Interstudy Reproducibility Research Articles

Evaluation of the efficacy of oral deferiprone in β‐thalassemia major by multislice multiecho T2*

Oral deferiprone (L1) appears to be promising in the treatment of beta-thalassemia major (TM) patients. T2* magnetic resonance imaging (MRI) with a single measurement in the mid-ventricular septum was validated as a quantitative evaluation of myocardial iron overload. Previous studies suggested a marked heterogeneity of iron distribution in the myocardium. We set up a multislice multiecho T2* MRI for the detection of this heterogeneity. The aim of our study was to investigate differences between the L1 vs. the subcutaneous desferrioxamine (DF)-treated patients using this new approach. Thirty-six beta-TM patients (age 29 +/- 8 yr) underwent MRI. Eighteen patients received long-term L1, and 18 other patients matched for age and sex received DF. T2* multiecho sequences on three short axis views of the left ventricle were obtained and analyzed by custom-made software. In each slice, the myocardium was automatically segmented into four segments. Cine-dynamic images were also obtained to evaluate biventricular function. For multislice T2* technique, the coefficient of variation for intra- and inter-observer, and inter-study reproducibility was 3.9%, 4.7%, and 5.5%, respectively. The global heart T2* value was significantly higher in the L1 vs. DF group (35 +/- 7 vs. 27 +/- 2 ms; P = 0.02). The number of segments with normal T2* value (>20 ms) was significantly higher in the L1 vs. the DF group (11 +/- 1 vs. 8 +/- 5 segments; P = 0.03). We did not detect significant differences in biventricular function parameters. This new approach confirms that L1 could be more effective than DF in removal of myocardial iron.

Inter-Site Validation of a Single Breath Hold T2* MR Technique for Heart and Liver Iron Measurement.

BackgroundApproximately 60,000 people are born with thalassaemia major every year. The average life expectancy of thalassaemia major patients is 35 years due to iron overload Cardiomyopathy. The cardiomyopathy is reversible when treated early, but once heart failure is established it is often rapidly progressive, and unresponsive to treatment. The single breath hold (SBH) T2* technique has been validated as the most robust and reproducible non-invasive measurement of myocardial and iron load. Our aim in this study was to validate the transferability and reproducibility of this technique in different scanners worldwide.MethodsWe aim to compare the reproducibility in six different sites worldwide as part of an NIH funded grant (R01-DK66084-01). So far, two of these sites have been validated: Singapore (Siemens Sonata, 1.5T scanner) and Cagliari, Italy (GE Signa, 1.5 T scanner). At both validation sites, 10 patients were scanned for heart and liver T2*, and scans were repeated for interstudy reproducibility. All patients then flew to London to be rescanned on our reference Siemens Sonata scanner.ResultsOf the 20 patients scanned, 70% had myocardial iron loading (T2* <20ms) and in 10% the myocardial iron loading was severe.Liver iron loading was present in 65% of patients and in 30% this was severe.The coefficient of variation (COV) for the heart T2* measurements between the local sites and London was 5.9% and 4.9% yielding an average coefficient of variation across both sites of 5.4% (figure 1).The coefficient of variation (COV) for the liver T2* measurements between the local sites and London was 11.3% and 3.9% yielding an average coefficient of variation across both sites of 7.6% (figure 2).There was no significant correlation between liver and myocardial loading.ConclusionThese are the first data demonstrating the transferability of the SBH T2* technique and the clinical validation from the 2 collaborating centers were excellent for both heart and liver measurements. Further MR sites confirmed for validation include Children's Hospital of Philadelphia (USA); Ramathibodi Hospital, Bangkok (Thailand); and Chinese University Hong Kong. [Display omitted] [Display omitted]

Techniques necessary for multiple tracer quantitative small-animal imaging studies

Introduction An increasing number and variety of studies on rodent models are being conducted using small-animal positron emission tomography scanners. We aimed to determine if animal handling techniques could be developed to perform routine animal imaging in a timely and efficient manner and with minimal effect on animal physiology. These techniques need to be reproducible in the same animal while maintaining hemodynamic and physiological stability. Methods The necessary techniques include (a) the use of inhalant anesthesia, (b) arterial and venous cannulation for multiple tracer administrations and blood sampling, (c) development of small-volume analytic columns and techniques and (d) measurement of the physiological environment during the imaging session. Results We provide an example of a cardiac imaging study using four radiotracers ( 15O-water, 1-[ 11C]-acetate, 1-[ 11C]-palmitate and 1-[ 11C]-glucose) injected into normal rats. Plasma substrates, CO 2 production and total metabolites were measured. The animals remained anesthetized over the entire imaging session, and their physiological state was maintained. Conclusion The intrastudy stability of the physiological measurements and substrate levels and interstudy reproducibility of the measurements are reported.

