The reliability of measuring physical characteristics of spiculated masses on mammography

Scale-Free Dynamics in Instantaneous Alpha Frequency Fluctuations: Validation, Test-Retest Reliability and Its Relationship with Task Manipulations

Previous studies showed that scale-free structures and long-range temporal correlations are ubiquitous in physiological signals (e.g., electroencephalography). This is supposed to be associated with optimized information processing in human brain. The instantaneous alpha frequency (IAF) (i.e., the instantaneous frequency of alpha band of human EEG signals) may dictate the resolution at which information is sampled and/or processed by cortical neurons. To the best of our knowledge, no research has examined the scale-free dynamics and potential functional significance of IAF. Here, through three studies (Study 1: 25 participants; Study 2: 82 participants; Study 3: 26 participants), we investigated the possibility that time series of IAF exhibit scale-free property through maximum likelihood based detrended fluctuation analysis (ML-DFA). This technique could provide the scaling exponent (i.e., DFA exponent) on the basis of presence of scale-freeness being validated. Then the test-retest reliability (Study 1) and potential influencing factors (Study 2 and Study 3) of DFA exponent of IAF fluctuations were investigated. Firstly, the scale-free property was found to be inherent in IAF fluctuations with fairly high test-retest reliability over the parietal-occipital region. Moreover, the task manipulations could potentially modulate the DFA exponent of IAF fluctuations. Specifically, in Study 2, we found that the DFA exponent of IAF fluctuations in eye-closed resting-state condition was significantly larger than that in eye-open resting-state condition. In Study 3, we found that the DFA exponent of IAF fluctuations in eye-open resting-state condition was significantly larger than that in visual n-back tasks. The DFA exponent of IAF fluctuations in the 0-back task was significantly larger than in the 2-back and 3-back tasks. The results in studies 2 and 3 indicated that: (1) a smaller DFA exponent of IAF fluctuations should signify more efficient online visual information processing; (2) the scaling property of IAF fluctuations could reflect the physiological arousal level of participants.

Indoor air quality in the primary school of China-results from CIEHS 2018 study

Indoor air quality ((IAQ) in classrooms was associated with the daily exposure of school-age children who are particularly vulnerable to air pollutants exposure, while few data exist to evaluate classroom indoor air quality nationwide in China. The subsample of the CIEHS 2018 study was performed in 66 classrooms of 22 primary schools nationwide in China. Temperature, relative humidity, PM_2.5, PM₁₀, CO₂, CO, formaldehyde concentrations, bacteria and fungi were detected in all classrooms by using the instruments that meet the specified accuracy. The ratios of indoor to outdoor (I/O) of PM_2.5 were calculated in each classroom to identify whether the indoor environment the pollutants comes from outdoors. The indoor PM_2.5, PM₁₀, CO, HCHO, bacteria and fungi GM concentration are 47.40 μg/m³, 72.91 μg/m³, 0.37 mg/m³, 0.02 mg/m³, 347.51 CFU/m³ and 362.76 CFU/m³, respectively. We observed that there were 66.5%, 52.6%, 22.4%, 1.8%, and 9.6% of the classrooms that exceeded the guideline values of PM_2.5, PM₁₀, CO₂, HCHO, and bacteria, respectively. It should be attention that all of the classroom's PM_2.5 concentrations in Shijiazhuang and Nanning, PM₁₀ concentrations in Nanning, CO₂ concentration in Lanzhou were exceeded the suggested values. Bacteria contamination in Shijiazhuang's classrooms is also serious. All classroom CO concentrations meet the requirement. The results indicated that classroom indoor PM_2.5 was significantly positively correlated with indoor PM₁₀ and CO₂, while was negative correlated with temperature, CO, and fungi. Our results suggest that indoor air pollution in classrooms was a severe problem in Chinese primary schools. It is necessary to strengthen ventilation in the classroom to improve indoor air quality. What's more, a healthy learning environment should be created for primary school students.

Spatiotemporal variation in residential PM2.5 and PM10 concentrations in China: National on-site survey

BACKGROUND

Significant efforts have been directed toward addressing the adverse health effects of particulate matter, while few data exist to evaluate indoor exposure nationwide in China.

OBJECTIVES

This study aimed to investigate dwellings particulate matter levels in the twelve cities in China and provide large data support for policymakers to accelerate the legislative process.

METHODS

The current study was based on the CIEHS 2018 study and conducted in 12 cities of China. A total of 2128 air samples were collected from 610 residential households during the summer and winter. Both PM₁₀ and PM_2.5 were detected with a light-scattering dust meter in both the living room and bedroom. The Wilcoxon rank-sum test was performed to evaluate the correlations between PM_2.5 and PM₁₀ concentrations and both sampling season and site. Ratios of the living room to bedroom were calculated to evaluate the particulate matter variation between rooms. Hierarchical clustering was used to probe the question of whether the concentration varies between cities throughout China.

RESULTS

The geometric means of the PM_2.5 in living rooms and bedrooms were 39.80 and 36.55 μg/m³ in the summer, and 70.97 and 67.99 μg/m³ in the winter, respectively. In the summer, approximately 70 % of indoor dwelling PM_2.5 exceeded the limit of 25 μg/m³, and for PM₁₀ approximately 60 % of dwellings demonstrated levels higher than 50 μg/m³; the corresponding values were over 90 % and 80 % in winter, respectively. In Shijiazhuang, Lanzhou, Luoyang and Qingdao, the geometric means of the PM_2.5 concentrations were observed to be 1.5 to 4.3 times higher during winter than during summer; similar concentrations in summer and winter were observed in Harbin, Wuxi, and Shenzhen, while the PM_2.5 concentrations in Panjin were approximately 1.5 times higher in summer than in winter. There was no significant difference in particulate matter concentrations between the living rooms and bedrooms. Scatter plots showed that cities with low GDP and a small population had higher concentrations, while Shenzhen, which has a higher GDP and a large permanent population, had a relatively low concentration of particulate matter.

CONCLUSIONS

Our results suggest that indoor air pollution is a severe problem in China. It is necessary to continue monitoring indoor air quality to observe the changing trend under the tremendous effort of the Chinese government.

Association of Pericoronary Adipose Tissue Quality Determined by Dual-Layer Spectral Detector CT With Severity of Coronary Artery Disease: A Preliminary Study

Background: Pericoronary adipose tissue (PCAT) is considered as a source of inflammatory mediators, leading to the development of coronary atherosclerosis. The study aimed to investigate the correlation between PCAT quality derived from dual-layer spectral detector CT (SDCT) and the severity of coronary artery disease (CAD), and whether PCAT parameters were independently associated with the presence of CAD.

Materials and Methods: A total of 403 patients with symptoms of chest pain who underwent SDCT were included. PCAT quality including fat attenuation index (FAI) measured from conventional polychromatic CT images (FAI_120kvp) and spectral virtual mono-energetic images at 40 keV (FAI_40keV), slope of spectral HU curve (λ_HU), and effective atomic number (Eff-Z) were measured around the lesions representing the maximal degree of vascular stenosis in each patient. Meanwhile, overall epicardial adipose tissue (EAT) attenuation was acquired in the conventional polychromatic energy imaging.

Results: FAI_40keV, λ_HU, Eff-Z, and FAI_120kvp increased along with the degree of CAD in general and were superior to the overall EAT attenuation for detecting the presence of CAD. Multivariate logistic regression analysis indicated that FAI_40keV was the most powerful independent indicator (odds ratio 1.058, 95% CI 1.044–1.073; p < 0.001) of CAD among these parameters. Using an optimal cut-off (−131.8 HU), FAI_40keV showed higher diagnostic accuracy of 80.6% compared with the other parameters.

Conclusions: These preliminary findings suggest that FAI_40keV on SDCT may be an appealing surrogate maker to allow monitoring of PCAT changes in the development of CAD.

Identification of robust and reproducible CT-texture metrics using a customized 3D-printed texture phantom

OBJECTIVE

The objective of this study was to evaluate the robustness and reproducibility of computed tomography-based texture analysis (CTTA) metrics extracted from CT images of a customized texture phantom built for assessing the association of texture metrics to three-dimensional (3D) printed progressively increasing textural heterogeneity.

