Diagnostic value of 3 D CT surface reconstruction in spinal fractures

Our purpose was to evaluate the diagnostic value of three-dimensional (3 D) CT surface reconstruction in spinal fractures in comparison with axial and reformatted images. A total of 50 patients with different CT-proven spinal fractures were analysed retrospectively. Based on axial scans and reformatted images, the spinal fractures were classified according to several classifications as Magerl for the thoraco-lumbar and lower cervical spine by one radiologist. Another radiologist performed 3 D CT surface reconstructions with the aim of characterizing the different types of spinal fractures. A third radiologist classified the 3 D CT surface reconstruction according to the Magerl classification. The results of the blinded reading process were compared. It was checked to see in which type and subgroup 3 D surface reconstructions were helpful. Readers one and two obtained the same results in the classification. The 3 D surface reconstruction did not yield any additional diagnostic information concerning type A and B injuries. Indeed, the full extent of the fracture could be easier recognized with axial and reformatted images in all cases. In 10 cases of C injuries, the dislocation of parts of vertebrae could be better recognized with the help of 3 D reconstructions. A 3 D CT surface reconstruction is only useful in rotational and shear vertebral injuries (Magerl type C injury). Received: 29 May 1995; Accepted: 11 January 1996     

螺旋CT脊髓及椎间盘三维成像在脊柱损伤中的应用价值

目的　探讨螺旋CT脊髓及椎间盘三维重建在脊柱外伤中的应用价值。方法　选取脊柱外伤病人 78例 ,经CT轴位平扫后对原始数据进行回顾性内插重建 ,所有病例均采用三维表面遮盖显示法 (SSD)和矢状位多层面重建 (MPR) ,并与常规横轴位图像 (2DCT)进行三者之间的比较。结果　共检出脊髓正常 2 3例 ,脊髓受压 39例 ,脊髓横断损伤 1 6例 ,椎间盘受损 38例。结论　螺旋CT可对脊髓及椎间盘进行三维立体重建。对脊柱损伤的CT评价可以延伸到直观、立体地观察脊髓及椎间盘受损的形态学表现。对制定合理的治疗方案及对预后的判断有一定的指导意义     

螺旋CT三维和多平面重建在腰椎峡部裂中的应用

目的：探讨螺旋CT（SCT）三维和多平面重建在腰椎峡部裂中的临床价值。资料与方法：分析15例腰椎峡部裂的轴位、多平面重组CT及三维CT表现。结果：最大密度投影（MIP）图像对峡部裂显示良好，15例33处均显示清晰；表面重建（SSD）图像在显示峡部裂方面不及MIP和多平面重组（MPR）图像，仅显示6例9处峡部裂，但在显示椎体滑脱方面效果良好；MPR矢状面和反角度（平行椎弓）轴位重建对15例33处椎弓峡部裂均显示良好，轴位重组对裂隙骨赘、骨痂、纤维组织增生、椎间盘病变等征象显示清晰，正中矢状面重建对椎体滑脱、椎体撕裂或骨赘后突显示良好。结论：SCT三维重建（MIP、SSD）和MPR对腰椎椎弓峡部裂衣其所引起的相关改变具有良好的显示效果，有利于临床制定手术方案。     

