Patient-Specific Anatomy: The New Area of Anatomy Based on 3D Modelling

Abstract

3D anatomical medical imaging (CT-scan or MRI) can provide a vision of patient anatomy and pathology. But for any human, even experts, these images have two drawbacks: each voxel density is visualized in grey levels, which are totally inadequate for human eye cones’ perception, and the volume is cut in slices, making any 3D mental representation of the real 3D anatomy of the patient highly complex. Usually, the limits of human perception are overcome by human knowledge. In anatomy, this knowledge is a mix between the average anatomy definition and anatomical variations. But how to understand an anatomical variation from slices in grey levels? In routine, such a difficulty can sometimes be so important that it creates errors. Fortunately, these mistakes can be overcome through 3D patient-specific surgical anatomy. New computer-based medical image analysis and associated 3D modelling provide a highly efficient solution by allowing a patient-specific virtual copy of their anatomic reconstruction. Some articles reporting clinical studies show that up to one-third of initial planning is modified using 3D modelling, and that this modification is always validated efficiently intraoperatively. They also demonstrate that major errors can thus be avoided. In this chapter, we propose to illustrate the 3D modelling process and the associated benefit on a set of patient clinical cases in three main domains: liver surgery, thoracic surgery, and kidney surgery. In each case, we will present the limits of usual medical image analysis due to an average anatomical definition and limited human perception. 3D modelling is provided by the Visible Patient online service and the surgeon then plans his/her surgery on a simple PC using the Visible Patient Planning software. We will then compare the result obtained from a normal anatomical analysis with the result obtained from the 3D modelling and associated preoperative planning. These examples illustrate the great benefit of using patient-specific 3D modelling and preoperative virtual planning in comparison with the usual anatomical definition using only medical image slices. These examples also confirm that this new patient-specific anatomy corrects many mistakes created by the current standard definition, increased by physician interpretation that can vary from one person to another.