Intercentre Reproducibility of Magnetic Resonance T2* Measurements of Myocardial Iron in Thalassaemia

In transfusion-dependent thalassemia major, iron-induced cardiomyopathy is the predominant cause of morbidity and mortality. Assessment of myocardial iron loading using MRI gradient echo T2* measurements have been described, but has only been performed at one centre in London. We assessed the transferability of this method by comparing the results from three different MR scanners in three different countries. Ten patients with thalassemia major underwent myocardial T2* assessment using a Siemens Sonata Scanner in London. Patients were also scanned with either a similar T2* sequence on a GE Systems CVI scanner in Athens, or a GE Systems signa echospeed scanner in Cagliari. Two scans were performed at the respective site in all patients to assess interstudy reproducibility at each site. The mean difference and coefficient of variability for the heart between scanners was 0.08 ms and 9.7% between London and Athens; and 0.30 ms and 1.6% between London and Cagliari. The interstudy mean difference and coefficient of variability for the heart in Athens was 0.6 ms and 3.5%, and 0.2 ms and 2.4% in Cagliari. In conclusion, the myocardial iron estimations were consistent between the three centres with scanners of differing manufacture, suggesting that this technique may have widespread application in the assessment of patients with iron overload conditions such as thalassaemia.

Interstudy Reproducibility of Quantitative Perfusion Cardiovascular Magnetic Resonance

To determine the interstudy reproducibility of quantitative first-pass perfusion cardiovascular magnetic resonance with comparison of 2 previously described analysis techniques. There is no published data on the interstudy reproducibility of perfusion cardiovascular magnetic resonance which can be used to determine the significance of longitudinal changes in myocardial perfusion after pharmacologic or therapeutic interventions with defined sample sizes. Sixteen subjects (7 normal volunteers, 9 patients with coronary artery disease) had rest and adenosine stress perfusion cardiovascular magnetic resonance studies on two separate visits. A short axis slice was studied on each visit using a fast low-angle shot sequence. The global and regional myocardial perfusion reserve indices were calculated using 2 methods: model based constrained deconvolution with the Fermi function, and normalized upslopes. Reproducibility was defined as the standard deviation of the measurement differences, divided by the mean (coefficient of variation). The reproducibility of global myocardial perfusion reserve indices was 21% in normal volunteers, which was similar to that in patients with coronary artery disease (CAD) (23%, p = .88). The reproducibility of regional myocardial perfusion reserve indices was 28% (p = .45 vs. global analysis). The reproducibility of global MPRi was superior with Fermi deconvolution compared with normalized upslopes (21% vs. 41%, p = .02). At this stage of clinical development, the reproducibility of quantitative perfusion cardiovascular magnetic resonance is good, and superior using Fermi deconvolution in preference to upslope analysis.

Interstudy reproducibility of 3D volume selective fast spin echo sequence for quantifying carotid artery wall volume in asymptomatic subjects

Purpose To determine, in asymptomatic subjects, the interstudy reproducibility of a three-dimensional (3D) volume selective fast spin echo (FSE) cardiovascular magnetic resonance sequence for the assessment of carotid artery wall volume as a measure of atheroma burden. Methods Interstudy reproducibility was evaluated in 16 asymptomatic volunteers (10 male, 6 female). Both carotid arteries were scanned twice with a median interscan time of 5 days. The images were acquired in cross-section, and the total carotid arterial wall volume (TWV) was calculated by subtraction of the total carotid lumen volume from the total outer carotid vessel volume. Results The mean carotid T1-weighted TWV for the first and second scans was 828 and 821 mm 3, respectively (mean difference 7 mm 3, p = 0.45). The standard deviation (S.D.) of the differences between the measurements was 38 mm 3 yielding an interstudy coefficient of variation of 4.6%. The time for each study was approximately 30 min. For the longitudinal evaluation of carotid atheroma burden with pharmacological intervention versus placebo, 32 subjects would enable a difference of 38 mm 3 to be detected with a significance level of 5% with 80% power. Conclusion Volumetric analysis with carotid CMR in asymptomatic subjects using a 3D volume-selective FSE is time-efficient with good interstudy reproducibility, and is well suited for longitudinal studies of carotid atheroma with reasonable sample sizes.

