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We designed, fabricated, and tested ring annular capacitive micromachined ultrasonic transducer (CMUT) arrays for forward looking intravascular ultrasound (IVUS) imaging in the 10-20MHz range. Our fabrication process uses low stress plasma enhanced chemical vapor deposition (PECVD) to form the silicon nitride membrane and provides localized vacuum sealing. The CMUT fabrication requires a maximum process temperature of 250°C enabling post-CMOS CMUT fabrication for electronics integration. Electrical and acoustic characterization results show that the process is repeatable and the response of 40 × 120μm CMUT elements of a lmm diameter array are suitable for IVUS imaging around 16MHz. We also present initial volumetric imaging experiments on different targets using a 32 element CMUT-based forward looking IVUS array and synthetic aperture image reconstruction techniques.