MRI scan of the Orbits / Eye

Sunday, September 18, 2016

Orbits MRI Scan

MRI scan of the orbits is usually done to study the Proptosis, Visual Disturbance and evaluation of orbital or ocular mass lessions.

Equipment use on Orbit MRI

  • Small surface coil for globe and orbit
  • Quadrature head coil or multi coil array coil for orbital apex, chiasm and intracranial optic pathways.
  • Immobilization straps and foam pads
  • Ear plugs

Patient Position

The is supine on the examination couch. The scan of the orbits are usually examined at the same time. Used of surface coil are placed over each orbit but should not touch the patient. Special holders are frequently provided by the manufacturers to enable the coils to be placed anteriorly over the eyes. When placing this coils ensure that the receiving side of the coils faces the orbits towards the table. The patient assumes a fixed gaze, straight ahead, with the eyes open. This enable the patient to focus and keeps the eyes still, thereby reducing motion artifact. Any eye make-up is removed prior to the examination as this causes image artifact and patient discomfort, especially if it contains metal.
Midline of the patient is positioned so that the longitudinal alignment light lies in the midline, and the horizontal alignment light passes through the orbits. If surface coils are used this corresponds to the center of the coils. Straps and foam pads are used for immobilization.

Suggested Protocol Orbits or Eye MRI
eye mri
FSE T2 of the orbits clearly
demonstrating the lens of the
eye, the globe, the optic nerves
and the chiasm.

Sagittal SE / FSE T1

In this scan, the top of the head to the foramen magnum is included on the image, and a medium slices or gap are prescribed on either side of the longitudinal alignment light through the whole head.
Left is 37 mm to Right at 37 mm.

Axial Oblique SE / FSE T1 or T2

A thin slices or gap or interleaved are made either in the true axial plane, or angled to the optic nerve from the inferior margin of the orbit to above the chiasm.

Coronal SE / FSE T2 or STIR

As for axial or oblique T1 except prescribe slices from the posterior border of the globe to the posterior aspect of the chiasm. Use chemical spectral pre-saturation on SE or FSE sequences
the slice 
orbit mri
Sagittal SE T1
weighted slice through the orbit
showing slice prescription
boundaries and orientation for
axial/oblique imaging of the
orbits and optic nerve.

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