3D打印技术在先天性心脏病伴气管软化诊断与治疗中的应用

目的:运用3D打印技术建立儿童先天性心脏病伴气管软化模型,探讨3D打印建模对于临床诊断和治疗方案制定的意义。 方法:1例先天性心脏病伴气管软化的患儿,行容积螺旋穿梭技术（VHS）CT扫描后获得影像资料;将CT图像导入Mimics 17.0软件并对气管区域进行图像重建后处理,得到气管三维重建模型;再运用3-Matic10.0软件对三维模型进行网格优化操作并保存成STL格式;最后将数据导入Objet 260 3D打印机打印出三维模型。 结果:利用3D打印构建了患儿吸气相和呼气相气管模型,与气管镜检查的结果一致。 结论:通过3D打印技术打印了患儿的全尺寸气管模型,给先天性心脏病伴气管软化的临床诊断和治疗予以有效的协助和指导。     

Hydrogels as extracellular matrices for skeletal tissue engineering: state-of-the-art and novel application in organ printing

Organ printing, a novel approach in tissue engineering, applies layered computer-driven deposition of cells and gels to create complex 3-dimensional cell-laden structures. It shows great promise in regenerative medicine, because it may help to solve the problem of limited donor grafts for tissue and organ repair. The technique enables anatomical cell arrangement using incorporation of cells and growth factors at predefined locations in the printed hydrogel scaffolds. This way, 3-dimensional biological structures, such as blood vessels, are already constructed. Organ printing is developing fast, and there are exciting new possibilities in this area. Hydrogels are highly hydrated polymer networks used as scaffolding materials in organ printing. These hydrogel matrices are natural or synthetic polymers that provide a supportive environment for cells to attach to and proliferate and differentiate in. Successful cell embedding requires hydrogels that are complemented with biomimetic and extracellular matrix components, to provide biological cues to elicit specific cellular responses and direct new tissue formation. This review surveys the use of hydrogels in organ printing and provides an evaluation of the recent advances in the development of hydrogels that are promising for use in skeletal regenerative medicine. Special emphasis is put on survival, proliferation and differentiation of skeletal connective tissue cells inside various hydrogel matrices.     

Challenges in creating dissectible anatomical 3D prints for surgical teaching

Three‐dimensional (3D) printing, or additive manufacturing, is now a widely used tool in pre‐operative planning, surgical teaching and simulator training. However, 3D printing technology that produces models with accurate haptic feedback, biomechanics and visuals for the training surgeon is not currently available. Challenges and opportunities in creating such surgical models will be discussed in this review paper. Surgery requires proper tissue handling as well as knowledge of relevant anatomy. To prepare doctors properly, training models need to take into account the biomechanical properties of the anatomical structures that will be manipulated in any given operation. This review summarises and evaluates the current biomechanical literature as it relates to human tissues and correlates the impact of this knowledge on developing high fidelity 3D printed surgical training models. We conclude that, currently, a printer technology has not yet been developed which can replicate many of the critical qualities of human tissue. Advances in 3D printing technology will be required to allow the printing of multi‐material products to achieve the mechanical properties required.     

3D printing of composite calcium phosphate and collagen scaffolds for bone regeneration

Low temperature 3D printing of calcium phosphate scaffolds holds great promise for fabricating synthetic bone graft substitutes with enhanced performance over traditional techniques. Many design parameters, such as the binder solution properties, have yet to be optimized to ensure maximal biocompatibility and osteoconductivity with sufficient mechanical properties. This study tailored the phosphoric acid-based binder solution concentration to 8.75 wt% to maximize cytocompatibility and mechanical strength, with a supplementation of Tween 80 to improve printing. To further enhance the formulation, collagen was dissolved into the binder solution to fabricate collagen-calcium phosphate composites. Reducing the viscosity and surface tension through a physiologic heat treatment and Tween 80, respectively, enabled reliable thermal inkjet printing of the collagen solutions. Supplementing the binder solution with 1–2 wt% collagen significantly improved maximum flexural strength and cell viability. To assess the bone healing performance, we implanted 3D printed scaffolds into a critically sized murine femoral defect for 9 weeks. The implants were confirmed to be osteoconductive, with new bone growth incorporating the degrading scaffold materials. In conclusion, this study demonstrates optimization of material parameters for 3D printed calcium phosphate scaffolds and enhancement of material properties by volumetric collagen incorporation via inkjet printing.     