Three-dimensional treatment planning for central lymphatic irradiation

The purpose of this study was to investigate the applicability of 3-dimensional (3D) treatment planning for central lymphatic irradiation (CLI). CLI requires more than 1 course of treatment with large, highly blocked, overlapping beams, and careful planning is required to ensure that such treatments are delivered safely and effectively. Three patients were selected for this study. Each patient completed at least 1 course of radiation therapy for CLI and was scheduled to receive irradiation to an adjacent area with overlapping beams. Two treatment plans were generated for each patient: a standard, 2-dimensional (2D) treatment plan and a 3D treatment plan designed to mimic the standard plan, taking advantage of unique 3D features. The time required to complete the treatment plans and differences in the treatment planning processes were noted. The time required to generate a 3D treatment plan was approximately the same as the time required to generate a standard 2D treatment plan; however, the 3D planning process required less redundancy of data entry than the 2D process. The 3D treatment plan was qualitatively similar to the standard 2D treatment plan; however, differences in beam penumbra and beam junctions were noted, and are most likely due to differences in the dose-calculation models used in these 2 treatment planning systems. Dose-volume histograms (DVHs) were calculated for the spinal cord and were found to be useful to the physicians for quickly and accurately evaluating the presence or absence of hot spots in the junction region. 3D treatment-planning has some advantages over 2D treatment planning for CLI; the main advantage of the 3D treatment plan is that it provides a single plan for each patient with multiple views of the data, including different planar cross-sections and DVHs. For the 2D system, a separate plan was generated for each view, requiring redundant data entry. The quality of the output of the 3D treatment plans is superior to that of 2D treatment plans, but the clinical utility is about the same. Currently, the time required for 2D and 3D treatment plans is similar. However, as dosimetrists become more familiar with 3D treatment planning systems, we expect this familiarity and regularity of use to translate into a significant time advantage.     

螺旋CT三维重建在脊柱骨折中的应用

目的探讨螺旋CT3D重建对脊柱骨折的诊断价值。方法70例脊柱骨折患者均经螺旋CT扫描及3D重建。螺旋CT扫描是以层厚3mm～5mm．进床速度3mm／s～5mm／s，电压120kV，电流200mA，薄层重建1mm～3mm进行的。3D重建在工作站上进行。选择重建时合适的阈值，脊柱200HU，分别进行脊柱及周围软组织重建，并用假彩色技术处理。使用不同的旋转轴观察病变，测量有关数据。结果全部病例均被清楚显示骨折线的走行、骨折的部位、类型、严重程度、移位及椎管狭窄状况。结论螺旋CT3D重建对脊柱骨折具有重要诊断价值，简化了观察者的思维过程，并能为选择治疗方案和评价预后提供可靠依据。     

In vivo magnetic resonance imaging of the human cervical spinal cord at 3 Tesla

PURPOSE: To demonstrate the feasibility of obtaining high-quality magnetic resonance (MR) images of the human cervical spinal cord in vivo at a magnetic field strength of 3 T and to optimize the signal contrast between gray matter, white matter, and cerebrospinal fluid (CSF) on 2D gradient recalled echo (GRE) images of the cervical spinal cord. MATERIALS AND METHODS: Using a custom-built, anatomically molded radio frequency (RF) surface coil, the repetition time and flip angle of a 2D GRE sequence were systematically varied in five volunteers to assess tissue contrast in the cervical spinal cord. RESULTS: The 2D GRE parameters for an optimal balance between gray-white matter and CSF-white matter contrast at 3 T were determined to be a time-to-repetition (TR) of 2000 msec and a flip angle of 45 degrees, with the constant short time-to-echo (TE) of 12 msec used in this study. Excellent tissue contrast and visualization of the internal anatomy of the spinal cord was demonstrated reproducibly in eight subjects using these optimal parameters. CONCLUSION: This study demonstrates that imaging the cervical spinal cord and delineating internal spinal cord structures such as gray and white matter is feasible at 3 T.     

High-resolution DTI of a localized volume using 3D single-shot diffusion-weighted STimulated echo-planar imaging (3D ss-DWSTEPI).

