Concept and objectives

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Eligibility for liver surgery is based on various criteria and rules defined for partial liver resection and transplants. Liver transplants in Europe represents 5, 000 procedures per year (source European Liver Transplant Registry), however, remains limited by the number of possible donors and specific rules such as the Milan criteria limiting transplants to patients with a single nodule of less than 5 cm or up to three nodules with none larger than 3 cm. Fortunately, organ transplant is not the only solution. Indeed, the liver is able to regenerate its substance. This means that when part of the liver is removed, the volume of the remaining liver increases until it approaches the volume of the original entire liver. Bile ducts and blood vessels do not grow back, it is thus essential to preserve these vascular networks as much as possible. The 2006 San Francisco consensus conference established that two adjacent liver segments can be separated with an adequate vascular inflow and outflow as well as biliary drainage and that the standardized Future Liver Remnant (Standardized FLR = remnant liver volume/liver volume) must be over 20% for patients with an otherwise normal liver, 30% for patients who have received extensive preoperative systemic chemotherapy, and 40% for patients with existing chronic liver diseases such as hepatitis, fibrosis or cirrhosis. This recent consensus clearly shows that the eligibility for resection is not only based on geometrical information (such as the total volume of the liver) or topological information (such as vascular networks) that can be extracted from 3D medical imaging (CT-scan or MRI), but also on clinical signs obtained by physical aspects and patient examinations as well as symptoms, for instance, pain, functional problems, discomfort, etc. and finally on functional and physiological information that are essentially provided by blood analysis and/or biopsies. All this information is used by practitioners who decide, from their own knowledge, the best therapy to apply to their patients. Although today, this knowledge is improved by new technology, unfortunately there is no system that allows the management of these various data linking patient health information to the practitioner’s knowledge in which to apply the best therapy. Moreover, no system today provides a patient specific minimal safety standardized FLR, which in the end result is the most important criteria when deciding upon surgical eligibility. The final decision is thus, totally dependent on the practitioner’s personal experience and feeling.

The liver is one of the major organs in the human body and is in charge of more than 100 vital functions. Because of its many functions, its pathologies are also varied, numerous and unfortunately often lethal. This is the case of Hepatitis viruses for instance, which today affects more than 8,5 million European citizens for Hepatitis B (HBV) and over 5 million people for the Hepatitis C (HCV) (source European Liver Patient Association). The most advanced state of evolution of these pathologies is generally cirrhosis and cancer. In 2006, over 45.000 European citizens died of cirrhosis of the liver and 44,000 additional citizens of liver cancer, knowing that the same year 48,700 new liver cancer cases were declared and that the 5-year survival rate of liver cancer is 10% (source International Agency for Research on Cancer). Surgical procedures remain the option that offers the foremost success rates against such pathologies for patients that survive in the long run. Indeed, the 5-year survival rate is currently estimated at less than 20% considering chemotherapy alone, up to 20% for thermal ablation and between 50% and 90% for surgery. Regretfully, such interventions cannot be performed for all patients as the eligibility rules for liver surgery lack accuracy and may include many exceptions. To illustrate these drawbacks, unfortunately only 7,271 surgical interventions were carried out on the liver in France in 2005, (942 were liver transplants), compared to the 20,497 cirrhosis cases and 14,267 new liver cancer cases that were documented that same year (source PMSI).

The PASSPORT for Liver Surgery project fully addresses the expectations of the ICT work programmes and in particular, Challenge 5, “towards sustainable and personalised healthcare”. More specifically, this 3-year project deals directly with the objectives of the “Virtual Physiological Human” ICT-2007.5.3 objective. Indeed, PASSPORT’s aim is to develop patient-specific models of the liver which integrates anatomical, functional, mechanical, appearance, and biological modelling. To these static models, PASSPORT will add dynamics liver deformation modelling and deformation due to breathing, and regeneration modelling providing a patient specific minimal safety standardized FLR. These models, integrated in the Open Source framework SOFA, will culminate in generating the first multi-level and dynamic “Virtual patient-specific liver” allowing not only to accurately predict feasibility, results and the success rate of a surgical intervention, but also to improve surgeons’ training via a fully realistic simulator, thus directly impacting upon definitive patient recovery suffering from liver diseases.