This publication was supported by the Beijing Municipal Natural Science Foundation (L192059).

All data come from the clinical patient, whose SDR operation was carried out at BJ Dongzhimen Hospital. The protocol follows the guidelines of and was approved by the Dongzhimen Hospital research ethics committee.
NOTE: The whole map of the model reconstruction protocol is shown in Figure 1. The high-resolution computed tomography (HRCT) data and Dixon data are raw materials for modeling; then, the 3D model creation consists of image registration and fusion. The final 3D digital model is printed by PolyJet technology which is a high-precision 3D printing process that produces smooth and accurate parts using a wide range of materials. In order to describe the spatial relationship between the vertebra and spinal nerve exactly, HRCT data and Dixon image series are used. The Dixon scanning can identify water and fat separation images, in which the Dixon water phase image series can be used to extract the structure of the spinal nerves, and the Dixon-in phase image series can be used to check the registration of the bone structure.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/65093/65093fig01.jpg" /> 
Figure 1: The whole map of the protocol. The research methodology of this study involves the fusion of CT and magnetic resonance Dixon sequences. Specifically, the CT vertebrae structure is registered with the identical vertebrae structure contained in the Dixon-in sequence, followed by fusion with the Dixon-w sequence for the spinal nerve. <a href="https://jove.unicartagenaproxy.elogim.com/files/ftp_upload/65093/65093fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
1. Data collection and preparation
<ol>
	<li>High-resolution CT for vertebrae 
	NOTE: The parameter difference is not sensitive to the research method.
	<ol>
		<li>Set the data resources from the CT machine station. 
		NOTE: Here, the SIEMENS-CTAWP73396 CT machine is used.</li>
		<li>Open the Syngo CT 2012B software to receive data from the scanning protocol SpineRoutine_1. Select the Pixel Size and Slice Thickness (ST) of the dataset to adapt to the size of the vertebrae intended to be represented in the 3D digital model.</li>
		<li>Use an ST of 1 mm with a matrix size of 512 pixels x 512 pixels, in which the pixel spacing is 0.3320 mm. The actual size of the 3D volume achieved is 512 x 512 x 204 voxels.</li>
	</ol>
	</li>
	<li>Dixon sequence for spinal nerve 
	&#8203;NOTE: A 1.5 T MRI machine is used in this study.
	<ol>
		<li>Set the Dixon image Resolution as 290 pixels x 320 pixels, Pixel Spacing as 0.9375 mm, and Slice Thickness as 3 mm to obtain accurate data.</li>
		<li>Set the Repetition Time as 5,160 ms and the Echo Time as 94 ms.</li>
		<li>Ensure every scanned layer consists of four-phase images, which are Dixon-in, Dixon-opp, Dixon-F, and Dixon-w.</li>
	</ol>
	</li>
	<li>Prepare data-storing files for model reconstruction. 
	NOTE: A well-defined data-storing structure is more convenient for follow-up work.
	<ol>
		<li>Make a project folder to contain all the data belonging to the patient.</li>
		<li>Prepare different file paths for HRCT and MRI-Dixon data by making different folders for the digital imaging and communications in medicine (DICOM) data.</li>
		<li>Make a separate folder under the project for all analysis results.</li>
	</ol>
	</li>
</ol>
2. The 3D digital vertebrae model
NOTE: All subprocess functions come from software tools, whose property belongs to Beijing Intelligent Entropy Science &#38; Technology Co Ltd.
<ol>
	<li>Call the Dicom2Mat subprocess in the MATLAB workplace to obtain the 3D volume from the DICOM files stored in the HRCT data folder.</li>
	<li>After undergoing the Dicom2Mat subprocess, view each slice within the 3D volume through the graphical user interface (GUI), as depicted in Figure 2.</li>
	<li>Then, visualize the intensity distribution of the vertebrae HRCT data by the hist function (Figure 3).</li>
	<li>Call the NoiseClean subprocess to delete signal noise formed by the device under the HRCT data file paths.</li>
	<li>Use the Vertebrae function subprocess under the same path to gain the vertebrae model, which is also a 3D volume but only with the bone structure (Figure 4). The high-pass filter parameters, the intensity ranging from 190 to 1,656.</li>
</ol>
3. The 3D digital spinal nerve model
NOTE: Dixon-in contains bone structure, while Dixon-w describes neural structure.
<ol>
	<li>Use the Dicom2Mat subprocess in both paths of the Dixon-in and Dixon-w sequences and get their 3D volume.</li>
	<li>Furthermore, visualize each individual slice that constitutes a 3D volume using the GUI presented in Figure 5. Access this visualization once the Dicom2Mat subprocess has been completed.</li>
	<li>Use the Spinal_Nerve function to reconstruct the spinal nerve model with high-pass filter parameters, the intensity ranging from 180 to 643. Because the signals of the nerve in the Dixon-w sequence are very high, extract the spinal nerve 3D volume by filtering out points with low intensity.</li>
	<li>When the Spinal_Nerve subprocess is finished, check the model generated in the GUI shown in Figure 6.</li>
</ol>
4. Registration and fusion
NOTE: The key insight is that bone architecture is present in both HRCT and Dixon-in imaging sequence.
<ol>
	<li>Copy the three 3D volumes obtained so far to the file path of the project made in step 3.1. The models from HRCT and Dixon-in include the same vertebrae structure, and the models from Dixon-in and Dixon-w have the same coordinates.</li>
	<li>Then, put the three models&#39; filenames into the vertebra_fusion subprocess as an input to generate the fusion model. This can be visualized in Figure 7.</li>
	<li>The fusion is usually well done. If fine-tuning is necessary from the doctor&#39;s perspective, add coordinate parameters in all directions to the same function to correct the fusion model. If slight errors are observed in fusion from a clinical perspective, use the vertebra_fusion function to fine-tune the fusion coordinates. This process involves parameter adjustments to the six dimensions of coordinate direction (XYZ coordinates and their rotation).</li>
	<li>Make a separate folder in the project directory for outputting the result of the fusion model.</li>
</ol>
5. Digital model files for 3D printing
NOTE: A fully-developed 3D printing apparatus is utilized for the manufacturing of the aforementioned digital model, with the implementation of Delaunay triangulations. Here, the Stratasys J55 Prime 3D printer was used.
<ol>
	<li>Export the fusion models to be used for 3D printing in the DICOM format sequences under the file path of the fusion directory. Utilize the Mat2Dicom algorithm to execute the export operation by inputting the fusion model.</li>
	<li>Open the DICOM file sequence exported previously using Materialise Mimics V20. To perform the export operation, navigate to the Export menu under the File tab and select the VRML format. The file path for the export can be freely customized according to the user&#39;s requirements.</li>
	<li>As transparent colorful 3D printing is a professional service, compress and pack the VRML files and send them to the service provider. The 3D printing result is shown in Figure 8.</li>
</ol>

