摘要：

This paper investigates the possibility of using the motion of a patient's anterior surface in combination with a motion model to compensate for internal respiratory motion during tracked biopsies. Position data from two electromagnetically tracked sensors, one placed on the patient's sternum, the other incorporated into a biopsy needle, were acquired during a liver biopsy. The data were used to evaluate the correlation between the position measurements of the two sensors and to derive an affine motion model to assess respiratory motion compensation for image-guided interventional procedures. The correlation reached up to 94% for ranges of steady respiration. The residual motion of the internal sensor after compensation is reduced by a factor of approximately four.Keywords: Respiratory motion compensation, interventional navigation, electromagnetic tracking, IntroductionComputer aided surgery and interventional procedures using magnetic tracking systems for image-guidance have recently shown promising results Wood BJ, Zhang H, Durrani A, Glossop N, Ranjan S, Lindisch D, Levy E, Banovac F, Borgert J, Krüger S, Krücker J, Viswanathan A, Cleary K. Navigation with electromagnetic tracking for interventional radiology procedures: A feasibility study. J Vasc Interv Radiol 2005; 16: 493–505 Solomon SB, Dickfield T, Calkins H. Real-time cardiac catheter navigation on three-dimensional CT, images. J Interventional Cardiac Electrophysiol 2003; 8: 27–36 Solomon SB, White P, Wiener CM, Orens JB, Wang KP. Three-dimensional CT-guided bronchoscopy with a real-time electromagnetic position sensor. Chest 2000; 118: 1783–1787 Solomon SB, Magee CA, Acker DE, Venbrux AC. Experimental nonfluoroscopic placement of inferior vena cava filters: Use of an electromagnetic navigation system with previous CT data. J Vasc Interv Radiol 1999; 10: 92–95 Ben-Haim SA, Osadchy D, Schuster I, Gepstein L, Hayam G, Josephson ME. Nonfluoroscopic, in vivo navigation and mapping technology. Nature Medicine 1996; 2(12)1393–1395. The magnetic tracking system (MTS) is used to determine the position and orientation of interventional devices such as biopsy or radiofrequency ablation (RFA) needles. The devices are registered to pre-procedurally acquired anatomical images, usually from computed tomography (CT) or magnetic resonance imaging (MRI), to enable image guidance during the application.Biopsies and ablations have become standard techniques for the diagnosis and treatment of certain oncology applications, including lung, kidney, and liver tumors Wood BJ, Ramkaransingh JR, Fojo T, Walther MM, Libutti SK. Percutaneous tumor ablation with radiofrequency. Cancer 2002; 94(2)443–451. These procedures are usually performed under ultrasound, CT, CT-fluoroscopy, or even MRI guidance. Procedures that target lesions located in the liver are generally performed percutaneously or with laparoscopic support Krücker J, Viswanathan A, Borgert J, Glossop N, Yang Y, Wood BJ (2005) An electro-magnetically tracked laparoscopic ultrasound for multi-modality minimally invasive surgery. Computer Assisted Radiology and Surgery. Proceedings of the 19th International Congress and Exhibition (CARS 2005), BerlinGermany, June, 2005, HU Lemke, K Inamura, K Doi, MW Vannier, AG Farman. Elsevier, Amsterdam, 746–751, reducing the surgical exposure required Leyendecker JR, Dodd GD III. Minimally invasive techniques for the treatment of liver tumors. Seminars in Liver Disease 2001; 21(2)283–291. In contrast to well-established optical position measurement systems, magnetic tracking systems do not suffer from line-of-sight restrictions and are therefore especially suited for use in percutaneous procedures, since the tracked element can be placed at the tip of a flexible instrument. The potential advantages of these less invasive procedures include the ability to be used in an outpatient setting, less blood loss, faster recovery, shorter hospital stays, reduced use of pain medication, and reduced costs. In addition, some interventional or minimally invasive procedures can be performed on patients wh

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