Measuring Optical Nerve Diameter in Persian Cat Using MRI and Three Dimensional Ultrasonography

The ocular structures are detectable using ultrasonography and magnetic resonance inaging(Mri) due to the presence of a considerable amount of fluid around vitreous and anterior chambers. using modern techniques may be helpful in assessing accurately normal structures of the retro bulbar space.

A total of ten normal persian cats,(5 males, 5 females), weighting 3±1.1 kg, underwent ultrasonographic examination. a GE Voloson ultrasonography machine and three-di- mensional (3D) linear array transducers (5-10 MHz) were used. Mri was performed with a 1.5 t GE scanner and a phased array human eye coil. the field of view ranged from 4 to 8 cm. transverse, sagittal and dorsal spin-echo t1 and t2 weighted images were acquired in all samples.

The mean optical nerve diameter in males by 3D-ultrasonography and Mri were 1.85mm (SD=0.002) and in females it was 1.86mm (SD=0.001). no significant difference was observable between ocular nerve measurements in male and female cats and left and right eyes using 3D-ultrasonography or Mri (p-value<0.05).

The 3D-ultrasonography provides useful images for diagnostic purposes and lesions of the caudal part of the orbit. the results of the eye 3D-ultrasonography in cats showed marked advantages in image acquisition for interpretation of all aspects of the ocular structures. this study suggests that using 3D-ultrasonography in veterinary ophthal- mology may be better than Mri because the images of 3D-ultrasonography are more flexible and can provide all the voluntary views. on top of that, the scanning period is shorter and anaesthesia is not required when using 3D-ultrasonograph