Bland-Altman Limits Of Agreement Research Articles

DXA-derived abdominal fat free mass to predict MRI skeletal muscle mass in postmenopausal women.

Dual-energy X-ray absorptiometry (DXA) is more available than gold-standard magnetic resonance imaging (MRI), but DXA ability to estimate abdominal skeletal muscle mass (SMM) is unknown. DXA-derived abdominal fat-free mass (FFM; Hologic QDR2000 or QDR4500w) was correlated with single-slice MRI SMM at L4 (N = 69; r QDR2000=0.71, QDR4500w=0.69; p<.0001). Linear regression to predict SMM, including DXA FFM, BMI, and age, resulted in an R-squared of 0.72 and 0.65 for QDR2000 and QDR4500. Bland-Altman limits of agreement were ±21g and ±31g for 2-3 standard deviations from the mean difference. DXA predicted abdominal SSM is a moderate proxy for MRI abdominal SMM.

Unilateral Heel-Raise Test: Estimating Normative Value and Reliability in Healthy Teenagers

Abstract Background: The unilateral heel-raise test (UHRT) is a manual muscle testing procedure used to evaluate the power and endurance of the plantar flexors, which are important muscles for human locomotion. UHRT is commonly used in clinical practice, and normative reference values for UHRT in both adults and the pediatric population can be found in the literature. However, there is a lack of normative values for UHRT specifically for teenagers. The objective of this research study was to determine the normative value of UHRT and establish intra-and inter-tester reliability in teenagers in age group 13–17 years old. Materials and Methods: A total of 315 healthy adolescents were recruited as a part of this research. The participants were instructed to stand on the dominant foot by keeping the opposite foot off the ground (by flexing the knee to 90°). UHRT was performed actively up to maximum repetitions until the development of fatigue. Observations were recorded and further analyzed. Results: The inter- and intra-reliability of UHRT were ICC(2,k) = 0.83 (0.77–0.88) and ICC(3,1) = 0.83 (0.76–0.88), respectively. The median value (25th and 75th interquartile range) obtained for UHRT was 21 (18, 24). The Bland-Altman limits of agreement were also satisfied. The standard error of measurement (SEM) was 0.41, and the minimal detectable change (MDC) for the test was estimated to be 2. Conclusions: This study determined the normative values for UHRT in healthy teenagers of the age group 13–17 years old. It provides a valuable benchmark for interpreting the results of UHRT in teenagers. The analyses revealed good inter- and intra-reliability and minimal error, suggesting that it can be used objectively in research and clinical evaluations.

Timed up and go and 30-S chair-stand tests applied via video call are reliable and provide results similar to face-to-face assessment of older adults with different musculoskeletal conditions

BackgroundRemote assessments are promising for coping with adverse situations, such as those imposed by the COVID-19 pandemic. Measurement properties must be specific to the characteristics of the population and the context in which the instruments are used. Purposes: 1) To evaluate the parallel reliability of the timed up and go (TUG) and 30-s chair-stand test (30CST) performed in-person and remotely and 2) to analyze the intra-rater, inter-rater, and test-retest reliability of these tests assessed remotely in older adults with different musculoskeletal conditions. MethodsThe sample included 50 older adults. Parallel reliability was determined by comparing in-person and remote data. Bland-Altman plots displayed differences between tests (TUG and 30CST) performed in-person and remotely, showing the mean scores of each participant. The intra-rater, inter-rater, and test-retest reliability for remote assessments were analyzed using the intraclass correlation coefficient (ICC) with a 95% confidence interval. ResultsParallel reliability was high between in-person and remote assessments (ICC >0.82). Intra-rater, inter-rater, and test-retest reliability were very high for remote assessments (ICC >0.90). The minimal detectable change for the remote assessment of TUG (MDC <1.95) and 30CST (MDC <2.39) indicated adequate sensitivity. In both tests, the standard error of the measurement was acceptable (SEM% < 10%) and Bland-Altman limits of agreement were solid. ConclusionsThe remote assessment of TUG and 30CST in older adults with different musculoskeletal conditions was as reliable as those performed in person and may be considered when in-person assessments are impossible.

Comparison of cystatin C-based estimated glomerular filtration rate with measured glomerular filtration rate in a pediatric cohort of patients with chronic kidney disease.

