基于CT和解剖的三维数字化腕关节模型的构建

目的 探讨基于CT影像重建和虚拟解剖复位的三维数字化腕关节模型的构建及其应用价值,为开展腕关节生物力学功能研究准备前处理形态学模型.方法 采集1例中国青年男性志愿者右前臂高分辨CT图像,应用Mimics软件进行三维骨性重建;通过腕关节标本解剖和数值调查,应用3D-Doetor软件在CT图像软组织灰度区域,分割三角纤维软骨盘和韧带群并三维重建;将骨结构、软骨盘和韧带群导入Geomagic软件进行虚拟解剖复位和模型配准,构建网格优化的腕关节数字模型.结果 建立了包括桡、尺骨,掌骨(包含皮质、松质、髓腔),腕骨,三角纤维软骨复合体,桡腕背侧、桡舟、桡舟头、桡月韧带等结构的三维数字化腕关节模型.模型虚拟构建的韧带、软骨盘等的测量值基本在文献报告的数值范围之内.结论 在目前的个人计算机平台上依据CT影像和解剖资料,利用医学图像处理软件和三维重建软件可以准确、快捷地构建腕关节的三维数字模型,为腕部有限元分析及整个虚拟手的构建提供了技术支撑.     

基于CT和解剖的三维数字化腕关节模型的构建

目的 探讨基于CT影像重建和虚拟解剖复位的三维数字化腕关节模型的构建及其应用价值,为开展腕关节生物力学功能研究准备前处理形态学模型.方法 采集1例中国青年男性志愿者右前臂高分辨CT图像,应用Mimics软件进行三维骨性重建;通过腕关节标本解剖和数值调查,应用3D-Doetor软件在CT图像软组织灰度区域,分割三角纤维软骨盘和韧带群并三维重建;将骨结构、软骨盘和韧带群导入Geomagic软件进行虚拟解剖复位和模型配准,构建网格优化的腕关节数字模型.结果 建立了包括桡、尺骨,掌骨(包含皮质、松质、髓腔),腕骨,三角纤维软骨复合体,桡腕背侧、桡舟、桡舟头、桡月韧带等结构的三维数字化腕关节模型.模型虚拟构建的韧带、软骨盘等的测量值基本在文献报告的数值范围之内.结论 在目前的个人计算机平台上依据CT影像和解剖资料,利用医学图像处理软件和三维重建软件可以准确、快捷地构建腕关节的三维数字模型,为腕部有限元分析及整个虚拟手的构建提供了技术支撑.     

3D digital breast cancer models with multimodal fusion algorithms

Breast cancer image fusion consists of registering and visualizing different sets of a patient synchronized torso and radiological images into a 3D model. Breast spatial interpretation and visualization by the treating physician can be augmented with a patient-specific digital breast model that integrates radiological images. But the absence of a ground truth for a good correlation between surface and radiological information has impaired the development of potential clinical applications.A new image acquisition protocol was designed to acquire breast Magnetic Resonance Imaging (MRI) and 3D surface scan data with surface markers on the patient’s breasts and torso. A patient-specific digital breast model integrating the real breast torso and the tumor location was created and validated with a MRI/3D surface scan fusion algorithm in 16 breast cancer patients.This protocol was used to quantify breast shape differences between different modalities, and to measure the target registration error of several variants of the MRI/3D scan fusion algorithm. The fusion of single breasts without the biomechanical model of pose transformation had acceptable registration errors and accurate tumor locations. The performance of the fusion algorithm was not affected by breast volume. Further research and virtual clinical interfaces could lead to fast integration of this fusion technology into clinical practice.     