三维重建及3D打印技术在骨盆三维特征测量准确性研究

目的　研究分析尸体骨盆与其三维重建数字化模型及3D打印实体模型的三维特征测量结果差异。 方法　选择1具中年男性骨盆标本,根据骨盆的生理学结构特点在骨盆标本表面选取并固定共计14个特征点,并使用三坐标仪测量并记录特征点的三维坐标;使用CT设备对固定了特征点的骨盆标本进行1.0 mm的断层扫描;使用三维医学图像软件（Delta Medical Studio,DMS）对获取的扫描图像进行三维重建,并记录特征点的三维坐标;使用3D打印设备（熔融沉积成型,FDM）及光固化成型（Stereo Lithography Appearance,SLA）打印三维重建模型,三坐标仪测量记录特征点的三维坐标;通过记录的三维坐标分别计算尸体标本、数字模型、3D打印实体模型的特征点之间的距离及夹角;从最大误差、平均误差、t值验证等角度分析三组数据的误差情况。 结果　三维重建数字化骨盆模型的特征测量距离的平均误差约为0.5 mm,角度平均误差约为0.35 o;3D打印模型相对于骨盆标本的距离测量的平均误差约为0.8~1.1 mm,角度平均误差约为0.4°~0.5°。 结论 三维重建模型和3D打印实体模型对于骨盆术前的参考及测量精度方面具备可靠性,可根据实际需求选择3D打印模型作为骨盆术前规划的参考。     

三维重建及3D打印技术在骨盆三维特征测量准确性研究

目的　研究分析尸体骨盆与其三维重建数字化模型及3D打印实体模型的三维特征测量结果差异。 方法　选择1具中年男性骨盆标本,根据骨盆的生理学结构特点在骨盆标本表面选取并固定共计14个特征点,并使用三坐标仪测量并记录特征点的三维坐标;使用CT设备对固定了特征点的骨盆标本进行1.0 mm的断层扫描;使用三维医学图像软件（Delta Medical Studio,DMS）对获取的扫描图像进行三维重建,并记录特征点的三维坐标;使用3D打印设备（熔融沉积成型,FDM）及光固化成型（Stereo Lithography Appearance,SLA）打印三维重建模型,三坐标仪测量记录特征点的三维坐标;通过记录的三维坐标分别计算尸体标本、数字模型、3D打印实体模型的特征点之间的距离及夹角;从最大误差、平均误差、t值验证等角度分析三组数据的误差情况。 结果　三维重建数字化骨盆模型的特征测量距离的平均误差约为0.5 mm,角度平均误差约为0.35 o;3D打印模型相对于骨盆标本的距离测量的平均误差约为0.8~1.1 mm,角度平均误差约为0.4°~0.5°。 结论 三维重建模型和3D打印实体模型对于骨盆术前的参考及测量精度方面具备可靠性,可根据实际需求选择3D打印模型作为骨盆术前规划的参考。     

3D打印颅骨在颅底解剖教学中的应用

目的旨在探究3D打印技术制作解剖教具应用于医学解剖教育的可行性。方法用CT扫描获取大体颅骨标本影像数据,重建并采用3D打印技术构建颅骨模型。招募26名北京协和医学院三年级医学生,采用3D打印颅骨模型进行颅底解剖学习,并通过主观评价问卷对其在解剖教学中的实用性进行评价。结果 57%试验参与者认为3D打印颅骨能够完整呈现颅底解剖结构,超过90%参与者同意3D打印模型有助于空间理解和解剖学习,88%参与者认为3D打印颅骨能够解决大体解剖标本带来的伦理学问题,84%参与者赞同将3D打印模型应用于颅底解剖教学。结论 3D打印模型在解剖教学中效果得到了肯定,3D打印技术在医学教育中的进一步应用亟待展开。     

3D Printed Modeling of the Mitral Valve for Catheter-Based Structural Interventions

