Application of a Three-Dimensional Print of a Liver in Hepatectomy for Small Tumors Invisible by Intraoperative Ultrasonography: Preliminary Experience

In this era of increasing healthcare technification, surgical outcomes are constantly under scrutiny, and surgical teams should bring the proof of using the most up-to-date technology to offer the best of care to patients in terms of safety and efficacy. Intraoperative real-time imaging, particularly in surgical oncology, should constantly guide surgical resections in order to maximize the chances of complete tumor removal and reduce the risks of collateral damage. Intraoperative ultrasonography (IOUS), in expert hands, is an ideal tool for surgical navigation during liver oncologic resections. However, some lesions can ‘‘disappear’’ after neo-adjuvant protocols and remain undetected at IOUS. Tsuyoshi et al. proposed an ingenious solution to help the surgeon deal with disappearing metastasis from colorectal cancer: print a smaller-sized, patient-specific, semi-transparent 3D model of the patient’s liver, including lesions. With the physical model in hands, the surgeon’s brain is helped in spatial reconstruction and could more safely define resection lines. However, the 3D printed model navigation presents a major limitation, the problem of the ‘‘model’s rigidity,’’ which is shared by an alternative navigation method, augmented reality (AR), a domain in which we have been working for more than 10 years. The printed liver is rigid and represents a ‘‘snapshot’’ of the anatomical ‘‘in situ’’ situation, which is different from the intraoperative status, after a laparotomy has been performed and when the liver has been mobilized by the surgeon’s hands. Virtual Reality medical software (such as PLUTO used by the authors) may elaborate a 3D virtual model of the patient from preoperative CT-scans or magnetic resonance imaging studies. The 3D virtual model allows to navigate through the patient’s anatomy and perform a virtual exploration, which can detect anatomical details more precisely than standard images [1, 2]. The strong point of the virtual model is in that anatomical structures can be separately displayed or hidden, allowing, for example, better understanding of the relationships between portal and biliary system in the liver. Additionally, it allows for accurate automatic measure of liver volumetry [3]. The virtual model can also be used to plan and simulate the strategy for a targeted therapy, surgical or ablative. After planning, the 3D virtual model may be superimposed intraoperatively, with real-time patient images giving AR, helping to visualize unapparent structures, such as vessels and tumors using modular virtual organ transparency. AR navigation is very accurate in brain surgery [4] and maxillofacial surgery [5], in which the preoperatively generated virtual model remains congruent because of motionless and highly contrasted structures such as bones. In digestive surgery or interventional radiology, AR presents several challenges due to respiratory motion and to deformation of soft tissues during surgical manipulation, which makes the process of registration difficult (i.e., perfect overlaying of synthetic and real images). The first clinical application of AR for visceral surgery was performed by our group at the IRCAD in laparoscopic adrenalectomy [6], using a specific software (VRJ. Marescaux (&) M. Diana L. Soler IHU-Strasbourg, Image-Guided Surgery University Institute, Strasbourg, France e-mail: jacques.marescaux@ircad.fr