1. Introduction
Needle intervention is used in many medical diagnostic and therapeutic procedures, such as drug delivery, biopsy, and anesthesia. In these procedures, accurate navigation of the needle is crucial for the success and safety of the intervention and to improve the patient comfort. Due to the advantages of low cost, non-invasiveness, and real-time capability, ultrasound imaging is commonly used to provide intra-operative images that guide needle insertion to the desired target [1]. However, localizing the needle in ultrasound images is often challenging due to needle reflection of the ultrasound beam away from the transducer, speckle interference pattern that degrades the quality of ultrasound images, and the existence of strong linear structures in the ultrasound images that are similar to the needle [2]–[3].