Reproducibility of Black-Blood Coronary Vessel Wall MR Imaging

New magnetic resonance imaging (MRI) methods can provide high spatial resolution images of the coronary artery wall, and statistically significant differences in coronary vessel wall thickness between atherosclerotic disease patients and control subjects have been shown. The aim of this study is to assess inter-study reproducibility (i.e., repeatability) of the cross-sectional 2D coronary vessel wall MRI using a black-blood technique. Twelve healthy adult subjects were studied with the use of a commercial 1.5 T CMR system. A double inversion recovery fast spin-echo (FSE) sequence (black blood) was used. Each subject was scanned twice on different days. The mean RCA lumen area difference between study 1 and study 2 was 0.004 mm2, and the coefficient of repeatability (COR) was +/- 0.06 mm2. The mean RCA wall thickness difference between study 1 and study 2 was 0.02 mm, and the COR was +/-0.39 mm. Cross-sectional coronary vessel wall imaging with 2D double-IR FSE is highly reproducible for serial evaluation of coronary vessel walls and atherosclerotic coronary artery disease.

Atrial and Ventricular Volume and Function in Persistent and Permanent Atrial Fibrillation: A Magnetic Resonance Imaging Study

Left atrial size is independently related to cardiovascular morbidity and mortality, and atrial fibrillation (AF) is strongly associated with atrial size. Our aims were to report atrial and ventricular dimensions in patients with AF evaluated with magnetic resonance imaging (MRI), and to assess the inter-study reproducibility of the measurements. Nineteen healthy volunteers, 19 patients with permanent AF, and 58 patients with persistent AF had cardiac dimensions evaluated by 6-mm cinematographic breath-hold MRI scans using a 1.5 Tesla Siemens Vision Magnetom scanner with a phased array chest coil. Intraobserver variability and inter-study reproducibility of the cardiac volumes and ejection fractions (EF) gave acceptable Bland-Altman plots, good correlations (R2: 0.80-0.99), and low reproducibility coefficients. The mean atrial volumes were similar in the two groups with AF [systolic vol. index (SVI): 75.9-80.3 mL/m2; diastolic vol. index (DVI): 77.4-82.1 mL/m2] and significantly different from the healthy volunteers (SVI: 30.3 mL/m2; DVI: 62.3 mL/m2; p < 0.0001). Mean left ventricular (LV) volumes and EF were significantly different in permanent AF (SVI: 34.2 mL/m2; DVI: 68.3 mL/m2; EF: 50.8%) compared to persistent AF [SVI: 44.0 mL/m2 (p = 0.02); DVI: 77.2 mL/m2 (p = 0.03); EF: 44.9% (p = 0.02)], and closer to the normal values (SVI: 22.4 mL/m2; DVI: 66.5 mL/m2; EF: 67.0%). MRI is a highly reproducible method for measurement of atrial and ventricular dimensions in healthy volunteers and in patients with AF. Our results suggest that atrial dilatation appears within the first months of AF and stays more or less unchanged thereafter. The LV appears to dilate early as a response to AF, but later seems to adapt.

Reproducibility of Doppler echocardiographic assessment of left ventricular diastolic function in multicenter setting

