Orbital volume analysis: validation of a semi-automatic software segmentation method

Purpose

The purpose of this study was to validate a quick, accurate and reproducible (semi-) automatic software segmentation method to measure orbital volume in the unaffected bony orbit. Precise volume measurement of the orbital cavity is a useful addition to pre-operative planning and intraoperative navigation in orbital reconstruction.

Methods

In 21 CT scans, one unaffected orbit was selected to compare manual segmentation (gold standard) with three segmentation methods using iPlan software (version 3.0.5; Brainlab, Feldkirchen, Germany): automatic (method A), automatic minus bone/air masks (method SA) and automatic minus masks followed by manual adjustments (method SAA). First, validation of the manual segmentation and a newly described method for the anterior boundary was performed. Subsequently the accuracy, reproducibility and time efficiency of the methods were examined. Measurements were performed by two observers.

Results

The intraclass correlation for the interobserver agreement of the anterior boundary was 0.992, and the intraobserver and interobserver agreement for the manual segmentation were 0.997 and 0.994, respectively. Method A had an average volumetric difference of 0.49 cc (SD 0.74) in comparison with the gold standard; this was 0.24 cc (SD 0.27) for method SA and 0.86 cc (SD 0.27) for method SAA. The average time for each method was 38 (SD 5.4), 146 (SD 16.0) and 327 (SD 36.2) seconds per orbit.

Conclusion

The built-in automatic method A is quick, but suboptimal for clinical use. The newly developed method SA appears to be accurate, reproducible, quick and easy to use. Manual adjustments in method SAA are more time-consuming and do not improve volume accuracy. The largest volume discrepancy is located near the inferior orbital fissure.

     

DTI segmentation via the combined analysis of connectivity maps and tensor distances

We describe a novel approach to extract the neural tracts of interest from a diffusion tensor image (DTI). Compared to standard streamline tractography, existing probabilistic methods are able to capture fiber paths that deviate from the main tensor diffusion directions. At the same time, tensor clustering methods are able to more precisely delimit the border of the bundle. To the best of our knowledge, we propose the first algorithm which combines the advantages supplied by probabilistic and tensor clustering approaches. The algorithm includes a post-processing step to limit partial-volume related segmentation errors. We extensively test the accuracy of our algorithm on different configurations of a DTI software phantom for which we systematically vary the image noise, the number of gradients, the geometry of the fiber paths and the angle between adjacent and crossing fiber bundles. The reproducibility of the algorithm is supported by the segmentation of the corticospinal tract of nine patients. Additional segmentations of the corticospinal tract, the arcuate fasciculus, and the optic radiations are in accordance with anatomical knowledge. The required user interaction is comparable to that of streamline tractography, which allows for an uncomplicated integration of the algorithm into the clinical routine.     

用室间质量评价数据评价偏移的不确定度

目的探索室间质量评价(EQA)数据评定偏移的不确定度所需最少次数。方法偏移的相对不确定度(ubias,rel)包括靶值自身相对不确定度(ucref,rel)和实验室相对偏移(RMSbias,rel)。收集2010~2011年上海地区9家使用Roche公司生化指标分析封闭系统的医院20个指标EQA数据,以期望值的20%分析每个医院的ucref,rel或RMSbias,rel达到稳定所需最少次数,并以u检验探讨指标对RMSbias,rel达到稳定的变化趋势的影响。分析所有指标在6次、11次EQA的ubias,rel与末次EQA ubias,rel相对偏移。结果不同指标间RMSbias,rel达到稳定的变化趋势较一致,相同的比例达到94.21%,ucref,rel与RMSbias,rel达到稳定所需最少次数分别占10次与11次。所有医院6次和11次EQA相对偏移≤10%的分析组所占百分比分别占34%和65%。结论 11次以上的EQA数据评定医学实验室偏移的不确定度更有代表性。     

Quantification of left ventricular volume and global function using a fast automated segmentation tool: validation in a clinical setting

