Cardiac (CT Angiography, MRI, and Nuclear) Imaging and Other Modalities

These are noninvasive diagnostic modalities that provide a detailed picture of the tissues and organs in the body.

CT angiography images are used to aid in the detection of coronary artery lesions or peripheral artery obstruction and in any potential threat of a major cardiac event (7). This imaging technique focuses on the cardiac structures and their adjacent vascular bed and can, thus, obviate the need for more invasive procedures.

Cardiac MRI is a helpful modality that can create full images of the beating heart. This entirely noninvasive technique helps the physician study the configuration and performance of the cardiac muscle (8) and is, as such, considered the "gold standard technique" for the assessment of cardiac function. This technique does not use radiation or X-ray, but has a large magnet effect (9).

Nuclear imaging of the heart assesses not only the blood flow in the cardiac muscle but also myocardial function via specific radionuclide dyes. Throughout this method, the physician administers a small quantity of dye into the vein of the patient in order to obtain nuclear images of the blood flow in the cardiac muscle (10).

Carotid imaging is both safe and painless. This imaging modality is FDA-approved and can effectively screen atherosclerosis and risk of myocardial infarction and stroke.

And last but not least among these imaging modalities is the carotid intima-media thickness (CIMT) technique, which is capable of diagnosing the extent of carotid atherosclerotic vascular disease (11).

The majority of these imaging techniques are generally noninvasive; be that as it may, they require the patient's complete immobility to guarantee optimal image quality. Sometimes the patient is restless or is not cooperative due to neurologic problems and, as a result, needs some degree of sedation. Diagnostic procedures such as TTE, electroencephalogram (EEG), and general radiography in some nervous and uncooperative children may require non-pharmacologic interventions, including relaxation and behavioral interventions. These methods are somewhat similar to pharmacologic approaches and may preclude the use of sedation in some children. Nevertheless, some children with significant distress or anxiety who are undergoing these procedures, especially CT and MRI, must receive sedation (6). In settings where the intravenous (IV) infusion of dexmedetomidine , propofol, etomidate, ketamine, or midazolam is not available, other agents (e.g. oral pentobarbital or oral or rectal chloral hydrate) may be safely used (10). Deep sedation is desirable during cardiac imaging, not only in agitated patients, but also to immobility of patients and obtain high-quality images. What is of paramount importance in this regard is excellent interdisciplinary cooperation with a skilled anesthetist and availability of standard hemodynamic monitoring (ECG, pulse oximetry, capnography, and noninvasive blood pressure measurement) as well as intubation and ventilation equipment (7).

In conclusion, the available guidelines on cardiac imaging modalities recommend suitable sedation administered by well-qualified sedation practitioners (1, 3, 11, 12).