Abstract
Objective: To evaluate deformable slice-to-volume registration (DSVR) to
calculate 3D-segmented total lung volume (TLV) in fetuses with
congenital diaphragmatic hernia, congenital lung lesions and healthy
controls, with comparison to 2D-manual segmentation. To establish
normogram of TLV calculated by DSVR in health control fetuses.
Design: Pilot study
Setting: Single regional fetal medicine referral centre
Sample:Fetal MRIs performed for clinical indications (abnormal cases) or
as research participants (healthy controls)
Methods: Sixteen MRI datasets of fetuses (22-32 weeks GA). Diagnosis:
CDH(n=6, one with coexisting BPS), CPAM(n=2), and healthy controls(n=8).
DSVR was used for reconstruction of 3D isotropic (0.85 mm) volumes of
the fetal body followed by semi-automated lung segmentation. The
resulting 3D TLV were compared to the traditional 2D-based volumetry,
and abnormal cases referenced to a normogram produced from 100 normal
fetuses whose TLV was calculated by DSVR.
Main Outcome Measures: Concordance with 2D-volumetry assessed with
Bland-Altman analysis, results of segmentations presented visually.
Observed/Expected values were calculated for abnormal cases based upon
the normogram.
Results: DSVR-derived TLV values have high correlation with the 2D-based
measurements but with a consistently lower volume; bias
-1.44cm3 [95% limits: -2.6 to -0.3] with improved
resolution able to exclude hilar structures even in severe motion
corruption or in cases of very low lung volumes. lung hypoplasia.
Conclusions: Application of DSVR for fetal MRI is beneficial for the
analysis of motion corrupted scans and does not suffer from the
interpolation error inherent in currently applied 2D-segmentation as per
current clinical practice. It increases information content of acquired
data in terms of visualising organs in 3D space and quantification of
volumes, which we believe will improve counselling and surgical
planning.
Keywords: Fetal MRI; congenital diaphragmatic hernia;
congenital lung lesion; congenital pulmonary airway malformation;
bronchopulmonary sequestration; lung volume