No practicing lawyer will remember extensive, detailed information about all the testing modalities that appear in the title of this article. Please do not expect coverage of the field; however; understanding the broad ambit of what can be tested may motivate you to look this material up in specific cases, and become as expert as the expert on the narrow issues of your case when your client’s medical problem falls into one of the listed categories. The better you understand the medical/physical/physiological facts of your case, the less of an advantage an expert has.
The starting of successful business development is a fascinating one, in which individual techniques have been pushed to their apparent physical and physiological limits, only to be advanced further by seemingly unrelated developments, like the advent of computers, the advanced use of contrast materials, the use of modalities unrelated to X-irradiation, like ultrasound and the properties’ intra-atomic particles as they are moved in and out of orbit by magnets, by combining a technician’s hands-on leadership, and the use of scans to light up portions of the brain by virtue of their metabolic activity and use of glucose, physicians can successfully study an MRI.
Plain films, the only radiographic testing widely available from the start of the 20th century through the ’60s or so, carried substantial interpretive defects. With a single film, it was not easy to tell what was in front and what was in back, and any single view was of superimposed structures. Also, the structures closest to the X-ray beam were magnified slightly compared with structures further away, making exact interpretation a bit more difficult and risk the business growing too fast.
PA and lateral films, giving frontal and side views, helped separate what was in front from what was in back, but still gave views, in each direction, of superimposed structures, making fine distinctions and analysis of borders difficult.
At some point in the ’60s, radiologists discovered that by moving two plates in opposite directions as an X-ray was taken, the resulting film was very fuzzy except in one narrow plane. This one plane, less than an inch in depth, came out in sharp focus, without the “superimposition” artifacts of plain films and permitted clearer delineation of anatomy within that thin plane. The use of moving plates made everything but the one plane so visually fuzzy it could be ignored. This sharp slice was called a “tomogram.”
Radiologists, at some trouble and considerable expense from issuing a subpoena, began setting up their instruments to do a series of such tomograms, giving approximate slices coming into focus through an organ: “serial tomograms” as these were called.
Computerized tomography, and later MRI
With the advent of computers, radiologists became able to obtain virtually an infinite number of “tomograms”, taken not just on front to back and side to side views, but at multiple angles around the patient, and to synthesize pictures from multiple, narrow planes of the body. Permitting very precise anatomic definitions of organs or abnormal structures.
Recently, much faster CT machines, which look at the body extremely rapidly and from multiple directions, called “helical” CT because of the wave-like direction the viewing aperture took, have been developed. Some of these are so rapid that they may take multiple images from different directions so quickly that you can see the full three-dimensional anatomy of the heart virtually stopped in mid-beat.
CT remains a procedure of choice for specific illnesses, like pulmonary emboli, bony abnormalities, and acute appendicitis, and remains a less expensive, less unwieldy apparatus than MRIs and is routinely used as a “guiding”, modality for biopsies and drainages of internal organs.
Non X-ray modalities of visualizing structure
Other means of visualizing anatomy were developed, partly because some tissues that health-care providers wanted to discriminate and view as separate were very similar in radiographic density, hence were hard to separate with X-rays alone, even CTs and because there was concern about the amount of radiation delivered when multiple X-rays were needed for computer synthesis of an image.
Ultrasound essentially applied the principles of radar to the human body, with different organs reflecting sound waves differently, permitting a new form of imaging, which was far less expensive than CT imaging, and could be obtained with portable, even bedside instruments. Organs or structures that might be radiographically of similar density might have altogether different properties of reflection of sound, making the ultrasound an alternative method of visualization.
Ultrasound remains a procedure of choice for bedside diagnosis of phlebitis or peripheral circulatory abnormalities, the diagnosis of gallstones, and the differential diagnosis of lesions in breast, kidney, intra-abdominal masses and abnormalities in other organs where it is important to discriminate between solid and cystic structures.
Disturbing the atom: Magnetic Resonancy Imaging (MRI)
Beginning in the late ’70s and early ’80s, it became clear that pictures could be obtained on plates if magnetic fields were applied to organs. These magnetic fields moved electrons in the atoms of these organs slightly out of orbit. The electrons returned to their normal orbit when the magnetic field was altered, releasing a form of energy that created an image on suitable plates. Adjacent organs or portions of organs that may have the same radiographic density, hence be only vaguely separable using Xrays, including CT scans, may be very different in their reaction to a magnetic beam. MRls, with multiple views also synthesized by computers into constructs that look very much like slices from an anatomy text, have become the “gold standard” for many tissue analyses. MRI is generally regarded as superior to CT scan for soft tissue problems, as CT is superior to MRI for bone problems. Most Current technologies give the viewer not a single picture but a computerized synthesis of what many pictures show, from which the viewer “deduces” what is true.