Diffusion tensor MRI (DTI) using conventional single-shot (SS) 2D diffusion-weighted (DW)-EPI is subject to severe susceptibility artifacts. Multishot DW imaging (DWI) techniques can reduce these distortions, but they generally suffer from artifacts caused by motion-induced phase errors. Parallel imaging can also reduce the distortions if the sensitivity profiles of the receiver coils allow a sufficiently high reduction factor for the desired field of view (FOV). A novel 3D DTI technique, termed 3D single-shot STimulated EPI (3D ss-STEPI), was developed to acquire high-resolution DW images of a localized region. The new technique completes k-space acquisition of a limited 3D volume after a single diffusion preparation. Because the DW magnetization is stored in the longitudinal direction until readout, it undergoes T(1) rather than T(2) decay. Inner volume imaging (IVI) is used to limit the imaging volume. This reduces the time required for EPI readout of each complete k(x)-k(y) plane, and hence reduces T(2)(*) decay during the readout and T(1) decay between the readout of each k(z). 3D ss-STEPI images appear to be free of severe susceptibility and motion artifacts. 3D ss-STEPI allows high-resolution DTI of limited volumes of interest, such as localized brain regions, cervical spinal cord, optic nerve, and other extracranial organs.     

磁共振3DFIESTA及3DT1SPGR序列显示舌咽神经及血管压迫的诊断价值

 目的探讨磁共振3DFIESTA及3DT₁SPGR序列显示舌咽神经及血管压迫的诊断价值。方法对5例(10根神经)舌咽神经痛患者及17位(34根神经)健康志愿者共44根舌咽神经同时行3DFIESTA及3DT₁SPGR两序列成像,并对图像进行3D后处理重建,对图像质量及血管与舌咽神经的关系进行分析比较。结果两种序列显示舌咽神经图像质量比较,3DFIESTA序列优质图像43根神经(98%)明显多于3DT₁SPGR序列19根神经(43%),而劣质图像3DT₁SPGR序列25根神经(57%),FIESTA序列1根神经(2%)。3DFIESTA序列图像质量明显好于3DT₁SPGR序列(χ²=31.44,P<0.001)。5例舌咽神经痛患者中血管紧贴舌咽神经者6根神经(60%),而健康志愿者血管紧贴舌咽神经者8根神经(23%),舌咽神经痛患者血管紧贴舌咽神经者较健康志愿者多,且与临床表现相符合。结论在舌咽神经检查中利用3DFIESTA序列显示舌咽神经图像质量较好,同时做3DT₁SPGR序列,利用其血管呈现高信号的特点,对舌咽神经痛血管紧贴神经的诊断更加有益。     

Volume fast spin-echo imaging of the cervical spine

RATIONALE AND OBJECTIVES: The authors prospectively evaluated a T2-weighted, three-dimensional (3D) volume, fast spin-echo (SE) pulse sequence in assessment of the cervical spine and compared it with standard imaging protocol. MATERIALS AND METHODS: Eighteen patients with neck pain underwent magnetic resonance (MR) imaging at 1.5 T with two-dimensional (2D) fast SE and axial 3D gradient-echo (GRE) protocols and with an additional sagittal T2-weighted volume fast SE protocol. The spinal cord and canal, neural foramina, and intervertebral disks were assessed by two neuroradiologists, and the results were compared with reports from the standard protocol. The quality of the partition (direct sagittal) and reconstructed images were evaluated. RESULTS: No differences existed in the assessment of spinal cord disease or disk herniation with 2D fast SE and volume fast SE imaging. Some mild variation occurred in assessment of the neural foramina. Partition images demonstrated a high level of resolution and contrast, while reconstructed images had consistently lower quality. However, this did not impede detection and grading of disk or spinal abnormalities, which were adequately shown on volume fast SE sagittal images. Neural foramina were well demonstrated on axial reconstructions from volume fast SE imaging. CONCLUSION: Volume fast SE imaging provides information about the spinal cord, canal, disks, and neural foramina that is comparable to the information provided by routine imaging. Its thinner sections and multiplanar reconstruction capability are advantages over 2D imaging. Its greater tissue contrast with better visualization of the cervical cord, greater signal-to-noise ratio, and less susceptibility artifact are advantages over 3D GRE imaging.     

