Cardiac Function by MRI in Congenital Heart Disease: Impact of Consensus Training on Interinstitutional Variance
King's College London BHF Centre, Division of Imaging Sciences, NIHR Biomedical Research Centre at Guy's and St Thomas' NHS Foundation Trust London, United Kingdom. Journal of Magnetic Resonance Imaging
(Impact Factor: 3.21).
11/2009; 30(5):956-66. DOI: 10.1002/jmri.21948
To investigate the impact of interinstitutional variance (=interobserver variance between institutions) for volumetric and flow cardiac MR (CMR) data and if training on image reading could improve bias.
In a three-center study, a total of 32 adults with repaired Tetralogy of Fallot and 23 controls underwent CMR using standardized protocols for ventricular volumes/mass (by transverse and short-axis cine-MRI) and pulmonary/aortic blood flow by velocity-encoded MRI (VEC-MRI). Data were analyzed blinded and independently in each institution by experienced readers. Interinstitutional variance was determined before/after training on consented guidelines for image analysis.
In patients, initial interinstitutional variability of right ventricular parameters was substantial but decreased by training. On transverse planes, variation coefficient for end-diastolic/systolic volumes and ejection fraction decreased from 22%, 19%, and 19% to 7%, 10%, and 8%, respectively (P < 0.025). Left-ventricular variation coefficients improved for end-diastolic and stroke volumes from 8% and 15% to 4% and 6%, respectively (P < 0.007). For short-axis volumetry training resulted in narrowed limits of confidence. Variability did not significantly change in the controls. There was no significant difference between transverse/short-axis MRI. Interinstitutional variance for VEC-MRI in patients/controls was low (<4%).
Interinstitutional variance is an important source of variability in volumetric but not in flow CMR. Such variance can be reduced effectively by consented training.
Figures in this publication
Available from: Ingo Dähnert
- "CMR image analysis was performed by two fully blinded observers (M.G. and J.H.) with 13 and 5 years of experience in CMR, respectively, using a Philips ViewForum workstation (Version 4.2; Cardiac Evaluation Package) in our CMR laboratory, which has demonstrated expertise in the imaging of congenital heart disease and has proven low intra- and inter-observer variability in the assessment of biventricular volumes and function [17–19]. Endocardial and epicardial borders were manually traced during end systole and end diastole in each slice. "
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Systemic right ventricle (RV) hypertrophy and impaired function occur after atrial switch for dextro-transposition of the great arteries (d-TGA). Echocardiography is limited in its ability to assess the RV. We sought to evaluate systemic RV myocardial-mass index (MMI) and function after atrial switch and to analyse the role of hypertrophy for ventricular function with special consideration of the interventricular septal (IVS) movement.
Thirty-seven consecutive patients (median age 22.9 years) after atrial switch were studied using cardiac magnetic resonance imaging (1.5T Intera, Philips) with a dedicated 5-channel phased-array surface cardiac coil. Cine steady-state free-precession sequences were acquired to obtain myocardial masses and function. The systolic movement of the IVS was defined as positive when moving towards the centroid of the RV and was defined as non-positive otherwise. Patient parameters were compared to controls.
The systemic RVs were significantly larger (p < 0.001) than the left ventricles of the control group, systolic function was significantly impaired (p < 0.001) and MMI including the IVS was comparable (p = n.s.). RV-MMI excluding the IVS and RV ejection fraction (EF) demonstrated a quadratic correlation (r = 0.6, p < 0.001), meaning that patients with RV-MMI ≤29 g/m2 and >68 g/m2 had a reduced level of systolic function. Positive septal movement improved RV function compared with non-positive septal movement (p = 0.024).
There seems to be a range of beneficial RV hypertrophy after atrial switch in which a sufficient RV-EF can be expected. A positive septal movement, probably the result of hypertrophic septal RV fibres, improves RV function and might be regarded as a beneficial contraction pattern.
