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 For a far more in depth undertanding than the summary I have posted below:

How Does an MRI Scan Work:

What is an MRI?

A CT scan is most beneficial for observing bone structure, and is less useful for scanning soft tissues in the body. To scan these tissues more effectively, a doctor will usually suggest an MRI scan. MRI stands for Magnetic Resonance Imagery. Rather than using radiation, this procedure exposes the body to a strong magnetic field, which affects the molecules in the body in such a way that a detailed picture can then be produced.

An MRI is performed in a similar way to a CT scan – the patient usually enters a cylindrical machine. However, an MRI scan tends to last longer, and can last up to 45 minutes. An MRI machine also makes a rather loud noise. In some cases, the patient will be injected with a dye, helping the technician to make the image even clearer.

Differences between a CT scan & an MRI scan

One of the major reasons for the increase in use of MRI scans is that they are far superior for collecting images for areas of the body apart from bone. They are also more versatile, and are used for help in diagnosing a wide variety of conditions.

Another benefit to an MRI scan is that it does not expose either patient or technician to potentially harmful radiation. Although the length of time of exposure is relatively short, CT scans still have this risk; there are no known adverse affects to the patient from an MRI scan.

The cost of an MRI scan tends to be higher than for a CT scan, although this can vary according to the patient’s needs.
One reason why a patient might opt for CT is if they have metal implants in their body, since these often mean that an MRI is impossible.

How Much Does a MRI Scan Cost in a Private Hospital?

There are several differing methods of MRI scanning available in the UK both on the NHS and privately. When receiving a quote for MRI scanning patients are advised to ensure that this includes the surgeon’s fee, the consultant radiologist’s fee and the hospital charge for the procedure.

Costs are the same whether an open or closed MRI scanner is being used, however there are several variables in terms of cost.

These include the body part to be examined, the need for contrast/dye injection, whether the scan is to be performed at hospital or outpatient imaging centre and local competition in the region.

Within London for example, especially at Harley Street clinics, the prices can rise considerably.

Outpatient imaging centres usually quote a lower price for MRI scans, as opposed to hospitals. Special discounts on the cost of MRI scan can also be obtained in some instances and some centres or even hospitals may offer a discount payment is received in a single payment.

The Different Types of Scan Available

Body Scans

A body scan performed under private healthcare generally starts at around £200 to £250 per region; these can include elbows, knees or the spine. Many clinics offer packages which allow for multi region scans which offer value for money on multiple scans. These prices are the same for a full abdominal scan.

Brain Scans

Brain scans are similarly priced to body scans, starting in the region of £200, and can rise to around £600 at a top Harley Street clinic in London.

Lung Scans

Prices begin to rise when the major organs are the area being scanned and a lung scan starts at around £300.

Heart Scans

Cardiac scans require far more detail and analysis and this is reflected in a sharp price increase; scans begin at £400 but can be up to £600 in Central London.

Virtual Colonoscopy

The priciest scan available also carries the most convoluted procedure and as a result these tend to start at £550.

Total Body Scan

Several clinics also provide an option for a full body scan which incorporates both CT and MRI scanning. These comprehensive procedures include an MRI scan of the brain and arteries to the brain, the abdomen, pelvis (including prostate for male and uterus and ovaries for female patients) and a CT heart and lungs scan. The cost usually starts at around £1300 but can be much more expensive depending upon the outcome of the scans which may provoke further scans or tests. 

SOURCE of the above CLICK HERE

Summary:

Costs of private MRI Scans

Although MRI scans are widely available through the National Health Service there can be waiting times that vary from weeks to months.

If you need a MRI scan quickly you can choose to have it done privately. Some private medical insurance policies will cover MRI scans so it is best to contact your insurer before booking a private appointment.

There can be an insured cost of between £700 and 1500 for a scan carried out on any single part of the body.

The price will depend on the area to be scanned with a heart scan costing around £400 while places such as Harley Street charge much more.