Upper extremity kinematics during functional activities: three-dimensional studies in a normal pediatric population

Children with brachial plexus birth palsy, burns, cerebral palsy, spinal cord injury and upper limb malformations may have diminished ability to perform activities of daily living (ADLs) due to limited upper extremity (UE) motion. Three-dimensional (3D) imaging techniques provide a way to document multi-planar functional limitations in the UE. These techniques have not been routinely used for this purpose primarily due to a lack of standardized protocols stemming from the complex nature of UE motion. Before 3D techniques can be routinely used for quantitative analysis and determination of functional limitations, standard activities and nomenclature for UE motion must be determined, and normal arm motion defined. This study establishes a normative pediatric database of 3D kinematic values during selected ADLs, enabling future comparisons with pathologic movements. Regardless of their underlying condition, children with limited UE function and ADL performance can be studied using this protocol and compared with this age-matched normal population.     

Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen’s kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences.     

Fusion of multi-planar images for improved three-dimensional object reconstruction

Due to the scan time limitation, our MRI studies of the human tongue can acquire only a limited number of contiguous two-dimensional (2D) slices to form a volumetric data set in a given series. An interpolated three-dimensional (3D) reconstruction using images acquired in a single plane presents artifacts. To address this issue, we developed a wavelet-based bidirectional linear fusion method that uses slices acquired from sagittal and coronal planes to estimate the unknown values of the inter-slice voxels. We use an interpolation method to estimate the voxel value based on neighboring fiducial voxels in the bounding slices. This interpolation is followed by a wavelet fusion to recover image details by integrating prominent coefficients from the interpolated images. Our method was evaluated using 2D MR images and 3D phantoms. Experiments demonstrated that our method reduces interpolation artifacts and greatly improves the 3D reconstruction accuracy. The advantage of our method casts new light on MR imaging and image processing and permits us to achieve high resolution and short acquisition time simultaneously.     

Reconstruction of volumetric ultrasound panorama based on improved 3D SIFT

Registration of ultrasound volumes is a key issue for the reconstruction of volumetric ultrasound panorama. In this paper, we propose an improved three-dimensional (3D) scale invariant feature transform (SIFT) algorithm to globally register ultrasound volumes acquired from dedicated ultrasound probe, where local deformations are corrected by block-based warping algorithm. Original SIFT algorithm is extended to 3D and improved by combining the SIFT detector with Rohr3D detector to extract complementary features and applying the diffusion distance algorithm for robust feature comparison. Extensive experiments have been performed on both phantom and clinical data sets to demonstrate the effectiveness and robustness of our approach.     

16层螺旋CT尿路造影对输尿管结石的诊断

目的:评价16层螺旋CT尿路造影(CTU)及三维重建技术对输尿管结石诊断的临床应用价值.方法:25例患者先行腹部X线片检查,后行CTU检查及三维重建.结果:17例腹部X线片可疑结石患者CTU及三维重建检查确诊输尿管结石14例,8例腹部X线片检查阴性患者CTU及三维重建检查确诊输尿管结石5例.结论:CTU及三维重建技术是诊断输尿管结石极好的影像检查方法,对输尿管结石的诊断及鉴别诊断具有重要价值.     

2D partially parallel imaging with k-space surrounding neighbors-based data reconstruction.

Partially parallel imaging (PPI) achieves imaging acceleration by replacing partial phase encoding (PE) with the spatially localized sensitivity encoding of a receiver surface coil array. Further accelerations can be achieved through 2D PPI along two PE directions in 3D MRI. This paper is to explore the k-space-based PPI acquisition and reconstruction strategies for 3D MRI. A surrounding neighbors-based autocalibrating PPI (SNAPPI) was first presented by generalizing the 2D multicolumn multiline interpolation method. Several 2D PPI reconstruction methods were then provided by applying SNAPPI to recover the partially skipped k-space data along two PE directions separately or nonseparately, in k-space or in the hybrid k and image space. An optimal 2D PPI sampling-based reconstruction approach was also presented for applying PPI along certain spatial direction along which the array coil has not sufficient sensitivity variation for a valid PPI reconstruction. Both simulated and in vivo 2D PPI data were used to evaluate the proposed methods.     

