Relative weights of the human carpal bones: biological and functional interests

The relative carpal weights (Weight of each of the eight carpal bones/Weight of the complete carpus × 100) were studied in a series of 95 complete human adult carpi (dried bones). The greatest was the capitatum (19.92%; mean rank 1.16) and the smallest the pisiform (4.43%; mean rank 8.00). The scaphoideum and the hamatum presented very near values (17.19 and 15.81%; mean ranks 2.34 and 2.74), as did the lunatum and trapezium (12.56 and 12.52%; mean ranks 4.41 and 4.48), and the triquetrum and trapezoideum (9.21 and 8.36%; mean ranks 6.19 and 6.68). Within the proximal row, a regular radio-ulnar decrease was observed from the scaphoideum (39.58%) to the pisiform (10.20%). Within the distal row, a marked break existed between the trapezoideum (14.77%) and the capitatum (35.19%); the capitato-hamatal element represented 63.11% of the distal row. The distal row (mean 56.61%) was always a little heavier than the proximal row (mean 43.39%), resulting in a mean proximo-distal weight ratio of 0.77. A radio-ulnar decrease in the relative weights was observed from the radial to the ulnar carpal columns. The determination of the relative carpal weights is simple, reproducible, non-invasive, rapid, and inexpensive, and can be considered an interesting and valuable approach to the estimation of the relative carpal volumes. Relative carpal weights reveal the intrinsic proportions of the carpus and are the reflection of biological, functional and evolutionary constraints. Interesting relations appear with carpal growth and ossification, with functional characteristics, and with evolutionary processes.     

超声三维成像综述

本文对超声三维成像的发展及国内外的研究现状进行了综述，简单介绍了超声三维成像的理论和方法，另外，将超声三维成像在临床中的应用做了较为广泛的概括，最后，文中讨论了影响三维重建效果的因素，并提出了一些值得关注的研究方向。     

影像纠正在下颌骨CT切片三维重建中的应用

将切片图像准确地对齐 ,是连续切片三维重建的重要步骤 ,它直接影响着重建结果和参数计算的准确性 ,目前这个问题还没有很好的解决方法。本文以下颌骨 CT切片图像三维重建为例 ,在硬定位的基础上提出了基于仿射变换和广义霍夫变换的软定位方法 ,利用控制点 ,来进行定位处理 ,取得了较好的效果。实验结果表明 ,该方法定位精度高 ,重建图像失真度很小     

DLT算法中象平面误差对三维重构的影响

ＤＬＴ算法是利用平面图象进行三维重构的广泛采用的基本算法。本文针对平面图象处理中难以避免的象坐标误差,讨论了各坐标误差对三维重构坐标的影响,由此分析了三维重构坐标对各象坐标误差的敏感程度,并进行了数值模拟实验。     

In vitro 3D reconstruction of long bones using B-scan image processing

An echographic image processing method has been developed, and validated by in vitro experiments, for the 3D reconstruction of the long bones of the newborn. The reconstruction of successive parallel cross-sections is obtained by a 2D reconstruction technique using radial B-scan image processing. The automatic segmentation of all the calculated images allows the extraction of the external contours of the skeleton. After structuring the explored volume using a contour association method, a contour interpolation step is required to solve the anisotropy problem, to obtain a 3D representation with cubic voxel lists. The results are encouraging, and a new mechanical part prototype of the acquisition system is under test for in vivo experiments. The main originality of the paper lies in the combination of different steps to obtain a practical solution to a clinical problem.     

