Model versus non-model based left ventricular volumetry - A matter of imaging modality or quantification software?

Kai Thorsten Laser, Peter Barth, Miriam Bunge, Gregor Dachner, Hermann Esdorn, Marcus Fischer, Jürgen Gieseke, Eugen Sandica, Deniz Kececioglu, Wolfgang Burchert, Hermann Körperich

Abstract


Objective: To compare the modalities 3D-echocardiography (RT3DE) and cardiac magnetic resonance as well as semiautomatic non-model-based and model-based quantification software (SWP-MRI and SWT-MRI) regarding accuracy and agreement of left ventricular functional indices.

Methods: 9 asymmetrically shaped gel phantoms (range: 20-350ml), 24 healthy children (age=11.4±3.3y) and 11 patients with abnormally shaped left ventricles (22.0±17.0y) were prospectively investigated. 3D-echocardiography was performed using a Vivid 7 ultrasound machine (V3 matrix transducer); postprocessing was done with a model-based analysis strategy (SWT-echo). CMR datasets were obtained using a multi-slice multi-phase steady‑state-free-precision acquisition (TR/TE/flip=2.8msecs/1.4msecs/60°) with a 1.5T MR system. Volume quantification was done using the same model-based software for CMR as well as non model-based software based on the summation of discs method. Agreement of EDV, ESV and EF between SWT-echo, SWP-mri vs. SWT-mri was determined by Bland Altman analysis.

Results: Phantom study revealed high accuracy (<1%) for SWT-echo and SWP-mri as well as a moderate underestimation for SWT‑mri (13%). Agreement between SWP-mri and SWT-echo was superior in volunteers [mean; limits-of-
agreement: EDV(5.3%; -20.1 to 30.8%), ESV(-1.3%; -41.6 to 38.9%), EF(4.0%; -12.0 to 19.9%)] with only slight underestimation by  RT3DE in patients [EDV(11.5%; ‑18.5 to 41.4%), ESV(13.0%; -5.4 to 31.5%), EF(‑6.9%; -49.9 to 36.1%)]. Comparing SWT-echo with SWT-mri revealed volume underestimation of EDV (9.8; -20.5 to 40.0%) and overestimation of ESV (-9.6; -60.1 to 41.0%) in volunteers by SWT-mri resulting in underestimation of EF (12.6;-9.6 to 34.9). In patients minor differences between SWT-echo and SWT-mri were observed [EDV (0.6%; -28.2 to 29.4%), ESV (-2.4%; -38.2 to 33.4%), EF(9.3%; -35.7 to 54.3%)]. Compared to our reference SWP-mri both model-based techniques moderately underestimated EDV (SWT-MRI 12.1%; ‑2.1 to 26.4%, SWT-echo 11.5%; -18.5 to 41.4%) and ESV (SWT-mri 10.6%; -21.2 to 42.4%, SWT-echo 13.0%; -5.4 to 31.5%)  resulting in quite precise  EF(SWT-MRI  2.4%, -23.7 to 28.5%).

Conclusion: Accuracy and reliability of left ventricular indices are excellent for RT3DE assessed by model based approach compared to non-model-based CMR approach in phantoms and healthy volunteers with minor volume underestimation in atypically shaped moving ventricles. Minor agreement was present if the model-based CMR software was used for determination of ventricular volumes.

Full Text: PDF DOI: 10.5430/jbgc.v3n2p54

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Journal of Biomedical Graphics and Computing
ISSN 1925-4008 (Print)   ISSN 1925-4016 (Online)
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