It is essential to have an accurate assessment of the renal function of patients with chronic kidney disease to monitor, treat, and predict further development of the condition. Measurement of renal function in terms of glomerular filtration rate (GFR) requires either urine or blood sampling, but especially in children, more simple methods of measurement are preferable. The main objective of this study was to examine if the estimated GFR (eGFR) calculated with different cystatin-C-based equations was comparable to the GFR measured by a radiotracer (mGFR) in pediatric patients. In this retrospective study, 28 pediatric patients contributed with 73 pairs of measurements collected within 5 years. Bland-Altman Limits of Agreement were used to evaluate the performance and accuracy of two different cystatin-C-based estimates, the CKiDCrea-CysC and the CKiDU25 respectively, compared to an mGFR based on plasma clearance of technetium-99m-diethylenetriaminepentaacetic acid or chromium-51-ethylenediaminetetraacetic acid. Using the CKiDCrea-CysC equation, 58.9% of the datasets were within P10 and 87.7% were within P30. The mean difference was 4.8 mL/min/1.73m2 (standard deviation: 8.5 mL/min/1.73m2) and tended to overestimate GFR and thereby overrate the kidney function within the entire GFR range. Using the CKiDU25 equation, 53.4% were within P10 and 93.2% within P30. The mean difference was -2.9 mL/min/1.73m2 (standard deviation: 8.4 mL/min/1.73m2), but the difference varied with the GFR value. A cystatin-C-based eGFR provides a viable substitute for monitoring renal function in pediatric patients with chronic kidney disease. However, it has a lower accuracy than mGFR and can therefore not replace mGFR in clinical use.

PCP auto count: a novel Fiji/ImageJ plug-in for automated quantification of planar cell polarity and cell counting.

Introdution: During development, planes of cells give rise to complex tissues and organs. The proper functioning of these tissues is critically dependent on proper inter- and intra-cellular spatial orientation, a feature known as planar cell polarity (PCP). To study the genetic and environmental factors affecting planar cell polarity, investigators must often manually measure cell orientations, which is a time-consuming endeavor. To automate cell counting and planar cell polarity data collection we developed a Fiji/ImageJ plug-in called PCP Auto Count (PCPA). Methods: PCPA analyzes binary images and identifies "chunks" of white pixels that contain "caves" of infiltrated black pixels. For validation, inner ear sensory epithelia including cochleae and utricles from mice were immunostained for βII-spectrin and imaged with a confocal microscope. Images were preprocessed using existing Fiji functionality to enhance contrast, make binary, and reduce noise. An investigator rated PCPA cochlear hair cell angle measurements for accuracy using a one to five agreement scale. For utricle samples, PCPA derived measurements were directly compared against manually derived angle measurements and the concordance correlation coefficient (CCC) and Bland-Altman limits of agreement were calculated. PCPA was also tested against previously published images examining PCP in various tissues and across various species suggesting fairly broad utility. Results: PCPA was able to recognize and count 99.81% of cochlear hair cells, and was able to obtain ideally accurate planar cell polarity measurements for at least 96% of hair cells. When allowing for a <10° deviation from "perfect" measurements, PCPA's accuracy increased to 98%-100% for all users and across all samples. When PCPA's measurements were compared with manual angle measurements for E17.5 utricles there was negligible bias (<0.5°), and a CCC of 0.999. Qualitative examination of example images of Drosophila ommatidia, mouse ependymal cells, and mouse radial progenitors revealed a high level of accuracy for PCPA across a variety of stains, tissue types, and species. Discussion: Altogether, the data suggest that the PCPA plug-in suite is a robust and accurate tool for the automated collection of cell counts and PCP angle measurements.

E072 The psoriatic arthritis disease activity score demonstrates excellent test-retest reliability in early, untreated psoriatic arthritis

