5A-2 Two Dimensional Arrays for Real Time 3D Intracranial Imaging of the Brain

We have described and fabricated 2D array transducers for many real time volumetric imaging applications. These applications include transducers operating up to 5 MHz for transthoracic imaging, up to 15 MHz for intracardiac echocardiography (ICE), 5 MHz for transesophageal echocardiography (TEE) and 7 MHz for laparoscopic ultrasound imaging (LUS). We have recently adapted a transducer designed for TEE to be used for real time volumetric endoscopic imaging of the brain. The transducer consists of a 36 times 36 array with an interelement spacing of 0.18 mm. There are 508 transmitting and 256 receive channels placed in a regular pattern in the array. The operating frequency is 5 MHz with a -6 dB bandwidth of 30%. The transducer is fabricated on a 10 layer flexible circuit from MicroConnex (Seattle, WA). We bent the flexible circuit such that the finished transducer is in the forward viewing configuration. We used the Volumetrics Imaging (Durham, NC) 3D scanner to obtain our images in a canine model. In an intra-operative surgical procedure, a 10 mm burr hole was drilled through the skull of the canine. The hole was placed to one side of the midline and the transducer was placed up against the dura for endoscopic ultrasound imaging. Images of the lateral ventricles were produced , including real time 3D guidance of a needle puncture of one ventricle. In addition, contrast (Optison, Amersham) enhanced 3D Doppler color flow images have been made of the cerebral vessels including the complete Circle of Willis. Applications include real time 3D guidance of cerebral spinal fluid extraction from the lateral ventricles and bedside evaluation of critically ill patients where CT and MR imaging techniques are unavailable