Three-dimensional motion patterns of the carpal bones: an in vivo study using three-dimensional computed tomography and clinical applications

A three-dimensional (3D) CT technique was developed to analyze in vivo segmental carpal kinematics. Transverse CT data of the distal forearm, carpals and proximal metacarpals was acquired and 3D reconstructed in various wrist positions. Carpal kinematics were analyzed in two groups of 20 asymptomatic volunteers, one group in neutral position, flexion and extension (45°), and the other group in neutral position, radial (15°) and ulnar deviation (30°). Qualitative analysis included the 3D study of carpal anatomy, and comparison of carpal bone position between the different sets of data obtained. Carpal bone motion was quantified using rigid body and finite helical axis concepts. The results, although agreeing in principle with previous findings, showed important individual variations in carpal bone motion. Clinical applications were conducted in a series of 25 patients with various wrist disorders. There was no significant difference between the injured wrist and the heterolateral, asymptomatic wrist, but there was a significant difference between asymptomatic volunteers and both the injured wrist and heterolateral wrist of patients. In particular, scaphoid motion was altered bilaterally in our patient group, suggesting the existence of anatomic and/or kinematic factors predisposing to certain carpal pathologies. This hypothesis needs to be confirmed and refined.     

Volumetric analysis of CT orbital images

The determination of the volume of eye muscles is a problem of considerable interest in Graves' ophtalmopathy both with respect to the diagnostic quantisation of the disease and to the measured assessment of the effectiveness of pharmacological treatment. The aim of this research is to design and test an advanced method for processing computerised tomography (CT) orbital images in order to obtain a three-dimensional reconstruction of infra-orbital muscle structures and to analyse them from a morphometric viewpoint. CT images of subjects suffering from Graves' disease were acquired before and after pharmacological treatment with immunosuppressors. They were then processed along with CT images of an anatomical phantom of known volume and fusiform morphology in order to assess the reliability of the procedure and to calculate the effect of the different modalities of acquisition and processing of CT images on the error in volume calculation.     

基于CT图像的股骨上段有限元建模及单元尺寸分析

目的基于CT图像构建5个不同的股骨上段有限元模型,并分析模型单元尺寸对股骨模型材料属性分布以及生物力学性能的影响。方法利用螺旋CT扫描股骨上段并以DICOM格式输出图像文件,利用Mimics软件提取三维几何文件,分别使用Mimics、3-Matica、ICEM软件生成体素网格模型、四面体网格模型和3个六面体网格模型(单元尺寸分别为2、1和0.5 mm),在Mimics中对网格文件进行材料赋值,将最终的有限元模型导入ABAQUS中进行力学行为分析。结果单元尺寸对5个模型总质量影响较小,5个模型沿相同路径上节点处Von Mises应力和节点位移整体变化趋势一致,但是各个节点处Von Mises应力误差较大,单元尺寸为0.5 mm的六面体网格模型与体素网格模型各节点处Von Mises应力值接近。结论基于CT灰度值进行材料赋值时,单元尺寸对模型的总质量和节点位移影响较小,但是单元尺寸的减小将导致模型中各材料含量和分布的改变,引起应力分布的变化。当模型单元尺寸与体素尺寸接近时,能较好反映股骨的质量分布和力学行为。     

基于CT影像的人体心脏三维重构

三维重构是研究心脏血流机理及特性等问题的有效手段,本文基于CT断层扫描数据,利用Mimics处理工具对心脏进行三维重构,并对左心室优化模型进行偏差分析,优化改变了重构模型的粗糙度,对左心室结构的影响较小为后续探究心脏内部血流模式及特性、血液生理学参数异变和组织结构病变提供了基础研究。     

Factors Affecting Dimensional Accuracy of 3-D Printed Anatomical Structures Derived from CT Data

Additive manufacturing and bio-printing, with the potential for direct fabrication of complex patient-specific anatomies derived from medical scan data, are having an ever-increasing impact on the practice of medicine. Anatomic structures are typically derived from CT or MRI scans, and there are multiple steps in the model derivation process that influence the geometric accuracy of the printed constructs. In this work, we compare the dimensional accuracy of 3-D printed constructs of an L1 vertebra derived from CT data for an ex vivo cadaver T-L spine with the original vertebra. Processing of segmented structures using binary median filters and various surface extraction algorithms is evaluated for the effect on model dimensions. We investigate the effects of changing CT reconstruction kernels by scanning simple geometric objects and measuring the impact on the derived model dimensions. We also investigate if there are significant differences between physical and virtual model measurements. The 3-D models were printed using a commercial 3-D printer, the Replicator 2 (MakerBot, Brooklyn, NY) using polylactic acid (PLA) filament. We found that changing parameters during the scan reconstruction, segmentation, filtering, and surface extraction steps will have an effect on the dimensions of the final model. These effects need to be quantified for specific situations that rely on the accuracy of 3-D printed models used in medicine or tissue engineering applications.     