Real-time 3D echocardiography (RT3DE) has already been shown to be an accurate tool for left ventricular (LV) volume assessment. However, LV border detection in RT3DE remains a time-consuming task jeopardizing the application of this modality in routine practice. We have recently developed a 3D automated segmentation framework (BEAS) able to capture the LV morphology in real-time. The goal of this study was to assess the accuracy of this approach in extracting volumetric parameters in a clinical setting. 24 RT3DE exams were acquired in a group of healthy volunteers (# = 5) and diseased patients (# = 19), with LV volume/function within a range typically measured in a clinical setting. End-diastolic and end-systolic volumes (EDV, ESV) were manually contoured by 3 expert sonographers from which the stroke volume and ejection fraction (SV, EF) were calculated. The values extracted with BEAS were compared to the average of the 3 experts measurements using correlation and Bland–Altman statistics. Linear regression analysis showed a strong correlation between the automated algorithm and the reference values (R = 0.963, 0.947, 0.944 and 0.853 for EDV, ESV, SV and EF respectively). Bland–Altman analysis revealed a bias (limits of agreement) of 2.59 (?25.39, 30.57) ml, ?2.11 (?24.91, 20.69) ml, 4.70 (12.93, 22.34) ml and 3.45 (?8.96, 15.87) %, for EDV, ESV, SV and EF respectively. Total analysis time using BEAS was 30.7 ± 7.5 s. BEAS allows for a fast and accurate quantification of 3D cardiac volumes and global function with minimal user input. It may therefore contribute to the integration of 3D echocardiography in routine clinical practice.     

Gender bias in the observation of experimental pain

The aim of this study was to examine how men and women observe experimentally induced pain in male and female participants and to specifically determine the accuracy of observed pain ratings, the possible interactions between the sex of the viewer and the sex of the individual being observed, and the influence of gender role expectations on observed pain ratings. The sample comprised 29 participants (15 females). They each completed a battery of psychological questionnaires and viewed a presentation of 10 randomly ordered video clips. Each presentation consisted of 10 video clips, lasting 30s, of a participant (five males and five females) in the cold pressor task. The participants viewing the videos were asked to provide several ratings, including observed pain intensity and gender role related characteristics of the individual in the video. In terms of sex of the video participant, results indicated that viewers rated male videos as having less pain than female videos although the effect was small. Regarding sex of the viewer, results indicated that for both male and female videos, female viewers rated observed pain intensity significantly higher than did male viewers. In terms of accuracy, results indicated that on average, female video participants' pain was underestimated by 14 points, while male videos participants' pain was underestimated by 22 points (on a 0-100-point scale). Pain intensity ratings and pain tolerance from the participants in the videos did not differ significantly with respect to sex, though women had shorter tolerance times and higher pain ratings than men. Hierarchical regression analyses indicated that expectations of gender related 'endurance of pain' significantly predicted ratings of both male and female videos. When endurance expectations were controlled, sex of the viewer no longer significantly predicted observed pain ratings. The 'willingness to report pain' variable was not a significant predictor of observed pain ratings. Our results show that women are perceived to have more pain than men, that there was a tendency by both sexes to underestimate pain in others, but men showed even greater underestimation, and that gender role expectations of pain endurance given by the video observers accounted for substantial variance in their ratings of pain in the videos.     

Testing the fading affect bias for healthy coping in the context of death

Affect fades faster for unpleasant events than for pleasant events (e.g., Walker, Vogl, &; Thompson, 1997 Walker, W. R., Vogl, R. J., &; Thompson, C. P. (1997). Autobiographical memory: Unpleasantness fades faster than pleasantness over time. Applied Cognitive Psychology, 11, 399–413. doi:10.1002/(sici)1099-0720(199710)11:5<399::aid-acp462>3.0.co;2-e[Crossref], [Web of Science ®] , [Google Scholar]), which is referred to as the fading affect bias (FAB; Walker, Skowronski, Gibbons, Vogl, &; Thompson, 2003 Walker, W. R., Skowronski, J. J., Gibbons, J. A., Vogl, R. J., &; Thompson, C. P. (2003). On the emotions that accompany autobiographical memories: Dysphoria disrupts the fading affect bias. Cognition &; Emotion, 17, 703–723. doi:10.1080/02699930302287[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar]). Although research has generally shown that the FAB is a healthy coping mechanism, this same finding has not been demonstrated at a specific level of analysis accounting for particular event types and related individual differences (e.g., Gibbons et al., 2013 Gibbons, J. A., Toscano, A., Kofron, S., Rothwell, C., Lee, S., Ritchie, T., &; Walker, W. R. (2013). The fading affect bias across alcohol consumption frequency for alcohol-related and non-alcohol-related events. Consciousness and Cognition, 22, 1340–1351. doi:10.1016/j.concog.2013.09.004[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Given the strong unpleasant emotions associated with death (Rask, Kaunonen, &; Paunonen-Ilmonen, 2002 Rask, K., Kaunonen, M., &; Paunonen-Ilmonen, M. (2002). Adolescent coping with grief after the death of a loved one. International Journal of Nursing Practice, 8, 137–142. doi:10.1046/j.1440-172X.2002.00354.x[Crossref], [PubMed] , [Google Scholar]), the current study examined FAB in the context of death events and participant attitudes toward death. General healthy coping was shown by robust FAB across death and control (i.e., everyday) events and by a negative correlation between negative religious coping and FAB. Although healthy coping at a specific level of analysis was supported by increased FAB for participants who held accepting attitudes toward death when they recalled everyday events, it was not supported by decreased FAB for the same participants when they recalled death events. This effect was mediated by rehearsal ratings, not depression. Implications are discussed.     

