Test-retest Repeatability Research Articles

Development, Validity, and Reliability of the Women’s Capabilities Index

We report the results of a series of validity and reliability tests performed during the development of the Women’s Capabilities Index (WCI) in Malawi. The WCI is a multidimensional measure based on Sen’s capability framework for assessing women’s quality of life. Construct validity was assessed by investigating the expected relationships of the dimensions with key socioeconomic characteristics. The majority of hypothesized associations were found to be statistically significant in the expected direction. This provides evidence that the index is measuring quality of life as intended in the conceptual model. Further evidence in support of the index’s validity was given by the high degree of correlation between the WCI and another scale measuring comparable (but not identical) domains of quality of life. The results from the internal consistency and the test–retest repeatability also offered encouraging evidence on the reliability of the instrument. This is the first study to rigorously and comprehensively test for validity and reliability a capabilities index for a low-income setting. The results of the validity and reliability tests provide supportive evidence that a locally developed measure of capabilities can be used as a robust tool for the assessment of women’s quality of life.

Precision of a new ocular biometer in children and comparison with IOLMaster

To assess the repeatability and reproducibility of AL-Scan in agreement with those by the IOLMaster in healthy children, two skilled operators measured ocular parameters in 58 children. The parameters included keratometry (K) values, anterior chamber depth (ACD), axial length (AL), central corneal thickness (CCT), pupil diameter (PD), and corneal diameter (CD). The cohort comprised of 32 boys and 26 girls. The AL-Scan measurements showed high repeatability, as the test-retest repeatability (TRT) values of AL, CCT, ACD, Kf, Ks, Km, CD, and PD were 0.09 mm, 5.1 μm, 0.04 mm, 0.28 D, 0.24 D, 0.21 D, 0.39 mm, and 0.22 mm, respectively. The within-subject coefficient of variation (CoV) was low (<0.35%) and the intraclass correlation coefficients (ICC) of all parameters were >0.85. The interobserver reproducibility was excellent with low values of TRT and ICC > 0.95. The CoV of AL, CCT, ACD, and K was <0.22%. The 95% limits of agreement between the AL-Scan and the IOLMaster were narrow for all parameters except for CD. The repeatability and reproducibility of the new biometer, Al-Scan, was excellent for all parameters and can be routinely used in children to measure the biometric values.

Concurrent validity and reliability of torso-worn inertial measurement unit for jump power and height estimation

ABSTRACTThe purpose of the present study was to evaluate the concurrent validity and test-retest repeatability of torso-worn IMU-derived power and jump height in a counter-movement jump test. Twenty-seven healthy recreationally active males (age, 21.9 [SD 2.0] y, height, 1.76 [0.7] m, mass, 73.7 [10.3] kg) wore an IMU and completed three counter-movement jumps a week apart. A force platform and a 3D motion analysis system were used to concurrently measure the jumps and subsequently derive power and jump height (based on take-off velocity and flight time). The IMU significantly overestimated power (mean difference = 7.3 W/kg; P < 0.001) compared to force-platform-derived power but good correspondence between methods was observed (Intra-class correlation coefficient [ICC] = 0.69). IMU-derived power exhibited good reliability (ICC = 0.67). Velocity-derived jump heights exhibited poorer concurrent validity (ICC = 0.72 to 0.78) and repeatability (ICC = 0.68) than flight-time-derived jump heights, which exhibited excellent validity (ICC = 0.93 to 0.96) and reliability (ICC = 0.91). Since jump height and power are closely related, and flight-time-derived jump height exhibits excellent concurrent validity and reliability, flight-time-derived jump height could provide a more desirable measure compared to power when assessing athletic performance in a counter-movement jump with IMUs.

