Scatter Graph Research Articles

Methods of verifying the output of the treatment planning system used for high dose rate (HDR) prostate brachytherapy

ObjectivesTo investigate the relationships between the planning target volume (PTV) and the total reference air kerma (TRAK) required to irradiate the prostate using the Nucletron microSelection 192Ir radioactive stepping source afterloader for the treatment of prostate cancer. MethodsUsing 54 patient plans, the relationship between the treatment planning system (TPS) TRAK (TRAKTPS) and the estimate and planimetry prostate volumes was investigated. Linear regression analysis was used to predict the TRAK (TRAKpred) using the prostate gland height, width and length (HWL) measurements. The TRAK was corrected using a conformal index (COIN) of the plan to improve the accuracy of the model. A further 54 patient plans were then used to evaluate the outcome of the linear regression lines. ResultsA formula was proposed (HxWxLxπ/5.19) to estimate the prostate volume, which showed a mean deviation from the planimetry volume of 0.0139±3.339cm3, where 69% was within ±10% of planimetry, and 96% within ±20%. Scatter graphs of TRAKTPS for 54 plans, showed a positive linear correlation, r=0.98, using the planimetry volume, and r=0.95 for the estimated volume. The further 54 treatment plans used for evaluation showed the TRAKpred was accurately predicted to ±10% for 100% of plans using the planimetry volume and 81% using the prostate volume estimate. ConclusionsThe verification method proposed was found to be accurate and independent of TPS parameters, with suitable acceptance margins of ±10%.

Systematic Review and Empirical Comparison of Contemporaneous EQ-5D and SF-6D Group Mean Scores

Group mean estimates and their underlying distributions are the focus of assessment for cost and outcome variables in economic evaluation. Research focusing on the comparability of alternative preference-based measures of health-related quality of life has typically focused on analysis of individual-level data within specific clinical specialties or community-based samples. To explore the relationship between group mean scores for the EQ-5D and SF-6D across the utility scoring range. Studies were identified via a systematic search of 13 online electronic databases, a review of reference lists of included papers, and hand searches of key journals. Studies were included if they reported contemporaneous mean EQ-5D and SF-6D health state scores. All (sub)group comparisons of group mean EQ-5D and SF-6D scores identifiable from text, tables, or figures were extracted from identified studies. A total of 921 group mean comparisons were extracted from 56 studies. The nature of the relationship between the paired scores was examined using ranked scatter graphs and analysis of agreement. Systematic differences in group mean estimates were observed at both ends of the utility scale. At the lower (upper) end of the scale, the SF-6D (EQ-5D) provides higher mean utility estimates. These findings show that group mean EQ-5D and SF-6D scores are not directly comparable. This raises serious concerns about the cross-study comparability of economic evaluations that differ in the choice of preference-based measures, although the review focuses on 2 of the available instruments only. Further work is needed to address the practical implications of noninterchangeable utility estimates for cost-per-QALY estimates and decision making.

Eye tracking for visualization evaluation: Reading values on linear versus radial graphs

An eye tracking methodology can help uncover subtle cognitive processing stages that are otherwise difficult to observe in visualization evaluation studies. Pros and cons of eye tracking methods are discussed here, including common analysis metrics. One example metric is the initial time at which all elements of a visualization that are required to complete a task have been viewed. An illustrative eye tracking study was conducted to compare how radial and linear graphs support value lookup tasks for both one and two data-dimensions. Linear and radial versions of bar, line, area, and scatter graphs were presented to 32 participants, who each completed a counterbalanced series of tasks. Tasks were completed more quickly on linear graphs than on those with a radial layout. Scanpath analysis revealed that a three-stage processing model was supported: (1) find desired data dimension, (2) find its datapoint, and (3) map the datapoint to its value. Mapping a datapoint to its value was slower on radial than linear graphs, probably because eyes need to follow a circular, as opposed to a linear path. Finding a datapoint within a dimension was harder using line and area graphs than bar and scatter graphs, possibly due to visual confusion of the line representing a data series. Although few errors were made, eye tracking was also used here to classify error strategies. As a result of these analyses, guidelines are proposed for the design of radial and linear graphs.