MATERIALS AND METHODS

A custom-built 3D-printed texture phantom comprising of six texture patterns was used to evaluate the robustness and reproducibility of a radiomics panel under a variety of routine abdominal imaging protocols. The phantom was scanned on four CT scanners (Philips, Canon, GE, and Siemens) to assess reproducibility. The robustness assessment was conducted by imaging the texture phantom across different CT imaging parameters such as slice thickness, field of view (FOV), tube voltage, and tube current for each scanner. The texture panel comprised of 387 features belonging to 15 subgroups of texture extraction methods (e.g., Gray-level Co-occurrence Matrix: GLCM). Twelve unique image settings were tested on all the four scanners (e.g., FOV125). Interclass correlation two-way mixed with absolute agreement (ICC3) was used to assess the robustness and reproducibility of radiomic features. Linear regression was used to test the association between change in radiomic features and increased texture heterogeneity. Results were summarized in heat maps.

RESULTS

A total of 5612 (23.2%) of 24 090 features showed excellent robustness and reproducibility (ICC ≥ 0.9). Intensity, GLCM 3D, and gray-level run length matrix (GLRLM) 3D features showed best performance. Among imaging variables, changes in slice thickness affected all metrics more intensely compared to other imaging variables in reducing the ICC3. From the analysis of linear trend effect of the CTTA metrics, the top three metrics with high linear correlations across all scanners and scanning settings were from the GLRLM 2D/3D and discrete cosine transform (DCT) texture family.

CONCLUSION

The choice of scanner and imaging protocols affect texture metrics. Furthermore, not all CTTA metrics have a linear association with linearly varying texture patterns.

Painful type II os naviculare: introduction of a standardized, reproducible classification system

OBJECTIVE

To provide a novel MRI classification system for the symptomatic type II os naviculare by creating a standardized grading of associated bone marrow edema (BME) and correlating with patient symptoms.

METHODS

BME was classified on an ordinal scale: grade 1, faint signal immediately adjacent to the synchondrosis; grade 2, intermediate signal within the os and navicular tuberosity without extending to the navicular body; grade 3, intense signal extending to the navicular body. BME on 59 MRIs was independently graded by three radiologists. Inter- and intra-observer agreement was analyzed using intraclass correlation coefficient. Univariate and multivariate analyses assessed for patient and imaging characteristics predictive of subjective pain score. A cohort of 82 patients without BME represented a control group.

RESULTS

Inter-observer agreement of BME grade was 0.95 (CI 0.93-0.97) and intra-observer was 0.92 (CI 0.87-0.96), indicating excellent agreement. In patients with BME, predictors of more severe pain were longer duration of pain (p = 0.02) and presence of soft tissue edema overlying the os naviculare (p < 0.001). One hundred percent of subjects with BME localized their pain to the medial midfoot (59/59) versus 25.6% (21/82) of controls (p < 0.001).

CONCLUSIONS

This novel grading system provides reliable quantification of BME associated with os naviculare, which is a specific cause of medial foot/ankle pain. Early diagnosis is important as pain severity worsens with longer duration of symptoms. Pain severity is correlated with soft tissue edema overlying the os, which may be secondary to extrinsic compression, reactive to biomechanical stress, or reflect direct trauma.

Deep learning can be used to train naïve, nonprofessional observers to detect diagnostic visual patterns of certain cancers in mammograms: a proof-of-principle study

The scientific, clinical, and pedagogical significance of devising methodologies to train nonprofessional subjects to recognize diagnostic visual patterns in medical images has been broadly recognized. However, systematic approaches to doing so remain poorly established. Using mammography as an exemplar case, we use a series of experiments to demonstrate that deep learning (DL) techniques can, in principle, be used to train naïve subjects to reliably detect certain diagnostic visual patterns of cancer in medical images. In the main experiment, subjects were required to learn to detect statistical visual patterns diagnostic of cancer in mammograms using only the mammograms and feedback provided following the subjects’ response. We found not only that the subjects learned to perform the task at statistically significant levels, but also that their eye movements related to image scrutiny changed in a learning-dependent fashion. Two additional, smaller exploratory experiments suggested that allowing subjects to re-examine the mammogram in light of various items of diagnostic information may help further improve DL of the diagnostic patterns. Finally, a fourth small, exploratory experiment suggested that the image information learned was similar across subjects. Together, these results prove the principle that DL methodologies can be used to train nonprofessional subjects to reliably perform those aspects of medical image perception tasks that depend on visual pattern recognition expertise.

Altered Directed Functional Connectivity of the Hippocampus in Mild Cognitive Impairment and Alzheimer's Disease: A Resting-State fMRI Study

The hippocampus is generally reported as one of the regions most impacted by Alzheimer’s disease (AD) and is closely associated with memory function and orientation. Undirected functional connectivity (FC) alterations occur in patients with mild cognitive impairment (MCI) and AD, and these alterations have been the subject of many studies. However, abnormal patterns of directed FC remain poorly understood. In this study, to identify changes in directed FC between the hippocampus and other brain regions, Granger causality analysis (GCA) based on voxels was applied to resting-state functional magnetic resonance imaging (rs-fMRI) data from 29 AD, 65 MCI, and 30 normal control (NC) subjects. The results showed significant differences in the patterns of directed FC among the three groups. There were fewer brain regions showing changes in directed FC with the hippocampus in the MCI group than the NC group, and these regions were mainly located in the temporal lobe, frontal lobe, and cingulate cortex. However, regarding the abnormalities in directed FC in the AD group, the number of affected voxels was greater, the size of the clusters was larger, and the distribution was wider. Most of the abnormal connections were unidirectional and showed hemispheric asymmetry. In addition, we also investigated the correlations between the abnormal directional FCs and cognitive and clinical measurement scores in the three groups and found that some of them were significantly correlated. This study revealed abnormalities in the transmission and reception of information in the hippocampus of MCI and AD patients and offer insight into the neurophysiological mechanisms underlying MCI and AD.

Reliability evaluation on weighted graph metrics of fNIRS brain networks

Background

Resting-state fNIRS (R-fNIRS) imaging data has proven to be a valuable technique to quantitatively characterize functional architectures of human brain network. However, whether the brain network metrics derived using weighted brain network model is test-retest (TRT) reliable remains largely unknown.

Methods

Here, we firstly constructed weighted brain networks on a group of 18 participants, and then applied graph-theory approach to quantify topological parameters of each weighted network. The intraclass correlation coefficient (ICC) was further applied to quantify the TRT reliability of network metrics.

Results

We found that the reliability of the weighted network metrics is threshold-sensitive, and most of these network metrics showed fair to excellent reliability. Specifically, the global network metrics, e.g., clustering coefficient, path length, local efficiency and global efficiency were of excellent level reliability (ICC >0.75) on both HbO and HbR signals. The nodal network metrics, e.g., degree and efficiency, generally also showed excellent level reliability on both HbO and HbR signals, and the reliability of these two metrics was better than that of nodal betweenness.

Conclusions

Overall, these findings demonstrated that most weighted network metrics derived from fNIRS are TRT reliable and can be used for brain network research.

The efficacy of cervical spine phantoms for improving resident proficiency in performing ultrasound-guided cervical medial branch block: A prospective, randomized, comparative study

BACKGROUND

Few studies have been conducted on the utility of cervical spine phantoms for practicing cervical procedures. Here, we describe a simple method for creating a cervical spine phantom and investigate whether the use of a gelatin-based phantom is associated with improved proficiency in performing ultrasound-guided cervical medial branch block.

METHODS

A cervical spine phantom was prepared using a cervical spine model immersed in a mixture of gelatin and psyllium husk. In total, 27 participants, inexperienced in spinal ultrasonography, were enrolled and allocated to 1 of 2 groups (training group, n = 18; control group, n = 9). All participants were tested (test-1) following an introductory course of basic ultrasonography. Participants in the control group were tested again after 1 week (test-2). Those in the training group received a further individual 3-hour training session, and were tested again after 1 week (test-2).