Placenta segmentation in ultrasound imaging: Addressing sources of uncertainty and limited field-of-view

Automatic segmentation of the placenta in fetal ultrasound (US) is challenging due to the (i) high diversity of placenta appearance, (ii) the restricted quality in US resulting in highly variable reference annotations, and (iii) the limited field-of-view of US prohibiting whole placenta assessment at late gestation. In this work, we address these three challenges with a multi-task learning approach that combines the classification of placental location (e.g., anterior, posterior) and semantic placenta segmentation in a single convolutional neural network. Through the classification task the model can learn from larger and more diverse datasets while improving the accuracy of the segmentation task in particular in limited training set conditions. With this approach we investigate the variability in annotations from multiple raters and show that our automatic segmentations (Dice of 0.86 for anterior and 0.83 for posterior placentas) achieve human-level performance as compared to intra- and inter-observer variability. Lastly, our approach can deliver whole placenta segmentation using a multi-view US acquisition pipeline consisting of three stages: multi-probe image acquisition, image fusion and image segmentation. This results in high quality segmentation of larger structures such as the placenta in US with reduced image artifacts which are beyond the field-of-view of single probes.     

Accuracy validation and bias assessment for various multi-sensor open-source DEMs in part of the Karakoram region

ABSTRACT

The present study evaluate horizontal and vertical accuracy of seven open-source digital elevation models (DEMs) having moderate-to-high resolutions viz. 30 m Shuttle Radar Topography Mission (SRTM1), Advanced Spaceborne Thermal Emission and Reflection Radiometer Global DEM (ASTER GDEM), Advanced Land Observing Satellite World 3D (AW3D30), and Cartosat DEM (CartoDEM), 90 m TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-X), 12.5 m terrain corrected Phased Array L-band Synthetic Aperture Radar (PALSAR) from Advanced Land Observing Satellite (ALOS) and 8 m High Mountain Asia (HMA) over the rugged mountainous terrain of the Karakoram region. Horizontal accuracy (specified in x and y) assessed by referring photogrammetrically generated master DEM from Cartosat-1 revealed AW3D30 as the most consistent DEM with a slight shift of +2.80 m and ?4.89 m in x and y direction, respectively. However, vertical accuracy analysis showed that both HMA and AW3D30 DEMs are quite close to each other with MAE of 3.01 m and 3.46 m, RMSE of 5.6 m and 7.5 m, and NMAD of 4.09 m and 5.5 m, respectively. We also examined the influence of slope on DEM errors and associated elevation-dependent bias over non-glaciated surface which can be valuable input for geodetic mass balance estimations.     

Longitudinal loss of gray matter volume in patients with first-episode schizophrenia: DARTEL automated analysis and ROI validation

Region of Interest (ROI) longitudinal studies have detected progressive gray matter (GM) volume reductions in patients with first-episode schizophrenia (FESZ). However, there are only a few longitudinal voxel-based morphometry (VBM) studies, and these have been limited in ability to detect relationships between volume loss and symptoms, perhaps because of methodologic issues. Nor have previous studies compared and validated VBM results with manual Region of Interest (ROI) analysis.In the present VBM study, high-dimensional warping and individualized baseline-rescan templates were used to evaluate longitudinal volume changes within subjects and compared with longitudinal manual ROI analysis on the same subjects. VBM evaluated thirty-three FESZ and thirty-six matched healthy control subjects (HC) at baseline (cross-sectionally) and longitudinally evaluated 21 FESZ and 23 HC after an average of 1.5 years from baseline scans. Correlation analyses detected the relationship between changes in regional GM volumes in FESZ and clinical symptoms derived from the Brief Psychiatric Rating Scale, as well as cognitive function as assessed by the Mini-Mental State Examination.At baseline, patients with FESZ had significantly smaller GM volume compared to HC in some regions including the left superior temporal gyrus (STG). On rescan after 1.5 years, patients showed significant GM volume reductions compared with HC in the left STG including Heschl's gyrus, and in widespread brain neocortical regions of frontal, parietal, and limbic regions including the cingulate gyrus. FESZ showed an association of positive symptoms and volume loss in temporal (especially STG) and frontal regions, and negative symptoms and volume loss in STG and frontal regions. Worse cognitive function was linked to widespread volume reduction, in frontal, temporal and parietal regions. The validation VBM analyses showed results similar to our previous ROI findings for STG and cingulate gyrus. We conclude FESZ show widespread, progressive GM volume reductions in many brain regions. Importantly, these reductions are directly associated with a worse clinical course. Congruence with ROI analyses suggests the promise of this longitudinal VBM methodology.     

