基于最大互信息的医学图像配准算法

本文提出一种新的基于轮廓提取和最大互信息理论的医学图像配准的算法。该算法克服了在配准过程中存在鲁棒性因素、出现误配情况及互信息单一的利用图像灰度信息的局限性,将边缘检测与互信息相结合,提高了原有算法的性能,可较准确地完成图像配准任务。本文并对提出的配准算法进行了Matlab仿真实验,对仿真结果进行分析。     

New registration algorithm for determining 3D knee kinematics using CT and single‐plane fluoroscopy with improved out‐of‐plane translation accuracy

To understand the kinematic effects of surgery, arthroplasty or conservative treatments, a noninvasive system to capture accurate 3D imaging of functional activities in prospective, controlled studies is required. To provide such a technique, a new algorithm was developed to register 3D CT data of normal bones to the same bones in a 2D fluoroscopy frame. The algorithm produces a digitally reconstructed radiograph (DRR) from the CT data and then filters this to produce an edge‐enhanced image. The resulting image is then registered with an edge‐enhanced version of the fluoroscopy frame using a new similarity measure called Cross‐Correlation Residual Entropy (CCRE). The system was evaluated by implanting tantalum beads into three cadaveric knees to act as fiducial markers. The knees were flexed between 0° and 70°, and single‐plane fluoroscopy data of the knees were acquired. CT data of the femur and tibia were then individually registered to the fluoroscopy images. No significant measurement bias was observed, and the standard deviation of the error in bead positions was 0.38 mm for in‐plane translation and 0.42 degrees for rotation. To determine the accuracy of the registration algorithm for out‐of‐plane translations, fluoroscopy frames were scaled in size by fixed increments; the average standard deviation of the errors for out‐of‐plane translation was 0.65 mm. The ability to obtain such accurate 3D motion data from a noninvasive technique will enable prospective, longitudinal, and controlled studies of reconstruction surgery, and conservative management of joint pathologies. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:334–340, 2010     

3D path planning for flexible needle steering in neurosurgery

Background: We propose a 3D path planning method to steer flexible needles along curved paths in the context of deep brain stimulation (DBS) procedures. Methods: Our approach is based on a rapidly exploring random tree strategy, and it takes into account constraints coming from anatomical obstacles and physical constraints dictated by flexible needle kinematics. The strategy is evaluated in simulation on a realistic 3D CAD model of the brain. Results: The subthalamic nucleus (STN) and the fornix can be reached along several curved paths from various entry points. As compared with the usual straight line path, these curved paths avoid tissue damage to important neural structures while allowing for a much greater selection of entry points. Conclusions: This path planning method offers alternative curved paths to reach DBS targets with flexible needles. The method potentially leads to safer paths and additional entry points capable of reaching the desired stimulation targets.     

3D preoperative planning for shoulder arthroplasty: an evaluation of different planning software systems

BackgroundOptimal glenoid component positioning in shoulder arthroplasty can sometimes be challenging. 3D preoperative planning and patient-specific instruments can help position the glenoid component more accurately. Multiple medical companies have developed their method of performing preoperative glenoid measurements. The goal of this study was to compare those different measurement techniques for inclination and version measurements.MethodsCT scans of 13 cadaveric shoulders were used for 3D analysis. All CT scans were sent to different companies that agreed to participate in this study. Each company was expected to report on their methods and measure the preoperative glenoid inclination and version. Furthermore, the researchers calculated preoperative inclination and version of these shoulders using 2 different methods. The measurements were statistically analyzed to determine differences between all methods in a pairwise manner.ResultsSix methods were evaluated in a pairwise manner, resulting in 15 pairs being analyzed. 10 pairs differed significantly for inclination (P < .008), and 4 pairs differed significantly for version (P < .008).ConclusionThere are significant differences between measurement techniques concerning preoperative glenoid inclination and version. The knowledge that different companies use different measurement techniques for preoperative 3D planning of shoulder surgery is essential and should be taken into account when using different planning systems.Level of evidenceLevel III; Study of Diagnostic Test     

