Abstract
Purpose:
Evaluating eye dimensions is crucial in studies of animal models of eye diseases. However, performing these measurements in alive mice is challenging. The aim of this study was to develop a method for quantitating eye morphology using planar surface MRI coil.
Methods:
Aged (18 months) C57Bl/6 female mice (n=5) were anaesthetized with isoflurane (4% in oxygen - induction, 1.5-2% - maintenance) and placed in 7T small animal-dedicated magnetic resonance tomograph (BioSpec 70/30USR; Bruker BioSpin, Ettlingen, Germany). Small planar surface receive coil (internal diameter=10 mm, Bruker BioSpin, Ettlingen, Germany) was placed over left eye of the imaged animal. High resolution structural imaging with TURBORARE T2 sequence (TR=2700ms, TEeff=30ms, RARE factor=8, NA=12, spatial resolution=0.062mm x 0.062mm, slice thickness=0.3mm, slices=7, scan time=16min) was performed. Basic ocular dimensions and anterior chamber angle were measured manually using OsiriX software (Pixmeo, SARL, Bernex, Switzerland).
Results:
Mean anterior chamber depth in C57Bl/6 mice was 0.464 mm (SD ±0.040) and anterior chamber angle (ACA) 24.98° (SD ±5.599), vitreous chamber depth (VCD) 0.465 mm (SD ±0.033), axial length (AL) 3.586 mm (SD ±0.079) and horizontal length (HL) 3.394 mm (SD ±0.061) of the eyeball, lens thickness (LT) 2.146 mm (SD ±0.059) and optic nerve diameter (ON) 0.250 mm (SD ±0.0520), retinal thickness (RT) 0.206 mm (SD ±0.018).
Conclusions:
High resolution magnetic resonance imaging of the eye with use of small planar coil provide reproducible and consistent measures of key dimensions of eyeball. These results are consistent with results obtained with optical coherence tomography in C57Bl/6 mice [Chou et al. 2011, IOVS 52:3604-3612].