Statistical Analysis on Software Metrics Affecting Modularity in Open Source Software

Modularity has been identified by many researchers as one of the success factors of Open Source Software (OSS) Projects. This modularity trait are influenced by some aspects of software metrics such as size, complexity, cohesion, and coupling. In this research, we analyze the software metrics such as Size Metrics (NCLOC, Lines, and Statements), Complexity Metrics (McCabe's Cyclomatic Complexity), Cohesion Metrics (LCOM4), and Coupling Metrics (RFC, Afferent coupling and Efferent coupling) of 59 Java-based OSS Projects from Sourceforge.net. By assuming that the number of downloads can be used as the indication of success of these projects, the OSS Projects being selected are the projects which have been downloaded more than 100,000 times. The software metrics reflecting the modularity of these projects are collected using SONAR tool and then statistically analyzed using scatter graph, Pearson r product-moment correlation, and least-square-fit linear approximation. It can be shown that there are only three independent metrics reflecting modularity which are NCLOC, LCOM4, and Afferent Coupling, whereas there is also one inconclusive result regarding Efferent Coupling

Assessment of Iranian chickpea (Cicer arietinum L.) germplasms for drought tolerance

Abstract Iran is one the most important centers of diversity for chickpea in south western Asia. Landraces are well adapted to local environmental conditions, and have evolved a range of morphological, phenological and physiological mechanisms to efficiently utilize the available water in a dry environment. In order to study some of these mechanisms, 150 genotypes of chickpea (Kabuli type) were evaluated using Augmented Designs for Preliminary Yield Trials under stress (Rainfed) and nonstress (Irrigated) conditions in Research Field of Mashhad College of Agriculture, Ferdowsi University of Mashhad, during 2005–2006 growing season. Then, based on the obtained results, four candidate genotypes for drought tolerance and two susceptible ones were evaluated in a pot experiment at open door situation in stressed (25% Field Capacity) and non-stressed (Field Capacity) conditions based on a factorial trial in Randomized Complete Block Design. There were positive and highly significant correlations between quantitative drought resistance indices such as MP, GMP, STI and HM with yield in stress and nonstress conditions. Also, there were positive and high significant correlations for SSI and DRI with yield in nonstress and stress conditions, respectively. Based on drought resistance indices and DRI, MCC544, MCC696 and MCC693 genotypes were superior to others, so they can be viewed as promising genotypes for drought resistance. These results were approved using three dimensional scatter graph and multivariate biplot graph. In stress condition, there were negative and high significant correlations between yield and days to flowering. Drought stress decreased leaf area per plant in all genotypes, significantly. In stressed and non-stressed conditions, leaf area in susceptible genotypes was more than that in tolerant genotypes, thus drought tolerance may be attributed to less transpiration and water loss because of smaller leaf size and reduced leaf area expansion in tolerant genotypes when drought stress develops.

Comparative application of two methods (COP and PaPRIKa) for groundwater vulnerability mapping in Mediterranean karst aquifers (France and Spain)

A comparative test of two vulnerability mapping methods (COP and PaPRIKa) specifically dedicated to for karst aquifers was carried out on two Mediterranean carbonate aquifers. The vulnerability maps obtained for each aquifer present important differences. To identify and determine the origin of these differences, the results were statistically analyzed using sensitivity analysis, coefficients of determination and scatter graphs. In addition, the global vulnerability (Gv) parameter was used to measure the general vulnerability of the aquifer and to compare the results obtained. This statistical analysis led us to conclude that the main cause of differences between these two methods used to assess aquifer vulnerability lie in the relative importance of the parameters employed in calculating the vulnerability index. For the PaPRIKa method, the variable related to infiltration (slope and karst features) has the most influence, with less weight being assigned to the protective capacity of layers overlying the aquifer. For the COP method, the most influent variable is defined by the layers overlying the aquifer, together with infiltration characteristics, determined by the relative importance of different forms of infiltration in each aquifer. The vulnerability mappings performed using the COP method present greater coherence with the known hydrogeological behavior of the study areas, especially the Spanish aquifers. Nevertheless, further hydrogeological investigations are needed, such as ones to validate the obtained vulnerability maps.

Classification of scattering media within benign and malignant breast tumors based on ultrasound texture‐feature‐based and Nakagami‐parameter images

