The history of cardiac imaging is short, and perhaps, not all that sweet. The gold standard of cardiac imaging is, of course, angiography. Stephen Koch, M.D., medical director and radiologist of Imaging for Life and Imaging Heart (New York City and White Plains, N.Y.), recalls, “Until electron beam CT (EBCT), angiography was the only way to look at cardiac anatomy and coronary images. X-ray isn’t fast enough to freeze the heart.” Still, there are limitations to EBCT technology.

The EBCT cannot replicate the “mA” technique that is one of two parameters necessary to generate the electron beam. This limits the maximum energy that the x-ray has and translates into how the actual image looks. If the patient is large, the signal to noise ratio is very low and the picture is harder to interpret. If the tech attempts to adjust the mA in EBCT, then the number of images that can be taken is affected. Sensation 16 avoids this problem because both the mA and kVP can be adjusted independently (without affecting the number of images) to image the largest patients.

Thus 16-slice technology and Siemens Medical Solutions (Iselin, N.J.) Sensation 16 CT scanner has flung open the door to noninvasive cardiac imaging. Koch explains, “The objective is retrospective reconstruction of cardiac arteries and coronary arteries. With cardiac gating we can tell the computer where in the patient’s ECG we want to image the heart.” Because Sensation 16 takes images every 100 to 250 milliseconds, radiologists can capture the heart during the flat line of the EKG to minimize motion and radiologists and cardiologists can look at any artery in the body without an angiogram.

Cardiac imaging with Sensation 16 represents a stark contrast to angiography. The pre-Sensation 16 picture of cardiac imaging may appear a bit inefficient. Consider a fairly typical cardiac patient. He may have chest pain, high cholesterol or a suspicious family history. The cardiologist orders a stress test. And if the test is normal or equivocal, the next step is angiography. Koch reports, “One-third to one-half of all angiograms are simply for diagnosis. The vast majority are normal.” Nevertheless an angiogram, the gold standard in coronary imaging, is an interventional procedure that can result in complications for the patient.

Please refer to the December 2002 issue for the complete story. For information on article reprints, contact Martin St. Denis