Age-associated changes of cerebral glucose metabolic activity in both male and female deaf children: parametric analysis using objective volume of interest and voxel-based mapping

Quantitative analysis of brain activity in the brains of children requires the establishment of age-associated norms. We investigated regional differences in age-associated changes in fluorodeoxyglucose (FDG) uptake in the developmental brains. From 87 (44 male and 43 female) deaf children from the age of 1 to 15, brain FDG positron emission tomography (PET) images were examined after spatial normalization, smoothing, and global normalization to identify brain regions showing a correlation between FDG uptake and age. Using population-based probabilistic volume of interests (VOIs), an objective VOI analysis was performed where normalized relative FDG uptake was measured and their correlations with age were examined in both genders. For the voxel-based analyses, the correlations with age were examined in a general linear model using statistical parametric mapping (SPM99). Both methods revealed that FDG uptake linearly increases with age both in the bilateral inferior prefrontal/orbitofrontal gyri and the right dorsomedial frontal gyrus and decreases in the inferior temporal gyrus and internal capsule white matter. Male children showed age-associated increases of FDG uptake in the right dorsomedial frontal gyrus, and female children in the left dorsolateral prefrontal cortex and thalamus. These changes in FDG uptake in various brain regions may suggest changes in synaptic density or regional activity resulting from normal maturation or deaf-induced adaptation. Caution should be exercised in interpreting the differences in the brain of child patients when compared with adult control's or with a different gender. Further research will be needed to examine if gender difference is manifested in the development rate of behavioral/cognitive functions in association with the age-associated changes of the right medial frontal (male) or the left dorsolateral prefrontal cortices.     

Intestinal glucose transport using perfused rat jejunum in vivo: model analysis and derivation of corrected kinetic constants

1. The transport model that best describes intestinal glucose transport in vivo remains unsettled. Three models have been proposed: (1) a single carrier, (2) a single carrier plus passive diffusion, and (3) a two-carrier system. The objectives of the current studies were to define the transport model that best fits experimental data and to devise methods to obtain the kinetic constants, corrected for diffusion barrier resistance, with this model. 2. Intestinal glucose uptake was measured during perfusion of rat jejunum in vivo over a wide range of perfusate concentrations and diffusion barrier resistance was determined under identical experimental conditions. The data were fitted to the transport equations that describe the three models with appropriate diffusion barrier corrections, and the kinetic constants were derived by non-linear regression techniques. The fit of each model to the data was assessed using six statistical tests, five of which favoured a model described by a single carrier and passive diffusion. 3. The main conclusions of these studies are: (1) kinetic constants uncorrected for diffusion barrier resistance are seriously in error; (2) values for the derived kinetic constants are strongly dependent on the transport model selected for the data analysis which underscores the need for rigorous model analysis; (3) corrected kinetic constants may be obtained by either non-linear regression or by a simpler graphical analysis once the correct transport model has been selected and diffusion barrier resistance determined; (4) only corrected kinetic constants should be used for inter-species comparisons or to study the effect of specific interventions on intestinal glucose transport.     

Optimization of factor analysis of the left ventricle in echocardiography for detecting wall motion abnormalities

This study has tested solutions to optimize the ability of factor analysis of the left ventricle in echocardiography (FALVE) to detect segmental wall motion abnormalities automatically. On four- and two-chamber views of 38 patients, two factors (one flat curve and one curve describing the contraction-relaxation sequence) were extracted and associated factor images were combined to synthesize a parametric image (constant image in green, positive/negative values of the contraction-relaxation image in red/blue). The segments were graded on the visual and the parametric views. The impact of selecting a whole cardiac cycle, masking the left ventricle and realigning the image sequence on the results, was demonstrated. Systematic realignment had a positive impact, especially for patients with left bundle branch block or pacemaker. After alignment, for the entire population, the absolute concordance was 68.6% and the relative concordance (within one grade) was 99%. Thus, FALVE is promising for detecting segmental wall motion abnormalities. (E-mail: benoit.diebold@egp.ap-hop-paris.fr)     