Benign and malignant tumors can be classified by using texture analysis of the ultrasound B-scan image to describe the variation in the echogenicity of scatterers. The recently proposed ultrasonic Nakagami parametric image has also been used to detect the concentrations and arrangements of scatterers for tumor characterization applications. B-scan-based texture analysis and the Nakagami parametric image are functionally complementary in ultrasonic tissue characterizations and this study aimed to combine these methods in order to improve the ability to characterize breast tumors. To validate this concept, radio-frequency data obtained from 130 clinical cases were used to construct the texture-feature parametric image and the Nakagami parametric image. Four texture-feature parameters based on a gray-level co-occurrence matrix (homogeneity, contrast, energy, and variance) and the Nakagami parameters of the benign and malignant tumors were calculated. The usefulness of an individual parameter was determined and scatter graphs indicated the relationship between two selected texture-feature parameters. Fisher's linear discriminant analysis was used to combine the selected texture-feature parameters with the Nakagami parameter. The performance in classifying tumors was evaluated based on the receiver operating characteristic curve. The results indicated that there is a trade-off between sensitivity and specificity when using an individual texture-feature parameter or when combining two such correlated parameters to discriminate benign and malignant cases. However, the best performance was obtained when combining selected texture-feature parameters with the Nakagami parameter. The study findings suggest that combining B-scan-based texture analysis and the Nakagami parametric image could improve the ability to classify benign and malignant breast tumors.

Assessment of cerebral circulation in normal fetuses by three-dimensional power Doppler ultrasonography

To assess the three-dimensional power Doppler ultrasonography (3D power Doppler) vascular indices in the middle cerebral artery (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA) territories. A cross-sectional study was carried out on 111 normal pregnancies between 26 and 34 weeks. The MCA, ACA and PCA territories closest to the transducer were scanned and volumes were calculated by using the VOCAL (Virtual Organ Computer-aided Analysis) program. The 3D power Doppler indices--vascularization index (VI), flow index (FI) and vascularization-flow index (VFI) were calculated. Scatter graphs, Pearson correlation coefficients (r) and linear regression models were used. Only the FI-MCA (r=0.38 and p<0.001), VFI-MCA (r=0.23 and p=0.016) and FI-PCA (r=0.191 and p=0.040) had a low correlation with gestational age. The other 3D power Doppler indices VI-MCA (r=0.153 and p=0.150), VI-ACA (r=0.105 and p=0.271), FI-ACA (r=0.154 and p=0.106), VFI-ACA (r=0.134 and p=0.161), VI-PCA (r=0.105 and p=0.270) and VFI-PCA (r=0.126 and p=0.180) showed no statistically significant correlation with gestational. It was observed a low correlation between gestational age and the FI-MCA, VFI-MCA and FI-PCA.

Application of Wavelet Analysis in EMG Feature Extraction for Pattern Classification

Nowadays, analysis of electromyography (EMG) signal using wavelet transform is one of the most powerful signal processing tools. It is widely used in the EMG recognition system. In this study, we have investigated usefulness of extraction of the EMG features from multiple-level wavelet decomposition of the EMG signal. Different levels of various mother wavelets were used to obtain the useful resolution components from the EMG signal. Optimal EMG resolution component (sub-signal) was selected and then the reconstruction of the useful information signal was done. Noise and unwanted EMG parts were eliminated throughout this process. The estimated EMG signal that is an effective EMG part was extracted with the popular features, i.e. mean absolute value and root mean square, in order to improve quality of class separability. Two criteria used in the evaluation are the ratio of a Euclidean distance to a standard deviation and the scatter graph. The results show that only the EMG features extracted from reconstructed EMG signals of the first-level and the second-level detail coefficients yield the improvement of class separability in feature space. It will ensure that the result of pattern classification accuracy will be as high as possible. Optimal wavelet decomposition is obtained using the seventh order of Daubechies wavelet and the forth-level wavelet decomposition.

Avaliação do comprimento e área do corpo caloso fetal por meio da ultrassonografia tridimensional

to establish reference values for the length and area of the fetal corpus callosum between the 20th and 33rd weeks of gestation using three-dimensional ultrasound (3DUS). this cross-sectional study involved 70 normal pregnancies with gestational age between 20 and 33 weeks. An Accuvix XQ instrument with a convex volumetric transducer (3 to 5 MHz) was used. To assess the corpus callosum, a transfrontal plane was obtained using the metopic suture as an acoustic window. Length was obtained by measuring the distance between the proximal and distal extremities of the corpus callosum. Area was obtained by manual tracing of the external corpus callosum surface. The means, medians, standard deviations, and maximum and minimum values were calculated for the corpus callosum length and area. Scatter graphs were created to analyze the correlation between corpus callosum length and area and gestational age and biparietal diameter, the quality adjustments was verified according to the determination coefficient (R²). The intraclass correlation coefficient (ICC) was used to assess the intraobserver variability. mean corpus callosum length increased from 21.7 (18.6 - 25.2 mm) to 38.7 mm (32.6 - 43.3 mm) between 20 and 33 weeks of pregnancy, respectively. Mean corpus callosum area increased from 55.2 (41.0 - 80.0 mm²) to 142.2 mm² (114.0 - 160.0 mm²), between 20 to 33 weeks of pregnancy, respectively. There was a strong correlation between corpus callosum length and area and gestational age (R² = 0.7 and 0.7, respectively) and biparietal diameter (R² = 0.7 and 0.6, respectively). Intraobserver variability was appropriate, with an ICC of 0.9 and 0.9 for length and area, respectively. reference values for corpus callosum length and area were established for fetuses between 20 and 33 weeks gestation. Intraobserver variability was appropriate.

