Mimics 19

A 35-year-old male volunteer without any symptoms of osteoarthritis or meniscal tears was scanned by a 3 T magnetic resonance (MR) scanner (uMR 770; United Imaging Co., Ltd., Shanghai, China) and a GE Lightspeed 16-slice computed tomography (CT) scanner (GE Healthcare, Chicago, IL, USA). During the scanning, the volunteer kept the supine position with a maker on the lower limb to fit the coordination of the two scanning systems. For the MR imaging (MRI), the extended echo train sequence was performed with a slice thickness of 1.5 mm and a field of view (FOV) of 152 mm. For the CT scanning, the slice thickness was 0.625 mm, and the FOV was 500 mm.
The images saved in digital imaging and communications in medicine (DICOM) format were imported into the MIMICS 19.0 software (Materialise, Leuven, Belgium) to complete the 3D reconstruction. The bone objectives were reconstructed using the segmentation of bone structures from CT images, and the cartilage, meniscus, and ligaments were manually segmented from the MR images under the supervision of an experienced radiologist and an experienced orthopedist.

CT scan data in DICOM format were imported into a commercial software programme (Mimics 19.0 software^®, Materialise Inc., Leuven, Belgium). 3D bilateral lung image reconstructions were performed, and all images were reviewed using this software. The lungs were segmented semi-automatically with Hounsfield unit (HU) thresholds from −1 000 to 0 HU (Figure 1). In order to measure accurately, the tracheal and main bronchial areas were removed from the images. The segmented image was called the “mask”, a volume of interest including an entire lung. Based on the contiguous sections of CT imaging, lung 3D model was calculated from the mask. The image reconstruction was performed by a single operator.

Pelvic X-ray CT data of patients admitted to our hospital for reasons other than fracture between January and June of 2017 were selected. The pelvic structures of the included participants were normal. The 80 adult cases identified included 40 males and 40 females with an average age of 51.65±12.46 years and an age range of 21 to 83 years. None of the patients had anatomical abnormalities or diseases such as pelvic tumors, fracture, malformation, or severe osteoporosis. The included patients had normal pelvic structures and good bone density. The pelvic CT data were saved in digital image and communications in medicine (DICOM) format. The CT scanning parameters were as follows: a 512×512 matrix, 100-140 kV voltage, 360 mA current, 1-mm interslice interval, and 1-1.5 mm slice thickness (SOMATOM Definition Flash, SIEMENS Ltd., USA). The 3D reconstructions using the CT data, screw insertion simulation, and parameter measurements were performed using Mimics 19.0 software (Materialise, Belgium). The hospital ethics committee approved this study under ethical clearance number 2018-102.

The design process of a 3D printed prosthesis is displayed in Figure 1. First, the computed tomography (CT) scan data of bilateral limbs were acquired and reconstructed using Mimics 19.0 software (Materialise, Belgium). Second, the healthy bone was mirrored to the disease-affected side, and the defect regions overlapped one another (automatically and manually). Third, the bone defect model obtained from Mimics was imported into Geomagic Studio 12 software (Geomagic, United States) for modification, after which personal prostheses with various shapes were designed according to specific defects and doctor’s requests. Fourth, the prosthesis insertion and fixation procedures were simulated via medical interaction platform; size, matching degree, and screw position was further evaluated. Any design that could not meet the surgical requirements was redesigned or modified and locally optimized.