Whether Doppler echocardiography allows reliable assessment of left ventricular (LV) diastolic parameters in multicenter studies is disputed. To assess interstudy reproducibility of Doppler echocardiographic parameters of LV filling and relaxation in multicenter setting, two laboratories assessed Doppler parameters of LV filling and relaxation twice within 24 hours in 56 participants. The study sample included hospitalized patients, clinically healthy outpatients, and healthy volunteers. All studies were performed according to a standardized protocol, and read by a single reader. In the whole study sample the reproducibility of the assessment of the ratio between the peak velocities of the early (E) and late (A) LV filling waves (E/A), of the E wave deceleration time and atrial filling fraction, measured at the mitral valve leaflet tips, was good (intraclass correlation coefficients, rho: 0.89-0.76); the reproducibility performance of the same parameters measured at the mitral anulus was less good. The reproducibility of the assessment of the isovolumic relaxation time was good (rho: 0.81), and that of the E-wave propagation rate (E-Vp), by color M-mode, was excellent (rho: 0.96). The reproducibility of the ratio E wave peak velocity/E-Vp was also fairly good (rho: 0.87). The classification of E-Vp < 45 cm/s and E-Vp > or = 55 cm/s showed the highest between-study reliability performance (agreement index kappa = 0.92 and 0.83, respectively, both P < .001), followed by E/A at mitral leaflet tips >1.5 or <0.8 (kappa = 0.78 and 0.74, respectively, both P < .01), whereas the worst reliability performance was shown by isovolumic relaxation time < 60 milliseconds (kappa = 0.05, P = not significant). Standardized procedures for imaging and readings allowed good reliability of serial Doppler echocardiographic evaluations of LV filling and relaxation parameters in multicenter setting.

Interstudy reproducibility of three‐dimensional volume‐selective fast spin echo magnetic resonance for quantifying carotid artery wall volume

To assess the interstudy reproducibility of a three-dimensional volume-selective, fast spin echo (FSE) magnetic resonance technique for the assessment of carotid artery wall volume, which is a marker for total carotid plaque volume. Interstudy reproducibility was evaluated in 10 subjects with evidence of carotid artery atherosclerotic disease on carotid Doppler ultrasonography. Subjects were scanned twice with an interscan time of one hour to four days. The carotid artery was imaged in cross-section, and the total carotid arterial wall volume (TWV) was calculated by subtraction of the total carotid lumen volume from the total outer carotid vessel volume. The mean carotid TWV for the scans was 741 and 734 mm3, respectively, with no significant difference (mean difference 7 mm3; P = 0.5). The time for each study was approximately 20 minutes. The standard deviation of the differences between the measurements was 33 mm3, yielding an interstudy coefficient of variation of 4.4%. Sample size calculations showed that 16 patients would enable this difference in plaque volume over time to be detected with 80% power at a P value of 0.05. Volumetric analysis with CMR of carotid artery plaques using a three-dimensional volume-selective FSE is efficient with good interstudy reproducibility, and is well suited for longitudinal studies of progression of carotid atheroma with reasonable sample sizes.

Routine breath-hold gradient echo MRI-derived right ventricular mass, volumes and function: accuracy, reproducibility and coherence study

Right ventricular (RV) dysfunction is a predictor of poor outcome in patients with heart disease. Conventional imaging modalities fail to assess RV volumes accurately. We sought to assess the accuracy and reproducibility of routine breath-hold gradient echo magnetic resonance imaging (MRI)-derived RV mass, volumes and function. We assessed: (1) The accuracy of in vivo MRI-derived RV mass in comparison to the RV weight in 9 minipigs. (2) Intra- and inter-observer reproducibility of RV mass, end-diastolic (EDV) and end-systolic (ESV) volumes and ejection fraction (EF) in 15 normal volunteers and 10 patients with heart disease. (3) Inter-study reproducibility of the former parameters in 25 coronary artery disease patients. (4) The correlation between right and left ventricular stroke volumes in the total population. Strong statistically significant correlations were found between: (1) MRI-derived RV mass and RV weight (r = 0.98, bias = 2.5 g), (2) Intra-observer measurements of RV mass (r = 0.96, bias = 0.5 g), EDV (r = 0.99, bias = -1.5 ml), ESV (r = 0.98, bias = 0.1 ml) and EF (r = 0.92, bias = -1.4%), (3) Inter-observer measurements of RV mass (r = 0.95, bias = 1.1 g), EDV (r = 0.98, bias = -1.1 ml), ESV (r = 0.98, bias = 1.2 ml) and EF (r = 0.87, bias = -1.9%), (4) Inter-study measurements of RV mass (r = 0.91, bias = -0.1 g), EDV (r = 0.96, bias = 3.8 ml), ESV (r = 0.98, bias = 0.3 ml) and EF (r = 0.90, bias = 0.9%), (5) MRI-derived right and left ventricular stroke volumes (r = 0.87). The assessment of the RV mass, volumes and function by routine breath-hold gradient echo MRI is accurate and highly reproducible. The correlation between left and RV MRI-derived stroke volumes indicates excellent coherence of simultaneous bi-ventricular volume measurements.