Predicting the Ideal Serum Creatinine of Kidney Transplant Recipients by a Simple Formula Based on the Balance Between Metabolic Demands of Recipients and Renal Mass Supply From Donors

Serum creatinine (Scr) is the most frequently used test to estimate graft function after kidney transplantation. Our previous study demonstrated that the independent predictors of recipient posttransplantation Scr included the ratio of graft weight to recipient body weight, the ratio of graft weight to recipient body surface area (BSA), and the ratio of graft weight to recipient body mass index (BMI). A prospective analysis about the impact of the balance between metabolic demands and renal supply on posttransplantation Scr of recipients was previously reported. We plotted the scatter graph using the X-axis as the independent predictors of Scr by linear regression and the Y-axis as the recipient Scr. To generate the predictive formula of Scr, we calculated a fit of the line of plotted cases using a linear regression method with 2 regression lines for prediction of the upper and lower 95% confidence intervals. Each line was converted into a predictive formula: Scr = −0.0033* (Graft weight(g)/Recipient BSA(m 2))+1.75. Under 95% confidence, the Scr ranges from −0.0033* (Graft weight(g)/Recipient BSA(m 2))+1.07 to −0.0033* (Graft weight(g)/Recipient BSA (m 2))+2.44. Scr = −0.1049* (Graft weight(g)/Recipient body weight(kg))+1.72, which ranges from −0.1049* (Graft weight(g)/Recipient body weight(kg))+1.06 to −0.1049* (Graft weight(g)/Recipient body weight(kg))+2.37. Scr = −0.0158* (Graft weight(g)/Recipient BMI(kg/m 2))+1.56, which ranges from −0.0158* (Graft weight(g)/Recipient BMI(kg/m 2))+0.75 to −0.0158* (Graft weight(g)/Recipient BMI(kg/m 2))+2.26. Prediction of posttransplantation Scr may be achieved by measuring graft weight as well as recipient weight and height. When recipient Scr is significantly higher than that predicted by the formula, a clinician should suspect an underlying graft injury.

Quantitative Analysis of Echocardiographic Cine-Loops Using a 2D-Strain Algorithm in Correlation with Thallium-201 SPECT Imaging

The aim of this study was to investigate the correlation between the regional left ventricular (LV) contractility, assessed by two-dimensional (2D)-strain echocardiographic images, and regional LV perfusion, determined by thallium-201 single photon emission computed tomography (SPECT) imaging. Forty-five hospitalized patients with suspected myocardial ischemia (32 males, mean age 69 ± 12 years) have undergone both echocardiography and SPECT imaging on the same day. The echocardiographic data has been obtained in three apical views. The data for each view has been processed by the 2D-strain algorithm, to produce six peak systolic longitudinal strain measurements per view, one per segment. The resulting measurements have been compared with the corresponding regions within the SPECT bull's-eye map (at rest). In order to handle inaccuracies in the positioning of the echocardiographic transducer, the two datasets have undergone registration based on local correlation. The mean correlation coefficients between SPECT perfusion and peak systolic longitudinal strain for the apical long-axis, apical two-chamber, and apical four-chamber views were 0.55 ± 0.36, 0.47 ± 0.35, and 0.64 ± 0.30 respectively (negative correlation coefficients have been considered as zero). The overall mean correlation coefficient was 0.56 ± 0.34. The scatter graphs of the average values of perfusion and the strain values showed a nonlinear relation between the two parameters. The average correlation coefficient is comparable to the values reported for the correlation between the average LV function, based on visual analysis of echocardiographic imaging, and the average LV perfusion, based on SPECT imaging. (E-mail: aaronisme@yahoo.com)

Physical properties of cement composites designed for aerostatic bearings

This paper investigates the physical properties of cement composites based on ordinary Portland cement (OPC) and silica particles as a potential material for porous aerostatic bearings for precision engineering applications. A full factorial design (2241) was carried out to study the effects of silica properties (size and geometry) and uniaxial pressure (10 and 30 MPa) on the composite properties, namely bulk density, apparent porosity and intrinsic permeability of the ceramic composites. Scatter graphs were plotted to identify the existence of significant correlations between parameters. The cementitious composite manufactured with small silica particles, non-spherical shape and low level of compaction pressure exhibited the most appropriate properties for the proposed application. In addition, mathematical models obtained from the response-correlation plots are potentially important tools for the development and design of new composites for porous bearing applications.

