HHe-3 MRI Lung Volume Compartments and VH Indicators
For the total sample (n=60) the four volume compartments (E-supplement
Table E-1) included the non-ventilated volume (2.8 % total volume),
hypoventilated volume (16.4 % total volume), ventilated volume (27.8%
total volume) and well-ventilated volume (53% total volume). Indices of
VH included the Vdef % (1.29 ± 3.13), the VHI %, (17.59 ± 13.36) and
the VVI % (82.40 ± 13.36). The VHI % and VVI % had Gaussian
distributions, but not the Vdef % (E-supplement Figure E-1).
To examine whether volume sub-compartments varied significantly in
children with greater VH, sub-volumes were compared according to the
distribution of the VHI % (Figure 1). The non-ventilated and
hypoventilated compartments were significantly higher, whereas the
well-ventilated compartment was significantly lower, in children with
VHI % values in the upper 25th %ile compared to the
lower 25th %ile and the middle
25th-75th %iles. Thus, greater VH
was accompanied by greater non-ventilated and hypoventilated lung
volumes, lower well-ventilated volume, but no significant change in the
ventilated volume compartment.