Feature-invariant image registration method for quantification of surgical outcomes in patients with craniosynostosis: a preliminary study

Craniosynostosis consists of a premature fusion of the sutures in an infant skull that restricts skull and brain growth. During the last decades, there has been a rapid increase of fundamentally diverse surgical treatment methods. At present, the surgical outcome has been assessed using global variables such as cephalic index, head circumference, and intracranial volume. However, these variables have failed in describing the local deformations and morphological changes that may have a role in the neurologic disorders observed in the patients. This report describes a rigid image registration-based method to evaluate outcomes of craniosynostosis surgical treatments, local quantification of head growth, and indirect intracranial volume change measurements. The developed semiautomatic analysis method was applied to computed tomography data sets of a 5-month-old boy with sagittal craniosynostosis who underwent expansion of the posterior skull with cranioplasty. Quantification of the local changes between pre- and postoperative images was quantified by mapping the minimum distance of individual points from the preoperative to the postoperative surface meshes, and indirect intracranial volume changes were estimated. The proposed methodology can provide the surgeon a tool for the quantitative evaluation of surgical procedures and detection of abnormalities of the infant skull and its development.     

Intensity‐based 2D‐3D registration for an ACL reconstruction navigation system

To improve the positioning accuracy of tunnels for anterior cruciate ligament (ACL) reconstruction, we proposed an intensity‐based 2D‐3D registration method for an ACL reconstruction navigation system. Methods for digitally reconstructed radiograph (DRR) generation, similarity measurement, and optimization are crucial to 2D‐3D registration. We evaluated the accuracy, success rate, and processing time of different methods: (a) ray‐casting and splating were compared for DRR generation; (b) normalized mutual information (NMI), Mattes mutual information (MMI), and Spearman's rank correlation coefficient (SRC) were assessed for similarity between registrations; and (c) gradient descent (GD) and downhill simplex (DS) were compared for optimization. The combination of splating, SRC, and GD provided the best composite performance and was applied in an augmented reality (AR) ACL reconstruction navigation system. The accuracy of the navigation system could fulfill the clinical needs of ACL reconstruction, with an end pose error of 2.50 mm and an angle error of 2.74°.     

3D volume assessment techniques and computer-aided design and manufacturing for preoperative fabrication of implants in head and neck reconstruction

Cases in subdisciplines of craniomaxillofacial surgery--corrective jaw surgery, maxillofacial trauma, temporomandibular joint/skull base, jaw reconstruction, and postablative reconstruction-illustrate the ease of use, cost effectiveness, and superior results that can be achieved when using computer-assisted design and 3D volumetric analysis in preoperative surgical planning. This article discusses the materials and methods needed to plan cases, illustrates implementation of guides and implants, and describes postoperative analysis in relation to the virtually planned surgery.     

结合术前三维重建的腹腔镜肝切除术学习曲线研究

目的 分析结合术前三维重建的腹腔镜肝切除术的学习曲线。方法 回顾性分析2019年3月至2020年12月华西医院上锦分院普外一科单中心行腹腔镜肝切除术患者64例的临床资料,使用累计分析法分析成功实施手术患者的手术时间与手术难度评分的比值,并绘制学习曲线。结果 64例患者中3例中转开腹,61例完成腹腔镜肝切除术。所有患者术前行三维重建辅助手术。中位手术时间为185(100～150)min,中位难度评分为4(4～6)分。以手术时间与手术难度评分的比值绘制学习曲线,显示1～26例为上升期,27～41例为波动期,42例以后进入成熟期。成熟期手术难度评分明显高于上升期及波动期(P<0.05)。患者围手术期病死率1.6%(1/61),术后并发症总发生率为14.8%(9/61),其中出血发生率为4.9%(3/61),胆漏发生率为4.9%(3/61),肝功能不全发生率11.5%(7/61);术后中位住院时间6 d。结论 结合术前三维重建开展腹腔镜肝切除术安全可行,施行约40例以后可以渡过学习曲线,达到较稳定和熟练的程度。     