RESULTS

The mean performance score in test-1 was 62.5 ± 10.1 points in the training group and 62.3 ± 4.1 points in the control group [95% confidence interval (95% CI) -5.5 to 5.8; P = .954]. In test-2, the mean score was 86.8 ± 6.5 points and 59.9 ± 4.4 points in the training and control groups, respectively (95% CI 21.9-31.8; P < .001). The mean time required to complete test-1 was 84.6 ± 26.6 seconds in training group and 90.7 ± 43.9 seconds in the control group (95% CI -34.0 to 21.7; P = .653); in test-2, the time required was 56.6 ± 27.9 and 91.2 ± 43.8 seconds (95% CI -63.0 to -6.2; P = .019), respectively. Interobserver reliability showed excellent agreement based on the intraclass correlation coefficient, and moderate to almost perfect agreement by kappa statistics.

CONCLUSION

Training using a gelatin-based cervical spine phantom helps novices acquire the skills necessary to perform ultrasound-guided cervical medial branch blocks.

Test-retest Reliability of Functional Connectivity and Graph Metrics in the Resting Brain Network

The combination of graph theoretical approaches and neuroimaging data provides a powerful way to explore the characteristics of brain network. Recently, the temporal variability of spontaneous brain activity and functional connectivity has attracted wide attention. Thus, it is essential to evaluate the reliability of functional network connectivity and properties from the dynamic perspective. However, previous test-retest (TRT) studies have explored this reliability with a static point of view. In this study, using a large rs-fMRI dataset from Human Connectome Project (HCP), we investigated TRT reliability of functional connectivity and graph metrics derived from the most commonly used method- sliding window at three time intervals (short: 72 seconds, middle: 15 minutes and long: >24 hours). The results revealed that reliable connectivities and related brain regions are mainly distributed in primary cortex, such as visual area and sensorimotor area and default mode network. Notably, connectivity strength and global efficiency have better reliability than other metrics. Finally, short scan time interval and long scan duration can increase the TRT reliability of metrics. Findings of present study provide important guidance for searching reliable network markers in future research.

Breast lesion shape and margin evaluation: BI-RADS based metrics understate radiologists' actual levels of agreement

BACKGROUND

While there is much literature describing the radiologic detection of breast cancer, there are limited data available on the agreement between experts when delineating and classifying breast lesions. The aim of this work is to measure the level of agreement between expert radiologists when delineating and classifying breast lesions as demonstrated through Breast Imaging Reporting and Data System (BI-RADS) and quantitative shape metrics.

METHODS

Forty mammographic images, each containing a single lesion, were presented to nine expert breast radiologists using a high specification interactive digital drawing tablet with stylus. Each reader was asked to manually delineate the breast masses using the tablet and stylus and then visually classify the lesion according to the American College of Radiology (ACR) BI-RADS lexicon. The delineated lesion compactness and elongation were computed using Matlab software. Intraclass Correlation Coefficient (ICC) and Cohen's kappa were used to assess inter-observer agreement for delineation and classification outcomes, respectively.

RESULTS

Inter-observer agreement was fair for BI-RADS shape (kappa = 0.37) and moderate for margin (kappa = 0.58) assessments. Agreement for quantitative shape metrics was good for lesion elongation (ICC = 0.82) and excellent for compactness (ICC = 0.93).

CONCLUSIONS

Fair to moderate levels of agreement was shown by radiologists for shape and margin classifications of cancers using the BI-RADS lexicon. When quantitative shape metrics were used to evaluate radiologists' delineation of lesions, good to excellent inter-observer agreement was found. The results suggest that qualitative descriptors such as BI-RADS lesion shape and margin understate the actual level of expert radiologist agreement.

Reliability and validity study of the Gujarati version of the Oswestry Disability Index 2.1a

BACKGROUND

Among all musculoskeletal disorders back pain is the most common reason for functional limitation in working age. It is due to low back pain (LBP) that the ODI has become one of the principal outcome measures for evaluation of disability and has been widely used in research as well as in clinical practice. So far, validated Gujarati version of the ODI 2.1a has not been reported.

OBJECTIVE

To accomplish the translation and validation of the Oswestry Disability Index (ODI) version 2.1a into the Gujarati language.

STUDY DESIGN

Cross-sectional study.

METHODS

The validation of the ODI-Gujarati was tested in 120 patients diagnosed with non-specific LBP, who were receiving physiotherapy at a clinic in Gujarat, India. Data was collected at on initial visit and after 48 hours. During both visits, patients completed the Oswestry Disability Index-Gujarati (ODI-G), Roland-Morris Disability Questionnaire-Gujarati (RMDQ-G), and Visual Analogue Scale-Pain (VAS-P).

RESULTS

Internal consistency was measured by Cronbach's alpha. The Gujarati version indicated high internal consistency (α= 0.96). Test-retest reliability was measured by intra-class correlation coefficient and it revealed very high correlation (ICC = 0.92). Construct validity was confirmed by strong correlation with RMDQ-G (r= 0.76), and concurrent validity indicated moderate correlation with VAS-P (r= 0.50). Factor analysis explained that the ODI was loaded on 1 factor.

CONCLUSION

The Oswestry disability index version 2.1a was successfully translated into Gujarati language, showing excellent psychometric properties. Therefore, it can be used in evaluating the disability amongst Gujarati population with LBP for both clinical and research purposes.

Modification of the alignment between the tibial tubercle and the trochlear groove induced by temporary hemiepiphysiodesis for lower extremity angular deformities: a trigonometric analysis

This study aimed to predict the modification of the alignment between the tibial tubercle (TT) and the trochlear groove (TG) that occurs during femoral or tibial hemiepiphysiodesis. MRI scans of 541 knees were retrospectively reviewed to determine the distances between the cranial insertion of the patellar tendon on the TT and the femoral physis (FP)/tibial physis (TP). Thereafter, we developed a trigonometric formula to calculate the predicted change of the TT-TG distance that occurs during hemiepiphysiodesis around the knee using both the planned angular correction as well as the length between the physis (both distal femoral and proximal tibial) and the insertion of the patellar tendon of the TT. This study showed that TT-FP and TT-TP distances vary very little with sex and age during growth and the mean values of FP-TT and TP-TT distances (55 and 7 mm, respectively) can thus be used in clinical settings for calculating a rough estimate of the translation of the TT position that will occur during 'guided growth'. On this subject, one can expect a 1 mm simultaneous lateral or medial transfer of the TT for every 1° of angular correction during distal femoral hemiepiphysiodesis. For proximal tibial hemiepiphysiodesis, an angular correction of 8° should roughly translate into a simultaneous 1 mm transfer of the TT. This study puts forward the hypothesis that a simultaneous modification of the TT-TG distance has to be expected following hemiepiphysiodesis, whether femoral or tibial.

LEVEL OF EVIDENCE

III.

Validation of a Dish-Based Semiquantitative Food Questionnaire in Rural Bangladesh

A locally validated tool was needed to evaluate long-term dietary intake in rural Bangladesh. We assessed the validity of a 42-item dish-based semi-quantitative food frequency questionnaire (FFQ) using two 3-day food diaries (FDs). We selected a random subset of 47 families (190 participants) from a longitudinal arsenic biomonitoring study in Bangladesh to administer the FFQ. Two 3-day FDs were completed by the female head of the households and we used an adult male equivalent method to estimate the FD for the other participants. Food and nutrient intakes measured by FFQ and FD were compared using Pearson's and Spearman's correlation, paired t-test, percent difference, cross-classification, weighted Kappa, and Bland-Altman analysis. Results showed good validity for total energy intake (paired t-test, p < 0.05; percent difference <10%), with no presence of proportional bias (Bland-Altman correlation, p > 0.05). After energy-adjustment and de-attenuation for within-person variation, macronutrient intakes had excellent correlations ranging from 0.55 to 0.70. Validity for micronutrients was mixed. High intraclass correlation coefficients (ICCs) were found for most nutrients between the two seasons, except vitamin A. This dish-based FFQ provided adequate validity to assess and rank long-term dietary intake in rural Bangladesh for most food groups and nutrients, and should be useful for studying dietary-disease relationships.

Acute benign vertebral compression fractures: "see-through sign" on contrast-enhanced MR images

PURPOSE

To retrospectively evaluate the diagnostic role of the contrast-enhanced MRI (CE-MRI) for differentiation between benign VCFs and malignant VCFs focusing on the internal transparent trabecular bone on CE-MRI (the "see-through sign").

