PROTOCOL FOR ASSESSING THE PRECISION OF PARALYMPIC BOCCIA PLAYERS

ABSTRACT Introduction: Although Paralympic boccia is an up-and-coming sport, demanding more and requiring higher levels of performance from athletes, protocols are not available for evaluating its indicators. Objective: To develop and verify the applicability of a new protocol for assessing the precision of athletes of the sport. Methods: Two targets with two different resolutions (0.5 [RES-0.5] and 1.0 [RES-1.0] points) were developed, graduated from 1 to 7. The protocol consists of placing the targets at 6 locations on the court, and each athlete makes two shots for each target. The best results are considered, from which total precision (TotalP), short precision (SP), medium precision (MP) and long precision (LP) are extracted. Nine players participated in the application of the protocol. The indicators of both targets were compared and verified using the intraclass correlation coefficient (ICC), standard error of measurement (SEm), bias (Bland-Altman) and minimum detectable difference (MDD). Results: Only for LP were there differences between targets (RES-0.5: 9.111 versus RES-1.0: 7.167; p <0.05), while TotalP, SP and MP did not show any significant differences (RES-0.5: 23.11 versus RES-1.0: 25.39; RES-0.5: 18.22 versus RES-1.0: 17.78; RES-0.5: 9.11 versus RES-1.0: 12.44, respectively). In addition, the RES-0.5 target obtained better concordance results (ICC = 0.73; SEm = 3.45; bias = -0.5938; MDD = 8.00), while the RES-1.0 target obtained lower values (CCI = 0.53; SEm = 6.28; bias = 0.3750; MDD = 14.56). Conclusions: The proposed protocol presents excellent applicability results. However, a larger sample of athletes including more details on specific precision indicators should be performed. Level of evidence II; Prospective comparative study.

Quality Enhancement of Gamma Camera SPECT Images Via the Taguchi-Based Optimization of Their Minimum Detectable Difference And a V-Shaped Slit Gauge

Background: This study optimized the minimum detectable difference (MDD) of gamma camera SPECT images via the Taguchi analysis and an indigenous V-shaped slit gauge. The latter was customized to satisfy the Taguchi analysis’ quantitative requirements. Methods: The slit gauge MDD quantification of derived SPECT images was based on a pair of overlapped-peak profiles obtained from a tangent slice of the V-shaped slit with two adjacent peaks. Using the revised Student’s t-test with a multiplied constant, 1.96, the MDD was defined as the minimum distance between two peak centers, which deviation was large enough to ensure a 95% confidence level of their separation. In total, eighteen combinations of six gamma camera scanned factors (A-F), namely (A) collimator, (B) detector to target distance, (C) total counts, (D) acquired energy width, (E) Matrix size, and (F) zoom of collected ROI with each of two or three levels were organized into 18 groups to collect the slit gauge images according to Taguchi L18 orthogonal array. Next, three well-trained radiologists ranked the scanned gauge images to derive the fish-bone-plot of signal-to-noise ratio (S/N, dB) and correlated ANOVA. Results: The quantified MDD was proposed to verify the optimal suggestion of gamma camera scanned protocol, and obtained the MDD as 8.44, 7.88, and 7.40 mm for the 2nd group of the original L18, conventional, and optimal presets, respectively. Conclusions: The optimal preset of gamma camera was achieved according to Taguchi analysis. The MDD-based approach was found more beneficial in evaluating the spatial resolution than the line pair/cm approach in routine quality control in this study.

MINIMUM DETECTABLE DIFFERENCE OF CT ANGIOGRAPHY SCANS AT VARIOUS CARDIAC BEATS: EVALUATION VIA A CUSTOMIZED OBLIQUE V-SHAPED LINE GAUGE AND PMMA PHANTOM