Abstract Background/Aims Psoriatic arthritis (PsA) is a chronic inflammatory arthritis characterised by heterogenous clinical features including peripheral arthritis, spondylitis, enthesitis, dactylitis, skin and nail disease. Historically, outcome measures in PsA trials focused on the articular manifestations of disease, with a recent emphasis in composite tools. The Psoriatic Arthritis Disease Activity Score (PASDAS) is a validated, composite measure with defined cut-off and excellent responsiveness when compared with other PsA-specific and non-specific composite measures. Although PASDAS is one of the recommended GRAPPA measures for research trials, data on its test-retest reliability are limited particularly in PsA of short disease duration. Aims and Objectives - To assess the test-retest reliability of the PASDAS composite index in a cohort of early, untreated PsA patients. Methods Data were collected from a subset of participants recruited to the GOLMePsA clinical trial (EudraCT Number: 2013-004122-28), after a minor protocol amendment enabling additional data collection at the screening visit. The test-retest reliability of PASDAS was performed by calculating the intraclass correlation coefficient (ICC) between measurements collected at screening and baseline time-points (maximum 4 weeks apart, by protocol). Table 1 details the sample size calculation. Baseline variables collected in the GOLMePsA trial were described by absolute numbers, percentages, means, medians, absolute and inter-quartile ranges (IQR). Results The PASDAS test-retest reliability was assessed in 37 consecutive participants. Average time between the two time-points was 1.9 weeks (range 0.4 to 4.0). Baseline characteristics of test-retest subset compared to all GOLMePsA participants were similar (table 1). The ICC was 0.85 (95% confidence interval 0.73-0.92). The observed ICC was identical to the value assumed in the sample size calculation for this analysis, yielding an acceptably narrow confidence interval around the estimate. There was no substantial correlation between the means of the two measurements and the differences between them (Pearson’s r=-0.26). The Bland-Altman limits of agreement were -0.11 ± 1.24 (-1.35 to 1.13). Conclusion These results confirm the excellent test-retest reliability of PASDAS in early, untreated PsA, supporting its use as an outcome measure in interventional studies in newly diagnosed disease of short-duration. Disclosure G. De Marco: Consultancies; Janssen, Novartis. E.M.A. Hensor: None. D.G. McGonagle: Consultancies; AbbVie, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, UCB. Grants/research support; AbbVie, BMS, Celgene, Eli Lilly, Janssen, Merck, Novartis, Pfizer, UCB. A. Tan: None. L.C. Coates: Consultancies; AbbVie, Amgen, Bristol Myers Squibb, Celgene, Eli Lilly, Gilead, Galapagos, Janssen, Moonlake, Novartis, Pfizer and UCB. Honoraria; AbbVie, Amgen, Biogen, Celgene, Eli Lilly, Galapagos, Gilead, GSK, Janssen, Medac, Novartis, Pfizer and UCB. Grants/research support; AbbVie, Amgen, Celgene, Eli Lilly, Janssen, Novartis, Pfizer and UCB. P. Emery: None. P.S. Helliwell: None. H. Marzo Ortega: Consultancies; AbbVie, Celgene, Eli-Lilly, Janssen, Moonlake, Novartis, Pfizer, Takeda and UCB. Grants/research support; Janssen, Novartis and UCB.

Validation of a Single-Session Protocol to Determine the Load-Velocity Profile and One-Repetition Maximum for the Back Squat Exercise.

Gomes, M, Fitas, A, Santos, P, Pezarat-Correia, P, and Mendonca, GV. Validation of a single session protocol to determine the load-velocity profile and one-repetition maximum for the back squat exercise. J Strength Cond Res 38(6): 1013-1018, 2024-We investigated whether a single session of absolute incremental loading is valid to obtain the individual load-velocity profile (LVP) and 1 repetition maximum (1RM) for the free-weight parallel back squat. Twenty strength-trained male subjects completed 3 testing sessions, including a baseline 1RM session and 2 LVP sessions (LVP rel based on incremental relative loads and LVP abs based on absolute load increments until 1RM). The 1RM load was compared between the baseline and LVP abs . The load at zero velocity (load-axis intercept [L 0 ]), maximal velocity capacity (velocity-axis intercept [V 0 ]), slope, and area under the load-velocity relationship line (A line ) were compared between the LVP rel and LVP abs using equivalence testing through 2 one-sided t -tests. Measurement accuracy was calculated using the absolute percent error. The 1RM measured at baseline and LVP abs was equivalent and presented a low absolute percent error (1.2%). The following LVP parameters were equivalent between LVP rel and LVP abs : 1RM, L 0 , and A line because the mean difference between sessions was close to zero and the Bland-Altman limits of agreement (1RM:5.3 kg; L 0 :6.8 kg; A line : 9.5 kg·m -1 ·s -1 ) were contained within the a priori defined ± equivalent margins (5% for 1RM and L 0 and 10% for A line ). The aforementioned variables presented a low absolute percent error. However, slope and V 0 were not equivalent between sessions. In conclusion, a single session of absolute incremental loading is a valid approach to obtain the L 0 and A line of the individual LVP and 1RM, and can be used to efficiently track the magnitude of neuromuscular adaptations throughout the training cycles for the free-weight back squat.

Two different autorefractors for vision screening in children and adolescents.