MATERIALS AND METHODS

The institutional review board approved this study and informed consent was waived due to the retrospective nature of the study. From January 2012 to December 2013, all 149 consecutive benign or malignant VCF patients were enrolled for consideration in this study from a CE-MRI database. In the first analysis, four radiologists independently evaluated the presence or absence of the see-through sign. The see-through sign was defined as internal transparent trabecular bone morphology on CE-MRI. The intraclass correlation coefficient (ICC), percentage agreement, and Fleiss's kappa statistics were obtained.

RESULTS

Fifty-seven patients (M:F = 27:30; mean age, 63 years; age range, 20-88 years) who diagnosed as acute benign (n = 24) and malignant (n = 33) VCFs were finally included for the analysis. The results of all readers showed that the see-through sign was associated with acute benign VCFs (p < 0.05). The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) of the see-through sign ranged from 75-96, 70-88, 66-85, 81-97 %, respectively. The inter-observer reliability of the see-through sign was sufficient with ICC = 0.847, percentage agreement = 78.9, and κ = 0.578.

CONCLUSION

The see-through sign on CE-MRI is featured in acute benign VCFs, and it can be a useful finding to differentiate between benign and malignant VCFs.

The "Hub Disruption Index," a Reliable Index Sensitive to the Brain Networks Reorganization. A Study of the Contralesional Hemisphere in Stroke

Stroke, resulting in focal structural damage, induces changes in brain function at both local and global levels. Following stroke, cerebral networks present structural, and functional reorganization to compensate for the dysfunctioning provoked by the lesion itself and its remote effects. As some recent studies underlined the role of the contralesional hemisphere during recovery, we studied its role in the reorganization of brain function of stroke patients using resting state fMRI and graph theory. We explored this reorganization using the "hub disruption index" (κ), a global index sensitive to the reorganization of nodes within the graph. For a given graph metric, κ of a subject corresponds to the slope of the linear regression model between the mean local network measures of a reference group, and the difference between that reference and the subject under study. In order to translate the use of κ in clinical context, a prerequisite to achieve meaningful results is to investigate the reliability of this index. In a preliminary part, we studied the reliability of κ by computing the intraclass correlation coefficient in a cohort of 100 subjects from the Human Connectome Project. Then, we measured intra-hemispheric κ index in the contralesional hemisphere of 20 subacute stroke patients compared to 20 age-matched healthy controls. Finally, due to the small number of patients, we tested the robustness of our results repeating the experiment 1000 times by bootstrapping on the Human Connectome Project database. Statistical analysis showed a significant reduction of κ for the contralesional hemisphere of right stroke patients compared to healthy controls. Similar results were observed for the right contralesional hemisphere of left stroke patients. We showed that κ, is more reliable than global graph metrics and more sensitive to detect differences between groups of patients as compared to healthy controls. Using new graph metrics as κ allows us to show that stroke induces a network-wide pattern of reorganization in the contralesional hemisphere whatever the side of the lesion. Graph modeling combined with measure of reorganization at the level of large-scale networks can become a useful tool in clinic.

Radiologist variability in assessing the position of the cavoatrial junction on chest radiographs

OBJECTIVE

To assess the variability in identifying the cavoatrial junction (CAJ) on chest X-rays (CXRs) amongst radiologists.

METHODS

23 radiologists (13 consultants and 10 trainees) assessed 25 posteroanterior erect CXRs (including 8 duplicates) and marked the positions of the CAJ. Differences in the CAJ position both within and between observers were evaluated and reported as limits of agreement (LOA), repeatability coefficients (RCs) and intraclass correlation coefficients and were displayed graphically with Bland-Altman plots.

RESULTS

The mean difference for within-observer assessments was -0.2 cm (95% LOA, -1.5 to +1.1 cm) and between observers, it was -0.3 cm (95% LOA, -2.5 to +1.8 cm). Intraobserver RCs were marginally lower for consultants than for trainees (1.1 vs 1.5). RCs between observers were comparable (2.1 vs 2.2) for consultants and trainees, respectively.

CONCLUSION

This study detected a large interobserver variability of the CAJ position (up to 4.3 cm). This is a significant finding considering that the length of the superior vena cava is reported to be approximately 7 cm. We conclude that there is poor consensus regarding the CAJ position amongst radiologists.

ADVANCES IN KNOWLEDGE

No comparisons exist between radiologists in determining CAJ position from CXRs. This report provides evidence of the large observer variability amongst radiologists and adds to the discussion regarding the use of CXRs in validating catheter tip location systems.

Reliability of graph analysis of resting state fMRI using test-retest dataset from the Human Connectome Project

The exploration of brain networks with resting-state fMRI (rs-fMRI) combined with graph theoretical approaches has become popular, with the perspective of finding network graph metrics as biomarkers in the context of clinical studies. A preliminary requirement for such findings is to assess the reliability of the graph based connectivity metrics. In previous test-retest (TRT) studies, this reliability has been explored using intraclass correlation coefficient (ICC) with heterogeneous results. But the issue of sample size has not been addressed. Using the large TRT rs-fMRI dataset from the Human Connectome Project (HCP), we computed ICCs and their corresponding p-values (applying permutation and bootstrap techniques) and varied the number of subjects (from 20 to 100), the scan duration (from 400 to 1200 time points), the cost and the graph metrics, using the Anatomic-Automatic Labelling (AAL) parcellation scheme. We quantified the reliability of the graph metrics computed both at global and regional level depending, at optimal cost, on two key parameters, the sample size and the number of time points or scan duration. In the cost range between 20% to 35%, most of the global graph metrics are reliable with 40 subjects or more with long scan duration (14min 24s). In large samples (for instance, 100 subjects), most global and regional graph metrics are reliable for a minimum scan duration of 7min 14s. Finally, for 40 subjects and long scan duration (14min 24s), the reliable regions are located in the main areas of the default mode network (DMN), the motor and the visual networks.

Usefulness of diffusion-weighted MR imaging for differentiating between benign and malignant superficial soft tissue tumours and tumour-like lesions

OBJECTIVE

To evaluate the usefulness of adding diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping to conventional 3.0-T MRI to differentiate between benign and malignant superficial soft-tissue masses (SSTMs).

METHODS

The institutional review board approved this study and informed consent was waived. The authors retrospectively analyzed conventional MR images including diffusion-weighted images (b-values: 0, 400, 800 s mm(-2)) in 60 histologically proven SSTMs (35 benign and 25 malignant) excluding lipomas. Two radiologists independently evaluated the conventional MRI alone and again with the additional DWI for the evaluation of malignant masses. The mean ADC values measured within an entire mass and the contrast-enhancing solid portion were used for quantitative analysis. Diagnostic performances were compared using receiver-operating characteristic analysis.

RESULTS

For an inexperienced reader, using only conventional MRI, the sensitivity, specificity and accuracy were 84%, 80% and 81.6%, respectively. When combining conventional MRI and DWI, the sensitivity, specificity and accuracy were 96%, 85.7% and 90%, respectively. Additional DWI influenced the improvement of the rate of correct diagnosis by 8.3% (5/60). For an experienced reader, additional DWI revealed the same accuracy of 86.7% without added value on the correct diagnosis. The group mean ADCs of malignant SSTMs were significantly lower than that of benign SSTMs (p < 0.001). The best diagnostic performance with respect to differentiation of SSTMs could be obtained when conventional MRI was assessed in combination with DWI.

CONCLUSION

Adding qualitative and quantitative DWI to conventional MRI can improve the diagnostic performance for the differentiation between benign and malignant SSTMs.

ADVANCES IN KNOWLEDGE

Because the imaging characteristics of many malignant superficial soft-tissue lesions overlap with those of benign ones, inadequate surgical resection due to misinterpretation of MRI often occurs. Adding DWI to conventional MRI yields greater diagnostic performances [area under the receiver-operating characteristic curve (AUC), 0.83-0.99] than does the use of conventional MRI alone (AUC, 0.71-0.93) in the evaluation of malignant superficial masses by inexperienced readers.

Radiographical measurements for distal intra-articular fractures of the radius using plain radiographs and cone beam computed tomography images

OBJECTIVE

Operative treatment of an intra-articular distal radius fracture is one of the most common procedures in orthopedic and hand surgery. The intra- and interobserver agreement of common radiographical measurements of these fractures using cone beam computed tomography (CBCT) and plain radiographs were evaluated.