Comparative validation of multi-instance instrument segmentation in endoscopy: Results of the ROBUST-MIS 2019 challenge

Intraoperative tracking of laparoscopic instruments is often a prerequisite for computer and robotic-assisted interventions. While numerous methods for detecting, segmenting and tracking of medical instruments based on endoscopic video images have been proposed in the literature, key limitations remain to be addressed: Firstly, robustness, that is, the reliable performance of state-of-the-art methods when run on challenging images (e.g. in the presence of blood, smoke or motion artifacts). Secondly, generalization; algorithms trained for a specific intervention in a specific hospital should generalize to other interventions or institutions.In an effort to promote solutions for these limitations, we organized the Robust Medical Instrument Segmentation (ROBUST-MIS) challenge as an international benchmarking competition with a specific focus on the robustness and generalization capabilities of algorithms. For the first time in the field of endoscopic image processing, our challenge included a task on binary segmentation and also addressed multi-instance detection and segmentation. The challenge was based on a surgical data set comprising 10,040 annotated images acquired from a total of 30 surgical procedures from three different types of surgery. The validation of the competing methods for the three tasks (binary segmentation, multi-instance detection and multi-instance segmentation) was performed in three different stages with an increasing domain gap between the training and the test data. The results confirm the initial hypothesis, namely that algorithm performance degrades with an increasing domain gap. While the average detection and segmentation quality of the best-performing algorithms is high, future research should concentrate on detection and segmentation of small, crossing, moving and transparent instrument(s) (parts).     

4层螺旋CT有效层厚的理论分析与实验测定

目的 通过建立数学模型,分析4层螺旋CT有效层厚的计算方法 ,并与理论计算值比较.方法 假设螺旋层灵敏度曲线(SSP)为高斯分布,SSP的半高宽(FWHM)为有效层厚,通过分析推导出采用180°线性插值法4层螺旋CT有效层厚的计算公式.使用Philips Mx 8000 4层螺旋CT对Catphan 500 CT模体的CTP 528模块进行扫描,扫描参数:管电压120 kV,管电流量150 mAs,探测器宽度0.5 mm,FOV 180 mm,重建矩阵512×512,180°线性插值,分别使用不同的螺距和探测器宽度进行扫描和重建.对于每一图像序列进行冠状位多平面重组,在经过CTP 528模块的钨质小球中心的MPR影像上测量出有效层厚.结果 采用螺距0.500、0.625、0.875、1.000、1.250、1.500、1.750测得的有效层厚分别是0.7、0.7、0.7、0.8、0.7、0.7、0.7 mm;采用探测器宽度0.5、1.0、5.0 mm测得的有效层厚分别是0.7、1.2、6.7 mm.有效层厚的实验测定值均大于理论计算值.结论 4层螺旋CT有效层厚与探测器宽度成正比;与螺距呈复杂的曲线变化关系,存在极大值和极小值.     

Performance of iohexol determination in serum and urine by HPLC: validation, risk and uncertainty assessment

BACKGROUND: Determination of glomerular filtration rate plays an important role in nephrological practice. Iohexol is a reference marker for glomerular filtration rate determination. It is available and safe. The aim of this study was to develop a simple, efficient and easy to use analytical method for the quantification of iohexol in serum and urine by high performance liquid chromatography and to thoroughly validate this method. METHODS: The HPLC method was inspired from the method published by Krutzen. The e.noval software V2.0 (Arlenda, Liège, Belgium) was used to compute all validation results. RESULTS: The validation results indicate that the method will give accurate and reliable results for serum values ranging from 12.95 to 1295 microg/ml and for urine values ranging from 86.0 to 4144 microg/ml. In routine practice, iohexol concentrations found in plasma after injection range from 40 to 600 microg/ml. The expected urinary values are much wider. One should not hesitate to dilute urine samples to fit with the validated range over 5000 microg/ml. CONCLUSION: This is the first time that a reference method for the determination of GFR is validated with such a rigorous and thorough protocol. Contrary to other GFR markers, iohexol is now strongly validated from an analytical point of view.     

