Intraobserver Coefficient Of Variation Research Articles

Reproducibility of Optical Coherence Tomography Measurements in Children

To determine the interobserver and intraobserver reproducibility of a Fourier-domain optical coherence tomography device (Cirrus HD OCT; Carl Zeiss Meditec, Dublin, California, USA) in normal pediatric eyes. Prospective cross-sectional study. One hundred healthy children were recruited prospectively and consecutively. Only 1 randomly chosen eye per subject was included in the study. The eye underwent 3 scans centered on the optic disc and another 3 scans centered on the macula that were acquired by a single operator. A fourth examination was performed by a second operator. Interobserver and intraobserver reproducibility were described by intraclass correlation coefficients (ICCs) and coefficients of variation (COVs). The mean age was 9.15 years (range, 6.22 to 11.31 years; standard deviation, 1.05 years). Mean retinal nerve fiber layer thickness was 99.53 μm (standard deviation, 10.10 μm), and mean macular thickness was 282.91 μm (standard deviation, 11.83 μm). All the parameters evaluated were highly reproducible. Intraobserver COVs of the retinal nerve fiber layer measurements ranged from 2.24% to 5.52%, and the COV of macular thickness was 0.97%. The intraclass correlation coefficient was greater than 0.8 for all the parameters. The interobserver COV ranged from 2.23% to 5.18%, and the COV of macular thickness was 0.82%. In all the evaluated parameters, the intraclass correlation coefficient was more than 0.75. Repeatability was slightly better in children older than 10 years than in children younger than 9 years. Retinal nerve fiber layer and macular measurements obtained by Fourier-domain optical coherence tomography showed good repeatability for healthy eyes in the pediatric population. Cirrus HD OCT examinations of the retina are reliable in children.

Precision of High Definition Spectral-Domain Optical Coherence Tomography for Measuring Central Corneal Thickness

This study was intended to assess the reliability of central corneal thickness (CCT) measurements using Cirrus high-definition optical coherence tomography (HD-OCT) in healthy subjects and its accuracy compared with ultrasonic pachymetry. Seventy-seven consecutive subjects were recruited for evaluating repeatability, and agreement between two examiners. To analyze repeatability, one examiner measured 77 eyes four times in succession. To study agreement between two observers, a second independently trained examiner obtained another CCT measurement. We also measured eyes in a subgroup of 20 patients using standard ultrasonic pachymetry. Within-subject standard deviation (S(w)), coefficient of variation (CV), limits of agreement (LoA), and intraclass correlation coefficient (ICC) data were obtained. For repeatability, the S(w) and precision (1.96 × S(w)) were 4.86 and 9.52 μm, respectively. Intraobserver CV was 0.89% and the ICC was 0.98 (95% confidence interval [CI], 0.97-0.99). For agreement between two examiners, the S(w) and precision were 7.58 and 14.85 μm, respectively; the CV was 1.40%. The mean difference between observers was -0.13 μm (95% CI, -1.85 to 1.58; P = 0.87). The width of the LoA was 29.64 μm. Median difference between Cirrus HD-OCT and ultrasound CCT measurements was -4.5 μm (interquartile range, -7.0-0.0; P = 0.04). Cirrus HD-OCT provides repeatable CCT measurements, good agreement between two independently trained examiners, and its systematic bias compared to ultrasonic pachymetry is clinically negligible. Therefore, research laboratories and eye clinics using Cirrus HD-OCT as a diagnostic imaging method, can also benefit from a reliable noncontact pachymeter when counseling patients with glaucoma and those undergoing corneal and refractive surgeries.

Reproducibility of brachial artery flow-mediated and glyceryl trintrate-mediated dilatation by 3Tesla CMR

Intra-observer and inter-study reproducibility of brachial artery flow-mediated dilatation (FMD) and glyceryl trintrate (GTN)-mediated dilatation by CMR at 3Tesla were assessed. Coefficients of variation (CoV) were calculated using the root mean square method. The intra-observer CoV, assessed in 15 subjects, was 15% for both FMD and GTN response. The inter-study CoV, assessed in 17 subjects, was 24% for FMD and 34% for GTN response.

