Intra-rater Coefficient Of Variation Research Articles

Reliability of MScanFit Motor Unit Number Estimation in the Trapezius Muscle.

MScanFit motor unit number estimation (MUNE) is the most recent MUNE method which has shown promising results in extremity muscles, but it has not been applied to bulbar muscles. Bulbar muscles are particularly important in the diagnosis of amyotrophic lateral sclerosis (ALS). This study aimed to investigate the feasibility and reliability of MScanFit MUNE in the accessory nerve and trapezius muscles. A total of twenty healthy participants were examined twice within 1-2 weeks. We extracted the MScanFit MUNE and size parameter, and compound muscle action potential (CMAP) amplitude values. The reliability of these parameters was assessed using the intra-rater coefficient of variation (CoV), intraclass correlation coefficient (ICC), and Bland-Altman plots. We also correlated MUNE values with CMAP amplitudes using correlation coefficients. Mean MUNE values (Day 1 = 132.1 and Day 2 = 137.4), CMAP amplitudes (Day 1 = 9.71 mV and Day 2 = 10.10 mV) and size parameters did not differ between the two sessions (p > 0.05). CoV showed excellent reliability for MUNE values, size parameters, and CMAP amplitudes (CoV < 7%) whereas ICCs showed moderate reliability for MUNE values (ICC = 0.619), poor to moderate reliability for size parameters (between 0.393 and 0.689), and good reliability for CMAP amplitude (ICC = 0.864) There was no correlation between MUNE values and CMAP amplitudes. MScanFit MUNE is applicable and mostly reliable in the trapezius muscle. Further studies in patients are needed to investigate the sensitivity of MScanFit in this muscle in detecting motor unit loss, particularly in ALS.

O-22 Multiple point stimulation MUNE in ALS: Towards a faster modification

Background Multiple point stimulation (MPS) is a well-established motor unit number estimate (MUNE) method that can be used in all EMG machines, but it is time-consuming. We investigated whether a faster modification of MPS using 5 surface motor unit action potentials (sMUAP) had similar reproducibility, sensitivity and specificity as 10. Material and methods Twenty-two motor neuron disease patients and 20 healthy controls were prospectively examined by two physicians twice in the thenar muscles. Results A total of 168 MPS MUNE recordings were obtained. Mean MUNE was significantly lower in patients in contrast to the controls, whether using 5 [53 ± 55 (1–170) versus 150 ± 64 (51–325), p 0.05) were found between mean MUNE obtained from 5 or 10 sMUAP in both patients and controls. Intra-rater coefficient of variation (CV) for patients (17% versus 15%) and controls (16% versus 13%) and inter-rater CV for patients (25% versus 24%) did not differ between 5 and 10 sMUAP (p > 0.05), whereas inter-rater CV was higher for 5 sMUAP in controls (21% versus 16%, p = 0.004). An excellent intraclass correlation coefficient (⩾0.78) was found, sampling either 5 or 10 sMUAP, for both groups. Receiver operating characteristic (ROC) curves collecting 5 or 10 sMUAP showed excellent accuracy in distinguishing between patients and controls. Conclusions The faster modification of MPS by sampling 5 sMUAP had similar reproducibility, sensitivity and specificity as 10, and may be suggested in future research and clinical practice.

Multiple Point Stimulation MUNE in ALS: Toward a Faster Modification.

Multiple point stimulation is a well-established motor unit number estimate method that can be used in all EMG machines, but it is time-consuming. We investigated whether a faster modification of multiple point stimulation using five surface motor unit action potentials (sMUAP) had similar reproducibility, sensitivity, and specificity as 10. Twenty-two motor neuron disease patients and 20 healthy controls were prospectively examined by two physicians twice in the thenar muscles. A total of 168 multiple point stimulation motor unit number estimate recordings were obtained. Mean motor unit number estimate was significantly lower in patients in contrast to the controls, whether using 5 (53 ± 55 [1-170] vs. 150 ± 64 (51-325), P < 0.001] or 10 sMUAP [52 ± 51 (1-162) vs. 151 ± 50 (75-274), P < 0.001]. No significant differences (P > 0.05) were found between mean motor unit number estimate obtained from 5 or 10 sMUAP in both patients and controls. Intra-rater coefficient of variation (CV) for patients (17% vs. 15%) and controls (16% vs. 13%) and inter-rater coefficient of variation for patients (25% vs. 24%) did not differ between five and 10 sMUAP (P > 0.05), whereas interrater coefficient of variation was higher for five sMUAP in controls (21% vs. 16%, P = 0.004). An excellent intraclass correlation coefficient (≥0.78) was found, sampling either 5 or 10 sMUAP, for both groups. Receiver operating characteristic curves collecting 5 or 10 sMUAP showed excellent accuracy in distinguishing between patients and controls. The faster modification of Multiple point stimulation by sampling five sMUAP had similar reproducibility, sensitivity, and specificity as 10 and may be suggested in future research and clinical practice.

