Computed tomography (CT)

CT stands for computed tomography and is essentially an X-ray procedure where the tube head rotates 360 degrees around the patient. The X-ray beam used in CT is very fine in contrast to the broad beam used in conventional radiography. As it passes through the patient a series of Image ‘slices’ (as thin as 1mm) are acquired in the transverse (axial) plane. These images can then be reconstructed in alternative planes (sagittal and dorsal) and in 3D.

Since it’s first introduction in 1972 CT has evolved and now provides an astonishingly rapid imaging modality of our patients that would have previously been unthinkable. CT machines are a wonderous mix of creativity and advanced technology. Now considered the most holistic imaging modality CT appears to be in a more innovative phase now than ever before.

Grove Referrals offers a fortnightly CT service provided by Burgess Diagnostics mobile unit. The majority of images can be interpreted in house, however on occasions we use VetCTspecialists to provide specialist reports. We are currently undergoing major re-development of our premises and facilities and are pleased to anounce the installation of an onsite 16 slice GE Brivo 385 CT scanner by the in February 2013.

Pets undergoing CT will stay at Grove Referrals for between 1 and 3 hours depending on the region or regions being examined and what other procedures are being carried out. The full procedure will be discussed with clients on arrival and they will be asked to sign a form of consent for this. All patients are given either a heavy sedative which can be reversed or a light anaesthetic which wears off very quickly. Which is used will be determined by the patient’s medical history and what is being done.

When complete the images will be reviewed and an interim report discussed with the client. Patients requiring further treatment will either remain at the Grove or an appointment scheduled for a future date. A full report will be available within 24-48 hrs as it takes a long time to go through all the images generated and to produce any reconstructions which may prove necessary.

Skeletal

CT allows clear definition of bone in general and especially so where superimposition of adjacent structures makes clear assessment difficult e.g. joints, and pelvis. Developmental elbow disease, hip dysplasia, cruciate disease, complex fractures, patella luxation, articular (joint) fractures, angular limb deformities and bone neoplasia are reported applications for skeletal CT.

Developmental elbow disease

Radial carpal bone fracture

Acetabular/pelvic fracture

Digits

Skull

CT eliminates the problem of superimposition of surrounding structures allowing the nasal cavity, mandibles, temporomadibular joints, and middle ear to be assessed in fine detail.

Canine skull

Nasal tumour

Brain and cranial vault

In general, while CT allows evaluation of the brain it is not regarded as the imaging modality of choice in most instances. However, where there are issues with funding or availability of MRI, contrast CT may be a useful alternative.

Brain tumours

Spine

CT of the spine eliminates superimposition of adjacent structures and allows Mulitplanar reconstructions for detailed assessment of fractures, alignment of vertebral bodies, vertebral malformations, discospondylitis and neoplasia. Contrast CT also provides accurate localisation of acutely extruded intervertebral discs, normally
diagnosed by conventional Myelography (time consuming and occasionally non diagnostic) or MRI (expensive and not readily available).

Cervical spine: atlanto-axial subluxation investigation

L1-L2 intervertebral disc extrusion

Thorax

CT is very useful for assessing the lung parenchyma and provides superior information compared with conventional radiography and is not possible with MRI due to movement artefact. Helical CT scanning provides rapid image acquisition of the thorax reducing the effects of respiratory motion. The detection of pulmonary metastasis (tumours) is improved and the mediastinal structures such as lymph nodes, blood vessels and the oesophagus as well as the soft tissue and bony structures of the chest wall can be viewed in detail. Computed tomography is the imaging modality of choice for the thorax in many circumstances.

Lung lobe torsion

Primary lung tumour

Heart

Metastatic lung tumour

Soft tissues

Evaluation of the extent of soft tissue involvement in many inflammatory or neoplastic conditions is improved by the detail provided by CT and this is further enhanced in contrast CT, where radio-opaque contrast is taken up more readily by vascular tissue. Invasion of surrounding structures is highlighted allowing a more informed decision on
case management to be made.

Liver tumour

Tumour of the kidney

Vessels

Increased speed of helical scanning makes CT angiography possible and most systems have programs which evaluate arterial and venous phase of blood supply. This is invaluable for surgical planning as the blood supply to or involvement of vessels within the are of interest can be determined in advance.

Portosystemic shunt (PSS)

Popliteal artery

Occular

Retrobulbar masses/abscesses and foreign bodies.

Urinary

Contrast enhanced CT for congenital urinary conditions such as ectopic ureter, cystic, ureteric and renal calculi.