Diagnostic Imaging
Diagnostic Imaging describes the techniques available to visualise the inside of the body and is central to many, if not all, of the cases that we will see.
There are different imaging modalities available, depending on the disease process. These include:
Radiography
At Granta Veterinary Specialists, we have digital radiography to obtain excellent radiographic (X-ray) images of the body, giving us a quick and budget-friendly assessment of the chest and abdomen. The patient sits or lies down on a special table situated below the X-radiography machine and it takes around 0.2 seconds for the machine to work. Radiography is also very useful in trauma situations to quickly assess systems, e.g. traumatic thoracic injury.
Ultrasound
This modality uses high-frequency sound waves, similar to a ship’s sonar system. The ultrasound machine passes very high-frequency sound waves into the patient and listens for the echo. By measuring the time it takes for the echo to come back and the strength of the echo, it can tell the difference between different tissues and the image is formed.
Ultrasound is useful for soft tissues and is particularly good for abdominal organs, lymph node localisation and assessment of heart size and function. Ultrasound is completely safe in every patient, but it has limitations in that it cannot “see” through bone or air, unlike all of the other modalities described. Ultrasound is operator-dependent, and we will be utilising a team of specialist imagers to ensure we obtain the maximum amount of information from a scan. Ultrasound can also be used in an emergency situation to scan for fluid or air in body cavities e.g. BD foreign body.
CT (Computed tomography)
Computed tomography is basically a large radiography (X-ray) machine that spins quickly through 360 degrees around the patient taking radiographic images from different angles as it spins. Through this we obtain much more detailed images than we can with routine radiographs, and have the ability to reconstruct 3D images. CT is excellent for the chest, many soft tissues and bones. It is fast to perform and the use of contrast agents increases the detection of tumours or areas of inflammation e.g. nasopharyngeal cyst.
At Granta Veterinary Specialists, we have one of the most modern and sophisticated CT scanners currently available – the 64 slice Phillips Incisive with technology to improve patient positioning accuracy, image quality and enhance contrast. This is a frontline CT scanner used in many human hospitals around the world.
MRI (magnetic resonance imaging)
This uses magnetic coils and radio frequency waves to image the body. MRI provides us with exquisite detail of soft tissue structures (e.g. flank abscesses), especially of the brain and spinal cord. We will have access to an MRI scanner on site to assist particularly with neurology and oncology cases initially via a visiting MRI service but we will be investing in a “1.5 Tesla zero-helium” scanner, again made by Philips. MRI scans are extremely safe for the patient, but metal plates or implants (such as pins or plates for a fracture repair or a pacemaker) can interact with MRI so it is vital we know this before we do the scan.
Endoscopy
In some cases, visualisation of organs, such of the bladder, colon, ear, nose or trachea, can be gained by using endoscopes (small cameras on tubes), which are either rigid or flexible. If we use endoscopy we can also take small samples of any tissue we are concerned about, remove obstructive tissue or sometimes remove foreign material (e.g. Laser assisted turbinectomy).
We will decide this on a case-by-case basis, depending on the likely disease present, the area of the body we are concerned about and the requirement for sedation or general anaesthesia. Sometimes we use more than one imaging modality, e.g. detecting affected lymph nodes on CT and then sampling them with the help of ultrasound.
This will be the most likely scenario. Sometimes we will need to schedule a second appointment so that blood samples or other diagnostic tests are back before we image your pet so we can be confident that we are imaging the right part of the body. If your dog has a condition that we see commonly, we may schedule imaging at the same appointment as surgery.
Some imaging modalities, such as ultrasound, are best performed by a veterinarian trained in veterinary diagnostic imaging and is a Specialist. Other modalities, such as radiographs, just require review by a veterinary diagnostic imager. We will work closely with our imaging team to ensure we use the best techniques for your animal.
This depends on each case. Often it is preferable to have a gap between the imaging and the surgery so that the images can be thoroughly reviewed before any further procedures and to allow an appropriate plan to be made and discussed with you. In some cases, we may feel it is appropriate to continue to treatment after imaging.
In most cases, depending on the procedure, your pet will be able to go home after imaging. If your pet is scheduled for surgery the following day or has had a contrast agent to improve the imaging, we may keep them overnight.