Tools Highlight A: Needle Insertion with Image Overlay Guidance

Researchers at the CISST ERC, in collaboration with Dr. Ken Masamune (Tokyo Denki University, Japan) and the Siemens Corporation, have developed an inexpensive 2D image overlay system to simplify, and increase the precision of, image-guided needle placements using conventional CT scanners.

Numerous studies have demonstrated the potential efficacy of image-guided needle-based therapy and biopsy in a wide variety of medical problems. However, with most systems currently in use, there is significant variability among practitioners with respect to accuracy and procedure time. Typically, the images are shown on the scanner’s console, and physician must then mentally register the images with the anatomy of the actual patient. A variety of virtual reality methods, such as head-mounted displays, video projections, and volumetric image overlay have been investigated, but all these require elaborate calibration, registration, and spatial tracking of all actors and components. This creates a rather complex and expensive engineering system.



The device developed at the CISST ERC consists of a flat LCD display and a half mirror, mounted on the gantry (see Figure 1.) When the practitioner looks at the patient through the mirror, the CT image appears to be floating inside the patient with correct size and position, thereby providing the physician with two-dimensional “X-ray vision” to guide needle placement procedures. The physician inserts the needle following the optimal path identified in the CT image and reflected in the mirror. The system increases needle placement accuracy and reduces the X-ray dose, patient discomfort, and procedure time by eliminating faulty insertion attempts. Cadaver studies have been conducted for several applications with a clinically applicable device. Dr. Laura Fayad at the Johns Hopkins Medical Institutions has also performed joint arthography of the shoulder and hip joints, achieving millimeter-level accuracy in needle placement (see Figure 2.) An IRB application for the CT-guided system and an MRI compatible prototype is under development.

Further information is available at http://www.cisst.org/people/gabor/ImageOverlay.htm



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