3D技术在中央型肝肿瘤术前规划中的临床应用

目的:探讨3D可视化技术在中央型肝肿瘤患者术前规划中的应用价值。方法:回顾性分析2016年1月—2017年11月28例采用3D可视化技术行术前评估的中央型肝肿瘤患者临床资料。术前患者获取二维CT图像,导入3D可视化软件中,分别对肝脏、肝动脉系统、门静脉系统、肝静脉系统及肿瘤行图像分割和3D重建,随后进行肝脏分段及中央型肝肿瘤分型、个体化体积计算;依据3D重建结果进行手术规划,选择合理的手术路径及方式。结果:28例患者均完成3D可视化模型的建立,3D技术可显示肝内各血管系统解剖、肿瘤具体部位、大小及毗邻关系,进行肝脏个体化分段及肝中叶肿瘤分型。患者全肝体积中位数为1532(1025~1864)m L,肝肿瘤体积466(45~558)m L,拟切除肝体积为595(108~806)m L。28例患者均行肿瘤根治性切除术,实际手术路径及方式与术前手术规划符合率100%。术中出血量和输血量中位数分别为700(100~2000)m L和600(0~1400)m L,输血率为71.42%(20/28),并发症发生率为28.57%(8/28),术后无严重肝功能不全病例,住院病死率为0。结论:3D可视化技术可以计算剩余肝脏体积,并可提高中央型肝肿瘤肝切除手术前规划的准确率及帮助术中精确操作。     

3D打印术前模拟手术固定辅助治疗胫骨平台陈旧骨折

目的 探讨3D打印术前模拟手术固定辅助治疗胫骨平台陈旧骨折的疗效.方法 对20例胫骨平台陈旧骨折患者术前采用3D打印等比例骨折模型,在模型上模拟骨折复位及固定.术后在X线片上测量胫骨平台内翻角(TPA)、股胫角(FTA)及内侧平台后倾角(PSA)评估骨折复位质量,末次随访时采用HSS膝关节功能评分评价疗效.结果 患者均...     

Virtual 3D planning of acetabular fracture reduction

Displaced acetabular fractures are best treated with open reduction to achieve anatomic reduction and maximize the chance of a good functional outcome. Because of the anatomic complexity and often limited visualization, fracture reduction can be difficult. Virtual planning software can allow the surgeon to understand the fracture morphology and to rehearse reduction maneuvers. The purpose of this study was to determine the effect of a novel virtual fracture reduction module on time and accuracy of reduction. Four acetabular fracture patterns were created in synthetic pelves, which were implanted with fiducial markers and were registered with CT scan. Ten surgeons used virtual fracture reduction software or conventional 2D planning methods and immediately reduced the fractures blindly in a viscous gel medium. 3D imaging was again performed and the accuracy of reduction was assessed. The average malreduction was significantly improved following planning with the virtual software compared to the standard technique. The time taken for reduction was also significantly less for two of the four fracture patterns. Virtual software may be useful for visualizing and planning treatment of fractures of the acetabulum, potentially leading to more accurate and efficient reductions, and may also be an effective educational tool. © 2007 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:547–552, 2008     

术前虚拟规划联合3D打印模板预塑形钢板治疗髋臼后壁骨折

目的:评估虚拟术前规划和3D打印模板预塑形钢板治疗髋臼后壁骨折的可行性和准确性。方法:回顾性分析2017年8月至2020年8月治疗的髋臼后壁骨折患者29例,根据是否采用术前虚拟规划和3D打印模板分为2组,3D打印组14例,男10例,女4例;年龄21～53岁;基于患者骨盆CT数据采用Mimics和3-Matic软件进行虚拟手术规划,虚拟复位骨折,设计后壁钢板模板及螺钉固定位置,模拟透视记录合适方位以指导术中透视,打印后壁钢板模板和带有后壁骨折块的钢板螺钉模型,然后根据模板预塑形钢板备用。常规组15例,男10例,女5例;年龄19～55岁;采用常规的方法术中折弯钢板适应骨折区域。比较两组术中出血量、手术时间、骨折复位质量和髋关节功能。结果:23例患者获得随访,时间12～30个月。两组患者骨折均愈合,愈合时间3～6个月。两组手术时间、术中出血量比较,差异均有统计学意义(P<0.05)。末次随访时髋关节功能Merle d’Aubign-Postel评分,3D打印组疼痛程度评分低于常规组(P<0.05);两组行走能力、髋关节活动度和总分比较,差异均无统计学意义(P>0.05)。3...     