To compare the consistency of two autorefractors (Tianle RM-9000 and Topcon KR-800) for school-age myopia children, and to provide a basis for largescale data analysis and comparison. The refractive error in 909 subjects (age 4-18y) were measured using both autorefractors without cycloplegia. The data were analyzed using Fourier decomposition and the correlation coefficients, intraclass correlation coefficients (ICC), and Bland-Altman limits of agreement (LoA) for each parameter were calculated. There was a strong correlation between the spherical equivalent (SE), sphere diopter (DS), and cylinder diopter (DC) readings of the Tianle RM-9000 and those of the Topcon KR-800, with correlation coefficient values of 0.98, 0.98 and 0.83 and ICC values of 0.99, 0.99 and 0.93, respectively. However, the correlation coefficients and ICC values of J0 and J45 were unreliable (R=-0.004, -0.034; both ICC<0.10). Bland-Altman analysis revealed that SE, DS, and DC measured by the Tianle RM-9000 were significantly biased toward myopia compared with the Topcon KR-800, and the mean differences were -0.072, -0.026, -0.091 D, respectively (all P<0.01). The minimum absolute value of the difference within the 95% LoA for SE, DS, and DC was 0.63 D, 0.50 D, 0.62 D, respectively; all these values were in the clinically acceptable range. For J0 and J45, the mean differences were close to zero (P=0.43, 0.84); however, the 95% LoA were relatively wide (J0 SD: 0.53; 95%CI: -1.00, 1.10; J45 SD: 0.52; 95%CI: -1.00, 1.00). The two autorefractors are consistent with each other, as the differences in SE, DS, and DC were within the clinically acceptable range. Readers can compare the data measured by either device in different studies and use the two devices in the same study to generate a dataset that can be analyzed together. However, the J0 and J45 vectors are unreliable and should not be used to assess astigmatism.

Glomerular filtration rate measurement during platinum treatment for urothelial carcinoma: optimal methods for clinical practice

BackgroundWe assessed the accuracy of four estimated glomerular filtration rate (eGFR) methods: MDRD, Cockcroft–Gault, CKD-EPI, and Wright.MethodThe four methods were compared to measure GFR (mGFR) in patients with urothelial urinary tract cancer (T2-T4bNxMx) receiving platinum-based chemotherapy at Rigshospitalet, Copenhagen, from January 2019 to December 2021. Using standardized assays, creatinine values were measured, and mGFR was determined using Technetium-99 m diethylenetriaminepentaacetic acid (Tc-99 m-DTPA) or Cr-51-ethylenediaminetetraacetic acid (Cr-51-EDTA) plasma clearance. Patients (n = 146) with both mGFR and corresponding creatinine values available were included (n = 345 measurements).ResultsThe CKD-EPI method consistently demonstrated superior accuracy, with the lowest Total Deviation Index of 21.8% at baseline and 22.9% for all measurements compared to Wright (23.4% /24.1%), MDRD (26.2%/25.5%), and Cockcroft–Gault (25.x%/25.1%). Bland Altman Limits of agreement (LOA) ranged from − 32 ml/min (Cockcroft–Gault) to + 33 ml/min (MDRD), with CKD-EPI showing the narrowest LOA (− 27 ml/min to + 24 ml/min and lowest bias (0.3 ml/min). Establishing an eGFR threshold at 85 ml/min—considering both the lower limit of agreement (LOA) and the minimum cisplatin limit at 60 ml/min—allows for the safe omission of mGFR in 30% of patients in this cohort.ConclusionCKD-EPI equation emerged as the most suitable for estimating kidney function in this patient group although not meeting benchmark criteria. We recommend its use for initial assessment and ongoing monitoring, and suggest mGFR for patients with a CKD-EPI estimated GFR below 85 ml/min. This approach could reduce costs and decrease laboratory time for 30% of our UC patients.

Does a self-reported sleep duration reflect actigraphy reported sleep duration in female football players?

ABSTRACT Sleep is often compromised in female athletes, and the monitoring of female athletes' sleep is an important preventative and educational tool. With self-reporting of sleep common practice for athletes as part of a daily wellness assessment, there is a need to understand whether sleep indices are being reported accurately, and thus whether self-report data are useful. This study aimed to compare the agreement between self-reported and actigraphy reported sleep duration in female football players, with the intention of informing best practice for athlete monitoring. Twenty-two female footballers (mean age 19.5 ± 1.3 years) provided a daily self-report across 7 days, whilst also wearing an actigraph across the same testing period. Agreement between the two measures was assessed using Bland-Altman limits of agreement, with acceptable limits of agreement defined as <30 minutes. Results showed evident disagreement between the two methods, with a mean bias of −0.54 (32 min, 95% CI −0.66 to −0.43) and a potential disagreement range of over 2 h (Lower 95% limits of agreement −1.49 to upper 95% limits of agreement 0.40). Coaches using self-reported sleep durations as a monitoring tool for female footballers should interpret the results with caution and be aware of the potential for inaccuracies in this measure. As such, where possible, coaches should consider other methods of sleep monitoring, rather than solely relying on a self-report, to ensure they are operating with optimal practice within situational constraints.

Static palpation ain't easy: Evaluating palpation precision using a topographical map of the lumbar spine as a reference.

