Brain imaging

MRI, CT, PET - all those acronyms can seem confusing, but never fear! In this gallery we take a tour of some of the common types of imaging used to explore the brain, and to understand the effects things like stroke, Parkinson’s disease and Alzheimer’s disease can have on the brain.

Image research and captions are by Holly Story and are adapted from Wellcome Images unless stated otherwise. For more scientific and medical images, see Wellcome Images.

3T Phillips MRI scanner

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This is a photograph of a 3T MRI scanner. Scanners such as this one use magnetic resonance imaging (MRI) to produce images of a patient’s brain. The letter ‘T’ stands for ‘Tesla’, the unit that indicates the size of the magnetic field used in the scanner. In the past, machines only had a 1.5T magnetic field; now, most new scanners use 3T imaging. The stronger magnetic field improves the image resolution and can increase the speed of imaging.

MRI images can reveal how a brain has been damaged or affected by neurological disease. Doctors can use MRI to diagnose and monitor a variety of different neurological conditions, including Alzheimer’s disease, epilepsy, multiple sclerosis and stroke. In this gallery you will find some examples of images produced from MRI scans, of both healthy and damaged brains.

Credit: Wellcome Library, London.

MRI scanner in use

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This photograph shows a patient coming out of an MRI scanner. The brain scans are displayed on a computer screen in the foreground.

Credit: Wellcome Library, London.

MRI image of a healthy brain

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This is an example of an image produced by an MRI scanner. The scan gives a lateral view of a normal head showing the brain and nasal structures. This is a healthy brain, but the brains in the following slides have both been damaged by stroke: can you see the differences between the images?

Credit: Wellcome Trust Centre for Neuroimaging.

MRI image showing damage to the brain caused by stroke

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This is an MRI image of a brain that has been damaged by a stroke. The damage, in the left temporoparietal cortex, is visible as a dark area on the scan. As a result of this damage, the patient, a 24-year-old woman, was left with debilitating epilepsy and language difficulties. She was unable to speak, read or write and was subject to fits and seizures but has since made a good recovery.

The stroke is likely have been caused by a haemorrhage (bleed) because it encompasses different arterial territories. Evidence of the surgical intervention for the haemorrhage is visible in the disjointed bone at the back of the head.

Credit: Wellcome Trust Centre for Neuroimaging.

MRI image showing damage to the brain caused by stroke

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This is an MRI image of a brain that has been damaged by a stroke. The stroke was caused by a blockage in the left middle cerebral artery. It caused extensive damage to frontal, temporal, parietal and subcortical regions: the damage can be seen in the dark area on the left side of the scan. As a result of this damage, the patient (a 66-year-old man) has difficulty comprehending and producing speech.

Credit: Wellcome Trust Centre for Neuroimaging.

MRI image of a brain showing a pituitary tumour

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This image of a human head was taken with a 3T MRI scanner. The image shows a pituitary tumour as an enlarged mass in the brain of a 48-year-old female patient. MRI scans are often used to diagnose brain tumours and to help locate tumours so they can be accurately removed in surgery. A pituitary tumour is a tumour in the pituitary gland, which is a small oval-shaped gland found at the base of the brain.

Credit: Nuada Medical , Wellcome Images.

A healthy brain and a brain affected by Alzheimer’s disease

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This slide shows 3T MRI scans of two different brains. The scan on the left is from a patient with Alzheimer’s disease. It shows prominent brain shrinkage, and the associated expansion of the ventricular system (the black region at the centre of the image), compared to the healthy control scan on the right. MRI images like these can be used to diagnose Alzheimer’s disease and monitor the progress of the disease.

Credit: Dementia Research Centre, UCL.

Atrophy caused by Alzheimer’s disease

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Researchers are using MRI to investigate how Alzheimer’s disease spreads through the brain. These figures have been generated from a series of MRI scans of the brains of a group of people with Alzheimer’s disease. They show where atrophy (the shrinkage or degeneration caused by the disease) has occurred in the insular cortex and temporal lobe.

Credit: Figures created by Ged Ridgway, UCL, using MR images from the MIRIAD project (miriad.drc.ion.ucl.ac.uk).

Cut-away fMRI of a healthy brain showing the visual cortex

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This cut-away image of a brain has been created using functional magnetic resonance imaging (fMRI) scans of a healthy human brain. Functional MRI is a form of MRI used to show which parts of the brain become active during different mental processes. In this case, the image shows activity in the visual cortex, which is highlighted in yellow at the back of the brain.

Credit: Mark Lythgoe and Chloe Hutton, Wellcome Images.

A CT scanner in use

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This photograph shows a CT scanner in use. A nurse attends to the patient while the radiographer enters patient data and monitors progress on the computer. ‘CT’ stands for computerised tomography. This type of scanner uses X-rays and a computer to produce detailed images of slices through the body and brain. It is widely used in hospitals to diagnose and monitor a variety of conditions, including brain tumours and injuries to the bones and internal organs.

Credit: Justine Desmond, Wellcome Images.

CT scan showing a pituitary tumour

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This is a CT scan showing a pituitary tumour in the brain. Compare this to the MRI image of a similar tumour that appeared earlier in the gallery: how are they different?

The CT scan uses X-rays to produce images of the head, so hard tissues, such as the bone of the skull, show up clearly in white. In the MRI image, the bone of the skull appears as a dark area in the scan and soft tissue (such as the brain) is shown more clearly.

Credit: Wellcome Library, London.

A PET scanner in use

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This is a photograph of a positron emission tomography (PET) scanner with a patient and technician operator. PET imaging can be used to measure the levels of neurotransmitters, their receptors, and their transporters. Before the scan the patient is injected with a radioactive ‘tracer’ substance that binds to a certain molecule. When the patient is scanned, the PET scanner detects the radioactive signal emitted by the tracer. The intensity of the signal indicates the level of the molecule in different areas of the brain. PET scans can be used to monitor a range of neurological conditions, including Parkinson’s disease, Alzheimer’s disease and depression.

Credit: Wellcome Library, London.

Colour-enhanced PET scan of the basal ganglia

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This image shows a PET scan of the basal ganglia of a healthy brain. In this case, the scan has been enhanced with colour.

Credit: Wellcome Library, London.