Cardiac CT Scan (Heart)

Thursday, December 8, 2016


Coronary Angiography CT Scan

   For years coronary angiography provides the only method of imaging of the coronary arteries. Although coronary angiography is a useful tool, it is an invasive and associated with a small and  although not insignificant risk of complications, including stroke, bleeding severe enough to require transfusion, vascular access complications, myocardial infarction and even death. Coronary angiography procedure is associated with significant costs associated with personnel, equipment, and the additional cost related to the recovery time needed after arterial catheter removal, as well as the management of possible adverse events. For these reasons, coronary angiography is typically reserved for patients with serious symptoms and a high likelihood of having significant coronary artery disease, such as chest pain or after a stress test with positive medical results.

Use of Advance CT scan and MR Imaging

   The advancement of CT and MR imaging technology are changing established practices. Cardiac CT has emerged as a less invasive imaging modality for the diagnosis of Coronary Artery Disease (CAD) and is often used to avoid coronary angiography in low and intermediate risk to patients, in particular. Continuous improvements in CT detector technology and in temporal (speed) and spatial or thin slices resolution have resulted in clinical results with cardiac CT that are similar to those obtainable with conventional catheter coronary angiography. Cardiac CT scan can provide not only anatomic information, but also functional information to aid in the diagnosis and treatment of cardiovascular disease.

Contrast Administration Cardia CT Scan

   Most cardiac CT protocols require the IV administration of iodinated contrast media. Standard screening for contraindication to the contras agents, like renal imapairment, and iodine allergy is necessary. An intravenous line is placed using a large lumen at about 20 gauge or larger, flexible cannula in a vein of sufficient diameter to accommodate a relatively high injection rate. 
Typically the antecubital vein is used, preferably on the right side. Hand veins are not oftenly use because they are usually too small, but when this vein is use, the delay time between injection and the start of the scan should be adjusted.

Contrast Media Use in Cardiac CT

   Contrast agents use in cardiac CT is a low osmolar or isomolar, nonionic agent with a iodine concentration between 300 and 400 mg / mL is injected. An injection rate between 3 to 6 mL per second. With such rapid injection rates, radiologic technologist must be particularly vigilant in guarding against contrast extravasation. The volume of contrast agent used per examination varies from 70 to 150 mL, depending on the scan protocol, the scanner type used, and the patient’s weight.

cardiac ct scan
The layers of the heart are identified by
arrows on the cross-sectional CT slice. Image courtesy of the
University of Michigan.

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