Eyeball Method Research Articles

Use of a Novel Deep Learning Open-Source Model for Quantification of Ki-67 in Breast Cancer Patients in Pakistan: A Comparative Study between the Manual and Automated Methods.

Introduction: Breast cancer is the most common cancer in women; its early detection plays a crucial role in improving patient outcomes. Ki-67 is a biomarker commonly used for evaluating the proliferation of cancer cells in breast cancer patients. The quantification of Ki-67 has traditionally been performed by pathologists through a manual examination of tissue samples, which can be time-consuming and subject to inter- and intra-observer variability. In this study, we used a novel deep learning model to quantify Ki-67 in breast cancer in digital images prepared by a microscope-attached camera. Objective: To compare the automated detection of Ki-67 with the manual eyeball/hotspot method. Place and duration of study: This descriptive, cross-sectional study was conducted at the Jinnah Sindh Medical University. Glass slides of diagnosed cases of breast cancer were obtained from the Aga Khan University Hospital after receiving ethical approval. The duration of the study was one month. Methodology: We prepared 140 digital images stained with the Ki-67 antibody using a microscope-attached camera at 10×. An expert pathologist (P1) evaluated the Ki-67 index of the hotspot fields using the eyeball method. The images were uploaded to the DeepLiif software to detect the exact percentage of Ki-67 positive cells. SPSS version 24 was used for data analysis. Diagnostic accuracy was also calculated by other pathologists (P2, P3) and by AI using a Ki-67 cut-off score of 20 and taking P1 as the gold standard. Results: The manual and automated scoring methods showed a strong positive correlation as the kappa coefficient was significant. The p value was <0.001. The highest diagnostic accuracy, i.e., 95%, taking P1 as gold standard, was found for AI, compared to pathologists P2 and P3. Conclusions: Use of quantification-based deep learning models can make the work of pathologists easier and more reproducible. Our study is one of the earliest studies in this field. More studies with larger sample sizes are needed in future to develop a cohort.

Structured Cardiac Assessment Outperforms Visual Estimation in Novice Ultrasound Users: A Randomized Controlled Trial

BackgroundTwo evidence-based techniques to determine left ventricular (LV) systolic function are taught in emergency medicine curricula. The first is a “structured approach,” which qualitatively evaluates LV fractional shortening, E-point septal separation, and LV diameter. The other is the “eyeball method,” which qualitatively estimates the LV ejection fraction (LVEF). ObjectiveThe aim of this study was to determine whether the structured approach or the eyeball method was superior for teaching LVEF estimation to novices. MethodsMedical students were recruited to participate in our randomized controlled trial. Participants were randomized to the structured approach group or eyeball method group and completed one of two 15-min educational modules. Participants subsequently interpreted 12 echocardiogram clips to determine LV function. The primary outcome was the percentage of correct interpretations as determined by a cardiologist. ResultsSeventy-four participants were invited to participate and 32 completed the study (15 in the structured approach and 17 in the eyeball method groups). The majority (30 of 32 [93.75%]) were first- and second-year medical students with no prior ultrasound training. The mean time to complete the training was similar between groups (16.8 vs. 17.8 min; p = 0.66). The primary outcome of percent of correct interpretations was significantly higher in the structured approach group compared with the eyeball method group (88.9% vs. 73.0%; p < 0.01). ConclusionsTraining novice ultrasound users in a structured qualitative LV assessment method was more effective than the eyeball method. Learners were able to achieve high accuracy after a brief training intervention. These results may help inform best practices for undergraduate ultrasound curriculum development.

Ki-67 Quantification in Breast Cancer by Digital Imaging AI Software and its Concordance with Manual Method.