螺旋CT三维成像在诊断面颅骨骨折中的作用

目的　评价螺旋CT三维成像技术在诊断面颅骨骨折中的作用。方法　总结利用螺旋CT三维成像技术处理 2 6例面颅骨骨折患者的影像学资料 ,分析其多平面重建 (MPR) ,三维表面遮盖法重建 (SSD) ,容积重建 (VRT)等多种重建技术的影像学表现。结果　MPR、SSD、VRT可清晰显示面颅骨骨折的位置、形态、大小 ,叠加成像能清楚显示面颅骨骨折与邻近结构关系。结论　 3D重建能立体地显示面颅骨骨折 ,结合轴位图像能提高诊断面颅骨骨折的准确性 ,对临床治疗方案有较大帮助     

脊髓亚急性联合变性15例临床分析

目的　总结脊髓亚急性联合变性的临床特点 ,探讨该病的病因、电生理及其MRI表现。方法　对 15例脊髓亚急性联合变性的临床表现 ,实验室、电生理及MRI检查、常见病因、治疗方法进行了分析。结果　 15例均有后索、侧索及周围神经损害 ,以后索、侧索损害为主者 11例 (73 .3 3 % ) ,以周围神经损害为主者 4例 (2 6.67% ) ,伴精神症状者 3例 (2 0 % ) ,伴视力减退者 4例 (2 6.67% )。检测血清维生素B1 2 11例 ,其中降低 8例 (72 .73 % )、正常 3例 (2 7.2 7% )。MRI检查脊髓异常 2例 ,均为脊髓后索长条状对称性的等 (或 )长T1、长T2信号。结论　脊髓亚急性联合变性是由于维生素B1 2 缺乏以后索、侧索及周围神经损害为主的疾病 ,血清维生素B1 2 降低有助于脊髓亚急性联合变性的诊断 ,但不是一个绝对可靠的指标。脊髓MRI检查对本病具有客观诊断价值。     

螺旋CT扫描和三维重建诊断颌面部骨折的应用价值

目的：研究螺旋CT二维影像和三维影像对显示颌面部骨折的优缺点和临床应用价值。方法：对22例不同类型的颌面部骨折患者进行了螺旋CT薄层扫描和三维重建。结果：对于颌面部骨折的诊断，CT二维和CT三维重建影像不存在明显差异，但CT三维重建对下颌骨髁状突骨折 和Le-Fort各型骨折的显示优于CT二维影像，CT二维影像在发现细小骨折和深部结构骨折及骨折周围软组织改变方面优于CT三维重建。结论：CT二维、CT三维重建对于颌面部骨折的显示各有优缺点，两者结合应用，为最佳检查方法。     

Three-dimensional spiral CT reconstruction in a patient with massive cerebral air embolism

Cerebral air embolism may be caused by iatrogenic or post-traumatic introduction of air into arterial or venous systems. It is usually revealed by computerized tomography. In this paper, we report a case with thorax trauma and loss of consciousness, in whom cerebral massive air embolism was detected and its distribution was demonstrated by using 3D spiral CT reconstruction. To our knowledge, this is the first case in whom 3D spiral CT reconstruction was used for demonstration of cerebral arterial air embolism.     

Techniques, Clinical Applications and Limitations of 3D Reconstruction in CT of the Abdomen

Enhanced z-axis coverage with thin overlapping slices in breath-hold acquisitions with multidetector CT (MDCT) has considerably enhanced the quality of multiplanar 3D reconstruction. This pictorial essay describes the improvements in 3D reconstruction and technical aspects of 3D reconstruction and rendering techniques available for abdominal imaging. Clinical applications of 3D imaging in abdomen including liver, pancreaticobiliary system, urinary and gastrointestinal tracts and imaging before and after transplantation are discussed. In addition, this article briefly discusses the disadvantages of thin-slice acquisitions including increasing numbers of transverse images, which must be reviewed by the radiologist.