July 7, 2018: I am refreshing the series of blogs for CT in Veterinary Medical with updated information. -RW
Considering investing in a CT for your vet practice? Read this first.
You’ve probably already spoken to at least one sales person who has promised you the moon, and you’d like to trust that they have your best interests at heart. But how can you be sure that you’re investing in the right CT system that will help you round out your hospital’s imaging capabilities? You use ultrasound like a champ and your techs take fantastic digital radiographs. So…what about CT or Cone Beam CT? Purchasing one of these units is a lot more expensive than your ultrasound and your DR combined! You probably have more questions than a sales rep has good answers to.
What about asking a veterinary radiologist?
It is wise to seek good counsel from an experienced veterinary radiologist. I’ve talked to many veterinary radiologists about CT, and I’ve found two camps. The first is of the opinion that general practice veterinarians should avoid purchasing a CT, leaving specialty imaging to those who will “do it right” – which gets you high quality images that support accuracy of diagnosis. The second camp recommends CT as a good investment for a general practitioner. They believe that CT imaging in general practice, with proper staff training, continues the advancement of patient diagnostics at that level. In other words, a rising tide floats all boats.
A quick laugh about radiologists. A human radiologic technologist once told me that if you put 5 radiologists in a room and you will get 6 different opinions.
Investing in a CT scanner is no small decision
Before diving in, you must learn what CT is as a technology and what it is designed to be used for in veterinary applications. Not all CT machines are created equal in form and function. As stated in Part 1 of this blog, there are two types of CT technology available to veterinarians today, Spiral or Helical CT and Cone Beam CT. This post goes into detail about the differences between Spiral or Helical CT and Cone Beam CT.
What sales reps probably don’t know about Cone Beam CT (CBCT)
Why CBCT was developed
CBCT technology was originally developed for applications specific to human dentistry. These units are designed to produce high resolution cross-sectional exams of the human skull. The factory software in all CBCT machines can render the exam into a 3D model onscreen or into a more traditional stack of 2D images. This is really awesome. However, there are diagnostic limitations with 2D and 3D images from a CT scan of soft tissue organs in the abdomen. 3D images are of little diagnostic value to board-certified veterinary radiologists. Radiologists always rely on the 2D image stack in cross-sectional imaging modalities to report their findings.
So manufacturers of CBCT took a technology originally developed for human dentistry and adapted it for the veterinary market. This can be problematic if you plan to use the machine outside of dental applications in small animals.
Veterinary Medical Indications for Use of Cone Beam CT Technology:
Bone: skull fractures / nasal masses / dentistry / distal extremities / spine IVDD (requires contrast)
Soft Tissue: NO RECOMMENDED INDICATIONS ON MOST ANIMAL PATIENTS
The Science behind CBCT
CBCT emits a cone-shaped pattern of radiation, earning it the name “cone beam”. Essentially, a CBCT is a digital radiography system fitted onto a wheel inside of the familiar looking CT gantry. It contains a small flat panel detector (usually about 18cm x 16cm) and it is positioned perpendicular to a cone beam x-ray tube (like the tube in a conventional x-ray system). As the wheel with the components is moved 1 degree at a time around the target anatomy, a digital radiograph is acquired, and then it advances another 1 degree and takes another and so on, until it completes a full revolution around the animal patient. The data is then rendered by software into several different image data sets and transmitted to a PACS for storage and review.
Cone beam tubes produce a wide cone shaped signal pattern, originating at the tube (the point of the cone) and scattering outward toward the panel. This typically produces more scatter and thus there is less detail in soft tissue images when compared to spiral / helical CT modalities.
This is especially problematic in animals over 20 lbs., or in animals that are much larger than a human skull.
Can CBCT be a good tool for a veterinary hospital?
The hardware and software of CBCT units were optimized to acquire high resolution images of the human skull and particularly, the human mandible and maxillary portions of the skull. This means that it can definitely be a good tool for veterinarians who are passionate about canine and feline dentistry. Some veterinarians would be very interested in acquiring high resolution images of the patient’s skull which is crucial for quality performance of veterinary dental procedures such as extractions and reconstructive surgery.
The CBCT can also be used successfully for studies in the spine (IVDD with the use of proper positioning, collimation, and contrast). CBCT is also good when evaluating the integrity of joints and extremities (ex. canine elbow disease and osteosarcomas).
If the CBCT user can be trained to operate the technology within these limited indications, it can be diagnostically useful to a veterinary hospital, yet it will remain limited as compared to the spiral CT technology.
Some shortcomings of CBCT
- CBCT units were not designed to perform scans of the thorax or abdomen on human or animal patients.
- Most CBCT manufacturers’ machines do not allow cranial to caudal movement of the patient. The table or couch does not move automatically. This means that operators need to move the table or move the patient if the targeted anatomy does not fit within the finite field of view. Essentially, the CBCT unit remains stationary over the targeted anatomy and the field of view is limited to the finite dimensions of the selected capture area (L x W x D) in the acquisition software. This results in more than one series of images which will need to be either stitched together into a single stack of images or organized separately as individual image stacks. This can often frustrate a veterinary radiologist when reading a Cone Beam CT case that does not utilize automated and precise movement of the patient on the couch during the scanning process. When attempting to image the spine with CBCT, this can be a challenge for the operator to perform and for the radiologist to read.
