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.