MRA与CTA头部血管成像技术探讨

目的 :探讨MRA与CTA成像技术的临床应用 ,选择合适的影像后处理方法。方法 :抽取MRA与CTA各 2 0份影像进行分析。结果 :两组病例MRA与CTA扫描后及处理均获得较好的影像信息。结论 :MRA与CTA的影像检查技术对临床诊断与治疗均各具有其优势并有其重要价值。     

虹膜夹型有晶状体眼人工晶状体植入术对高度近视眼对比敏感度的影响

目的 研究虹膜夹型有晶状体眼人工晶状体（iris-claw phakic intraocular lens，ICPIOL）植人术后对比敏感度（contrastsensitivity，CS）的变化。方法 2005年5月至12月于温州医学院附属眼视光医院和中山大学中山眼科中心接受ICPIOL（Verisyse，美国AMO公司）植入术的高度近视眼患者12例（23只眼），分别在术前、术后1、3、6个月采用CS测试灯箱（CSV-1000型，美国Vector Vision公司）检查暗视状态下无／有眩光时的对比敏感度函数（contrast sensitivity function，CSF）。结果 术后1、3、6个月等效球镜度数分别为（-0．60±0．77）D，（-0．48±0．77）D，（-0．34±0．53）D，与术前（-15．53D±3．65D）差异均有显著统计学意义（P均〈0．001），最佳矫正视力（IogMAR）分别为0．064-0．12，0．02±0．09，-0．003±0．08，与术前（0．21±0．12）差异均有显著统计学意义（P均〈0．001）。术后各空间频率的CS与术前比较有增高趋势。术后3个月6、12、18周／度的CS在无眩光时和有眩光时均明显提高（P均〈0．01），开始接近正常范围。术后3、6个月在各空间频率上CS差异均无统计学意义（P均〉0．05）。结论 ICPIOL植入术矫治高度近视眼可以使CSF恢复到接近正常范围，显著改善视功能，是一种适用于高度乃至超高度近视眼的可供选择的屈光手术。     

Effects of convergent strabismus on spatio-temporal response properties of neurons in cat area 18

Summary Single-cell recording experiments were carried out to determine whether rearing kittens with surgically induced convergent strabismus (esotropia) alters the development of receptive field (RF) properties of neurons in area 18. In agreement with previous work on kittens with divergent strabismus (exotropia), there was a marked loss of binocularly driven cells in area 18 of esotropic cats. In contrast to the striate cortex of strabismic cats, the spatial properties of area 18 neurons, including receptive-field size and spatial frequency tuning, did not differ from those in normal controls. On the other hand, we found that contrast thresholds, measured at an optimal spatial frequency, were significantly elevated, and that the contrast gain in many cells was reduced in strabismic cats. These deficits were observed in both eyes, though the cells dominated by the deviating eye had a lower response amplitude at all contrasts. Furthermore, temporal frequency tuning curves were abnormal in strabismic cats in that the optimal frequencies and temporal resolutions were shifted to lower values. These effects were also bilateral. Velocity tuning, measured with a high-contrast bar stimulus, revealed that area 18 neurons in strabismic cats were unable to respond to very high velocities compared to normals. This reduced response was more severe when measured with the deviating eye in spite of the bilateral nature of the deficit. Finally, latencies to electrical stimulation of the optic chiasm or the optic radiation were significantly longer in strabismic cats. The magnitude of these effects was virtually the same for both eyes. From these observations, we conclude that the temporal properties of area 18 neurons, particularly the cells abilities to follow fast temporal modulations, are affected by raising kittens with surgically induced convergent strabismus.     

超声波介导的基因输送技术

近年来超声波介导的基因输送技术由于其相对安全性和操作上的简单得到关注。本文对超声波导致的声致穿孔的机制,空化核的作用——增强基因输送的效率,以及细胞和在体基因输送效率作了综述,讨论了超声波介导的基因输送效率的影响因素。此方法充满希望并且载药的空泡可以作为一种新型药物载体在超声作用下实现药物的靶向输送     

Binocular suppression in cortical neurons

Summary Dichoptic presentation of patterns similar in shape but of very different contrast results in the perception of only the high contrast pattern (binocular suppression). When recording from binocular neurons of the cat visual cortex, we have found an effect which is strikingly similar to this perceptual phenomenon. If a high and a low contrast grating are presented simultaneously, one to each eye, the cell's response to the low contrast stimulus is suppressed.     

Pontine veins. MRI cross-sectional anatomy

Summary The pons is covered by a rich venous network offering numerous vascular landmarks in MRI and during surgery. We present an original study of the veins as they appear on MR multiplanar scans after gadolinium IV injection. This prospective study is based on 40 consecutive patients with normal posterior fossa structures. One of the major venous collectors follows the pons: the superior petrosal v. was identified on MRI in 95% of our cases. Its hooklike extremity drains into the superior petrosal sinus. The inferior petrosal v. was never identifiable. The superficial pontine venous network are identified in 72.5% of cases in the axial plane and were organised in longitudinal and transverse collectors, whose MR aspects are presented here.

