Video Guides to Veterinary CT Scanning - Musculoskeletal System

Video guides to veterinary CT scanning - musculoskeletal system

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.

Want to know more?

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

• Head and neck CT scans
• Musculoskeletal CT scans
• Spine CT scans
• Thoracic CT scans
• Abdominal CT scans

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.

Want to know more?

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

• Head and neck CT scans
• Musculoskeletal CT scans
• Spine CT scans
• Thoracic CT scans
• Abdominal CT scans

Veterinary CT for the musculoskeletal system

When should you think about recommending CT for the musculoskeletal system? Due to its excellent spatial and resolution, it is used routinely now for elbows, shoulders and often for the carpi and tarsi. It is also incredibly helpful in providing diagnostic information in complex or atypical orthopaedic cases, for example a dog with a  chronic lameness of unknown cause, where a diagnosis wasn’t able to be made on routine radiographs.

There are many indications for musculoskeletal CT including:

• joint diseases - there are many different types of joint disease that can be accurately characterised on CT such as osteoarthritis, dysplasia and osteochondrosis
• angular limb deformities
• musculoskeletal neoplasia, both bone and soft tissue
• in trauma cases where there may be complex fractures or fracture luxations, particularly of awkwardly shaped bones
• appendicular swelling
• for surgical planning.
  

In addition, another use case for CT is when something has been spotted that could be an aggressive bone lesion on radiographs.  You might want to use CT to characterise this lesion or confirm an aggressive bone lesion, plus perform a CT of the thorax to stage the neoplasia.

Additionally, there may have been something seen on radiographs where it wasn’t clear whether it is significant or not, a subtle lesion. We might want to characterise or confirm whether that might be clinically significant. 

Want to know more?

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

• Head and neck CT scans
• Musculoskeletal CT scans
• Spine CT scans
• Thoracic CT scans
• Abdominal CT scans

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:

• Head and neck CT scans
• Musculoskeletal CT scans
• Spine CT scans
• Thoracic CT scans
• Abdominal CT scans