Clinicians commonly use manual therapy to treat low back pain by palpating the spine to identify the spinous processes. This study aims to evaluate the ability of experienced clinicians to consistently locate the spinous processes from S1 to T12 through palpation. The results will be compared to topographical data representing the lumbar lordosis at baseline and four follow-up time points. In a prior prospective randomized trial, experienced clinicians used palpation to locate the lumbar spinous processes (S1-T12) and then digitized these locations in three-dimensional space. The same digitizing equipment was then used to continuously collect three-dimensional position data of a wheel that rolled along the back's surface through a trajectory that connected the previously digitized locations of the spinous processes. This process was repeated at 4 days, 1, 4, and 12 weeks. The resulting lordosis trajectories were plotted and aligned using the most anterior point in the lordosis to compare the locations of the spinous processes identified in different trials. This way, spinous palpation points could be compared to surface topography over time. Intra- and interrater reliability and agreement were estimated using intraclass correlations of agreement and Bland-Altman limits of agreement. Five clinicians palpated a total of 119 participants. The results showed a large degree of variation in precision estimates, with a mean total value of 13 mm (95%CI = 11;15). This precision error was consistent across all time points. The smallest precision error was found at L5, followed by S1 File, after which the error increased superiorly. Intra- and interrater reliability was poor to moderate. Comparison of palpation results to a topographic standard representing the lumbar lordosis is a new approach for evaluating palpation. Our results confirm the results of prior studies that find palpation of lumbar spinous processes imprecise, even for experienced clinicians.

Investigation of the Validity and Reliability of Two Smart Bands Selected That Count Steps at Different Walking Speed

Whether activity monitor smart wristbands that have become widespread can accurately estimate the step count while walking is a matter of curiosity. The current study aims to analyze the validity and reliability of step count (SC) estimation at normal walking and fast walking pace under controlled conditions of two selected smart wristbands of the leading wearable device vendors, Xiaomi (Mi4) and Huawei (H4). Twenty healthy adult male and twenty healthy adult female were included in the study and analyzed separately. The mean age of male and female participants was 22.25 and 21.62 years, with BMI values of 24.22 kg/m2 and 21.42 kg/m2, respectively. The above-ground walking protocol consisted of four separate five-minute tests: Normal Walking Test, Normal Walking Retest, Fast Walking Test, and Fast Walking Retest. In the study, the analyses were performed by using activity monitor measurements and criterion measurements (the number of steps determined from video recordings), compatibility of test-retest measurement values, error indicators (MPE and MAPE), Intraclass Correlation Coefficients (ICC), and Bland-Altman limits of agreement. According to the current study results, it was revealed that the MAPE values recorded for Mi4 and H4 smart wristbands for both normal and fast walking pace in male and female participants were &amp;lt;5%, which was deemed excellent. According to all analyses, the H4 device was found to be valid and reliable, but according to ICC and Pearson Correlation analyses, the Mi4 device was not found to be valid and reliable at fast walking pace.

Predicting Leg Forces and Knee Moments Using Inertial Measurement Units: An In Vitro Study.

We compared the ability of seven machine learning algorithms to use wearable inertial measurement unit (IMU) data to identify the severe knee loading cycles known to induce microdamage associated with anterior cruciate ligament rupture. Sixteen cadaveric knee specimens, dissected free of skin and muscle, were mounted in a rig simulating standardized jump landings. One IMU was located above and the other below the knee, the applied three-dimensional action and reaction loads were measured via six-axis load cells, and the three-dimensional knee kinematics were also recorded by a laboratory motion capture system. Machine learning algorithms were used to predict the knee moments and the tibial and femur vertical forces; 13 knees were utilized for training each model, while three were used for testing its accuracy (i.e., normalized root-mean-square error) and reliability (Bland-Altman limits of agreement). The results showed the models predicted force and knee moment values with acceptable levels of error and, although several models exhibited some form of bias, acceptable reliability. Further research will be needed to determine whether these types of models can be modified to attenuate the inevitable in vivo soft tissue motion artifact associated with highly dynamic activities like jump landings.

Reliability of five-minute vs. one-hour heart rate variability metrics in individuals with spinal cord injury.

