CT Referral Guidelines

South Tees Hospitals have developed the following referral guidelines to support the delivery of a primary care focused CT service.

Referrers are encouraged to clearly state the clinical condition they wish to confirm or exclude. In effect, referrers should always ask themselves the question: “Have I fully explained the clinical problem”. The layout of the request form should allow for this. This would hopefully reduce the need for requests for additional information from the GP, which may delay the scan.

Advice is easily and quickly available to referrers via the radiology departments on (01642) 282639 for James Cook or (01609) 763060 for the Friarage. Often a short discussion with a radiologist will clarify the appropriate imaging.

It is essential CT reports are accurate, concise, and informative and provide clear advice to the referrer in the form of a “conclusion” Therefore as much relevant clinical history as possible must be provided by the referrer.

Referrers must bear in mind the large radiation doses often incurred with CT. The following principles should be adhered to:

  • Will the result of the test affect clinical management?
  • Is the test being requested too quickly?
  • Is the test the correct one?
  • Has the test already been performed elsewhere or in the recent past? If so the need for repetition should be seriously questioned.

Pregnancy or suspected pregnancy

CT often carries a very large radiation burden. The prime responsibility for identifying patients who are, or might be pregnant lies with the referrer. Where possible women of child bearing age should not be exposed to ionising radiation. If pregnancy is confirmed, the need for investigation should be re-evaluated, and ideally discussed with a Specialist Radiologist.

The following guidance has RCR approval:

  • If a patient is unsure as to whether she is pregnant, she should be asked if her menstrual period is overdue.
  • If there is no possibility of pregnancy, the investigation can go ahead.
  • If pregnancy is confirmed or very likely, the referrer should discuss with a specialist radiologist.
  • If pregnancy cannot be excluded, and menstruation not overdue, it is probably best to wait until the onset of the next menses before imaging is undertaken unless it is deemed unsafe to wait. In this case the referrer should discuss with a specialist radiologist. If not urgent, the examination should be scheduled for the first 10 days of the next menstrual cycle.

Standards and safety issues concerning IV iodinated contrast agents in adults.

IV contrast is commonly administered in the CT suite, fortunately life threatening reactions to injected contrast media are rare, occurring in approximately 0.004% of cases. Patients at risk of contrast induced nephrotoxicity include:

  • Previous contrast reaction
  • Asthmatics
  • Renal impairment
  • Diabetes mellitus

Serum creatinine level is the most readily available indicator of dysfunction, a level of 130 micromoles per litre has been arbitrarily set as the cut off point.

In patients at risk of renal dysfunction, an up to date serum creatinine level should be made available to the Imaging department

Important

It is important that referring clinicians inform Imaging departments of previous reactions to contrast media, renal impairment and diabetes mellitus.

CT is relatively expensive and generally imparts a high radiation dose (especially in oncology). In general CT is widely used and indicated in the following areas.

Intracranial problems. Although MRI gives much better contrast sensitivity and multiplanar capacity, CT is still sufficient to answer the clinical question in most cases.

It is still employed as the first line staging investigation for a large number of cancers. Most follow up is performed with CT.

Trauma (although MRI is invaluable with suspected spinal cord trauma)

Clinical indications:

  • “Standard” brain. Indications for CT include
  • R/O stroke (non-haemorrhagic)
  • R/O haemorrhage
  • R/O tumour or other SOL
  • R/O subdural / Epidural
  • Sudden severe headache
  • MRI scanning is generally considered to be the modality of choice in
  • Multiple sclerosis/white matter disease
  • Pituitary and parasellar problems (skull x-ray NOT indicated)
  • R/O acoustic neuroma
  • Posterior fossa/brainstem disease
  • Temporal lobe epilepsy

For orbital problems, either CT or MRI could be used depending on the question to be answered and local availability.

ENT protocols

Acute sinusitus should be diagnosed and treated clinically, if it persists past 10 days on appropriate treatment, x-ray of the sinuses may be required. However signs on x-ray are often nonspecific. CT of the sinus enables visualization of the presence and distribution of disease and sinonasal anatomy.Indications for CT sinus are as follows:

  • Failure of maximal medical treatment
  • Development of complications
  • Assessment for surgery (FESS)
  • Malignancy is suspected

Refs

RCR guidelines; making the best use of a department of clinical radiology (4th edition,1998).
American College of radiology “appropriateness criteria”
Standards for Iodinated contrast agent administration in adults (RCR 2006)
Diagnostic medical exposures: advice on exposure to ionising radiation in pregnancy (NRPB 1998)