Diagnostic Imaging : MRI Scanning

A dog within the scanner during a MRIscan

Magnetic Resonance Imaging

Like CT scanning, MRI imaging provides cross sectional views of the internal structures of teh body. Whilst CT is very good for imaging bones and lungs, it is less satisfactory for soft tissue imaging. This is where MRI comes in.

MRI is very good at showing soft tissue architecture and detecting areas of abnormal tissue and inflammation. Like CT and radiography, MRI can be performed using a contrast medium to highlight areas of increased or reduced blood flow and inflammation.

Scans take a while to perform during which time the patient has to remain still, so anaesthesia is essential. Because there is no stimulation or pain associated with scanning, the level of anaesthesia only needs to be light, i.e. sleep rather than deep surgical anaesthesia.

MRI showing a cervical disc protrusion

Image reconstruction

The nature of CT and MRI scanning permits computer reconstruction of anatomy in multiple planes so from a single scan series it its possible to get images in 3 or more planes, the standard ones being axial:

horizontal:

and saggital:

The above images show a nasal tumour almost filling a dog's nose and extending down through its palate. Below are two images showing a brain tumour.

A brain tumour in a cat. This was surgically removed