Scan Of Kidneys

Colour image

Counterbalance

Area of high brain activity

PET scan of normal brain

In this cross section of the brain, the yellow and red patches are highly active areas and the blue and black patches are less active areas.

Area of high brain activity

PET and SPECT scanning

Positron emission tomography (PET) and single-photon-emission computerized tomography (SPECT) are forms of radionuclide scanning (p.41). In both, a radionuclide (radioactive substance) is introduced into the body and taken up by tissues, and the radiation emitted is detected by a scanner. PET uses a radionuclide attached to glucose or other molecules essential to cell metabolism and can show the functioning of individual cells within tissues. It is mainly used to assess the heart and the brain. SPECT uses radionuclides that emit photons (a form of energy), whose movements can be traced by the scanner. The technique can show blood flow within organs and is used to assess if they are functioning normally. SPECT is chiefly used to assess the brain, heart, liver, and lungs.

Endoscopy

Endoscopy is a procedure in which a doctor views internal structures using a tube-like instrument called an endoscope, which includes a fibreoptic light source and magnifying lenses. The tip of the endoscope is passed through a natural body opening, such as the mouth, or a small incision in the skin. A rigid or flexible endoscope may be used, depending on the area to be examined. The view may be seen directly through an eyepiece or shown on a monitor. Endoscopy may be used for diagnosis or for treatments.

Area of loiv brain activity

PET scan of normal brain

In this cross section of the brain, the yellow and red patches are highly active areas and the blue and black patches are less active areas.

Flexible endoscopes

A flexible endoscope has a long, thin tube that can be steered round bends in internal passages, such as the oesophagus and the colon, and enter deep into the body. These endoscopes are often used for viewing inside the digestive and respiratory tracts. The instrument is inserted through a natural opening such as the mouth or anus; the person undergoing the procedure is first given a sedative or a local anaesthetic, for example, sprayed on to the back of the throat. The endoscope incorporates a system of lights, lenses, and optical fibres, and usually a video camera at the tip, allowing the doctor to view structures either directly through an eyepiece or on a video screen. If procedures, such as taking tissue samples, need to be carried out, very fine instruments can be passed down the tube, and the doctor can use the view from the tip as a guide during the procedure. The view may be recorded on videotape.

Endoscope

Upper digestive tract endoscopy

Before the procedure, you may be given a sedative. The endoscope is then passed into the body through the mouth. The view from the tip of the endoscope allows the doctor to detect abnormalities in the lining of the digestive tract.

Blood pressure cuff

Site of sedative injection

Endoscope

Upper digestive tract endoscopy

Before the procedure, you may be given a sedative. The endoscope is then passed into the body through the mouth. The view from the tip of the endoscope allows the doctor to detect abnormalities in the lining of the digestive tract.

Oesophagus

Stomach

Tip of endoscope in duodenum

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