GatorVet Imaging
Frequently Asked Questions
- What is Magnetic Resonance Imaging (MRI)?
- How does MRI work?
- What is Computed Tomography (CT or CAT-scan)?
- How does CT work?
- What are common applications of MRI and CT in small animals?
- What are common applications of MRI and CT in horses?
- Veterinarian: What is the appointment process?
- Pet Owner: How do I arrange an appointment?
- Pet Owner: What can I expect when I bring my animal for GatorVetImaging services?
- Are there any risks associated with MRI or CT?
What is Magnetic Resonance Imaging (MRI)?
Magnetic resonance imaging (MR) is a highly technical imaging test that involves the use of a strong magnetic field and radiofrequency (RF) waves to alter the behavior of atomic components in the body in a predictable and useful manner. MRI has become the standard in advanced imaging of many structural and functional abnormalities in small companion animals and in horses. It is highly effective in the diagnosis of many internal medical problems and in planning surgery of the central nervous system and other areas of the body. UF's Veterinary Medical Center, through which GatorVetImaging operates, has the only high-field strength (greater than 1.0 Tesla) MR unit in Florida and allows highly detailed images to be obtained in multiple planes of bone and soft tissue in all species.
MRI yields images with unparalleled tissue contrast and anatomic definition, and can provide physiologic as well as anatomic information -- a tremendous benefit in the early detection of many conditions. Timely intervention is then possible, thus improving the prognosis and long-term outcome.
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How does MRI work?
When a patient is put in a strong magnet, hydrogen protons in the body become aligned with the magnetic field. If a carefully tuned radio-frequency (RF) pulse is sent into the patient, alignment of the hydrogen protons is altered in a predictable fashion. Once the RF pulse is removed, the protons realign themselves with the magnetic field, and generate a current, or signal, in a receiver coil that is placed around the patient. The strength of the signal is dependent on the environment (chemical bonds, proximity of other magnetic components) of the protons. Through a complex mathematical equation (Fourier Transform), the location of each signal can be calculated, and displayed on a monitor for review by a radiologist.
Changes in the expected strength of a signal (signal intensity) are noted in cases where disease exists allowing the radiologist to make a diagnosis.
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What is Computed Tomography (CT or CAT-scan)?
Computed Tomography (CT) was introduced in the early 1970's and is one of the most common cross-sectional imaging modalities in use today. In CT, very fine x-ray beams are sent through the body to detectors that are located in a circular array around the patient. This data is sent to a computer which quickly processes the information and reconstructs an image. Essentially, CT images are reconstructed from hundreds of thousands of different radiographic projections.
The tissue images that show up on the monitor consist of white, black, and shades of gray, called the gray scale. The amount of gray shown indicates the ability of the tissue to absorb or transmit (attenuate) the x-ray beam. Manipulation of the gray scale allows better differentiation of tissue type and increased ability to detect lesions over conventional radiography. Changes in the expected attenuation of the x-ray beam may indicate a disease process.
Positive contrast media (dye) can also be injected into the patient's bloodstream to further increase tissue differentiation and aid in the diagnosis of disease.
Over the last decade, the introduction of multi-detector row computed tomography (MDCT) has increased the speed and sensitivity of CT, yielding images with much greater contrast resolution and spatial resolution and allowing studies to be performed in a matter of seconds.
How does CT work?
CT units produce a very thin fan of x-rays which are directed through the patient and strike rows of radiation detectors placed in a circle around the prone patient. The amount of radiation going through a specific part of the patient, and therefore reaching the detector is related to the density of the body part. A CT scanner takes numerous views of each part, and reconstructs an image using a complex system of equations requiring hundreds of thousands of calculations per second.
What are common applications of MRI and CT in small animals?
In small animals, both MRI and CT techniques are routinely applied to neurologic, oncologic and orthopedic cases at the VMC, with additional studies performed for radiation planning and metastasis evaluations. MRI and CT are not mutually exclusive technologies and should be selected based on respective advantages, purpose and cost.
Common applications of MRI in small animals include:
- Neural tissue disorders: brain, spinal cord, peripheral nerves
The superior contrast resolution of MRI makes it the best non-invasive imaging modality for evaluation of the nervous system. - Musculoskeletal disorders
MRI can be used not only to examine bony structures, but also to evaluate muscles, tendons and ligaments. In these applications, MRI is superior to all other imaging modalities. - Soft tissue tumors, abscesses, draining tracts
MRI is excellent in evaluating extent and margins of soft tissue lesions. In the case of chronic wounds and draining tracts, it can help identifying foreign bodies within the wound. MRI allows for the evaluation of bone involvement, assessment of lesion resectability and also for the diagnosis of regional lymph node enlargement. - 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. - Thoracic and abdominal disorders
MRI complements other imaging modalities when evaluating patients with thoracic and abdominal disorders. Screening for enlarged lymph nodes, evaluation of thoracic or abdominal wall mass lesions and diagnosis of abdominal organ parenchymal lesions are only few examples of indications for thoracic or abdominal MRI examinations.