To validate the concordance of automated detection of Ki67 in digital images of breast cancer with the manual eyeball / hotspot method. Descriptive study. Place and Duration of the Study: Jinnah Sindh Medical University, Karachi, from 1st January to 15th February 2022. Glass slides of cases diagnosed as invasive ductal carcinoma (IDC) were obtained from the Agha Khan Medical University Hospital, selected retrospectively and randomly from 60 patients. They were stained with the Ki67 antibody. An expert pathologist evaluated the Ki67 index in the hotspot fields using eyeball method. Digital images were taken from the hotspots using a camera attached to the microscope. The images were uploaded in the Mindpeak software to detect the exact percentage of Ki67-positive cells. The results obtained through automated detection were compared with the results reported by expert pathologists to see the differential outcome. The manual and automated scoring methods showed strong positive concordance (p <0.001). Automated scoring of Ki-67 staining has tremendous potential as the issues of lack of consistency, reproducibility, and accuracy can be eliminated. In the era of personalised medicine, pathologists can efficiently give a precise clinical diagnosis with the support of AI. Artificial intelligence, Algorithms, Breast cancer, Deep learning, Image detection, Ki-67.

Evaluation of septal perforation size using a novel measuring device.

Nasal septal perforations can be managed with a septal button prosthesis. While they do not restore the physiological function of the septal mucosa, they are able to improve laminar nasal airflow. With the development of septal buttons sized specifically to perforations, accurate measurement of perforations has become more important for patient satisfaction and comfort. This task can be difficult to accomplish in the clinical setting. In this study, 2 new instruments developed to measure septal perforations were evaluated for accuracy and ease of use. Two types of measuring devices ("sizers") were created via 3D printing. One type included six serial, progressively sized instruments (serial sizers) and the other included two instruments with several size gradations (graded sizers). Septal perforations of varying sizes were surgically created in five fresh-frozen cadaver heads. Using a headlight and nasal speculum, 15 otolaryngology trainees and consultants were asked to measure the perforations (length × height) via four different methods: "eyeball" estimation, a ruler, the serial sizers, and the graded sizers. They were also asked to evaluate the methods themselves. An accurate measurement was defined as ± 1mm of the true measurement. A combination of Chi-square analysis and ANOVA was used to assess the accuracy and ease of use of the four methods. Chi-square analysis showed that the sizers were more accurate than the two traditional methods (eyeball and ruler) for measuring perforation length (73% vs. 44%, p = 4.8 × 10-7) and height (71% vs. 50%, p = 0.0003). ANOVA showed that the eyeball method overestimated perforation length significantly more than the other three methods (p = 0.002), and was also significantly less accurate than the other three methods (p < 0.001). Chi-square analysis did not show any correlation between participant training experience and measurement accuracy for any of the three methods. Participant comments and scores demonstrated a clear preference for the two sizers over the traditional methods. The two novel sizers studied here were significantly more accurate and easier to use than traditional methods for measuring nasal septal perforations. With broader implementation and study of these devices, there is potential to improve patient care surrounding septal perforations.

Vitamin C and scar strength: analysis of a historical trial and implications for collagen-related pathologies

A double-blind controlled trial initiated in 1944 has led to the common narrative that a 10-mg daily vitamin C intake is adequate to prevent and treat impaired wound healing, and by inference, other collagen-related diseases such as heart disease or stroke. The WHO relies on this narrative to set the recommended nutrient intake for vitamin C. This narrative, however, is based on what is known as the eyeball method of data assessment. The 1944 trial published individual participant data on scar strength providing an opportunity to statistically probe the validity of the 10-mg narrative, something which has not yet been done. The findings show that a vitamin C intake that averages to 10mg/d over a mean follow-up of 11.5 mo was associated with a 42% weakened scar strength when compared with 80mg vitamin C intake/d (P<0.001). The observed dose-response curve between scar strength and vitamin C intake suggests that the daily vitamin C intake needed to prevent collagen-related pathologies is in the range recommended by the National Academy of Medicine and the European Food Safety Authority (75 to 110mg/d), not the WHO recommendation (45mg/d). The findings also show that a vitamin C intake that averages to 65mg/d over a mean follow-up of 6.5 mo failed to restore the normal wound-healing capacity of vitamin C-depleted tissues; such tissues had a 49% weaker scar strength when compared with nondepleted tissues (P<0.05). Thus, average daily vitamin C intakes ∼50% higher than the WHO recommends may fail to treat existing collagen-related pathologies. It is concluded that the prior lack of statistical analyses of a landmark trial may have led to a misleading narrative on the vitamin C needs for the prevention and treatment of collagen-related pathologies.

