Current status and challenges of Additive manufacturing in orthopaedics: An overview

Additive manufacturing is a rapidly emerging technology which is being successfully implemented in the various field of medicine as well as in orthopaedics, where it has applications in reducing cartilage defects and treatments of bones. The technology helps through systematic collection of information about the shape of the "defects" and precise fabrication of complex 3D constructs such as cartilage, heart valve, trachea, myocardial bone tissue and blood vessels. In this paper, a large number of the relevant research papers on the additive manufacturing and its application in medical specifically orthopaedics are identified through Scopus had been studied using Bibliometric analysis and application analysis is undertaken. The bibliometric analysis shows that there is an increasing trend in the research reports on additive manufacturing applications in the field of orthopaedics. Discussions are on using technological advancement like scanning techniques and various challenges of the orthopaedic being met by additive manufacturing technology. For patient-specific orthopaedic applications, these techniques incorporate clinical practice and use for effective planning. 3D printed models printed by this technology are accepted for orthopaedic surgery such as revision of lumbar discectomy, pelvic surgery and large scapular osteochondroma. The applications of additive manufacturing in orthopaedics will experience a rapid translation in future. An orthopaedic surgeon can convert need/idea into a reality by using computer-aided design (CAD) software, analysis software to facilitate the manufacturing. Thus, AM provides a comprehensive opportunity to manufacture orthopaedic implantable medical devices.     

肝退变结节的病理学改变及CT、MRI表现

肝细胞肝癌及胆管细胞癌均可在退变结节的基础上发展形成，因此及早、准确的诊断肝退变结节具有积极的临床意义。本文通过分析肝退变结节的CT、MRI表现及病理学改变，以期提高对肝退变结节的诊断水平。     

冠状动脉心肌桥的临床特点与治疗

目的探讨冠状动脉心肌桥的冠脉造影特点、临床意义及治疗方法。方法回顾性分析293例冠状动脉造影中检出的8例心肌桥患者的临床资料。结果共检出心肌桥8例,均位于前降支,心肌桥发生率为2.7%,心肌桥长度8～25mm,平均14.5mm。依据Nobel分级法,Ⅰ级3例,Ⅱ级4例,Ⅲ级1例。1例Ⅲ级患者同时并发冠脉粥样硬化,病变位于回旋支中段,狭窄<50%。8例患者应用β受体阻滞剂或钙拮抗剂治疗后症状均明显缓解。结论选择性冠脉造影可用于心肌桥的诊断,心肌桥可能引起心肌缺血表现,应用β受体阻滞剂或钙拮抗剂等药物治疗有效。     

Robust rigid registration of retinal angiograms through optimization

Retinal fundus photographs are employed as standard diagnostic tools in ophthalmology. Serial photographs of the flow of fluorescein and indocyanine green (ICG) dye are used to determine the areas of the retinal lesions. For objective measurements of features, the registration of the images is a necessity. In this paper, we employ optimization techniques for registration with the help of 2-parameter translational motion model of retinal angiograms, based on non-linear pre-processing (Wiener filtering and morphological gradient) and computation of the similarity criteria for the alignment of the two gradient images for any given rigid transformation. The optimization methods are effectively employed to minimize the similarity criterion.

The presence of noise, the variations in the background and the temporal variation of the fluorescence level pose serious problems in obtaining a robust registration of the retinal images. Moreover, local search strategies are not robust in the case of ICG angiograms, even if one uses a multiresolution approach.

The present work makes a systematic comparison of different optimization techniques, namely the minimization method derived from the optical flow formulation, the Nelder-Mead local search and the HCIAC ant colony metaheuristic, each optimizing a similarity criterion for the gradient images. The impact of the resolution and median filtering of gradient image is studied and the robustness of the approaches is tested through experimental studies, performed on macular fluorescein and ICG angiographies.

Our proposed optimization techniques have shown interesting results especially for high resolution difficult registration problems. Moreover, this approach seems promising for affine (6-parameter motion model) or elastical registrations.     

