While Ascension's previous 1,8 mm sensor could fit in a larger 7 French catheter, the new tracker is small enough to fit into the distal tip of a 4 French catheter as well as other flexible instruments such as biopsy needles, probes, robotic end-effectors and scopes. As such, it enables an incredible new world of image guided procedures and medical exploration into smaller blood vessels and organs, from the cardiac system and fallopian tubes to bronchial passageways and soft-tissue ducts.
A microBIRD sensor, 1,3 mm in width, can now be used with catheters as small as 4 French on the French Catheter Scale. Previously, sensor size was limited to 1,8 mm for insertion in catheters of 7 French and higher.
"This sensor size reduction is a significant milestone in our developmental roadmap for microBIRD", stated Ascension vice president, Jack Scully. "Now we can offer medical device manufacturers sensors small enough to enable 3D guidance and intrabody navigation in places once inaccessible."
microBIRD's pulsed DC magnetic technology accurately measures the position and orientation of one or more sensors without line-of-sight restriction even in the presence of conductive metals. For minimally invasive medical procedures, microBIRD is often used with an imaging modality and 3D software to continuously report sensor location on a graphical reconstruction of internal anatomy. The resulting roadmap can guide an instrument to a target within the human body. With microBIRD and advanced imaging systems, clinicians can literally "see" inside the human body.
IRLUS, the new medical imaging tool developed by Ascension and CIMIT, stands for Image Registered Laparoscopic Ultrasound System. IRLUS provides a new way to visualize, in 3D, pancreatic and liver landmarks and stage cancers in these organs. Prior to IRLUS, it was difficult for clinicians to use minimally invasive laparoscopic ultrasound to identify pancreatic structures and vessels. Limited acoustic windows and constrained probe movements hampered easy identification. IRLUS solves the problem by combining real-time laparoscopic ultrasound images with pre-operative CT data. The surgeon can now clearly see a 3D rendering of the ultrasound image plane overlaid on a patient's segmented anatomy.
IRLUS consists of a laparoscopic transducer and a surgical pointing device, both of which are tracked in real-time by Ascension's 1,8 mm wide microBIRD sensors and a laptop computer. Visualization software running on the laptop aligns pre-operative CT data with real-time laparoscopic images to provide the physician with spatial cues for correct interpretation of the ultrasound images.
Recent research has shown that IRLUS is a helpful adjunct to many other laparoscopic procedures, increasing the ability of surgeons to correctly identify anatomic landmarks. It also improves the efficiency of traditional ultrasound, by displaying real-time ultrasound images in the context of pre-operative 3D imaging.
The IRLUS system will be exhibited at SAGES, the annual conference of the Society of American Gastrointestinal Endoscopic Surgeons on April 14-17, 2005 in Ft. Lauderdale, Florida. The SAGES conference in 2005 will be co-located with the annual Spring meetings of the American Hepato-Pancreato-Biliary Association (AHPBA) and the American College of Surgeons (ACS). Conference attendees are invited to visit booth number 512 for a hands-on opportunity to experience the IRLUS system.
Ascension will also demonstrate its newest microBIRD feature, a flat transmitter that negates the distorting effects of carbon steel and iron alloys. To date, these distorters have limited the acceptance and use of magnetic guidance devices in medical imaging.
Ascension Technology Corporation, based in Burlington, Vermont, USA, is specialized in DC magnetic guidance and motion tracking solutions for medical applications. For more information about Ascension trackers, you can visit the Ascension Web site or read the VMW March 2005 article Ascension demonstrates latest microBIRD sensor with immunity to ferrous metal distortion.