Ultrasound Guidance in Interventional Radiology

All interventional procedures start with a needle puncture, whether to catheterize a vessel, access a fluid collection, or biopsy a mass. Fluoroscopy and CT were the earliest imaging techniques used for guidance of needle placement in interventional radiologic procedures. But during the past two decades, ultrasound (US) became the preferred, first-line modality in biopsies and an indispensable adjunct for many other procedures. Even more recently, CT fluoroscopy and MR guidance have joined the repertoire of modalities, although their availability is more limited. Both fluoroscopy and US have the advantage over standard CT of real-time imaging of a needle tip. Computed tomography fluoroscopy can image a needle in real-time, but this technique is associated with a higher radiation dose to the operator's hands. The advantages of US over fluoroscopy, CT, and CT fluoroscopy include the lack of ionizing radiation, portability, and the ability to visualize and avoid blood vessels without intravascular contrast material. Ultrasound guidance also is quicker and less expensive than CT guidance.1