Development and validation of Image Stimuli for Emotion Elicitation (ISEE): A novel affective pictorial system with test-retest repeatability

The aim of this study was to develop a novel set of pictorial stimuli for emotion elicitation. The Image Stimuli for Emotion Elicitation (ISEE), are the first set of stimuli for which there was an unbiased initial selection method and with images specifically selected for high retest correlation coefficients and high agreement across time. In order to protect against a researcher's subjective bias in screening initial pictures, we crawled 10,696 images from the biggest image hosting website (Flickr.com) based on a computational selection method. In the initial screening study, participants rated stimuli twice for emotion elicitation across a 1-week interval and 1620 images were selected based on the number of ratings of participants and retest reliability of each picture. Using this set of stimuli, a second phase of the study was conducted, again having participants rate images twice with a 1-week interval, in which we found a total of 158 unique images that elicited various levels of emotionality with both good reliability and good agreement over time. The newly developed pictorial stimuli set is expected to facilitate cumulative science on human emotions.

Test-retest reliability of myelin imaging in the human spinal cord: Measurement errors versus region- and aging-induced variations.

PurposeTo implement a statistical framework for assessing the precision of several quantitative MRI metrics sensitive to myelin in the human spinal cord: T1, Magnetization Transfer Ratio (MTR), saturation imposed by an off-resonance pulse (MTsat) and Macromolecular Tissue Volume (MTV).MethodsThirty-three healthy subjects within two age groups (young, elderly) were scanned at 3T. Among them, 16 underwent the protocol twice to assess repeatability. Statistical reliability indexes such as the Minimal Detectable Change (MDC) were compared across metrics quantified within different cervical levels and white matter (WM) sub-regions. The differences between pathways and age groups were quantified and interpreted in context of the test-retest repeatability of the measurements.ResultsThe MDC was respectively 105.7ms, 2.77%, 0.37% and 4.08% for T1, MTR, MTsat and MTV when quantified over all WM, while the standard-deviation across subjects was 70.5ms, 1.34%, 0.20% and 2.44%. Even though particular WM regions did exhibit significant differences, these differences were on the same order as test-retest errors. No significant difference was found between age groups for all metrics.ConclusionWhile T1-based metrics (T1 and MTV) exhibited better reliability than MT-based measurements (MTR and MTsat), the observed differences between subjects or WM regions were comparable to (and often smaller than) the MDC. This makes it difficult to determine if observed changes are due to variations in myelin content, or simply due to measurement error. Measurement error remains a challenge in spinal cord myelin imaging, but this study provides statistical guidelines to standardize the field and make it possible to conduct large-scale multi-center studies.

Fixation parameter test-retest repeatability of the worse eye in central field loss

ObjectivePatients with bilateral central field loss develop peripheral retinal loci (PRLs) in the functional eccentric retina. PRL characteristics and visual performance in the better-seeing eye (BE) of these patients have previously been reported. In this study, we determined the test-retest repeatability of fixation parameters, including fixation stability, PRL eccentricity, and PRL span in the worse-seeing eye (WE). DesignRetrospective consecutive case series. ParticipantsThirty-six patients with bilateral central field loss referred from the Toronto Western Hospital Retina Clinic, who had completed 2 consecutive fixation examinations on the same day. MethodsFixation stability was recorded using the Nidek MP-1 microperimeter (Nidek Technologies Srl., Padova, Italy). For each fixation recording, the following parameters were retrieved: (i) 68.2% bivariate contour ellipse area (BCEA), (ii) PRL span (major and minor axes of the BCEA), (iii) PRL meridian (polar angle), and (iv) PRL eccentricity. Test-retest repeatability for each parameter was assessed using Bland-Altman plots to determine 95% limits of agreement. ResultsThe mean difference between the fixation trial pairs and the 95% limits of agreement for fixation stability, PRL major axis, PRL minor axis, PRL meridian, and PRL eccentricity were 0.06 ± 0.47 log deg2, 0.05° ± 1.42°, 0.07° ± 0.63°, −0.44° ± 66.0°, and −0.23° ±1.56°, respectively. ConclusionsThe fixation parameters in the WE showed robust repeatability, comparable to that of the BE as determined from previous studies. The WE’s fixation repeatability should be considered in the interpretation of fixation outcome measures subsequent to treatment interventions.