<ol>
	<li>Rosenbaum, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+report:+the+definition+and+classification+of+cerebral+palsy+April+2006.">A report: the definition and classification of cerebral palsy April 2006.</a> Developmental Medicine and Child Neurology. Supplement. 109, 8-14 (2007).</li><li>Krigger, K. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+palsy:+an+overview.">Cerebral palsy: an overview.</a> American Family Physician. 73 (1), 91-100 (2006).</li><li>Davidson, B., Fehlings, D., Milo-Manson, G., Ibrahim, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improving+access+to+selective+dorsal+rhizotomy+for+children+with+cerebral+palsy.">Improving access to selective dorsal rhizotomy for children with cerebral palsy.</a> Canadian Medical Association Journal. 191 (44), E1205-E1206 (2019).</li><li>Buizer, A. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+dorsal+rhizotomy+in+children+with+cerebral+palsy.">Selective dorsal rhizotomy in children with cerebral palsy.</a> The Lancet. Child &amp; Adolescent Health. 3 (7), 438-439 (2019).</li><li>Wong, K. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=3D-printed+patient-specific+applications+in+orthopedics.">3D-printed patient-specific applications in orthopedics.</a> Orthopedic Research and Reviews. 8, 57-66 (2016).</li><li>Wong, K. C., Kumta, S. M., Geel, N. V., Demol, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=One-step+reconstruction+with+a+3D-printed,+biomechanically+evaluated+custom+implant+after+complex+pelvic+tumor+resection.">One-step reconstruction with a 3D-printed, biomechanically evaluated custom implant after complex pelvic tumor resection.</a> Computer Aided Surgery. 20 (1), 14-23 (2015).</li><li>Zhu, R., Li, X., Zhang, X., Ma, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=MRI+and+CT+medical+image+fusion+based+on+synchronized-anisotropic+diffusion+model.">MRI and CT medical image fusion based on synchronized-anisotropic diffusion model.</a> IEEE Access. 8, 91336-91350 (2020).</li><li>Park, T. S., Gaffney, P. E., Kaufman, B. A., Molleston, M. 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A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Selective+posterior+rhizotomy:+evolution+of+theory+and+practice.">Selective posterior rhizotomy: evolution of theory and practice.</a> Pediatric Neurosurgery. 17 (3), 128-134 (1991).</li><li>Vitrikas, K., Dalton, H., Breish, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cerebral+palsy:+an+overview.">Cerebral palsy: an overview.</a> American Family Physician. 101 (4), 213-220 (2020).</li><li>Niikura, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Tactile+surgical+navigation+system+for+complex+acetabular+fracture+surgery.">Tactile surgical navigation system for complex acetabular fracture surgery.</a> Orthopedics. 37 (4), 237-242 (2014).</li><li>Lepisto, J., Armand, M., Armiger, R. 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The digital models in this study are reconstructed by co-author Fangliang Xing.

