MRI and CT have totally revolutionised the practice of medicine over the past 30 years. Conventional MR and CT systems are designed so that the patient is scanned in the horizontal position (typically supine), and in the case of MRI, is either examined in a tunnel, with a high-field magnet, or between two large magnetised plates in a low – field, so called ‘open’ system.
Traditionally, high-field (e.g. 1.5T or 3T) ‘tunnel’ systems are judged to give the best quality images. However, a significant proportion of patients are too claustrophobic to tolerate the confines of the tunnel. Also, very limited access to the patient whilst in the tunnel causes difficulties with scanning children, obese and confused patients, or those unable to lie supine and still for the required time. Traditional ‘open’ scanners are less claustrophobic but are lower in field strength (typically 0.2 – 0.5T, although higher field strength scanners are now becoming available), with some compromise in image quality, although the constant improvement in both coil technology and software over the past few years has significantly narrowed the gap in image quality between low and higher – field systems. Both conventional tunnel and open systems only scan in the supine, non-weight-bearing position.
United Open MRI Ltd have installed three Upright MRI scanners into dedicated centres in Central London, Leeds and Birmingham. The ability to scan patients in the upright, weight-bearing position is unique to these machines. In London the scanner is a FONAR 0.6T machine, and in Leeds and Birmingham a MROpen 0.5T machine manufactured in Italy by Paramed Medical Systems.
The revolutionary design of the scanner enables patients to simply walk in and be scanned. The Upright MRI allows all parts of the body, particularly the spine and joints, to be imaged in the weight-bearing state. The scanner is equipped with a unique patient handling system that moves the patient into the magnet and places the anatomy of interest into the centre of the magnetic field. It also can rotate the vertically-orientated patient into a horizontal position (or anywhere in between) so the patient can be scanned lying down as in conventional MRI scanning. Because the patient is typically upright (either standing or sitting in a special chair) or at say, a 30 degree angle, and has an unrestricted view in front of them, problems with claustrophobia are effectively eliminated. What has also been found is that patients who were not even able to tolerate conventional ‘open’ MR scanners have been scanned successfully and have reported no discomfort in the upright system.
It should come as no surprise that the MR appearances of the spine are not necessarily the same in the upright as in the supine position, because of the weight-bearing state of the former. But of course, the key question is: does this method of scanning influence patient management?
In a paper presented to the European Society of Skeletal Radiology (ESSR) in July 2005, Smith and Siddiqui reported twenty-five patients referred for MRI of the lumbar spine for sciatica following at least one prior, “normal” MRI examination within six months of referral. 14 men and 12 women aged between 38 and 67 years of age were scanned using an upright MRI Scanner. Each patient was scanned supine, standing erect and in the seated position. In the seated position, images were made with the back in neutral, flexed and extended. Sagittal T2 and Axial T2 weighted sections were made through the lower five intervertebral discs in each position.
In twelve cases, no significant abnormality was seen in any of the five postures. In thirteen, abnormalities were demonstrated in one or more of the seated postures that were not evident in the conventional supine examination. In three cases lateral disc herniation was only seen in the seated position. In six cases the presence of a hypermobile disc at one or more levels was demonstrated. In two cases a previously unsuspected grade 1 spondylolisthesis was shown and in two cases significant spinal canal stenosis was seen in the seated extended position.
In 50% (13/25) of these cases that had previously been investigated for sciatica, a surgically remediable lesion was found. Each of the thirteen patients has undergone appropriate surgery and six months post surgery remained symptom free. Our London centre has been open for a number of years now, and our experience is consistent with the Smith and Siddiqui study, we are detecting findings which show the benefits of weight bearing imaging.
1. Patients who are claustrophobic
2. Patients who are obese or exceptionally large (including some endocrine patients)
3. Patients who are unable to lie supine for the duration of their scan
4. Patients who need to be observed during their scan
Cervical and Lumbar Spine:
1. As a problem-solving modality in those who have had a negative, or unhelpful ‘conventional’ MR examination
2. In patients with a ‘failed-back’ following previous surgery
3. In those whose symptoms are posture-specific – the patient is scanned in the position that causes the pain. Flexion, extension and rotation views are all achievable
1. Other joints of the body that are symptomatic in specific weight-bearing positions
Of course, the overall quality of any imaging service can only be as good as the quality of the imaging reports, so all images produced by both Centres are reported by dedicated musculo-skeletal and neuro-radiologists.
Finally, Upright MRI should not be regarded as ‘competitive’ to conventional MRI, but rather as complimentary, potentially answering clinical problems not addressed by the conventional scan, and scanning those patients who are unable, for whatever reason, to benefit from the conventional approach to performing MRI. It is with these objectives in mind, that our Centres have well established links with the NHS and Private Practice, in the hope and expectation that the amazing clinical powers of MRI are further expanded for the benefit of all patients.
- Image quality is exceptionally good, and all studies are reported by specialist radiologists
- Claustrophobia is not a problem with this scanner
- It can be used in a variety of clinical situations where conventional MRI is unsuitable
- It can sometimes reveal pathology not identified with conventional MRI