A Computer-Assisted System for Diagnostic Workstations: Automated Bone Labeling for CT Images

Although accurate information on thoracolumbar bone structure is essential when computed tomography (CT) images are examined, there is no automated method of labeling all the vertebrae and ribs on a CT scan. We are developing a computer-aided diagnosis system that labels ribs and thoracolumbar vertebrae automatically and have evaluated its accuracy. A candidate bone was extracted from the CT image volume data by pixel thresholding and connectivity analysis. All non-bony anatomical structures were removed using a linear discriminate of distribution of CT values and anatomical characteristics. The vertebrae were separated from the ribs on the basis of their distances from the centers of the vertebral bodies. Finally, the thoracic cage and lumbar vertebrae were extracted, and each vertebra was labeled with its own anatomical number by histogram analysis along the craniocaudal midline. The ribs were labeled in a similar manner, based on location data. Twenty-three cases were used for accuracy comparison between our method and the radiologist’s. The automated labeling of the thoracolumbar vertebrae was concordant with the judgments of the radiologist in all cases, and all but the first and second ribs were labeled correctly. These two ribs were frequently misidentified, presumably because of pericostal anatomical clutter or high densities of contrast material in the injected veins. We are confident that this system can contribute usefully as part of a picture archiving and communication system workstation, though further technical improvement is required for identification of the upper ribs.     

Automatic Estimation of Orientation and Position of Spine in Digitized X-rays using Mathematical Morphology

In this paper, we propose a method for automatic determination of position and orientation of spine in digitized spine X-rays using mathematical morphology. As the X-ray images are usually highly smeared, vertebrae segmentation is a complex process. The image is first coarsely segmented to obtain the location and orientation information of the spine. The state-of-the-art technique is based on the deformation model of a template, and as the vertebrae shape usually shows variation from case to case, accurate representation using a template is a difficult process. The proposed method makes use of the vertebrae morphometry and gray-scale profile of the spine. The top-hat transformation-based method is proposed to enhance the ridge points in the posterior boundary of the spine. For cases containing external objects such as ornaments, H-Maxima transform is used for segmentation and removal of these objects. The Radon transform is then used to estimate the location and orientation of the line joining the ridge point clusters appearing on the boundary of the vertebra body. The method was validated for 100 cervical spine X-ray images, and in all cases, the error in orientation was within the accepted tolerable limit of 15°. The average error was found to be 4.6°. A point on the posterior boundary was located with an accuracy of ±5.2 mm. The accurate information about location and orientation of thespine is necessary for fine-grained segmentation of the vertebrae using techniques such as active shape modeling. Accurate vertebrae segmentation is needed in successful feature extraction for applications such as content-based image retrieval of biomedical images.     