Sustainable development of territorial units: MCDM approach with optimal tail selection

In the face of accelerating climate change, economic instability and limited resources, it is essential to find indicators that better measure the sustainable development of territorial units. Despite ambiguous definitions of sustainable development, numerous studies describe quantitative indicators of sustainable development. Main methodological problems include data availability and their use, spatial and time scales, selection of indicators, and their aggregation. Usually, analysts and decision-makers apply well known conventional methods that have numerous limitations. These methods in many cases cause excessive simplification of the real phenomena and relations between their determinants. Moreover, variables describing the development of territorial units (especially the environmental pillar) are often characterized by strong asymmetry or extreme observations. Even a single outlier for a given territorial unit may significantly affect the analysis and the resulting conclusions.The objective of this paper is to present the application potential of a Multi-Criteria Decision Making (MCDM) approach with an optimal tail selection to assess the sustainable development of territorial units. The proposed approach is based on the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and different methods of optimal tail selection of variable distribution. The Oja's spatial median and the optimal tail selection methods are used to reduce the impact of strong asymmetry and extreme values of variables. Moreover, the measure of cluster compactness is proposed for the evaluation of the proposed method. The proposed approach was used to assess the sustainable development of municipalities in Poland in 2018. We found that the automated Eye-Ball method and the Guillou and Hall's method enabled correct identification of extreme values of variables describing the economic, social, and environmental development of municipalities. This made it possible to distinguish the types of sustainable development level and its pillars and enabled to provide the statuses of the sustainable development level of the examined municipalities with respect to other municipalities in Poland.

An Optimal Tail Selection in Risk Measurement

The appropriate choice of a threshold level, which separates the tails of the probability distribution of a random variable from its middle part, is considered to be a very complex and challenging task. This paper provides an empirical study on various methods of the optimal tail selection in risk measurement. The results indicate which method may be useful in practice for investors and financial and regulatory institutions. Some methods that perform well in simulation studies, based on theoretical distributions, may not perform well when real data are in use. We analyze twelve methods with different parameters for forty-eight world indices using returns from the period of 2000–Q1 2020 and four sub-periods. The research objective is to compare the methods and to identify those which can be recognized as useful in risk measurement. The results suggest that only four tail selection methods, i.e., the Path Stability algorithm, the minimization of the Asymptotic Mean Squared Error approach, the automated Eyeball method with carefully selected tuning parameters and the Hall single bootstrap procedure may be useful in practical applications.

Reliability testing of the heel marker in three-dimensional gait analysis

IntroductionIn three-dimensional gait analysis, anatomical axes are defined by and therefore sensitive to marker placement. Previous analysis of the Oxford Foot Model (OFM) has suggested that the axes of the hindfoot are most sensitive to marker placement on the posterior aspect of the heel. Since other multi-segment foot models also use a similar marker, it is important to find methods to place this as accurately as possible.The aim of this pilot study was to test two different ‘jigs’ (anatomical alignment devices) against eyeball marker placement to improve reliability of heel marker placement and calculation of hindfoot angles using the OFM. MethodsTwo jigs were designed using three-dimensional printing: a ratio caliper and heel mould. OFM kinematics were collected for ten healthy adults; intra-tester and inter-tester repeatability of hindfoot marker placement were assessed using both an experienced and inexperienced gait analyst for 5 clinically relevant variables. ResultsFor 3 out of 5 variables the intra-tester and inter-tester variability was below 2 degrees for all methods of marker placement. The ratio caliper had the lowest intra-tester variability for the experienced gait analyst in all 5 variables and for the inexperienced gait analyst in 4 out of 5 variables. However for inter-tester variability, the ratio caliper was only lower than the eyeball method in 2 out of the 5 variables. The mould produced the worst results for 3 of the 5 variables, and was particularly prone to variability when assessing average hindfoot rotation, making it the least reliable method overall. ConclusionsThe use of the ratio caliper may improve intra-tester variability, but does not seem superior to the eyeball method of marker placement for inter-tester variability. The use of a heel mould is discouraged.

