Reference ranges for the diameter of the right ventricular outflow tract
by cardiovascular magnetic resonance and comparison with
echocardiographic measurements
Abstract
Introduction We aimed to provide reference ranges for the right
ventricular outflow tract (RVOT) diameter by cardiovascular magnetic
resonance (CMR) in children and compare the measurements with
two-dimensional (2D) transthoracic echocardiography (TTE). Methods We
measured the RVOT diameter in 49 children with normal RVOT anatomy on
balanced steady-state free precession (bSSFP) CMR images in the strict
transverse and sagittal views, and on 2D TTE images in parasternal short
axis (PSAX) and parasternal long-axis (PLAX) views. Results Based on 63
measurements, we obtained the following mean RVOT diameters and their
reference ranges, indexed to body surface area: 15.2 mm/m2 (7.0-23.3
mm/m2) in the strict transverse view, and 14.0 mm/m2 (7.8-20.2 mm/m2) in
the strict sagittal view. Pearson correlation showed a very strong
correlation between the CMR strict transverse view and the 2D TTE PSAX
view (r=0.84; p<0.0001), and a strong correlation between the
CMR strict sagittal view and the 2D TTE PLAX view (r=0.78;
p<0.0001). The Bland-Altman analysis showed poor agreement
between the CMR strict transverse view and the 2D TTE PSAX view (bias
-3.34 mm/m2 or -16.6%), and between the CMR strict sagittal view and
the 2D TTE PLAX view (bias -3.90 mm/m2 or -19.7%). Conclusions There is
strong correlation but poor agreement between the measurements of the
RVOT diameter in the strict transverse and sagittal views by CMR and the
similar PSAX and PLAX views by 2D TTE. The static bSSFP CMR images in
the strict transverse and sagittal views can’t be used to define RVOT
dilatation in children