Quantitative backscattered electron imaging of bone in proximal femur fragility fracture and medical illness

Bone quality consists of a number of factors including the amount of bone, bone architecture and the degree of bone mineralization. Quantitative backscattered electron imaging is a technique that allows the degree of mineralization of trabeculae to be assessed and in this study is applied to inter-trochanteric bone biopsies of the proximal femur. Biopsy cores from 22 controls, nine individuals with acute and chronic medical conditions and 22 fragility fracture individuals undergoing total hip replacement were processed into methyl methacrylate, polished and analysed in a Philips XL20 scanning electron microscope. A mean and distribution of weight percent calcium were determined for each individual, and for the control, medically ill and fragility fracture groups. All individuals and groups of individuals showed normal distributions of percent calcium with both the ill and fragility fracture groups being under mineralized relative to the control group. The shape and position of the mineralization distributions suggest that the fragility group resulted from increased bone turnover with a slow progression to under mineralization. In contrast, the ill group appears to have had a more rapid change in the mineralization dynamic. Clear distinctions between the control, fragility fracture and medically ill groups could be seen when the mineralization data were plotted as a scatter graph against age. Graphing the data in this way showed an age-related increase in the degree of mineralization in control individuals with the under-mineralized, fragility fracture group scattered below this normal trend. The medically ill group was similarly less mineralized which highlighted the degree to which medical conditions and treatments can alter bone matrix mineralization.

Using C′ deviation to study structures of central amino acids in peptide fragments

In this investigation, we attempted to study the backbone geometry of amino acids in peptides using C' deviation. Diameters of distribution were used to describe the various atomic structures, and scatter graphs provided visual evaluation. The length of peptide fragments and the secondary structure of amino acids in the central position of the peptide fragments were also analyzed. The results showed that the atomic distribution of the central amino acids of five-residue peptide fragments was much more restricted than that of their corresponding three-residue peptide fragments. In identical three-residue fragments, atoms of central amino acids with different secondary structures, were distributed in distinct areas.

Study on the development of fetal cerebellum with virtual organ computer-aided analysis of three-dimensional ultrasonography

目的 应用三维超声技术监测胎儿小脑发育;探讨三维超声测量小脑体积的可行性,从而获取正常数据.方法 研究对象为571例正常胎儿,胎龄15～35周.随机选取30例行三维测量的组内及组间重复性检验.应用三维超声在体器官计算机辅助分析技术测量小脑体积,分析其与孕周、双顶径的关系.结果 三维超声测量小脑体积的重复性检验各组间差异无统计学意义(P＞0.05).胎儿小脑体积随孕周增加而逐渐增加(r2=0.916,P＜0.05),并与胎头双顶径增长一致(r2=0.877,P＜0.05).结论 三维超声容积测量功能检测胎儿小脑体积重复性好.小脑体积随孕周增加而逐渐增大.所获数据对判断异常具有重要参考意义。

半消化態経腸栄養剤の服用感の評価

The purpose of the present study was to evaluate the palatability of various semi elemental diets using gustatory sensation tests, the equivalent concentration examining method, the SD method, and an artificial taste sensor. The elemental diets studied were New Ensure liquid®, (vanilla flavour, coffee flavour, and strawberry flavour products) a new version of the Enure product which has a different sweetener from the previous product and has been commercially available since 2005, and three older products the previous Ensure liquid® (vanilla, coffee, strawberry), Racol® (milk flavour, coffee flavour, banana flavour), and Harmonic®-M.In testing using the equivalent concentration examining method, the above products were ranked in the following order for sweetness intensity : Harmonic®-M, previous Ensure liquid® product, new Ensure liquid® product, and Racol®.In testing by the SD method, we adopted twenty symmetrical items signifying palatability and in the multiple comparison of these items, there were significant differences in the “Tastes bad-Tastes good” and “Week aftertaste-Strong aftertaste” pairs. A factor analysis of the SD results obtained indicated that “evaluation of taste” and “texture, taste reverberation” items contributed greatly to the first and second factors, respectively. In a scatter graph made from the average factor score for each product, products were well grouped.New Ensure liquid® had a higher factor score for “evaluation of taste” than the other products, but its factor score for “texture, taste reverberation” was lower.The evaluation using the artificial taste sensor showed that protein-based enteral nutrients could be grouped and their palatability predicted.

