ROSSDALES EQUINE HOSPITAL & DIAGNOSTIC CENTRE Cotton End Road, Exning, Newmarket, Suffolk CB8 7NN Vet Vetwatch www.rossdales.com Profile MAGNETIC RESONANCE IMAGING the more motion artefact is agnetic resonance How MRI works By Sarah E Powell When is an MRI scan Name: Sarah E. Powell imaging (MRI) When the area (i.e. tissue) we are appropriate? present on the images, preventing Qualifications: MA VetMB describes the interested in is placed into a strong MRI scans are reserved for cases detection of certain injuries. MRCVS M Not all horses make suitable Year of Qualification: 2002 method of imaging the horse magnetic field and a short pulse of where lameness has been localised of the foot in detail, both of which Main interests: My main area is by stimulating the molecules in radio waves is applied, the tissues to a specific region by nerve and patients for standing MRI equine orthopaedic disease with are frequently implicated in foot the tissue to ‘resonate’ when a ‘resonate’ and a weak ‘signal’ joint blocks and a definitive procedures. Some horses will not an emphasis on diagnostic lameness. This is particularly true imaging. I have a special interest magnetic field is applied to echoes back from the tissue. The diagnosis has not been possible tolerate the procedure well, or are of what is commonly called too small to be comfortably in computed tomographic and them. echo varies depending on the type using other imaging techniques. magnetic resonance imaging and ‘Navicular Syndrome’ (NS). A The most common application is of tissue present in the anatomic In almost all cases an X-ray and/or positioned within the magnet. the early detection of stress number of different structures can to investigate causes of foot pain site being imaged. This depends on ultrasound examination will still be Your veterinary surgeon will best injuries in racehorses. be implicated in NS, including the I graduated from the University in horses when a specific diagnosis the amount of hydrogen ions necessary. In some instances, advise you as to when it is MRI is particularly useful for imaging the foot deep digital flexor tendon, the of Cambridge Veterinary School is required to aid prognosis and (water molecules) present in the disease may be suspected but not appropriate to use MRI in lameness in 2002. I completed an equine impar ligament and the suspensory enable more appropriate tissue. Ligament, bone and tendon confirmed on X-rays and MRI may diagnosis. Factors such as cost, internship in Canada and spent (‘T’) ligament of the navicular time in first opinion equine treatment/management. MRI first have a characteristic signal on MR be indicated to fully evaluate the insurance status of the animal, the bone, which carry different length of time the horse has been practice before joining Rossdales became available to equine images. The images appear as injury. A good example of this is in gather all the information needed, the radiologist and lameness in 2005. I am one of four senior prognoses and may require patients in the mid 1990s, but, black and white ‘slices’ through the the detection of stress fractures in lame, whether the lameness is complete any necessary nerve clinician to discuss the case in light orthopaedic clinicians at individual therapies. However, until 2004, a general anaesthetic tissues. Abnormal signal can be the racehorses (e.g. those in the fetlock improving satisfactorily over time blocks and to acquire a of the information the MRI has Rossdales Equine Diagnostic horses often present to the Centre, where we are proud to be was required to carry out the scan. result of a number of disease joint and upper cannon region). and whether or not any comprehensive set of MR images. provided. The horse then relaxes in lameness clinician in a similar way, recognised as world leaders in More recently, an MRI scanner has processes within the tissue, such as MRI is not a screening technique. medications have been carried out The scan takes about one hour per his stable whilst decisions are made equine diagnostic imaging irrespective of the specific may influence the decision. site scanned depending on the regarding his management. The techniques. I currently head the been developed that enables us to inflammation or degeneration. A horse, under mild sedation, positioned in the MRI scanner for imaging of its lower It is imperative that everything has imaging facility at the Diagnostic scan horses standing, under mild forelimb structures involved. complexity of the case and the following day any other procedures been done to specifically localise Centre and I am particularly sedation – removing the risk of An added benefit is that unlike the site of pain, otherwise the What can I expect on the temperament of the horse. The or necessary treatments can be Advantages of MRI over MRI can tell us about the difficult to assess fully until the interested in further developing general anaesthesia. Every year, radiography and scintigraphy (bone wrong area may be imaged day of the scan? scan generates between 300-500 carried out. This may seem a little our advanced imaging techniques other imaging techniques BIOCHEMICAL CHANGES long introduction of MRI. X-rays give us around 300 horses undergo an scanning’), MRI does not involve wasting time, money and possibly MRI scanning is a complex and images per foot and the radiologist inconvenient to some owners, (MRI and CT), a subject on which MRI allows us to see what’s going before there is structural damage. information about the bones I publish regularly. MRI scan at Rossdales. The foot, the use of ionising radiation, so leading to an incorrect diagnosis. advanced imaging technique and will need time to read the images however, it maximises the chance on in the tissue right now! This allows us to detect injuries within the foot and the hoof there are no hazardous biological I have lectured extensively at fetlock, upper cannon and