Role of Ultrasound

Ultrasound not only complements the more traditional approaches such as x-ray, but also possesses unique characteristics that are advantageous in comparison to other competing modalities such as x-ray computed tomography (CT), radionuclide emission tomography, and magnetic resonance imaging (MRI). More specifically:

• Ultrasound is a form of nonionizing radiation and is considered safe to the best of present knowledge.
• It is less expensive than imaging modalities of similar capabilities.
• It produces images in real time, unattainable at the present time by any other methods.
• It has a resolution in the millimeter range for the frequencies being clinically used today, which may be improved if the frequency is increased.
• It can yield blood flow information by applying the Doppler principle.
• It is portable and thus can be easily transported to the bedside of a patient. Ultrasound also has several drawbacks. Chief among them are:
• Organs containing gases and bony structures cannot be adequately imaged without introducing specialized procedures.
• Only a limited window is available for ultrasonic examination of certain organs, such as heart and neonatal brain.
• It depends on operator skill.
• It is sometimes impossible to obtain good images from certain types of patients, including obese patients.

The many advantages that ultrasound can offer have enabled it to become a valuable diagnostic tool in such medical disciplines as cardiology, obstetrics, gynecology, surgery, pediatrics, radiology, and neurology, to name just a few. The relationship among ultrasound and other imaging modalities is a dynamic one. Ultrasound is the tool of choice in obstetrics primarily because of its noninvasive nature, its cost-effectiveness, and its real-time imaging capability. This role will not change in the foreseeable future. Ultrasound also enjoys similar success in cardiology, demonstrated by the fact that echocardiography is a training that every cardiologist must have. The future of ultrasound in cardiology, however, is not as rosy as in obstetrics because, as ultrasound progresses at a rapid rate, other competing imaging