This study provides a workflow for establishing a preoperative 3D printing model of the lumbar spine in patients with cerebral palsy, with the aim of facilitating preoperative planning for SDR surgery and enhancing anatomical training based on the patient's specific model. The study aims to establish a highly reliable 3D-printed model that accurately demonstrates the patient's lumbar vertebral and nerve structures. By measuring the position of the lamina and spinal nerve in the model before surgery, precise planning of t...

Spastic cerebral palsy affects over half of all children with cerebral palsy1, leading to tendon contractures, abnormal skeletal development, and decreased mobility, greatly impacting the quality of life of affected children2. As the main surgical method for the treatment of spastic cerebral palsy, selective dorsal rhizotomy (SDR) has been fully validated and recommended by many countries3,4. However, the intricate and high-risk nature of SDR surgery, including the precise cutting of the lamina, positioning and dissociation of nerve roots, and severing of nerve fibers, presents a significant challenge for young doctors who are just beginning to engage with SDR in clinical practice; further, the learning curve of SDR is very steep.
In traditional orthopedic surgery, surgeons must mentally integrate all preoperative two-dimensional (2D) images and create a 3D surgical plan5. This approach is particularly difficult for preoperative planning involving complex anatomical structures and surgical manipulations, such as SDR. With advances in medical imaging and computer technology, 2D axial images, such as computed tomography (CT) and magnetic resonance imaging (MRI) can be processed to create 3D virtual models with patient-specific anatomy6. With improved visualization, surgeons can analyze this processed information to make more detailed diagnoses, planning, and surgical interventions tailored to the patient&#39;s condition. In recent years, the application of multimodal image fusion technology in orthopedics has gradually attracted attention7. This technology could fuse CT and MRI images, greatly improving the accuracy of the digital3D analog model. However, the application of this technique in preoperative models of SDR has not been researched yet.
Accurate positioning of the lamina and spinal nerve and precise cutting during SDR surgery are crucial for successful outcomes. Typically, these tasks rely on experts&#39; experience and are confirmed repeatedly by a C-arm during the operation, resulting in a complex and time-consuming surgical process. The 3D digital model serves as the foundation for future SDR surgical navigation and can also be utilized for preoperative planning of laminectomy procedures.&#160;This model fuses the bone structure from CT and the spinal nerve structure from MRI, and assigns different colors to the lumbar vertebra sections marked for cutting according to the surgical plan. Such holographic 3D printing models for SDR not only facilitate preoperative planning and simulation, but also output accurate 3D navigation coordinates to the intraoperative robotic arm for precise cutting.