Inter- and intra-study reproducibility of contrast echocardiography for assessment of interventricular septal wall perfusion rate in humans.

To assess inter- and intra-study reproducibility of myocardial contrast echocardiography (MCE) imaging for quantitative measurement of myocardial perfusion rate in humans in ambulatory setting. In 20 subjects, we performed 2 MCE tests 20-40 min apart on the same day under the same standardized protocol, and evaluated single-reader between-study and between-reading reproducibility of assessment of indicators of myocardial perfusion rate, such as the slope of video-intensity change k, and the factors A (peak video-intensity) and B (background video-intensity after bubble destruction) and the product k X A. The region of interest was placed at the mid-posterior interventricular septal wall visualized in apical 4-chamber view. In a sub-analysis, we evaluated indicators of myocardial perfusion rate comparing subjects with normal vs. those with subnormal ejection fraction (EF). Inter-study reproducibility of assessment of k was relatively low (intraclass correlation coefficient = 0.36), whereas intra-study reproducibility was fair (intraclass correlation coefficient = 0.61). The parameters k X A and B showed higher reproducibility than the k (inter- and intra-study intraclass correlation coefficients 0.64 and 0.75, 0.74 and 0.91, respectively). For reference, reproducibility data of the depth of the region of interest, of EF and CO were excellent. k and k X A were lower in subjects with low vs. those with normal EF. Only k and k X A were lower in subjects with subnormal than in those with normal EF. The MCE-derived indicator of myocardial perfusion rate k X A showed fairly good between-study and between-reading reproducibility.

Cardiovascular magnetic resonance and the role of adenosine pharmacologic stress

As an advanced imaging modality, cardiovascular magnetic resonance (CMR) offers high spatial resolution and produces unsurpassed images of the heart and its function. Clinically, CMR is well established in the assessment of congenital heart disease, the aorta, tumors, the pericardium, cardiac mass and function, flow measurement, and the structure and function of the right ventricle. CMR has demonstrated a high interstudy reproducibility of left ventricular volumes, ejection fraction, and mass, making it the ideal noninvasive technique for serial measurements. CMR growth areas that are nearing routine clinical application are the evaluation of myocardial perfusion, infarction, and viability. In perfusion CMR studies, pharmacologic stress is used to increase differences in the first-pass delivery of the contrast agent between myocardial regions perfused by normal and diseased arteries. The most widely used stress modality for CMR perfusion studies is adenosine.

Intra- and interstudy reproducibility of coronary artery diameter measurements in magnetic resonance coronary angiography.

To determine the intra- and interstudy reproducibility of right coronary artery diameter assessment using serial magnetic resonance (MR) coronary angiography. Two-dimensional (2D) navigator-gated segmented fast low angle shot (FLASH) images of the proximal right coronary artery were acquired three times in 11 healthy volunteers, the first two times in the same study session and the third time after repositioning the subject in the scanner. Coronary artery diameters were determined using automated segmentation software and intra- and interstudy reproducibility calculated as the standard deviation (SD) of the signed differences between measurements within and between study sessions, respectively. The reproducibility of the segmentation software was determined by repeated analysis of each individual scan. One subject was excluded from the study due to poor-quality images. In the remaining 10 subjects, the mean (+/- SD) intrastudy difference in coronary artery diameters was -0.05 +/- 0.12 mm, a value that is very similar to between-frame (same-film) differences reported in quantitative coronary angiography (QCA). The mean (+/- SD) interstudy difference in coronary artery diameters was 0.16 +/- 0.43 mm, although this was greatly skewed by one subject with poor image plane repositioning. Excluding that subject resulted in a mean (+/- SD) interstudy difference of 0.04 +/- 0.20 mm. The reproducibility of the segmentation software was excellent, with the mean difference between repeat analyses of the images being 0.00 +/- 0.03 mm. The intrastudy variability of coronary artery diameter measurements is low, potentially allowing MR coronary angiography to be used as a tool for the noninvasive assessment of serial changes following pharmacological intervention. A major contributing factor to this is the high reproducibility of the segmentation software. Interstudy variability is approximately three times the intrastudy variability.