MATERIALS AND METHODS

Thirty-seven patients undergoing open reduction and volar fixation for a distal radius fracture were studied. Two radiologists analyzed the preoperative radiographs and CBCT images. Agreement of the measurements was subjected to intra-class correlation coefficient and the Bland-Altman analyses.

RESULTS

Plain radiographs provided a slightly poorer level of agreement. For fracture diastasis, excellent intraobserver agreement was achieved for radiographs and good or excellent agreement for CBCT, compared to poor interobserver agreement (ICC 0.334) for radiographs and good interobserver agreement (ICC 0.621) for CBCT images. The Bland-Altman analyses indicated a small mean difference between the measurements but rather large variation using both imaging methods, especially in angular measurements.

CONCLUSIONS

For most of the measurements, radiographs do well, and may be used in clinical practice. Two different measurements by the same reader or by two different readers can lead to different decisions, and therefore a standardization of the measurements is imperative. More detailed analysis of articular surface needs cross-sectional imaging modalities.

T2 relaxation times of the glenohumeral joint at 3.0 T MRI in patients with and without primary and secondary osteoarthritis

BACKGROUND

Quantitative magnetic resonance imaging (MRI) of cartilage has recently been applied to patients with osteoarthritis (OA). T2 mapping is a sensitive method of detecting changes in the chemical composition and structure of cartilage.

PURPOSE

To establish baseline T2 values of glenohumeral joint cartilage at 3.0 T and compare T2 values among subjects with and without OA.

MATERIAL AND METHODS

The study involved 30 patients (18 women, 12 men; median age, 67 years; age range, 51-78 years) with primary (n = 7) and secondary OA (n = 23) in the glenohumeral joint and 34 subjects without OA (19 women, 15 men; median age, 49 years; age range, 23-63 years). All subjects were evaluated by radiography and 3.0 T MRI including a multi-echo T2-weighted spin echo pulse sequence. The T2 value of the cartilage was measured by manually drawing the region of interest on the T2 map. Per-zone comparison of T2 values was performed using Mann-Whitney U test.

RESULTS

Median T2 values differed significantly between subjects without OA (36.00 ms [interquartile range, 33.89-37.31 ms]) and those with primary (37.52 ms [36.84-39.11], P = 0.028), but not secondary (36.87 ms [34.70-41.10], P = 0.160) OA. Glenohumeral cartilage T2 values were higher in different zones between patients with primary and secondary OA than in subjects without OA.

CONCLUSION

These T2 values can be used for comparison to assess cartilage degeneration in patients with shoulder OA. Significant differences in T2 were observed among subjects without OA and those with primary and secondary OA.

Test-retest reliability of graph metrics in high-resolution functional connectomics: a resting-state functional MRI study

BACKGROUND

The combination of resting-state functional MRI (R-fMRI) technique and graph theoretical approaches has emerged as a promising tool for characterizing the topological organization of brain networks, that is, functional connectomics. In particular, the construction and analysis of high-resolution brain connectomics at a voxel scale are important because they do not require prior regional parcellations and provide finer spatial information about brain connectivity. However, the test-retest reliability of voxel-based functional connectomics remains largely unclear.

AIMS

This study tended to investigate both short-term (∼20 min apart) and long-term (6 weeks apart) test-retest (TRT) reliability of graph metrics of voxel-based brain networks.

METHODS

Based on graph theoretical approaches, we analyzed R-fMRI data from 53 young healthy adults who completed two scanning sessions (session 1 included two scans 20 min apart; session 2 included one scan that was performed after an interval of ∼6 weeks).

RESULTS

The high-resolution networks exhibited prominent small-world and modular properties and included functional hubs mainly located at the default-mode, salience, and executive control systems. Further analysis revealed that test-retest reliabilities of network metrics were sensitive to the scanning orders and intervals, with fair to excellent long-term reliability between Scan 1 and Scan 3 and lower reliability involving Scan 2. In the long-term case (Scan 1 and Scan 3), most network metrics were generally test-retest reliable, with the highest reliability in global metrics in the clustering coefficient and in the nodal metrics in nodal degree and efficiency.

CONCLUSION

We showed high test-retest reliability for graph properties in the high-resolution functional connectomics, which provides important guidance for choosing reliable network metrics and analysis strategies in future studies.

Smaller but denser: postmortem changes alter the CT characteristics of subdural hematomas

PURPOSE

The aim of this study was to investigate if (1) the volume of subdural hematomas (SDH), midline shift, and CT density of subdural hematomas are altered by postmortem changes and (2) if these changes are dependent on the postmortem interval (PMI).

MATERIALS AND METHODS

Ante mortem computed tomography (AMCT) of the head was compared to corresponding postmortem CT (PMCT) in 19 adults with SDH. SDH volume, midline shift, and hematoma density were measured on both AMCT and PMCT and their differences assessed using Wilcoxon-Signed Rank Test. Spearman's Rho Test was used to assess significant correlations between the PMI and the alterations of SDH volume, midline shift, and hematoma density.

RESULTS

Mean time between last AMCT and PMCT was 109 h, mean PMI was 35 h. On PMCT mean midline displacement was decreased by 57% (p < 0.001); mean SDH volume was decreased by 38% (p < 0.001); and mean hematoma density was increased by 18% (p < 0.001) in comparison to AMCT. There was no correlation between the PMI and the normalization of the midline shift (p = 0.706), the reduction of SDH volume (p = 0.366), or the increase of hematoma density (p = 0.140).

CONCLUSIONS

This study reveals that normal postmortem changes significantly affect the extent and imaging characteristics of subdural hematoma and may therefore affect the interpretation of these findings on PMCT. Radiologists and forensic pathologists who use PMCT must be aware of these phenomena in order to correctly interpret PMCT findings in cases of subdural hemorrhages.

Diagnostic performance of CT attenuation values of focal 18F-FDG avid breast lesions detected on whole-body PET-CT in postoperative breast cancer patients

To assess whether CT attenuation values help in differentiating benign from malignant etiology of focal (18) F-FDG avid breast lesions detected on whole-body PET/CT exam in postoperative breast cancer patients. Institutional review board approval and waived informed consent were obtained for this HIPAA-compliant retrospective study. Between January 2009 and July 2011, a total of 85 patients had 97 focal (18) F-FDG avid breast lesions on whole-body PET/CT. Of these, 54 (56%) lesions were biopsy-proven primary invasive breast carcinoma that had not undergone treatment at the time of PET/CT, 35 (36%) were benign lesions, and 8 were locally recurrent breast carcinoma. Mean attenuation values were retrospectively measured in Hounsfield units (HU) for the correlative lesion on the CT portion of the exam. Receiver-operating characteristic curves (ROC) were calculated to determine the optimal cutoff values of HU that would best discriminate between benign and malignant lesions. Interobserver agreement for measured mean attenuation values was assessed by calculating the intraclass correlation coefficient (ICC). Mean HU for the benign lesions group and the local recurrence lesions group was -11.0 ± 30.3 versus 32.9 ± 6.87 (p < 0.0002). ROC curve analysis comparing benign breast lesions to local recurrence lesions found an optimal cutoff value of 17 HU (area under curve = 0.982, p < 0.0001, Sensitivity = 100%, Specificity = 89%). ICC with regard to interobserver agreement in measuring the mean HU of the benign lesions was 0.84 (95% confidence interval 0.64-0.93) and for the malignant lesions was 0.88 (95% confidence interval 0.77-0.94). A CT attenuation threshold value of less than 17 HU suggests benign etiology of focal (18) FDG avid breast lesions in postoperative breast cancer patients. If confirmed by additional studies, these findings may provide additional information to guide the treating physician regarding decisions for supplementary imaging or the need to biopsy.

Use of peer assessment in tooth extraction competency

INTRODUCTION

Peer assessment is a widely recognised practice in higher education and is being increasingly utilised in healthcare education. It offers multiple advantages and may play a useful role in enhancing students' learning experience. This study was carried out to evaluate the utility of peer assessment in tooth extraction competency in simulated dental learning environment (SDLE).