护理因素对儿童PET/CT脑葡萄糖代谢显像质量的影响

目的:探讨护理因素对患儿PET/CT脑葡萄糖代谢显像质量的影响。方法:24例患儿纳入研究,患儿空腹4 h以上,封闭视听30 min后注射氟代脱氧葡萄糖(18 F-FDG),注射药物后继续封闭视听40 min,然后进行PET/CT检查。对依从性差、显像时不能保持头部静止不动的患儿给予镇静。结果:大于7岁患儿共9例均未镇静,其中2例患儿显像失败,经家属及护理人员安抚及鼓励,再次显像图像达到诊断要求,余7例大于7岁患儿图像均达到诊断要求。小于7岁患儿15例均口服10%水合氯醛镇静后显像,图像均达到诊断要求。结论:护理工作是保障患儿顺利完成PET/CT脑葡萄糖代谢显像,获得高质量图像的重要因素之一。     

Accurate estimation of retinal vessel width using bagged decision trees and an extended multiresolution Hermite model

We present an algorithm estimating the width of retinal vessels in fundus camera images. The algorithm uses a novel parametric surface model of the cross-sectional intensities of vessels, and ensembles of bagged decision trees to estimate the local width from the parameters of the best-fit surface.We report comparative tests with REVIEW, currently the public database of reference for retinal width estimation, containing 16 images with 193 annotated vessel segments and 5066 profile points annotated manually by three independent experts. Comparative tests are reported also with our own set of 378 vessel widths selected sparsely in 38 images from the Tayside Scotland diabetic retinopathy screening programme and annotated manually by two clinicians. We obtain considerably better accuracies compared to leading methods in REVIEW tests and in Tayside tests.An important advantage of our method is its stability (success rate, i.e., meaningful measurement returned, of 100% on all REVIEW data sets and on the Tayside data set) compared to a variety of methods from the literature. We also find that results depend crucially on testing data and conditions, and discuss criteria for selecting a training set yielding optimal accuracy.     

Validation of the depletion kinetic in semiquantitative ultrasonographic cerebral perfusion imaging using 2 different techniques of data acquisition.

OBJECTIVE: To validate the potential of ultrasonographic depletion imaging for semiquantitatively visualizing cerebral parenchymal perfusion with contrast burst depletion imaging (CODIM) in comparison with phase inversion harmonic depletion imaging (PIDIM) in healthy volunteers. METHODS: Thirteen healthy adults were examined with both CODIM and PIDIM in accordance with previously described criteria. In addition to the perfusion coefficient, the time to decrease image intensity to 10% above equilibrium intensity from the initial value and the relative error (deviation of measured data from the fitted model) were evaluated to compare the reliability of both techniques in 3 different regions of interest. RESULTS: Perfusion coefficient values did not show significantly differing values in both groups (1.57-1.64 * 10(-2) s(-1) for CODIM and 1.42-1.58 * 10(-2) s(-1) for PIDIM). The relative error was significantly smaller in the PIDIM group (0.38-0.53 for CODIM and 0.18-0.25 for PIDIM; P < .002). CONCLUSIONS: Phase inversion harmonic depletion imaging proved to be more reliable than CODIM because values of the relative error were significantly lower in PIDIM even in this relatively small cohort. This is of interest because the underlying technique, phase inversion harmonic imaging, is more widely available than contrast burst imaging.     