<table><tbody><tr><td>J55 Prime 3D-Printer</td><td>Stratasys</td><td>J55 Prime</td><td>Manufacturing the model</td></tr><tr><td>MATLAB</td><td>MathWorks&amp;nbsp;</td><td>2022B</td><td>Computing and visualization&amp;nbsp;</td></tr><tr><td>Mimics</td><td>Materialise</td><td>Mimics Research V20</td><td>Model format transformation</td></tr><tr><td>Tools for volum fusion</td><td>Intelligent Entropy</td><td>VolumeFusion V1.0</td><td>Beijing Intelligent Entropy Science &amp;amp; Technology Co Ltd.&lt;br/&gt; Modeling for CT/MRI fusion</td></tr></tbody></table>

3d printing model of a patient's specific lumbar vertebra

Selective dorsal rhizotomy (SDR) is a difficult, risky, and sophisticated operation, in which a laminectomy should not only expose an adequate surgical field of view but also protect the patient&#39;s spinal nerves from injury. Digital models play an important role in the pre-and intra-operation of SDR, because they can not only make doctors more familiar with the anatomical structure of the surgical site, but also provide precise surgical navigation coordinates for the manipulator. This study aims to create a 3D digital model of a patient-specific lumbar vertebra that can be used for planning, surgical navigation, and training of the SDR operation. The 3D printing model is also manufactured for more effective work during these processes.
Traditional orthopedic digital models rely almost entirely on computed tomography (CT) data, which is less sensitive to soft tissues. Fusion of the bone structure from CT and the neural structure from magnetic resonance imaging (MRI) is the key element for the model reconstruction in this study. The patient&#39;s specific 3D digital model is reconstructed for the real appearance of the surgical area and shows the accurate measurement of inter-structural distances and regional segmentation, which can effectively help in the preoperative planning and training of SDR. The transparent bone structure material of the 3D-printed model allows surgeons to clearly distinguish the relative relationship between the spinal nerve and the vertebral plate of the operated segment, enhancing their anatomical understanding and spatial sense of the structure. The advantages of the individualized 3D digital model and its accurate relationship between spinal nerve and bone structures make this method a good choice for preoperative planning of SDR surgery.

Based on lumbar CT/MRI image fusion data in children with cerebal palsy, we created a representative model of the lumbar spine combined with spinal nerves. High-pass filtering was used to extract the high signal in the CT value range of 190-1,656 from HRCT, so as to achieve the reconstruction of the bone structure of the lumbar spine in the operation area. Spinal nerve structures were reconstructed by the high-pass filtering of Dixon-w sequences in MRI. The digital model and point cloud data coordinates of the lumbar ver...

Watch this Scientific Journal Video about 3D Printing Model of a Patient's Specific Lumbar Vertebra at JoVE.com

3D Printing Model of a Patient's Specific Lumbar Vertebra

This study aims to create a 3D-printed model of a patient-specific lumbar vertebra, which contains both the vertebra and spinal nerve models fused from high-resolution computed tomography (HRCT) and MRI-Dixon data.

Selective dorsal rhizotomy (SDR) is a difficult, risky, and sophisticated operation, in which a laminectomy should not only expose an adequate surgical ...