Morphometry by computerized three-dimensional reconstruction of the human carpal bones during embryogenesis

Carpal skeleton shows drastic developmental changes during embryogenesis. At this stage, the cartilaginous matrices appear and later form models of the limb bones. The purpose of this study was to investigate the morphometry of carpal bones in humans during embryological development. We obtained digitalized histological serial sections of 18 human embryos and early fetuses from the Institute of Anatomy in Paris. Surfdriver and MSC.Patran software were used for three-dimensional reconstruction and morphometry. There was a strong correlation between the volume of the carpal cartilaginous structure and the size of the embryos (P<0.001) and an exponential correlation between the carpal volume and the percentage of volume presented by the proximal carpal row (P=0.005). According to inertia parameters, the geometry of carpal cartilaginous structure, initially plane, becomes curved during embryogenesis. Carpal bones growth follows non-homothetic transformation. The innovations in embryo reconstruction serve as new tool for scientific investigation. A hypothesis of carpal development is proposed.     

骨科医学断层图像的三维重构应用及其纹理特征研究

目的在已有的骨科多源信息综合管理及特征分析系统基础上,设计开发嵌入式的、可辅助临床的医学断层图像三维可视化模块,研究医学断层图像重构后任意剖切面纹理特征的应用意义。方法在Visual Studio 6.0开发平台上开发图像三维重构模块;利用数字特征提取功能模块分别提取断层图像重构前和重构后的纹理信息,进行统计学分析。结果三维重构模块扩展原有数字特征提取模块的应用范围,可有效辅助临床医生观察疾病病灶三维体位,可对三维重构图像的任意切面进行数字化特征提取和研究。结论经实验研究验证重构图像新剖面的纹理特征有效保留断层图像纹理特征,可用于疾病辅助诊断的研究。     

Quantitative in vivo analysis of the kinematics of carpal bones from three-dimensional CT images using a deformable surface model and a three-dimensional matching technique

The purpose of this study was to obtain quantitative information of the relative displacements and rotations of the carpal bones during movement of the wrist. Axial helical CT scans were made of the wrists of 11 volunteers. The wrists were imaged in the neutral position with a conventional CT technique, and in 15-20 other postures (flexion-extension, radial-ulnar deviation) with a low-dose technique. A segmentation of the carpal bones was obtained by applying a deformable surface model to the regular-dose scan. Next, each carpal bone, the radius, and ulna in this scan was registered with the corresponding bone in each low-dose scan using a three-dimensional matching technique. A detailed definition of the surfaces of the carpal bones was obtained from the regular-dose scans. The low-dose scans provided sufficient information to obtain an accurate match of each carpal bone with its counterpart in the regular-dose scan. Accurate estimates of the relative positions and orientations of the carpal bones during flexion and deviation were obtained. This quantification will be especially useful when monitoring changes in kinematics before and after operative interventions, like mini-arthrodeses. This technique can also be applied in the quantification of the movement of other bones in the body (e.g., ankle and cortical spine).     

Three-dimensional hip morphology analysis using CT transverse sections to automate diagnoses and surgery managements