急性脑栓塞Penumbra机械取栓：1例建模和有限元分析

背景：国内外开展的急性脑栓塞机械取栓的病例较少，使用Penumbra取栓系统机械取栓的病例更少，该种取栓方法对于局部脑血管的影响认识尚不清楚。 目的：通过数值模拟描述Penumbra机械取栓对1例脑栓塞患者局部脑血管的影响。 方法：选取左侧大脑中动脉急性栓塞患者1例，女，77岁。在急诊DSA术中对其各种原始数据进行采集，并使用Penumbra成功机械取栓。术后对其原始数据进行处理，建成“由近及远吸栓法”和“由远及近吸栓法”两种取栓方法的三维数值模型，并进行有限元分析。 结果与结论：成功地完成建模和有限元分析；结果提示：与“由近及远吸栓法”相比，“由远及近吸栓法”的模型有较小的吸栓导管内流速和血栓壁面切应力（P 〈0.01），有较大的血管壁壁面切应力、血管壁变形量（P 〈0.01）和血栓变形量（P 〈0.05）。结果可见Penumbra机械取栓的有限元分析有助于介入医师更加清楚认识自己的操作对患者脑血管的影响，作为一种研究方法值得今后继续探讨。     

Early time points perfusion imaging: theoretical analysis of correction factors for relative cerebral blood flow estimation given local arterial input function

If local arterial input function (AIF) could be identified, we present a theoretical approach to generate a correction factor based on local AIF for the estimation of relative cerebral blood flow (rCBF) under the framework of early time points perfusion imaging (ET). If C(t), the contrast agent bolus concentration signal time course, is used for rCBF estimation in ET, the correction factor for C(t) is the integral of its local AIF. The recipe to apply the correction factor is to divide C(t) by the integral of its local AIF to obtain the correct rCBF. By similar analysis, the correction factor for the maximum derivative (MD1) of C(t) is the maximum signal of AIF and the correction factor for the maximum second derivative (MD2) of C(t) is the maximum derivative of AIF. In the specific case of using normalized gamma-variate function as a model for AIF, the correction factor for C(t) (but not for MD1) at the time to reach the maximum derivative is relatively insensitive to the shape of the local AIF.     

进展性脑梗死多因素回归分析及判别模型建立

目的:建立进展性脑梗死判别预测模型,为早期发现和干预治疗提供科学依据。方法:使用Logistic逐步回归分析关键影响因素,采用逐步Bayes判别法对进展性脑梗死患者的关键因素进行筛选,并建立判别预测模型。结果:判别模型为:(1)Y1(进展)=-30.381±8.025×X7±1.341×X8±2.301×X21±3.931×X31±5.802×X32±0.933×X33±2.119×X34。(2)Y2(非进展)=-21.875±6.834×X7±2.160×X8±3.328×X31±3.726×X32±2.016×X21±0.861×X33±1.807×X34(X7为平均收缩压,X8为体温,X21为血糖,X31为FIB,X32为颈动脉斑块性质,X33为颈动脉狭窄程度,X34为梗死部位)。经评价预测效果较好。结论:判别模型的建立有助于进展性脑梗死的早期诊断分析及早期干预和治疗。     

Modeling relationships in clinical research using path analysis Part II: evaluating the model

Column Editor: Lauren Clark Scientific Inquiry provides a forum to facilitate the ongoing process of questioning and evaluating practice, presents informed practice based on available data, and innovates new practices through research and experimental learning.     

Quantification of cerebral A1 adenosine receptors in humans using [F]CPFPX and PET: an equilibrium approach

The cerebral A(1) adenosine receptor (A(1)AR) has recently become accessible for in vivo imaging using the selective A(1)AR ligand [(18)F]CPFPX and PET. For broad application in neurosciences, imaging at distribution equilibrium is advantageous to quantify stimulus-dependent changes in receptor availability and to avoid arterial blood sampling. Here we propose a bolus/infusion (B/I) protocol to assess the total distribution volume (DV(t)) of [(18)F]CPFPX under equilibrium conditions. Employing a bolus-to-infusion ratio of 0.8 h, (near) equilibrium conditions were attained within 60 min. The regional DV(t)' given by arterial and venous equilibrium analyses agreed well with conventional two-tissue compartment model analyses (r(2) > 0.94 and r(2) > 0.84, respectively) and Logan's graphical analyses (r(2) = 1.0 and r(2) > 0.93, respectively) (n = 4 healthy volunteers). The mean regional DV(t)' values of these equilibrium analyses and of venous equilibrium analyses in additional seven volunteers demonstrated excellent agreement with the results of earlier bolus studies (r(2) > 0.98). Error simulations show that minor deviations from true equilibrium are associated with negligible to small DV(t) errors. In conclusion, [(18)F]CPFPX shows suitable characteristics for A(1)AR quantification by B/I PET scanning. Carefully standardized venous equilibrium analyses may substitute arterial analyses and thus considerably enhance applicability of A(1)AR PET in clinical routine.     