Image Acquisition: Ultrasound, Computed Tomography, and Magnetic Resonance Imaging

As the transition toward total digital image acquisition continues, radiology is transcending the current standard of two-dimensional (2-D) cross-sectional anatomic imaging to more complex models. Among these are three-dimensional (3-D) anatomic images, constructed either from a synthesis of traditional 2-D data sets, or directly from volumetrically acquired data. However, current trends are moving beyond mere anatomic imaging to include physiological data once mainly obtained via nuclear medicine. Recent magnetic resonance pulse sequences, in addition to Doppler and harmonic ultrasound methods, are providing insight into blood flow, oxygenation, and metabolite concentrations non-invasively. Through image registration techniques, these data (even from differing modalities) are being assembled into 2-D and 3-D "fusion" images that promise to revolutionize diagnosis. Furthermore, with improvements in miniaturization, reliability, speed, built-in intelligence, and ease of use, these new developments are finding their way into use by nonspecialists. For instance, a new hand-held ultrasound unit will likely become a common tool among emergency medical teams, military medical teams, and in NASA's manned space program. Portable computed tomography (CT) scanners are already being used in the operating room. The increasing sophistication of imaging instruments will bring about a complementary increase in ease of use for both scanning and data interpretation, bringing diagnostic imaging and therapeutic capabilities closer to the patient, rather than the converse.     

Inter- and Intra-observer Variability of a Cervical OPLL Classification Using Reconstructed CT Images

Background

The lateral radiograph-based system described by Tsuyama is used widely to classify ossification of the posterior longitudinal ligament (OPLL) of the cervical spine. However, OPLL is a complex 3-dimensional (3-D) lesion, not a simple and uniplanar one, which is often difficult to identify on a lateral radiograph. Furthermore, its reliability among spine surgeons has not been investigated. Given the popularity of a reconstructed computed tomography (CT), this study examined the inter- and intra-observer reliability of lateral radiograph-based OPLL classification using that modality.

Methods

Five spine surgeons independently reviewed the lateral radiograph, axial CT, 2-D (sagittal) and 3-D reconstructed CT images of 108 OPLL patients on 2 separate occasions. Based on these images, the reviewers classified each OPLL case according to the Tsuyama''s system. The kappa values were used to assess the statistical reliability.

Results

The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.

Conclusions

The inter- and intra-observer kappa values were only 0.51 and 0.67 for the lateral radiograph, even in combination with the axial CT images, 0.70 and 0.85 for 2-D CT images, and 0.76 and 0.86 for 3-D CT images, respectively. These kappa values showed a good-to-excellent range for the 2-D and 3-D reconstructed CT images while those of the lateral radiograph indicated a fair range. According to the OPLL types, the inter- and intra-observer reliability was low in the continuous type and high in the circumscribed type on the lateral radiograph. However, the low reliability of the continuous type on lateral radiograph was overcome somewhat using 2-D and 3-D reconstructed CT images.     

Development of three-dimensional imaging of the musculoskeletal system and its diagnostic capability]

Since 1987 we have studied osseous surfaces reconstructed three-dimensionally (3-D) from CT images with the cooperation from Hitachi Medico Co., Ltd. From these studies we have developed the following method for various clinical use. The method of this 3-DCT system could treat rather noisy images scanned with low radiation exposure because of the high contrast ratio (CT number) between bones and soft tissues, in the CT images. In addition, the 3-D calculation treated only the extracted data instead of all the CT images data, and the high speed processor was used in our system. These were effective to reduce the processing time. Furthermore, the system provided a natural stereoscopic view using a mixture shading method. Subsequently, this 3-DCT system was applied to clinical cases to examine its diagnostic capability. These results indicate that the 3-DCT system is useful in evaluating pathological conditions of bones and joints.     

三维激光扫描量化评估面部不对称畸形的初步研究

目的研究三维激光表面扫描结合翻转配准法量化评估面部不对称畸形的临床实用价值。方法对于随机抽取的临床面部不对称畸形患者,利用三维激光扫描技术获取三维影像数据,利用翻转配准法获取期望治疗效果,并对期望值与原始图像做差值比较,绘制等高彩色分布图。结果三维激光扫描提供的三维数据准确、迅捷,预期治疗效果可信度高并易于为受试者本人接受。绘制的等高彩色分布图清晰、直观,并可同时提供临床治疗所需的差值体积、术区表面积等基本量化资料。结论三维激光扫描结合翻转配准法可以快速、有效的评价面部不对称畸形患者的疾患严重程度,能够提供准确、直观的三维量化信息,具有极大的临床应用价值。     

Virtual endoscopy is a useful device for training and preoperative planning of transsphenoidal endoscopic pituitary surgery.