Interstudy reproducibility of right ventricular volumes, function, and mass with cardiovascular magnetic resonance

Background Cardiovascular magnetic resonance (CMR) has shown excellent results for interstudy reproducibility in the assessment of left ventricular (LV) parameters. However, interstudy reproducibility data for the more complex-shaped right ventricle in a large study group have not yet been reported. We sought to determine the interstudy reproducibility of measurements of right ventricular (RV) volumes, function, and mass with CMR and compare it with correspondent LV values. Methods Sixty subjects (47 men; 20 healthy volunteers, 20 patients with heart failure, 20 patients with ventricular hypertrophy) underwent 2 CMR studies for assessment of RV measurements with a minimum time interval between each study. Results The overall interstudy reproducibility (range between groups) for the RV was 6.2% (4.2%–7.8%) for end-diastolic volume, 14.1% (8.1%–18.1%) for end-systolic volume, 8.3% (4.3%–10.4%) for ejection fraction (EF), and 8.7% (7.8%–9.4%) for RV mass. RV reproducibility was not as good as for the LV for all measures in all 3 groups, but this was only statistically significant for EF ( P <.01). Conclusions CMR showed good interstudy reproducibility for RV function parameters in healthy subjects, patients with heart failure, and patients with hypertrophy, which suggests that CMR is reliable for serial RV assessment. These data can be used to power sample sizes for longitudinal research studies of RV volume and function. The reproducibility values were similar to, but generally lower than, the reproducibility values for the LV in the same study population, which indicates that sample sizes for RV studies are in general larger than those for LV studies.

Interstudy reproducibility of right ventricular volumes, function, and mass with cardiovascular magnetic resonance*1

Interstudy reproducibility of right ventricular volumes, function, and mass with cardiovascular magnetic resonance*1

Accuracy of One? and Two?Dimensional Algorithms with Optimal Image Plane Position for the Estimation of Left Ventricular Mass: A Comparative Study Using Magnetic Resonance Imaging

The commonly recommended one-dimensional (ID) and two-dimensional (2D) algorithms for left ventricular (LV) mass calculation are limited by assumptions about ventricular geometry and image plane position. To assess the accuracy of these algorithms after eliminating errors associated with image plane position, LV mass was calculated from high quality cardiovascular magnetic resonance imaging (CMR) data sets using ID (modified cube formula; MCF) and 2D algorithms [area-length (AL) and truncated ellipsoid (TE) methods], and the summation of slices (SS) method as reference technique in 25 patients with LV aneurysms, 15 patients with hypertrophic cardiomyopathy, and 10 healthy subjects. Each algorithm in each group overestimated LV mass compared to SS (p <0.05 and p<0.001). In each patient group, the smallest bias to the reference method was observed for the TE algorithm (p<0.001 vs. MCF and p < 0.05 vs. AL). The LV mass interval encompassing the limits of agreement was 120-220 g for MCF, 100-148 g for AL, and 80-136 g for TE. The interstudy reproducibility of the SS technique for the assessment of LV mass was superior compared to the ID and 2D algorithms. We conclude that despite the use of optimized image plane position ID and 2D algorithms are inaccurate for calculation of LV mass in ventricles with normal and distorted LV geometry. Thus, 3D imaging techniques, such as CMR, should be preferred when assessing LV mass.

Accuracy of Quantitative MR Vessel Wall Imaging Applying a Semi?Automated Gradient Detection Algorithm?A Validation Study