能谱CT成像碘(水)图纹理分析预测结直肠癌微卫星不稳定状态

目的 探讨基于能谱CT成像碘（水）图像的纹理分析在术前预测结直肠癌微卫星不稳定（MSI）状态方面的价值。方法 回顾性分析23例MSI结直肠癌（MSI组）及46例微卫星稳定（MSS）结直肠癌（MSS组）患者的资料。所有患者均经术后病理检查证实，且术前均接受腹部能谱CT成像。采用Viewer分析软件获取动脉期及静脉期碘（水）图像，并将其导入Omni-Kinetics软件进行ROI勾画及特征提取。提取的纹理参数包括最小值、最大值、平均值、中位值、标准差、偏度、峰度、均匀性、能量值、熵。比较2组间各纹理参数的差异。并采用Logistic回归将纹理参数进行联合，通过ROC曲线分析不同纹理参数预测及多种参数联合预测的效能。结果 MSI组动脉期及静脉期最小值、最大值、平均值、中位值、均匀性均明显低于MSS组（P均<0.05），2组间标准差、偏度、峰度、能量值差异均无统计学意义（P均>0.05）；MSI组静脉期熵明显高于MSS组（t=1.81，P=0.04），2组间动脉期熵差异无统计学意义（t=0.22，P=0.80）。ROC曲线分析显示，以动脉期及静脉期最小值、最大值、平均值、中位值、均匀性和静脉期熵单一参数在术前预测结直肠癌MSI状态的AUC为0.64~0.82。多参数联合的Logistic回归模型为-2.598-0.124×动脉期最小值-0.039×动脉期最小值-0.774×动脉期中位值+1×动脉期平均值-1.892×动脉期均匀性+0.14×静脉期最小值+0.2×静脉期最大值+0.343×静脉期中位值-0.61×静脉期平均值+13.711×静脉期均匀性-2.598×静脉期熵，联合预测的AUC为0.83。结论 基于能谱CT成像碘（水）图像纹理分析，可在术前无创预测结直肠癌MSI状态，且将多种纹理参数联合后预测效能更优。     

以数学模型分析脑缺血-再灌注大鼠缺血半暗带的磁共振成像数据信息

背景:多数学者认为广义的缺血半暗带位于严重缺血区周围的低灌注区,处于动态变化过程,能否成功挽救半暗带成为正常灌注区,是治疗过程中的关键.磁共振能够观察脑缺血的面积,但其数据不能直观地反映缺血时间和脑梗死面积之间的变化规律.目的:观察数学模型在大鼠脑缺血-再灌注模型缺血半暗带磁共振成像中的应用效果.方法:制作大鼠大脑中动脉闭塞缺血模型,分为永久缺血组和神经保护剂组,神经保护剂组于造模成功后经鼠尾静脉注射临床常规神经保护剂灯盏花素注射液.在0.5～48 h内行弥散加权成像检查,测定缺血灶不同部位的表观弥散系数,计算病侧与对侧正常组织的相对值,即相对表观弥散系数.应用最小二乘法进行数据处理,得出缺血时间和梗死面积的函数关系式,并进行线性分析.结果与结论:大鼠脑缺血-再灌注模型即相对表观弥散系数在永久缺血组9～21 h时段3,4点时间(X)和相对表观弥散系数值(Y)呈负相关,且两者线性关系显著,回归方程分别为y=1.458 153-0.042 770 333x,y=1.510 346-0.037 141 333x.在1～6 h时间段均有r＞0,P＜0.05,故变量X与Y呈正相关,且线性关系显著.从24～48 h,1,2,3,4点的相对表观弥散系数值均随时间增加而增加.提示1～6 h时间段是缺血再灌注鼠脑模型神经保护的关键时期.     

