CT Scanning
CT scanning is a technique whereby X-rays are used to produce a cross-sectional image of various organs in the body, rather like looking at a slice of bread. CT technology has improved hugely so that now the slices have become very thin, and the Kent & Sussex Radiologists have wide experience of using state of the art CT imaging at the BUPA Hospital Fordcombe and, more recently, at the Kent & Sussex Hospital.
CT is the main imaging modality for many abdominal conditions, for the staging and follow-up of many tumours, for many problems within the pelvis, some joints, and the brain.
More recently, CT can be used to look at details of the blood vessels (CT Angiography), used to look both for narrowings (stenoses) in the arteries and also abnormal widenings (aneurysms). CT scanning is also used to look at the detail of the lungs to diagnose many lung conditions such as fibrosis (scarring) and bronchiectasis.
All modern CT scanners have a large role in imaging of trauma, as very detailed 3-dimensional reconstructions of joints and bones can be performed (e.g., the spine and small bones in the hand and foot as well as the pelvis).
CT can also be used to guide invasive procedures such as injecting drugs into specific locations or targeting a biopsy (a procedure where a tissue is sampled) so that diagnosis of a mass or other condition can be made.
Recent advances in CT technology have allowed detailed imaging of the heart. This has arisen because scanners have now become so fast and the slices they produce can be so thin (0.5mm) that it allows very finely detailed images to be acquired, even of an organ which is moving. There are two principle roles of cardiac CT. The first is to look for calcium in the arteries of the heart. This correlates closely with the patient’s risk of having narrowing in the coronary arteries and the associated risk of a heart attack. Patients can be referred for this study at both the Kent & Sussex Hospital and at the Bupa Hospital Fordcombe, either by a specialist or by a general practitioner.
A state of the art application which will be available within the next three months is CT coronary angiography (CTCA). In this investigation contrast (“dye”) is injected into a vein in the arm and a detailed picture of the inside of the arteries is produced. In some situations this will be able to replace conventional catheter angiography of the heart. This has the advantage of being much more convenient since it is an out patient procedure, no hospital inpatient stay is required as it is completely non-invasive and no groin puncture is needed.
CT Preparation
Many CT scans (e.g., orthopaedic scans and brain scans) need no preparation. Sometimes an injection of a dye will be given which allows the blood vessels to be clearly seen.
Many examinations of the body (chest, abdomen and pelvis) will require the patient to drink some oral contrast which allows the bowel lumen (cavity in the centre of the bowel) to be clearly seen and separated from the wall of the bowel or other collections of fluid. Women will often be asked to insert a tampon, which is used as a marker for the vagina.
Risks
CT scans do involve exposure to a small dose of x-ray radiation. However, this dose is small and the risk is therefore very small. Nevertheless, this examination is not undertaken lightly, and the Radiologists (and the referring clinician) would only perform this examination if it is felt that the benefit of an accurate diagnosis far outweighs any possible risk to the patient. This is something that is considered by the Radiologists in all cases before a scan is undertaken.