Common applications of CT in small animals include:
- Nasal disorders: CT is useful in the evaluation of nasal disease, and allows for the detection of bone and brain involvement.
- Ear disease: Evaluations of the tympanic bullae and ear canals are quickly and easily performed using CT. However, if nerve or brain involvement is suspected, MRI provides more detailed information.
- Thorax and abdomen: Thoracic disorders, including metastatic neoplasia, mediastinal masses, and vascular disease (PTE, peripheral stenosis) are best imaged using CT. Similarly, evaluation and localization of abdominal masses, vascular anomalies, and metastatic neoplasia is quickly and accurately performed and may allow for sampling of abnormal tissue.
- Musculoskeletal disorders: CT is commonly used for evaluation of complex fractures and for surgical planning in cases of angular limb deformities.
What are common applications of MRI and CT in horses?
MRI and CT provide an early link to the diagnosis of injuries or disease in horses. Both modalities have provided practitioners with new avenues to better diagnose a variety of disease conditions in horses before the disease process takes hold, causing potentially life-threatening complications. MRI and CT are not mutually exclusive technologies and should be selected based on respective advantages, purpose and cost.
Common applications of MRI in horses include:
- Foot, fetlock, suspensory joints, carpus, hock and heads are regions capable of being examined through MR in the horse.
- MR allows highly detailed images to be obtained in multiple planes of bone and soft tissue, and the use of MRI can help determine specific causes of lameness. This is extremely important, because an accurate diagnosis of the horse's problem allows appropriate treatment recommendations to be made.
- An MRI examination is indicated when the results of other imaging techniques do not yield a diagnosis. MRI also can be useful when the diagnosis is known but the extent of injury is difficult to determine, such as in some cases involving puncture wounds or navicular bone degeneration.
- MRI examination is also useful in the diagnosis of neurologic disease localized to the brain.
- The exceptional contrast resolution of MRI makes it an excellent tool in the evaluation of horses with evidence of sinonasal and tooth root disease.
Common applications of CT in horses include:
- Spiral CT may be used for fracture evaluation and repair planning. 3-dimensional reconstruction is exceptionally useful in fracture repair planning.
- CT also is valuable for imaging the skull and teeth of horses, and is especially usefull in the diagnosis of sinonasal disease.
Veterinarian: What is the appointment process?
Please refer to the forms link on the GatorVetImaging home page for detailed information. All forms must be completed and submitted to our GatorVetImaging Liaisons before you or your client can schedule an appointment. If you have any questions, please call us at (352) 273-8585.
Pet owner: How do I set up an appointment for my pet?
Once your veterinarian has completed and submitted the necessary forms to us, your veterinarian will be contacted and an appointment will be made. No scheduling will take place until all forms have been obtained. Your appointment will be made by your veterinarian.
Pet owner: What can I expect when I bring my animal for GatorVetImaging services?
On the day of your appointment, you will meet with the veterinary clinician who will receive and admit your pet or horse. Drs. Amy Stone or Julia Wuerz will serve as the point of contact for small animal clients; Drs. Matt Brokken or Ali Morton will serve this role for equine patients.
This clinician will outline the imaging service goals for your pet and will ensure that the necessary information and history have been obtained.
A general physical examination will be performed and immediately afterwards the animal will be transported into the GatorVetImaging pre-anesthesia holding area.
- Large animal patients will be admitted to UF the day prior to the procedure and will be discharged the day following the procedure.
- Small animals will be admitted and discharged the same day.
- Upon discharge, you will receive a folder containing copies of essential paperwork and a CD of all images obtained through GatorVetImaging.
- Within 48 hours, the veterinarian will receive a report from one of our veterinary radiologists summarizing findings from the imaging study.
Are there any risks associated with MRI and CT?
MRI and CT are both considered extremely safe imaging modalities.
MRI uses radio-frequency energy to excite molecules in your pet -- similar to that which a radio or TV station emits. No ionizing radiation is used. Low magnetic fields have not been demonstrated to be harmful to animals or people. Caution must be taken in animals or people that have been implanted with pacemakers or metal clips in certain areas. Because pets cannot move during the MRI scan, they must be anesthetized during the procedure. While there are some risks inherent to anesthesia, at UF VMC, anesthesia is supervised by board-certified anesthesiology specialists who carefully assess each patient prior to the procedure.
While CT scanning uses ionizing radiation, the dose received by the patient is similar to that of conventional radiographs (X-rays) and less than that for a human receiving a similar procedure. CT should be avoided in breeding animals during the first trimester of pregnancy. Pets are usually anesthetized for CT scans. These procedures are relatively quick (15 - 30 minutes), further minimizing the risks.