Prediction of normal bone anatomy for the planning of corrective osteotomies of malunited forearm bones using a three‐dimensional statistical shape model

Corrective osteotomies of the forearm based on 3D computer simulation using contralateral anatomy as a reconstruction template is an approved method. Limitations are existing considerable differences between left and right forearms, and that a healthy contralateral anatomy is required. We evaluated if a computer model, not relying on the contralateral anatomy, may replace the current method by predicting the pre‐traumatic healthy shape. A statistical shape model (SSM) was generated from a set of 59 CT scans of healthy forearms, encoding the normal anatomical variations. Three different configurations were simulated to predict the pre‐traumatic shape with the SSM (cross‐validation). In the first two, only the distal or proximal 50% of the radius were considered as pathological. In a third configuration, the entire radius was assumed to be pathological, only the ulna being intact. Corresponding experiments were performed with the ulna. Accuracy of the prediction was assessed by comparing the predicted bone with the healthy model. For the radius, mean rotation accuracy of the prediction between 2.9 ± 2.2° and 4.0 ± 3.1° in pronation/supination, 0.4 ± 0.3° and 0.6 ± 0.5° in flexion/extension, between 0.5 ± 0.3° and 0.5 ± 0.4° in radial‐/ulnarduction. Mean translation accuracy along the same axes between 0.8 ± 0.7 and 1.0 ± 0.8 mm, 0.5 ± 0.4 and 0.6 ± 0.4 mm, 0.6 ± 0.4 and 0.6 ± 0.5 mm, respectively. For the ulna, mean rotation accuracy between 2.4 ± 1.9° and 4.7 ± 3.8° in pronation/supination, 0.3 ± 0.3° and 0.8 ± 0.6° in flexion/extension, 0.3 ± 0.2° and 0.7 ± 0.6° in radial‐/ulnarduction. Mean translation accuracy between 0.6 ± 0.4 mm and 1.3 ± 0.9 mm, 0.4 ± 0.4 mm and 0.7 ± 0.5 mm, 0.5 ± 0.4 mm and 0.8 ± 0.6 mm, respectively. This technique provided high accuracy, and may replace the current method, if validated in clinical studies. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2630–2636, 2017.

     

Virtual preoperative planning and 3D printing are valuable for the management of complex orthopaedic trauma

Purpose: The technology of 3D printing (3DP) exists for quite some time, but it is still not utilized to its full potential in the field of orthopaedics and traumatology, such as underestimating its worth in virtual preoperative planning (VPP) and designing various models, templates, and jigs. It can be a significant tool in the reduction of surgical morbidity and better surgical outcome avoiding various associated complications. Methods: An observational study was done including 91 cases of complex trauma presented in our institution requiring operative fixation. Virtual preoperative planning and 3DP were used in the management of these fractures. Surgeons managing these cases were given a set of questionnaire and responses were recorded and assessed as a quantitative data. Results: In all the 91 cases, where VPP and 3DP were used, the surgeons were satisfied with the outcome which they got intraoperatively and postoperatively. Surgical time was reduced, with a better outcome. Three dimensional models of complex fracture were helpful in understanding the anatomy and sketching out the plans for optimum reduction and fixation. The average score of the questionnaire was 4.5, out of a maximum of 6, suggesting a positive role of 3DP in orthopaedics. Conclusion: 3DP is useful in complex trauma management by accurate reduction and placement of implants, reduction of surgical time and with a better outcome. Although there is an initial learning curve to understand and execute the VPP and 3DP, these become easier with practice and experience.     

