DISCUSSION
In this study, we demonstrate strong agreement between Tomtec Image
Arena and VMS+ 3.0 for left ventricular and left atrial volumetric
calculations from pediatric 3D DICOM datasets over a wide range of age
and BSA. We provide formulas for linear, optimally curve-fitted, and
log-log transformed regressions using both software algorithms, and the
distribution parameters (average, standard deviations) for the indexed
values from the optimal fit regression. This permits calculation of
normal ranges and z-scores specific to the algorithms used. We also
demonstrate excellent to good inter and intraobserver agreement for
these techniques by intraclass correlation.
Three-dimensional echocardiographic imaging has emerged as a useful
adjust to standard 2-dimensional echocardiography in volumetric
measurement, and in some cases is promoted as the preferable method. Its
main advantage is measurement of the atrial or ventricular chamber
without reliance on geometric assumptions and (usually) only two 2D
imaging planes. The replicability of 3DE volumetric measurement of the
LV has been shown to be superior to 2D calculations and 3D LV volumes
are more comparable to those derived from the gold standard, cardiac
magnetic resonance imaging (CMR)5,6, 7,25,26,27.
Therefore 3DE volumetric imaging is becoming an important tool in risk
stratification, pre-procedural planning, and assessment of treatment in
pediatric and adult cardiac populations. 3DE offers a relatively
inexpensive and readily available tool at the bedside to assess cardiac
chamber volumes and a viable alternative modality when CMR is not
feasible or contraindicated.
Measurement of the LA volume has been increasingly recognized as an
important component of echocardiographic analysis, with robust data
showing prognostic importance in cardiac failure, as well as in
assessment of progressive mitral valve disease. Assessment of the phases
of LA function (reservoir, conduit and atrial contraction), while beyond
the scope of this study, can be assessed with 3DE. Changes in these
phases may provide useful early warnings of progressive disease before
detectable LV diastolic function becomes apparent.
This study, to the best of our knowledge, is the first to compare TomTec
to VMS software in measuring left cardiac chambers. Given that TomTec
software has been previously validated against CMR in recently published
multi-center studies in pediatrics; we provide in this study an
alternative software algorithm to currently available software with
comparable accuracy and efficiency in measuring left cardiac chambers
using real time 3DE. Both algorithms performed particularly well in
patients with smaller BSA compared to larger BSA. This could be in part
due to higher spatial and temporal resolution images obtained in smaller
children, and the smaller chest excursion during breathing, leading to
fewer stitch artifacts. It was true despite the higher heart rates in
younger children, and the benefits of older patient cooperation and
ability to understand instruction for breath holding during multi-beat
acquisitions. Tomtec LA and LV measurements were on average slightly
higher than VMS measurements which should be considered when using the
two software interchangeably.
In considering utility in clinical practice, both VMS+ 3.0 and Tomtec
Image Arena have quick post processing times (VMS on average being
slightly faster, Table 5) for both LV & LA with means between 1.5 - 2
minutes for VMS and 3 minutes for TomTec for each chamber. Our analysis
time did not include the time required to import datasets into the
offline software packages, which may be longer than the analysis time
itself. Integration of 3DE analysis packages with general
echocardiographic reporting software, allowing direct launch of the
analysis, and automatic upload of the measurements obtained can help to
streamline this process, and encourages routine usage of these tools.
Direct measurement on echocardiographic imaging modalities can also
facilitate this process for some workflows.