3d-printing-model-of-a-patient-s-specific-lumbar-vertebra

Universidad de Cartagena UDEC

Research

JoVE Journal

Medicine

1.7K Views.  Beijing University of Chinese Medicine. This study aims to create a 3D-printed model of a patient-specific lumbar vertebra, which contains both the vertebra and spinal nerve models fused from high-resolution computed tomography (HRCT) and MRI-Dixon data.

Video: 3D Printing Model of a Patient's Specific Lumbar Vertebra

Evaluating Regional Pulmonary Deposition using Patient-Specific 3D Printed Lung Models

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict regional aerosol delivery. Leveraging 3D printing to generate patient-specific lung models, we outline the design of a high-throughput, in vitro experimental setup for quantifying lobular pulmonary deposition. This system is made with a combination of commercially available and 3D printed components and allows the flow rate through each lobe of the lung to be independently controlled. Delivery of fluorescent aerosols to each lobe is measured using fluorescence microscopy. This protocol has the potential to promote the growth of personalized medicine for respiratory diseases through its ability to model a wide range of patient demographics and disease states. Both the geometry of the 3D printed lung model and the air flow profile setting can be easily modulated to reflect clinical data for patients with varying age, race, and gender. Clinically relevant drug delivery devices, such as the endotracheal tube shown here, can be incorporated into the testing setup to more accurately predict a device&#8217;s capacity to target therapeutic delivery to a diseased region of the lung. The versatility of this experimental setup allows it to be customized to reflect a multitude of inhalation conditions, enhancing the rigor of preclinical therapeutic testing.

We present a high-throughput, in vitro method for quantifying regional pulmonary deposition at the lobe level using CT scan-derived, 3D printed lung models with tunable air flow profiles.

Development of targeted therapies for pulmonary diseases is limited by the availability of preclinical testing methods with the ability to predict ...

Bioengineering

Voxel Printing Anatomy: Design and Fabrication of Realistic, Presurgical Planning Models through Bitmap Printing

Most applications of 3-dimensional (3D) printing for presurgical planning have been limited to bony structures and simple morphological descriptions of complex organs due to the fundamental limitations in accuracy, quality, and efficiency of the current modeling paradigm. This has largely ignored the soft tissue critical to most surgical specialties where the interior of an object matters and anatomical boundaries transition gradually. Therefore, the needs of the biomedical industry to replicate human tissue, which displays multiple scales of organization and varying material distributions, necessitate new forms of representation. 
Presented here is a novel technique to create 3D models directly from medical images, which are superior in spatial and contrast resolution to current 3D modeling methods and contain previously unachievable spatial fidelity and soft tissue differentiation. Also presented are empirical measurements of novel, additively manufactured composites that span the gamut of material stiffnesses seen in soft biological tissues from MRI and CT. These unique volumetric design and printing methods allow for deterministic and continuous adjustment of material stiffness and color. This capability enables an entirely new application of additive manufacturing to presurgical planning: mechanical realism. As a natural complement to existing models that provide appearance matching, these new models also allow medical professionals to "feel" the spatially varying material properties of a tissue simulant-a critical addition to a field in which tactile sensation plays a key role.

This method demonstrates a voxel-based 3D printing workflow, which prints directly from medical images with exact spatial fidelity and spatial/contrast resolution. This enables the precise, graduated control of material distributions through morphologically complex, graduated materials correlated to radiodensity without loss or alteration of data.

Most applications of 3-dimensional (3D) printing for presurgical planning have been limited to bony structures and simple morphological descriptions of ...

Three-Dimensional Printing of a Complex Aortic Anomaly

Complex congenital aortic anomalies include diverse types of malformations that may be clinically asymptomatic or present with respiratory or esophageal symptoms. These anomalies may be associated with other congenital heart diseases. It is hard to identify the accurate anatomic vessel location from two-dimensional imaging data, such as computed tomography. As an additive manufacturing method, three-dimensional (3-D) printing can covert the acquired imaging data into 3-D physical models. This protocol describes the procedure for modeling the volumetric DICOM imaging into 3-D data and printing it as an anatomically realistic 3-D model. Using this model, surgeons can identify the vessel location of complex aortic anomalies, which is helpful for pre-operative planning and intra-operative guidance.