健康国人颈椎和腰椎体积骨密度的定量CT研究

目的 探讨国人健康成人颈椎和腰椎体积骨密度值(vBMD)分布情况。方法 采用横断面研究方法。2014年12月—2016年1月北京积水潭医院招募770名健康志愿者,其中男329名,女441名,年龄21～59岁。志愿者按年龄分为4组:A组(21～30岁)142人,B组(31～40岁)262人,C组(41～50岁)263人,D组(51～60岁)103人。采用日本TOSHIBA 128排CT机对志愿者行颈椎和腰椎定量CT扫描,并使用Mindways骨密度测量软件测量C₂～C₇、L₂～L₄椎体的vBMD值。采用单因素方差分析分别比较颈、腰椎中vBMD在不同性别、年龄组、节段的分布情况,男性、女性颈腰椎间各椎体vBMD的相关性采用Pearson相关分析。结果 男性志愿者C₂～C₇和L₂～L₄椎体vBMD分别为(288.40±60.63)、(275.71±56.33)、(283.91±59.62)、(278.95±53.76)、(253.38±49.99)、(217.94±44.96)和(151.64±31.74)、(145.22±31.77)、(147.16±35.81)mg/cm³,女性志愿者分别为(329.24±74.34)、(313.88±67.86)、(328.54±73.40)、(323.22±72.53)、(286.44±66.36)、(251.53±58.63)和(168.50±37.10)、(160.78±37.00)、(162.81±37.10)mg/cm³。无论男性还是女性,颈椎及腰椎的体积骨密度值均随着年龄增长而逐渐下降,差异均有统计学意义(P值均＜0.05)。男性志愿者同一年龄组内比较:C₂～C₇不同椎体的vBMD均呈下降趋势,差异均有统计学意义(P值均＜0.05);而L₂～L₄不同椎体的vBMD差异均无统计学意义(P值均＞0.05)。女性志愿者同一年龄组内比较:C₂～C₇不同椎体的vBMD均呈下降趋势,差异均有统计学意义(P值均＜0.05);D组L₂～L₄各椎体的vBMD均呈下降趋势,差异有统计学意义(P＜0.05),其他年龄组vBMD差异均无统计学意义(P值均＞0.05)。无论是男性或女性志愿者,在任何年龄组,颈椎vBMD均＞200 mg/cm³,腰椎vBMD值均＜200 mg/cm³,颈椎vBMD值均高于腰椎(P值均＜0.01)。男性、女性颈腰椎不同椎体间vBMD值均具有显著的相关性(r_男性=0.509～0.968, r_女性=0.658～0.976, P值均＜0.01);男性中,r_颈椎间=0.667～0.928,r_腰椎间=0.850～0.968,r_{颈椎与腰椎间}=0.509～0.675;女性中,r_颈椎间=0.754～0.933,r_腰椎间=0.956～0.973,r_{颈椎与腰椎间}=0.658～0.752;颈椎间或腰椎间vBMD相关系数均高于颈腰椎之间相关系数。结论 颈椎和腰椎vBMD在不同性别、年龄、节段分布存在差异,但各椎体vBMD均存在中-强相关性。本研究结果可为临床监测骨质疏松、评估骨折风险提供参考数据。     

正常腰椎表观弥散系数值大小及其变化规律

目的探讨正常腰椎表观弥散系数(ADC)值的大小及其腰椎1～5椎体ADC值大小的变化关系,以及腰椎ADC值随年龄变化规律。方法125例正常志愿者,其中男性78例,女性47例;年龄12～68岁,平均年龄43.21岁(标准差11.75岁)。其中≤20岁26例,男性17例,女性9例;20～40岁61例,男性37例,女性24例;>40岁38例,男性26例,女性12例。回顾分析其临床及MRI显示正常的腰椎病例,感兴趣区(ROI)大小分别取33、66、132、165、198、231、264、297mm2,分别测量并计算腰椎1～5椎体的ADC均值及腰椎总均值,按年龄分组分成≤20岁、20～40岁及>40岁3组,计算3组ADC均值,并作统计分析。结果腰椎ADC(×10-4mm2/s)总均值为1.92±0.79;腰椎1～5椎体的ADC(×10-4mm2/s)值分别为2.00±0.76、1.88±0.71、1.87±0.87、1.88±0.83及1.99±0.75。经t检验显示,腰椎1、5椎体间差异无统计学意义,腰椎2、3、4椎体间差异无统计学意义(P>0.05),腰椎1、腰椎5与腰椎2、3、4椎体间差异有统计学意义(P<0.05)。腰椎1～3椎体的ADC值呈逐渐变小趋势,腰椎1与腰椎5椎体的ADC值接近。≤20岁、20～40岁及>40岁3组的ADC(×10-4mm2/s)值分别为1.94±0.77、1.93±0.82、1.89±0.79,3组间差异无统计学意义(P>0.05)。结论腰椎的ADC(×10-4mm2/s)总均值约为1.92±0.79,存在两头大中间小的变化趋势,测量病变腰椎的ADC值时,应选取与其正常情况下ADC值最接近的正常椎体作为对照较为适宜;随年龄增长,腰椎ADC值有下降的趋势。     

Radiographic and Magnetic Resonance Imaging Identification of Thoracolumbar Spine Variants with Implications for the Positioning of the Conus Medullaris in Rhesus Macaques

