Eye Plot Research Articles

Simple graphical methods of displaying multiple clinical results

A common challenge in clinical research trials is for applied statistics to manage, analyse, summarize and report an enormous amount of data. Nowadays, due to advances in medical technology, situations frequently arise where it is difficult to display and interpret results. Consequently, a creative approach is required to summarize the main outcomes of the statistical analyses in a form which is easy to grasp, to interpret and possibly to remember. In this paper a number of clinical case studies are provided. Firstly, a topographical map of the brain summarizing P-values obtained from comparisons across different EEG sites; secondly, a bulls eye plot, showing the agreement between observers in different regions of the heart; thirdly, a pictorial table reporting inter- and intra-rater reliability scores of a speech assessment; fourthly a star-plot to deal with numerous questionnaire results and finally a correlogram to illustrate significant correlation values between two diagnostic tools. The intention of this paper is to encourage the effort of visual representations of multiple statistical outcomes. Such representations do not only embellish the report, but aid interpretation by conveying a specific statistical meaning.

Comparison of 180/spl deg/ and 360/spl deg/ iterative reconstruction with non-uniform attenuation compensation for Tl-201 SPECT

This study compares Tl-201 SPECT images reconstructed from 180/spl deg/ and 360/spl deg/ projection data, using iterative reconstruction with non-uniform attenuation compensation. Using a mathematical phantom of the human thorax, Monte Carlo simulation is used to produce both 180/spl deg/ (45/spl deg/ RAO to 45/spl deg/ LPO) and 360/spl deg/ Tl-201 SPECT projection data. Included in the simulation are the effects of non-uniform attenuation, detector response, scatter and statistical noise. The 180/spl deg/ and 360/spl deg/ data were taken over 64 and 128 angles, respectively, assuming the same total acquisition time for both. The simulated projection data were reconstructed with nonuniform attenuation compensation using the ML-EM algorithm for 50 iterations and, for comparison, were also reconstructed without attenuation compensation using the filtered backprojection method with a ramp filter. Transaxial slices of the reconstructed images, image profiles and Bull's-eye plots all show that images reconstructed with attenuation compensation, unlike those reconstructed without attenuation compensation, are essentially the same within the region of the myocardium for the 180/spl deg/ and 360/spl deg/ data, with few artifacts and similar image contrast. Furthermore, for the same total imaging time, the images reconstructed from the 180/spl deg/ data have slightly less noise in the myocardial region.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Evaluation of corrective reconstruction methods using a 3D cardiac-torso phantom and bull's-eye plots

The goal of the authors' investigation was to study the effectiveness of the corrective reconstruction methods in cardiac SPECT using a realistic phantom and to qualitatively and quantitatively evaluate the reconstructed images using bull's-eye plots. A 3D mathematical phantom which realistically models the anatomical structures of the cardiac-torso region of patients was used. The phantom allows simulation of both the attenuation distribution and the uptake of radiopharmaceuticals in different organs. Also, the phantom can be easily modified to simulate different genders and variations in patient anatomy. Two-dimensional projection data were generated from the phantom and included the effects of attenuation and detector response blurring. The reconstruction methods used in the study included the conventional filtered backprojection (FBP) with no attenuation compensation, and the first-order Chang algorithm, an iterative filtered backprojection algorithm (IFBP), the weighted least square conjugate gradient algorithm and the ML-EM algorithm with non-uniform attenuation compensation. The transaxial reconstructed images were rearranged into short-axis slices from which bull's-eye plots of the count density distribution in the myocardium were generated. The FBP reconstructed images clearly demonstrated the effects of attenuation on the myocardial distribution caused by anatomical structures and the inadequacy of the algorithm to provide accurate quantitative reconstructions. The images reconstructed using the Chang, IFBP, and ML-EM methods with attenuation compensation showed substantial improvement in terms of reduction in artifacts and improvement in quantitative accuracy. The results also demonstrate that the ML-EM method is the most robust in attenuation compensation for a wide range of anatomical variations when compared to the Chang and IFBP methods. The combination of the 3D mathematical phantoms and bull's-eye plots provides an effective tool for evaluation of corrective reconstruction methods for quantitative cardiac SPECT.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Three-dimensional echocardiography for quantitative left ventricular wall motion analysis: a method for reconstruction of endocardial surface and evaluation of regional dysfunction.

A method for quantitative LV wall motion analysis based on 3-D reconstruction of the LV endocardial surface is presented. The reconstruction is based on a minimum of three transthoracic apical 2-D cineloops of the LV, digitally transferred from the ultrasound scanner to a computer. Images are obtained by rotating the transducer around the LV long axis. Endocardial borders are traced with an automatic edge detection algorithm with manual correction. These borders are used with a specially designed computer algorithm for reconstruction of LV cavity 3-D shape, and LV volumes, ejection fraction, and endocardial surface area can be determined. The end-diastolic and end-systolic endocardial surfaces are compared for analysis of regional wall motion. A threshold value is selected to discriminate between normal and abnormal wall motion. Regional wall motion abnormalities are displayed in a bull's eye plot, and the corresponding endocardial surface area is expressed in percent of the total endocardial area. Phase analysis is performed from reconstruction of the endocardial surface throughout the cardiac cycle, and displays regions with abnormal wall motion as being out of phase with LV volume variation. Thus, LV 3-D reconstruction performed by this method can be used for quantitative analysis of wall motion in several clinical situations, and due to the simplicity of processing the data, can be useful outside the research laboratory.

Two dimensional polar display of cardiac blood pool SPECT.

A new method of ECG gated cardiac blood pool SPECT to illustrate the left ventricular (LV) wall motion in a single static image, two dimensional polar display (2DPD), was described. Circumferential profiles of the difference between end diastolic and end systolic short axis images of the LV were displayed in a similar way to the bull's eye plot of 201Tl myocardial SPECT. The diagnoses by 2DPDs agreed with those by cinematic displays of ECG gated blood pool SPECT in 74 out of 84 segments (85.5%) of abnormal motion, and 155 our of 168 segments (80.3%) of normal motion. It is concluded that 2DPD can evaluate regional wall motion by a single static image in a significant number of patients, and is also useful in comparing with the bull's eye image of 201Tl myocardial SPECT.