Modified weighting method for forward-looking ring-annular arrays

Side-looking Intravascular Ultrasound Systems (IVUS) systems provide high r esolution cross-sectional images of vascular structure. However, blood velo city estimation is hampered by the orthogonality of the primary blood flow direction to the imaging plane, and do not image in front of the catheter. A forward-looking aperture would improve the ability to guide interventions and allow Doppler processing for unproved blood speed estimates; however, catheter-based systems delivered over a guide wire limit forward-looking ar ray geometry to annular variations. Unfortunately, the imaging characterist ics of annular arrays are inferior to a full aperture disk. A modified weig hting method for a practical synthetic phased, ring-annular array is presen ted that achieves a transmit-receive aperture and on-axis performance compa rable to a full aperture disk array.