This paper describes an image analysis method that evaluates bone morphology of hip structures including the femur stem, trochanter, neck and head, acetabulum, and pelvis to automate hip diagnoses and surgical managements. On every CT transverse section, radial B-spline curves are used to approximate the ellipse-like acetabulum and femur head and stem. The femur neck is approximated as trapezoid-like and the pelvis horizontally symmetrical structure. The centers of the ellipse-like structures from transverse sections are used to determine 3D axes of the femur stem, head, and acetabulum. The centerlines of the neck or the pelvis on the sections are used to determine the neck axis or pelvis centerplane. Boundary changes of these structures are recognized as concave, convex and hole features that are then identified as fractures, tumors, and spurs. Based on the geometric evaluations of these structures and features, hip surgeries including tumor dissect and bone graft, open reduction using plates, screws and nails, and arthroplasty are automatically managed to achieve the normal hip function including dissection of tumors and reduction of dislocations and angular deviations between the hip structures. This prototype system can be used as a qualitative and quantitative tool for the diagnosis of various hip diseases and for the planning of accurate surgical procedures. A series of examples and four case studies illustrate this automated method can be used to accurately diagnose hip diseases and manage hip surgeries, and train operators.     

Quantitative MRI analysis of anatomic dimensions of the carpal tunnel in women

Summary 114 wrists from two groups of asymptomatic women of 25–45 years of age (group I, no=30) and over 45 years (group II, no=27) were examined: a) to quantify the anatomic features of the carpal tunnel, and b) to search for age-related changes in the anatomy of the tunnel. Bilateral MRI axial wrist images were obtained by means of turbo spin echo (TSE) and fast field echo (FFE) sequences. We measured the length, the cross-sectional areas, the volume of the carpal tunnels — from inlet to outlet — and the volume of the wrists, bilaterally. A carpal tunnel volume/wrist volume (CTV/WV) ratio was obtained in both groups. We also searched for the location of the narrowest point of the canal. The mean (SD) length of the tunnel, from inlet to outlet, was 36.3 mm (SD=3.4), in both groups. The tunnel had a cone shape, with the inlet constantly larger than the outlet in all subjects. The mean (SD) cross-sectional area of the tunnel inlet was found to be larger in group II, compared to group I (p=0.029). The calculated mean (SD) volume of the tunnel also appeared significantly larger in the older group (p=0.023). The narrowest point of the canal was identified at its distal third, at 8 mm from the outlet, in both groups. We conclude that: a) quantitative MRI is a valuable method for assessing the anatomic characteristics of the carpal tunnel, and b) the anatomy of the tunnel is affected by age.

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Analyse quantitative IRM des dimensions du tunnel carpien chez la femme

Résumé 114 poignets provenants de deux groupes de femmes asymptomatiques de 25 à 45 ans (groupe I, n=30) et de plus de 45 (groupe II, n=27) ont été examinés. Les caractéristiques anatomiques du canal carpien ont été quantifiées tandis que des modifications de ce canal liées à l'âge ont été recherchées. Les images IRM des deux poignets ont été obtenues en spin-écho et en écho rapide. Ont été mesurées la longueur et la surface de section ainsi que le volume des tunnels carpiens de son entrée jusqu'à sa sortie ainsi que le volume des deux poignets. Un ratio volume du tunnel par rapport au volume du poignet a été obtenu dans les deux groupes. Le point le plus étroit du tunnel carpien a également été localisé. La longueur moyenne du tunnel était de 36,3 mm dans les deux groupes. Le tunnel a la forme d'un cône, avec une entrée constamment plus large que la sortie. La surface de section moyenne du tunnel à son entrée a été trouvée plus importante dans les deux groupes. Le volume moyen du tunnel apparaît significativement plus grand chez les patients âgés. Le point le plus étroit du tunnel a été localisé au tiers distal à 8 mm de la sortie du canal et dans les deux groupes. Nous en concluons : — Que l'analyse IRM quantitative est une méthode valable pour mesurer les caractéristiques anatomiques du tunnel carpien. — Que l'anatomie du tunnel carpien est affectée par l'âge.

     

三维坐标下任意方向的投影变换及反投影重建方法

提出一种三维坐标下任意方向的投影变换及反投影重建的方法,并且给出一个基于多个二维投影变换及反投影重建的简单实现方式,计算机仿真实验的结果证明了该方法的可行性.本文提出的三维投影变换及反投影重建,不仅可以应用在放疗计划的设计过程中,也可用在多层CT的成像过程、数字减影等多种三维图像重建中.     

