranged from 1.86 to 2.22 cm(2), 0.12 to 0.14 cm, and 0.35 to 0.38 cm, respectively. Pooled correlations between repeated measures were 0.67 for ULMA, 0.79 for UBF, and 0.68 for UBW at the same magnification and 0.73 for ULMA and 0.76 for UBF across different magnification settings. Mean differences between repeated measures were more variable among technicians and interpreters than statistics comparing ultrasound to carcass measures. Standard errors of repeatability ranged from 1.61 to 2.45 cm(2) for ULMA, 0.07 to 0.11 cm for UBF, and 0.36 to 0.42 cm for UBW. The effect of changing magnification setting on technician and interpreter repeatability was small for UBF and ULMA. The accuracy of prediction of CBW from UBW was similar to that achieved for backfat thickness; further assessment of the value of ultrasonic measurements of body wall thickness in lambs is warranted. These results indicate that ultrasound scanning can reliably predict carcass loin muscle area and backfat thickness in live lambs and, accordingly, has value in selection programs to improve composition. Development of certification standards for US lamb ultrasound technicians based on results of this study and others is proposed.

Semiautomatic vessel wall detection and quantification of wall thickness in computed tomography images of human abdominal aortic aneurysms

Quantitative measurements of wall thickness in human abdominal aortic aneurysms (AAAs) may lead to more accurate methods for the evaluation of their biomechanical environment. The authors describe an algorithm for estimating wall thickness in AAAs based on intensity histograms and neural networks involving segmentation of contrast enhanced abdominal computed tomography images. The algorithm was applied to ten ruptured and ten unruptured AAA image data sets. Two vascular surgeons manually segmented the lumen, inner wall, and outer wall of each data set and a reference standard was defined as the average of their segmentations. Reproducibility was determined by comparing the reference standard to lumen contours generated automatically by the algorithm and a commercially available software package. Repeatability was assessed by comparing the lumen, outer wall, and inner wall contours, as well as wall thickness, made by the two surgeons using the algorithm. There was high correspondence between automatic and manual measurements for the lumen area (r = 0.978 and r = 0.996 for ruptured and unruptured aneurysms, respectively) and between vascular surgeons (r = 0.987 and r = 0.992 for ruptured and unruptured aneurysms, respectively). The authors' automatic algorithm showed better results when compared to the reference with an average lumen error of 3.69%, which is less than half the error between the commercially available application Simpleware and the reference (7.53%). Wall thickness measurements also showed good agreement between vascular surgeons with average coefficients of variation of 10.59% (ruptured aneurysms) and 13.02% (unruptured aneurysms). Ruptured aneurysms exhibit significantly thicker walls (1.78 +/- 0.39 mm) than unruptured ones (1.48 +/- 0.22 mm), p = 0.044. While further refinement is needed to fully automate the outer wall segmentation algorithm, these preliminary results demonstrate the method's adequate reproducibility and low interobserver variability.

Kernel regression methods for the prediction of wood properties of Pinus taeda using near infrared spectroscopy

Near infrared diffuse reflectance spectra collected in 10-mm sections were used for the estimation of air-dry density (AD), microfibril angle (MFA), stiffness (MOE), tracheid coarseness (COARS), and tracheid wall thickness (WTHICK) in wood radial strip samples obtained at breast height (1.4 m) from 60 Pinus taeda trees. Calibration models were developed using traditional partial least squares (PLS) and kernel regression. The kernel methods included radial basis functions-partial least squares (RBF-PLS) and least-squares support vector machines (LS-SVM). RBF-PLS and LS-SVM models outperformed PLS-CV calibrations in terms of fit statistics. MFA and MOE, two properties that exhibited nonlinearity, showed the most significant improvements compared to PLS. In terms of predictive ability RBF-PLS performed better than PLS for the prediction of MFA, MOE, and COARS. LS-SVM showed better prediction statistics in all cases, except for WTHICK that gave similar statistics compared to PLS and was superior to RBF-PLS. By adding statistically significant factors to the PLS regressions, it was possible to capture some of the nonlinear features of the data and improve the predictive ability of the PLS models.

Clinical Significance of Radiologic Characterizations in COPD

ABSTRACTCOPD is a heterogeneous disorder with clinical assessment becoming increasingly multidimensional. We hypothesized HRCT phenotype would strongly influence clinical outcomes including health status, exacerbation frequency, and BODE. COPD subjects were characterized via the SF-12, SGRQ, MMRC, physiologic testing, and standardized volumetric chest HRCT. Visual semi-quantitative estimation of bronchial wall thickness (VBT) and automated quantification of emphysema percent and bronchial wall thickness were generated. Multivariate modeling compared emphysema severity and airway abnormality with clinical outcome measures. Poisson models were used to analyze exacerbation frequency. SGRQ and SF-12 physical component scores were influenced by FEV1% predicted, emphysema percent, and VBT. VBT scores > 2 (scale 0–48) were associated with increased exacerbation frequency (p = 0.009) in the preceding year adjusting for age, gender, emphysema percent, smoking history and FEV1% predicted, although this effect was attenuated by age. Emphysema percent correlated with total BODE score in unadjusted (r = 0.73; p < 0.0001) and adjusted (p < 0.0001) analyses and with BODE individual components. HRCT provides unique COPD phenotyping information. Radiographic quantification of emphysema and bronchial thickness are independently associated with SGRQ and physical component score of the SF-12. Bronchial thickness but not emphysema is associated with exacerbation frequency, whereas emphysema is a stronger predictor of BODE and its systemic components MMRC, 6MWT, and BMI. Future research should clarify whether CT parameters complement BODE score in influencing survival.

Three-Dimensional Geometrical Characterization of Abdominal Aortic Aneurysms: Image-Based Wall Thickness Distribution

The clinical assessment of abdominal aortic aneurysm (AAA) rupture risk is based on the quantification of AAA size by measuring its maximum diameter from computed tomography (CT) images and estimating the expansion rate of the aneurysm sac over time. Recent findings have shown that geometrical shape and size, as well as local wall thickness may be related to this risk; thus, reliable noninvasive image-based methods to evaluate AAA geometry have a potential to become valuable clinical tools. Utilizing existing CT data, the three-dimensional geometry of nine unruptured human AAAs was reconstructed and characterized quantitatively. We propose and evaluate a series of 1D size, 2D shape, 3D size, 3D shape, and second-order curvature-based indices to quantify AAA geometry, as well as the geometry of a size-matched idealized fusiform aneurysm and a patient-specific normal abdominal aorta used as controls. The wall thickness estimation algorithm, validated in our previous work, is tested against discrete point measurements taken from a cadaver tissue model, yielding an average relative difference in AAA wall thickness of 7.8%. It is unlikely that any one of the proposed geometrical indices alone would be a reliable index of rupture risk or a threshold for elective repair. Rather, the complete geometry and a positive correlation of a set of indices should be considered to assess the potential for rupture. With this quantitative parameter assessment, future research can be directed toward statistical analyses correlating the numerical values of these parameters with the risk of aneurysm rupture or intervention (surgical or endovascular). While this work does not provide direct insight into the possible clinical use of the geometric parameters, we believe it provides the foundation necessary for future efforts in that direction.