As catheter-based structural heart interventions become increasingly complex, the ability to effectively model patient-specific valve geometry as well as the potential interaction of an implanted device within that geometry will become increasingly important. Our aim with this investigation was to combine the technologies of high-spatial resolution cardiac imaging, image processing software, and fused multi-material 3D printing, to demonstrate that patient-specific models of the mitral valve apparatus could be created to facilitate functional evaluation of novel trans-catheter mitral valve repair strategies. Clinical 3D transesophageal echocardiography and computed tomography images were acquired for three patients being evaluated for a catheter-based mitral valve repair. Target anatomies were identified, segmented and reconstructed into 3D patient-specific digital models. For each patient, the mitral valve apparatus was digitally reconstructed from a single or fused imaging data set. Using multi-material 3D printing methods, patient-specific anatomic replicas of the mitral valve were created. 3D print materials were selected based on the mechanical testing of elastomeric TangoPlus materials (Stratasys, Eden Prairie, Minnesota, USA) and were compared to freshly harvested porcine leaflet tissue. The effective bending modulus of healthy porcine MV tissue was significantly less than the bending modulus of TangoPlus (p < 0.01). All TangoPlus varieties were less stiff than the maximum tensile elastic modulus of mitral valve tissue (3697.2 ± 385.8 kPa anterior leaflet; 2582.1 ± 374.2 kPa posterior leaflet) (p < 0.01). However, the slopes of the stress-strain toe regions of the mitral valve tissues (532.8 ± 281.9 kPa anterior leaflet; 389.0 ± 156.9 kPa posterior leaflet) were not different than those of the Shore 27, Shore 35, and Shore 27 with Shore 35 blend TangoPlus material (p > 0.95). We have demonstrated that patient-specific mitral valve models can be reconstructed from multi-modality imaging datasets and fabricated using the multi-material 3D printing technology and we provide two examples to show how catheter-based repair devices could be evaluated within specific patient 3D printed valve geometry. However, we recognize that the use of 3D printed models for the development of new therapies, or for specific procedural training has yet to be defined.     

Effectiveness of personalized 3D printed models for patient education in degenerative lumbar disease

ObjectiveThree-dimensional printing may play an important role in patients’ education. The objective of this study was to assess the effectiveness of personalized 3D printed models for increasing patient understanding of their medical condition and surgical plan.MethodsForty-five patients with degenerative lumbar diseases were randomized by block design into three groups: educational program presented by CT & MRI imaging (care-as-usual), 3D reconstructions, or personalized 3D printed models. Patients’ level of understanding and satisfaction were evaluated by two questionnaires one day after education.ResultsPatients educated with personalized 3D printed models demonstrated an expanded level of understanding than patients educated with CT & MRI imaging (care-as-usual) (P ＜ 0.05) and 3D reconstructions (P ＜ 0.05). Personalized 3D printed models also resulted in a higher degree of patient satisfaction (P ＜ 0.05).ConclusionsPersonalized 3D printed models and 3D reconstructions can simplify and enhance understanding of lumbar anatomy, physiology, and patients’ disease and surgical plan. Personalized 3D printed models also enhance patients’ subjective satisfaction.Practice implicationsPersonalized 3D printed models for patient education are feasible and could be generalized for degenerative lumbar diseases.     

Development of patient-specific three-dimensional pediatric cardiac models

The availability of algorithms to create three-dimensional (3D) models from medical images has made it possible to render and build patient-specific reconstructions of individual body parts. In the present study, this technology was used to create 3D models of pediatric hearts for use in medical device development. Digital models were created using CT datasets of pediatric hearts and commercially available 3D image processing software. Using this software, stacked CT data were viewed, and pixels representing the heart and rib cage were selected and rendered as 3D models. Stereolithography and 3D printing technology were used to create rigid and flexible physical heart models (biomodels) from the digital models. Twelve on-screen models of the thorax and cardiac structures were created from cardiac CT scans obtained from 11 patients with and without congenital heart disease (median age, 3 years; range, 2 days to 13 years). Rigid and flexible physical heart models were generated from the digital models to provide tactile and visual information. 3D models of pediatric cardiac and chest anatomy provide enhanced understanding and tactile representation of complex anatomy. Precise representation of the spatial relationships between anatomic structures is particularly useful during the development and placement of medical devices.     