Here, we present a protocol to use three dimensional printed models for pre-operative planning and intra-operative reorganization of complicated vascular locations when handling a congenital aortic anomaly.

Complex congenital aortic anomalies include diverse types of malformations that may be clinically asymptomatic or present with respiratory or esophageal ...

Precision Measurements and Parametric Models of Vertebral Endplates

Detailed and comprehensive geometric data of vertebrae endplates is important and necessary to improve the fidelity of finite element models of the spine, design and ameliorate spinal implants, and understand degenerative changes and biomechanics. In this protocol, a high-speed and highly accurate scanner is employed to convert morphology data of endplate surfaces into a digital point cloud. In the software system, the point cloud is further processed and reconstructed into three dimensions. Then, a measurement protocol is performed, involving a 3D coordinate system defined to make each point a 3D coordinate, three sagittal and three frontal surface curves that are symmetrically fitted on the endplate surface, and 11 equidistant points that are selected in each curve. Measurement and spatial analyses are finally performed to obtain geometric data of the endplates. Parametric equations representing the morphology of curves and surfaces are fitted based on the characteristic points. The suggested protocol, which is modular, provides an accurate and reproducible method to obtain geometric data of vertebral endplates and may assist in more sophisticated morphological studies in the future. It will also contribute to designing personalized spinal implants, planning surgical acts, making clinical diagnoses, and developing accurate finite element models.

A reverse engineering system is employed to record and obtain detailed and comprehensive geometry data of vertebral endplates. Parametric models of vertebral endplate are then developed, which are beneficial to designing personalized spinal implants, making clinical diagnoses, and developing accurate finite element models.

Detailed and comprehensive geometric data of vertebrae endplates is important and necessary to improve the fidelity of finite element models of the spine, ...

Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty (PVP)

Percutaneous vertebroplasty (PVP) is considered an effective treatment for the back pain caused by osteoporotic vertebral compression fracture. The accuracy of PVP mainly depends on the surgeons&#39; experience and multiple fluoroscopes during a traditional procedure. Puncture related complications were reported all over the world. To make the surgical procedure more precise and decrease the rate of puncture-related complications, our team applied a three-dimensional printing guide template to PVP to modify the traditional procedure. This protocol introduces how to model target vertebrae DICOM imaging data into three-dimensions in the software, how to simulate operation in this 3-D model, and how to use all of the surgical data to reconstruct a patient specific template for application. Using this template, surgeons can identify suitable puncture points accurately to improve the accuracy of the operation. The whole protocol includes: 1) diagnosis of the osteoporotic vertebral compression fracture; 2) acquisition of CT imaging of the target vertebra; 3) simulation of the operation in the software; 4) design and fabrication of the 3-D printing guide template; and 5) application of the template into an operation procedure.

Three-Dimensional Printing Guide Template Assisted Percutaneous Vertebroplasty PVP

Herein, we present a three-dimensional printing guide template for percutaneous vertebraplasty. A patient with a T11 vertebral compression fracture was selected as a case study.

Percutaneous vertebroplasty (PVP) is considered an effective treatment for the back pain caused by osteoporotic vertebral compression fracture. The ...

