Supplemental Table 1. Processing using BP-SPECT, TOMPOOL and QBS
BP-SPECT BP-SPECT is count-based, automatic and thus reproducible. Filtered
images are backprojected to form transaxial slices, reoriented manually
in order to include the entirety of both ventricles in the field of views.
There is no operator interference in the determination of the size and the
shape of regions used for ventricles segmentation. According to the
literature, mid-ventricular locations are automatically determined by
searching for maximum activity in volumetric regions likely to correspond
to the RV in the short-axis [SA], horizontal long-axis [HLA] and vertical
long-axis [VLA]. RVEDV VLA is defined by the contiguous voxels that
contain counts ≥ 35% of the maximum end-diastolic counts found over
the entire RV volume (RVEDV VLA) while avoiding the right and
pulmonary artery based on Fourier phase images. Then, RVESV VLA is
generated based on the ED region and phase images. Finally, RVEDV
SA is generated by voxels that have > 35% of maximum RVEDV counts
in SA images while avoiding LV and pulmonary artery areas. The
pulmonary valve plane is placed as high as necessary to include all
structures with counts that increase synchronously with LV. Biventricular
EFs are computed from systolic count changes within voxels inside
identified RVEDV and RVESV that have > 35% of maximum counts.(18).
TOMPOOL Data are transferred to TOMPOOL as Dicom files (Horizontal Long
Axis). We used the default options: down-sampling on 8 times frames,
threshold at 30% of the maximal activity, approximation of the ejection
curves using a reference curve (9) with 15 iterations, 80% maximal
compression, and 50% minimal slope. The operator-dependent steps of
the procedure are the localization of the valvular, septal, and
infundibular planes by detecting
change in shape and activity.
According to the previous studies (10-13), the semi-automatic
segmentation procedure is based on a watershed algorithm. Voxels
whose value is less than 30% of the maximal activity in the acquisition
are set to zero. The scintigraphic images are segmented using a fully 4D
immersion approach taking adjacent slices and time frames into
consideration. The 4D voxel groups generated by the watershed
algorithm are then aggregated, depending on the relative position of
their barycentre with respect to the septal and valvular planes, to build
up three 4D regions (left ventricular, right ventricular, and extraventricular). Voxels belonging to the right ventricle and located above
the infundibular plane are excluded. Further manual correction of the
produced ventricular regions was not performed.
QBS
The main difference between this algorithm and the one used in
previous versions of the software is the increased robustness introduced
by the coupling of the LV and RV surfaces. The most automatic
procedure was utilized in order to obtain an optimal reproducibility.
Filtered images were backprojected to form transaxial slices, which were
reoriented manually in order to include the entirety of both ventricles in
the field of views. QBS is now a count-threshold based method but used
to be a gradient-based method and the procedure was mostly defined
for the analysis of the left ventricle (1, 7, 14, 15). According to the
literature, the gradient based procedure is described above. The first
step is to automatically approximate a static endocardial surface with a
deformable ellipsoid (relative counts and counts density gradients are
used). Then, a dynamic endocardial surface is computed for each
gating-time interval (sampling) using temporal Fourier analysis of
volumetric count density information. The plane of the pulmonary valve
is then positioned and RV is separated from pulmonary artery: it has
been observed that it rarely extends more than 2 pixels above the
anterior wall or below the inferior wall of the identified LV limits. EF
calculations were initially geometric (based on the number of voxels in
EDV and ESV), but they are count-based in the newest version. The
new count-based segmentation algorithm operates in consecutive steps:
initial filtering and VCC calculation to separate ventricles, atria and
extra-cardiac structures; ventricular surface fit (one surface surrounding
both LV and RV); septal surface fit (one surface describing the
interventricular septum); surface resampling into separate LV and RV
surfaces; optional RV pulmonary conus truncation; ROI computation
based on selected threshold; count-based calculations (using counts
and number of voxels). Each surface fit uses a weighting scheme that
takes into account counts, first and second derivatives along rays
defined in a local coordinate system.
Supplemental Table 2. CMR: parameters of acquisition and processing.
CMR imaging was performed according to CMR guidelines and using the optimal pulse
sequences. Images were acquired on two 1.5-T scanners (Magnetom Avanto 1.5T, Siemens;
Ingenia 1.5T, Philips) with multiplane localizers. The parameters of acquisition parameters
and the processing are described in Supplemental Table 2. The best cut-off values in order
to diagnose a dilatation of the RV or an impairment of the right function were calculated
according to the normal values obtained in previous MRI studies (EDV>88mL/m², EF≤45%,
CO<4L/min)(16), (17). The cut-off value for EDV enlargement was defined as superior to
167mL.
We used two protocols of cine cardiac MR imaging: Single-breath-hold-true-Fast Imaging
with Steady-state Precession [FISP] (Siemens, FOV: 380mm, slice thickness: 8mm with
0mm interslice gaps,TR: 24.96ms, TE: 1.56ms, Flip Angle:80°) and Balanced Turbo FieldEcho (TFE) (Philips, FOV: 320mm, slice thickness: 8mm with 0mm interslice gaps, TR: 3ms,
TE: 1.51ms, TFE factor 16, Flip Angle:60°). During breath-holding, prospective ECG-gated
cine CMR was performed with 35 frames per cardiac cycle. The parameters were assessed,
on 10 to 12 short axis contiguous slices from tricuspid valves to apex.
Two experimented radiologist examined images off-line using ARGUS software (v4.02,
Siemens). Those two physicians were blinded from the results from the physicians
performing the T-ERNV calculations and were therefore different physicians.
Contours of the endocardial border were drawn manually on short axis on all phases. The
operator defined visually the basal slice, the apical slice, ES and ED. CMR values were
derived by the modified Simpson’s rule from regions that were defined to conform to
endocardial borders. Ventricular volumes were determined as the sum of the slice cavity
volumes.
In the basal slice of the short axis, both in ED and ES, only the portion of the right ventricle
outflow tract below the level of the pulmonary valve was included. For the inflow part of the
RV, the blood volume was excluded from the RV volume if the surrounding wall was thin and
not trabeculated since it was considered to be in the right atrium. The apical slice was the
last slice containing blood in the cavity. Papillary muscles and trabeculations were included
in the endocardial contouring to improve reproducibility
Supplemental Figure 1. Automatic delineation of the endocardial contour by BPSPECT. Images acquired in short-axis [SA], horizontal long-axis [HLA] and vertical longaxis[VLA] are compared in four patients.A delineation of the RV (yellow) and of the left
ventricle (white) according to BP-SPECT is showed in three patients (B, C and D) and
compared to MRI (A). This figure illustrates the absence of anatomical information on TERNV, the complex shape of the right ventricle and thus the interest of automatic software.
Supplemental Figure 2. Semi-automatic definition of the valve planes by TOMPOOL.
Horizontal-long-axis tomographic slices are showed in five patients. This figure illustrates the
fact that the manual delineation of the right ventricle would be time consuming and that the
delineation of the endocardial contour is easier when the right ventricle is larger. TOMPOOL
being a semi-automatic software, the operator defines manually the valve planes and should
theoretically be more reliable and appropriate in order to assess RV function. However the
manual delineation of the valve plane leads to a decrease reproducibility.
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