A Miniature Forward-Looking Phased-Array Transducer for Interventional Biopsy Guidance

Ultrasound-guided interventional biopsy is becoming an increasingly popular and valuable tool in the clinic. Conventionally, low-frequency (1–5 MHz) ultrasound probes are employed on the patient's body surface for guiding interventional procedures, leading to low imaging resolution and low puncture accuracy. Several efforts have been made to achieve precise punctures, such as inserting a miniaturized high-frequency phased-array transducer into the patient's body. However, the interventional devices (introducer biopsy needles) are all separate from those ultrasound probes, which will cause additional damage and operation complexity. Therefore, in this work, a miniature higher frequency phased-array probe integrated with a 0.4 mm intervention working channel is developed, which had 48 array elements and an outer diameter of only 3 mm. The center frequency and −6 dB bandwidth of this probe are measured as 26.2 MHz and 59.6%, respectively. For evaluating its guiding performance, the wire-phantom, ex vivo tissue, and tissue-mimicking phantom experiments were tested. According to the experiments, the axial imaging resolution and lateral resolution can be calculated as 88 and $278~\mu \text{m}$ at a distance of 2 mm far away, respectively, and the effective detecting depth is 12 mm. All these results show that our proposed ultrasound transducer and method can adapt to the works in high-precision interventional guidance.