Intra-rater repeatability of gait parameters in healthy adults during self-paced treadmill-based virtual reality walking

Self-paced treadmill walking is becoming increasingly popular for the gait assessment and re-education, in both research and clinical settings. Its day-to-day repeatability is yet to be established. This study scrutinised the test-retest repeatability of key gait parameters, obtained from the Gait Real-time Analysis Interactive Lab (GRAIL) system. Twenty-three male able-bodied adults (age: 34.56 ± 5.12 years) completed two separate gait assessments on the GRAIL system, separated by 5 ± 3 days. Key gait kinematic, kinetic, and spatial-temporal parameters were analysed. The Intraclass-Correlation Coefficients (ICC), Standard Error Measurement (SEM), Minimum Detectable Change (MDC), and the 95% limits of agreements were calculated to evaluate the repeatability of these gait parameters. Day-to-day agreements were excellent (ICCs > 0.87) for spatial-temporal parameters with low MDC and SEM values, <0.153 and <0.055, respectively. The repeatability was higher for joint kinetic than kinematic parameters, as reflected in small values of SEM (<0.13 Nm/kg and <3.4°) and MDC (<0.335 Nm/kg and <9.44°). The obtained values of all parameters fell within the 95% limits of agreement. Our findings demonstrate the repeatability of the GRAIL system available in our laboratory. The SEM and MDC values can be used to assist researchers and clinicians to distinguish ‘real’ changes in gait performance over time.

Repeatability of Ophtha Top topography and comparison with IOL-Master and LenstarLS900 in cataract patients.

To determine the repeatability of Ophtha Top topography and assess the consistency with intraocular lens (IOL)-Master and LenstarLS900 (Lenstar) in measuring corneal parameters among cataract patients. Totally 125 eyes were enrolled. Corneas were successively measured with Ophtha Top, IOL-Master and Lenstar at least three times. The flattest meridian power (Kf), the steepest meridian power (Ks), mean power (Km), J0 and J45 were recorded. Intra-class correlation coefficients (ICCs), the coefficient of variance (COV), within subject standard deviation (Sw), and test-retest repeatability (2.77Sw) were adopted to determine the repeatability. The 95% limit of agreement (95%LOA) and Bland-Altman plots were used to assess comparability. Repeatability of Ophtha Top topography for measuring corneal parameters showed the ICCs were all above 0.93, 2.77Sw was lower than 0.31, and the COV of the Kf and Ks was lower than 0.25. The keratometric readings with Ophtha Top topography were flatter than with the IOL-Master and Lenstar devices, while the Pearson correlation coefficients were over 0.97. The J0 and J45 with Ophtha Top topography were smaller compared with Lenstar and IOL-Master, while was comparable between Lenstar and IOL-Master. Ophtha Top topography shows excellent repeatability for measuring corneal parameters. However, differences between the Ophtha TOP topography and Lenstar, IOL-Master both in cornea curvature and the astigmatism should be noted clinically.

Comparison of a new Scheimpflug imaging combined with partial coherence interferometry biometer and a low-coherence reflectometry biometer