knee are Only the lower limbs (up to and takes much longer than X-rays or and reach a diagnosis. At Rossdales of us getting to the bottom of the international and national Radiography and ultrasonography earlier than with other imaging capsule impedes the use of commonly investigated using this effects to either the horse, or the including the knee and hock) can ultrasound. Most cases have been Diagnostic Centre, we admit the problem, formulating necessary scientific meetings and rely on damage to tissues causing a techniques. The foot is a complex ultrasound. Using MRI we can now conferences. Additionally, I act as method. vets and technicians carrying out be imaged. However, the higher up lame for significant periods of time horse on the day of the scan and treatments and therefore STRUCTURAL change, whereas anatomic area that had been image the bone AND soft tissues the scan. a consultant and provide image the limb the scanner is positioned and it is essential to allow time to keep the horse overnight to allow optimising his chance of recovery. reading services to a number of other veterinary practices wishing to improve their own imaging A week in brief... skills and facilities. I have a number of collaborative equine clinical research projects in Monday: A National Hunt inconclusive about the degree of region. The colt galloped on be some way from propagating this apparently straightforward Sarah Powell progress and hope to achieve my horse has injured his knee fragmentation of the radial with fellow Saturday and Mike noticed the to a complete fracture; however case had not been going Fellowship of the Royal College during a crashing fall over carpal bone (bone within the speakers (left) lameness during a routine pre- the decision is made to err on according to plan! of Veterinary Surgeons in due fences. He has been referred to knee), which is commonly Dr Tracy Turner race trot up on Monday evening. the side of caution and not to course. Rossdales’ orthopaedic surgeon injured in this type of fall. It is (Minnesota X-rays were taken but did not race the colt the following week. Friday: A 3-year-old Richard Payne to repair the decided that a computer USA) and Dr reveal any reason for the Instead he will be rested for Thoroughbred racehorse has fracture under general tomographic (CT or CAT) scan is Renate Weller lameness. The MRI examination several weeks prior to gradually been reported by the rider to anaesthesia. Radiographs are the best way of assessing the (Royal revealed the presence of a small returning to training. Without show signs of back pain. I visit Veterinary fracture and planning the College) at the fracture line in the condyle the benefit of the MRI the colt the yard on Friday evening to surgical repair. British Racing (lower cannon bone) within the may have suffered a more severe clinically examine the horse and School right fore fetlock. The fracture is injury. MRI image of the coffin joint with a assess for signs of hind limb Rossdales Equine Hospital & Diagnostic Centre Tuesday: Today I’m giving two in the very early stages and may central cyst-like lesion (centre arrow) and lameness, which may mimic (All horse admissions) Thursday: A 5-year-old riding a fracture of the lateral wing of the pedal back pain. I ultrasound some of Cotton End Road, Exning, Newmarket, Suffolk CB8 7NN. It’s also a great chance to catch horse has been referred for bone (right arrowed) the joints in the back and our lectures at a course entitled ‘No Tel: 01638 577754 (Office hours) 01638 663150 (24 hours) Foot No Horse’ at the British up with our referring vets and further evaluation of foot pain. mobile radiography team meet injury. An MRI scan of the foot Email: [email protected] Racing School, Newmarket. find out how some of the cases This gelding had fractured his me at the yard. X-rays reveal revealed the fracture still to be Speakers from the UK and referred to us have been getting pedal bone several months ago, impinging (‘kissing’) dorsal ‘actively’ healing as we would Rossdales Practice abroad are lecturing on a range on! and initially responded well to spines in the back, which may expect at this time. However, it (Ambulatory Practice, Pharmacy and Accounts) of topics including hoof rest and the placement of a explain the signs the rider also revealed a large High Street, Newmarket, Suffolk CB8 8JS. biomechanics, farriery and Wednesday: A 3-year-old special shoe. Recently, an reports. Although this is a subchondral ‘cyst-like’ lesion Tel: 01638 663150 (24 hours) treatment of horses with foot Thoroughbred colt is referred to intermittent left fore lameness complex diagnosis to make, I within the pedal bone, which Email: [email protected] pain. My lectures are about how the MRI facility for further was reported. Radiographs medicate the spaces between was not shown on the earlier X- MRI is incorporated into the evaluation of right fore revealed the fracture was the dorsal spines. If any CT 'slice' through the fractured bone in Beaufort Cottage Laboratories lameness which has been healing as expected and the rays. These ‘cysts’ are often improvement is seen, this helps the knee. These type of images help the lameness investigation and how Fissure fracture (arrowed) in the (Laboratory samples and aborted foeti for postmortem examinations) degree of lameness did not fit associated with intermittent us to assess the significance of The horse’s knee is positioned in the surgeons to plan how best to repair such different forms of navicular localised by my colleague Mike condyle within the right fore High Street, Newmarket, Suffolk CB8 8JS. the usual pattern for such an lameness and could explain why the imaging findings. gantry of the CT scanner injuries. syndrome appear on MR images. Shepherd MRCVS to the fetlock fetlock. Tel: 01638 663017 (Office hours) 01638 663150 (24 hours) Email: [email protected]

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