3D打印技术在股骨髁上骨折医患沟通中的效果研究

目的　探讨Mimics18.0软件数字化设计结合3D打印骨折模型进行手术规划,术前模拟手术,辅助治疗复杂型股骨髁上骨折内固定及在医患沟通环节的效果研究。 方法　筛选10例复杂型股骨髁上骨折患者,将患者的骨折部分及全套内固定物的薄层CT数据导入Mimics 18.0软件,进行骨折三维建模、骨折块虚拟复位、建立股骨髁上骨折内固定物标准件库、选取最佳匹配的钢板及螺钉。3D打印出患者1:1的股骨髁上骨折实体模型, 术前应用3D打印模型与患者及其家属沟通并进行3D打印模型的效度验证。让患者及其家属直接接触骨折3D模型并观看在模型上按照数字化设计进行模拟手术-将股骨髁上重建板的位置、钉道长度和方向同数字化设计比较,确定术中使用的钢板及螺钉。最后,按照术前模拟演练进行实际手术骨折复位、钢板内固定。 结果　术前应用3D模型获得了良好的沟通效果,患者及其家属理解度和满意度高。应用3D打印技术模拟手术共植入1块锁定钢板和8枚螺钉,钢板植入的位置、螺钉植入的方向均与数字化术前设计高度一致,钉道长度与数字化术前设计比较无显著性差异(P>0.05)。实际手术与模拟手术的手术效果一致。 结论　数字化设计结合3D打印技术在医患沟通方面效果显著,且实现了复杂型股骨髁上骨折的个体化、精准化治疗,明显减少了患者的术中出血量,缩短了患者的康复周期。     

3D printing for preoperative planning and surgical training: a review

Surgeons typically rely on their past training and experiences as well as visual aids from medical imaging techniques such as magnetic resonance imaging (MRI) or computed tomography (CT) for the planning of surgical processes. Often, due to the anatomical complexity of the surgery site, two dimensional or virtual images are not sufficient to successfully convey the structural details. For such scenarios, a 3D printed model of the patient’s anatomy enables personalized preoperative planning. This paper reviews critical aspects of 3D printing for preoperative planning and surgical training, starting with an overview of the process-flow and 3D printing techniques, followed by their applications spanning across multiple organ systems in the human body. State of the art in these technologies are described along with a discussion of current limitations and future opportunities.     

Viability and electrophysiology of neural cell structures generated by the inkjet printing method

Complex cellular patterns and structures were created by automated and direct inkjet printing of primary embryonic hippocampal and cortical neurons. Immunostaining analysis and whole-cell patch-clamp recordings showed that embryonic hippocampal and cortical neurons maintained basic cellular properties and functions, including normal, healthy neuronal phenotypes and electrophysiological characteristics, after being printed through thermal inkjet nozzles. In addition, in this study a new method was developed to create 3D cellular structures: sheets of neural cells were layered on each other (layer-by-layer process) by alternate inkjet printing of NT2 cells and fibrin gels. These results and findings, taken together, show that inkjet printing is rapidly evolving into a digital fabrication method to build functional neural structures that may eventually find applications in neural tissue engineering.     

3D打印技术在皮肤癌近距离放疗中的初步应用

目的:探讨3D打印技术在皮肤癌高剂量率近距离治疗个体化施源器模板制作中的应用。方法:根据1例基底细胞 皮肤癌患者的定位CT图像进行术前计划设计，然后根据患者轮廓和术前计划中预设管道位置完成3D模板打印。将打印 好的模板置于病灶处并加以固定，再次进行CT扫描，将两次的CT图像进行融合匹配，以确定管道位置重合程度。结果: 3D打印模板与患者外轮廓高度贴合，实际治疗中，3D打印模板中施源器管道位置可与预计划中的施源器管道位置完成 匹配重合，提高了靶区覆盖率。结论:对于位置轮廓曲面角度大的皮肤癌病变，根据术前计划进行3D打印模板辅助近距 离治疗可使病灶较好地达到处方剂量。临床疗效与不良反应尚需进一步观察。     

3D Printing of Tough Gels Having Tunable Elastic Modulus from the Same Pre‐Gel Solution

A gel forming method with sections with different elastic modulus is developed. Gels with hardness distribution are formed from one base gel material by adjusting the crosslinking density of the polymer network using a 3D gel printer. It is confirmed that hardness is arranged as designed by using mixing rules of composite materials. Furthermore, as a prototype of a practical gel application, a gel finger model having a soft‐fleshy part and a hard‐bony part is printed. 3D printing of an organ model that reproduces a realistic feel that takes not only the shape of the organ but also the distribution of hardness into consideration may become possible.     

