Development of ultrasonically marked needle for ultrasonically guided biopsy

It has been shown that the chances of having complications during biopsy is greatly reduced when the procedure is guided by ultrasound. However, because of the specular nature of echoes reflected by the needle, the needle tip is sometimes difficult to visualize on the ultrasound image. A number of methods have been studied to aid in the localization of the needle tip. Among them is a method by I. Cikes and B. Breyer (1984) which used a PZT crystal mounted on a catheter tip as either a passive ultrasound receiver or an active ultrasound transmitter to mark the position of the catheter tip in echocardiographically guided cardiac catheterization. This method was investigated experimentally using a piezoelectric polymer, PVDF, to mark the position of the tip of the biopsy needle. The advantage of PVDF over PZT is that it is thin, flexible, and wideband. PVDF-mounted needles have been fabricated and ultrasonically evaluated in water bath and in tissue-mimicking phantoms. Results are reported to demonstrate the feasibility of the approach and to elucidate design considerations that need to be addressed to make the device a useful clinical tool