The anatomy of the vertebral column in mammals may differ between species and between subjects of the same species, especially with regards to the composition of the thoracolumbar spine. We investigated, using several noninvasive imaging techniques, the thoracolumbar spine of a total of 44 adult rhesus macaques of both genders. Radiographic examination of the vertebral column showed a predominant spine phenotype with 12 rib‐bearing thoracic vertebrae and 7 lumbar vertebrae without ribs in 82% of subjects, whereas a subset of subjects demonstrated 13 rib‐bearing thoracic vertebrae and 6 lumbar vertebrae without ribs. Computer tomography studies of the thoraco‐lumbar spine in two cases with a pair of supernumerary ribs showed facet joints between the most caudal pair of ribs and the associated vertebra, supporting a thoracic phenotype. Magnetic resonance imaging (MRI) studies were used to determine the relationship between the lumbosacral spinal cord and the vertebral column. The length of the conus medullaris portion of the spinal cord was 1.5 ± 0.3 vertebral units, and its rostral and caudal positions in the spinal canal were at 2.0 ± 0.3 and 3.6 ± 0.4 vertebral units below the thoracolumbar junction, respectively (n = 44). The presence of a set of supernumerary ribs did not affect the length or craniocaudal position of the conus medullaris, and subjects with13 rib‐bearing vertebrae may from a functional or spine surgical perspective be considered as exhibiting12 thoracic vertebrae and an L1 vertebra with ribs. Anat Rec, 300:300–308, 2017. © 2016 Wiley Periodicals, Inc.     

基于CT数据构建人体腰骶椎的有限元模型

背景：目前有限元模型的方法主要是基于医学图像的建模方法,可直接反映人体腰椎真实的几何形态。 目的：以CT影像数据为基础,利用图像处理软件建立L1~S5节段的腰骶椎三维有限元模型。 方法：选取1名男性健康志愿者,采用各向同性分辨率 0.625 mm 薄层CT扫描数据,以Dicom 格式导入 Mimics 10.0软件,三维化处理后获得腰骶段三维几何面网格模型,通过Geomagic studio 12.0软件曲面化、HyperMesh 10.0软件网格划分,最终导入Abaqus10.1软件生成腰骶椎三维有限元模型。 结果与结论：建立了精确的人体腰骶椎三维有限元模型并验证有效。应用精细的影像学数据,通过软件进行图像处理,快捷有效完成了脊柱模型的构建。此完整的多节段模型可方便考察临床疾病和外科固定对脊柱整体的影响,弥补了目前单个运动节段模型的缺陷。     

Spondylocarpotarsal synostosis syndrome and cervical instability

Spondylocarpotarsal synostosis syndrome is a recently delineated autosomal recessive condition comprising short stature with short trunk, failure of normal spine segmentation resulting in block vertebrae and fusion of posterior elements, carpal and/or tarsal coalition, scoliosis, lordosis, pes planus, dental enamel hypoplasia, decreased range of motion or dislocation of the elbow, renal anomalies, and hearing loss. The vertebral segmentation defects may involve noncontiguous areas of the cervical, thoracic, and lumbar spine. Odontoid hypoplasia was noted in two cases. We report on a sporadic case of spondylocarpotarsal synostosis in a 5-year-old girl with hypoplasia of C1 and odontoid and subluxation of C2 upon C3. This brings the number of well-documented cases of spondylocar- potarsal synostosis to 19, and is the first documenting cervical spine instability. Careful evaluation for this complication should be considered in other cases.     

Coexisting Spine Lesions on Whole Spine T2 Sagittal MRI in Evaluating Spinal Degenerative Disease