A previous study showed low reliability of 1-h HRV outcomes in participants with spinal cord injury (SCI), but it was not certain whether the low reliability was due to the unrestricted activity of participants. We aimed to investigate test-retest reliability of HRV metrics in individuals with SCI using a 1-h measurement in a supine position. Individuals with SCI underwent two sessions of 1-h recording of the time between consecutive R waves (RR-intervals) in a supine position. HRV outcomes were obtained from a single 5-min data segment and for the full 1-h recording. HRV parameters of interest were: standard deviation of all normal-to-normal R-R intervals (SDNN) and square root of the mean of the squared differences between successive R-R intervals (RMSSD) (time domain); and high frequency power (HF), low frequency power (LF), very low frequency power (VLF), ultra-low frequency power (ULF) and total power (TP) (frequency domain). Relative reliability was assessed by intraclass correlation coefficient (ICC). Absolute reliability was assessed by coefficient of variation (CV) and Bland-Altman limits of agreement (LoA). Data from 37 individuals (14 with tetraplegia and 23 with paraplegia) were included. Relative reliability was higher for the 1-h (ICCs ranged from 0.13-0.71) than for the 5-min duration (ICCs ranged from 0.06-0.50) in the overall SCI group for all HRV metrics. Participants with tetraplegia had lower relative reliability compared to participants with paraplegia in all HRV metrics for the 5-min duration (ICCs ranged from -0.01-0.34 vs. 0.21-0.57). For the 1-h duration, participants with paraplegia showed higher relative reliability than participants with tetraplegia in all HRV metrics (ICCs ranged from 0.18-0.79 vs. 0.07-0.54) except TP (ICC 0.69 vs. 0.82). In terms of absolute reliability, the CVs and LoAs for the 1-h duration were better than for the 5-min duration. In general, time domain metrics showed better reliability than frequency domain metrics for both durations in participants with tetraplegia and paraplegia. The lowest CV and narrowest 95% LoA were found for SDNN in 5-min and 1-h durations overall and in both lesion levels. The supine position did not provide better reliability compared to unrestricted activity in participants with SCI. HRV analysis using a 5-min duration is of limited value in SCI due to poor reliability. For the 1-h analysis duration, interpretation of the reliability of HRV varies according to lesion level: it is recommended to take lesion level into account when interpreting reliability measures.

Poor Agreement Between Preoperative Transthoracic Echocardiography and Intraoperative Transesophageal Echocardiography for Grading Diastolic Dysfunction

BACKGROUND: Guidelines for the evaluation and grading of diastolic dysfunction are available for transthoracic echocardiography (TTE). Transesophageal echocardiography (TEE) is used for this purpose intraoperatively but the level of agreement between these 2 imaging modalities for grading diastolic dysfunction is unknown. We assessed agreement between awake preoperative TTE and intraoperative TEE for grading diastolic dysfunction. METHODS: In 98 patients undergoing cardiac surgery, key Doppler measurements were obtained using TTE and TEE at the following time points: TTE before anesthesia induction (TTEawake), TTE following anesthesia induction (TTEanesth), and TEE following anesthesia induction (TEEanesth). The primary endpoint was grade of diastolic dysfunction categorized by a simplified algorithm, and measured by TTEawake and TEEanesth, for which the weighted κ statistic assessed observed agreement beyond chance. Secondary endpoints were peak early diastolic lateral mitral annular tissue velocity (e’lat) and the ratio of peak early diastolic mitral inflow velocity (E) to e’lat (E/e’lat), measured by TTEawake and TEEanesth, were compared using Bland-Altman limits of agreement. RESULTS: Disagreement in grading diastolic dysfunction by ≥1 grade occurred in 43 (54%) of 79 patients and by ≥2 grades in 8 (10%) patients with paired measurements for analysis, yielding a weighted κ of 0.35 (95% confidence interval [CI], 0.19–0.51) for the observed level of agreement beyond chance. Bland-Altman analysis of paired data for e’lat and E/e’lat demonstrated a mean difference (95% CI) of 0.51 (−0.06 to 1.09) and 0.70 (0.07–1.34), respectively, for measurements made by TTEawake compared to TEEanesth. The percentage (95% CI) of paired measurements for e’lat and E/e’lat that lay outside the [−2, +2] study-specified boundary of acceptable agreement was 36% (27%–48%) and 39% (29%–51%), respectively. Results were generally robust to sensitivity analyses, including comparing measurements between TTEawake and TTEanesth, between TTEanesth and TEEanesth, and after regrading diastolic dysfunction by the American Society of Echocardiography (ASE)/European Association of CardioVascular Imaging (EACVI) algorithm. CONCLUSIONS: There was poor agreement between TTEawake and TEEanesth for grading diastolic dysfunction by a simplified algorithm, with disagreement by ≥1 grade in 54% and by ≥2 grades in 10% of the evaluable cohort. Future studies, including comparing the prognostic utility of TTEawake and TEEanesth for clinically important adverse outcomes that may be a consequence of diastolic dysfunction, are needed to understand whether this disagreement reflects random variability in Doppler variables, misclassification by the changed technique and physiological conditions of intraoperative TEE, or the accurate detection of a clinically relevant change in diastolic dysfunction.