- CBCT scans can also take more time to complete. If the thorax / lung fields were to be the targeted anatomy; as animals breathe and the heart beats distortions are produced from the motion within the chest cavity during the scan. A manually induced breath-hold (while under full anesthesia), can reduce the effects of “motion artifact” from the lungs but the heart continues to beat so motion artifact remains problematic if the heart is what is targeted. In the animal patient, the most precise evaluation of the heart should be performed with ultrasound (i.e. an echocardiogram) and thoracic radiographs.
4 Slice CT Lungs CBCT Lungs
Note: the entire lung field is captured by the CT. The CBCT leaves out some of the lung field due to its confined field of view. Lung views in the CT image stack are much higher in resolution. In the CBCT image, there are too many artifacts, and in this case an incomplete field of view for a radiologist to read it successfully.
CBCT Abdomen 4 Slice CT Abdomen
Veterinary Radiologists and CBCT
In general, all boarded veterinary radiologists are familiar with spiral CT as it has been around in veterinary specialty clinics for a couple of decades. However, most, but not all veterinary radiologists have done little or no research on the cone beam CT technology. Therefore, most veterinary radiologists will have a negative opinion about cone beam CT simply because they know very little about it and how it’s meant to be properly used.
The CBCT folks claim their technology produces less exposure to radiation for patients and operators. They argue that lead-lined walls are not required. Depending on various state regulations, this claim may be true. The accuracy of such statements are at the mercy of the local regulations of the end user. In addition to that, we are simply comparing apples to oranges when comparing CBCT to CT. Remember, the core design of CBCT technology is limited in application to the skull or extremities. These anatomy indeed require less radiation for acquisition of diagnostic images. However, in reality, it is not much less radiation than what a spiral CT uses to acquire diagnostic images on the same anatomy.
In my opinion, it is always better to err on the side of safety. Go ahead and design your CT room with lead-lined sheetrock and place the acquisition workstation outside of the CT room behind a lead-infused glass barrier where your technologist can see the patient and the attending technician. Yes, this costs more money up front but it can save a practice from safety citations and lower the potential for employee / client litigation in the long run.
Can a veterinary hospital be successful with CBCT?
The short answer is yes. The CBCT can be applied successfully in animal hospitals that perform a high volume of dentistry cases, and can be used effectively with imaging extremities as well as IVDD.
Computed Tomography Training for Veterinary Teams
CBCT and CT are not easy modalities to add in a veterinary hospital environment. Floor plan and power are not the only challenges we face either. The proper amount of training and the proper types of training are what make CT the greatest challenge of all imaging modalities. Even ultrasound (which requires copious amounts of personnel training) is actually easier to integrate into a vet practice than CT is. The bummer is that most vendors who are selling CBCT and CT to veterinarians are doing minimal training with their buyers.
The good news: Veterinary Intelligence (www.vetxq.com), has developed a formal CT training program specifically for veterinarians and veterinary technicians. We will have a team of veterinary CT technologists and board-certified veterinary radiologists who teach our clients all that they need to know about CT procedures in a general veterinary practice.
PRO: Perfect for small animal dentistry applications. Good image quality in canine and feline skulls as well as distal extremities.
PRO: Always sold brand new. Cost $175k – $250k depending on the vendor. 5-year warranty and service programs are offered with the purchase of CBCT from most vendors.
CON: Soft tissue image detail in the abdomen and thorax of animal patients is inferior to those generated by spiral CT.
CON: Field of View. A finite field of view on most CBCT machines can cause increased operator errors during acquisition. Most CBCT units do not move the patient or move through the patient cranial to caudal (automatically) which requires the manual movement of the patient by the operator and this produces multiple image stacks.
CON: Training. Most vendors do not offer a comprehensive training program for vet techs and veterinarians. Most invest a few hours to teach the client basic operation with safety training after installation. This is problematic because the client is left to learn more valuable lessons by trial and error.
CON: Radiologist review and reporting. Most boarded veterinary radiologists will refuse to read and report on CBCT cases from veterinary hospitals. Only a select few are willing to read CBCT cases. VitalRads.com is one of the few veterinary teleradiology services that read veterinary Cone Beam CT exams.
What you need to know about Spiral CT (CT)
Spiral or helical computed tomography equipment is specifically designed for cross-sectional scans of soft tissue and bone in human patients. The CT couch or table slowly moves the patient through the spiraling signal. One newer CT design has a mobilized gantry that uses a motorized wheel system underneath to “crawl” over the table or couch where the patient is positioned.
An acquisition workstation and software render the acquired dataset and organize the data into one or more readable exams based on selected anatomy and protocol.
So this is also a technology that was adapted for veterinary from human medicine.