Three-dimensional lung tumor segmentation from x-ray computed tomography using sparse field active models

Manual segmentation of lung tumors is observer dependent and time-consuming but an important component of radiology and radiation oncology workflow. The objective of this study was to generate an automated lung tumor measurement tool for segmentation of pulmonary metastatic tumors from x-ray computed tomography (CT) images to improve reproducibility and decrease the time required to segment tumor boundaries. The authors developed an automated lung tumor segmentation algorithm for volumetric image analysis of chest CT images using shape constrained Otsu multithresholding (SCOMT) and sparse field active surface (SFAS) algorithms. The observer was required to select the tumor center and the SCOMT algorithm subsequently created an initial surface that was deformed using level set SFAS to minimize the total energy consisting of mean separation, edge, partial volume, rolling, distribution, background, shape, volume, smoothness, and curvature energies. The proposed segmentation algorithm was compared to manual segmentation whereby 21 tumors were evaluated using one-dimensional (1D) response evaluation criteria in solid tumors (RECIST), two-dimensional (2D) World Health Organization (WHO), and 3D volume measurements. Linear regression goodness-of-fit measures (r(2) = 0.63, p < 0.0001; r(2) = 0.87, p < 0.0001; and r(2) = 0.96, p < 0.0001), and Pearson correlation coefficients (r = 0.79, p < 0.0001; r = 0.93, p < 0.0001; and r = 0.98, p < 0.0001) for 1D, 2D, and 3D measurements, respectively, showed significant correlations between manual and algorithm results. Intra-observer intraclass correlation coefficients (ICC) demonstrated high reproducibility for algorithm (0.989-0.995, 0.996-0.997, and 0.999-0.999) and manual measurements (0.975-0.993, 0.985-0.993, and 0.980-0.992) for 1D, 2D, and 3D measurements, respectively. The intra-observer coefficient of variation (CV%) was low for algorithm (3.09%-4.67%, 4.85%-5.84%, and 5.65%-5.88%) and manual observers (4.20%-6.61%, 8.14%-9.57%, and 14.57%-21.61%) for 1D, 2D, and 3D measurements, respectively. The authors developed an automated segmentation algorithm requiring only that the operator select the tumor to measure pulmonary metastatic tumors in 1D, 2D, and 3D. Algorithm and manual measurements were significantly correlated. Since the algorithm segmentation involves selection of a single seed point, it resulted in reduced intra-observer variability and decreased time, for making the measurements.

Endometrial cell counts in recurrent miscarriage: a comparison of counting methods

Studies of uterine natural killer (uNK) cells require reliable measurements of uNK cell density among diverse endometrial tissue. The aim of this study was to compare cell counting manually with two computer-aided methods based on a public domain software package, ImageJ. Immunohistochemistry (IHC) of CD56(+) uNK cells was performed on endometrium from recurrent miscarriage patients. Numbers of stromal cells per high-power field (HPF) were counted by two observers using: (i) manual tally counter and graticule; (ii) ImageJ 'point picker' tool; and (iii) ImageJ 'particle analysis' tool. Coefficients of variation (CV) and Bland-Altman plots were used to evaluate interobserver differences. Evaluation of %uNK using ImageJ particle analysis for stromal cell counts and point picker tool for uNK counts was undertaken. Point picker and particle analysis were significantly better than manual counting [interobserver CVs mean (standard deviation) 6.1% (3.3%); 4.7% (3.9%), 8.2% (6.5%), respectively]. Mean inter- and intra-observer CVs for %uNK were 10.3% (6.6%), 8.5% (4.9%) and 6.8% (4.3%), respectively. Bland-Altman analysis revealed no systematic differences in cell counts with the number of cells in the image for each method. Compared to manual cell counting, computer-aided image analysis yields more reproducible results for the assessment of uNK cells density using IHC.