Peripheral artery disease diagnosis based on deep learning-enabled analysis of non-invasive arterial pulse waveforms

This paper intends to investigate the feasibility of peripheral artery disease (PAD) diagnosis based on the analysis of non-invasive arterial pulse waveforms. We generated realistic synthetic arterial blood pressure (BP) and pulse volume recording (PVR) waveform signals pertaining to PAD present at the abdominal aorta with a wide range of severity levels using a mathematical model that simulates arterial blood circulation and arterial BP-PVR relationships. We developed a deep learning (DL)-enabled algorithm that can diagnose PAD by analyzing brachial and tibial PVR waveforms, and evaluated its efficacy in comparison with the same DL-enabled algorithm based on brachial and tibial arterial BP waveforms as well as the ankle-brachial index (ABI). The results suggested that it is possible to detect PAD based on DL-enabled PVR waveform analysis with adequate accuracy, and its detection efficacy is close to when arterial BP is used (positive and negative predictive values at 40 % abdominal aorta occlusion: 0.78 vs 0.89 and 0.85 vs 0.94; area under the ROC curve (AUC): 0.90 vs 0.97). On the other hand, its efficacy in estimating PAD severity level is not as good as when arterial BP is used (r value: 0.77 vs 0.93; Bland-Altman limits of agreement: −32%-+32 % vs −20%-+19 %). In addition, DL-enabled PVR waveform analysis significantly outperformed ABI in both detection and severity estimation. In sum, the findings from this paper suggest the potential of DL-enabled non-invasive arterial pulse waveform analysis as an affordable and non-invasive means for PAD diagnosis.

Can inertial measurement unit sensors evaluate foot kinematics in drop foot patients using functional electrical stimulation?

The accuracy of inertial measurement units (IMUs) in measuring foot motion in the sagittal plane has been previously compared to motion capture systems for healthy and impaired participants. Studies analyzing the accuracy of IMUs in measuring foot motion in the frontal plane are lacking. Drop foot patients use functional electrical stimulation (FES) to improve walking and reduce the risk of tripping and falling by improving foot dorsiflexion and inversion-eversion. Therefore, this study aims to evaluate if IMUs can estimate foot angles in the frontal and sagittal planes to help understand the effects of FES on drop foot patients in clinical settings. Two Gait Up sensors were used to estimate foot dorsi-plantar flexion and inversion-eversion angles in 13 unimpaired participants and 9 participants affected by drop foot while walking 6 m in a straight line. Unimpaired participants were asked to walk normally at three self-selected speeds and to simulate drop foot. Impaired participants walked with and without FES assistance. Foot angles estimated by the IMUs were compared with those measured from a motion capture system using curve RMSE and Bland Altman limits of agreement. Between participant groups, overall errors of 7.95° ± 3.98°, -1.12° ± 4.20°, and 1.38° ± 5.05° were obtained for the dorsi-plantar flexion range of motion, dorsi-plantar flexion at heel strike, and inversion-eversion at heel strike, respectively. The between-system comparison of their ability to detect dorsi-plantar flexion and inversion-eversion differences associated with FES use on drop foot patients provided limits of agreement too large for IMUs to be able to accurately detect the changes in foot kinematics following FES intervention. To the best of the authors' knowledge, this is the first study to evaluate IMU accuracy in the estimation of foot inversion-eversion and analyze the potential of using IMUs in clinical settings to assess gait for drop foot patients and evaluate the effects of FES. From the results, it can be concluded that IMUs do not currently represent an alternative to motion capture to evaluate foot kinematics in drop foot patients using FES.

Interleaved x-ray imaging: A method for simultaneous acquisition of quantitative and diagnostic digital subtraction angiography.

Flow altering angiographic procedures suffer from ill-defined, qualitative endpoints. Quantitative digital subtraction angiography (qDSA) is an emerging technology that aims to address this issue by providing intra-procedural blood velocity measurements from time-resolved, 2D angiograms. To date, qDSA has used 30 frame/s DSA imaging, which is associated with high radiation dose rate compared to clinical diagnostic DSA (up to 4 frame/s). The purpose of this study is to demonstrate an interleaved x-ray imaging method which decreases the radiation dose rate associated with high frame rate qDSA while simultaneously providing low frame rate diagnostic DSA images, enabling the acquisition of both datasets in a single image sequence with a single injection of contrast agent. Interleaved x-ray imaging combines low radiation dose image frames acquired at a high rate with high radiation dose image frames acquired at a low rate. The feasibility of this approach was evaluated on an x-ray system equipped with research prototype software for x-ray tube control. qDSA blood velocity quantification was evaluated in a flow phantom study for two lower dose interleaving protocols (LD1: and LD2: ) and one conventional (full dose) protocol ( . Dose was measured at the interventional reference point. Fluid velocities ranging from 24 to 45cm/s were investigated. Gold standard velocities were measured using an ultrasound flow probe. Linear regression and Bland-Altman analysis were used to compare ultrasound and qDSA. The LD1 and LD2 interleaved protocols resulted in dose rate reductions of -67.7% and -85.5%, compared to the full dose qDSA scan. For the full dose protocol, the Bland-Altman limits of agreement (LOA) between qDSA and ultrasound velocities were [0.7, 6.7] cm/s with a mean difference of 3.7cm/s. The LD1 interleaved protocol results were similar (LOA: [0.3, 6.9] cm/s, bias: 3.6cm/s). The LD2 interleaved protocol resulted in slightly larger LOA: [-2.5, 5.5] cm/s with a decrease in the bias: 1.5cm/s. Linear regression analysis showed a strong correlation between ultrasound and qDSA derived velocities using the LD1 protocol, with a of , a slope of and an offset of cm/s. Similar values were also found for the LD2 protocol, with a of , a slope of and an offset of cm/s. The interleaved method enables simultaneous acquisition of low-dose high-rate images for intra-procedural blood velocity quantification (qDSA) and high-dose low-rate images for vessel morphology evaluation (diagnostic DSA).

