Ascension to show magnetic sensors for new biopsy needle and bronchoscope procedures at RSNA 2008

Burlington 10 November 2008Ascension Technology Corporation will showcase its newest sub-millimeter sensors for localization and guidance of biopsy needles, catheters, and guidewires at RSNA 2008, the Radiological Society of North America Conference and Exposition in Chicago, Illinois, November 30 - December 5, 2008. In addition, CIVCO Medical Solutions and Ascension Technology Corporation have launched a new biopsy needle localization and guidance system for minimally invasive medical procedures. When integrated with 3D ultrasound visualization tools it enables accurate, percutaneous targeting to lesions without radiation or open surgery.


The company's 3D Guidance medSAFE tracker now supports the world's smallest six degrees-of-freedom sensors, 0,9 mm in diameter. This dimension accommodates tip localization of hollow needles as small as 19 gauge and catheters as small as 3 French. Key advantages include: inconspicuous guidance of surgical instruments, environmental immunity, and fast, simultaneous tracking of multiple sensors.

At RSNA, Ascension will show the new sensor in two groundbreaking medical procedures:

  • Percutaneous guidance of a biopsy needle to soft tissue lesions
  • Navigation of a bronchoscope guidewire to deep lung lesions

For the biopsy procedure, a 0,9 mm sensor is embedded in the tip of a hollow needle with a second 8 mm sensor attached to an ultrasound scanhead. Simultaneous tracking of the needle and the ultrasound scan planes enables live 3D guidance from the needle's puncture path to an internal lesion. Visualization software superimposes a trajectory path on the ultrasound imagery to show advancement of the needle towards the target. The sensor can similarly be used for percutaneous 3D guidance, referenced to markers on pre-acquired images, such as CT or MRI. It can also be used to fuse pre-operative and ultrasound images together for improved procedural vision, patient gating, and navigation of needles and probes.

Ascension's newest medSAFE sensor is 0,90 mm in diameter and weighs less than one-tenth gram. It freely fits into the tip of a hollow 19-gauge needle, which can be rapidly tracked in all six degrees of freedom. Besides monitoring needle and guidewire location, the new sensor with imaging software provides immediate feedback of a successful intervention without over reliance on X-rays.

For the bronchoscope procedure, VIDA Diagnostics will be in the Ascension booth to show its DC magnetic navigation system for bronchoscopy. Its system includes a 0,9 mm magnetic sensor attached to the distal tip of the guidewire of an Olympus bronchoscope. 3D tracking enables clinicians to accurately navigate tools to deep lung lesions for diagnostic and therapeutic purposes. The system combines VIDA's proprietary lung mapping and modeling technology, referenced to pre-acquired CT scans, for real-time, interventional guidance to previously inaccessible lung regions.

medSAFE 0,9 mm sensor is seen protruding from the guidewire of the Olympus bronchoscope. VIDA Diagnostics has developed a pulmonary workstation.

3D Guidance medSAFE fully meets electrical safety regulations. Measurements are unaffected when tracking in close proximity to intravascular ultrasound arrays, composite beds, low frequency noise sources, and common hospital metals, such as 300-series stainless steels, titanium, and aluminum. When used with its flat magnetic field generator, 3D Guidance medSAFE measurements are immune from ferromagnetic metals beneath its planar surface, such as structural members in OR and procedural tables.

CIVCO has designed a proprietary tracking needle with a protective reusable housing for the six degrees-of-freedom (6DOF) sensor. Combined with the Ascension sensor technology, the needle allows simultaneous tracking of the distal tip of the needle and the ultrasound scan planes allowing clinicians to visualize the necessary patient anatomy as well as the position of the needle tip in real-time.

Ultrasound imaging alone cannot always guarantee the tip of a needle or the electrodes of an ablation probe will hit the centre of a three-dimensional lesion - especially a small one. The new approach takes the estimation and inconsistencies out of ultrasound-assisted biopsy and RF ablation by instantly tracking both the 3D location of the ultrasound transducer and the tip of the needle. If pre-operative imaging is indicated for selecting the best interventional path or for comparing the results of different imaging modalities, the sensor aligns the real-time ultrasound image with the pre-operative image in a process called image fusion.

Procedurally, the sensor's real-time spatial data is graphically overlaid on video images of the B-scan plane. The clinician can then monitor the real-time trajectory of the needle through delicate anatomy of the geometric centre of an internal target, such as a tumour, cyst or polyp. This process clearly visualizes the location of the needle - either "in" or "out" of plane - for either a longitudinal or transverse approach.

Even before the skin is punctured, the system registers the biopsy needle to the centre of the target, predicting the path of the needle while avoiding other anatomical structures. As the needle advances towards the target, the fused images provide real-time feedback as the path to be taken. Once optimally positioned, the needle can be rotated to a perpendicular plane to provide three-dimensional verification that the tip is on target. Targets can also be marked and mapped for follow-up.


This year's RSNA conference will be held at Chicago's McCormick Place. 3D Guidance medSAFE will be shown in Booth no. 7910, North Building, Hall B. Ascension Technology Corporation, based in Burlington, Vermont, USA, is a world expert in magnetic guidance and localization solutions for medical navigation. More information about Ascension is available at the Ascension website or in the VMW November 2008 article National Cancer Institute awards Ascension SBIR Grant to support cancer intervention.

Leslie Versweyveld

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