Methylation-sensitive high-resolution melting in the context of legislative requirements for validation of analytical procedures for diagnostic applications

Temperature gradient was first used to identify the methylation status of the DNA sequence over 10 years ago; however, the initially published protocol was shown to have poor analytical sensitivity. Recent developments in the field of DNA melting technologies, combined with the identification of procedures to overcome the sensitivity issues in the PCR-based methylation detection applications, led to the development of the methylation-sensitive high-resolution melting (MS-HRM) protocol. This protocol allows for highly sensitive detection of methylation levels in a labor- and cost-efficient fashion. Moreover, it enables investigation of methylation status of imprinted loci as well as identification of heterogeneous methylation. The MS-HRM technology is being increasingly applied in research laboratories and has a potential for future application in diagnostic settings. The focus of this article is to describe the development of the HRM technology for methylation analyses and evaluate the diagnostic applicability of the MS-HRM technology.     

Three-dimensional echocardiographic measurement of left and right ventricular mass and volume: in vitro validation

Introduction: Three-dimensional (3D) echocardiography has been shown to offer highly accurate measurements of left ventricular (LV) volume and mass. The present study evaluated the accuracy of 3D surface reconstruction by the piecewise smooth subdivision method in measuring volume and mass not only in the LV but also in the more complexly shaped right ventricle (RV). Methods: 3D echo scans were obtained of in vitro LV's (n = 15) and RVs (n = 10). From digitized images, ventricular borders were traced and used in surface reconstructions. Mass and volume determined from the reconstructions were compared to true volume and mass determined prior to imaging. Additionally casts of two RVs were made and laser-scanned. Distances between the laser-identified points on the RV surface and the corresponding 3D echo reconstructions were measured. Results: 3D LV volume agreed well with the true volume (y = 0.99x + 1.73, r = 0.99, SEE = 3.35 ml, p < 0.0001), as did 3D LV mass (y = 0.99x – 4.71, r = 0.99, SEE = 9.85 g, p < 0.0001). 3D RV volume overestimated true volume (y = 1.11x + 1.77, r = 0.99, SEE = 3.36 ml, p < 0.001) by 6.23 ± 3.70 ml (p < 0.0001). 3D mass agreed well with RV mass (y = 0.78x + 17.32, r ² = 0.93, SEE = 3.54 g, p < 0.0001). 3D echo reconstructions matched the laser-scanned RV closely with residual distances of 1.1 ± 0.9 and 1.4 ± 1.2 mm, respectively. Conclusions: 3D echo using freehand scanning combined with surface reconstruction by the piecewise smooth subdivision surface method enables accurate determination of LV mass and volume, of RV mass and volume, and of the RV's complex shape.     

Stigma in the context of hepatitis C: concept analysis

Title.  Stigma in the context of hepatitis C: concept analysis.
Aim.  This paper is a report of a concept analysis of stigma in the context of hepatitis C.
Background.  Stigma is a complex and powerful social phenomenon that influences the course of illness and marginalizes populations. Knowledge of hepatitis C stigma is central to assisting people with hepatitis C self-manage their illness and reduce the disease burden.
Data sources.  Thirty studies from 1995 to 2007 located in health and social sciences databases constituted the data for an evolutionary concept analysis and ecological theory guide the review.
Findings.  Stigma is a subjective and variable, perceived and/or experienced phenomenon, most frequently but not exclusively viewed as negative, that has interrelated intrapersonal, interpersonal and structural or institutional dimensions. The antecedents of hepatitis C stigma are help-seeking situations most frequently occurring in healthcare settings. Attributes include the association of hepatitis C with illicit drug use, fear of transmission of a contagious and life-threatening infection, acceptable level of risk, and the power to impose restrictions on the part of healthcare practitioners, family and friendship networks and society. Stigma consequences are mainly, but not exclusively, negative.
Conclusion.  A central and distinctive feature of hepatitis C stigma in the Western world is its association with illicit drug use. Further research is required to understand the complexities associated with the sociocultural, situational and structural features that influence the stigma experience as well as the trajectory of the disease to understand the concept better and inform nursing practice.     

A hermeneutic textual analysis of suffering and caring in the peri-operative context

Hermeneutic text interpretation is discussed in this paper as a possible way of releasing nurses' knowledge, in order to develop a deeper understanding of professional caring. The text is a nurse's story, which has been gathered by means of the critical incident technique. The intention is to elicit the knowledge of professional caring in the stories and the language of caring science, which is concealed in a nurse's reality. Hermeneutic text interpretation through reading a text and having a dialogue with the nurse's reality will give a voice and a language to silent knowledge.