COW MRA MRI scan | Medserena Open MRI

Medserena COW MRA scan

MRA scan of the Circle of Willis; non-invasive procedure to help diagnose medical conditions relating to certain arteries of the brain, price includes:

  • Open and Upright MRI scan
  • 20 minutes appointment
  • Radiologist findings report
  • Images on USB at the end of the scan
    and available to NHS trusts via IEP on request
  • Complimentary refreshments

Please wear metal free clothing and if possible, avoid wearing any jewellery. Alternatively, Medserena can provide you with a gown to change into for your scan. Scroll down for more Circle of Willis Magnetic Resonance Angiography scan information.

Many Scans Available within 48 hours

Superior healthcare service with every Private MRI scan

Calm, dignified

Little or no
waiting time

Largest MRI scan centres


Watch TV while

Medical report included

About COW MRA scans

A Circle of Willis (COW) MRA scan is a specialist magnetic resonance angiography scan which examines specific blood vessels at the base of the brain, a connection of several main arteries which supply the brain with blood containing nutrients and oxygen.

This type of scan looks for stenosis (narrowing) or aneurysms, abnormal bulging or ballooning of an artery caused by weakness. If aneurysms grow bigger there is a risk of rupture and bleeding on the brain causing a stroke, which can prove fatal.

This short 15-minute scan focuses on inspecting the Circle of Willis arteries in detail and does not examine any other part of the anatomy. The imaging will examine the Circle of Willis, from all different angles and rotate to assess the patency (whether the blood vessel is open as it should be.) There is no need to have a contrast dye injected, which makes it non-invasive and superior to CT and other types of angiography. A COW MRA is also suitable for patients with allergies to dye and for those with poor kidney function.

The scan is done in the sitting position with equipment over the head, but the front of the machine is open. Having an open scan may be particularly reassuring for you if you suffer from fear or anxiety associated with confined spaces (claustrophobia), particularly tunnel MRI scans.

What conditions can a COW MRA scan detect?

There are two main types of medical problems a COW MRA scan can reveal including:

  • Aneurysms: The Circle of Willis is a very common place for aneurysms to form, especially at arterial branching points. The most common type of brain aneurysm, accounting for eight out of 10 cases, is a saccular aneurysm (also known as a berry aneurysm because of their round shape). In some cases, berry aneurysms can be associated with inherited conditions such as Ehlers-Danlos Syndrome or Marfan Syndrome, both connective tissue disorders that can affect blood vessels, or Autosomal Dominant Polycystic Kidney Disease. Berry aneurysms are estimated to be present in around 2 per cent of the population (although some studies put the figure at 6 per cent). Most don’t rupture, but if they do, they can be life threatening as they can cause a bleed into the cerebrospinal fluid (called a subarachnoid haemorrhage), unless treated with a surgical clip or an endovascular procedure.

Symptoms of a ruptured aneurysm include a sudden excruciating headache, as well as visual disturbance, sensitivity to light, nausea, vomiting, a stiff neck, paralysis, and loss of consciousness. It is a medical emergency that requires immediate treatment.

  • Stenosis (narrowing) of blood vessels: A COW MRA scan can also show up the narrowing of arteries in the Circle of Willis area. This happens due to the build-up of fatty deposits causing plaques to form. Risk factors for developing artery disease include older age, high blood pressure, diabetes, raised cholesterol, smoking and heart disease. These plaques can narrow the arteries and if they break away, they can cause a clot to block the artery. If the clot then breaks away from the plaque it becomes a pulmonary embolism. These clots (thrombus) can potentially travel to the brain causing a stroke.

Around 100,000 people a year in the UK suffer a stroke where the blood supply to the brain is blocked or reduced. If the narrowing is discovered in time, surgery can be performed to correct the problem and prevent strokes and TIAs or mini-strokes.

Other benefits of a Medserena COW MRA scan

Open MRI scanners are a stress-free alternative to using a conventional enclosed tunnel MRI scanner, providing comfort and reassurance for people who suffer from anxiety or claustrophobia. Sitting upright is more comfortable for patients and the open front means patients can speak to a friend or relative or watch television throughout as distraction.

Open MRI scans can also accommodate larger/ heavier patients who might have difficulty fitting comfortably into a conventional tunnel scanner, as they can take weights of up to 35 stone (226kg). However, suitability will depend on the patient’s build and the area of anatomy that needs to be scanned.