Multicolor 3D Printing of Complex Intracranial Tumors in Neurosurgery

Three-dimensional (3D) printing technologies offer the possibility of visualizing patient-specific pathologies in a physical model of correct dimensions. The model can be used for planning and simulating critical steps of a surgical approach. Therefore, it is important that anatomical structures such as blood vessels inside a tumor can be printed to be colored not only on their surface, but throughout their whole volume. During simulation this allows for the removal of certain parts (e.g., with a high-speed drill) and revealing internally located structures of a different color. Thus, diagnostic information from various imaging modalities (e.g., CT, MRI) can be combined in a single compact and tangible object.
However, preparation and printing of such a fully colored anatomical model remains a difficult task. Therefore, a step-by-step guide is provided, demonstrating the fusion of different cross-sectional imaging data sets, segmentation of anatomical structures, and creation of a virtual model. In a second step the virtual model is printed with volumetrically colored anatomical structures using a plaster-based color 3D binder jetting technique. This method allows highly accurate reproduction of patient-specific anatomy as shown in a series of 3D-printed petrous apex chondrosarcomas. Furthermore, the models created can be cut and drilled, revealing internal structures that allow for simulation of surgical procedures.

The protocol describes the fabrication of fully colored three-dimensional prints of patient-specific, anatomical skull models to be used for surgical simulation. The crucial steps of combining different imaging modalities, image segmentation, three-dimensional model extraction, and production of the prints are explained.

Three-dimensional (3D) printing technologies offer the possibility of visualizing patient-specific pathologies in a physical model of correct dimensions. ...

3D Planning and Printing of Patient Specific Implants for Reconstruction of Bony Defects

We are in the midst of the 3D era in most aspects of life, and especially in medicine. The surgical discipline is one of the major players in the medical field using the constantly developing 3D planning and printing capabilities. Computer-assisted design (CAD) and computer assisted manufacturing (CAM) are used to describe the 3D planning and manufacturing of the product. The planning and manufacturing of 3D surgical guides and reconstruction implants is performed almost exclusively by engineers. As technology advances and software interfaces become more user-friendly, it raises a question regarding the possibility of transferring the planning and manufacturing to the clinician. The reasons for such a shift are clear: the surgeon has the idea of what he wants to design, and he also knows what is feasible and could be used in the operating room. It allows him to be prepared for any scenario/unexpected results during the operation and allows the surgeon to be creative and express his new ideas using the CAD software. The purpose of this method is to provide clinicians with the ability to create their own surgical guides and reconstruction implants. In this manuscript, a detailed protocol will provide a simple method for segmentation using segmentation software and implant planning using a 3D design software. Following the segmentation and stl file production using segmentation software, the clinician could create a simple patient specific reconstruction plate or a more complex plate with a cradle for bone graft positioning. Surgical guides can be created for accurate resection, hole preparation for proper reconstruction plate positioning or for bone graft harvesting and re-contouring. A case of lower jaw reconstruction following plate fracture and nonunion healing of a trauma sustained injury is detailed.

This protocol describes the use of 3D planning and printing for reconstruction of bony defects. We use segmentation tools to create 3D models followed by 3D design software to create patient specific implants for reconstruction purposes concomitant to ablative surgery or as a second stage.

We are in the midst of the 3D era in most aspects of life, and especially in medicine. The surgical discipline is one of the major players in the medical ...

Vacuum-Sealed Hot Water Bath Immersion for the Preparation of Anatomical and Surgical Cadaveric Bone Models

Bone models serve many purposes, including improving anatomical understanding, preoperative surgical planning, and intraoperative referencing. Several techniques for the maceration of soft tissues have been described, mainly for forensic analysis. For clinical research and medical use, these methods have been superseded by three-dimensional (3D) printed models, which require substantial equipment and expertise, and are costly. Here, cadaveric sheep vertebral bone was cleaned by vacuum sealing the specimen with commercial dishwashing detergent, immersing in a hot water bath, and subsequently manually removing the soft tissue. This eliminated the disadvantages of the previously existing maceration methods, such as the existence of foul odors, usage of hazardous chemicals, substantial equipment, and high costs. The described technique produced clean, dry samples while maintaining anatomical detail and structure to accurately model the osseous structures that can be useful for preoperative planning and intraoperative referencing. The method is simple, low-cost, and effective for bone model preparation for education and surgical planning in veterinary and human medicine.

