Video guides to veterinary CT scanning - the spine

Computed Tomography (CT) is a useful diagnostic imaging modality that can provide you with more detailed information than conventional x-rays. Knowing when to do a CT scan (i.e. which types of cases and when in the case work-up) is crucial information. It helps vets get the most out of this modality for both the patient and the owner. However, there are also some considerations and limitations to think about. 

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Watch our short video guides which walk you through the key considerations for:

The videos cover:

  • what to consider before you choose to do a CT scan
  • CT vs x-ray for each body area
  • the limitations of CT scans. 

Veterinary CT scanning - questions to ask yourself

You can ask yourself these questions when deciding whether to choose to recommend a CT scan for your patient, or not:

  • is CT appropriate for the anatomy that I want to image? 
  • will it answer the clinical question that I have in mind, considering the presentation of the patient?
  • is it cost effective for the client, or would an alternative modality provide the answer at a lower cost? 
  • are there any contraindications that I need to consider before using it? This may be that the patient is not stable enough for chemical restraint (sedation or anaesthesia)
  • am I happy with my decision on which body parts to scan?
  • what type of acquisitions do I need to perform? 

Advantages and disadvantages of CT scanning

Irrespective of the anatomical region imaged, it's important to consider the advantages and disadvantages of CT in general. There are a good number of advantages including:

  • excellent spatial and contrast resolution
  • the ability to generate a 3D representation of 3D anatomy
  • ability to get a good overview of a large body area in detail
  • ability to give contrast to get information about vasculature and perfusion.

But there are also some disadvantages, for example:

  • it requires heavy sedation or general anaesthesia
  • it can be expensive
  • there are occupational safety considerations, such as ionising radiation
  • it may necessitate travel to a different location with a CT machine.
  • additional expertise in reporting the images is often required.

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Watch our short video guides which walk you through the key considerations for:

Veterinary CT for the spine

When could you choose CT for imaging the spine? Sometimes, if a lesion is primarily related to the spinal cord, for example a myelopathy, then MRI is preferable and recommended. But that is only where practical and available. There are plenty of other reasons why you might choose to do spinal radiographs or spinal CT first. 

Indications for spinal CT imaging include:

  • trauma
  • spinal pain
  • the presence of tetra-para/paresis, or even plegia, where MRI may not be available
  • any hind limb lameness is not attributable to orthopaedic disease, again, where MRI is not available
  • any characterisation and confirmation of vertebral lesions seen on radiographs.

It's important to remember the limitations of spinal CT. There are many aetiologies causing acute and chronic myelopathies that may not be seen on CT, and therefore, if you can't see them, you can't make a specific diagnosis, and so you can't make an appropriate management plan for that patient.

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Watch our short video guides which walk you through the key considerations for:

Understanding the CT Imaging Process

Performing a CT scan involves three main steps: acquisition, processing, and viewing. Each of these stages is distinct and critical for producing accurate diagnostic results:

  1. Acquisition: This step occurs in the CT room and involves positioning the patient and setting parameters such as KV, mAs, and table speed. It is important to optimise these settings because errors at this stage cannot be corrected later. It is also important to ensure pre- and post-contrast series are obtained where needed. During acquisition, raw data is collected as a vast set of binary data that needs further processing to be translated into interpretable images.
  2. Processing: This step transforms the raw data into images using the CT scanner's built-in computer. This can be done after the patient has left, provided the raw data is available on the machine. Processing parameters include slice thickness, filters, and display field of view (DFOV). Common errors in processing can be corrected as long as the raw data is intact.
  3. Viewing: This involves manipulating the processed images on a workstation using various windowing techniques to highlight different anatomical features. Windowing adjusts the image contrast and brightness to make different tissues more visible.

Want to know more?

Watch our short video guides which walk you through the key considerations for:

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