Radiology: the second 100 years.

• Author: Fishman, Elliot

Now into its second century, radiology still is pursuing the same goal - visualization and treatment of the structures of the human body. Obviously, much has changed since Wilhelm Roentgen discovered the X-ray in his Wurtzberg, Germany, laboratory on Nov. 8, 1895. At that time, he could not have dreamed of the imaging techniques and technology that would follow. Today, radiology has a strong diagnostic armory that includes computed tomography (CT), magnetic resonance imaging (MRI), ultrasound, and nuclear medicine, including positron emission tomography (PET) and single photo emission computer tomography (SPECT) scanning, all available for detecting a wide range of disease processes.

Most of these tools use flat film manufactured specifically for radiology, on which the images appear. The next step forward in diagnosis is visualization of data with three-dimensional imaging. With computers developed for non-medical applications - such as those used for military flight and weapons simulations, 3-D computer animation for movies like "Jurassic Park," and weather forecasting such as hurricane simulations - it is possible to create 3-D images on computer workstations that provide a lifelike model of the patient.

These images can be rotated through any plane or perspective to enable physicians to see various parts of the body. Images may be manipulated to "peel away" organs and isolate a single structure, giving doctors a better look at the area. Stereo goggles can be used to enhance the 3-D depth cues of the image, creating a "pop-out" effect similar to the "Magic Eye" 3-D books and posters that are popular today.

Yet, 3-D images are only useful if they can affect patient care positively. Results from several leading academic institutions show that 3-D imaging of spiral CT data can replace more invasive, and expensive, studies while providing the same information. In addition, earlier diagnosis and more accurate classification of cancers - determining how far a tumor has spread, for instance - an facilitate less costly and more effective treatments.

Three-dimensional imaging has become an important diagnostic tool in part because of better image quality using volume rendering techniques that provide true-to-life, accurate images. Volume rendering uses a computer to reconstruct flat images into three dimensions and can be done in almost "real time." Applications for this technology have included the brain, chest, abdomen, and skeletal system.

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