The present protocol describes the maceration and cleaning of cadaveric bone with a vacuum-sealed, hot water bath immersion technique. This is a low-cost, safe, and effective method to produce anatomical specimens for surgical planning and medical education as an alternative to three-dimensional (3D) printed models.

Bone models serve many purposes, including improving anatomical understanding, preoperative surgical planning, and intraoperative referencing. Several ...

A Personalized 3D-Printed Model for Preoperative Evaluation in Thyroid Surgery

The anatomic structure of the surgical area of thyroid cancer is complex. It is very important to comprehensively and carefully evaluate the tumor location and its relation with the capsule, trachea, esophagus, nerves, and blood vessels before operation. This paper introduces an innovative 3D-printed model establishment method based on computerized tomography (CT) DICOM images. We established a personalized 3D-printed model of the cervical thyroid surgery field for each patient who needed thyroid surgery to help clinicians evaluate the key points and difficulties of the surgery and select the operation methods of key parts as a basis. The results showed that this model is conducive to preoperative discussion and the formulation of operation strategies. In particular, as a result of the clear display of the recurrent laryngeal nerve and parathyroid gland locations in the thyroid operation field, injury to them can be avoided during surgery, the difficulty of thyroid surgery reduced, and the incidence of postoperative hypoparathyroidism and complications related to recurrent laryngeal nerve injury reduced too. Moreover, this 3D-printed model is intuitive and aids communication for the signing of informed consent by patients before surgery.

Here, a new method of establishing a personalized 3D-printed model for preoperative evaluation of thyroid surgery is proposed. It is conducive to preoperative discussion, reducing the difficulty of thyroid surgery.

The anatomic structure of the surgical area of thyroid cancer is complex. It is very important to comprehensively and carefully evaluate the tumor ...

Biomechanical Analysis of Adjacent Segments after Spinal Fusion Surgery Using a Geometrically Parametric Patient-Specific Finite Element Model

This study aimed to perform a mechanical analysis of adjacent segments after spinal fusion surgery using a geometrically parametric patient-specific finite element model to elucidate the mechanism of adjacent segment degeneration (ASD), thereby providing theoretical evidence for early disease prevention. Fourteen parameters based on patient-specific spinal geometry were extracted from a patient's preoperative computed tomography (CT) scan, and the relative positions of each spinal segment were determined using the image match method. A preoperative patient-specific model of the spine was established through the above method. The postoperative model after L4-L5 posterior lumbar interbody fusion (PLIF) surgery was constructed using the same method except that the lamina and intervertebral disc were removed, and a cage, 4 pedicle screws, and 2 connecting rods were inserted. Range of motion (ROM) and stress changes were determined by comparing the values of each anatomical structure between the preoperative and postoperative models. The overall ROM of the lumbar spine decreased after fusion, while the ROM, stress in the facet joints, and stress in the intervertebral disc of adjacent segments all increased. An analysis of the stress distribution in the annulus fibrosus, nucleus pulposus, and facet joints also showed that not only was the maximum stress in these tissues elevated, but the areas of moderate-to-high stress were also expanded. During torsion, the stress in the facet joints and annulus fibrosus of the proximal adjacent segment (L3-L4) increased to a larger extent than that in the distal adjacent segment (L5-S1). While fusion surgery causes an overall restriction of motion in the lumbar spine, it also causes more load sharing by the adjacent segments to compensate for the fused segment, thus increasing the risk of ASD. The proximal adjacent segment is more prone to degeneration than the distal adjacent segment after spinal fusion due to the significant increase in stress.

Here, we used a patient-specific finite element model to analyze the mechanical changes in adjacent segments after spinal fusion surgery. The results showed that fusion surgery reduced the overall motion of the lumbar spine but increased the load on and stress in adjacent segments, especially the proximal segment.

This study aimed to perform a mechanical analysis of adjacent segments after spinal fusion surgery using a geometrically parametric patient-specific ...