A forward-viewing ring-annular array for intravascular ultrasound imaging

We have investigated IVUS array design and image synthesis methods allowing simultaneous sideward imaging at 20MHz and forward imaging at 10MHz. This design is appropriate for over-the-wire delivery but limits the forward-viewing aperture to a ring-annular array. In particular, a 1200/spl mu/m diameter ring-annular array with 64 elements has been constructed. The measured forward-viewing radiation pattern of an individual element indicates an acceptance angle range of over 90/spl deg/. Our beam synthesis involves a total of 210 transceiver firings in a synthetic imaging mode for a given 3D frame. Broadband simulations demonstrated this design can achieve side-lobes under -40dB for on-axis situations and under -30dB for steering to the edge of a 60/spl deg/ cone.