To evaluate the repeatability of a new biometer using Scheimpflug technology combined with partial coherence interferometry (PCI) (Pentacam AXL) and its agreement with a device based on optical low-coherence reflectometry (OLCR), the Allegro Biograph. Oftalvist Centro Integral Ocular Jerez, Jerez de la Frontera, Spain. Evaluation of a diagnostic test. The mean keratometry (K), central corneal thickness (CCT), anterior chamber depth (ACD), and axial length (AL) were measured with the 2 devices 3 times by the same examiner in 2 groups (patients with cataract and patients without cataract). The repeatability was determined using the within-subject standard deviation, test-retest repeatability, coefficient of variation, and intraclass correlation coefficient. The correlation was evaluated with the Pearson coefficient and interchangeability with the Bland-Altman plot. Eighty eyes (40 eyes in each group) of 80 patients were analyzed. Significant differences were found between the Scheimpflug-PCI device and the OLCR device for mean K in the normal group (P<.001) and for CCT in the normal group (P<.05) and the cataract group (P<.001). There were no differences between devices in ACD and AL in either group. The repeatability between devices was similar. Although a significant correlation between devices was found for all measurements (all P<.001), wide limits of agreement were found in both groups for all biometric parameters. The Scheimpflug-PCI and OLCR devices showed excellent intravisit repeatability and high correlation for mean K, CCT, ACD, and AL in healthy and cataractous eyes. No differences were found in AL; however, the 2 devices might not be interchangeable.

Pulmonary ventilation imaging in asthma and cystic fibrosis using oxygen-enhanced 3D radial ultrashort echo time MRI.

A previous study demonstrated the feasibility of using 3D radial ultrashort echo time (UTE) oxygen-enhanced MRI (UTE OE-MRI) for functional imaging of healthy human lungs. The repeatability of quantitative measures from UTE OE-MRI needs to be established prior to its application in clinical research. To evaluate repeatability of obstructive patterns in asthma and cystic fibrosis (CF) with UTE OE-MRI with isotropic spatial resolution and full chest coverage. Volunteer and patient repeatability. Eighteen human subjects (five asthma, six CF, and seven normal subjects). Respiratory-gated free-breathing 3D radial UTE (80 μs) sequence at 1.5T. Two 3D radial UTE volumes were acquired sequentially under normoxic and hyperoxic conditions. A subset of subjects underwent repeat acquisitions on either the same day or ≤15 days apart. Asthma and CF subjects also underwent spirometry. A workflow including deformable registration and retrospective lung density correction was used to compute 3D isotropic percent signal enhancement (PSE) maps. Median PSE (MPSE) and ventilation defect percent (VDP) of the lung were measured from the PSE map. The relations between MPSE, VDP, and spirometric measures were assessed using Spearman correlations. The test-retest repeatability was evaluated using Bland-Altman analysis and intraclass correlation coefficients (ICC). Ventilation measures in normal subjects (MPSE = 8.0%, VDP = 3.3%) were significantly different from those in asthma (MPSE = 6.0%, P = 0.042; VDP = 21.7%, P = 0.018) and CF group (MPSE = 4.5%, P = 0.0006; VDP = 27.2%, P = 0.002). MPSE correlated significantly with forced expiratory lung volume in 1 second percent predicted (ρ = 0.72, P = 0.017). The ICC of the test-retest VDP and MPSE were both ≥0.90. In all subject groups, an anterior/posterior gradient was observed with higher MPSE and lower VDP in the posterior compared to anterior regions (P ≤ 0.0021 for all comparisons). 3D radial UTE OE-MRI supports quantitative differentiation of diseased vs. healthy lungs using either whole lung VDP or MPSE with excellent test-retest repeatability. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1287-1297.

Assessing the test–retest repeatability of insulin resistance measures: Homeostasis model assessment 2 and oral glucose insulin sensitivity

Background: Insulin resistance is commonly assessed using the homeostasis model assessment (HOMA) variants. HOMA is potentially insensitive to change because of its high coefficient of variation. The repeatability coefficient is an alternative means of assessing test repeatability. To be confident of clinical change, rather than biological variation, a subsequent test needs to differ from the former by more than the repeatability coefficient using the equation.Test 1 = Test 2 ± repeatability coefficient.The repeatability coefficients for measures of insulin resistance are unknown.Aim: To compare the repeatability coefficient of HOMA2 variants (Beta-cell function [%B], insulin sensitivity [%S], insulin resistance [IR]) to a dynamic measure of insulin resistance, and the oral glucose insulin sensitivity (OGIS) test.Setting: The raw data from a previously used data set were reanalysed.Methods: Glycaemic and insulinaemic tests were performed on 32 men and women both with (n = 10) and without type 2 diabetes (n = 22). From these data, eight fasting tests and three 50-g oral glucose tolerance tests were used to calculate HOMA2 and OGIS. The methods of Bland and Altman assessed repeatability.Results: Repeatability coefficients for all participants for the HOMA2 %B, %S and IR variants were 72.91, 189.75 and 0.9, which equates to 89%, 135% and 89% of their respective grand means. By contrast, OGIS had a repeatability coefficient of 87.13, which equates to 21% of the grand mean.Conclusion: Because of the high repeatability coefficient relative to the grand mean, use of HOMA2 measures for assessing insulin resistance in small population studies should be reconsidered.

