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Geir Arne Tangen

Publications and source records attributed to Geir Arne Tangen.

2 recordsLinked to original sources

[3-D navigation in laparoscopic surgery].

BACKGROUND: The main drawback with the laparoscopic approach is that the surgeon lacks the possibility to palpate vessels, tumours and organs during surgery. Furthermore, the laparoscope only provides a surface view of organs. There is a need for more advanced visualization that enhances the view to include information below the surface of the organs when the procedure is planned and for control and guidance during treatment. MATERIAL AND METHODS: We propose 3-D navigation technology based on preoperatively acquired MR or CT data used in combination with a laparoscopic navigation pointer. The pointer has an attached position tracker which enables the surgeon to interactively control the display of images prior to and during surgery. RESULTS: We have used this technology during treatment of four patients with adrenal tumours. Preoperative registration of images of the patients was performed within two minutes with an average accuracy of 7.1 mm. 2-D and 3-D visualizations interactively controlled by the pointer were used both for planning and for guidance of the surgical procedures. INTERPRETATION: The pointer was a useful tool in image guidance of laparoscopic surgery in the reported cases both for planning the approach in detail and for guidance. We believe abdominal 3-D image guidance using a laparoscopic navigation pointer has a large potential for improving laparoscopic surgery, especially in cases where vessels and anatomical relations might be difficult to identify using only a laparoscope. Accordingly, this new technology will increase safety and facilitate successful laparoscopic surgery.

Adrenal Gland Neoplasms↗

Probe calibration for freehand 3-D ultrasound.

Ultrasound (US) probe calibration establishes the rigid body transformation between the US image and a tracking device attached to the probe. This is an important requirement for correct 3-D reconstruction of freehand US images and, thus, for accurate surgical navigation based on US. In this study, we evaluated three methods for probe calibration, based on a single-point phantom, a wire-cross phantom requiring 2-D alignment and a wire phantom for freehand scanning. The processing of acquired data is fairly common to these methods and, to a great extent, based on automated procedures. The evaluation is based on quality measures in 2-D and 3-D reconstructed data. With each of the three methods, we calibrated a linear-array probe, a phased-array sector probe and an intraoperative probe. The freehand method performed best, with a 3-D navigation accuracy of 0.6 mm for one of the probes. This indicates that clinical accuracy in the order of 1 mm may be achieved in US-based surgical navigation.

Calibration↗