BackgroundStudies have reported on the usefulness of whole spine magnetic resonance imaging (MRI) in evaluating specific diseases such as spinal tuberculosis, spinal trauma, spondyloarthropathies, and multiple myeloma. In studies concerning degenerative spinal disease, sample sizes were small and some did not provide information on how symptomatic coexisting lesions were treated. We evaluated the types and prevalence of coexisting spine lesions found on whole spine T2 sagittal screening performed at the time of routine cervical and lumbar spine MRI and evaluated the efficacy of such screening in degenerative diseases of the cervical and lumbar spine.MethodsWe reviewed 1,757 and 2,266 consecutive cases where whole spine T2 sagittal screening had been performed with routine cervical and lumbar spine MRI, respectively, in patients with cervical and lumbar spinal degenerative diseases. Coexisting spine lesions were documented and statistical analysis was performed to investigate significant differences according to sex, age, and initial diagnosis. Electronic medical records were reviewed to determine whether additional interventions were necessary following such findings.ResultsWe reviewed 1,252 and 1,689 consecutive cases of routine cervical and lumbar spine MRI respectively, with whole spine T2 sagittal screening. Of the 1,252, 419 (33.5%) patients with cervical spinal degenerative disease had coexisting lesions in the thoracolumbar spine. Patients with ligament ossification disease of the cervical spine showed a higher prevalence of coexisting spine lesions. Sixty of the 419 (14.3%) patients with coexisting spine lesions warranted additional intervention or surgical treatment. Four hundred and eighty-one of 1,689 (28.5%) patients with lumbar degenerative disease had coexisting spine lesions in the cervicothoracic spine. Forty-eight of the 481 (10.0%) patients with coexisting spine lesions warranted additional intervention. In both patient groups, older patients showed a significantly higher prevalence of coexisting spine lesions than younger patients.ConclusionConsidering the minimal extra time and cost in performing whole spine screening, its application to routine spine MRI can be considered in evaluating cervical and lumbar spinal degenerative diseases.     

三线影在腰椎X线影像解剖中的意义

目的 :研究腰椎椎体三线影的X线影像解剖基础。方法 :通过对 60套椎骨标本外形和X线影像的对比观察 ,探讨三线影的成像机理。分析 2 0 0例腰椎正侧位X线片 ,3 5例双斜位片 ,观测三线影的显示情况。结果 :椎体上、下面的X线影像可表现为单线影、双线影和三线影 ,三线影是基本表现。 2 0 0例X线片 ,正位有 197例 (98.5 % ) ,至少一个椎体终板存在三线影 ,共计 882个 ,侧位片则均可见三线影 ,共计14 2 2个椎体终板。结论 :椎体终板的三线影成像规律对腰椎X线影像诊断有重要价值。     

平行光三维运动测量系统的研制及其在人体完整腰椎上的应用

为了进行人体完整腰椎的运动学研究，设计和制造平行光三维运动测量和分析系统。改进加载装置，以减少实验设备对腰椎运动的干扰。随着载荷的改变，人体新鲜腰椎标本产生不同的运动。通过测量系统，设立在每个椎体上的三个标志点的运动分别投影到光屏，摄像机动态记录，输入计算机图像处理系统。利用刚体运动的原理进行计算，获得各标志点的三维运动量的完整腰椎的运动学特点。     

Progressive vertebral fusion of unknown etiology: a case report

We report a 16-year-old male with progressive vertebral fusion of the cervical, thoracic, and lumbar vertebrae; irregular vertebral body surfaces; coronal clefting of the vertebral bodies of the thoracic and lumbar spine; absence of one cervical vertebra; and a few other minor, nonspinous abnormalities. All laboratory findings have been within normal limits. To our knowledge, the particular findings in this patient have not been reported previously.     

Arterial spin labeling MR image denoising and reconstruction using unsupervised deep learning

Arterial spin labeling (ASL) imaging is a powerful magnetic resonance imaging technique that allows to quantitatively measure blood perfusion non-invasively, which has great potential for assessing tissue viability in various clinical settings. However, the clinical applications of ASL are currently limited by its low signal-to-noise ratio (SNR), limited spatial resolution, and long imaging time. In this work, we propose an unsupervised deep learning-based image denoising and reconstruction framework to improve the SNR and accelerate the imaging speed of high resolution ASL imaging. The unique feature of the proposed framework is that it does not require any prior training pairs but only the subject's own anatomical prior, such as T1-weighted images, as network input. The neural network was trained from scratch in the denoising or reconstruction process, with noisy images or sparely sampled k-space data as training labels. Performance of the proposed method was evaluated using in vivo experiment data obtained from 3 healthy subjects on a 3T MR scanner, using ASL images acquired with 44-min acquisition time as the ground truth. Both qualitative and quantitative analyses demonstrate the superior performance of the proposed txtc framework over the reference methods. In summary, our proposed unsupervised deep learning-based denoising and reconstruction framework can improve the image quality and accelerate the imaging speed of ASL imaging.     