Virtual endoscopy (vE) allows simulated three-dimensional (3-D) visualisation of anatomical structures by computerised reconstruction of radiological images. The aim of this study was to evaluate the feasibility of vE and its potential benefits for endoscopic transsphenoidal pituitary surgery. vE was realised using a commercially available ray-casting software plugin of a picture archiving and communications system (PACS). For this study, the vE system was enhanced with volume segmentation, transparency and cutting tools. The data for vE were derived from high resolution computed tomography (CT) scans of 22 patients with pituitary pathology (20 pituitary adenomas, 2 Rathke's cleft cysts) preoperatively. Anatomic structures were identified on vE images and compared with the intraoperative endoscopic views. The simulated 3-D vE images were found to be comparable to the intraoperative endoscopic anatomy in terms of distortion and angle of view. vE was found to be particularly useful for the preoperative depiction of 1) the nasal anatomy and its variations for choosing the side of the approach, 2) the sphenoid sinus septae and chambers for improved intraoperative orientation, 3) the transparent 3-D simulated visualisation of the pituitary gland, tumour and adjacent anatomic structures in relation to the sphenoid sinus landmarks for planning the opening of the sellar floor. We conclude that vE harbours the potential to become a valuable tool in endoscopic pituitary surgery for training purposes and preoperative planning. Furthermore, vE may add to the safety of interventions in case of anatomic variations.     

Three-dimensional computed tomography and multiplanar reformations in the assessment of pseudarthrosis in posterior lumbar fusion patients

Three-dimensional (3-D) surface reconstructions and multiplanar computed tomography (CT) reformations were obtained in 30 patients with clinically suspected spinal fusion pseudarthrosis. The imaging studies were blind-reviewed and the results were compared with the clinical and surgical findings. Sagittal, planar, and curved coronal two-dimensional (2-D) reformations were more useful in the detection of bony nonunion than were axial CT scans, as the latter required more extensive analysis. Three-dimensional surface "cuts" adequately demonstrated pseudarthrosis in most cases. In some instances, however, segmentation artifacts created artifactual clefts or implied solidity, which contrasted with the interpretation of the 2-D images. Sagittal 3-D cuts were helpful in demonstrating bony central and lateral stenosis. Three-dimensional surface reconstructions demonstrated superficial clefts and outlined the complex anatomy of the spinal fusions, thus facilitating pre- and intraoperative planning. The amount of bone stock available for pseudarthrosis repair at the fusion site and the need for additional harvesting of bone from the iliac crest also could be assessed easily. 3-D CT proved to be useful as an adjunctive imaging method in the evaluation of posterior lumbar fusion patients suspected of pseudarthrosis.     

Facial biometrics of peri-oral changes in Crohn’s disease

Crohn’s disease is a chronic relapsing and remitting inflammatory condition which affects any part of the gastrointestinal tract. In the oro-facial region, patients can present peri-oral swellings which results in severe facial disfigurement. To date, assessing the degree of facial changes and evaluation of treatment outcomes relies on clinical observation and semi-quantitative methods. In this paper, we describe the development of a robust and reproducible measurement strategy using 3-D facial biometrics to objectively quantify the extent and progression of oro-facial Crohn’s disease. Using facial laser scanning, 32 serial images from 13 Crohn’s patients attending the Oral Medicine clinic were acquired during relapse, remission, and post-treatment phases. Utilising theories of coordinate metrology, the facial images were subjected to registration, regions of interest identification, and reproducible repositioning prior to obtaining volume measurements. To quantify the changes in tissue volume, scan images from consecutive appointments were compared to the baseline (first scan image). Reproducibility test was performed to ascertain the degree of uncertainty in volume measurements. 3-D facial biometric imaging is a reliable method to identify and quantify peri-oral swelling in Crohn’s patients. Comparison of facial scan images at different phases of the disease revealed precisely profile and volume changes. The volume measurements were highly reproducible as adjudged from the 1 % standard deviation. 3-D facial biometrics measurements in Crohn’s patients with oro-facial involvement offers a quick, robust, economical and objective approach for guided therapeutic intervention and routine assessment of treatment efficacy on the clinic.     

