A
A. Head (including ENT problems)

CLINICAL/DIAGNOSTIC

PROBLEM

INVESTIGATION

RECOMMENDATION

(GRADE) 

COMMENT

DOSE

Congenital disorders

MRI

Indicated (B)

Definitive exam for all malformations. CT may be needed to define bone and skull base anomalies. Sedation of GA may be required for infants and young children

0
 
Acute stroke CT Indicated (Diagnosis B, treatment A) A policy of CT for most strokes as soon as reasonably possible is to be encouraged, but at least within 48 hours, as this will ensure accurate diagnosis of the cause, site and appropriate primary treatment and secondary prevention.

II
MRI Specialised investigation (B) MRI should be considered in young patients with stoke, in patients presenting late where it is essential to know whether they have previously had a haemorrhage and in suspected posterior fossa stroke in patients in whom it is important to demonstrate the site of the stroke lesion.

0
US carotids Indicated only in specific circumstances (B) Should only be performed in:(1) those with full recovery in whom carotid endarterectomy is contemplated for secondary prevention; (2) suspected dissection; or (3) young patients, whether disabling or non-disabling stoke.

0
 
Transient ischaemic attack (TIA) CT Indicated (B) May be normal. Can detect established infarction and haemorrhage and exclude disease processes that can mimic stroke syndromes, such as glioma, extracerebral haemorrhage and cerebritis

II
US carotids Indicated To assess suitability for carotid endarterectomy or angioplasty. Angiography, MRA, and CTA are alternatives to show the vessels. MRI and NM can be used to show function

0
 
Demyelinating and other white matter disease MRI Indicated MRI is viewed as the most sensitive and specific investigation for establishing a diagnosis of multiple sclerosis. The diagnosis is made by demonstrating dissemination of clinical events and lesions in space and time.

0
 
Space occupying lesion (SOL) MRI Indicated (B) MRI is more sensitive for early tumours, in resolving exact position (useful for surgery), and for posterior fossa lesions. MRI may miss calcification.

0
CT Indicated (B) CT is often sufficient in supratentorial lesions.

II
 
Headache: acute, severe; subarachnoid hemorrhage (SAH) CT Indicated (B) The clinical history is critical. A clinician should be able to diagnose patients who have classical migraine or cluster headaches without CT. SAH headache comes on typically in seconds, rarely in minutes and almost never over more than 5 minutes. CT will provide evidence of hemorrhage in up to 98% of patients with SAH if performed on a modern scanner within the first 48 hours of ictus. An LP should still be performed on all patients (delayed 12 hours after ictus for xanthochromia) with suspected SAH but with negative CT. CT is indicated in patients with acute-onset headache with focal neurological signs, nausea or vomiting, or GCS below 14. An LP is the diagnostic test of choice for meningitis unless there are focal signs or a significantly depressed level of consciousness.

II
MRI/NM Specialised investigation (C) MRI is better than CT for inflammatory causes. SPECT may be the most sensitive investigation for encephalitis and can provide evidence of circulatory derangement in migraine.

0/II
 
Headache: chronic CT/MRI Indicated only in specific circumstances (C)

In the absence of focal features imaging is not usually useful. The following features significantly increase the odds of finding a major abnormality on CT or MRI:

  • Recent onset and rapidly increasing frequency and severity of headache

  • Headache causing to wake from sleep

  • Associated dizziness, lack of coordination, tingling or numbness

II/0
SXR, XR sinus, XR cervical spine Indicated only in specific circumstances (B) XR is of little use in the absence of focal signs/symptoms

I/I/I
 
Pituitary and juxtasellar problems MRI Specialised investigation (B) Urgent referral when vision is deteriorating

0
SXR Not indicated Patients who require investigation need MRI or CT

I

Posterior fossa signs MRI Specialised investigation (B) MRI is the investigation of choice. CT is often degraded by beam hardening artefacts.

0
 
Hydrocephalus, shunt function CT Indicated (B) CT is adequate for most cases; MRI is sometimes necessary and may be more appropriate in children. US is the first choice for infants.

