Evaluation of the accuracy of volume determination on the orbit and eyeball using MRI

This study reports a calibration carried out on phantoms simulating the orbit and eyeball to evaluate the accuracy of volumetric determination using MRI DICOM (Digital Imaging and Communication in Medicine) images. Ten tailor-made spherical silicon balls ranging in size from 5 to 14 cm3and 10 silicon moulds of orbits from 10 human dried skulls were used to simulate the eyes and orbits, respectively. The CISS (Constructive interference in steady state, TR/TE = 16/8 ms) T2-weighted sequence was taken using a Siemens MRI scanner. The volume of each phantom was computed and compared with the known physical volumes. The computed and physical volumes were highly correlated for both eyeball (r = 0.997) and the orbit (r = 0.992) phantoms. Coefficients of variation of the computed and physical volumes were low. Consequently, it is possible to apply a calibration value to the computed volume to derive the physical volume with a high level of confidence. We conclude that with appropriate calibration, it is viable to use MRI DICOM images to derive the volume of the eyeball and the orbit.