The present invention relates to a new intravascular imaging device based on a Shape Memory Alloy (SMA) actuator mechanism embedded inside an elongate member such as a guide wire or catheter. The present invention utilizes a novel SMA mechanism to provide side-looking imaging by providing movement for an ultrasound transducer element. This novel SMA actuator mechanism can be easily fabricated in micro-scale, providing an advantage over existing imaging devices because it offers the ability to miniaturize the overall size of the device, while the use of multiple transducer crystals maximizes field of view. Also disclosed are methods of using the same.