Precision and Accuracy of Measurements on CT Scout View

ObjectivesThe purposes of this study were to (1) investigate the limits of measurements on scout view in three computed tomography axes, x, y and z and (2) develop a model to provide better understanding of measurement accuracy.MethodsFor the first objective, anteroposterior and lateral scout views of a Catphan phantom 200 mm in diameter and length were acquired with a GE scanner at 21 different table heights. Phantom measurements on scout view were performed by two experienced readers. The comparison of their measures provided estimation of precision. The accuracy was assessed by determining the bias, calculated as the difference between the values measured on scout view and the real phantom size. Second, a model was developed investigating the relationship between the dimensions of the object, its image, and the table height. This relationship was tested on our data.ResultsScout view measurements were precise, with less than 0.53% difference between readers. In addition, small biases of about 1 mm were detected in the z-axis, whatever the table height. In the other axes, serious biases from −13 to +73 mm were measured. Furthermore, at isocentre, overestimations up to 7 mm were shown. The results also indicated that biases in scout view measurements are because of the geometrical projection related to the object-detector distance.ConclusionsMeasurements in the table movement axis are precise and accurate, conferring to scout views an added value for preoperative planning in orthopedic surgery.     

Pediatric cardiac computed tomography angiography: Expert consensus from the Filiale de Cardiologie Pédiatrique et Congénitale (FCPC) and the Société Française d’Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV)

This article was designed to provide a pediatric cardiac computed tomography angiography (CCTA) expert panel consensus based on opinions of experts of the Société Française d’Imagerie Cardiaque et Vasculaire diagnostique et interventionnelle (SFICV) and of the Filiale de Cardiologie Pédiatrique Congénitale (FCPC). This expert panel consensus includes recommendations for indications, patient preparation, CTA radiation dose reduction techniques, and post-processing techniques. The consensus was based on data from available literature (original papers, reviews and guidelines) and on opinions of a group of specialists with extensive experience in the use of CT imaging in congenital heart disease. In order to reach high potential and avoid pitfalls, CCTA in children with congenital heart disease requires training and experience. Moreover, pediatric cardiac CCTA protocols should be standardized to acquire optimal images in this population with the lowest radiation dose possible to prevent unnecessary radiation exposure. We also provided a suggested structured report and a list of acquisition protocols and technical parameters in relation to specific vendors.     

冠状CT扫描对颅脑疾患的诊断意义

作者通过对30例颅脑疾患冠状CT扫描资料进行研究,提出在一定情况下,在横断CT扫描的基础上,加用冠状CT扫描或冠矢重建图象,对病变的精确定位、病变的起源和发展方向以及病变与周围结构的关系等很有裨益。     

轴突分叉点位置计算法适用性的分析

某些中枢神经元通过分叉轴突向两个以上核团投射。轴突分叉点的位置通常由计算轴突主干传导时间予以估测。但是,本工作用该法的4个公式计算细胞内或细胞外记录到的数据未能得到一致和可信的数值。结果提示,计算法的原理是不合理的,并至少对在细胞内或细胞外记录条件下估测轴突分叉点是不适用的。     

胸部螺旋CT最大密度投影重建的参数优化

目的探讨胸部螺旋CT最大密度投影(MIP)重建合理的扫描和重建参数。方法6例煤工的尸检离体肺脏制成充气固定肺标本,分别行不同参数组合的螺旋CT扫描,包括层厚1.5mm,2mm,4mm及8mm,重建间隔1mm,3mm,5mm;曝光量150mA,100mA;螺距1.5;滤过算法包括标准、锐利和平滑3种。每组图像均行MIP重建,重建厚度为12.5mm～13mm,比较不同参数MIP重建图像对支气管血管束的显示。结果a)曝光量对MIP重建图像的影响甚微,150mA、100mA两组剂量MIP无显著性差异(P>0.05);b)重建算法对MIP重建无显著影响。c)扫描层厚影响MIP图像,以薄层(1.5mm)扫描重建为最佳,1.5mm、2mm、4mm层厚MIP图像之间无显著性差异(P>0.05),8mm层厚与前4者MIP图像有显著性差异(P<0.01)。d)重建间隔影响MIP重建效果,8mm层厚扫描,1mm和5mm重建间隔重建图像MIP之间有显著性差异(P<0.05)。结论影响MIP重建的参数主要为扫描层厚和重建间隔,薄层扫描可获得理想的MIP图像,随层厚的增加,减小重建间隔有利于获得理想的MIP图像。建议以中等层厚(4mm)扫描,小重建间隔(1.5mm,2mm)行MIP重建。     

Estimating neuron dendritic length in 3D from total vertical projections and from vertical slices

The recently developed method of total vertical projections is illustrated to estimate the total dendritic length of a human Substantia Nigra neuron. Next, the length of the different orders of dendritic branches, and the mean segment length for each order - commonly regarded as important parameters in neuron physiology - are also estimated. Finally, it is shown how to estimate the mean dendritic length in a population of neurons from vertical slices of arbitrary and unknown thickness. Being unbiased and highly efficient, the proposed methods offer interesting alternatives to current procedures used for the metric analysis of neuron arborizations.     

