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Nowadays, most patients, animal owners, doctors and veterinarians tend to take modern diagnostic imaging for granted. From our current perspective in the year 2022, it's almost impossible to imagine how little people really understood about the body's inner workings before the discovery of X-rays by in 1895. This revolutionary discovery would mark the dawn of a new era in medicine. The discovery wasn't followed by any new innovations until the 1970s, when diagnostic imaging underwent a sudden and rapid development. So which techniques do today's veterinarians use in their day-to-day work? Find out in the following three examples. 

Accurate diagnosis requires real skill. Veterinary students have received thorough training in this area since the start of the programme in 1822. Although clinical reasoning can go a long way, it can be hard to determine the true nature of the symptoms without imaging data. You could compare it to travelling without a map. After the discovery of X-rays in 1865, it would take more than half a century before the technique was actually applied in veterinary medicine. The first major turning point in diagnostic imaging would come years later, when the development of ultrasound made it possible to visualise soft tissue. CT, MRI and SPECT then made it possible to create cross sections of a body: an invaluable complement to the projections and shadow images captured by X-ray cameras. Rather than projecting images on top of each other, these techniques yield segments or slices that can be composited into three-dimensional reconstructions. Developments have since accelerated and radiology has become a specialised discipline at the Faculty of Veterinary Medicine. 

Cooperation with human medicine

Today, diagnostic imaging specialists at the ľ¹Ï¸£ÀûÓ°ÊÓ Animal Hospital work closely with other specialists in the fields of care, education and research. 'The thing is, that kind of teamwork with veterinary specialists from all disciplines is exactly what makes my work at the Faculty of Veterinary Medicine so interesting', explains Stefanie Veraa, radiologist and head of diagnostic imaging at the Faculty of Veterinary Medicine. 'Our collaboration with human medicine also offers exciting opportunities for translational human and veterinary medicine. That allows us to help both animals and people while taking veterinary medicine - and diagnostic imaging in particular - to a higher level.'

X-ray

Dynamic imaging 

X-ray technology is still highly relevant more than 70 years after its introduction at the faculty. The X-ray room features a range of ceiling mounted devices and a booth for horses. Diagnostic Imaging Team Leader Joris de Brouwer shows off the room, which was redesigned in 2020. An X-ray system moves along the overhead rails, guiding the X-ray tube to the exact part of the horse the radiographers want to examine. This multifunctional X-ray system can be used to perform static and dynamic imaging of both pets and horses. 'We used to have two separate rooms for that', De Brouwer explains.
'One for radiological examinations of horses and one for horizontal examinations of pets. The new system, which was specially tailored to our needs, combines both technologies in a single room. The room also features a custom-made transparent tank for the horizontal screening of dogs and other pets. The use of contrast agents allows us to visualise specific structures in the animal's body. De Brouwer: 'For example, we use this technique to do barium contrast swallow tests where the animal can stay upright. This allows us to assess the function of the oesophagus. We can also evaluate the movement of a dog's hip joint before and after surgical procedures, such as with 3D implants.'

The room and X-ray system must meet special requirements in order to allow for the examination of different-sized animals. 'Horses are obviously easily startled and they're large and heavy animals', De Brouwer explains. 'You can try all you want to make a horse stand in one place, but we ultimately have to move our X-ray tubes around the animal to get a good view of its body parts. That's why we work with this system, which is flexible and as quiet as it can possibly be. All the equipment is basically designed for use in human hospitals, so suppliers really have to think outside the box on our behalf. In a regular hospital, everything has to be as light as possible to fit into a small x-ray room.'

MRI and CT

 A comprehensive picture of back pain

'An X-ray is often all we need to examine osteoarthritis; we don't always need a CT or MRI scan', explains Marianna Tryfonidou, Professor of Regenerative Orthopaedics at the Faculty of Veterinary Medicine. 'However, back pain examinations do require both a CT scan and an MRI scan. Back pain can be caused by bone abnormalities, such as an ill-fitting sacrum. You can see that really clearly on a CT scan, so you know you'll have to operate to create space for the nerves. MRI scans allow you to visualise the nerve roots and the intervertebral discs. Combining the two examinations gives us a complete picture.'

Tryfonidou is researching back pain due to wear and tear of the intervertebral disc, the protective layer between the vertebrae. Back pain is a major problem in both humans and dogs. She is developing innovative treatments for dogs that will eventually help doctors treat people with back pain. 'We've had an MRI scanner at the ľ¹Ï¸£ÀûÓ°ÊÓ Veterinary Hospital since 1999', Tryfonidou explains. 'Our colleagues at UMC Utrecht are now taking things a step further with the bone MRI. This technique can be used to generate 3D images of both bone and soft tissue without any need for X-rays. It allows you to simultaneously visualise soft tissues and bone structures using magnetic radiation. We would love to develop the same technology so that we can fully examine back patients with a single imaging technique.'

Left: Tryfonidou injects a medication designed to treat dogs and - eventually - humans with back pain. This procedure is carried out under a CT scanner in order to determine the exact location. Image: Bas Niemans | Right: Laboratory technicians from the Utrecht ľ¹Ï¸£ÀûÓ°ÊÓ Veterinary Hospital make an X-ray of a horse's hind leg in the X-ray room, which was fully renovated in 2020. Image: Cojan van Toor

CT and SPECT

Revealing hidden structures

'The CT scanner is a crucial part of my work', explains Sara Galac, an endocrinologist and researcher at the Faculty of Veterinary Medicine. 'For example, a dog with pituitary tumours really needs to go through the CT scanner. Even if the dog won't be operated on or radiated, you still need to do a CT scan to assess its current and future quality of life. The Netherlands is really leading the field in that area. We absolutely need CT scanners to determine the size of the tumour and figure out its implications for the dog's wellbeing. Pituitary tumours are hidden in the skull and there's no other way to visualise them that clearly. Animal owners always respond gratefully, even if you have to give them bad news. A CT scan of the pituitary gland will give you insight into the animal's quality of life. If the dog does need surgery, the surgeon will need the CT scan to figure out the best way to remove the tumour. The CT images can also be used to plan the radiation treatment.

Galac is looking forward to seeing the SPECT/CT scanner arrive at the faculty. The device combines a gamma camera (nuclear diagnostics) with CT technology. 'The gamma camera we have been using until now produces coarse images with speckles, a bit like an impressionist painting. There isn't enough detail to operate with. The SPECT/CT scanner uses radioactive material to create more accurate images of things like adrenal medulla cells in the lower abdomen, chest, spinal cord and other areas where these cells tend to metastasise. That knowledge allows us to make diagnoses, offer the most appropriate treatment and set realistic expectations for the animal owner.

In addition to her work in patient care, Galac researches rare cancers in companion animals and cultivates organoids (mini-tumours produced from stem cells and cancerous cells) with her team. She hopes her work will help to advance oncological research in both animals and humans. For example, she hopes her research on adrenal gland tumours (pheochromocytoma) will eventually advance efforts to integrate diagnostics and therapy ('theragnostics'). A case in point would be the use of radioactive fluid by physician researchers in the diagnosis of tumours and potential metastases. Chemotherapy is then administered using the same method in order to treat the cancer.

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