Fourier analysis of STimulated echoes (FAST) for the quantitative analysis of left ventricular twist

To validate a novel method for the rapid and facile quantification of left ventricular (LV) twist from tagged magnetic resonance images and demonstrate the potential clinical utility in a series of 20 healthy volunteers. Cardiac magnetic resonance imaging (MRI) short-axis images were acquired with tissue tagging in 20 healthy subjects and six canines. The tagged images were processed using a novel Fourier Analysis of the STimulated echoes (FAST) method, which uses a series of Fourier-space operations to measure LV twist with limited user interaction. A subset of eight healthy subjects and the canine data were compared to results from previously validated "gold standard" software (FindTags). Interobserver and intraobserver coefficients of variation (CV(INTER) and CV(INTRA) ), linear regression, and Bland-Altman analyses were used to assess agreement between observers and methods. CV(INTRA) for peak systolic twist (2.9% and 2.6%) and CV(INTER) (4.3% and 4.2%) were all small. Linear regression analysis of the FAST and FindTags twist values indicated very good agreement in healthy subjects (R = 0.91) and in canines (R = 0.95). Bland-Altman comparison of the FAST and FindTags twist results indicated excellent agreement in healthy subjects (bias of -0.5°, 95% confidence intervals (-4.3°, 4.3°)) and canines (bias of 0.2°, 95% confidence intervals (-2.7°, 3.1°)). Peak systolic twist in healthy subjects averaged 10.5 ± 1.9° degrees. The FAST method for quantifying LV twist produces results that are not significantly different from the current "gold standard" in a fraction of the user interaction time and has demonstrated feasibility in human subjects.

A grid overlay framework for analysis of medical images and its application to the measurement of stroke lesions

To create and evaluate an interactive software tool for measuring imaging data in situations where hand-drawn region-of-interest measurements are unfeasible, for example, when the structure of interest is patchy with ill-defined boundaries. An interactive grid overlay software tool was implemented that enabled coding of voxels dependent on their imaging appearance with a series of user-defined classes. The Grid Analysis Tool (GAT) was designed to automatically extract quantitative imaging data, grouping the results by tissue class. Inter- and intra-observer reproducibility was evaluated by six observers of various backgrounds in a study of acute stroke patients. The software tool enabled a more detailed classification of the stroke lesion than would be possible with a region-of-interest approach. However, inter-observer coefficients of variation (CVs) were relatively high, reaching 70% in "possibly abnormal" tissue and around 15-20% in normal appearing tissues, while intra-observer CVs were no more than 13% in "possibly abnormal" tissue and generally less than 1% in normal-appearing tissues. The grid-overlay method overcomes some of the limitations of conventional Region Of Interest (ROI) approaches, providing a viable alternative for segmenting patchy lesions with ill-defined boundaries, but care is required to ensure acceptable reproducibility if the method is applied by multiple observers. Computer software developed to overcome limitations of conventional regions of interest measurements • This software is suitable for patchy lesions with ill-defined borders • Allows a more detailed assessment of imaging data.

Surface area measurement using rendered three‐dimensional ultrasound imaging: an in‐vitro phantom study