II
XR Indicated (C) If there is evidence of hydrocephalus on CT, XR can demonstrate the whole valve system

I
 
Middle or inner ear symptoms (including vertigo) CT Specialised investigation (B) Evaluation of these symptoms requires ENT, neurological or neurosurgical expertise

II
 
Sensorineural hearing loss MRI Specialised investigation (B) MRI is much better than CT, especially for acoustic neuromas

0
 
Sinus disease XR sinus Indicated only in specific circumstances (B) Acute sinusitis can be diagnosed and treated clinically. If it persists past 10 days on appropriate treatment, XR sinus may be required. Signs on XR sinus are often non-specific and encountered in asymptomatic individuals

I
CT sinus Specialised investigation (B) CT is useful to demonstrate the presence and distribution of disease and sino-nasal anatomy. Low-dose technique is desirable. CT is indicated for failure of maximal medical treatment, development of complications (such as orbital cellulitis), or if malignancy is suspected.

II
 
Dementia and memory disorders, first-onset psychosis CT Indicated only in specific circumstances (A) Yield is low, even in younger patients; neurological signs and rapid progression increase it. Over the age of 65, CT can be reserved for patients with an onset within the last year or an atypical presentation, rapid unexplained deterioration, unexplained focal neurological signs or symptoms, a recent head injury (preceding the onset of dementia), or urinary incontinence and/or gait ataxia early in illness

II
MRI

NM

 Not indicated (B) More sophisticated examinations (MRI, SPECT) have no proven clinical value, although they may be used in research

0

II
SXR Not indicated (A) SXR should only ever be used to show clinically relevant abnormalities of the skull bones.

I
 
Orbital lesions CT Specialised investigation (A) CT remains the investigation of choice. MRI may be of value if CT is unhelpful or gives insufficient detail. Consider US for intraocular lesions

II
XR Not indicated (A) Suspected orbital lesions require specialist referral.

I
 
Orbital lesions: Trauma CT Specialised investigation (A) CT is indicated when orbital trauma may be combined with major facial fracture. If a less severe blowout fracture is suspected, CT is carried out only if the patient is a candidate for surgery

II
 
Orbital lesions: suspected foreign body CT Specialised investigation (A) Indicated when XR fails to show a strongly suspected foreign body which may not be metallic, when multiple foreign bodies are present, or when it is not certain whether a foreign body already demonstrated is intraocular

II
XR orbits Indicated (A) A single 'soft' lateral XR is the only projection required to exclude a metallic foreign body; eye-moving images are only for confirmation of the intraocular position of a foreign body once demonstrated. Prior to an MRI study a posterioanterior XR is adequate to exclude a significant metallic foreign body. If a foreign body is confirmed CT may be required by some specialists.

I
US Indicated (B) US may be indicated for radiolucent foreign bodies or where XR is difficult

0
 
Acute visual loss: visual disturbance SXR Not indicated (A) Specialists can diagnose many cases without resorting to imaging

I
MRI/CT Specialised investigation (A) MRI is preferable for suspected lesions of the optic chiasm. CT is preferable for orbital lesions.

0/II
Cerebral angiography Specialised investigation (A) Specialist referral is indicated.

III
 
Epilepsy (adult) MRI Specialised investigation (B) Structural imaging is the technique of choice. Higher soft-tissue resolution and multiplanar capability give greater sensitivity and specificity for the identification of small cortical lesions. Particularly valuable in the evaluation of partial epilepsy, e.g. temporal lobe epilepsy

0
CT Specialised investigation (B) Following trauma. CT may complement MRI in the characterisation of lesions, e.g. calcification. II
NM Specialised investigation (B) Ictal SPECT or interictal PET is useful in planning of epilepsy surgery when MRI is negative or its results conflict with EEG or neurophysiological evidence. Regional cerebral blood flow (rCBF) agents are also of value II
Back to contents

Next

 
 
See ad