TABLE 1.3 CONTINUED Common Medical Imaging Procedures COMPUTED TOMOGRAPHY (CT) fomerly called computerized acial tomognphy (CAT) scanning] MAGNETIC RESONANCE IMAGING (MRI) Procedure: The body is exposed to a high-energy magetic neld, which causes protons (umall positive paticles within aloms, such as hydrogen) in Procedure: In this fom of computer-asted radiography, anx-ray beam traces an arc at mukiple angles around a section of the body. The resulting body fluids and ticues to amange themselves in relation to the fneld. Then apulse of radio waves "reads" these ion pattems, and a color-coded image is assembled oa a video monitor. The result is a two- or three-dmensional bluepriat of cellular chemutry. transverse section of the body, called a CT ra, is shown on a video monitor. Comments Veualizes soft tssues and organs with much more detail than convertional radiographs. Differing üssue densides show up as varikus shades of gny. Multiple scas can be assembled to build three- dimensional views of structures (descrited next, Whole-tody CT scaming typically targets the torso and appears to provide the maet benefit in screening for lung cancers, coromary artery disease, and kidney cancers. Commens: Relavely safe but camot te used on patients with metal in their bodies. Shows fme details for soft tissues but not for bones. Most useful for differentiating between nonmal and ataommul tissues Used to detect tumocs and artery-clogging fatty plaques reveal brain abnomalties; measure blood fow, and detect a variety of musculoskeletal, liver, and kidhey disorders ANTERIOA Heart Aorta Verlebra Lett rib POSTERICA Magnalic resonance Image of brain in sagital section Computed tomography scan of thorax h inferior view ULTRASOUND SCANNING Procedure: High-frequency sound waves produced by a handheld wand reflect off tody ússues and are detected by the same instrument. The image, which may be still or moving, is calleda onogram (SCN-0-gram) and is shown on a video monitor. Forohead Commens: Safe, mnimasive, painless, and wes ao dyes. Most commonly zed to visualize the fetus during prepnancy. Also used to observe the siee, location, and actions of organs and blood flow through blood vessels (Doppker ultrasound) Eye Наnd Sonogram of fetus (Courtesy of Andrew Joceph Tortora and Damaris Soler) CORONARY (CARDIAC) COMPUTED TOMOGRAPHY ANGIOGRAPHY (CCTA) SCAN POSITRON EMISSION TOMOGRAPHY (PET) Proceture: A substance that emiki positrom (posilively charged particles) is injected into the body, where k is taken up by tssues. The collision of posirons with egaively charged electrors in body tieues produces ganma rays (similar to x-rays) that are detected by gamma cameras positioned around the sutject. A computer receives sigmis from the gamma cameras and comtucts 1 PET scan image, displayed in color on a video monitor. The PET scan shows where the injecled substance is being used in the body. In the PET scan image shown here, the: black and Nue colors ndicate minimal activily; the red orange, yellow, and white colors indicate area of increasingly greater activity. Procedure: In this form of computer-1ssisted radiography, an iodne- containing contrast medum is injected into a vein and a teu-blocker is given to decrease heart rate. Then, aumerouw x-cay beams trace an an around the heat and a scanner detects the x-cay beams and transmits them to a computer, which transfonms the information into a thres-dmensional image of the coronary blood vessels on a monitor. The image produced is called a CCTA Can and can be generaled in leu than 20 seconds. Cawens: Ued primarily to delermine if there re any coronary ariery blockages (for example, alteroscleroic plaque or calcium) that may require in intervention such as angioplasty or stent. The CCTA scan can be rotated, enlarged, and moved at any angle. The procedurecan take thousands of images of the heart within the üme of a singke heartbeat, so * provides a great amount of detail about the heart's structure and function. CouNens: Used to study the physiology of body structures, such as metabolium in the brain or beart. ANTERIOA Nomal len coronary ariery Elockad right coronary ariery POSTERIOA CTA scan of coronary arnarles Postron embskon tomography scan of transverse section of brain (drcied area at upper lett indikates where a stroke has cocumed) ENDOSCOPY Procedure: Endcscopy involves the visual examination of the inside of body organs orcavites using 1 lighted instrument with lerses called an endoscope. The image is viewed through an eyepiece on the endoscope or projected onto a moniior. Conwents: Examples include colonascopy (Eed to examine the interior of the colon, which is part of the large intestine, iaparascopy (sed to examine the organs wthin the abdominopelvie cavity), and arthrascopy (sed to examine the interior ofa joint, usually the knee). Interkor vlew of colon as shown by coloncecopy TABLE 1.3 CONTINUES