Cranial sutures and fontanelles can be reliably demonstrated using three-dimensional (3D) ultrasound with rendering. Our objective was to assess the repeatability and validity of fontanelle surface area measurement on rendered 3D images. This was an in-vitro phantom validation study. Four holes, representing fontanelles, were cut on a flat vinyl tile. The phantom was scanned in a test-tank by two sonographers, at four different depths and using two different 3D sweep directions. The surface areas were measured on scan images and also directly from the phantom for comparison. Coefficients of variation (CVs), intraclass correlation coefficients (ICCs) and Bland-Altman plots were used for repeatability analysis. Validity was expressed as the percentage difference of the measured area from the true surface area. Validity of measurement was satisfactory with a mean percentage difference of - 5.9% (median = - 3.5%). The 95% limits of agreement were - 23.9 to 12.1%, suggesting that random error is introduced during image generation and measurement. Repeatability of caliper placement on the same image was higher (intraobserver CV = 1.6%, ICC = 0.999) than for measurement of a newly generated scan image (intraobserver CV = 5.5%, ICC = 0.992). Reduced accuracy was noted for the smallest shape tested. Surface area measurements on rendered 3D ultrasound images are accurate and reproducible in vitro.

Reproducibility of phantom-based quality assurance parameters in real-time ultrasound imaging

In a large radiological center, the ultrasound (US) quality assurance (QA) program involves several professionals. Although the operator and the parameters utilized can contribute to the results, the selected QA parameters should still reflect the quality of the US scanner, not the measuring process. To evaluate the reproducibility of recommended phantom-based US QA parameters in a realistic environment. Six sonographers measured six high-end US scanners with 20 transducers using a general purpose phantom. Every transducer was measured altogether seven times, using one frequency per transducer. The QA parameters studied were homogeneity, visualization depth, vertical and horizontal distance measurements, axial and lateral resolution, and the correct visibility of anechoic and high-contrast masses. The evaluation of the homogeneity was based on visual observations. Inter-observer interquartile ranges were computed for the grading of the masses. For the other QA parameters, the mean inter- and intra-observer coefficients of variation (CoV) were calculated. In addition, the symmetry of the reverberations when imaging air with a clean transducer was checked. The mean inter-observer CoVs were: visualization depth 11 ± 4%, vertical distance 1.7 ± 0.4%, horizontal distance 1.4 ± 0.6%, axial resolution 22 ± 7%, and lateral resolution 16 ± 8%. The mean intra-observer values were about half of these values with similar standard deviations. The visual evaluation of the homogeneity and the symmetry of the reverberations produced false-positive findings in 5% of the cases, but were found useful in detecting a defective transducer. The grading of the masses had mean interquartile ranges of 20-30% of the grading scale. The inter-observer variability in measuring phantom-based QA parameters can be relatively high. This should be considered when implementing a phantom-based QA protocol and evaluating the results.

T2 Mapping by Cardiovascular Magnetic Resonance Reveals Reduced T2 Times in Aortic Stenosis

Background: Aortic stenosis (AS) results in altered structural myocardial tissue characteristics including increased fibrosis and reduced capillary density. We hypothesised that quantitative T2-mapping would detect interstitial changes associated with severe AS and aimed to determine the variation and reproducibility of myocardial T2 times in patients with severe AS compared to healthy controls. Methods and results: A T2-prepared single-shot SSFP technique was used to generate three T2-weighted images with different T2 preparation times. T2 maps were generated by fitting the exponential decay curve using a linear 2-parameter model after logarithmic transformation. Mid-ventricular short axis and ventricular long-axis T2 maps were acquired using a 1.5 T scanner (Avanto, Siemens, Germany) and analysed using CMRTools (London, UK). Fifty-eight subjects (male, n = 31); age 62 (16), mean (SD); Severe AS, n = 26) were recruited to the study. Subjects with severe AS displayed lower T2 times than healthy controls (51.9 ms (1.6) vs. 54.4 ms (1.5), mean (SD); p = 0.01). The subjects underwent a second CMR which was reported by two blinded imaging experts. T2 measures were highly reproducible (inter-study Coefficient of Variation (CoV), 1%; intra-observer CoV, 1.2%; inter-observer CoV, 1.7%). Mid-wall LGE was observed in four subjects with AS, however, when patches of LGE were excluded from the regions of interest used to assess T2-time, the difference between healthy volunteers and AS patients persisted (p = 0.01). Conclusions: Quantitative myocardial T2 mapping in patients with severe AS demonstrates lower T2 times compared to healthy controls. T2 mapping is highly reproducible and holds promise for the characterisation of myocardial tissue in severe aortic stenosis.