METHODS

Year 2 dental students were invited to participate in a formative, peer assessment exercise on forceps tooth extraction in SDLE. The ratings made by peers in the formative assessment were compared with the ratings made by academic supervisors in an equivalent summative assessment.

RESULTS

One hundred and twenty-two students participated in both the formative and summative assessments. Descriptive statistics demonstrated that the majority of students were given the same rating in both assessments. However, there were a number of students who were rated as 'Competent' in one assessment and 'Not Competent' in the other assessment. Spearman's Rho correlations showed that there were weak relationships between the formative and summative assessments. There was also weak inter-rater reliability for the ratings of the peers and academic supervisors, as measured by the intraclass correlation coefficient. Feedback from the students and academic supervisors showed unanimously positive perceptions about the peer assessment experience, and they expressed the desire for incorporating peer assessment in other competencies.

CONCLUSIONS

This study shows mixed results with regard to the value of the peer assessment. Given the potential utility of peer assessment as a tool to augment and enrich students' learning experience, further work needs to be done to evaluate the use of peer assessment in operative competencies in dentistry.

Differentiation of acute osteoporotic and malignant compression fractures of the spine: use of additive qualitative and quantitative axial diffusion-weighted MR imaging to conventional MR imaging at 3.0 T

PURPOSE

To retrospectively determine the value of adding qualitative and quantitative axial diffusion-weighted (DW) imaging to standard spine magnetic resonance (MR) imaging to differentiate between acute osteoporotic and malignant compression fractures at 3.0 T.

MATERIALS AND METHODS

The institutional ethics committee approved this retrospective study and waived the requirement to obtain informed consent. The authors retrospectively analyzed 3.0-T MR images, including DW images (b values: 0, 800, and 1400 sec/mm(2)), in 62 patients with acute compression fractures. Three radiologists independently interpreted MR images for the presence of malignancy by using conventional MR images alone and in combination with axial DW images with qualitative and quantitative analysis. Apparent diffusion coefficients (ADCs) were measured within solid portion with careful use of a small region of interest (ROI). The Mann-Whitney U test was performed.

RESULTS

There were 30 malignant and 32 acute osteoporotic compression fractures. At qualitative analysis, hyperintensity relative to spinal cord was more frequent in malignant compression fractures than in acute osteoporotic compression fractures (87% vs 22%, respectively; P < .001). Median ADCs of malignant fractures were significantly lower than those of benign fractures (P < .001). With conventional MR imaging alone, sensitivity, specificity, and accuracy were 100%, 94%, and 97%, respectively, for reader 1; 97%, 78%, and 87% for reader 2; and 100%, 84%, and 92% for reader 3. With conventional and DW MR imaging combined, sensitivity, specificity, and accuracy were 100%, 97%, and 98% for all three readers. The addition of DW imaging led to correct changes in diagnosis: Reader 1 improved by 1.6% (one of 62 fractures), reader 2 improved by 11% (seven of 62 fractures), and reader 3 improved by 6.5% (four of 62 fractures).

CONCLUSION

The addition of axial DW imaging to a conventional MR imaging protocol improved diagnostic accuracy in the differentiation of acute osteoporotic from malignant compression fractures by measuring ADCs in the solid portion with careful use of a small ROI.

Test-retest reliability of graph metrics in functional brain networks: a resting-state fNIRS study

Recent research has demonstrated the feasibility of combining functional near-infrared spectroscopy (fNIRS) and graph theory approaches to explore the topological attributes of human brain networks. However, the test-retest (TRT) reliability of the application of graph metrics to these networks remains to be elucidated. Here, we used resting-state fNIRS and a graph-theoretical approach to systematically address TRT reliability as it applies to various features of human brain networks, including functional connectivity, global network metrics and regional nodal centrality metrics. Eighteen subjects participated in two resting-state fNIRS scan sessions held ∼20 min apart. Functional brain networks were constructed for each subject by computing temporal correlations on three types of hemoglobin concentration information (HbO, HbR, and HbT). This was followed by a graph-theoretical analysis, and then an intraclass correlation coefficient (ICC) was further applied to quantify the TRT reliability of each network metric. We observed that a large proportion of resting-state functional connections (∼90%) exhibited good reliability (0.6< ICC <0.74). For global and nodal measures, reliability was generally threshold-sensitive and varied among both network metrics and hemoglobin concentration signals. Specifically, the majority of global metrics exhibited fair to excellent reliability, with notably higher ICC values for the clustering coefficient (HbO: 0.76; HbR: 0.78; HbT: 0.53) and global efficiency (HbO: 0.76; HbR: 0.70; HbT: 0.78). Similarly, both nodal degree and efficiency measures also showed fair to excellent reliability across nodes (degree: 0.52∼0.84; efficiency: 0.50∼0.84); reliability was concordant across HbO, HbR and HbT and was significantly higher than that of nodal betweenness (0.28∼0.68). Together, our results suggest that most graph-theoretical network metrics derived from fNIRS are TRT reliable and can be used effectively for brain network research. This study also provides important guidance on the choice of network metrics of interest for future applied research in developmental and clinical neuroscience.

Measurement of steroids in rats after exposure to an endocrine disruptor: mass spectrometry and radioimmunoassay demonstrate similar results

INTRODUCTION

Commercially available radioimmunoassays (RIAs) are frequently used to evaluate the effects of endocrine disrupting chemicals (EDCs) on steroidogenesis in rats. Currently there are limited data comparing steroid concentrations in rats as measured by RIAs to those obtained using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). This study evaluates the concordance of serum and urine steroid concentrations as quantified by select RIA kits and LC-MS/MS following exposure to an EDC, atrazine (ATR).

METHODS

Adult male rats were orally dosed with ATR (200 mg/kg/day) or methylcellulose (1%, vehicle control) for 5 days. Serum was collected and separated into aliquots for analysis. Serum was assayed by RIA for androstenedione (ANDRO), corticosterone (CORT), estradiol (E2), estrone (E1), progesterone (P4), and testosterone (T). Serum was extracted prior to LC-MS/MS analysis with positive electrospray ionization in multiple-reaction monitoring mode for ANDRO, CORT, P4, and T. E1 and E2 concentrations were quantified similarly by LC-MS/MS, following derivatization with dansyl chloride. To compare CORT values from urine, pregnant adult rats were orally dosed with either ATR (100 mg/kg/day) or methylcellulose for 5 days (i.e., gestational days 14-18). Urine samples were collected daily and assayed for CORT by RIA and LC-MS/MS as described above.

RESULTS

Data analyses demonstrated significant agreement between the two detection methods as assessed by Pearson product-moment correlation coefficient, Bland-Altman analysis, and the interclass correlation coefficient. No statistically significant differences were observed between RIA and LC-MS/MS means for any of the steroids assayed.

DISCUSSION

These findings indicate a significant correlation between the measurement of steroids within rat serum and urine using RIA kits and LC-MS/MS. Differences in the absolute measurements existed, but these were not statistically significant. These findings indicate that steroids may be reliably measured in rat biological media using RIAs or LC-MS/MS.

Intra-abdominal hypertension in the critically ill: interrater reliability of bladder pressure measurement

PURPOSE

Intra-abdominal hypertension is frequently underdiagnosed and defined by intra-abdominal pressure (IAP) 12 mm Hg or higher. Increasing IAP may compromise organ viability and culminate in abdominal compartment syndrome. Bladder pressure measurement is a surrogate for IAP, but measurement properties are unknown in the intensive care unit. Our primary objective was to assess the agreement of bladder pressure measurements in critically ill patients.

METHODS

We conducted an observational study examining the correlation of measurement variability of bladder pressure. Four raters (2 nurses and 2 physicians) measured IAP. Patient's age, Acute Physiology and Chronic Health Evaluation II, body mass index, mechanical ventilation parameters, and demographics were collected.

RESULTS

Fifty-one patients had bladder pressures measured in quadruplicate, producing 204 measurements. Among 51 patients, the mean age was 61.9 years, Acute Physiology and Chronic Health Evaluation II was 23.8, and body mass index was 27.8 kg/m2. The average bladder pressure was 12.4 (SD, ±6.2) mm Hg. The interrater agreement by intraclass correlation coefficient was 0.745 (95% confidence interval [CI], 0.637-0.825), 0.804 (95% CI, 0.684-0.882), and 0.626 (95% CI, 0.428-0.767) among all raters, physicians, and nurses, respectively.