MSCT图像后处理在显示翼腭窝结构中的价值

目的　探讨多层螺旋CT的各向同性扫描对于翼腭窝结构及其相关通道的完整显示,多平面重组(MPR)步骤,及其临床应用价值。 方法　运用Siemens 16 CT扫描仪行鼻窦螺旋CT检查,选取　100名无翼腭窝及其通道病变的成人,由工作站进行容积显示(VR)、最大密度投影(MIP)及多平面重组　(MPR),观察翼腭窝结构及其通道的形态、走行。 结果　圆孔、翼管、蝶腭孔、翼腭管、腭鞘管、犁鞘管在其最佳辨认方位上显示率分别为99%、98%、99%、96%、96%、85%。　结论　多层螺旋CT能多方位而且直观地显示翼腭窝骨性结构及其通道,能为早期发现相关病变及为制订临床治疗方案提供影像学依据。     

髋臼几何参数的CT测量

背景：近年来尽管对髋臼形态特征的研究已经取得了一些成果,但由于髋臼结构和位置的特殊性,有关髋臼表面形态的定量描述至今尚未统一,这势必会影响髋关节病变诊断和治疗的准确性。 目的：探讨髋臼几何参数的CT测量方法。 方法：选取70例髋关节CT受检者,其中正常成人50例(两侧共100个髋关节),单侧先天性髋关节脱位患儿20例。对所有受检者髋关节CT图像进行冠状面重建和三维重建,比较正常成人髋臼上外倾角冠状位和三维测值,比较先天性髋关节脱位组患侧与正常侧髋臼上外倾角。选择配伍组设计方差分析,分别比较扫描床面为参照面和以身体冠状面为参照面测量左右侧髋臼后外展角、前髋臼指数及后髋臼指数。 结果与结论：髋臼上外倾角在冠状位测值为(39.99±6.1)°,在三维图像上测值为(40.13±5.80)°,2者比较,差异无显著性意义(P > 0.05)。先天性髋关节脱位患儿双侧上外倾角在冠状面的测量值,正常侧为(48.95±3.80)°,脱位侧为(63.56±6.35)°,二者之间差异有非常显著性意义(P < 0.01)。以扫描床面为参照面测量正常髋臼后倾角、前髋臼指数、后髋臼指数左右侧比较,差异有非常显著性意义(P < 0.01);以身体冠状面为参照面测量髋臼后倾角、前髋臼指数、后髋臼指数左右侧比较,差异无显著性意义(P > 0.05)。提示以冠状面为参照平面测量双侧后外展角和前、后髋臼指数准确可靠,可客观反映髋臼情况,为髋关节区病变的诊断和治疗提供确切的量化指标。     

全髋置换术中臼杯置放角度对关节屈伸活动安全性的影响

目的:通过髋臼及臼杯的三维重建及基于此的解剖形态研究,就临床上臼杯假体安装角度对术后髋关节活动安全性改变作一定量分析。方法:通过CT扫描,图像边界处理和定标,利用三维运行软件拟合出髋臼及臼杯三维结构,利用MPR技术重建出髋臼水平及冠状切面,测算出臼杯前倾及外展角,并构建髋关节活动过程中,角度动态变化曲线。结果:骨盆由生理位向前倾斜,随着前倾的增加,臼杯外展角呈增加趋势;臼杯初始置入前倾角较大或外展角较小者,骨盆倾斜角度的变化所引起臼杯前倾角变化的幅度较大。骨盆由生理位向前倾斜,随着骨盆前倾状态的增加,臼杯前倾角呈减少趋势;臼杯初始置入的外展角越大,骨盆倾斜角度的变化所引起臼杯外展角变化的幅度越大。较大的初次臼杯置入前倾角,能减缓骨盆前倾状态增加所致臼杯前倾角减少的幅度。结论:臼杯前倾角及外展角间互相制约,在安全角度范围内作臼杯置入可取得髋臼杯对股骨头良好包容及生理安全活动度间的最佳匹配。