Cortical projection patterns of magnocellular basal nucleus subdivisions as revealed by anterogradely transportedPhaseolus vulgaris leucoagglutinin

The present paper deals with a detailed analysis of cortical projections from the magnocellular basal nucleus (MBN) and horizontal limb of the diagonal band of Broca (HDB) in the rat. The MBN and HDB were injected iontophoretically with the anterograde tracer Phaseolus vulgaris leucoagglutinin (PHA-L). After immunocytochemical visualization of labeled efferents, the distribution of projections over the cortical mantle, olfactory regions and amygdala were studied by light microscopy. Based on differences in cortical projection patterns, the MBN was subdivided in anterior, intermediate and posterior portions (MBNa, MBNi and MBNp). All subdivisions maintain neocortical projections and are subject to an anterior to posterior topographic arrangement. In the overall pattern, however, the frontal cortex is the chief target. Furthermore, all MBN parts project to various regions of meso- and allocortex, which are progressively more dense when the tracer injection is more anteriorly placed. The most conspicuous finding, however, was a ventrolateral to dorsomedial cortical projection pattern as the PHA-L injection site moved from posterior to anterior. Thus, the posterior MBN projects predominantly to lateral neo- and mesocortex while the anterior MBN sends more fibers to the medial cortical regions. Furthermore, the MBNa is a source of considerable afferent input to the olfactory nuclei and as such should be regarded as a transition to the HDB. The HDB, apart from projecting densely to olfactory bulb and related nuclei, maintains a substantial output to the medial prefrontal cortical regions and entorhinal cortex, as well. Comparison of young vs aged cases indicate that aging does not appear to have a profound influence on cortical innervation patterns, at least as studied with the PHA-L method.     

薄块MIP在听小骨显示中的作用评价

目的探讨通过多层螺旋CT各向同性扫描进行薄块最大密度投影(th in slab m aximum intensity projection,ts-M IP)后处理对听小骨的显示能力。方法对35例患者行多层螺旋CT各向同性扫描,然后在工作站进行ts-M IP后处理,观察横断面、冠状面和矢状面ts-M IP对听小骨的显示情况。结果横断面、冠状面和矢状面ts-M IP均能对锤骨、砧骨及锤砧关节进行显示,其中横断面ts-M IP显示砧镫关节较好,并可同时显示锤骨柄及砧骨长脚的全长;冠状面ts-M IP可显示锤骨的全貌;矢状面ts-M IP显示听小骨可很好地避免各结构地重叠。结论通过多层螺旋CT各向同性扫描获得的图像进行ts-M IP后处理,能够很好地显示正常锤骨、砧骨及砧镫关节,其缺点是对镫骨的显示欠佳。     

Vessel-encoded arterial spin-labeling using pseudocontinuous tagging.

A new signal-to-noise ratio (SNR) efficient method is introduced for the mapping of vascular territories based on pseudocontinuous arterial spin labeling (ASL). A pseudocontinuous tagging pulse train is modified using additional transverse gradient pulses and phase cycling to place some arteries in a tag condition, while others passing through the same tagging plane are in a control condition. This is combined with a Hadamard or similar encoding scheme such that all vessels of interest are fully inverted or relaxed for nearly all of the encoding cycles, providing optimal SNR. The relative tagging efficiency for each vessel is measured directly from the ASL data and is used in the decoding process to improve the separation of vascular territories. High SNR maps of left carotid, right carotid, and basilar territories are generated in 6 min of scan time.     

Difference in projections to the lateral and medial facial nucleus: anatomically separate pathways for rhythmical vibrissa movement in rats

Summary The present paper demonstrates that the lateral and medial subdivisions of the rat facial motor nucleus (NVII) receive differing mesencephalic and metencephalic projections. In order to study brain projections to facial nucleus, horseradish peroxidase (HRP) was injected iontophoretically into the entire facial nucleus or the following subdivisions: lateral, dorsolateral, medial, intermediate, and ventral. In the mesencephalic region, the retrorubral nucleus was found to project to the contralateral medial subdivision of NVII, while the red nucleus was found to project to the contralateral lateral subdivision of NVII. Other mesencephalic projections to the facial nucleus arose from the deep mesencephalic nucleus, oculomotor nucleus, central gray including inter stitial nucleus of Cajal and nucleus Darkschewitsch, superior colliculus and substantia nigra (reticular). In the metencephalic region, the Kölliker-Fuse nucleus, parabrachial nucleus, and the ventral nucleus of the lateral lemniscus projected mainly to the ipsilateral lateral subdivision of NVII. In addition, the trapezoid, pontine reticular, vestibular, and motor trigeminal nuclei were observed to have predominantly ipsilateral connections to the facial nucleus. In contrast, projections from the myelencephalic region were to both the lateral and medial subdivision of NVII. The medullary reticular nucleus, ambiguus nucleus, spinal trigeminal nucleus and parvocellular reticular nucleus projected to both lateral and medial subdivisions of NVII with an ipsilateral predominance. The gigantocellular and paragigantocellular reticular nuclei, raphe magnus, external cuneate nucleus and the nucleus of the solitary tract also projected to the facial motor nucleus. Surprisingly, no direct projections to the NVII were observed from diencephalic and telencephalic regions. Our findings that the lateral subdivision of NVII which innervates vibrissa-pad-muscles (Dom et al. 1973; Martin and Lodge 1977; Watson et al. 1982) receives different metencephalic and mesencephalic projections than medial subdivision which controls pinna movement (Henkel and Edwards 1978), suggest that the functional difference between these subdivisions is mediated by the anatomically separate pathways. We confirmed our anatomical findings by eliciting exclusively vibrissa responses by electrical stimulation of the nuclei which project to the lateral subdivision of NVII.