Evolution of numerical model to identify the intersection of vibratory motion equations with discrete points in a mechanical system

Some mathematical functions which can’t be solved analytically and the solution for these functions can be determined by the intersection of their graphical plots. Computer programmes represent these functions with discrete points which are not continuous in nature. Since the resolution of the discretization is limited, the graphs may intersect in the interval between two points. It is difficult to find the intersection value of these functions from the computer plotted graphs as the intersection points do not exist. In such cases, intersection points can be approximately found by eye ball method, or by increasing the number of discrete points. This paper discusses about a logical method to find the intersection points of two discretely plotted graphs with much better accuracy. Novelty of this work is the improvement in the accuracy and resolution of determination of intersection points between two discretised graphs without increasing the resolution of discretisation. Existing methods requires increasing the number of discretised points to improve the accuracy and resolution in the determination of intersection points. A problem related to simulation of vibratory induced motions is taken as an example.

Value at Risk Estimation Using the GARCH-EVT Approach with Optimal Tail Selection

A conditional Extreme Value Theory (GARCH-EVT) approach is a two-stage hybrid method that combines a Generalized Autoregressive Conditional Heteroskedasticity (GARCH) filter with the Extreme Value Theory (EVT). The approach requires pre-specification of a threshold separating distribution tails from its middle part. The appropriate choice of a threshold level is a demanding task. In this paper we use four different optimal tail selection algorithms, i.e., the path stability method, the automated Eye-Ball method, the minimization of asymptotic mean squared error method and the distance metric method with a mean absolute penalty function, to estimate out-of-sample Value at Risk (VaR) forecasts and compare them to the fixed threshold approach. Unlike other studies, we update the optimal fraction of the tail for each rolling window of the returns. The research objective is to verify to what extent optimization procedures can improve VaR estimates compared to the fixed threshold approach. Results are presented for a long and a short position applying 10 world stock indices in the period from 2000 to June 2019. Although each approach generates different threshold levels, the GARCH-EVT model produces similar Value at Risk estimates. Therefore, no improvement of VaR accuracy may be observed relative to the conservative approach taking the 95th quantile of returns as a threshold.

Bedaquiline and linezolid MIC distributions and epidemiological cut-off values for Mycobacterium tuberculosis in the Latin American region.

To describe the distributions of bedaquiline and linezolid MIC values for the Mycobacterium tuberculosis WT population and to define the corresponding epidemiological cut-offs (ECOFFs) in three Latin American countries. MICs of bedaquiline and linezolid were determined by the resazurin microtitre assay (REMA). In phase 1, interlaboratory reproducibility was assessed using a panel of 10 fully susceptible M. tuberculosis strains. Phase 2 involved MIC determination for 248 clinical isolates from Argentina (n = 58), Brazil (n = 100) and Peru (n = 90) from patients who were treatment-naive for bedaquiline and linezolid. We then determined the ECOFFs for bedaquiline and linezolid by the eyeball method and the ECOFFinder statistical calculator. Phase 1: REMA MIC values in the three sites were either identical to each other or differed by one 2-fold dilution from the consensus value with the exception of a single value. Phase 2: the bedaquiline MIC range was 0.0039-0.25 mg/L for pan-susceptible and drug-resistant isolates combined. The linezolid MIC range was 0.062-0.5 mg/L for pan-susceptible isolates and 0.031-4 mg/L for drug-resistant isolates. ECOFFs were 0.125 mg/L for bedaquiline and 0.50 mg/L for linezolid. REMA is reproducible and robust for the determination of bedaquiline and linezolid MIC distributions and ECOFF values when applied in laboratories of medium/low-resource countries. We suggest that WT MIC distributions for both drugs should be used as a monitoring tool to control the possible rapid emergence of resistance.