The Significance of Calcified Fibrocartilage on the Cortical Endplate of the Translational Sheep Spine Model

To gain an understanding of the vertebral cortical endplate and factors that may affect the ability to achieve skeletal attachment to intervertebral implants and fusion, this study aimed to characterize the hypermineralized tissue on the cortical endplate of the vertebral body on a commonly used animal model. Skeletally mature sheep were injected with tetracycline prior to euthanasia and the C2‐C3, T5‐T6, and L2‐L3 spinal motion segments were excised and prepared. Vertebral tissues were imaged using backscatter electron (BSE) imaging, histology, and tetracycline labeling was used to assess bone remodeling within different tissue layers. It was determined that the hypermineralized tissue layer was calcified fibrocartilage (CFC). No tetracycline labels were identified in the CFC layer, in contrast to single and double labels that were present in the underlying bone, indicating the CFC present on the cortical endplate was not being actively remodeled. The average thickness of the CFC layer was 146.3 ± 70.53 µm in the cervical region, 98.2 ± 40.29 µm in the thoracic region, and 150.89 ± 69.25 µm in the lumbar region. This difference in thickness may be attributed to the regional biomechanical properties of the spine. Results from this investigation indicate the presence of a nonremodeling tissue on the cortical endplate of the vertebral body in sheep spines, which attaches the intervertebral disc to the vertebrae. This tissue, if not removed, would likely prevent successful bony attachment to an intervertebral device in spinal fusion studies and total disc replacement surgeries. Anat Rec, 296:736–744, 2013. © 2013 Wiley Periodicals, Inc.     

全脊柱终板抗压强度分布规律的生物力学研究

目的 通过测量全脊柱不同椎体上下终板不同位点的抗压强度,研究全脊柱终板抗压强度的分布规律。方法 选用5具成年男性新鲜脊柱标本(C3~S1),共225个终板。对终板平面49个测试点用平底压头进行压缩加载试验,获得最大破坏载荷。结果 (1) 全脊柱终板抗压强度呈颈腰椎较强、胸椎较弱趋势（P<0.01）。抗压强度自C3~7逐渐减小,在T1水平增大,然后再次逐渐减小,至T7降至最低,自T8开始增强,至L4达到强度最大值,L5复又降低后,S1再次增大。(2) 除C5 和T1外,下终板抗压强度大于上终板（P<0.01）。(3) 除C5/6, T12/L1 和L5/S1间隙外,椎间隙相邻面上一椎体下终板的抗压强度大于下一椎体上终板。(4)中央至外周抗压强度逐渐增大（P＜0.05）。(5)处于不同角度组的压力点,其抗压强度存在差异（P<0.01）。(6) 全脊柱终板不同节段前后强度分布不同（P<0.01）。C3/4后侧终板强度大于前部,C5~7前后部大体持平,至T1再次后部大于前部,经过T2~5过渡段后,自T6~L3出现前部抗压强度大于后部,L4再次相对均衡,至L5、S1出现后部抗压强度大于前部。结论 全脊柱不同节段终板和终板不同部位的强度分布与脊柱生理弯曲关系密切。抗压强度下终板高于上终板,外周大于中央,椎间隙相邻面上一椎体下终板大于下一椎体上终板。     

Advanced template matching method for estimation of intervertebral kinematics of lumbar spine

Diagnosis of low back pain and other degenerative spinal pathologies can be extremely difficult and, so far, there are not accepted standards. In general, such pathologies are associated with alteration of mechanical properties of spine and, in particular, with the instability of spinal motion. Intervertebral kinematics can be a valuable, objective method to assess the functionality of spinal segments. Fluoroscopic imaging system can provide continuous screening of lumbar tracts during patient's motion, with an acceptable low X-ray dose. Estimation of intervertebral kinematics relies on accurate recognition of vertebrae positions throughout the fluoroscopic sequence: specific vertebrae features are identified and tracked either by manual selection or by automated methods. This study presents a new method of vertebra tracking, based on image template matching of the contour of the vertebral body for an accurate intervertebral kinematics analysis. An image gradient operator was utilized to obtain the vertebral contours; it operates after an edge-preserving smoothing filter designed to reduce low dose X-ray image noise. Once a template is defined for each vertebra, this is used to determine the best vertebral location in each image throughout the fluoroscopic sequence. Accuracy of the proposed method was tested using images of a calibration model. Average error achieved for the intervertebral angle is of the order of 0.4° and approximately 2 mm for the intervertebral centre of rotation. Five fluoroscopic lumbar sequences of healthy volunteers undergoing passive flexion–extension motion were processed. The intervertebral kinematics was compared with other methods (automated and manual) by an estimation of measurement error. Results showed that the current method provides a better representation of the evolution over time of kinematic parameters. In particular, root mean square differences between the current method and a manual selection procedure performed by an experienced and trained clinician resulted 1.3° for the intervertebral angles and 0.9 mm for the intervertebral trajectory. The proposed method provides an effective, automated and objective technique for estimation of intervertebral kinematics of lumbar spine.     