Veterinary Medical Indications for CT Scans
Soft Tissue: met checks / mass ID / lungs / liver / spleen / GI tract / urinary tract
Bone: skull fractures / nasal masses / dentistry / distal extremities / complete spine / hips / pelvis
The fundamental technology consists of a specially designed x-ray tube that emits a confined linear beam of photons which pass through the patient that is received by a linear array of sensors as the scanning unit it continuously spins around the patient at high speed.
What’s the deal with CT and the number of “slices”?
You may have overheard a conversation about CT where someone refers to the number of “slices” their particular CT has. This is because the higher the number of “slices”, the better the image quality. Ultimately, image quality in a CT is determined by the number of channels (aka slices) available in the sensor array. Please note that “slices” is a misnomer that is essentially ‘medical slang’ referring to the number of channels in the CT’s sensor array.
The more channels a CT sensor array has, the faster it can scan a patient, raw data acquisition also increases and then is processed into higher resolution images. The more raw data that acquired, the clearer the image quality. A 40 slice CT system can perform a full body scan on a 90 pound Labrador retriever in less than 15 seconds and still produce impeccable image quality. This occurs when the operator (aka technologist) is experienced and well-trained in applications and protocols for small animal veterinary medicine.
Just like all software based technology, CT acquisition software applications have improved immensely over the last ten years. Most modern CT units (manufactured after 2012) will have highly-advanced acquisition software which allows a fully trained technologist to set up customized protocols which is great for applications in animal patients. CT units come from the factory with human presets (scanning protocols) in the software which means that it is up to the veterinarian and the CT technologist to adjust those protocols and customize their own presets for animal patients of various sizes and anatomy.
Some shortcomings of CT
- They can cost a lot. Brand new CT units can easily cost a veterinary clinic well over $600k which is often more expensive than the real estate the vet hospital sits on. Purchasing a new or refurbished CT scanner can reduce the investment to below $250k for the equipment purchase. Then you need to add the service and warranty contract after the first year is over. There are older, refurbished, 4 slice CT machines available for sale that cost less than $90k (before you add facility modification, training costs, and extended service agreements). A good rule of thumb is to buy refurbished, buy a well-known brand (GE, Philips, Siemens, Toshiba), and stay between 4 and 16 slices. Always purchase the preventive maintenance package with an extended warranty on the CT x-ray tube.
- They are big. Most of the refurbished spiral CT units are huge by comparison to the brand new CBCT units. Spiral CT rooms need to be at least 15’ x 15’ when developing the room’s floor plan. All of the CBCT units I know of can exist in a 12’ x 12’ sized room.
Veterinary Radiologists and CT
In general, all boarded veterinary radiologists are familiar with spiral CT as they each were trained on how to read CT images from spiral CT units. You should have no problem finding a boarded radiologist to read your CT scans from a spiral CT.
If a vet hospital can maximize the use of a CT, it is a good investment to go with a spiral CT because it’s simply more versatile. Radiologists are more open to reading CT scans. They do take up more room but a spiral CT makes more sense for most general veterinary practices.
Can a veterinary hospital successfully use CT?
Absolutely yes. CT can be used successfully in animal hospitals who are looking to up their game on imaging and who want to raise the level of practice inside their clinic walls. However, CT is not an easy technology to add to a veterinary hospital. It requires a new level of thinking about when and how imaging is ordered for animal patients. It requires specific training for veterinarians and technicians.
PRO: Versatility. Spiral CT has a broader set of applications than CBCT.
PRO: Reads. All veterinary radiologists are trained and prepared to read CT studies.
PRO: Clarity: Spiral CT is faster, so the “motion artifact” problem is greatly reduced vs. CBCT
PRO: Easy: Spiral CTs come with pre-programmed protocols and can be manually programmed with protocols that your hospital uses frequently. This makes image capture faster and more consistent.
CON: Cost. Higher resolution means better, more diagnostic images, but it also means a higher price tag.
CON: Space. The room size for a spiral CT is greater than the space required for CBCT.
How does this information help my decision?
Decide what’s important to you! You want to improve your vet hospital’s ability to get great images. CT is a good way to go if you already have an active ultrasound modality and use your DR system to its fullest capacity.
If cost is a major consideration, you will want to consider how to start making your investment back as quickly as possible. That may mean getting some great training with experts in veterinary CT. Look for a full discussion about ROI on CT in an upcoming blog.
If space is a major consideration, that will play into your decision. If you are landlocked in a strip center or your imaging suite simply cannot expand beyond its current footprint, look carefully at the space required for each. We can help you design a new hospital or add on to your new one. See our website: https://vetxq.com/consulting/
What is the culture in your veterinary practice?
Look at your culture and how you practice vet medicine. Maybe you don’t need a CT. You may not know if it will fit into your culture (i.e. your team’s collective philosophy of how you practice vet medicine). That is okay. It is imperative that you know your practice culture.
Part 2 has been aimed at the comparison of Cone Beam CT and traditional Helical or Spiral CT. Please contact me by email with any questions and please take some time to visit our website http://www.vetxq.com.
Robert Whitaker’s Email: firstname.lastname@example.org