Assessing left ventricular systolic function in shock: evaluation of echocardiographic parameters in intensive care

IntroductionAssessing left ventricular (LV) systolic function in a rapid and reliable way can be challenging in the critically ill patient. The purpose of this study was to evaluate the feasibility and reliability of, as well as the association between, commonly used LV systolic parameters, by using serial transthoracic echocardiography (TTE).MethodsFifty patients with shock and mechanical ventilation were included. TTE examinations were performed daily for a total of 7 days. Methods used to assess LV systolic function were visually estimated, "eyeball" ejection fraction (EBEF), the Simpson single-plane method, mean atrioventricular plane displacement (AVPDm), septal tissue velocity imaging (TDIs), and velocity time integral in the left ventricular outflow tract (VTI).ResultsEBEF, AVPDm, TDIs, VTI, and the Simpson were obtained in 100%, 100%, 99%, 95% and 93%, respectively, of all possible examinations. The correlations between the Simpson and EBEF showed r values for all 7 days ranging from 0.79 to 0.95 (P < 0.01). the Simpson correlations with the other LV parameters showed substantial variation over time, with the poorest results seen for TDIs and AVPDm. The repeatability was best for VTI (interobserver coefficient of variation (CV) 4.8%, and intraobserver CV, 3.1%), and AVPDm (5.3% and 4.4%, respectively), and worst for the Simpson method (8.2% and 10.6%, respectively).ConclusionsEBEF and AVPDm provided the best, and Simpson, the worst feasibility when assessing LV systolic function in a population of mechanically ventilated, hemodynamically unstable patients. Additionally, the Simpson showed the poorest repeatability. We suggest that EBEF can be used instead of single-plane Simpson when assessing LV ejection fraction in this category of patients. TDIs and AVPDm, as markers of longitudinal function of the LV, are not interchangeable with LV ejection fraction.

Intraobserver and interobserver repeatability of ocular components measurement in cataract eyes using a new optical low coherence reflectometer

The purpose of the study was to assess intraobserver and interobserver repeatability of eight ocular components measurement in cataract eyes using the optical low-coherence reflectometer Lenstar LS 900®. Five consecutive measurements of ocular components were taken by two examiners using the Lenstar. Components analyzed were: central corneal thickness, lens thickness, anterior chamber depth, axial length, retinal thickness, keratometry, white-to-white distance, and pupillometry. Within-subject standard deviation and the coefficient of variation were calculated for evaluation of intraobserver repeatability. Bland-Altman analysis was used for assessment of interobserver repeatability. Thirty-two eyes of 22 patients were included. For both observers, the smallest intraobserver coefficient of variation was obtained for axial length, while the largest was found for corneal steepest meridian position. Interobserver repeatability demonstrated less repeatable results for white-to-white distance and corneal steepest meridian position. Considering axial length and anterior chamber depth values, predicted refractive error was 0 ± 0.05 D and 0.02 ± 0.19 D respectively in 95% of observations. The Lenstar LS 900® evidenced excellent repeatability and observers´ independent results of all components analyzed except white-to-white distance and corneal steepest meridian position measurements. To the best of our knowledge, this is the first study on interobserver repeatability of optical low-coherence reflectometry in cataract eyes.

