Comparison: Imaging Using Different Techniques

The imaging technique that your doctor uses depends on the part of the body being studied and the type of information needed. X-rays show dense tissue, such as bone, most clearly, whereas contrast X-rays provide a clear image of hollow or fluid-filled parts of the body. MRI and CT scanning can provide information about many types of tissue in great detail. An ultrasound scan can assess function by detecting movement, such as blood flow, and radionuclide scanning, such as SPECT and PET, gives detailed information about organ function.

MRI scan

This technique uses radio waves and a magnetic field to produce detailed images, as in this vertical section through the head.

Doppler ultrasound scan

In Doppler scanning, sound waves are used to create an image of blood flow, as in this scan of the blood vessels of the neck, to detect abnormal flow.

Radionuclide scan

This technique measures levels of cell activity to detect an abnormality, such as an area of increased cell activity in this scan of the pelvis.

Ultrasound scan

This type of scan uses sound waves to produce images and is used for imaging fluid-filled structures such as the bladder.


Ordinary X-rays produce two-dimensional images showing dense tissue, such as bone, most clearly. This view of a normal foot clearly shows the bones.

SPECT scan

A form of radionuclide scanning, SPECT produces images that show the function of cells. This brain scan shows the pattern of activity of brain cells.

CT scan

In CT scanning, X-ray beams are used to create detailed cross-sectional images, as in this horizontal section of the upper abdomen.

Contrast X-ray

In contrast X-rays, an opaque substance, such as barium, is introduced into the body to visualize hollow structures such as the colon.


A special contrast X-ray, called an angiogram, can be used to detect an abnormality in a blood vessel, such as this narrowing of a large artery.

From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.

The subjects, conditions and treatments covered in this encyclopaedia are for information only and may not be covered by your insurance product should you make a claim.

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