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目的 研究基于64排螺旋CT扫描数据的三维重建和胰腺可视化仿真手术.方法 采集常见胰腺病变的CT扫描数据.通过自适应区域生长法对CT序列图像进行程序分割和提取,采用自行研发的医学图像处理软件对分割后的图像进行三维重建.再将数据以STL格式导入FreeForm Modeling System中修饰、平滑,利用GHOST SDK软件开发出各种仿真手术器械,然后运用PHANTOM力反馈设备进行各种常见胰腺疾病的可视化仿真手术的研究.结果 利用自适应区域生长法对胰腺和脾脏CT图像进行程序分割速度快、效果好.用自行设计的医学图像处理软件进行三维重建,图像结构清晰,可真实再现胰腺的解剖结构,有如在手术台上直接操作、真实手术的感觉.结论 基于64排螺旋CT扫描数据的三维重建和可视化仿真手术,对胰腺等腹部脏器的个体化手术方案制定、风险评估、临床教学训练等方面都有很高的应用价值.     

Advanced three-dimensional evaluation of acetabular trauma: volumetric image processing

Volumetric image processing is a new approach to generating simulated three-dimensional images from transaxial CT data. The major advantages compared to conventional surface-rendering 3D technique include: preservation of every pixel of CT data for increased accuracy of rendered image; tissue layer translucency allowing appreciation of multiple tissue layers on each image; simulation of real-time rotation in varying axes for optimal appreciation of abnormalities; and a high-speed, high-capacity computer setup which generates high-quality images rapidly, giving the system sufficient flexibility for these complicated functions while remaining user friendly and fast.     

Usefulness of 3-dimensional reconstructed images of renal arteries using rotational digital subtraction angiography

PURPOSE: We assess the feasibility of a 3-dimensional (D) reconstruction technique of rotational digital subtraction angiography (DSA) for visualization of the renal arteries. MATERIALS AND METHODS: We evaluated 28 kidneys in 20 patients. Rotational DSA images were obtained during a deep inspiratory pause after contrast material injection through the renal artery. Acquired data were transferred to an image workstation and reconstructed as 3-D images. Visibility of the main trunk of the renal artery, segmental arteries, interlobar arteries and arcuate arteries was classified as grade 4-excellent, grade 3-good, grade 2-satisfactory and grade 1-poor. The 3-D reconstructed images were compared with conventional 2-D DSA performed just before the rotational DSA. The criteria for evaluation were visibility of the aneurysm neck in 8 cases of aneurysm, delineation of the feeding arteries in 6 cases of renal lesions and visibility of the relationship between renal branches in other cases. RESULTS: Delineation of grades 4 to 1 was 93%, 7%, 0% and 0% for the main renal artery, 66%, 21%, 7% and 6% for segmental arteries, 61%, 11%, 21% and 7% for interlobar arteries, and 36%, 18%, 36% and 10% for arcuate arteries, respectively. The 3-D images had the advantage over 2-D DSA in 75% of cases. In all cases of aneurysm 3-D images were obviously more useful than 2-D DSA. CONCLUSIONS: 3-D images of renal arteries obtained with rotational DSA are considered acceptable for clinical use.     

