Magnetic Resonance Imaging In Animals

What is MRI and how does it work?

Magnetic Resonance Imaging (MRI) uses a strong magnetic field to align the natural spinning of water molecules (protons) within the body tissues. MRI images are formed by radiofrequency signals generated as the nuclei of the protons spin. The molecular alignment that occurs on the sub microscopic level cannot be felt and has no known harmful effects. The radio-signals are collected by receiving coils placed outside the patient, near the area we try to image and evaluate. An advantage of MRI is its ability to produce images that are simple cross-sections, as well as from any other angle with equal resolution. MRI scans give the best soft tissue contrast of all the imaging modalities.

What are a few applications for MRI in Veterinary Medicine?

Neural tissue disorders - brain, spinal cord, peripheral nerves. MRI is the best modality to evaluate the nervous system. It is non-invasive and has the best contrast resolution of all imaging modalities. MRI can be used not only to examine bony structures; it is superior to all other imaging modalities when evaluating muscles, tendons and ligaments.

Soft tissue tumors, abscesses, draining tracts - MRI is excellent in evaluating extent and margins of soft tissue lesions. In case of chronic wounds and draining tracts, it will help identifying foreign bodies within the wound. It will allow evaluation of bone involvement, assessment of resectability of a lesion and diagnosis of regional lymph node enlargement. It proves very useful in diagnosing and staging cancerous growths and tumors.

Nasal/ paranasal sinus, orbital and ear disorders - MRI is very useful when evaluating patients with signs of nasal disease, disorders of the orbit and disorders of the ear. It is the modality of choice when extension of the disease process into the brain is suspected.

Other Indications & Symptoms for Diagnostic MRI

  • Cervical, Thoracolumbar or Lumbosacral Pain
  • Lameness & Ataxia, Tendon & Ligament Injuries
  • Paraparesis, Hemiparesis, Tetraparesis, Hypermetria / Dysmetria
  • Urinary Control & Defecation Difficulties
  • Non-Orthopedic Muscle Atrophy
  • Edema of Unknown Origin
  • Soft Tissue & Neurological Trauma
  • Seizures & Tremors, Head Tilt & Vestibular Symptoms
  • Nasal / Paranasal Sinus Diseases
  • Blindness, Anisocoria, Strabismus, or Horner's Symptoms
  • Facial Paralysis & Dysphagia
  • Hiding, Head Pressing, or other Behavioral Changes
  • Tumors & Oncology Issues

Frequently asked Questions:

How do I prepare my pet for their study?

It is best to prevent your pet from eating any solid food for 8-12 hours prior to their appointment. Water typically empties from the stomach within 15-30 minutes, so your pet should have access to water at home prior to their appointment. If your pet is currently on any medications, please ask your veterinarian if they should be given the morning of the scan. During the admission process, the Veterinary Imaging professionals will be happy to answer any additional questions you might have regarding the MRI.

What is the MRI Examination Process?

  1. Your pet will undergo a physical examination and have preanesthetic bloodwork performed by your veterinarian prior to you appointment. The MRI Outpatient Referral Form should be filled out by your veterinarian. If it is a neurology case, they will also need to complete the NeuroWebVet exam form. Both forms, bloodwork, and all pertinent medical history can be sent by fax (985-809-1591), emailed to SouthPawsVet@gmail.com, or you can bring them with you.
  2. An intravenous catheter will be placed in a leg vein for the administration of anesthetic agents. Note: Preparation for the catheter requires some hair clipping at the site.
  3. Your pet will then be moved to the MRI magnet room, positioned, and scanned while under anesthesia.
  4. After the MRI exam, your pet will be brought to a recovery room, where it will be allowed to wake up from anesthesia. Shortly thereafter your pet will be ready to go home.
  5. The MRI examination will be interpreted by a board-certified veterinary radiologist / neurologist. The written report will be sent to your referring veterinarian the next business day.
  6. The normal time for a MRI exam is 1 1/2 to 2hours. However, individual animals vary in their recovery time. You should plan on leaving your pet with us between 6-8 hours.

Contraindications

The main contraindication for MRI is the presence of certain metal implants (steel, pacemakers) in the patient. Animals with microchips may have MRI, although a microchip may cause local artifact. If metal is present in a patient close to the area of interest, artifacts might interfere with image interpretation. In very rare instances, a study might be non-diagnostic due to a metallic foreign body in the patient.

Why would my pet need an MRI?

MRI is performed most often to evaluate the brain and spinal cord when clinical signs indicate disease of the central nervous system is likely. MRI is also very good for looking at joints and other musculoskeletal diseases especially when soft tissues are suspected to be abnormal. MRI imaging is also ideal for cancer patients because of its utility in pre-surgical planning, treatment response with follow-up MRI scans and prognosis based on extent of disease.

Are there any risks associated with the MRI examination?

MRI is considered an extremely safe imaging modality. The examination is performed under general anesthesia. This is necessary to keep the animal from moving and minimize examination time. There is always a certain risk associated with anesthesia, which is not different when performing an MRI examination from other instances where anesthesia is required.

Does my pet have to go under anesthesia?

Typically, Yes, anesthesia is necessary for MR imaging, as the patient must stay perfectly still to acquire a good quality scan. Depending on your pet's medical condition, anesthesia and MR imaging may involve some risks. This will be discussed with you in detail during the admission process.

To ensure your pet's well-being:

Your family veterinarian will complete blood work and any other testing needed and submit results to us before we anesthetize your pet. This way, we can tailor our anesthetic plan specifically to your pet. Your pet will be closely monitored by an experienced veterinarian and veterinary technician before, during, and after the procedure. Your pet's heart rate, respiratory rate, blood oxygen concentration, and other parameters will be closely watched.

When will I get results?

A highly qualified board - certified veterinary radiologist with extensive experience in veterinary MRI will view and interpret the images of your pet, and the results will be reported to your veterinarian within 24-hours of the procedure.

Will the MRI affect my pet's behavior?

Pets are usually quiet and "wobbly" following general anesthesia. Don't be alarmed if your pet shows less interest in food the day of the procedure. Your pet should return to normal in one to two days. Pets may also experience a mild cough following anesthesia, due to the breathing tube used during the MRI procedure. This usually disappears after a few days. However, if you observe any unusual behavior, or have any concerns, you should always contact your veterinarian immediately.

How do I make an appointment?

Veterinary referrals are required to schedule an appointment.

Is MRI painful for my pet?

No. The MRI is painless. Some pets are uncomfortable because of other health problems. We will take great care in ensuring their comfort.

The Vet-MR adds one more advanced, non-invasive imaging modality to our hospital. It allows us to offer veterinarians, clients and their pets a higher standard of care.

Magnetic Resonance Imaging for the neurologist is what the ultrasound is for the internist and the echocardiogram is for the cardiologist. It has elevated the quality of care that we can provide for our patients.

Further Information

South Paws Outpatient MRI Imaging Process(pdf)

NeuroWebVet Examination Form (pdf)

South Paws Outpatient MRI Referral Form(pdf)

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