MRI scan of a dog (veterinary MRI) – indications, contraindications, preparation for the examination

Magnetic resonance imaging (MRI) is an advanced diagnostic technique that is becoming increasingly common in veterinary medicine. It is a non-invasive method that allows detailed imaging of the internal structures of animals, and its use in diagnosis is crucial in many cases. To provide some insight into this topic, in this article we will focus on basic issues related to indications, contraindications and preparation for MRI scans in dogs.

What does an animal MRI look like?

MRI is a safe and painless examination that uses the effect of a magnetic field on the hydrogen atoms present in the animal’s body. This field is generated by a magnet inside the MRI scanner, and the magnetic interaction causes the hydrogen atoms to emit energy in the form of radio waves at a specific frequency. A transmit/receive coil picks up this energy, and subsequently a computer converts the signal into an image. This produces images in different shades of grey in the coronal, sagittal, transverse and oblique planes. Compared with ultrasound, MRI allows better imaging of the brain, spinal cord, deeper structures of the musculoskeletal system and possible cancerous tumours.

How to prepare a pet for an MRI scan?

An MRI scan can be performed at a veterinary clinic that is equipped with a suitable scanner. The pet owner should also obtain a referral signed by a veterinarian. The examination usually takes several dozen minutes. It is a completely non-invasive and painless procedure, but the pet must remain still throughout the scan, which requires general anaesthesia. However, this anaesthesia does not need to be deep – only sedation is used to allow intubation (insertion of an endotracheal tube) and then inhalation anaesthesia is administered. This is the safest method of anaesthesia as it minimises stress on the animal’s internal organs (such as the kidneys and liver) and allows the animal to wake up quickly.

Preparation of an animal for an MRI scan includes:

  • a fasting period of 8–10 hours prior to the scan (no food but free access to water);
  • a clinical examination;
  • a basic blood test (to assess kidney and liver function);
  • a cardiac examination, such as an echocardiogram.

An MRI scan is completely safe for the patient, even if they have metal implants in their body. The only risk is prolonged anaesthesia, which lasts tens of minutes. The patient must remain absolutely still during the scan, as any movement will interfere with the diagnostic scan.

Advantages of MRI scans

The benefits of MRI scans include:

  1. high image resolution – MRI provides detailed images of soft tissues, allowing for accurate assessment of body structures such as the brain, spinal cord, joints, muscles, and internal organs;
  2. safety – MRI is safe because it does not use ionising radiation, which is used in X-rays and CT scans;
  3. multi-planar imaging – MRI can produce images in the coronal, sagittal, transverse and oblique planes, making it easier to accurately locate lesions in the body;
  4. accurate diagnosis of cancerous lesions – MRI is particularly useful in detecting tumours and assessing their size and structure;
  5. imaging of deep structures – the examination allows accurate imaging of structures such as the brain, spinal cord, ligaments, tendons and other musculoskeletal components, which is more difficult to achieve with ultrasound.

Indications for MRI in dogs

MRI imaging in dogs is primarily used to diagnose spinal and brain disorders, to examine soft tissues in the abdomen and pelvis, and to evaluate knee joints. The highest quality MRI scanners, such as the state-of-the-art equipment from United Imaging Healthcare, which can be tailored to the needs of the clinic, are used for detailed analysis and accurate identification of problems.

Contraindications to an MRI scan in a dog

MRI cannot be performed on animals with implanted life support devices that may be affected by magnetic fields, such as:

  • neurostimulators;
  • infusion pumps;
  • stents or vascular clips that react to the magnetic field;
  • magnetically sensitive components placed near the orbit or skull.

If the implanted components are approved as MRI safe, a certificate must be provided to the veterinarian. If a microchip is present in the area to be scanned, it must be removed beforehand.

*IMPORTANT! The information contained in this article is for informational purposes only and is not a substitute for professional veterinary advice. Each case should be evaluated individually by a veterinarian. Consult with your doctor before making any health decisions.