Performance Comparison of Algorithms for Real-Time Rate-of-Penetration Optimization in Drilling Using Data-Driven Models

Summary Real-time drilling optimization is a topic of significant interest because of its economic value, and its importance increases particularly during periods of low oil prices. This paper evaluates different optimization strategies and algorithms for real-time optimization of an objective function (function to be optimized) specific to drilling. The objective function optimized here is derived from a data-driven (or machine-learning) model with an unknown functional form. A data-driven model has been used to calculate the objective function [rate of penetration (ROP)] because it has been shown to be more efficient in ROP prediction relative to deterministic models (Hegde and Gray 2017). The data-driven ROP model is built using machine-learning algorithms; measured drilling parameters [weight on bit (WOB), revolutions per minute (rev/min), strength of rock, and flow rate] are used as inputs to predict the ROP. Real-time drilling optimization that is data-driven is challenging because of run-time constraints. This is perceived as a handicap for data-driven models because their functional form is unknown, making them more difficult to optimize. This paper evaluates algorithms depending on their ability to best maximize the objective (ROP) and their time effectiveness. Two simple yet robust algorithms, the eyeball method and the random-search method, are presented as plausible solutions to this problem. These methods are then compared with popular metaheuristic algorithms, evaluating the tradeoff between improvement in the objective (search for a global optimal) and the computational time of run. Using results from the simulations conducted in this paper, we concluded that data-driven models can be used for real-time drilling despite their computational constraints by choosing the right optimization algorithm. The best tradeoff in terms of ROP increase as well as computational efficiency evaluated in this paper is the simplex algorithm. The ROP was improved by 30% on average with a variance of 2.5% in the test set over 14 formations that were tested.

Approach to undifferentiated dyspnea in emergency department: aids in rapid clinical decision-making

BackgroundDiagnosis and management of patients presenting with acute dyspnea is one of the major challenges for physicians in emergency department (ED). A correct diagnosis is frequently delayed and difficult to ascertain, and clinical uncertainty is common, explaining the need for rapid diagnosis and a management plan. The primary aim of our study is to assess a diagnostic strategy using multiorgan point of care ultrasonography (USG) to differentiate patients presenting with acute dyspnea to ED into different diagnostic categories for timely management in a resource-limited setting.MethodsThis is a prospective cohort study which assessed the diagnostic performance of a strategy in evaluating patients presenting with undifferentiated dyspnea as primary predominant complaint to ED. Focused multiorgan USG which includes cardiac USG for left ventricle systolic function, right ventricle enlargement, and pericardial effusion, inferior vena cava (IVC) diameter and collapsibility, lung USG to identify various patterns (acute interstitial syndrome, pneumothorax, pleural effusion, consolidation, etc.) and renal USG to assess kidney size and echotexture was performed. Later, patients were grouped into one of ten clinical syndromes defined in the study based on USG and clinical patterns. Emergency diagnosis was compared with final hospital diagnosis to assess the accuracy of this strategy.ResultsConcordance between ED diagnosis of dyspnea using the diagnostic strategy proposed in the study with final hospital diagnosis was high with agreement in 88% of patients (Kappa statistic = .805, p = .000) which is statistically significant. The most common diagnosis was acute decompensated heart failure (ADHF). Sensitivity and specificity of the diagnostic strategy used in this study to identify ADHF was 97.3 and 93.3%, respectively. On multivariate analysis, jugular venous distension, fever and cough, ejection fraction (by eyeball method), dilated IVC, absent to decreased lung sliding showed independent association in predicting cardiac and non-cardiac diagnosis.ConclusionsThe present study concludes that integrating focused multiorgan USG by lung-cardiac-IVC and renal ultrasound into routine clinical evaluation of patients with dyspnea has a higher accuracy for differentiating causes of dyspnea in emergency department. This strategy can be adopted even in resource limited setting.

