Illustrative Couinaud Segmentation for Ultrasound Liver Examinations

Couinaud segmentation is a widely used liver partitioning scheme for describing the spatial relation between diagnostically relevant anatomical and pathological features in the liver. En this paper, we propose a new methodology for effectively conveying these spatial relations during the ultrasound examinations. We visualize the two-dimensional ultrasound slice in the context of a three-dimensional Couinaud partitioning of the liver. The partitioning is described by planes in 3D reflecting the vascular tree anatomy, specified in the patient by the examiner using her natural interaction tool, i.e., the ultrasound transducer with positional tracking. A pre-defined generic liver model is adapted to the specified partitioning in order to provide a representation of the patient's liver parenchyma. The specified Couinaud partitioning and parenchyma model approximation is then used to enhance the examination by providing visual aids to convey the relationships between the placement of the ultrasound plane and the partitioned liver. The 2D ultrasound slice is augmented with Couinaud partitioning intersection information and dynamic label placement. A linked 3D view shows the ultrasound slice, cutting the liver and displayed using fast exploded view rendering. The described visual augmentation has been characterized by the clinical personnel as very supportive during the examination procedure, and also as a good basis for pre-operative case discussions.