Magnetic resonance imaging (MRI) is uniquely suited to study the pathophysiology of arteriosclerosis. So far, magnetic resonance (MR) measurements of vessel dimensions have mainly been done by manual tracing of vessel wall contours. However, such data postprocessing is very time-consuming and has limited accuracy due to difficulties in precise tracing of the thin vessel wall. To assess the accuracy and reproducibility of quantitative vascular MR imaging applying a data analysis method based on (1) vessel wall unwrapping, followed by (2) a gradient detection algorithm for MR data postprocessing. Vascular MR imaging studies were done both in vessel phantoms and in healthy volunteers (n=29) on a clinical 1.5 T MR scanner. A dark blood double-inversion turbo spin echo sequence with fat suppression was applied, with proton-density-weighted and breath-hold acquisition for aortic imaging and T2-weighted acquisition for carotid imaging. Intraobserver and interobserver variability were systematically evaluated by two independent observers. A repeat study within 10 days of the first MRI was performed in 10 of these subjects for assessment of interstudy reproducibility. The semiautomated edge detection software revealed a clear view of the inner and outer vessel wall boundaries both in the phantoms and in the volunteers studied. There was close agreement between MR-derived measurements and phantom dimensions (mean difference of 1.1+/-16.9 mm2, 8.0+/-19.9 mm2, 9.0+/-12.1 mm2 for vessel wall cross-sectional area, inner vessel area, and total vessel area, respectively). Quantification of vessel dimensions was feasible in all 29 healthy volunteers studied. Semiautomated quantification of cross-sectional vessel wall area (mean+/-SD, 253.6+/-208.4 mm2) revealed close correlation for repeated measurements by one or two observers (r=0.99 each). Both intraobserver and interobserver variability of vessel wall area MR measurements were low (mean difference 7.5+/-16.7 mm2 and 14.4+/-24.6 mm2 , respectively). In the repeat study of 10 volunteers, MRI with semiautomated postprocessing quantitation revealed a high correlation and agreement of vessel dimensions between the two scans (r=0.994, mean difference 2.6+/-25.1 mm2). Semiautomated analysis methods can provide approaches that benefit from the human understanding of the image and the computer's ability to measure precisely and rapidly. Thus, by combining the latest MRI methods and semiautomated image analysis methods, we are now able to reproducibly determine the geometric parameters of blood vessels.

Interstudy reproducibility of parameters of left ventricular diastolic function: a Doppler echocardiography study

Background and methods Interstudy reproducibility of echocardiography for the assessment of parameters of left ventricular (LV) diastolic function is disputed. Therefore, we evaluated the reproducibility of echocardiography for assessment of LV diastolic Doppler parameters in 40 consecutive patients (age range: 19-77 years), who underwent 2 echocardiographic examinations by trained sonographers following a standard protocol, in conditions in which intrapatient sources of variability were minimized. Results Interstudy reproducibility of measurements of the ratio of early (E) to late (A) peak velocities of transmitral flow (E/A) at tips of the mitral valve leaflets was found to be very good and substantially greater than analogous measurement obtained at mitral annulus level. Reproducibility of measurement of atrial filling fraction was good both at tips of mitral leaflets and at annular level. Interstudy reproducibility of isovolumic relaxation time and E-wave deceleration time was moderate. Measurements of E-wave propagation rate and the ratio of early (E’) to late (A’) peak velocities of diastolic excursion of lateral mitral annulus (E’/A’) by Doppler tissue were found highly reproducible. Intrastudy between-reading reproducibility of Doppler parameters of LV diastolic function were overall very good, except for E-wave deceleration time. However, 80% confidence interval of absolute between-study differences of diastolic parameters were relatively large, and ranged from −0.11 to +0.19 for E/A at tips of mitral valve; −5 to +9 cm/s for E-wave propagation rate; and −0.69 to +0.19 for Doppler tissue–derived E’/A’. Conclusions Under a standardized echocardiographic protocol and sonographers' training program, echocardiography can be a reproducible method for serial assessment of Doppler parameters of LV diastolic function, especially in cohort studies.

Interscanner reproducibility of cardiovascular magnetic resonance T2* measurements of tissue iron in thalassemia.

To assess interscanner reproducibility of tissue iron measurements in patients with thalassemia using gradient echo T2* measurements on two different MRI scanners. Twenty-five patients with thalassemia major had liver and myocardial T2* assessment using a Picker Edge 1.5T Scanner and a Siemens Sonata 1.5T scanner, with similar gradient echo sequences. In a subset of 13 patients, two scans on the Siemens scanner were performed to assess interstudy reproducibility. There was a highly significant, linear correlation between T2* values obtained for both the heart (r = 0.95) and the liver (r = 0.99) between scanners. The mean difference, coefficient of variability, and 95% confidence intervals between scanners were 0.8 msec, 9.4% and -5.0 to 6.7 msec for the heart; and 0.9 msec, 7.9% and -2.0 to 3.9 msec for the liver. The interstudy mean difference and coefficient of variability on the Siemens scanner was 0.3 msec and 4.8% (r = 0.99) for the heart, and 0.04 msec and 1.9% (r = 0.99) for the liver. The T2* technique for measuring tissue iron is reproducible between the two manufacturers' scanners. This suggests that the widespread implementation of the technique is possible for clinical assessment of myocardial iron loading in thalassemia.