Usefulness of mitral annular plane systolic excursion in assessment of left ventricular systolic function in mechanically ventilated obese patients

BackgroundThe management of mechanically ventilated patients depends on a combination of clinical skills and measurement of physiological parameters. ObjectivesWe evaluated the role of mitral annular plane systolic excursion (MAPSE) in the determination of left ventricular systolic function (LVSF) in mechanically ventilated obese patients. MethodsA convenient sample of 60 of 68 obese, mechanically ventilated patients in the intensive care unit were included in the study. Transthoracic echocardiogram MAPSE measurement (averaged from 3 consecutive cycles) on 2 separate days, vs the eyeball ejection fraction (classic clinical method) on 2 separate days, and vs the biplane Simpson (classic research and consultative echocardiogram method) on 2 separate days was obtained. In patients with non sinus rhythm, measurements were collected over 5 to 10 heartbeats. ResultsThere was a significant positive correlation between MAPSE and LVSF assessment using the eyeball method and Simpson method (r= 0.89 and 0.87, respectively; P< .001). Mitral annular plane systolic excursion was significantly shorter in duration (P< .001). ConclusionsMitral annular plane systolic excursion is useful, an easier technique, and shorter in duration compared with the eyeball method in the determination of LVSF in mechanically ventilated obese patients.

Some possibilities of spatial analysis of crimes in police work

Crime does not occur randomly. It tends to concentrate at particular places for reasons that can be explained in relation to victim and offender interaction and the opportunities that exist to commit crime. If the police knew where crime is concentrated (where are the hotspots) resources could be directed in order to take proactive actions. In order to identify hotspots, spatial distributions of crimes should be examined. Patterns in data must be identified, and underlying (spatial) processes must be understood in order to be effective in crime prevention. This could be achieved using spatial analysis techniques. In cases where spatial distribution is not complex and visually overwhelming the simple 'eyeball method' should be sufficient. But in cases where spatial distribution of a large number of crimes (events) is present, the spatial statistics is needed. Spatial statistics help cut through some of the subjectivity to get more directly at spatial patterns, trends, processes, and relationships. Today, the most commercial GIS solutions already have more or less developed statistical capabilities. In cases where built-in GIS statistical capabilities are not sufficient to satisfy particular research need, they must be supplemented by specialized statistical software. An example of the usage of spatial statistics is shown on the practical example using commercial robberies dataset in one of Belgrade's municipalities. The crime distribution is assessed using centro graphic measures (mean center, center of minimum distance, standard deviation ellipse). Centro graphic measures allows us to visualize a complex spatial trend, how quickly the mean center moves, and where it moves, is there changes in dispersion and/or orientation of the crime distribution etc., providing valuable information about the spatial processes promoting this crime shifts. The level of clustering was assessed calculating nearest neighbor index and finally clusters (i.e. hotspots) were identified using kernel density tool. Kernel density maps provide a realistic and accurate image of the location and shape of the hot spot distribution. In order to achieve complete understanding of the dynamics of crime activity at the hot spots, the analysis of spatial distribution isn't enough. Spatial analysis should be accompanied with analysis of time distribution of crimes at hot spots. This paper concludes that spatial analysis and spatial statistics techniques must be used in everyday crime mapping efforts aimed to provide analytical support to police decision making from tactical to strategic level.

Image Quality Influences the Assessment of Left Ventricular Function

Transesophageal echocardiography has become a standard tool for evaluating left ventricular function during cardiac surgery. However, the image quality varies widely between patients and examinations. The aim of this study was to investigate the influence of the image quality on 5 commonly used 2-dimensional methods. Transesophageal real-time 3-dimensional echocardiography (3DE) served as a reference. Left ventricular function was evaluated in 63 patients with sufficient real-time 3DE image quality. The image quality was rated using the ratio of the visualized border divided by the total endocardial border. These ratings were used to generate groups of poor (0%-40%), fair (41%-70%), and good (71%-100%) image quality. The ejection fraction (EF), end-diastolic volume, and end-systolic volume were analyzed by the Simpson method of disks (biplane and monoplane), eyeball method, Teichholz method, and speckle-tracking method. Furthermore, the fractional area change was determined. Each correlation with real-time 3DE was evaluated. Correlations of the EF and volumes, respectively, as determined by long-axis view methods increased with improving image quality: the Simpson biplane method was found to be the most accurate method, with good image quality for the EF (r = 0.946) and volumes (end-diastolic volume, r = 0.962; end-systolic volume, r = 0.989). Correlations of the EF and fractional area change by short-axis view methods decreased with improving image quality, with the Teichholz EF found to be most accurate with poor (r = 0.928) in contrast to good (r = 0.699) image quality. With good image quality, the Simpson biplane method is the most accurate 2-dimensional method for assessing the left ventricular EF. Short-axis view methods, especially the Teichholz method yield better correlations with poor image quality. The eyeball method was unaffected by image quality.