CONCLUSIONS

Agreement on bladder pressure was high among 4 clinicians and were not significantly different between physicians and nurses. Given that medical/surgical treatments are considered on bladder pressure values, understanding their reliability is essential to monitor critically ill patients.

A modified Vancouver Scar Scale linked with TBSA (mVSS-TBSA): Inter-rater reliability of an innovative burn scar assessment method

BACKGROUND

Current scar assessment methods do not capture variation in scar outcome across the burn scar surface area. A new method (mVSS-TBSA) using a modified Vancouver Scar Scale (mVSS) linked with %TBSA was devised and inter-rater reliability was assessed.

METHOD

Three raters performed scar assessments on thirty patients with burn scars using the mVSS-TBSA. Scoring on pigmentation, vascularity, pliability and height was undertaken for the 'best' and 'worst' areas of each scar. Raters allocated the total body surface area of the scar (%TBSA) to three mVSS categories (<5, 5-10, >10). Intra-class correlation coefficient (ICC) and weighted kappa statistic (kw) were used to assess inter-rater reliability. The data were also analysed for clinically relevant misclassifications between pairs of raters.

RESULTS

Total mVSS scores showed 'fair to good' agreement (ICC 0.65-0.73) in the 'best' area of the scar while there was 'excellent' agreement in the 'worst' scar area (ICC 0.85-0.88). The kw of the individual mVSS components ranged from 0.44 to 0.84 and 0.02 to 0.86 for 'best' and 'worst' scar areas, respectively. Determination of scar %TBSA had 'excellent' reliability (ICC 0.91-0.96). Allocation of scar %TBSA to severity category <5 mVSS demonstrated 'good to excellent' reliability (ICC 0.63-0.80) and 'fair to good' reliability (ICC 0.42-0.74) for 5-10 mVSS category. However, misclassifications were observed for the total mVSS score in the 'worst' scar area and the allocation of scar %TBSA in the <5 mVSS category.

CONCLUSION

Inter-rater reliability of mVSS scores depends on the severity of the scar area being assessed. The mVSS-TBSA method of allocation of scar %TBSA to two broad mVSS categories, namely <5 and ≥5 mVSS, has 'good to excellent' reliability. The mVSS-TBSA has demonstrated utility for both clinical and research purposes; however, there is potential to misclassify scar outcome in some cases.

Interobserver agreement after pipeline embolization device implantation

BACKGROUND AND PURPOSE

Although flow diversion devices are popular in treatment of aneurysms, angiographic assessment with these devices has rarely been verified by interobserver variability study. The purpose of this study was to determine the interobserver agreement of a 3-point grading system for assessing the angiographic outcome after flow diversion therapy of intracranial, saccular aneurysms and to determine factors affecting such agreement.

MATERIALS AND METHODS

After approval by the institutional review board, 5 independent readers assessed pretreatment and follow-up digital subtraction angiograms from 96 patients treated with the Pipeline embolization device by using a 3-point grading system (complete, near-complete, and incomplete occlusion). "Minor discrepancy" was defined as a difference between any 2 readers of 1 grade, that is, complete vs near-complete or near-complete vs incomplete. "Major discrepancy" was defined as a difference between any 2 readers in which 1 reader noted complete occlusion and the other reader noted incomplete occlusion. We performed statistical analysis for the interobserver agreement by using the intraclass correlation coefficient. Subgroup analyses for discrepancy rate and ICC were performed for previously coiled aneurysms.

RESULTS

The interobserver agreement was excellent (ICC, 0.76; 95% CI, 0.69-0.92). Among 96 cases, there was absolute agreement in 74 (77%), of which 67 had unanimous consensus of "complete" occlusion, 2 "near-complete" occlusion, and 5 "incomplete" occlusion. Discordance between any 2 readers was noted in 22 cases (23%), of which 7 (7.3%) revealed a major discrepancy. Subgroup analysis showed that minor discrepancies were more common among patients previously treated with coils vs those not previously treated with coils (37.5% vs 11.2%; P < .05).

CONCLUSIONS

The observer agreement regarding occlusion after PED therapy is excellent. Only a minority of cases demonstrated discrepancy considered as major in this study.

Age-related differences in test-retest reliability in resting-state brain functional connectivity

Resting-state functional MRI (rs-fMRI) has emerged as a powerful tool for investigating brain functional connectivity (FC). Research in recent years has focused on assessing the reliability of FC across younger subjects within and between scan-sessions. Test-retest reliability in resting-state functional connectivity (RSFC) has not yet been examined in older adults. In this study, we investigated age-related differences in reliability and stability of RSFC across scans. In addition, we examined how global signal regression (GSR) affects RSFC reliability and stability. Three separate resting-state scans from 29 younger adults (18-35 yrs) and 26 older adults (55-85 yrs) were obtained from the International Consortium for Brain Mapping (ICBM) dataset made publically available as part of the 1000 Functional Connectomes project www.nitrc.org/projects/fcon_1000. 92 regions of interest (ROIs) with 5 cubic mm radius, derived from the default, cingulo-opercular, fronto-parietal and sensorimotor networks, were previously defined based on a recent study. Mean time series were extracted from each of the 92 ROIs from each scan and three matrices of z-transformed correlation coefficients were created for each subject, which were then used for evaluation of multi-scan reliability and stability. The young group showed higher reliability of RSFC than the old group with GSR (p-value = 0.028) and without GSR (p-value <0.001). Both groups showed a high degree of multi-scan stability of RSFC and no significant differences were found between groups. By comparing the test-retest reliability of RSFC with and without GSR across scans, we found significantly higher proportion of reliable connections in both groups without GSR, but decreased stability. Our results suggest that aging is associated with reduced reliability of RSFC which itself is highly stable within-subject across scans for both groups, and that GSR reduces the overall reliability but increases the stability in both age groups and could potentially alter group differences of RSFC.

Effects of different correlation metrics and preprocessing factors on small-world brain functional networks: a resting-state functional MRI study

Graph theoretical analysis of brain networks based on resting-state functional MRI (R-fMRI) has attracted a great deal of attention in recent years. These analyses often involve the selection of correlation metrics and specific preprocessing steps. However, the influence of these factors on the topological properties of functional brain networks has not been systematically examined. Here, we investigated the influences of correlation metric choice (Pearson's correlation versus partial correlation), global signal presence (regressed or not) and frequency band selection [slow-5 (0.01–0.027 Hz) versus slow-4 (0.027–0.073 Hz)] on the topological properties of both binary and weighted brain networks derived from them, and we employed test-retest (TRT) analyses for further guidance on how to choose the “best” network modeling strategy from the reliability perspective. Our results show significant differences in global network metrics associated with both correlation metrics and global signals. Analysis of nodal degree revealed differing hub distributions for brain networks derived from Pearson's correlation versus partial correlation. TRT analysis revealed that the reliability of both global and local topological properties are modulated by correlation metrics and the global signal, with the highest reliability observed for Pearson's-correlation-based brain networks without global signal removal (WOGR-PEAR). The nodal reliability exhibited a spatially heterogeneous distribution wherein regions in association and limbic/paralimbic cortices showed moderate TRT reliability in Pearson's-correlation-based brain networks. Moreover, we found that there were significant frequency-related differences in topological properties of WOGR-PEAR networks, and brain networks derived in the 0.027–0.073 Hz band exhibited greater reliability than those in the 0.01–0.027 Hz band. Taken together, our results provide direct evidence regarding the influences of correlation metrics and specific preprocessing choices on both the global and nodal topological properties of functional brain networks. This study also has important implications for how to choose reliable analytical schemes in brain network studies.

New MRI grading system for the cervical canal stenosis

OBJECTIVE

The purpose of this study was to propose a new MRI grading system for cervical canal stenosis and to evaluate the reproducibility of the system.