Patterns of Collapse in Thoracolumbar Burst Fractures

Functional outcomes of neurologically intact patients with burst fractures may be dependent on final kyphosis at the end of treatment. Conservative treatment is indicated if an acceptable sagittal alignment of the spine can be anticipated. Thoracolumbar burst fractures are often grouped as a single entity where, in fact, anatomically distinct areas of the spine may behave differently owing to different biomechanical factors. The goal of this work was to evaluate differential behavior in terms of final kyphosis in anatomically distinct regions of the spine following stable burst fractures. Prospective analysis of kyphosis in 60 patients treated conservatively for traumatic thoracolumbar burst fracture was conducted. Initial trauma supine radiographs were measured for initial kyphosis (Ki). Final kyphosis (Kf) in the upright patient was measured at the end of treatment. The Ki and Kf were plotted on a scatter graph; with use of linear regression analysis, a mathematical model was created to define a relationship between Ki and Kf based on anatomic level of the spine. The thoracolumbar spine behaved in two independent patterns with respect to Kf. Kf at the thoracolumbar junction (T11-L1) had a collapse pattern that could be approximated most accurately with the equation Kf = Ki + 0.5 Ki. At the midlumbar spine, L2-L3 level, a best-fit model for collapse was Kf = Ki + 4 degrees . In this cohort of patients, fractures that were categorized as "stable" and not requiring surgery were studied for the purpose of determining differential collapse patterns in anatomically distinct areas of the lumbar spine. We have demonstrated that the thoracolumbar junction and the midlumbar spine behave differently biomechanically and recommend that these two anatomic levels be studied independently for research purposes.

Intelligent workload control of bicycle ergometer for the elderly based on individual physical work capacity

AbstractStudies on controlling the bicycle ergometer workload for middle‐aged and elderly people by monitoring their heart rate and surface EMG during exercise have been conducted in the past. In this paper, it is shown that 18 middle‐aged and aged subjects studied can be classified into four types in terms of time changes of the indices associated with muscular fatigue, as estimated by tests involving progressively increasing workload. In addition, customization of a workload‐control method for middle‐aged and aged people who show large individual differences in physical work capacities is discussed on the basis of tests of 8 subjects selected from the above types, conducted five times over 9 months. Specifically, scatter graphs of indices associated with muscular fatigue and heart rates measured during progressively increasing workload tests were divided into three intervals and a membership function was designed for fuzzy workload control for each of these intervals. In addition, fuzzy rules considering subjective indices and anaerobic work thresholds are studied while increasing the workload temporarily. The results show that a workload control method that guarantees safety and a feeling of accomplishment can be developed for exercise in the vicinity of the threshold of anaerobic metabolism. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 2, 87(9): 56–64, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjb.20116

Computed Tomography Colonography: Patient Tolerance to CO2 Insufflation

ABSTRACTComputed Tomography (CT) colonography, also known as “virtual colonoscopy” is a relatively new technique for colorectal evaluation. It allows imaging of the colonic mucosa and wall similar to those obtained during conventional colonoscopy. The aim of the present study was to investigate patient tolerance to carbon dioxide (CO2) insufflation during CT colonography and whether the CO2 insufflation was adequate to distend the bowel sufficiently for radiological diagnosis. This study also aimed to demonstrate a relationship between patient age and patient tolerance to CO2 insufflation. This research investigated 22 patients (50 per cent male, mean age 64 years) with a variety of clinical indications. CO2 was insufflated through a rectal catheter to the maximum extent of patient tolerance. Volumetric data of the abdomen and pelvis was acquired in a single breathold using a GE Lightspeed Plus multislice CT scanner with the patient in the supine and prone positions. The CO2 insufflation time for the supine and prone series was recorded and the patients rated their tolerance to the CO2 insufflation based on a modified Likert scale. The results were analysed using scatter graphs and Pearson's Correlation Coefficient, mapping the CO2 insufflation time for the prone and supine series and comparing it to patient age. The findings indicate that there was a statistical significance between patient age and patient tolerance (r=−0.47), however, no statistical significance was found between the other variables. This may be due to several reasons including variable bowel length and a small sample. Additional studies are required with a larger sample in order to further investigate this topic.