Magnetic Resonance Imaging (MRI)

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In order to generate an image in an MRI machine, the animal is first placed in the centre of a very powerful magnetic field and then pulses of radio wave energy are directed at it. In response to these pulses of radio wave energy, each different body tissue emits a characteristic type of energy signal. A computer then uses these characteristic types of signal to produce a picture of the various tissues within the animal’s body along with their specific location. An animal must keep perfectly still during a study and so it therefore has to be anesthetized lightly.

We are fortunate to be able to use a state-of-the-art scanner at MRI Vancouver. With such a powerful magnet, potential contraindications to MRI include the presence of metal within the body, such as metal plates, gold bead implants or lead shot. Additional information on MRI is available under Neuroimaging.

Figure 19-1: Images from two dogs that underwent MRIs as part of a diagnostic evaluation for their seizure disorders. The spinal fluid (CSF) shows as white in these T2-weighted images. A: This dog had a normal MRI and was diagnosed with idiopathic epilepsy. B: This dog has a large, fluid filled extension of one lateral ventricle (arrowhead) along with mild atrophy of the brain on that side. The final diagnosis was that this dog had a congenital abnormality that it had probably been born with and that was likely to be the cause for its seizures.

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