Various imaging techniques enable a veterinarian to view the internal organs and structures of a patient without performing exploratory surgery. These imaging techniques include computed tomography, endoscopy, magnetic resonance imaging, myelography, nuclear scintigraphy, radiography (x-rays), and ultrasonography.
Computed tomography (CT scan, or CAT scan) is used primarily for imaging the brain. It uses a sophisticated form of x-ray in which several x-rays simultaneously scan the body. This is used to diagnose brain and spinal cord disorders.
Endoscopy is commonly used to evaluate the inside of the digestive system. It is useful for diagnosing disorders such as stomach ulcers. Different forms of endoscopy evaluate different areas of the body including the nasal cavity, joints, bladder, and abdomen.
Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to show fine detail in the body. It is useful for soft tissue such as the internal organs and spinal cord.
Myelography uses dye injected into the spinal canal to visualize very small changes in the spinal cord. It is useful to pinpoint exactly where an injury occurred.
Nuclear Scintigraphy involves injecting radioactive compounds which travel through the bloodstream to target organs such as bones, thyroid gland, liver, etc. The function and health of the organ can be assessed by measuring the amount of radiation coming from the organ.
Radiography (x-rays) is very helpful in displaying different tissue densities. This is how disorders such as broken bones, pneumonia, or swallowed foreign bodies can be found. Sometimes, contrast medium (dyes) are used in combination with x-rays for further differentiation of tissues.
Ultrasonography (ultrasound) is a 'real time' study. It generates still or moving pictures from high-frequency sound waves. It shows the tissue in action - such as the heart beating. Ultrasound is useful in guiding the needle when a biopsy is necessary of internal organs such as the liver.
Multiple types of imaging may be needed to diagnose specific problems. For example, if a pet suffered an injury to the spine, survey radiographs would be the quickest and least expensive way of assessing the spinal column (bones) for obvious fractures and displacements. Computed tomography would be an excellent study for detecting small fractures missed on the survey radiographs. MRI and/or myelography would be useful in imaging the spinal cord (nerves).
As you can see, these newer imaging techniques enable the veterinarian to make more accurate diagnoses and more specifically tailor the treatment for the disease or condition. As a result, our pets can live longer and healthier lives.