Reliability and accuracy of 3D preoperative planning software for glenoid implants in total shoulder arthroplasty

BackgroundShoulder arthroplasty is technically demanding and can be associated with failures due to implant loosening, especially in the presence of posterior glenoid bone loss. Novel preoperative planning has been employed more frequently in an attempt to improve implant positioning, however, there is little data comparing the effectiveness of various systems for shoulder arthroplasty.  Our goal was to assess the reliability and validity of preoperative planning software systems for measurements and implant selection.MethodsA retrospective analysis was done of 80 patients who underwent total shoulder arthroplasty. Preoperative computed tomography studies were used to create a preoperative plan using 3 software systems: independent preoperative plan software (IPPS) and 2 automated manufacturer preoperative simulation (AMPS I and II). We collected preoperative native and implant version and inclination and implant size from each software. Simulated plans of each patient were compared to one another.ResultsThe mean age of our population was 61 years old (±12), 51.3% females and 48.8% males. The mean native version measured by IPPS was −9.1° ± 11.3°, by AMPS I was −11.7° ± 8° and by AMPS II software was −11° ± 13.4° The mean native inclination for IPPS was 4.7° ± 6.8°, for AMPS I was 10.4° ± 5.9° and for AMPS II software was 7.76° ± 7.2° The mean implant version for IPPS was −4.8° ± 6.5°, for AMPS I was −6.73° ± 2.6° and for AMPS II software was −5.4° ± 5° The mean implant inclination suggested by IPPS was 2.04° ± 4.4°, by AMPS I was 3.5° ± 3.2° and by AMPS II software was 7.04° ± 7.2° Five of 14 comparisons resulted in statistically significant differences. Our results demonstrated strong positive correlations (r > 0.7) between AMPS I and AMPS II for Native Version and Implant Inclination. When implant diameter/size was compared between IPPS and AMPS II, AMPS I and AMPS II, we found a matching rate of 66.7% and 100%, respectively.ConclusionOur results support the use of either independent or commercially available preoperative simulation software to reliably measure pathology and accurately guide intraoperative implant selection. Notwithstanding, some manufacturer's software (AMPS II) provide more critical data, enhancing precision in implant placement and correction of pathologic bone loss. Level of evidenceLevel III.     

A paradigm shift in surgical planning and simulation using 3Dgraphy: Experience of first 50 surgeries done using 3D-printed biomodels

IntroductionPreoperative planning is an important aspect of any orthopedic surgery. Traditionally, surgeons mentally rehearse the operation and anticipate problems based on data available from “radiography” like MRI and CT. 3D printed bio-models and tools, or “3Dgraphy” can simplify this mental exercise and provide a realistic and user-friendly portrayal of this radiographic data.MethodsFive surgeons participated in this multicenter study. 3D printed biomodels were obtained for 50 surgical cases that included periarticular trauma (24), pelvic trauma (11), complex primary (7), and revision arthroplasty (8). CT scan data was used to generate computer models which were then 3D printed in real size. These models were used to understand pathoanatomy and conduct simulated surgery as a part of preoperative planning. The models were sterilized and were used for intraoperative referencing. Following each case, the operating surgeon was asked to fill out a structured questionnaire to report on the perceived benefits of these tools.ResultsAll surgeons reported that the biomodels provided additional information to conventional imaging that enhanced their knowledge of the complex pathoanatomy. It was useful in preoperative planning, rehearsing the operation, surgical simulation, intraoperative referencing, surgical navigation, preoperative implant selection, and inventory management. This probably reduced surgical time and improved accuracy of the surgery. All surgeons reported that they would not only use it themselves but also recommend it to other surgeons.Conclusion3Dgraphy was found to be a valuable tool in orthopedic surgeries that involve complex pathoanatomy like pelvic trauma, revision arthroplasty, and periarticular fracture. As the technology evolves and improves, they are likely to become a standard component of many orthopedic procedures.