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Les veines du pont. Anatomie sectionnelle en IRM

Résumé Le pont, enveloppé des citernes subarachnoïdiennes, est parcouru à sa surface par de nombreux vaisseaux qui constituent autant de points de repère topographiques en IRM que de rapports chirurgicaux. Nous présentons une étude de l'anatomie veineuse en coupe telle que l'IRM la révèle après injection de Gadolinium. Cette étude prospective comporte 40 patients indemmes de lésion de la fosse crânienne postérieure. Le pont est longé par un des collecteurs majeurs du tronc cérébral : la v. pétreuse supérieure, identifiée dans 95 % des cas. Elle se jette par un crochet caractéristique dans le sinus pétreux supérieur. La v. pétreuse inférieure n'a jamais été reconnue. Les vv. pontiques forment un réseau maillé visible dans 72,5 % des cas en coupes axiales et comportant des axes transversaux et longitudinaux dont les critères d'identification sont présentés selon le plan de coupe.

     

Afterimages of sinusoidal, square-wave and compound gratings

Negative afterimages were observed after steady fixation of sinusoidal gratings at low spatial frequencies, and quantified using contrast-matching and cancellation methods. Afterimage contrast increased as a power function of "exposure", defined as the product of inspection contrast and inspection duration. A single function, linear on a log-log plot, describes the afterimages of gratings at different spatial frequencies, contrasts and durations. The matching method yielded a lower slope (about 0.42) than the cancellation method (0.62), probably because contrast adaptation attenuates perceived afterimage contrast in the first method, but not the second. Square-wave gratings, and those containing two or three harmonic components gave much weaker afterimages (assessed by contrast-matching) than sine-waves did. Contrast adaptation may again be responsible. Hemi-field asymmetries in contrast perception were noted. The contrast of real gratings and afterimages was nearly additive, especially at lower exposures, but the results cannot distinguish between linear filter and gain control models of "local adaptation".     

Binocular contrast summation—II. Quadratic summation

Quadratic summation is presented as a rule that describes binocular contrast summation. The rule asserts that for left-eye and right-eye contrasts C_L and C_R, there is an effective binocular contrast C given by the formula:$C=\sqrt{{(C_L)}^2+{(C_R)}^2}.$Pairs of left-eye and right-eye stimuli that produce equal values of C are equivalent. Quadratic summation is applied to the results of experiments in which stimuli presented to the two eyes differ only in contrast. It provides a good, first-order account of binocular summation in contrast detection, contrast discrimination, dichoptic masking, contrast matching and reaction time studies. A binocular energy-detector model is presented as a basis for quadratic summation.     

患者知情同意权代为行使的案例分析及启示

以医疗典型纠纷案例为例,通过厘清相关法律对患者知情同意权行使及代为行使的相关规定,探讨知情同意权代为行使行为的界定。启示如下:知情同意权代为行使应设前置条件进行限制和约束;代为行使主体包括近亲属或关系人、委托代理人;患者本人意见具有首要优先性,委托代理人意见应优先于近亲属意见。     

大鼠骨骼肌钝挫伤模型的超声造影图像特征与微血管分布的相关性分析

目的 建立重物打击致大鼠骨骼肌钝挫伤模型,动态观察大鼠骨骼肌在损伤修复不同时期肌肉组织的超声造影（CEUS）图像特征,通过计算机辅助定量分析造影剂平均回声强度值（Mean）变化,并与微血管平均光密度值(MVD)进行相关分析。方法 将48只SD大鼠随机分为8组,其中6只大鼠作为正常对照组,余42只大鼠作为实验组,以自制重力锤选定右侧股直肌肌腹中段为打击中心,采用自由落体击落架,用800g的重物,一次性自由落体,建立大鼠下肢骨骼肌钝挫伤模型,分别于损伤后1 h、12h、24h、48h、7d、14d、28d时行CEUS检查,并利用计算机辅助定量分析CEUS图像变化特征,获得各组受损骨骼肌造影剂平均回声强度值（Mean）。在每个时间节点将该组大鼠全部处死,并切取损伤肌肉组织进行HE染色以及通过评估各组织CD34免疫组化来计算微血管平均光密度值（MVD）。结果 （1）CEUS图像变化：损伤后1h-12h各组大鼠打击部位肌肉造影剂信号微弱,可见充盈缺损;损伤后24h组损伤区造影剂呈星点状分布,为弱增强;48h组造影剂表现为斑片状分布,为轻度增强;损伤后7d组损伤区造影剂信号密集增多,呈高增强;损伤后14d组损伤区造影剂信号较7d组减少,呈轻度增强,损伤后28d组,造影剂信号进一步减少,与对照组相似,呈弱增强。（2）计算机辅助定量分析CEUS图像的Mean变化：与对照组比较,损伤后1h、12h、24h各组损伤区内Mean均明显减低（14.99±3.65 vs 3.99±0.97、14.99±3.65 vs 5.74±1.68 、14.99±3.65 vs 5.55±1.62),P均＜0.05;损伤后48h组损伤区Mean增高（14.99±3.65 vs 20.02±7.41）,P＞0.05;损伤后7d组损伤区Mean明显增高（14.99±3.65 vs 59.98±10.13）,P＜0.05;损伤后14d组损伤区Mean较7d组减低,（14.99±3.65 vs 27.11±4.67）,P＜0.05;损伤后28d组,Mean接近正常对照组水平（14.99 ±3.65 vs 16.02±3.97）,P＞0.05。 （3）各实验组损伤区Mean与微血管平均光密度值（MVD）具有线性正相关（r=0.840,P＜0.001）。结论 重物打击建立的大鼠下肢骨骼肌钝挫伤模型,在损伤后1h-48h肌肉炎症反应明显,7d-28d呈修复趋势。超声造影（CEUS）可动态观察受损骨骼肌不同时期的微循环灌注演变,计算机辅助图像分析可快速定量描述超声造影剂平均回声强度值变化,且与肌肉内微血管分布规律相关性较好。