NEW TECHNOLOGY Three-Dimensional Printing for Perioperative Planning of Complex Aortic Arch Surgery Daniel Schmauss, MD, Gerd Juchem, MD, Stefan Weber, Dr Ing, Nicolas Gerber, Dr Ing, Christian Hagl, MD, and Ralf Sodian, MD Department of Cardiac Surgery, Ludwig-Maximilians-University, Munich, Germany; and ISTB–Institute for Surgical Technology and Biomechanics, University of Bern, Bern, Switzerland Purpose. In this study, we show the use of three-dimensional printing models for pre- operative planning of surgery for patients with complex aortic arch anomalies. Description. A 70-year-old man with an extensively arteriosclerotic aneurysm reaching from the ascending aorta to the descending aorta was referred to our center for complete aortic arch replacement. We visualized and reconstructed computed tomography data of the patient and fabricated a flexible three-dimensional model of the aortic arch including the aneurysm. Evaluation. This model was very helpful for the preoperative decision making and planning of the frozen elephant trunk procedure owing to the exact and lifelike illustration of the native aortic arch. Conclusions. Three-dimensional models are helpful in preoperative planning and post- operative evaluation of frozen elephant trunk procedures in patients with complex aortic anatomy. (Ann Thorac Surg 2014;97:2160–4) Ó 2014 by The Society of Thoracic Surgeons S urgery of aortic arches with complex anatomy, eg, extensive thoracic aortic aneurysms or aortic dissec- tions, remains a challenge in cardiac surgery. The frozen elephant trunk (FET) procedure is a surgical technique developed for patients with aortic diseases involving the arch as well as the thoracic descending aorta [1, 2]. It al- lows single-stage treatment for such disease, combin- ing conventional surgery with endovascular techniques. Preoperative planning and simulation of the procedure is often difficult because of the unpredictable anatomy of the aortic arch [3]. Therefore it might be of great value to develop high-quality preoperative data for optimal sur- gical planning and simulation of an FET procedure. We developed a new rapid-prototyping technique to build three-dimensional models of the exact anatomy of the aortic arch in patients with complex aortic anatomy planned for an FET procedure. Rapid prototyping (ster- eolithography) is a technique used in engineering for building prototype models. Transferring this technology to cardiac surgery enables illustrating the exact anatomy of complex cardiovascular diseases for preoperative planning and decision making, hands-on simulation of the procedure, and intraoperative orientation. Technology and Technique We present the case of a 70-year-old man with an extensive arteriosclerotic aneurysm reaching from the ascending aorta to the descending aorta. The patient’s comorbidi- ties included arterial hypertension and diabetes mellitus. The patient was referred to our institution for complete aortic arch replacement. We performed a 64-slice com- puted tomography (CT) of the patient’s chest, visualizing the aneurysm that measured 5.5 cm in width. Owing to the complexity of the aortic anatomy and the severe calcifications of the aneurysm and the aortic arch, we decided to build a three-dimensional (3-D) model for better decision making and preoperative planning of an FET procedure (Fig 1). The patient’s CT dataset was loaded into an image processing and visualization software (Amira, Visualiza- tion Sciences Group, Burlington, MA), with which ex- traction of the aorta was completed in several steps. The user provided a seed position within the aorta to initiate a region growing with connected thresholds criteria. The lower intensity threshold was defined as 200 Hounsfield units (HU), and the upper intensity threshold was defined as 600 HU. Any pixel intensity within these thresholds was labeled as being part of the aorta. Manual segmen- tation corrections were performed to eliminate leaking voxels from the region growing. Erosion and dilation morphologic operators were subsequently applied to create the wall of the aorta with a wall thickness of 2 to 3 mm. Calcified depositions were similarly segmented Accepted for publication Feb 4, 2014. Address correspondence to Dr Sodian, Department of Cardiac Surgery, Ludwig-Maximilians-University, Marchioninistr 15, 81377 Munich, Ger- many; e-mail: ralf.sodian@med.uni-muenchen.de. Ó 2014 by The Society of Thoracic Surgeons 0003-4975/$36.00 Published by Elsevier Inc http://dx.doi.org/10.1016/j.athoracsur.2014.02.011 NEW TECHNOLOGY