TangoPlus扩张性分析及其在心血管模型中的可行性

目的:探讨TangoPlus FullCure 930w的扩张性,并评估其在心血管模型中的可行性。方法:根据心血管磁共振图像,利用3D打印对一名受试的降主动脉解剖结构进行建模,并使用TangoPlus进行快速原型。印刷该模型的壁厚分别为0.6、0.7、0.8、1.0和1.5 mm,血管腔保持恒定;且模型分别以垂直和水平方向印刷,共得到10个样本。通过监测压力变化,同时逐渐增加和减少内部体积,从而进行依从性试验。生产出一种适合连接在体外试验模拟循环回路中的患者特异性顺应性主动脉模型。打印出需行肺动脉瓣置换术患者的右心室流出道（RVOT）,以便对器械插入进行物理测试并评估患者经皮肺动脉瓣介入的适用性。结果:对于壁厚0.6 mm,材料的扩张性为（6.5×10-3） mmHg-1;对于壁厚1.5 mm,材料的扩张性为（3.0×10-3） mmHg-1。垂直方向打印的型号相比水平方向的型号更符合要求。顺应性主动脉发育不全的快速原型和RVOT解剖模型都是可行的;器械插入RVOT模型成功。结论:TangoPlus适用于制造动脉模型,与PolyJet打印兼容,确保具有代表性的解剖结构建模,制造快速且廉价。该材料还可以用于探索非均匀壁厚印刷模型的吸引力。然而,该材料似乎太硬,无法模拟更符合要求的全身性静脉系统。     

The three-dimensional printing renaissance of individualized anatomical modeling: Are we repeating history?

Three-dimensional (3D) printing has revolutionized individualized medicine for patient-specific anatomical modeling and surgical planning. The surge of investigations in model creation for preoperative assessments and patient education has demonstrated improvements in both operative factors and patient satisfaction. In addition, recent technologic advances in 3D printing techniques have provided a resource to create visually pleasing models with chromatic cues for segmentation of adjacent structures. Despite these advances, an important consideration that has yet to be addressed is the quality of representation of the not only the form of structures created, but also the functional relationships of each structure. Jean François Fernel (1497–1558 AD) recognized a similar trend in anatomic innovation over 500 years ago, and sparked a series of texts that challenged the superficial anthropocentric views of the time and led to the foundation of physiologic principles that shaped modern medical philosophy. Accurately generating anatomical structures are directly related to discerning true physiologic function, and a comprehensive understanding of both is essential to hold accountability in fidelity for individualized 3D printing.     

Nerves of Steel: a Low-Cost Method for 3D Printing the Cranial Nerves

Steady-state free precession (SSFP) magnetic resonance imaging (MRI) can demonstrate details down to the cranial nerve (CN) level. High-resolution three-dimensional (3D) visualization can now quickly be performed at the workstation. However, we are still limited by visualization on flat screens. The emerging technologies in rapid prototyping or 3D printing overcome this limitation. It comprises a variety of automated manufacturing techniques, which use virtual 3D data sets to fabricate solid forms in a layer-by-layer technique. The complex neuroanatomy of the CNs may be better understood and depicted by the use of highly customizable advanced 3D printed models. In this technical note, after manually perfecting the segmentation of each CN and brain stem on each SSFP-MRI image, initial 3D reconstruction was performed. The bony skull base was also reconstructed from computed tomography (CT) data. Autodesk 3D Studio Max, available through freeware student/educator license, was used to three-dimensionally trace the 3D reconstructed CNs in order to create smooth graphically designed CNs and to assure proper fitting of the CNs into their respective neural foramina and fissures. This model was then 3D printed with polyamide through a commercial online service. Two different methods are discussed for the key segmentation and 3D reconstruction steps, by either using professional commercial software, i.e., Materialise Mimics, or utilizing a combination of the widely available software Adobe Photoshop, as well as a freeware software, OsiriX Lite.     

构建3D打印牙齿模型及其形态仿真性研究

目的　应用3D打印技术构建出3D打印牙齿模型以替代离体牙,并通过形态仿真性研究来探讨3D打印牙齿模型在临床应用前景。 方法　选择合适的3D打印材料及设备并测试材料根管成型能力。用锥形束CT筛选出完整的单根管前牙、双根管前磨牙、双根管磨牙、三根管磨牙,再行显微CT扫描并数字化三维重建,获得3D打印牙齿模型。对模型二次扫描并重建,利用Geomagic Qualify 11与原牙齿三维模型进行三维比较,通过检测模型与原牙齿的差异来分析不同材料3D打印牙齿模型的精确度。 结果　成功构建出3D打印牙齿模型。在表面形态上,Wic300a模型组绝对偏差值为（0.008121±0.0480）mm,E-Dent模型组为（0.009554±0.0526）mm;髓腔形态上,Wic300a模型组绝对偏差值为（0.045181±0.1022）mm,E-Dent模型组为（0.056953±0.1995）mm。 结论　3D打印牙齿模型离体牙仿真度较高,3D打印牙齿模型可用于口内操作培训及术前模拟等。