MRI (Magnetic Resonance Imaging) scans with the use a strong magnetic field to give detailed cross-sectional images of soft tissue, muscle, nerves and blood vessels. MRI is commonly used at NHNN to diagnose many diseases and injuries including stroke and intracranial bleeds, neuro-oncology, dementia, cognitive disorders, epilepsy, movement disorders, multiple sclerosis and demyelinating diseases, CSF circulation impairment and hydrocephalus using CSF flow Phase-contrast MR techniques, neurometabolic disorders, neuromuscular disorders, infections, spinal diseases and injuries and many more.
The MRI department at NHNN also provides a unique intra-operative imaging service for patients undergoing multiple operations including DBS insertion, craniotomy and thalamotomy. The iMRI suite provides an operating theatre and MRI scanning capabilities during surgery.
Advanced neuroimaging techniques used at NHNN include fMRI (to locate specific functions in the brain), tractography (to identify white matter tracts), MR perfusion (to assess brain perfusion alterations in neurological diseases), MR spectroscopy (to assess metabolic changes in the brain) and MR neurography (for the evaluation of peripheral nerve disease), using state-of-the art post-processing tools and reporting techniques.
The Department is currently undertaking some MRI scans at a number of locations other than the National Hospital for Neurology and Neurosurgery in order to keep waiting times as short as possible. You may be contacted by one of our local partner sites about your appointment. Each of the centres is scanning on equivalent scanners and using the National Hospital protocols. Please be assured that there will be no charge to you.
Please read your appointment letter for guidance on arrival time and eating and drinking before your scan.
Before your scan the radiographer may ask you to change into a hospital gown, where necessary. Please feel free to bring your own dressing gown or metal-free clothing with you.
You will be asked to place your belongings in a secure locker, no metallic items such as coins, watches, phones or cards can be taken into the scanner. The radiographer will go through a series of questions about your medical and surgical history and may also review your medical records to ensure you are safe to go in the scanner.
The radiographer will verbally confirm if you are happy to proceed with your scan. If you do not wish to have the scan or are undecided, please inform the radiographer.
Please contact the Neuroradiology department before your appointment if any of the following apply:
- You have any metallic implant, device or pacemaker in your body
- If you have ever had metal fragments in your eyes
- You have a history of renal problems, renal failure or have ever been on dialysis
- You have a known allergy/previous reaction to gadolinium based contrast
- There is any possibility of pregnancy
- You require an interpreter.
The MRI scan is very noisy, the length of the scan will vary depending on the area of the body to be examined; times can range from 20 minutes to two hours. You will be asked to lie on a couch and keep as still as possible; you will be given earplugs and headphones to protect your hearing. Radiographers will communicate with you over a two-way intercom in between scan sequences. An emergency call button will also be provided.
During an MRI scan it is sometimes necessary to give you an injection gadolinium-based contrast (a type of dye that highlights structures in the body) to provide more detail and information for your referring clinician. This contrast injection will be administered by a radiographer through a cannula (small plastic tube), usually placed in a vein in your arm.
You will notice once the scan begins it is very loud; this noise is created due to the magnetic fields. We will provide you with earplugs and ensure these are fitted correctly before starting the scan.
Occasionally some patients may get peripheral nerve/muscle stimulation during the scan, e.g. pins and needles or twitching in your fingertips. This is normal and should subside shortly after your scan. We will provide you with a call button, which you can press at any time if you cannot tolerate the noise or do not wish to continue the scan.
If your scan is particularly lengthy you may start to feel slightly warm. This is due to the radiofrequency energy applied during the scan and how the molecules in your body react to this. You will be monitored throughout your scan by the radiographers and may stop the scan if you do not feel well.
Currently there is no evidence to suggest MRI scans cause any long-term or serious effects.
During your scan you may require a contrast agent. Contrast agents are safe drugs: however, as with all drugs, they have the potential to cause an allergic reaction. The department and staff are fully equipped to deal with reactions in the rare event of this happening.
If think you might be or are currently pregnant, please contact Neuroradiology prior to your scan. To ensure the scan is absolutely necessary, your referring doctor or clinical nurse specialist and a consultant neuroradiologist will need to have a discussion of the risks and benefits. They may decide to postpone the scan. This is due to the acoustic noise from MRI and its potential unknown effects on the hearing of your unborn child. If your scan requires contrast we can provide you with up to date guidance on your breastfeeding.
Following your scan you will be able to go home. You can eat, drink and resume your normal activities straight away. If you have had a contrast injection you may be required to remain in the waiting room for up to 30 minutes, following this your cannula will be removed. You may be advised to gently increase your fluids for the rest of the day.
Your scans will be reported by a neuroradiologist and your results will be sent back to your referring clinician, ahead of your next scheduled consultation.