Towards Video Guidance for Ultrasound, Using a Prior High-Resolution 3D Surface Map of the External Anatomy

We are developing techniques for guiding ultrasound probes and other clinical tools with respect to the exterior of the patient, using one or more video camera(s) mounted directly on the probe or tool. This paper reports on a new method of matching the real-time video image of the patient's exterior against a prior high-resolution surface map acquired with a multiple-camera imaging device used in reconstructive surgery. This surface map is rendered from multiple viewpoints in real-time to find the viewpoint that best matches the probe-mounted camera image, thus establishing the camera's pose relative to the anatomy. For ultrasound, this will permit the compilation of 3D ultrasound data as the probe is moved, as well as the comparison of a real-time ultrasound scan with previous scans from the same anatomical location, all without using external tracking devices. In a broader sense, tools that know where they are by looking at the patient's exterior could have an important beneficial impact on clinical medicine.