The traditional evaluation of the patient includes the history and physical examination and a well-planned set of diagnostic tests, often including imaging. Dramatic advances in imaging not only supplement the physical examination, but also now may begin to substitute for part of it.
Medical imaging provides an approach for dividing patients into patients who have an acute compared with a chronic medical problem and patients who have an anatomic compared with a "biochemical" illness. These determinations are crucial for prompt and effective medical and surgical therapy.
[...] STAGING OF ONCOLOGIC DISEASES Diagnostic imaging is a principal method for presurgical staging of neoplastic disease and is essential for evaluating the response to therapy and long-term surveillance. Extent of the primary tumor, invasion or encasement of adjacent structures, presence of regional or distant lymphadenopathy, and distant metastases can be evaluated by cross-sectional imaging with great accuracy. PET is highly sensitive but nonspecific for neoplastic disease. The search for an unknown primary tumor in the presence of metastatic disease is challenging ( Chapter 210 With the advent of MRI and high-resolution multislice CT, more than 50% of initially unknown primary tumors now can be found. [...]
[...] Images are created based on the time delay and intensity of echos returned from tissue after a short pulse of ultrasonic energy, emitted and received by a transducer held in contact with the body. Ultrasound is nonionizing radiation and considered safe for the unborn fetus and other sensitive tissues. With appropriate instrumentation, it is possible to create "tomographic" or slice images, with real-time motion, of body parts if the path of the sound does not hit gas or bone, both of which severely attenuate the sound. [...]
[...] Two limitations of this technology are that the isotope currently has to be produced in a cyclotron, a device that requires expensive construction for radiation safety, and the isotopes are short-lived few hours), requiring proximity to a cyclotron. ANGIOGRAPHY AND INTERVENTIONAL RADIOLOGY Angiography, the imaging of blood vessels, remains at the focus of the field of vascular and interventional radiology and cardiology. Images are achieved by placing a small, steerable catheter within the arterial or venous system, usually by way of a needle puncture of the femoral artery or vein. [...]
[...] At least three other imaging choices exist: no imaging study, a plain radiographic series of the abdomen (technically and economically similar to the chest radiograph but generally not as useful), and MRI of the abdomen or pelvis (usually reserved for more complex situations or after failure to diagnose with other methods). Other than identifying free intraperitoneal air (perforated viscus), gas patterns of bowel obstruction, and radiodense ureteral calculi, the traditional abdominal series, although the least expensive test, is considered generally inferior to CT and has been largely replaced by CT. [...]
[...] The structures of the mediastinum (heart and great vessels, including the pulmonary hila) form distinct tissue density contours outlined by the minimally attenuating lungs; the bony thorax also can be visualized. The same physical facts that make the chest radiograph of such high diagnostic value also cause the plain films of the abdomen to be less so. As a result, CT has nearly totally replaced the plain film of the abdomen. ULTRASOUND Medical ultrasound imaging grew out of the SONAR (SOnic Navigation And Ranging) technology developed during World War II for submarine warfare. [...]
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