Air Displacement Plethysmography is an Accurate and Feasible Noninvasive Measure of Fat-Free Mass in Children With Intestinal Failure.

The nutritional status of children with intestinal failure (IF) can be difficult to determine using body weight and currently available anthropometric techniques. Air displacement plethysmography (ADP) is a noninvasive measure of whole-body composition that measures body mass and volume, with a calculation of percent body fat (%BF) and fat-free mass (FFM) that may be useful during the provision of specialized nutrition. To evaluate the validity and feasibility of measuring body composition in children with IF using ADP compared with deuterium dilution (DD), as well as secondarily with other measures of body composition, namely bioelectrical impedance analysis (BIA), dual-energy X-ray absorptiometry (DXA), and four-site skinfold anthropometry. We conducted a prospective cohort study of 18 children recruited through the Center for Advanced Intestinal Rehabilitation at Boston Children's Hospital. Patients 2-17 years of age with IF dependent on parenteral nutrition (PN) for more than 90 days were included. Spearman rank correlation and Bland-Altman limits of agreement (LOA) analysis were used to compare ADP to 4 alternative measures of body composition. Eighteen children with IF, median age 7.1 [interquartile range (IQR) 5.4-9.3] years, 9 female (50%), and median residual bowel length 31 (IQR 22-85) cm were enrolled. Median PN energy intake was 46 (IQR 39-49) kcal/kg/day. Incomplete bladder emptying lead to invalid measures of DD in 4 subjects. Spearman correlation coefficients for %BF were low to moderate between ADP and DD ( r = 0.29), DXA ( r = 0.62), BIA ( r = 0.50), and skinfold ( r = 0.40). Correlations for FFM were high between ADP and these other measures (range 0.95-0.98). Comparing ADP with DD and skinfold measures, Bland-Altman analysis showed small mean bias (-1.9 and +1.5 kg) and acceptable 95% LOA ranges (10.7 and 22.9 kg), respectively, with larger bias (-10.7 and -7.7 kg) and LOA ranges (38.7 and 45.2 kg) compared to DXA and BIA. %BF by ADP and skinfold thickness were moderately correlated ( r = 0.43) with low bias (-0.2%) but very wide LOA (25.7%). Body composition via ADP is feasible and valid in children with IF as a measure of FFM but appears less suitable for the measurement of %BF. The technique holds promise as a noninvasive measure of body composition to assess the efficacy of nutritional, medical, and surgical interventions.

Can Wearable Sensors Provide Accurate and Reliable 3D Tibiofemoral Angle Estimates during Dynamic Actions?

The ability to accurately measure tibiofemoral angles during various dynamic activities is of clinical interest. The purpose of this study was to determine if inertial measurement units (IMUs) can provide accurate and reliable angle estimates during dynamic actions. A tuned quaternion conversion (TQC) method tuned to dynamics actions was used to calculate Euler angles based on IMU data, and these calculated angles were compared to a motion capture system (our "gold" standard) and a commercially available sensor fusion algorithm. Nine healthy athletes were instrumented with APDM Opal IMUs and asked to perform nine dynamic actions; five participants were used in training the parameters of the TQC method, with the remaining four being used to test validity. Accuracy was based on the root mean square error (RMSE) and reliability was based on the Bland-Altman limits of agreement (LoA). Improvement across all three orthogonal angles was observed as the TQC method was able to more accurately (lower RMSE) and more reliably (smaller LoA) estimate an angle than the commercially available algorithm. No significant difference was observed between the TQC method and the motion capture system in any of the three angles (p < 0.05). It may be feasible to use this method to track tibiofemoral angles with higher accuracy and reliability than the commercially available sensor fusion algorithm.