3-D telestration: a teaching tool for robotic surgery

BACKGROUND: Telestration is an important teaching tool in minimally invasive surgery (MIS). While robotic surgery offers the added benefit of three-dimensional (3-D) visualization, telestration technology does not currently exist for this modality. This project aimed to develop a video algorithm to accurately translate a mentor's two-dimensional (2-D) telestration into a 3-D telestration in the da Vinci visual field. MATERIALS AND METHODS: A prototype 3-D telestration system was constructed to translate 2-D telestration from a mentor station into 3-D graphics for the trainee at the robotic console. This system uses fast image correlation algorithms to allow 2-D images to be placed over the same anatomic location in the two separate video channels of the stereoscopic robotic visualization system. Three subjects of varying surgical backgrounds, blinded to the mode of telestration (2-D vs. 3-D), were tested in the laboratory, using a simulated robotic task. RESULTS: There were few technologic errors (2), only one of which resulted in a task error, in 99 total trials. Only the experienced MIS staff surgeon had a significantly faster task time in 2-D than in 3-D (P < 0.05). The MIS fellow recorded the fastest task times in 2-D and 3-D (P < 0.05). There were nine task errors, six of which were committed by the MIS fellow. The nonsurgeon trainee had the least number of errors but also had the slowest times. CONCLUSIONS: Robotic telestration in 3-D is feasible and does not negatively impact performance in laboratory tasks. We plan to refine the prototype and investigate its use in vivo.     

Sanders classification of calcaneal fractures in CT images with deep learning and differential data augmentation techniques

BackgroundClassification of the type of calcaneal fracture on CT images is essential in driving treatment. However, human-based classification can be challenging due to anatomical complexities and CT image constraints. The use of computer-aided classification system in standard practice is additionally hindered by the availability of training images. The aims of this study is to 1) propose a deep learning network combined with data augmentation technique to classify calcaneal fractures on CT images into the Sanders system, and 2) assess the efficiency of such approach with differential training methods.MethodsIn this study, the Principle component analysis (PCA) network was selected for the deep learning neural network architecture for its superior performance. CT calcaneal images were processed through PCA filters, binary hashing, and a block-wise histogram. The Augmentor pipeline including rotation, distortion, and flips was applied to generate artificial calcaneus fractured images. Two types of training approaches and five data sample sizes were investigated to evaluate the performance of the proposed system with and without data augmentation.ResultsCompared to the original performance, use of augmented images during training improved network performance accuracy by almost twofold in classifying Sanders fracture types for all dataset sizes. A fivefold increase in the number of augmented training images improved network classification accuracy by 35%. The proposed deep CNN model achieved 72% accuracy in classifying CT calcaneal images into the four Sanders categories when trained with sufficient augmented artificial images.ConclusionThe proposed deep-learning algorithm coupled with data augmentation provides a feasible and efficient approach to the use of computer-aided system in assisting physicians in evaluating calcaneal fracture types.     

Computer aided long bone fracture treatment

Intraoperative fluoroscopy is the tool for intraoperative control of long bone fracture reduction and osteosynthesis. Limitations of this technology include: High radiation exposure to the patient and the surgical team, limited field of view, image distortion, limitation to 2-D representations, and cumbersome updating of verification images. Fluoroscopy based navigation systems partially address these limitations by allowing fluoroscopic images to be used for real-time surgical localization and instrument tracking. In a clinical study on computer guidance by virtual fluoroscopy for distal locking, the capability to provide online guidance with significantly reduced fluoroscopy times is demonstrated. Virtual fluoroscopy applied for guidewire placement in a laboratory setup demonstrated the potential of the method to reduce procedure times, and the potential to increase precision of implant placement with decreased fluoroscopy times. By using virtual reality enhancement, starting from multiple registered fluoroscopy images, a virtual 3-D cylinder model for each principal bone fragment is reconstructed. This spatial cylinder model is not only used to supply a 3-D image of the fracture, but also allows effective fragment projection extraction from the fluoroscopic images and further achieves radiation-free updates of in-situ surgical fluoroscopic images through a non-linear interpolation and warping algorithm. After primary image acquisition, the image intensifier was replaced by the virtual reality system. It was shown that all the steps of the procedure, including fracture reduction and LISS osteosynthesis can be performed completely in virtual reality.     