Measurement repeatability of the dynamic Scheimpflug analyzer.

To evaluate the repeatability of corneal deformation parameters measured using a dynamic Scheimpflug analyzer and the impact of baseline clinical factors on the repeatability of each parameter. Retrospective, cross-sectional study. Forty-eight eyes (48 healthy subjects; mean age, 49.0±19.5years) underwent repeated examinations with the Scheimpflug analyzer to evaluate the test-retest variability. The intraclass correlation coefficient (ICC) and repeatability coefficient as indicators of variability were computed for 35 parameters measured with the Scheimpflug analyzer. The associations between the magnitude of the test-retest variability and baseline factors, such as age, axial length (AL), intraocular pressure (IOP), and central corneal thickness (CCT), were analyzed. The test-retest repeatability was excellent for 22 (62.9%) of 35 parameters (ICC≥0.75), good for seven (20%), (ICC≥0.6), fair for four (11.4%), (ICC≥0.4), and poor for two (5.7%) parameters (ICC<0.4). Age was associated positively with the magnitude of variability in 13 (37.1%) parameters; measurement variability was affected significantly by AL (5 parameters, 14.3%) and CCT (7 parameters, 20%) but, except for one parameter not by IOP. Most parameters of the dynamic Scheimpflug analyzer showed favorable measurement reliability in healthy subjects. However, six parameters showed poor-to-fair repeatability. Age, AL, and CCT significantly affected the repeatability of several parameters. These results should be considered when clinicians use this device in clinical practice.

Accuracy, repeatability, and interplatform reproducibility of T1 quantification methods used for DCE-MRI: Results from a multicenter phantom study.

To determine the in vitro accuracy, test-retest repeatability, and interplatform reproducibility of T1 quantification protocols used for dynamic contrast-enhanced MRI at 1.5 and 3 T. A T1 phantom with 14 samples was imaged at eight centers with a common inversion-recovery spin-echo (IR-SE) protocol and a variable flip angle (VFA) protocol using seven flip angles, as well as site-specific protocols (VFA with different flip angles, variable repetition time, proton density, and Look-Locker inversion recovery). Factors influencing the accuracy (deviation from reference NMR T1 measurements) and repeatability were assessed using general linear mixed models. Interplatform reproducibility was assessed using coefficients of variation. For the common IR-SE protocol, accuracy (median error across platforms = 1.4-5.5%) was influenced predominantly by T1 sample (P < 10-6 ), whereas test-retest repeatability (median error = 0.2-8.3%) was influenced by the scanner (P < 10-6 ). For the common VFA protocol, accuracy (median error = 5.7-32.2%) was influenced by field strength (P = 0.006), whereas repeatability (median error = 0.7-25.8%) was influenced by the scanner (P < 0.0001). Interplatform reproducibility with the common VFA was lower at 3 T than 1.5 T (P = 0.004), and lower than that of the common IR-SE protocol (coefficient of variation 1.5T: VFA/IR-SE = 11.13%/8.21%, P = 0.028; 3 T: VFA/IR-SE = 22.87%/5.46%, P = 0.001). Among the site-specific protocols, Look-Locker inversion recovery and VFA (2-3 flip angles) protocols showed the best accuracy and repeatability (errors < 15%). The VFA protocols with 2 to 3 flip angles optimized for different applications achieved acceptable balance of extensive spatial coverage, accuracy, and repeatability in T1 quantification (errors < 15%). Further optimization in terms of flip-angle choice for each tissue application, and the use of B1 correction, are needed to improve the robustness of VFA protocols for T1 mapping. Magn Reson Med 79:2564-2575, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Reduced Central Retinal Artery Blood Flow Is Related to Impaired Central Visual Function in Retinitis Pigmentosa Patients