Indirect measurement of the vascular endothelial glycocalyx layer thickness in human submucosal capillaries with a plug-in for ImageJ

BackgroundThe thickness of vascular endothelial glycocalyx layer can be measured indirectly during a spontaneous leukocyte passage from oral submucosal capillaries in humans. The subsequent differences in red blood cell (RBC) column widths, before a spontaneous white blood cell passage (pre-WBC) and after a spontaneous WBC passage (post-WBC) can be used in off-line analysis to measure glycocalyx thickness: [pre-WBC width−post-WBC width]/2. We created and validated a semi-automatic plug-in for ImageJ to measure the endothelial glycocalyx layer thickness. MethodsVideo clips presenting human sublingual microvasculature were created with a side-stream dark field imaging device. Spontaneous leukocyte passages in capillaries were analyzed from video clips with ImageJ. The capillary glycocalyx layer thickness was measured by the indirect approach with two manual and two semi-automatic methods. ResultsThere were no statistically significant differences between glycocalyx layer thicknesses measured with different methods, even though small inter-method differences in RBC column thicknesses could be detected. Inter-rater differences were systematically smaller with both semi-automatic methods. Intra-rater coefficient of variation [CV] (95% CI) was largest when measurements were made completely manually [9.2% (8.4–10.0)], but improved significantly with automatic image enhancement prior to manual measurement [7.2% (6.4–8.0)]. CV could be improved further when using semi-automatic analysis with an in-frame median filter radius of 1 pixel [5.8% (5.0–6.6)], or a median filter radius of 2 pixels [4.3% (3.5–5.1)]. ConclusionsSemi-automatic analysis of glycocalyx decreased the intra-rater CV and the inter-rater differences compared to the manual method. On average, each of the four methods yielded equal results for the glycocalyx thickness. Being the only feasible bed side method in most clinical scenarios, indirect measurement of glycocalyx thickness with orthogonal polarization spectral imaging or side-stream dark field imaging device and our plug-in can advance the study of glycocalyx layer pathology in man.

Frontal parenchymal atrophy measures in multiple sclerosis.

The aim of this study was to establish whether, in a cross-sectional study, the normalized measures of whole and regional brain atrophy correlate better with tests assessing the cognitive function than the absolute brain atrophy measures. The neuropsychological performances and disability have been assessed in 39 patients with relapsing-remitting multiple sclerosis (MS). T1- and T2-lesion load (LL) of total brain and frontal lobes (FLs) were measured using a reproducible semiautomated technique. The whole brain volume and the regional brain parenchymal volume (RBPV) of FLs were obtained using a computerized interactive program, which incorporates semiautomated and automated segmentation processes. Normalized measures of brain atrophy, i.e., brain parenchymal fraction (BPF) and regional brain parenchymal fraction (RBPF) of FLs, were calculated. The scan-rescan, inter- and intrarater coefficient of variation (COV) and intraclass correlation coefficient (ICC) have been estimated. The RBPF of FLs showed an acceptable level of reproducibility which ranged from 1.7% for intrarater variability to 3.2% for scan-rescan variability. The mean ICC was 0.88 (CI 0.82-0.93). The RBPF of FLs demonstrated stronger magnitudes of correlation with neuropsychological functioning, disability and quantitative MRI lesion measures than RBPV. These differences were statistically significant: P<0.001 for Stroop Color Word Interference test, P<0.001 for Paced Auditory Serial Addition Test, P=0.04 for Standard Raven Progressive Matrices, P=0.049 for Expanded Disability Status Scale, P=0.01 for T2-LL of FLs and P<0.001 for T1-LL of FLs. BPF demonstrated significant correlations with tests assessing cognitive functions, whereas BPAV did not. The correlation analysis results were supported by the results of multiple regression analysis which showed that only the normalized brain atrophy measures were associated with tests exploring the cognitive functions. These data suggest that RBPF is a reproducible and sensitive method for measuring frontal parenchymal atrophy. The normalized measures of whole and regional brain parenchymal atrophy should be preferred to absolute measures in future studies that correlate neuropsychological performances and brain atrophy measures in patients with MS.

