Page 146 - Registrar Orientation Manual 2016

Reference:
1257
Effective date:
7 July 2015
Expiry date:
6 July 2018
Page:
29 of 35
Title:
Imaging Guidelines
Type:
Clinical Guideline
Version:
02
Authorising initials:
Multiple Sclerosis (Suspected) and Unexplained Neurological Symptoms MRI requests will not be accepted for patients with neurological symptoms but no signs unless the
patient has been reviewed by a SMO.
Clinical Urgency: Unless there are progressive signs imaging will be deferred until office hours.
Opthalmology
CT or CTA is indicated for the following ophthalmic conditions or patients:
• suspicion of orbital fractures or traumatic optic neuropathy (CT scan brain and orbits with thin cuts: axial, sagital and coronal sections of I .5 mm),
• suspected orbital tumour especially if better delineation of bony anatomy is required (CT),
• to exclude a carotid-cavernous fistula (CTA),
• assessing a patient with a pupil involving third nerve palsy (urgent CTA),
• patients with 4th or sixth cranial nerve palsy, who have vasculopathic risk factors, if there is a
lack of improvement or recovery of the condition (CTA), and
• acute painful anisocoria (Horner’s syndrome) (urgent CTA brain/neck to exclude dissection).
Clinical Urgency: As shown. Urgent CTA is indicated for third nerve palsy and suspected dissection.
Psychosis (First Episode)
The Psychosis Imaging Pathway in the Australian Imaging guidelines supports either CT or MRI as
the imaging modalities in a first episode of psychosis. We recommend CT first.
In Waikato MRI is normally restricted to those patients who have had a CT that has raised uncertainties and where further imaging is required to clarify the diagnosis.
Clinical Urgency: Unless a reduced level of consciousness imaging will not be done after 2200 hours.
Pulmonary Embolism and Deep Vein Thrombosis
Respiratory, with Radiology, have developed PE Guidelines to guide investigation. General Medicine and the Emergency Department have DVT Guidelines
The ‘Choosing Wisely’ recommendations include:
Don’t request any diagnostic testing for suspected PE unless indicated by Wells Score followed by PE Rule-out Criteria (in patients not pregnant). Low risk patients in whom diagnostic testing is indicated should have PE excluded by a negative D dimer, not imaging.
Don’t request duplex compression US for suspected lower limb DVT in ambulatory outpatients unless the Wells Score > 2, OR if less than 2, D dimer assay is positive.
Don’t reimage DVT in the absence of a clinical change.
Clinical Urgency: After hours, the respiratory physician on-call should be consulted before requesting a CTPA. In most patients with suspected PE treatment with LMWH can be started on the basis of the clinical suspicion and imaging deferred until the following day. Ultrasound can usually be deferred to the next working day. If a high clinical suspicion start treatment while awaiting the scan.