Accuracy of knowledge-based reconstruction for measurement of right ventricular volume and function in patients with tetralogy of Fallot.
ABSTRACT We tested the accuracy and reproducibility of knowledge-based reconstruction (KBR) for measuring right ventricular (RV) volume and function. KBR enables rapid assessment of the right ventricle from sparse user input by referencing a database. KBR generates a 3-dimensional surface to fit points that the user enters at anatomic landmarks. We measured the RV volume using KBR from magnetic resonance images in 20 patients with repaired tetralogy of Fallot at end-diastole and end-systole. We entered points in the long- and short-axis and/or oblique views. The true volume was computed by manually tracing the RV borders for 3-dimensional reconstruction using the piecewise smooth subdivision surface method. The reference database included 54 patients with tetralogy of Fallot patients. The KBR values agreed closely with the true values for the end-diastolic volume (r = 0.993), end-systolic volume (r = 0.992), and ejection fraction (EF; r = 0.930). KBR slightly overestimated the end-diastolic volume (4 +/- 10 ml, p = NS), end-systolic volume (1 +/- 9 ml, p = NS), and EF (4 +/- 3%, p = NS). No bias in the error was found by Bland-Altman analysis (p = NS for end-diastolic and end-systolic volume and EF). The KBR volumes had approached the true volumes (235 +/- 93 vs 243 +/- 93, p = 0.012, r = 0.978 for end-diastolic and end-systolic volumes combined) already after the first run and the entry of 19 +/- 3 points. In conclusion, KBR provided accurate measurement of the RV volume and EF with minimal user input. KBR is a clinically feasible alternative to full manual tracing of the heart borders from imaging data.
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ABSTRACT: 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.The International Journal of Cardiovascular Imaging 01/2005; 20(6):509-16. · 2.65 Impact Factor
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ABSTRACT: The method used to delineate the boundary of the right ventricle (RV), relative to the trabeculations and papillary muscles in cardiovascular magnetic resonance (CMR) ventricular volume analysis, may matter more when these structures are hypertrophied than in individuals with normal cardiovascular anatomy. This study aimed to compare two methods of cavity delineation in patients with systemic RV. Twenty-nine patients (mean age 34.7 +/- 12.4 years) with a systemic RV (12 with congenitally corrected transposition of the great arteries (ccTGA) and 17 with atrially switched (TGA) underwent CMR. We compared measurements of systemic RV volumes and function using two analysis protocols. The RV trabeculations and papillary muscles were either included in the calculated blood volume, the boundary drawn immediately within the apparently compacted myocardial layer, or they were manually outlined and excluded. RV stroke volume (SV) calculated using each method was compared with corresponding left ventricular (LV) SV. Additionally, we compared the differences in analysis time, and in intra- and inter-observer variability between the two methods. Paired samples t-test was used to test for differences in volumes, function and analysis time between the two methods. Differences in intra- and inter-observer reproducibility were tested using an extension of the Bland-Altman method. The inclusion of trabeculations and papillary muscles in the ventricular volume resulted in higher values for systemic RV end diastolic volume (mean difference 28.7 +/- 10.6 ml, p < 0.001) and for end systolic volume (mean difference 31.0 +/- 11.5 ml, p < 0.001). Values for ejection fraction were significantly lower (mean difference -7.4 +/- 3.9%, p < 0.001) if structures were included. LV SV did not differ significantly from RV SV for both analysis methods (p = NS). Including structures resulted in shorter analysis time (p < 0.001), and showed better inter-observer reproducibility for ejection fraction (p < 0.01). The choice of method for systemic RV cavity delineation significantly affected volume measurements, given the CMR acquisition and analysis systems used. We recommend delineation outside the trabeculations for routine clinical measurements of systemic RV volumes as this approach took less time and gave more reproducible measurements.Journal of Cardiovascular Magnetic Resonance 01/2008; 10:40. · 4.44 Impact Factor
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ABSTRACT: We present a general method for automatic reconstruction of accurate, concise, piecewise smooth surface models from scattered range data. The method can be used in a variety of applications such as reverse engineering - the automatic generation of CAD models from physical objects. Novel aspects of the method are its ability to model surfaces of arbitrary topological type and to recover sharp features such as creases and corners. The method has proven to be effective, as demonstrated by a number of examples using both simulated and real data. A key ingredient in the method, and a principal contribution of this paper, is the introduction of a new class of piecewise smooth surface representations based on subdivision. These surfaces have a number of properties that make them ideal for use in surface reconstruction: they are simple to implement, they can model sharp features concisely, and they can be fit to scattered range data using an unconstrained optimization procedure.A. S. Glassner, (ed), Computer Graphics (Siggraph'94 proc.), Annual Conference Series, pp 295-302, July 1994. 01/1994;