Medical visualization
- This article should be merged with Medical imaging
Medical visualization is the process by which physicians evaluate an area of the patients body not normally visible for the purpose of diagnosis and treatment.
Traditional Methods
The earliest method of "visualization" is for the physician to palpate (feel) an area of the body to gain a mental idea of the state of the structures below it. This is commonly use to diagnose aortic aneurysms, fractures, enlarged internal organs (e.g liver), and some tumors, as well as many other conditions. The obvious problem with this method is that it is subject to interpretation, and the results cannot be stored except in a written form.
2D Methods of Visualization
Radiographs
Main article: Radiography
Radiographs, more commonly known as x-rays, are often used to determine the type and extent of a fracture. With the use of radioactive dyes, such as barium, they can also be used to visualize the structure of the intestines - this can help diagnose certain types of colon cancer.
Computed Tomography
Main article: Computed axial tomography
A CT scan, also known as a CAT scan (Computed Axial Tomography scan), traditionally produces a 2D image of the stuctures in a small section of the body. It uses radiation, just like radiographs, and thus repeat scans are not reccomended for children.
Magnetic Resonance Imaging
Main article: Magnetic resonance imaging
An MRI uses powerful magnets to excite hydrogen nuclei in water molecules in human tissue, producing a detectable signal. Like a CT scan, an MRI traditionally creates a 2D image of a small "slice" of the body. As an MRI does not use radiation, it is the preferred imaging method for children and pregnant women.
Ultrasound
Main article: Medical ultrasonography
Medical ultrasonography uses high frequency sound waves of between 3.5 to 7.0 megahertz (i.e. 3.5 to 7 million cycles per second) that are reflected by tissue at varying rates to produce a 2D image, traditionally on a TV monitor. This is often used to visualize the fetus in pregnant women. It has a low resolution compared to CT, MRI, and radiographs.
3D Methods of Visualization
Recently, techniques have been developed the enable CT, MRI and Ultrasound scans to produce 3D images for the physician. Traditionally CT and MRI scans produced static output on film. To produce 3D images, many scans are made, then combined by computers to produce a 3D model, which can then be manipulated by the physician. 3D ultrasounds are produced using a somewhat similar technique.
With the ability to visualize important structures in great detail, 3D visualization methods are a valuable resource for the diagnosis and surgical treatment of many pathologies. It was a key resource (and also the cause of failure) for the famous, but ultimately unsuccessful attempt by Singaporean surgeons to separate Iranian twins Ladan and Laleh Bijani in 2003. The 3D equipment was used previously for similar operations with great success.
