CT vs HDVI

Technician monitoring a patient on the new machine.

The team at Sunstone Veterinary Specialists is very excited to let the community know about a new piece of advanced imaging equipment we have acquired. CT or ‘cat’ scan is a well-known method of advanced medical imaging that allows us to “look” through the body, map organs, tissues and sometimes observe abnormal structures. CT (Computed Tomography) in simple terms, is a series of tiny x-rays collected by a computer as the x-ray machine is spinning around the outside of a patient’s body. Each tiny x-ray is then added together through software to create a bread loaf-like slice of the area that has been scanned. The slices, which vary in thickness depending on the machine, are then “stitched together” by the computer blending and approximating the space between the slices. 

HDV (high-definition volumetric imaging) is a new technology that works similarly to traditional CT.  The difference between traditional CT and HDVI is that HDVI seamlessly circles the patient to collect true 3D imaging in 360-degree rotation vs. the ‘bread slices’ of a traditional CT.  Our HDVI, the Vimago GT30, acquires 720 images in a 6-inch section of the body as it circles the patient. It then brings them all together in a full 3D ‘box’ (called a voxel).  HDVI images are collected in as little as 24 seconds. These images are more refined than traditional CT because this technology does not rely on the computer to ‘guess’ at what is between the slices.  The voxel creates a complete image that is actual and not fabricated.  

Techs administering therapy on new machine.

Both traditional CT and HDVI require patients to be perfectly still on the table of the machine while this image is acquired (24 seconds with our machine) without motion artifact.  This means no waggling tails or twitching whiskers are allowed!  In dog and cat time, 24 seconds is an eternity and way too long to hold perfectly still.  I’m sure some people feel this way too! For this and other reasons, HDVI for pets does require anesthesia.  

Often, but not always, we will inject a dye or contrast material to aid in visualization.  Contrast is injected either through an IV catheter or directly into an area of interest (such as a knee), as part of an HDVI study. When used intravenously, the contrast goes through the veins, highlighting blood vessels of the body and emphasizing areas of concern. Disease processes often cause inflammation. Microscopically, inflammation causes dilation and expansion of the blood vessels. As contrast passes through blood vessels it will emphasize areas of swelling and disease process. Contrast can be irritating (it makes you feel warm all over) which is another reason for our patients to be under anesthesia and on IV fluids during this procedure. When using contrast in a study, we take one image prior to injecting contrast and a second image immediately after injecting the contrast. Both pre-contrast and post-contrast images are sent to the Radiologist to compare and aid in their evaluation of the HDVI images.

Vet technicians monitoring patient progress on machine.

Both traditional CT and HDVI are great ways to evaluate a body. However, looking at these images takes practice and specialized training. We will be sending your pet’s HDVI studies to a Veterinary Radiologist for evaluation. We have partnered with Peregrine Radiology, a group specifically trained in evaluating this new technology and these specialized images.

The goal of HDVI is to allow us to focus on specific areas of the body in much greater detail than x-ray or ultrasound. HDVI is not invasive. It does not cause any injury or impact to the tissue. 

Usually, HDVI will not be the first test we perform.  There are other non-invasive tests that do not require anesthesia that may just give us all the answers we need.  Also, HDVI does not replace x-rays or blood tests which give our veterinarians a lot of valuable information about your pet’s health. HDVI also does not replace our best test of all, which is a physical examination and consultation by a veterinarian.

Typical practical uses for HDVI in a Veterinary Specialty Center Include:

  • HDVI is often paired with other testing and sample collection.  For example, when paired with rhinoscopy, HDVI can give us a more complete picture of the sinuses prior to scoping and collecting tissue samples for lab evaluation.  
  • HDVI evaluation of the chest and lungs may reveal structures that are too small to be visible on x-rays. 
  • HDVI three-dimensional modeling gives our veterinarians a perfect image that can be viewed from any angle for evaluation of damaged, injured, or malformed joints.  These images improve pre-surgical planning. 
  • HDVI imaging allows for better surgical planning to correct liver shunts prior to entering the operating room.  Liver shunts are irregular blood vessels that can cause serious damage to the liver and body, often in young dogs and puppies. 

HDVI is an exciting new technology that we are excited to introduce to the Portland Metro area. HDVI creates a new level of detailed imaging for patients requiring more in-depth evaluation and treatment. We are excited to see how this can positively impact the lives of our canine and feline family members.