Assessment of renal allograft fibrosis by acoustic radiation force impulse quantification - a pilot study

Chronic allograft nephropathy characterized by interstitial fibrosis and tubular atrophy is a major cause of renal transplant failure. Acoustic radiation force impulse (ARFI) quantification is a promising noninvasive method for assessing tissue stiffness. We evaluated if the method could reveal renal transplant fibrosis. In a prospective study, 30 adult renal transplant recipients were included. ARFI quantification, given as shear wave velocity (SWV), of the renal cortex was performed by two observers. SWV was compared to grade of fibrosis (0-3) in biopsies. The median SWV was 2.8 m/s (range: 1.6-3.6), 2.6 m/s (range: 1.8-3.5) and 2.5 m/s (range: 1.6-3) for grade 0 (n = 12), 1 (n = 10) and grades 2/3 (n = 8) fibrosis respectively. SWV did not differ significantly in transplants without and with fibrosis (grade 0 vs. grade 1, P = 0.53 and grade 0 vs. grades 2/3, P = 0.11). The mean intraobserver coefficient of variation was 22% for observer 1 and 24% for observer 2. Interobserver agreement, expressed as intraclass correlation coefficient was 0.31 (95% CI: -0.03 to 0.60). This study does not support the use of ARFI quantification to assess low-grade fibrosis in renal transplants. ARFI quantification in its present stage of development has also high intra- and interobserver variation in renal transplants.

Assessment of Carotid Stiffness and Intima-Media Thickness From Ultrasound Data

Increased arterial stiffness and carotid intima-media thickness (IMT) are considered independent predictors of cardiovascular events. The aim of this study was to compare a system recently developed in our laboratory for automatic assessment of these parameters from ultrasound image sequences to a reference radio frequency (RF) echo-tracking system. Common carotid artery scans of 21 patients with cardiovascular risk factors and 12 healthy volunteers were analyzed by both devices for the assessment of diameter (D), IMT, and distension (DeltaD). In the healthy volunteers, analyses were repeated twice to evaluate intraobserver variability. Agreement was evaluated by Bland-Altman analysis, whereas reproducibility was expressed as a coefficient of variation (CV). Regarding the agreement between the two systems, bias values +/- SD were 0.060 +/- 0.110 mm for D, -0.006 +/- 0.039 mm for IMT, and -0.016 +/- 0.039 mm for DeltaD. Intraobserver CVs were 2% +/- 2% for D, 5% +/- 5% for IMT, and 6% +/- 6% for DeltaD with the RF echo-tracking system and 2% +/- 1% for D, 6% +/- 6% for IMT, and 8% +/- 6% for DeltaD with our automated system. Although B-mode-based devices are less precise than RF-based ones, our automated system has good agreement with the reference method and comparable reproducibility, at least when high-quality images are analyzed. Hence, this study suggests that the presented system based on image processing from standard ultrasound scans is a suitable device for measuring IMT and local arterial stiffness parameters in clinical studies.

Reproducibility of adenosine stress cardiovascular magnetic resonance in multi-vessel symptomatic coronary artery disease.

PurposeFirst-pass perfusion cardiovascular magnetic resonance (CMR) is increasingly being utilized in both clinical practice and research. However, the reproducibility of this technique remains incompletely evaluated, particularly in patients with severe coronary artery disease (CAD). The purpose of this study was to determine the inter-study reproducibility of adenosine stress CMR in patients with symptomatic multi-vessel CAD and those at low risk for CAD.MethodsTwenty patients (10 with CAD, 10 low risk CAD) underwent two CMR scans 8 ± 2 days apart. Basal, mid and apical left ventricular short axis slices were acquired using gadolinium 0.05 mmol/kg at peak stress (adenosine, 140 μ/kg/min, 4 min) and rest. Myocardial perfusion was evaluated qualitatively by assessing the number of ischemic segments, and semi-quantitatively by determining the myocardial perfusion reserve index (MPRi) using a normalized upslope method. Inter-study and observer reproducibility were assessed--the latter being defined by the coefficient of variation (CoV), which was calculated from the standard deviation of the differences of the measurements, divided by the mean. Additionally, the percentage of myocardial segments with perfect agreement and inter- and intra-observer MPRi correlation between studies, were also determined.ResultsThe CoV for the number of ischemic segments was 31% with a mean difference of -0.15 ± 0.88 segments and 91% perfect agreement between studies. MPRi was lower in patients with CAD (1.13 ± 0.21) compared to those with low risk CAD (1.59 ± 0.58), p = 0.02. The reproducibility of MPRi was 19% with no significant difference between patients with CAD and those with low risk CAD (p = 0.850). Observer reproducibility for MPRi was high: inter-observer CoV 9%, r = 0.93 and intra-observer CoV 5%, r = 0.94. For trials using perfusion CMR as an endpoint, an estimated sample size of 12 subjects would be required to detect a two-segment change in the number of ischemic segments (power 0.9, α 0.05).ConclusionsAdenosine stress CMR, by qualitative and semi-quantitative normalized upslope analyses are reproducible techniques in both patients with multi-vessel CAD and those without known CAD. The robust inter-study reproducibility of perfusion CMR supports its clinical and research application.