ABSTRACTPurpose: We evaluated the test-retest repeatability of blood flow velocities in the retrobulbar central retinal artery (CRA) and explored whether reduced blood flow is related to the degree of visual function loss in retinitis pigmentosa (RP) patients with wide range of disease severity.Materials and Methods: We measured CRA peak systolic velocity (PSV) and end diastolic velocity (EDV) to calculate mean flow velocity (MFV) in 18 RP patients using color Doppler imaging with spectral flow Doppler (GE Logiq7 ultrasound) twice in each eye at each of two visits within a month. At each of these two visits, we measured ETDRS visual acuity (VA), quick Contrast Sensitivity Function (qCSF), Goldmann visual fields (GVF), 10–2 Humphrey visual fields (HVF), and dark-adaptation at 5° from fixation with the AdaptDx; multifocal electroretinography (mfERG) was obtained at a single visit.Results: Mean coefficients of variation for PSV, EDV and MFV were 16.1–19.2% for within-visit measurements and 20.1–22.4% for between-visit measures. Across patients, greater visual function loss assessed with VA (p = 0.04), extinguished versus measurable amplitude in ring 1 for mfERG (p = 0.001), and cone-only versus rod function with the AdaptDx (p = 0.002) were statistically significantly correlated with reduced MFV in the CRA when included a multilevel multivariate regression model along with the qCSF and HVF results, which all together accounted for 47% of the total variance in MFV. GVF log retinal areas (V4e and III4e; p = 0.30 and p = 0.95, respectively) and measurable far peripheral vision during GVF testing (p = 0.66) were not significantly related to MFV.Conclusions: MFV in the CRA decreased with impaired central vision due to loss of both rod and cone function, had good test-retest repeatability, and may serve as a biomarker outcome to determine the potential physiological basis for improvements in RP clinical trials of therapies with indirect effects on blood flow to the retina.

Assessing Repeatability of Pupillometric Measurements in the Eyes of Refractive Surgery Candidates Using Infrared Pupillometer.

To assess the repeatability of measuring pupil dynamics using an infrared pupillometer. A total of 124 eyes of 124 patients scheduled for corneal laser refractive surgery were separated into myopic and hyperopic groups and further subdivided based on high or low levels of astigmatism. Measurements were taken using dynamic pupillometry (Topolyzer Vario; Alcon Laboratories, Inc., Sinking Spring, PA). Main outcome measures were pupil diameter size, the distance between the pupil center and the keratoscopic axis, and the spatial shift of the pupil center. Repeatability of measurements was assessed from test-retest repeatability (2.77 Sw), coefficient of variation, and intraclass correlation coefficient (ICC). The 2.77 Sw of all measured parameters was lower than 0.36 and 0.44 mm for myopic and hyperopic eyes, respectively. ICCs of the pupil diameter measurements were higher than 0.963 and 0.926 in myopic and hyperopic eyes, respectively. ICCs of the distance between the pupil center and the corneal vertex along the x-axis were higher than 0.934 and 0.994 in myopic and hyperopic eyes, respectively. Along the y-axis, ICCs of this distance were higher than 0.417 in myopic eyes and higher than 0.504 in hyperopic eyes. The pupil center shift measurement ICCs were lower than 0.482 and 0.526 for myopic and hyperopic eyes, respectively. In all groups, the Topolyzer Vario showed excellent repeatability when measuring pupil dynamic parameters except when measuring pupil center shift and distance between the pupil center and the corneal vertex along the vertical axis. [J Refract Surg. 2017;33(8):552-557.].