MATERIALS AND METHODS

Cervical canal stenosis was classified according to the T2-weighted sagittal images into the following grades: grade 0, absence of canal stenosis; grade 1, subarachnoid space obliteration exceeding 50%; grade 2, spinal cord deformity; and grade 3, spinal cord signal change. The MRI scans of 82 patients (37 men and 45 women; mean age, 65.2 years; range, 60-86 years) were independently analyzed by six radiologists. Interobserver and intraobserver agreements were analyzed using intraclass correlation coefficient (ICC), along with the percentage agreement and kappa statistics.

RESULTS

The ICC for interobserver agreement was 0.716-0.802, indicating good-to-excellent agreement. For the distinction among the four grades, the percentage of agreement was 63-64% (κ = 0.60-0.62). The percentage of agreement for the presence of cervical canal stenosis (grade 0 vs grades 1, 2, and 3) was 79-85% (κ = 0.51-0.59). The percentage of agreement for insignificant (grade 0-1) or significant (grade 2-3) stenosis was 81-85% (κ = 0.57-0.66). The percentage of agreement for the presence of spinal cord signal change (grade 0-2 vs grade 3) was 92-95% (κ = 0.70-0.73). The overall intraobserver agreement was excellent, as determined by an ICC of 0.768.

CONCLUSION

The new grading system provides a reliable assessment of cervical canal stenosis.

Graph theoretical analysis of functional brain networks: test-retest evaluation on short- and long-term resting-state functional MRI data

Graph-based computational network analysis has proven a powerful tool to quantitatively characterize functional architectures of the brain. However, the test-retest (TRT) reliability of graph metrics of functional networks has not been systematically examined. Here, we investigated TRT reliability of topological metrics of functional brain networks derived from resting-state functional magnetic resonance imaging data. Specifically, we evaluated both short-term (<1 hour apart) and long-term (>5 months apart) TRT reliability for 12 global and 6 local nodal network metrics. We found that reliability of global network metrics was overall low, threshold-sensitive and dependent on several factors of scanning time interval (TI, long-term>short-term), network membership (NM, networks excluding negative correlations>networks including negative correlations) and network type (NT, binarized networks>weighted networks). The dependence was modulated by another factor of node definition (ND) strategy. The local nodal reliability exhibited large variability across nodal metrics and a spatially heterogeneous distribution. Nodal degree was the most reliable metric and varied the least across the factors above. Hub regions in association and limbic/paralimbic cortices showed moderate TRT reliability. Importantly, nodal reliability was robust to above-mentioned four factors. Simulation analysis revealed that global network metrics were extremely sensitive (but varying degrees) to noise in functional connectivity and weighted networks generated numerically more reliable results in compared with binarized networks. For nodal network metrics, they showed high resistance to noise in functional connectivity and no NT related differences were found in the resistance. These findings provide important implications on how to choose reliable analytical schemes and network metrics of interest.

Mammogram retrieval through machine learning within BI-RADS standards

A content-based mammogram retrieval system can support usual comparisons made on images by physicians, answering similarity queries over images stored in the database. The importance of searching for similar mammograms lies in the fact that physicians usually try to recall similar cases by seeking images that are pathologically similar to a given image. This paper presents a content-based mammogram retrieval system, which employs a query example to search for similar mammograms in the database. In this system the mammographic lesions are interpreted based on their medical characteristics specified in the Breast Imaging Reporting and Data System (BI-RADS) standards. A hierarchical similarity measurement scheme based on a distance weighting function is proposed to model user's perception and maximizes the effectiveness of each feature in a mammographic descriptor. A machine learning approach based on support vector machines and user's relevance feedback is also proposed to analyze the user's information need in order to retrieve target images more accurately. Experimental results demonstrate that the proposed machine learning approach with Radial Basis Function (RBF) kernel function achieves the best performance among all tested ones. Furthermore, the results also show that the proposed learning approach can improve retrieval performance when applied to retrieve mammograms with similar mass and calcification lesions, respectively.

Snakules: a model-based active contour algorithm for the annotation of spicules on mammography

We have developed a novel, model-based active contour algorithm, termed "snakules", for the annotation of spicules on mammography. At each suspect spiculated mass location that has been identified by either a radiologist or a computer-aided detection (CADe) algorithm, we deploy snakules that are converging open-ended active contours also known as snakes. The set of convergent snakules have the ability to deform, grow and adapt to the true spicules in the image, by an attractive process of curve evolution and motion that optimizes the local matching energy. Starting from a natural set of automatically detected candidate points, snakules are deployed in the region around a suspect spiculated mass location. Statistics of prior physical measurements of spiculated masses on mammography are used in the process of detecting the set of candidate points. Observer studies with experienced radiologists to evaluate the performance of snakules demonstrate the potential of the algorithm as an image analysis technique to improve the specificity of CADe algorithms and as a CADe prompting tool.

Evaluation of stylus for radiographic image annotation

We evaluated the use of a stylus as a computer interface for radiographic image annotation. Our case study concerned the annotation of spiculated lesions on mammograms. Three experienced radiologists annotated 20 mammograms depicting spiculated lesions. We evaluated the interobserver agreement in annotations marked with a stylus versus those marked with a mouse using the intraclass correlation coefficient. Better agreement in annotating spicule width was observed with the stylus, suggesting that it is easier to accurately annotate subtle regions on an image using a stylus.

Comparison of algorithms to enhance spicules of spiculated masses on mammography

We have developed an algorithm for enhancement of spicules of spiculated masses, which uses the discrete radon transform. Previously, we employed a commonly used method to compute the discrete radon transform, which we refer to as the DRT. Recently, a new, more exact method to compute the discrete radon transform was developed by Averbuch et al, which is called the fast slant stack (FSS) method. Our hypothesis was that this new formulation would help to improve our enhancement algorithm. To test this idea, we conducted multiple two-alternative-forced-choice observer studies and found that most observers preferred the enhanced images generated with the FSS method.

Intraventricular dyssynchrony in light chain amyloidosis: a new mechanism of systolic dysfunction assessed by 3-dimensional echocardiography

Background

Light chain amyloidosis (AL) is a rare but often fatal disease due to intractable heart failure. Amyloid deposition leads to diastolic dysfunction and often preserved ejection fraction. We hypothesize that AL is associated with regional systolic dyssynchrony. The aim is to compare left ventricular (LV) regional synchrony in AL subjects versus healthy controls using 16-segment dyssynchrony index measured from 3-dimension-al (3D) echocardiography.

Methods

Cardiac 3D echocardiography full volumes were acquired in 10 biopsy-proven AL subjects (60 ± 3 years, 5 females) and 10 healthy controls (52 ± 1 years, 5 females). The LV was subdivided into 16 segments and the time from end-diastole to the minimal systolic volume for each of the 16 segments was expressed as a percent of the cycle length. The standard deviations of these times provided a 16-segment dyssynchrony index (16-SD%). 16-SD% was compared between healthy and AL subjects.

Results

Left ventricular ejection fraction was comparable (control vs. AL: 62.4 ± 0.6 vs. 58.6 ± 2.8%, p = NS). 16-SD% was significantly higher in AL versus healthy subjects (5.93 ± 4.4 vs. 1.67 ± 0.87%, p = 0.003). 16-SD% correlated with left ventricular mass index (R 0.45, p = 0.04) but not to left ventricular ejection fraction.

Conclusion

Light chain amyloidosis is associated with left ventricular regional systolic dyssynchrony. Regional dyssynchrony may be an unrecognized mechanism of heart failure in AL subjects.

A model-based framework for the detection of spiculated masses on mammography

The detection of lesions on mammography is a repetitive and fatiguing task. Thus, computer-aided detection systems have been developed to aid radiologists. The detection accuracy of current systems is much higher for clusters of microcalcifications than for spiculated masses. In this article, the authors present a new model-based framework for the detection of spiculated masses. The authors have invented a new class of linear filters, spiculated lesion filters, for the detection of converging lines or spiculations. These filters are highly specific narrowband filters, which are designed to match the expected structures of spiculated masses. As a part of this algorithm, the authors have also invented a novel technique to enhance spicules on mammograms. This entails filtering in the radon domain. They have also developed models to reduce the false positives due to normal linear structures. A key contribution of this work is that the parameters of the detection algorithm are based on measurements of physical properties of spiculated masses. The results of the detection algorithm are presented in the form of free-response receiver operating characteristic curves on images from the Mammographic Image Analysis Society and Digital Database for Screening Mammography databases.