What type of ultrasound is primarily used for vascular studies?

Doppler ultrasound is specifically designed to evaluate the flow of blood through the vessels, making it the primary choice for vascular studies. This technique uses the Doppler effect to assess changes in frequency of sound waves reflected off moving objects, such as red blood cells. By measuring these changes, Doppler ultrasound provides important information about the direction and speed of blood flow, which is crucial for diagnosing conditions such as blood clots, arterial blockages, and other vascular disorders.

In contrast, diagnostic ultrasound generally refers to a broader category of imaging techniques used for various assessments, including but not limited to the examination of organs and soft tissues, without a specific focus on blood flow. Therapeutic ultrasound is primarily utilized for treatment purposes rather than imaging and diagnosis. 3D ultrasound is a specialized imaging technique that provides three-dimensional images, often used in obstetrics and other applications, but does not specifically focus on vascular studies. Therefore, Doppler ultrasound stands out as the correct answer for vascular evaluations due to its unique capability to assess blood flow dynamics.