Repeatability, Reproducibility, and Agreement of Two Scheimpflug-Placido Anterior Corneal Analyzers for Posterior Corneal Surface Measurement.

To evaluate the intraoperator repeatability and interoperator reproducibility of two Scheimpflug-Placido anterior corneal analyzers (Sirius; Costruzione Strumenti Oftalmici, Florence, Italy, and TMS-5; Tomey, Nagoya, Japan) for the measurement of posterior corneal surface in normal eyes and the agreement between the two devices. The current prospective study investigated 55 right eyes of 55 healthy patients in a random order. The posterior steep keratometry (Ks), flat keratometry (Kf), mean keratometry (Km), and astigmatism were randomly measured by two independent experienced operators using the Sirius and TMS-5 Scheimpflug-Placido systems. Three consecutive measurements were obtained. Vector analysis was used for astigmatism. To assess intraoperator repeatability and interoperator reproducibility, within-subject standard deviation (Sw) and test-retest repeatability (TRT, 2.77 Sw) were calculated. The Bland-Altman plots and 95% limits of agreement (LoA) were used to evaluate the agreement between the two systems. In the Sirius Scheimpflug-Placido system, the Sw and TRT of keratometry and astigmatism were less than 0.04 and 0.12 diopters (D), respectively. The interoperator Sw and TRT were less than 0.03 and 0.07 D, respectively. In the TMS-5 Scheimpflug-Placido system, the intraoperator Sw and TRT did not exceed 0.03 and 0.08 D, respectively. The interoperator Sw and TRT were no greater than 0.02 and 0.05 D, respectively. All parameters showed minor fluctuations in the 95% LoA. Both Scheimpflug-Placido systems show high repeatability and reproducibility for posterior corneal surface measurement. A high concordance between the two devices suggests interchangeable use in normal eyes. [J Refract Surg. 2017;33(8):524-530.].

Left ventricular volume measurements with free breathing respiratory self-gated 3-dimensional golden angle radial whole-heart cine imaging – Feasibility and reproducibility

PurposeTo develop and evaluate a free breathing respiratory self-gated isotropic resolution technique for left ventricular (LV) volume measurements. MethodsA 3D radial trajectory with double golden-angle ordering was used for free-running data acquisition during free breathing in 9 healthy volunteers. A respiratory self-gating signal was extracted from the center of k-space and used with the electrocardiogram to bin all data into 3 respiratory and 25 cardiac phases. 3D image volumes were reconstructed and the LV endocardial border was segmented. LV volume measurements and reproducibility from 3D free breathing cine were compared to conventional 2D breath-held cine. ResultsNo difference was found between 3D free breathing cine and 2D breath-held cine with regards to LV ejection fraction, stroke volume, end-systolic volume and end-diastolic volume (P<0.05 for all). The test-retest differences did not differ between 3D free breathing cine and 2D breath-held cine (P<0.05 for all). Conclusion3D free breathing cine and conventional 2D breath-held cine showed similar values and test-retest repeatability for LV volumes in healthy volunteers. 3D free breathing cine enabled retrospective sorting and arbitrary angulation of isotropic data, and could correctly measure LV volumes during free breathing acquisition.

Repeatability of apparent diffusion coefficient and intravoxel incoherent motion parameters at 3.0 Tesla in orbital lesions