Macular Thickness Interoperator and Intraoperator Reproducibility in Healthy Eyes Using 7 Optical Coherence Tomography Instruments

To evaluate macular thickness measurement reproducibility using 6 new spectral-domain (SD) optical coherence tomography (OCT) devices and 1 time-domain OCT device Prospective, observational study. setting: Clinical practice. study population: Macular thickness was assessed in 18 randomly chosen consecutive eyes of 18 healthy volunteers by 2 masked operators using 6 SD OCT devices and 1 time-domain OCT device. main outcome measures: Intraoperator and interoperator reproducibility of OCT-measured central macular thickness. Mean macular thickness ranged from 172.77 to 272.87 microm. Intraobserver Intraclass coefficient correlation ranged from 0.75 to 0.96. Intraobserver coefficient of variation ranged from 0.44 to 2.75. In Bland-Altman analysis, interoperator mean difference ranged from 0.22 to -9.69. An analysis of variance used for repeated measurement was statistically significant for instruments (P < .001) and operators (P = .04), but not for instruments x operators (P = .32). The 7 OCT devices presented differing macular thickness measurement values; the lowest value was with Copernicus, and the highest was with Spectralis HRA+OCT (Heidelberg Engineering). The new generation of SD OCT devices has good intraoperator reproducibility, but the Spectralis presents the highest reproducibility together with the best interoperator agreement. The software, and in particular the algorithm, used is the most important factor regarding reproducibility differences in macular thickness measurement. The main result of our study is that macular thickness absolute value differs for each device. For this reason, the devices are not interchangeable.

Pulsed‐Wave Tissue Doppler and Color Tissue Doppler Echocardiography: Calibration with M‐Mode, Agreement, and Reproducibility in a Clinical Setting

Myocardial velocities can be measured with both pulsed-wave tissue Doppler (PWTD) and color tissue Doppler (CTD) echocardiography. We aimed to (A) to explore which of the two methods better approximates true tissue motion and (B) to examine the agreement and the reproducibility of the two methods in a routine clinical setting. For Study A, the displacements of 63 basal myocardial segments from 13 patients were examined with M-mode and compared with the velocity-time integral of PWTD and CTD velocities. For Study B, the basal lateral segments from 58 patients were examined with PWTD and CTD, and the peak myocardial velocities during systole (Sm), early diastole (Em), and late diastole (Am) were measured. Study A: CTD-based measurements of displacement were 12% lower than M-mode measurements (95% CI: -18%; -6%). PWTD velocity-time integrals measured at the outer edge of the spectral band were 40% higher (33%; 46%) than M-mode measurements. Study B: PWTD measurements of myocardial velocity were systematically higher than CTD measurements: Sm 7.51 versus 5.54, difference 1.97 +/- 1.41 cm/sec; Em 8.74 versus 6.86, difference 1.88 +/- 1.70 cm/sec; Am 7.46 versus 5.17, difference 2.29 +/- 1.82 cm/sec; P < 0.001 for all. Intraobserver coefficient of variation for Sm, Em, and Am were 6%, 12%, and 12% for PWTD, 14%, 13%, and 20% for CTD. CTD measures numerically smaller tissue velocities than PWTD, mostly due to an overestimation of true tissue motion by PWTD. The methods have good agreement and comparable reproducibility.

