As part of your MRI scan it may be necessary to be given an injection, most commonly into a vein in your arm, for administering a special ‘dye’ or contrast media, called gadolinium, or a drug called Buscopan. You can find out more information on this page.
What is Gadolinium Contrast?
Gadolinium is a mineral-based substance used in MRI to improve the quality and visualisation of structures on images. It helps in the assessment of whether there is any disease or abnormality present.
Gadolinium contrast media is specially formulated to ensure its safety for injection into the body, and once injected through a vein, gets eliminated via the kidneys.
How are injections given?
Injections are given via something called a cannula, which is a small plastic tube that sits in the vein. Insertion of a cannula shouldn’t be painful, and some patients may feel a sting or some slight discomfort around the injection site. It will remain in position for the duration of your scan and a little time afterwards. During the injection it may feel cold or uncomfortable but should not be painful. The injection will be given by trained MRI staff and normally takes about 15-20secs. This may be given by hand injection or with the use of a remote automated injector, depending on the area being scanned. You will be given information regarding what injections you have been given during your scan and may be asked to remain in the department for 15-30mins after the injection to make sure you are feeling well before heading home.
Are the injections safe?
Gadolinium contrast is generally an extremely safe drug, although as with any drug side effects or reactions can occur, these are uncommon. In patients with normal kidney function, most of the gadolinium contrast injected will be eliminated in the urine within 24 hours. You should drink plenty of water to stay hydrated and help this process following a scan. In addition to the standard safety questions prior to having an MRI scan, you will also be asked specific questions relating to receiving an injection. These questions help staff assess your suitability for injection and highlight any particular areas of consideration or concern. These will be discussed with you as part of the consenting process, and if there is any concern over you being able to safely have the injection it will not be given.
If you are pregnant or breastfeeding please inform a member of staff before receiving any injection
Can I refuse an injection?
If you are not happy to have the contrast media then you can refuse. This may affect the accuracy of your scan results and require additional imaging to compensate. In most cases, knowledge of needing an injection is known in advance, but on some occasions this does not become apparent until the scan has started. This does not mean something is wrong but will help improve scan quality.
Are there any short-term side effects?
Immediate reactions have been reported at a rate of 0.06%-0.09% (1 in 60-90 thousand) and more severe reactions have an estimated incidence of 0.0025%-0.05% (1 in 25-50 million) – RCR, 2019.
• A small number of patients may notice mild nausea or a headache (about 1-4 in 100)
• Vomiting can occur but is rare (less than 1 in 100 injections)
• Mild reactions can result in approximately 1 in 1000 patients with symptoms such as an itchy rash
• More severe reactions can occur in approximately 1 in every 10,000 patients with symptoms such as difficulty breathing and mouth swelling.
Part of the checking process allows some assessment of the potential for reaction. If there is going to be a reaction, these are normally experienced early on before completion of the scan, and clinical staff are on hand to support and respond as required.
Are there any long-term side effects?
Other conditions relating to the use of Gadolinium are Nephrogenic Systemic Fibrosis (NSF) and retention. Both conditions are potential longer-term side effects resulting from gadolinium breakdown and interactions within the body. NSF is a rare condition associated with the use of gadolinium is a small proportion of patients with severely reduced kidney function. As part of the checks prior to injection, an assessment of your kidney function is made and where there is a need to formally check function beforehand this will be arranged. Considerations that may require formal testing of renal function include:
• Age – patients aged 75yrs or older
• History of kidney disease
• Taking medication for high blood pressure
• History of diabetes mellitus
• Having had, or planning to have, a liver transplant
Retention has more recently been recognised as a result of repeated exposure to gadolinium where small quantities have been found in tissues (mainly bones and the brain) but with no known adverse effects. In both cases, the need for contrast is assessed to ensure that is it essential to support diagnosis of your clinical symptoms and that any benefit outweighs any potential risk of harm. The contrast media used within InHealth are considered low risk, even to those with severe kidney problems, and so further reduces any concerns for harm.
What is Buscopan?
Buscopan is an anti-spasmodic medication commonly used to treat abdominal pain, such as cramps and inflammatory bowel disease. It is given in MRI to reduce the involuntary movement of bowel tissue which can blur images, and therefore helps improve the quality of scans. It is usually given into a vein in your arm but can be given through a muscle in your upper arm or thigh which is slower release and allows the effects to last longer if needed. Either way, you will be asked some questions in advance to ensure your suitability to having Buscopan as some conditions can be exacerbated by the medicine. The main conditions of note are:
• Pre-existing heart conditions such as a fast heart rate, angina and heart failure
• History of glaucoma in your eyes
• Being in urinary retention – having the inability to pass urine combined with the urge to do so and significant lower abdominal pain
Effects of Buscopan usually last for between 30-60minutes and should generally go unnoticed. In some occasion’s patients may notice blurred vision or a dried mouth which will wear off as the drug loses effect. Where any patients experience blurred vision, it is advised that you don’t drive until vision has returned to normal, and so you may want to arrange for someone to collect you to take you home.
Where can I get more information?
Further information is available from the following websites.
www.mhra.gov.uk/spc-pil
www.medicines.org.uk/emc