The minimum detectable difference (MDD) at various beats/min (BPM) of CT angiography (CTA) was evaluated using an oblique V-shape line gauge and poly methyl methacrylate (PMMA) phantom in this study. The customized phantom with the size of [Formula: see text][Formula: see text]cm3 was made from a 1[Formula: see text]cm-thick PMMA. The reciprocating mechanism in the phantom was run by a step motor with an eccentric gear connected to a crank rod to provide a stable harmonic motion, simulating the cardiac beats. The MDD has a unique feature in defining the quality characteristic of CT-scanned images and provides more information than simple line pair/cm in the previous studies. The derived MDD was quantified according to various BPM, and the CTA factor combination was preset following either the conventional recommendation or the optimal one. In doing so, the performance was substantiated by the Taguchi-based signal-to-noise ratio and integrated by another index, namely, figure of merit (FOM). The MDD and corresponding [Formula: see text] (dB) changed from [Formula: see text][Formula: see text]mm to [Formula: see text][Formula: see text]mm and from 16.7[Formula: see text]dB to 14.2[Formula: see text]dB, respectively, for conventional settings; while those obtained for the optimal preset changed from [Formula: see text][Formula: see text]mm to [Formula: see text][Formula: see text]mm and from 12.2 dB to 16.4 dB, respectively of CTA at 0–90 BPM. The integrated FOM values for conventional or optimal cases were 1240 and 1337, respectively. The MDD proved to be a useful technique in justifying the CTA-scanned images. For compliance with previous studies, MDD results can be converted to the line pair/cm results, but it is more informative than the quantized number of line pairs.

Leg muscle cross-sectional area measured by ultrasound is highly correlated with MRI

Background The leg muscles are important for balance, posture, and movement during static and dynamic activity. Obtaining cross-sectional area measurements (CSA) of the leg muscles helps researchers understand the health and force production capability of individual leg muscles. Therefore, having an easy to use and readily available method to assess leg muscle CSA is needed. Thus, the purpose of this study was to compare the magnitude, repeatability, and validity of CSA measurements of select leg muscles from ultrasound (US) and the current gold standard, magnetic resonance imaging (MRI). Methods 20 healthy volunteers participated in this study. Each participant was imaged via US and MRI. The muscles of interest obtained on each participant consisted of the tibialis anterior at both 30 and 50% of the shank length, tibialis posterior at both 30 and 50% of the shank length, the flexor digitorum longus, the fibularis (peroneus) longus, and the fibularis (peroneus) brevis. Results Strong Pearson correlations were seen for all of the muscles when comparing US to MRI with a range from .7840 to .9676. For all measurements, standard error of the measurement ranged from .003 to 0.260 cm2. Minimum detectable difference for muscle measurements ranged from .008 cm2 for MRI fibularis longus and fibularis brevis to .693 cm2 for MRI of tibialis anterior at 30%. US minimum detectable difference ranged from .125 cm2 for the tibialis posterior muscle at 30% to .449 cm2 for the tibialis anterior muscle at 50%. Conclusions Based on these results ultrasound is a valid method to obtain CSA of muscles of the leg when compared with MRI.

INTEGRATION OF TAGUCHI ANALYSIS WITH PHANTOM AND INNOVATIVE GAUGES: OPTIMIZATION OF THE CT SCAN PROTOCOL FOR PERIPHERAL ARTERIAL OCCLUSIVE DISEASE (PAOD) SYNDROME

The CT scan protocol optimization for peripheral arterial occlusive disease (PAOD) syndrome was performed by organizing seven CT factors [kVp, mAs, pitch, field of view (FOV) (mm), time of rotation (s), slice thickness (mm), and matrix size] into Taguchi unique [Formula: see text] orthogonal array. The minimum detectable difference (MDD) in the optimizing process was quantified by adopting a customized line group gauge. Besides, three qualified experts in radiology examined by the double-blind criterion the gauge scanned images and ranked them, yielding the optimal setting of CT scan protocols. The latter setting for PAOD included the kVp of 100, mAs of 240, pitch of 0.513, FOV of 320[Formula: see text]mm, rotation time of 0.75[Formula: see text]s, slice thickness of 4.0, and matrix size of [Formula: see text]. The ANOVA and revised Student’s [Formula: see text]-test verified the smallest MDD as 1.43[Formula: see text]mm at a 0.45-mm gauge depth. The ranking process, which makes it possible to magnify and emphasize the imaging correlation among groups, was found to be preferable to grading in the optimization process. The comparative analysis of various MDDs obtained from different medical facilities and literary sources was performed, which revealed that the cardiac X-ray provided the finest spatial resolution according to the quantified MDD. Meanwhile, the CT scan protocol for PAOD adopted in this study had finer MDD than that for the abdomen due to comparatively low kVp or/and mAs.

