MRI assessment of lung parenchymal motion in normal mice and transgenic mice with sickle cell disease.
OBJECTIVE
To test the feasibility of a method to quantify regional pulmonary parenchymal motion via nonrigid registration algorithm at small animal scales.


METHODS
Voxel-wise displacement vector field maps were generated between end-inspiratory and end-expiratory coronal thoracic MR images on normal mice (N = 5) to analyze the magnitude and direction of parenchymal motion in the segmented regions. The analysis was repeated before and after short-term exposure to hypoxia to demonstrate the effect of hypoxia on the respiratory motion in transgenic (Tg) mice with sickle cell disease (SCD) (N = 4).


RESULTS
Normal mice revealed that the right and left lungs moved symmetrically but that there was greater movement in the lower regions than in the upper regions. Calculated strain was uniform in the entire lung. In the Tg mice, the pulmonary motion before hypoxia was similar to that observed in the normal mice. Upon exposure to hypoxia, the displacement magnitude reduced and the direction of motion in some areas became distorted.


CONCLUSIONS
MR quantification of pulmonary motion was feasible in mice and the principle that the method could detect mechanical abnormalities due to pathologic changes was proven. Quantification of pulmonary motion has the potential to lead to earlier disease diagnosis and better monitoring of disease treatments.
Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
Shigeru
S
Kiryu
Tessa
T
Sundaram
Shigeto
S
Kubo
Kuni
K
Ohtomo
Toshio
T
Asakura
James C
JC
Gee
Hiroto
H
Hatabu
Masaya
M
Takahashi
D000704:Analysis of Variance; D000755:Anemia, Sickle Cell / Q000503:physiopathology*; D000818:Animals; D001696:Biomechanical Phenomena; D005240:Feasibility Studies; D000860:Hypoxia; D008168:Lung / Q000503:physiopathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D009068:Movement / Q000502:physiology; D018709:Statistics, Nonparametric