64层螺旋CT在糖尿病下肢动脉硬化闭塞症中的诊断价值

目的评价64层螺旋CT下肢动脉成像在诊断糖尿病下肢动脉硬化闭塞症中的临床价值。方法对90例可疑下肢血管病变的Ⅱ型糖尿病患者进行64层螺旋CT血管造影检查,对所有扫描原始数据行容积再现(VR),最大密度投影(M IP),冠状、矢状面多平面重组(MPR)以及曲面重建(CPR)。结果64层螺旋CT下肢血管造影检查可以清晰显示自髂总至足背整个动脉系统病变的准确部位、范围及侧枝血管。90例患者中67例(77%)患者血管呈不同程度粥样硬化表现。其中轻或中度狭窄49例(56.3%),重度狭窄18例(20.7%),7例(8%)完全闭塞患者可见侧枝循环血管形成。结论64层螺旋CT下肢血管造影,对糖尿病下肢动脉硬化闭塞症的诊断和治疗具有重要价值。     

症状性大脑中动脉缺血患者脑血管储备能力的CT灌注成像研究

目的采用5％CO2吸入CT灌注成像研究症状性大脑中动脉（MCA）缺血患者MCA分布区脑血管储备能力。资料与方法临床诊断为症状性MCA缺血且无心、肺疾病患者20例，基础态CT灌注成像TTP参数图显示有MCA供血区TTP延长。首先进行常规脑灌注CT检查（基础态）；20min后，面罩吸入5％CO2，持续吸入2min后再次行脑灌注CT检查（激发态）。感兴趣层面选择基底节层面和放射冠层面，层厚10mm。计算机后处理获得脑血流量（CBF）参数图后，于MCA分布区皮层多点手绘感兴趣区，分别计算双侧皮层CBF，计算双侧CBF变化率r=（CBF激发态-CBF基础态）／CBF基础态×100％；比较双侧激发后CBF改变，分析患侧MCA分布区脑血管储备能力。结果患侧MCA分布区皮层CBF明显低于健侧。健侧MCA分布区基础态和激发态CBF可见不同程度的改变：升高17例，降低3例。对17例激发后升高的患者进行分析，根据计算将患侧CO：激发反应分为：Ⅰ型，激发后CBF升高；Ⅱ型，激发后CBF变化不明显；Ⅲ型，激发后CBF降低。结论5％CO2吸入CT灌注成像激发试验可以评估脑血管储备能力，具有重要的临床价值。     

数字减影脑血管造影对原发性脑室出血的病因诊断价值

目的探讨DSA在原发性脑室出血(PIVH)原发病因检出中的应用价值。方法回顾性分析25例原发性脑室出血患者的DSA检查结果。结果25例患者中检出AVM8例,MoyaMoya病3例,颅内动脉瘤3例,海绵状血管瘤1例,造影阴性10例。结论DSA检查对甄别原发性脑室出血的病因具有重要的诊断意义,对有条件的PIVH病例均应行DSA检查以明确病因,作进一步病因治疗。     

原发性肝癌的彩色多普勒及三维血流能量成像特征及其临床意义

目的:探讨三维血流能量成像(3D-CPA)和彩色多普勒血流成像(CDFI)的临床应用价值。方法:对47例原发性肝癌的病灶进行二维、CDFI及3D-CPA的检查,比较CDFI及3D-CPA显示肿瘤瘤内或瘤周血流多普勒信号丰富程度及血管分布类型,并检测肿瘤的血流参数。结果:3D-CPA显示肿瘤血流分布丰富程度及血管分布类型与CDFI均有显著性差异(均P<0.05),CDFI均可探及肿瘤的搏动性动脉血流,其中,收缩期峰值血流速度(PSV)为43~157cm/s,阻力指数(RI)为0.49~0.82,大于0.65者45例。结论:3D-CPA结合彩色多普勒血流参数的检测可作为临床评价原发性肝癌血供及血管分布的常规检查方法。