On the Statistical Testing Methods for Single Laboratory Validation of Qualitative Microbiological Assays with a Paired Design

Background There are several statistical methods for detecting a difference of detection rates between alternative and reference qualitative microbiological assays in a single laboratory validation study with a paired design. Objective We compared performance of eight methods including McNemar’s test, sign test, Wilcoxon signed-rank test, paired t-test, and the regression methods based on conditional logistic (CLOGIT), mixed effects complementary log-log (MCLOGLOG), mixed effects logistic (MLOGIT) models, and a linear mixed effects model (LMM). Methods We first compared the minimum detectable difference in the proportion of detections between the alternative and reference detection methods among these statistical methods for a varied number of test portions. We then compared power and type 1 error rates of these methods using simulated data. Results The MCLOGLOG and MLOGIT models had the lowest minimum detectable difference, followed by the LMM and paired t-test. The MCLOGLOG and MLOGIT models had the highest average power but were anticonservative when correlation between the pairs of outcome values of the alternative and reference methods was high. The LMM and paired t-test had mostly the highest average power when the correlation was low and the second highest average power when the correlation was high. Type 1 error rates of these last two methods approached the nominal value of significance level when the number of test portions was moderately large (n &gt; 20). Highlights The LMM and paired t-test are better choices than other competing methods, and we provide an example using real data.

Bioimpedance Spectroscopy Is a Valid and Reliable Measure of Edema Following Hand Burn Injury (Part 1—Method Validation)

The assessment of swelling following burn injury is complicated by the presence of wounds and dressings and due to patients experiencing significant pain and impaired movement. There remains a lack of sensitive objective measures for edema in patients presenting with hand burn injury. Bioimpedance spectroscopy (BIS) is a measure of body composition that has been demonstrated by our group to be reliable for measuring whole body and limb edema during resuscitation and to be sensitive to edema changes within healing wounds. The aim of this study was to determine the reliability and validity of BIS as a measure of edema following hand burn injury specifically. One hundred patients presenting with burn injury including a portion of a hand were recruited to this trial. Repeated measures of the hand were recorded using a novel application of BIS and in parallel with water displacement volumetry (WDV). The results were analyzed using mixed-effects regressions. Paired repeated measures were obtained for 195 hands, using four electrode configurations. BIS demonstrated high reliability in measuring hand BIS—Intraclass Correlation Coefficient 0.995 to 0.999 (95% CI 0.992–1.000) and sensitivity—Minimum Detectable Difference 0.74 to 3.86 Ω (0.09–0.48 Ω/cm). A strong correlation was shown with WDV, Pearson’s r = −0.831 to −0.798 (P &lt; .001). BIS is a sensitive and reliable measure of edema following acute hand burn injury.

On the Statistical Testing Methods for Single Laboratory Validation of Qualitative Microbiological Assays with an Unpaired Design

Background There exists several statistical methods for detecting a difference of detection rates between alternative and reference qualitative microbiological assays in a single laboratory validation study with an unpaired design. Objective We compared performance of eight methods including Fisher’s exact test, unequal variance two-sample t-test, Wilcoxon rank-sum test, z-test, and methods based on Wilson confidence intervals, complementary log-log regression, Firth’s logistic regression, and ordinary logistic regression. Method We first compared the minimum detectable difference in the proportion of detections between the alternative and reference methods among these statistical methods for a varied number of test portions. We then compared power and size of test of these methods using simulated data. Results Firth’s logistic regression and the unequal variance two-sample t-test had the lowest minimum detectable difference and highest power. None of these statistical methods had an estimated size of test always within a 95% confidence interval of the nominal value 0.05 with small numbers of test portions (n = 12, 20, 30). Fisher’s exact test, the Wilcoxon rank-sum test, and the z-test were conservative even with a moderately large number of test portions (n = 40), while Firth’s logistic regression and the unequal variance two-sample t-test had a size of test closer to 0.05 than other methods. Conclusions Firth's logistic regression and the unequal variance two-sample t-test are better choices than other competing methods. Highlights We recommend the unequal variance two-sample t-test over Firth’s logistic regression because the unequal variance two-sample t-test is better known and easier to use. We provide an example using real data.