High-resolution dynamic MR imaging of the thorax for respiratory motion correction of PET using groupwise manifold alignment

Respiratory motion is a complicating factor in PET imaging as it leads to blurring of the reconstructed images which adversely affects disease diagnosis and staging. Existing motion correction techniques are often based on 1D navigators which cannot capture the inter- and intra-cycle variabilities that may occur in respiration. MR imaging is an attractive modality for estimating such motion more accurately, and the recent emergence of hybrid PET/MR systems allows the combination of the high molecular sensitivity of PET with the versatility of MR. However, current MR imaging techniques cannot achieve good image contrast inside the lungs in 3D. 2D slices, on the other hand, have excellent contrast properties inside the lungs due to the in-flow of previously unexcited blood, but lack the coverage of 3D volumes. In this work we propose an approach for the robust, navigator-less reconstruction of dynamic 3D volumes from 2D slice data. Our technique relies on the fact that data acquired at different slice positions have similar low-dimensional representations which can be extracted using manifold learning. By aligning these manifolds we are able to obtain accurate matchings of slices with regard to respiratory position. The approach naturally models all respiratory variabilities. We compare our method against two recently proposed MR slice stacking methods for the correction of PET data: a technique based on a 1D pencil beam navigator, and an image-based technique. On synthetic data with a known ground truth our proposed technique produces significantly better reconstructions than all other examined techniques. On real data without a known ground truth the method gives the most plausible reconstructions and high consistency of reconstruction. Lastly, we demonstrate how our method can be applied for the respiratory motion correction of simulated PET/MR data.     

Importance of wall motion analysis in the diagnosis of left main disease using stress nuclear myocardial perfusion imaging

We describe a case of a 54-year-old male who underwent exercise technetium-99m sestamibi myocardial perfusion imaging prior to his renal transplantation. With exercise, the patient's myocardial perfusion imaging did not show any transient or fixed myocardial perfusion abnormalities due to balanced ischemia. However, wall motion analysis showed a new global left ventricular systolic dysfunction on post-exercise images. Coronary angiography showed severe left main coronary lesion involving ostia of left anterior descending, ramus intermedius and left circumflex coronary arteries with moderate right coronary artery disease. If one had used the perfusion imaging alone in this patient, the severe multivessel disease including left main coronary disease could have been missed. In this article we emphasize the importance of wall motion analysis in patients undergoing myocardial perfusion imaging.     

超声造影评估颈动脉斑块新生血管分级预测脑梗死再发的Logistic回归模型分析

目的采用Logistic回归模型分析超声造影评估颈动脉斑块新生血管分级预测脑梗死再发的价值。 方法选取2013年4月至2014年5月在浙江省人民医院神经内科就诊的初发脑梗死患者89例,行常规超声与超声造影检查并进行颈动脉斑块的二维回声及新生血管分级,随访1年后入选者脑梗死再发情况,以脑梗死再发与否作为因变量,以年龄、性别、高血压、糖尿病、高脂血症、吸烟史、饮酒史、颈动脉斑块二维回声分级及新生血管分级为自变量,采用Logistic回归模型分析脑梗死再发的独立风险因素,并采用ROC曲线评估独立风险因素预测脑梗死再发的价值。 结果单因素Logistic回归模型分析显示颈动脉斑块二维超声分级（P=0.028）与新生血管分级（P=0.006）为脑梗死再发的风险预测因素,多因素Logistic回归模型分析显示颈动脉斑块新生血管分级是脑梗死再发的独立风险预测因素（OR=1.916,P=0.043）,ROC分析示以新生血管分级>Ⅱ级预测脑梗死再发的敏感度与特异度分别为67.74%、70.69%,其曲线下面积为0.684（95%CI：0.577~0.779,P=0.0017）。 结论超声造影评估颈动脉斑块新生血管分级是预测脑梗死再发的独立风险因素。