成人颈椎椎弓根螺钉在儿童腰椎应用的可行性

背景：由于1~3岁幼年儿童椎体发育未完全成熟,各种解剖径线相对较成人小得多,尚无幼儿专用的椎弓根螺钉固定器械,现有能够利用的直径最小的椎弓根螺钉是用于成人颈椎侧块或椎弓根固定的钉棒系统。 目的：观察将成人颈椎椎弓根螺钉应用到成年猪颈椎与幼猪腰椎固定后的生物力学对比。 方法：将6具完整新鲜成年猪颈段C3~C6脊椎标本和6具完整8周龄新鲜幼猪腰段脊柱标本自椎间盘及关节处离断,游离成单个椎体,共54个椎体108侧椎弓根。按照标准操作将成人颈椎椎弓根螺钉分别安置在成年猪颈椎标本和幼猪腰椎标本的椎弓根上,应用生物力学方法测试螺钉的最大轴向拔出力。 结果与结论：颈椎标本最大轴向拔出力高于腰椎标本,但差异无显著性意义(P > 0.05);L1椎弓根螺钉的拔出力均值明显小于L3椎弓根螺钉的拔出力均值(P < 0.05);C5椎弓根螺钉的拔出力均值明显大于C3椎弓根螺钉的拔出力均值(P < 0.05);颈椎和腰椎标的骨密度差异有显著性意义(P < 0.01),椎体椎弓根力学数值与椎体骨密度之间存在线性正相关。说明取得了成人颈椎椎弓根螺钉在轴向拉力方面适应于幼儿腰椎的初步实验依据。     

椎弓根的解剖学观测与临床意义

目的 为临床脊柱手术提供形态学资料.方法 对36具成人尸体的整体脊柱标本,使用游标卡尺测量C_3～L_5椎弓根的高和宽.分别计算各节段椎弓根高和宽的均值和标准差,并分段计算颈椎(C_3～C_7)、胸椎、腰椎各段椎弓根高和宽的平均值.结果 C_3～C_7的高和宽分别为6.77mm和5.50mm;胸椎分别为12.30mm和6.37mm;腰椎平均值分别为15.97mm和9.41mm.结论 提供国人椎弓根的解剖学资料,为临床椎弓根螺钉内固定提供应用解剖学基础.     

Morphometric analysis of vertebrae and intervertebral discs as a basis of disc replacement

In this study measurements were obtained from 359 vertebrae and 215 intervertebral discs in an attempt to classify discs by their size. At the cervical and thoracic levels, this attempt was unproductive because of extensive variations. In the lumbar spine, discs were allocated to six size-matched groups. The breadth of marginal rims were also measured with a view to provide surgeons operating on the spine with precise data on disc morphology to facilitate dise replacement.     

Spine Localization in X-ray Images Using Interest Point Detection

This study was conducted to evaluate a new method used to calculate vertebra orientation in medical x-ray images. The goal of this work is to develop an x-ray image segmentation approach used to identify the location and the orientation of the cervical vertebrae in medical images. We propose a method for localization of vertebrae by extracting the anterior—left—faces of vertebra contours. This approach is based on automatic corner points of interest detection. For this task, we use the Harris corner detector. The final goal is to determine vertebral motion induced by their movement between two or several positions. The proposed system proceeds in several phases as follows: (a) image acquisition, (b) corner detection, (c) extracting of the corners belonging to vertebra left sides, (d) global estimation of the spine curvature, and (e) anterior face vertebra detection.