Apparent diffusion coefficient (ADC) measurements may be more reliable and reproducible than lesion volume on diffusion-weighted images from patients with acute ischaemic stroke–implications for study design

Early ischemic change after stroke can be demonstrated with diffusion-weighted imaging (DWI) and quantified by measuring the apparent diffusion coefficient (ADC) and/or lesion volume. We examined the reliability and reproducibility of lesion volume and ADC measurement on DWI images, and discuss the implications for clinical studies. Using 38 DWI scans from 15 stroke patients, two observers (a physicist and a neuroscience graduate) blind to each other, recorded the lesion volume on DWI sequences, measured the ADC values in this volume and calculated the ratio of ischemic: control ADC (ADCr). One observer repeated his measurements blind to his first, and also examined the effect on lesion volume and ADC of deliberately varying by only one pixel, the outline of the visible boundary of the lesion. The inter and intra-rater reliability were worse for lesion volume than ADC or ADCr measurements: lesion volume, inter-rater coefficient of variation (CoV) 85 ± 130%, intra-rater CoV 20+/−SD80% ( p < 0.05); ADC inter-rater CoV 7.7 ± SD 19%, intra-rater CoV 0.2 ± SD 12% ( p = NS); and ADCr inter-rater CoV 8 ± SD27%, intra-rater CoV 0.8 ± SD73% ( p = NS). Altering the position of the outline tracing of the lesion boundary by one pixel altered the measured volumes by 22 ± SD25% ( p < 0.05), but ADC values were altered by only 2.9 ± SD4.9% and ADCr by 2.7 ± SD4.8% ( p = NS). ADC and ADCr values are more reliable and reproducible than DWI lesion size in acute ischemic stroke because altering where the lesion boundary is measured has a much greater impact on lesion volume than on the ADC or ADCr. This effect is greatest in large lesions.

Tests of functional limitations in fibromyalgia syndrome: a reliability study.

To evaluate the reliability and discriminative ability of a test battery consisting of 7 tests designed for the assessment of functional limitations in patients with fibromyalgia syndrome (FMS). The intrarater reliability of the test battery was evaluated for 15 women with FMS. Interrater reliability was calculated on 4 tests separately. Fifteen healthy women constituted a reference group. The intrarater coefficient of variation was < 8% for the shoulder range of motion tests, chair test, and 6-minute walk test, and < 21% for the shoulder endurance test, with correlation coefficients above 0.80 for all tests. Kappa was 0.70-0.80 for the hand-to-scapula tests. The interrater coefficient of variation was < 5% for shoulder range of motion. The performances of the FMS patients were significantly decreased in comparison with healthy subjects in all the tests except for the hand-to-scapula movement. All but 1 of the selected 7 tests were considered to possess acceptable intrarater reliability for use in FMS in clinical physical therapy practice.

Lesion volume measurement in multiple sclerosis: how important is accurate repositioning?

This study was designed to estimate the contribution of repositioning inaccuracies to measured intracranial lesion volumes in multiple sclerosis (MS). Five patients with MS were each scanned 10 times, using spin-echo imaging (2,000/34/90), contiguous 5-mm slices, and different scanning positions. The maximum displacements from baseline were +/-4 degrees (AP rotation) and 3 mm (slice offset). Lesion volume was measured twice for each scan using a semiautomated contour technique. Measured lesion volumes ranged from 4,328 mm3 to 164,831 mm3. The mean intrarater coefficient of variation (CV) calculated for individual patients ranged from 1.1 to 4% (median, 1.7%). Using analysis of variance, the overall variance and CV due to altered scan position were greater than that due to rater error (repositioning CV 4.0%, intrarater CV 3.5%). The worst-case difference between volumes in the same patient ranged from 8.9 to 32% (median, 9.9%). Both rater and repositioning errors were greater for smaller lesion volumes. The maximum potential error due to repositioning inaccuracies is of a similar magnitude to the 5 to 10% expected change in lesion volume over 1 year. This study justifies continued careful attention to accuracy in repositioning for serial MR studies in patients with MS.