ObjectivesTo evaluate repeatability of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) parameters in the orbit.MethodsFrom December 2015 to March 2016, 22 patients were scanned twice using an IVIM sequence with 15b values (0–2,000 s/mm2) at 3.0T. Two readers independently delineated regions of interest in an orbital mass and in different intra-orbital and extra-orbital structures. Short-term test-retest repeatability and inter-observer agreement were assessed using the intra-class correlation coefficient (ICC), the coefficient of variation (CV) and Bland-Altman limits of agreements (BA-LA).ResultsTest-retest repeatability of IVIM parameters in the orbital mass was satisfactory for ADC and D (mean CV 12% and 14%, ICC 95% and 93%), poor for f and D*(means CV 43% and 110%, ICC 90% and 65%). Inter-observer repeatability agreement was almost perfect in the orbital mass for all the IVIM parameters (ICC = 95%, 93%, 94% and 90% for ADC, D, f and D*, respectively).ConclusionsIVIM appeared to be a robust tool to measure D in orbital lesions with good repeatability, but this approach showed a poor repeatability of f and D*.Key Points• IVIM technique is feasible in the orbit.• IVIM has a good–acceptable repeatability of D (CV range 12–25 %).• IVIM interobserver repeatability agreement is excellent (ICC range 90–95 %).• f or D* provide higher test-retest and interobserver variabilities.

The Precision of Hepatic Arterial Infusion Scintigraphy as a Quantitative Biomarker of Tumor Microvasculature.

Optimal clinical development of new cancer therapies targeting tumor vasculature requires new target-specific response assays. This clinical study examined the test-retest repeatability of SPECT as an in vivo assay of angiogenic hepatic tumor microvasculature using an intraarterial infusion of 99mTc-macroaggregated albumin (MAA) delivered via a hepatic artery infusion (HAI) pump. Patients with primary or secondary cancerous liver tumors with HAI pump-catheter implants placed for HAI chemotherapy underwent hepatic SPECT after separate arterial infusions of 37 and 185 MBq of 99mTc-MAA via an HAI pump. Quantitative measures of hepatic tumor MAA uptake were obtained from paired test-retest SPECT datasets. Repeatability was defined by quotients of paired measurands with 95% CIs and coefficients of repeatability (CRs). Test-retest HAI pump SPECT yielded highly repeatable measurements in quantitative indexes of tumor microvasculature. Variability in repeat test-retest measurements was small relative to the range of observed measurements between different tumors. The total hepatic tumor microvascular MAA accumulation (percentage injected dose) proved most repeatable, with test-retest value quotients near unity (quotients: median, 1.10 ± 0.09 [SD]; range, 1.03-1.32; 95% CI, 1.07-1.19) and 1.6% CR. Tumor MAA uptake values ranged from 5% to 18% injected dose. This article describes the precision of HAI SPECT as a quantitative biomarker of tumor microvasculature under conditions of repeatability. The results support clinical testing of HAI SPECT as a radiologic response biomarker for angiotropic tumor therapy.

Test-retest repeatability of human speech biomarkers from static and real-time dynamic magnetic resonance imaging.

Static anatomical and real-time dynamic magnetic resonance imaging (RT-MRI) of the upper airway is a valuable method for studying speech production in research and clinical settings. The test-retest repeatability of quantitative imaging biomarkers is an important parameter, since it limits the effect sizes and intragroup differences that can be studied. Therefore, this study aims to present a framework for determining the test-retest repeatability of quantitative speech biomarkers from static MRI and RT-MRI, and apply the framework to healthy volunteers. Subjects (n = 8, 4 females, 4 males) are imaged in two scans on the same day, including static images and dynamic RT-MRI of speech tasks. The inter-study agreement is quantified using intraclass correlation coefficient (ICC) and mean within-subject standard deviation (σe). Inter-study agreement is strong to very strong for static measures (ICC: min/median/max 0.71/0.89/0.98, σe: 0.90/2.20/6.72 mm), poor to strong for dynamic RT-MRI measures of articulator motion range (ICC: 0.26/0.75/0.90, σe: 1.6/2.5/3.6 mm), and poor to very strong for velocities (ICC: 0.21/0.56/0.93, σe: 2.2/4.4/16.7 cm/s). In conclusion, this study characterizes repeatability of static and dynamic MRI-derived speech biomarkers using state-of-the-art imaging. The introduced framework can be used to guide future development of speech biomarkers. Test-retest MRI data are provided free for research use.