Chiari / Syringomyelia MRI screening

 

Stone Lion Veterinary Centre, Goddard Veterinary Group, 41 High Street, Wimbledon, SW19

 

What is MRI?

Magnetic resonance imaging (MRI) makes a picture of the water molecules in the body. It is excellent way of looking at the central nervous system which does not image well using traditional x-ray technology. The pictures are presented as a series of “slices”; analogous to a sliced loaf of bread. Click here for more information about MRI

What is Chiari/Syringomyelia (CM/SM) screening?

CM/SM MRI screening (sometimes called mini MRI) is limited MRI study of the back of the brain and upper neck provided at low cost by veterinary practices and intended as an economical screening test for dog breeders.

Can CM/SM screening be used as a low cost diagnostic test for SM in a dog with neck pain or other clinical signs?

The study is of the back of the brain and upper neck only and so the true extent of the syringomyelia (i.e. how much of the spinal cord involved) will not be ascertained. More importantly other diseases which could explain the clinical signs may be missed, e.g. a herniated intervertebral disc. In addition there is no consultation with Dr Rusbridge or another veterinary surgeon to discuss the procedure or the results. The breeder/owner is a sent a report that specifically relates to the presence or absence of syringomyelia. For example of report click here

How do I arrange a CM / SM MRI screen at Stone Lion Veterinary Centre.

The scans may be booked by contacting the reception team on 020 8946 4228 (stonelionvets@goddardvetgroup.co.uk) or Neurology Nurse Sandy Griffith RVN on 020 8946 4228 (SGriffith@goddardvetgroup.co.uk)

Any dogs with a pre-existing medical condition making anaesthesia undesirable will not be MRI scanned. To avoid a wasted journey, it is the responsibility of the owner to ensure that the dog has been deemed healthy by their own veterinary surgeon prior to booking the scan. You will be asked to sign a consent form pertaining to this.

What is the cost of a CM / SM MRI screen?

1-2 dogs £250 plus VAT

3 or more dogs £165 plus VAT

There is an additional discount of 10% for 10 or more dogs

To obtain the reduced rate for single dogs is it possible to attend a SM MRI Screening day or to join a group of breeders in a similar situation. For details and/or to add a name to an existing list contact Neurology Nurse Sandy Griffith RVN on 020 8946 4228 or SGriffith@goddardvetgroup.co.uk

For comparison the cost of a diagnostic MRI scan (including interpretation and anaesthesia) is £941.60 plus VAT.

What documentation etc is required

1) admission form 2) registration certificate 3) microchip/tattoo documentation

Please fill in the admission form and email / fax or post to SLVC to confirm the booking.

Please bring 3 copies of the kennel club registration certificate or (preferred) scan and email to SGriffith@goddardvetgroup.co.uk  and/or stonelionvets@goddardvetgroup.co.uk

The dog must have permanent identification i.e. microchip or tattoo. Please bring or email copies of microchip / tattoo documentation or alternatively a microchip can be implanted at the time of the MRI scan (cost £15 plus VAT).

Is an anaesthetic necessary?

The head and neck must be absolutely motionless during the procedure and this can only be achieved with heavy sedation or light anaesthesia. At Stone Lion Veterinary Hospital we prefer a light anaesthesia as we can be more confident that the dog receives enough oxygen.

What anaesthetic do you use?

The typical anaesthetic for MRI at Stone Lion includes a preanaesthetic of Dexdomitor ® and butorphanol followed by intravenous propofol. This allow placement of an endotracheal tube into the dog’s throat and anaesthesia can then be maintained on isoflurane gas and oxygen. The advantage of using Dexdomitor ® is that it markedly reduces the amount other anaesthetics required and can be reversed during or after the procedure (using Antisedan ®) so that the dog wakes up quickly and with a clearer head. Dexdomitor ® also has the advantage that it reduces anxiety and affects memory i.e. reduces the stress to the dog. The choice of anaesthetic may be adjusted if the dog has other medical problems.

How long does the scan take?