Sonographic Assessment of Facial HIV-Related Lypoatrophy

To investigate the utility of ultrasonography (US) for assessing and grading facial lypoatrophy (FLA) in patients with HIV. The social effect of FLA is huge and may reduce antiretroviral therapy adherence. Strategies for the early detection of FLA are crucial, because complete correction of FLA in late stages is unlikely. Fifty-two HIV-positive patients undergoing highly active antiretroviral therapy underwent US with nasogenian transversal scan using a high-frequency broadband transducer (5-17 MHz) to detect FLA. Intra- and interobserver variability were calculated to assess US reproducibility. Concerning FLA grading, patients were categorized in five clinical classes and four US classes. Our results regarding inter- and intraobserver coefficients of variation permit the validation of US as a reproducible technique (p<.001), and a high correlation between US and clinical classification was obtained, with complete concordance for more advanced FLA classes. The lack of a reference objective method to quantify subcutaneous fat is a major difficulty in measuring HIV-related FLA. Our results, in accordance with data from the literature, suggest that US is an ideal tool for assessing and grading FLA. Furthermore, US may be suitable for routine evaluation in HIV-infected patients for early detection of FLA and to select its optimal management.

Orthogonal polarization spectroscopy to detect mesenteric hypoperfusion

Orthogonal polarization spectral (OPS) imaging is used to assess mucosal microcirculation. We tested sensitivity and variability of OPS in the assessment of mesenteric blood flow (Qsma) reduction. University Animal Laboratory. In eight pigs, Qsma was reduced in steps of 15% from baseline; five animals served as controls. Jejunal mucosal microcirculatory blood flow was recorded with OPS and laser Doppler flowmetry at each step. OPS data from each period were collected and randomly ordered. Samples from each period were individually chosen by two blinded investigators and quantified [capillary density (number of vessels crossing predefined lines), number of perfused villi] after agreement on the methodology. Interobserver coefficient of variation (CV) for capillary density from samples representing the same flow condition was 0.34 (0.04-1.41) and intraobserver CV was 0.10 (0.02-0.61). Only one investigator observed a decrease in capillary density [to 62% (48-82%) of baseline values at 45% Qsma reduction; P = 0.011], but comparisons with controls never revealed significant differences. In contrast, reduction in perfused villi was detected by both investigators at 75% of mesenteric blood flow reduction. Laser Doppler flow revealed heterogeneous microcirculatory perfusion. Assessment of capillary density did not reveal differences between animals with and without Qsma reduction, and evaluation of perfused villi revealed blood flow reduction only when Qsma was very low. Potential explanations are blood flow redistribution and heterogeneity, and suboptimal contrast of OPS images. Despite agreement on the method of analysis, interobserver differences in the quantification of vessel density on gut mucosa using OPS are high.

A Reproducibility Study of a TDI-Based Method to Calculate Indices of Arterial Stiffness

The aim of the study was to investigate the reproducibility of estimation of Young’s modulus E and pressure strain elastic modulus Ep, derived from a tissue Doppler imaging (TDI) wall motion technique. Healthy subjects had their arteries insonated at the same sitting by two different observers and at two different sittings by the same observer. From 32 subjects in the reproducibility study, within-scan coefficient of variation (CV) was 4.5%. Intraobserver between-scan CV for E was 12.7% and for Ep 11.0%. Interobserver CVs were 8.3% and 9.3%, respectively. TDI is a reproducible, valid and highly sensitive direct assessment of arterial wall parameters. It is at least as reproducible as other ultrasound based methods for assessing arterial stiffness and also provides increased information about the arterial distension waveform. (E-mail: martin@claridge.org.uk)