Clinical Research in Cardiology 06/2012; 101(12). DOI:10.1007/s00392-012-0485-6 · 4.56 Impact Factor
Available from: Andreas Schuster
- "The parameter with highest variability at rest in the current study was longitudinal strain of the RV indicating that the analysis of the thin-walled RV with CMR-FT is not yet adequately accurate. This might also be explained by difficulties in endocardial tracking due to difficulty in accurately following the tricuspid valve annulus motion with the CMR-FT software; and RV trabeculations that also lead to greater variability in RV volumetric assessment . The most robust parameter in our study was circumferential strain of the LV; which might be clinically valuable. "
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ABSTRACT: Dobutamine stress cardiovascular magnetic resonance (DS-CMR) is an established tool to assess hibernating myocardium and ischemia. Analysis is typically based on visual assessment with considerable operator dependency. CMR myocardial feature tracking (CMR-FT) is a recently introduced technique for tissue voxel motion tracking on standard steady-state free precession (SSFP) images to derive circumferential and radial myocardial mechanics.We sought to determine the feasibility and reproducibility of CMR-FT for quantitative wall motion assessment during intermediate dose DS-CMR.
10 healthy subjects were studied at 1.5 Tesla. Myocardial strain parameters were derived from SSFP cine images using dedicated CMR-FT software (Diogenes MRI prototype; Tomtec; Germany). Right ventricular (RV) and left ventricular (LV) longitudinal strain (EllRV and EllLV) and LV long-axis radial strain (ErrLAX) were derived from a 4-chamber view at rest. LV short-axis circumferential strain (EccSAX) and ErrSAX; LV ejection fraction (EF) and volumes were analyzed at rest and during dobutamine stress (10 and 20 μg · kg⁻¹· min⁻¹).
In all volunteers strain parameters could be derived from the SSFP images at rest and stress. EccSAX values showed significantly increased contraction with DSMR (rest: -24.1 ± 6.7; 10 μg: -32.7 ± 11.4; 20 μg: -39.2 ± 15.2; p < 0.05). ErrSAX increased significantly with dobutamine (rest: 19.6 ± 14.6; 10 μg: 31.8 ± 20.9; 20 μg: 42.4 ± 25.5; p < 0.05). In parallel with these changes; EF increased significantly with dobutamine (rest: 56.9 ± 4.4%; 10 μg: 70.7 ± 8.1; 20 μg: 76.8 ± 4.6; p < 0.05). Observer variability was best for LV circumferential strain (EccSAX ) and worst for RV longitudinal strain (EllRV) as determined by 95% confidence intervals of the difference.
CMR-FT reliably detects quantitative wall motion and strain derived from SSFP cine imaging that corresponds to inotropic stimulation. The current implementation may need improvement to reduce observer-induced variance. Within a given CMR lab; this novel technique holds promise of easy and fast quantification of wall mechanics and strain.
Journal of Cardiovascular Magnetic Resonance 10/2011; 13(1):58. DOI:10.1186/1532-429X-13-58 · 4.56 Impact Factor
Available from: Elżbieta Megiel
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ABSTRACT: As an extension of our investigation of the effect of chain length of an n-alkane, as well as the number and position of methyl groups in a pyridine ring, excess molar volumes, VE, for a 2,4,6-trimethylpyridine + a C6 to C10 n-alkane have been measured at 25 °C. For these systems no VE values were available in the literature. We have compared the experimental VE data for the investigated systems with the results calculated by applying the Prigogine-Flory-Patterson theory (PFP) (Flory et al., 1964, 1982), Extended real associated solutions by Heintz (1985) (ERAS), and Treszczanowicz-Benson-Patterson (TB), (Treszczanowicz et al., 1989). We concluded that Treszczanowicz-Benson-Patterson Method (Treszczanowicz et al., 1989) gave the best results of VE.
Fluid Phase Equilibria 12/1995; 113(1):139-149. DOI:10.1016/0378-3812(95)02767-1 · 2.20 Impact Factor
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