The actual MRI scan takes 30 minutes however you should allow at least 2 hours per dog to allow your pet to fully recover from the procedure. Dogs are normally given a small meal and a drink before discharge.

Do you use gadolinium contrast agent for CM/SM MRI screening?

No, gadolinium contrast agent is not used for CM/SM MRI screening at SLVH.

When do I hear the results?

You will be posted and /or emailed a report within 1 week of the procedure. To produce a report, proof of ownership and the dog’s pedigree name with registration must be provided and the dog must have permanent identification. For an example of a report click here

There will be no consultation with Clare Rusbridge or other veterinary surgeon to discuss the procedure or the results. If you desire this contact then you may book a consultation at the usual clinic times and cost.

Why Stone Lion Veterinary Centre - does getting good quality images matter?

Low cost MRI screening for SM is performed in many cases on ESOVATE MRI machines. Images of excellent quality can be obtained but operators should beware of taking short cuts either for time or economic reasons. Subtle SM may be missed. The images above are taken from the same dog with a narrow syringomyelia (arrow). The image on the left is taken with a short acquisition times and the SM is not appreciable. The image on the right is a longer acquisition time. The consequence to the breeder of missing subtle disease may be devastating as his or her whole breeding program may be based on the assumption that the dog in question is unaffected. At Stone Lion we are proud of the service we provide.

 

I have had MRI scans taken elsewhere – can I have them reported by Clare Rusbridge?

For outside reporting the following is required

1) Submission Form

2) Copy of Kennel Club registration documents

3) Verification (i.e. signature by veterinary surgeon) that microchip / tatoo pertains the animal scanned

4) CD of DICOM images (film of limited is images not acceptable)  - for details of which images should be obtained click here

NB CD will not be returned

5) The fee is £35 plus VAT for EU residents or £35 for non-EU residents. Payment is in UK pounds. It is possible to use PAYPAL (for details contact CRusbridge@goodardvetgroup.co.uk ).

Address for submitting images and documents – Clare Rusbridge, Stone Lion Veterinary Centre, 41 High Street, Wimbledon, SW19 5AU

 

I am a veterinary surgeon who is performing CM/SM MRI screening - what are the protocols?

Click here for additional information

Are the MRI results submitted to the Animal Health Trust for the Estimated Breeding Value database?
Yes. For more information about this scheme click here

 

At what age should dogs have CM/SM MRI Screening? 
The minimum screening age is 12 months. It is also recommended that breeders determine the MRI status of their breeding dogs at 2-3 years and again when 6 years of age. This will provide further information about that individual dog’s estimated breeding value (EBV) (and therefore the EBV of that individual dog’s offspring).

 

When is the proposed BVA / KC MRI screening scheme going to start?
Unfortunately the process of conception to an up-and- running scheme can be lengthy. The proposed scheme has been submitted to the BVA/KC Management Committee for their consideration and is currently in progress.

 

Why is severity of Chiari malformation (cerebellar herniation) is no longer assessed?
For 2 reasons 1) studies could not demonstrate a relationship between the degree of cerebellar herniation and presence of syringomyelia 2) Widely differing MRI techniques and machines meant that an accurate comparison between dogs is not possible. In particular poor positioning and low quality images may “improve” a chiari malformation.

How head position affects apparent chiari malformation. The dog on the left, positioned in dorsal recumbency (supine) may have a mild chiari malformation however it is difficult to be sure.

It is also essential that the head and neck are straight and in line with each other

MRI images from a dog positioned with the head slightly rotated with respect to the neck. The images on the left were obtained for assessment of the cervical spinal cord and demonstrate a cervical syrinx (midsagittal cervical spine). However the section though the brain is slightly oblique giving an impression that the dog has only a mild herniation of cerebellum through the foramen magnum. The image on the right indicates the true appearance of the cerebellar herniation (midsagittal brain).

The images above illustrate how difficult it is to make assessments of severity of cerebellar herniation using isolated "snap shots" especially the person interpreting the MRI scan is unaware of how the dog was positioned. It also illustrates how important it is to position the dog accurately. A study into the effect of positioning on apparent severity of chiari malformation was funded by the UK CKCS club.