0562/SAH/1112/SAH

MRI Imaging of GP Medicare Eligible Conditions

By Dr. Andrew Stuart

Radiologist

Sydney Adventist Hospital

Learning Objectives

• Indications for GP referred Medicare eligible MRI scans

• MRI imaging appearances of selected cases

• Benefits to patients in being able to access rebatable MRI

• Precautions and contraindications with MRI referral

Criteria for GP referred for Medicare eligible MRI scans

• MRI Head for unexplained Seizure(s) or Chronic

Headaches

• MRI Cervical Spine for Cervical Radiculopathy or Trauma

• MRI Knee for Acute Knee Trauma with possible Meniscal

Tear or Anterior Cruciate Tear

ABSOLUTE CONTRA-INDICATIONS FOR MRI

• Pacemaker or defribillator wires (now a pacemaker that is MRI safe)

• Metallic FB`s in the eye

• Swan-Ganz catheter

• Deep brain stimulator

• Bullets or gunshots pellets near great vessels or vital organs

• Cerebral aneurysm clips if magnetic (includes unknown)

• Cochlear implant

• Magnetic dental implant

• Drug infusion devices

RELATIVE CONTRAINDICATIONS FOR MRI

• AAA stent

• stapes implant

• implanted drug infusion device

• neuro or bone growth stimulator

• surgical clips, wire sutures, screws or mesh

• ocular prosthesis

• penile prosthesis

• joint replacement or prosthesis

• other implants, in particular mechanical devices

• too large patient

• claustrophic patient

• inability to lie still

• surgery in previous 6 weeks

Nephrogenic systemic fibrosis (NSF)

• Rare and serious condition involving fibrosis of skin, eyes, joints and internal organs.

• Occurs in patients exposed to gadolinium with severe renal disease.

• Please ensure if you are referring a patient for MRI who has suspected renal disease or who is elderly that there is a relatively recent creatinine.

• At the SAN we use Gadovist which has not had a definite case of NSF associated with its use.

28 yr old female

• Suspected cervical trauma playing netball p/w

left sided neck pain

• Probable migraine

• Exclude spinal pathology

Sagittal water sensitive MRI sequences T2 STIR

TOF MRA of neck arteries

Axial T1 fat saturation

Axial diffusion scan (DWI)

Take home points:

• Diagnosis = Lt vertebral artery dissection

with small embolic acute infarct

• Should have started with cervical spine X-

ray

• Need to have a high index of suspicion for

carotid or vertebral dissection

• CT angiogram has better spatial resolution

than MR angiogram but radiation dose

66 yr male p/w focal epilepsy and increasing cognitive

problems

Axial susceptibility weighted imaging

(SWI)

Axial FLAIR Coronal

Take home points:

• Diagnosis = Cerebral amyloid angiopathy

• Any new onset epilepsy needs investigation

• CAA is common in the demented elderly

normotensive pt.

• MRI susceptibilty imaging is needed to detect these

multifocal microhaemorrhages ( CT occult )

• Amyloid angiopathy is a common cause of

spontaneous lobar haemorrhage in elderly

35 yr old female p/w severe headache in upright

position

Coronal Imaging through posterior cranial fossa

FLAIR Susceptibilty weighted image

Sagittal water sensitive sequences

T2 STIR

Take home points:

• Diagnosis = Intracranial hypotension

• MRI (SWI) is good for detecting subtle

haemorrhage- new and old

• CT is good for acute haemorrhage only

• Often need to image brain and spine as

pathology is inter-related

38 yr female p/w common migraine over past

few years better during pregnancy and

lactation. Any vascular or pituitary abnormality?

T1 post gadolinium

Sagittal Coronal

s

Coronal SWI (susceptibility image)

Coronal T2 FLAIR Axial

MRV performed 4/12 later

Take home points:

• Diagnosis = Dural sinus thrombosis

• Venous thrombosis progresses to venous infarction in

50% cases

• Venous infarction is eliptogenic and is associated with

headache, papilloedema and neurological deficits

50 yr female old p/w long standing migraines. Acute

onset drowsiness. Cerebral sinus thrombosis ?

TOF MR Venogram

Take home points:

• Diagnosis = uncertain but probably vasculopathy

associated with migraine

• T2 FLAIR hyperintense foci are a common finding

> 60 yrs

• Felt usually to reflect chronic small vessel

ischaemic change associated with ageing

• Significance controversial and findings non

specific although associated with increased risk

of CVA

• In the younger patient the differential includes

vasculitis, demyelination, vasculopathy, migraine

• ? perivascular demyelination around

arteriosclerotic vessels ? myelin pallor with

dilated perivascular spaces ? small lacunar

infarcts

26 yr old male p/w headache

Sagittal T2(top) and T1 (below)

Take home points:

• Diagnosis = Chiari type 1 malformation

• MRI good for sagittal plane, anatomical detail

at skull base as well as syrinx evaluation

• Fundamental problem is underdevelopment

of posterior cranial fossa

• Numerous symptoms including subocciptal

headache

• Usually present in 2nd and 3rd decade

• Treatment controversial – do not usually

intervene if asymptomatic unless syrinx

16 yr old male p/w locking knee

Sagittal PD fat sat Coronal PD fat sat

Axial PD fat sat Coronal PD

Take home points:

• Diagnosis = bucket handle meniscal tear

• Displaced meniscal fragment resembles

the handle of a bucket

• Pain/locking after single traumatic event

• Requires surgical intervention

• Locking associated with a meniscal tear

indicates a displaced meniscal fragment

17 yr old female p/w acute knee injury with

instability episode. ? ACL.

ACL injury occurs when the femur and tibia rotate in opposite

directions under full body weight

Normal knee Ruptured ACL with anterior tibial translation

Avulsed intercondylar notch Segond fracture

Take home points:

• Injury usually caused by pivot shift mechanism

• Associated meniscal tears common

• Posterolateral corner injury associated with marked

instability

24 yr old female p/w severe neck pain after fall

Axial CT through C1 and C2

Sagittal CT reconstructions though Cervical

spine

Sagittal T2 weighted scan through cervical spine

Coronal Stir and Axial T2

MRA of carotid and vertebral arteries in neck

Take home points:

• Usually perform X-Ray first

• CT performed next if X-ray normal but still

clinical concern or if fracture and need to

define

• MRI normally has role to define soft tissue

injury including vascular injury

• MRI is not a substitute for CT in suspected

cervical spine fracture

43 yr male present with left cervical radiculopathy

Sagittal T2 Sagittal T1

Oblique sagittal T2 Axial T2 at C5/6

level

Take home points:

• MRI best way to asses for cervical foraminal

stenosis (oblique sagittal T2)

• History should if possible give nerve root

level based on clinical examination

• A CT guided perineural steroid injection can

be performed to relieve symptoms

Diagnostics GP Conference

Tuesday 18th March 2014

SYDNEY ADVENTIST HOSPITAL

PRESENTS

SPEAKERS

Dr Ross Bradbury – Antibiotic

Therapy for GPs: An Update

Dr David McHarg – Overview of

PET-CT

Dr Andrew Stuart – MRI Imaging of

Conditions that are Medicare

Eligible for GP Referral

CONVENOR

Dr James Cheatham