A distorted sensation based on misinterpretation of a real stimulus (for example, a pen is seen as a dagger). It is differs from a hallucination, in which a perception occurs without any stimulus.Usually, illusions are brief and can be understood when explained. They may be due to tiredness or anxiety, to drugs, or to forms of brain damage. Delirium tremens is a classic inducer of illusions. imaging techniques Techniques that produce images of structures within the body. The most commonly used and simplest techniques are X-rays (to view dense structures such as bone) and contrast X-rays, in which a medium, such as barium, that is opaque to X-rays is introduced into the body. Contrast X-ray techniques include barium X-ray examinations (used to examine the oesophagus, the stomach and the small intestine); cholecystography (used to visualize the gallbladder and common bile duct); bronchography (to view the airways connecting the windpipe to the lungs); angiography and venography (to provide images of the blood vessels); intravenous urography (to visualize the kidneys and urinary tract); and ERCP (by which the pancreatic duct and biliary system are examined).
Many X-ray imaging techniques have been superseded by newer procedures. These include ultrasound scanning, MRI (magnetic resonance imaging), PET scanning, and radionuclide scanning. However, X-rays are used in CT scanning. Some of these techniques use computers to process the raw imaging data and produce the actual image. Others can produce images without a computer, although one may be used to enhance the image. imipramine A tricyclic antidepressant drug most commonly used as a longterm treatment for depression. Possible adverse effects include excessive sweating, blurred vision, dizziness, dry mouth, constipation, nausea, and, in older men, difficulty passing urine.
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