Stereotactic accuracy of a 3-tesla magnetic resonance unit

Recently, magnetic resonance imagers (MRIs) with 3-tesla magnets were approved for clinical use. The spatial accuracy of these high-resolution scanners has yet to be proven. In the present study, a computed tomography (CT)- and MRI-compatible phantom was scanned on a CT, a 1.5-tesla MRI and a 3-tesla MRI scanner. The model was registered to the images using an infrared-based surgical navigation system. The distance between the predicted position of the navigation probe tip and the actual target on the image was measured on the x, y and z axes for 13 points on each image. Error was compared across imaging modalities, peripheral versus central targets and along each axis. We found that 3-tesla MRI scans are accurate as stereotactic data sets.     

Comparison of the safety of three methods of lumbar transpedicular screw fixation

Objective: To choose a proper method of lumbar transpedicular screw fixation at different lumbar levels among the three methods (Roy-Camille's method, Magerl's method and Du's method) in the Chinese population. Methods: Three-dimensional ( 3-D ) images were reconstructed with image data of 42 adult lumbar segments that were scanned by Electron Beam CT. The three methods of lumbar pedicle screw fixation were simulated on the 3-D reconstructed images and the parameters of implanting pedicle screws were measured. Results : There was statistically significant difference at the distance from the entrance point to the pedicle axis between the three methods (P<0.001). The distances measured by Du's method were shortest from L1 to L4, and the distances measured by Magerl's method were shortest at L5 (P<0.05). There was no significant difference from L1 to L2 (P >0.05) but significant difference from L3 to L5 at inserting safe ranges of TSA (transverse section angle) was found between the three methods (P<0.05). From L3 to L4, the inserting safe ranges of TSA measured by Du's and Magerl's methods were significantly larger than that measured by Roy-Camille's method (P<0.05), but there was no significant difference between them (P > 0.05). At L5, the inserting safe ranges of TSA measured by Magerl's method were largest among the three methods (P <0.05). Conclusions: Among the three methods, Du's method is the best choice from L1 to L4 because its distance from the entrance point to the pedicle axis is shortest and the safe range of TSA is largest: Magerl's method can be used from L3 to LS and is the best choice at L5; Roy-Camille's method is applicable at L1 and L2.     

In vivo analysis of carpal kinematics and comparative review of the literature

PURPOSE: Techniques have been developed very recently with which it is possible to quantify accurately in vivo 3-dimensional (3-D) carpal kinematics. The aim of this study was to evaluate the feasibility of our novel 3-D registration technique by comparing our data with data found in the literature. METHOD: The right wrists of 11 healthy volunteers were imaged by spiral computed tomography (CT) during radial-ulnar deviation and 5 of those wrists were imaged also during flexion-extension motion. With a matching technique relative translations and rotations of the carpal bones were traced. We compared our in vivo results with data presented in the literature. RESULTS: We found our in vivo data largely to concur with in vitro data presented in the literature. In vivo studies revealed only larger out-of-plane motions within the proximal carpal row than described in most in vitro studies. In vivo studies also showed larger interindividual variations. CONCLUSIONS: A single functional model of carpal kinematics could not be determined. We expect that in vivo 3-D CT studies on carpal kinematics, especially when applied to dynamic wrist motion, will have future diagnostic applications and provide information on long-term results of surgical interventions.     

Novel 3-D video for quantification of facial movement.

OBJECTIVES: To evaluate a novel 3-D geometry video acquisition system (3-D VAS) for quantifying facial movement. METHODS: Ten normal subjects and four patients with facial paralysis underwent recording of facial movement during three facial expressions. Facial feature points of interest were digitally marked on selected images. The maximum 3-D displacement of the brow and oral commissure and palpebral fissure width were determined. RESULTS: Test-retest reliability using the 3-D VAS in normal subjects was high (Spearman correlation coefficients 0.661-0.830, P < 0.05). The predicted ratio of left to right facial measurements was 1.00 in normal subjects, and measured mean ratios were 1.05 (brow excursion), 1.01 (palpebral fissure width), and 1.03 (oral commissure excursion), respectively, matching the prediction. The 3-D VAS reliably quantified facial movement on both sides in patients with facial paralysis. CONCLUSIONS: The novel 3-D VAS can accurately and reliably quantify facial movement in healthy subjects. It is promising as a clinical tool to quantify facial movement in patients with facial paralysis.