Is MRI the Preferred Method for Evaluating Right Ventricular Size and Function in Patients With Congenital Heart Disease?

Is MRI the Preferred Method for Evaluating Right Ventricular Size and Function in Patients With Congenital Heart Disease?

Assessment of Left Ventricular Size and Function during Cardiac Surgery. An Intraoperative Evaluation of Six Two‐Dimensional Echocardiographic Methods with Real Time Three‐Dimensional Echocardiography as a Reference

Transesophageal echocardiography is recommended to monitor left ventricular (LV) size and function in various operations. Generally, two-dimensional (2D) methods are applied intraoperatively. The aim of this study was to compare the accuracy and feasibility of 6 commonly used 2D methods to assess LV function during surgery. LV function in 120 consecutive patients was evaluated. Real time three-dimensional transesophageal echocardiograpy (3DTEE) served as reference. End-diastolic and end-systolic volumes and ejection fraction (EF) were analyzed with Simpson's method of discs (monoplane [MP] and biplane [BP]), eyeball method, Teichholz' method, and speckle tracking (ST) methods. Furthermore, fractional area change (FAC) and peak systolic pressure rise (dP/dt) were determined. Each 2D method was evaluated regarding correlation and agreement with 3DE, intra- and interobserver variability and the time required for evaluation. Simpson BP showed the strongest correlation and best agreement with 3DE for EF (limits of agreement 3.7±11.6%) and volumes. Simpson MP showed similar agreement with 3DE compared to ST (2.8±14.5% vs. 2.0±15.3% and 3.8±14.4% vs. 1.9±15.6%, respectively). Both the eyeball method and Teichholz' method showed wide limits of agreement (-1.5±18.2% and 5.2±22.1%, respectively). DP/dt did not correlate with 3DE. FAC and ST FAC showed similar agreement. Application of 3DE (429±108seconds) took the longest time, and the eyeball method took the shortest time (8±5seconds) for analysis. Simpson BP is the most accurate intraoperative 2D method to evaluate LV function, followed by long-axis MP evaluations. Short-axis views were less accurate but may be suited for monitoring. We do not recommend using dP/dt.

Checking adequacy of the semiparametric location shift model with censored data

The location shift model is commonly used to quantify the difference between groups in a two-arm study. Nonparametric inference procedures for the location shift parameter with censored observations have recently been extensively studied. However, the validity of these procedures depends heavily on the model assumption. In this article, a class of graphical and numerical methods are proposed for checking the adequacy of the location shift model. Our graphical procedures are much less subjective than the eye-ball method based on the standard Q-Q plot. The proposed methods are illustrated with real-life examples.

Corrections to the parabolic approximation in propagation modeling

An exact integral relation between the solutions of the Helmholtz and parabolic equations and its stationary phase evaluation has been previously reported [J. A. DeSanto, J. Acoust. Soc. Am. 60, S33 (A) (1976)]. The procedure yields corrections to the parabolic solution (P) which (among others) involve the second range derivative of P. We have programmed this latter correction using the (range-independent) AESD profiles and make a quantitative comparison (rms error as a function of range) between the exact normal mode (NM) result and P, on the one hand, and between NM and the corrected parabolic (CP) on the other. The improvement is dramatic. The rms errors (both including and excluding phase) of the NMCP comparison are at least a factor of 3 less than the NM-P errors. We illustrate the conclusions with extensive numerical results. To summarize: (a) the correction is functionally simple, (b) it's easy to program, and (e) it yields significantly improved results. Finally we remark that the quantitative comparison between propgation models is far better than the canonical eyeball method.