15 MHz single element ultrasound needle transducers for neurosurgical applications

Image-guided surgery is today considered to be of significant importance in neurosurgical applications. However, one of its major shortcomings is its reliance on preoperative image data, which does not account for the intraoperative brain deformations and displacements that occur during surgery. In this work, we propose to tackle this issue with the incorporation of an ultrasound device within a biopsy needle that is commonly used as an interventional tool so as to provide immediate feedback to neurosurgeons during surgical procedures. In order to identify the most appropriate path to access a targeted tissue site, needle single element transducers that look both forwards and sideways have been designed and fabricated. Monolithic PZT plates and micro-moulded 1-3 piezocomposites have been adopted as the active materials for feasibility tests. Impedance analysis and pulse-echo testing have been carried out, demonstrating the functionality of the transducers at frequencies of ∼15 MHz. The imaging capabilities of these transducers have been studied by wire phantom scans. Variations in the transducer properties as a result of the use of different active materials are discussed.