The Upright MRI is truly open. There are no tunnels, no narrow tubes. The system is particularly quiet, the examination is comfortable and does not trigger feelings of being in a confined space. This means that the Upright MRI is particularly tolerated by patients who suffer from “claustrophobia”.

Because the system offers you an unrestricted view, you can watch TV or see DVD movies on a large screen during the scan. Wearing headphones – as with other MRI systems – is usually not necessary.

According to the current state of knowledge, there is no danger to the patient’s health as magnetic resonance imaging only uses magnetic fields and radio waves.

Metallic foreign bodies within the patient, such as fixed dental prosthesis, artificial joints or metal plates after treatment for a fracture do not usually pose any danger. However, it is important to clarify that the implants you use are MRI-compatible before the examination.

MRI (Magnetic Resonance Imaging) utilises a large magnet, radio waves and a computer to form images of your body. It is non-invasive, painless and does not use any ionising radiation.

Our truly open MRI can scan you in different positions. Through the utilisation of a specially designed MRI system we can offer weight-bearing scans – sitting or standing. The design of the system allows the patient to be positioned in different postures (e.g. flexion or extension) so that the patient may be examined in the position where they experience pain. The reason to do this is that some pathologies are underestimated or even not seen in a conventional supine MRI scan. The technique has value in many applications: e.g. spine, knees, hips, ankles. This has been proven in scientific studies and documented in peer reviewed publications.

In addition, it offers the possibility of performing an MRI scan on patients who could not otherwise tolerate the examination. This may include the claustrophobic patient, who benefits from the truly open nature of the equipment, and the severely kyphotic patient or emphysema sufferer who simply cannot lie down. It can also facilitate scanning of large patients who struggle to fit conventional ‘bore’ MRI scanners.

Of course, we have a comfortable waiting area but if you want them to stay in the scan room with you, they will also need to fill out a safety questionnaire. There is enough space for a companion. The person can even hold your hand and communicate with you during the examination. This is particularly beneficial when examining teenager.

This depends above all on which part of the body needs to be examined. In the Upright MRI, special examinations can be carried out in various body positions. The entire scan generally takes between 30 and 45 minutes. However, since you have the opportunity to watch TV or DVD, this time will go by much quicker.

Eat and drink normally and, unless your doctor tells you otherwise, please continue taking medications as normal. If you have any special needs (e.g. wheelchair access) please inform us when making the appointment.

Your appointment confirmation; referral letter/form; Medical Insurance details if applicable. We accept all major debit/credit cards.

We will provide a gown/clothing for you to wear when you are scanned. If you prefer to wear your own, please ensure that you wear or bring clothing without any metal fasteners, zips or under-wiring as these cannot be worn in the scan room. The changing room can be locked for safe storage of your possessions.

You will be able to walk into the scanner. It has no tunnel or bore. You will be able to hear us and talk with us during your scan if necessary-and we will be able to see you at all times. Due to its open nature, you will even be able to watch TV or a DVD whilst having the scan. Depending on which part of you is being scanned, you may be asked to sit or stand, and assume different postures (for example bending forward.) The radiographer may place a receiver “coil” around the relevant area of your body. You will need to remain very still while the acquisition is done in order to prevent blurring of the images. You will hear some tapping from the scanner but in general it is much quieter than many other MRI scanners.

You will not feel anything while having the scan. There is no pain or unusual feeling of any type and you will experience no after effects.

YES. There are some things that can prevent you from having an MRI scan. You will be asked to complete a safety questionnaire on arrival at the Centre which will cover the contra-indications-but if you are making an appointment and any of the factors below affect you, please discuss this with us in advance as it may save you a wasted trip.

Contra-indications can include:

  • Pacemaker
  • IUDs
  • Surgical clips
  • Pregnancy
  • Metal fragments in the body
  • Metal pins/plates/screws
  • Joint replacements
  • Metal objects in eyes
  • Cochlear implants
  • IVC filters
  • Metal heart valves
  • Penile implants

It is also important to tell us if you have any tattoos or piercings.

Watches, jewellery, coins, keys, cigarette lighters, penknives, credit cards. piercings, hairgrips, wigs, nicotine patches, and hearing aids must be removed.

Your scan will be reported by a Consultant Radiologist. It will normally be available in a couple of days unless needed urgently. The images and report will be sent to your referring practitioner. If you have a follow up appointment, please make us aware of the details so we can ensure the report and images are available in time.