Efficient high-frequency body coil for high-field MRI.

The use of body coils is favored for homogeneous excitation, and such coils are often paired with surface coils or arrays for sensitive reception in many MRI applications. While the body coil's physical size and resultant electrical length make this circuit difficult to design for any field strength, recent efforts to build efficient body coils for applications at 3T and above have been especially challenging. To meet this challenge, we developed an efficient new transverse electromagnetic (TEM) body coil and demonstrated its use in human studies at field strengths up to 4 T. Head, body, and breast images were acquired within peak power constraints of <8 kW. Bench studies indicate that these body coils are feasible to 8 T. RF shimming was used to remove a high-field-related cardiac imaging artifact in these preliminary studies. P41RR13230     

英语阅读障碍儿童词汇命名加工特征的研究

目的研究英语阅读障碍儿童操作英语词汇的相关能力 ,探索英语阅读障碍的表现特点与矫治的手段。方法英语真、假词命名实验 ,观察 3 4名阅读障碍儿童和 3 4名对照组儿童的实验结果。结果 ( 1)障碍组右视野在真、假词的命名时间上与对照组存在显著差异 ;( 2 )障碍组在真词和假词上的命名错误率均大于正常组 ,假词命名的错误率大幅增加。 ( 3 )障碍组右视野的真词命名时间明显长于左视野 ,假词命名的错误率也明显大于左视野。结论英语阅读障碍的儿童显示出了操作英语语音能力的欠缺以及左测大脑半球活动水平不足的倾向。     

Ploidy analysis of field cancerization and cancer development in the hamster cheek pouch carcinogenesis model

BACKGROUND: The hamster cheek-pouch carcinogenesis model is a well-known animal system that closely mimics the development of premalignant and malignant lesions in human oral cancer. Our aim was to numerically characterize the premalignant and malignant lesions and expressions of field cancerization in this model using ploidy as the end-point. METHODS: To study the DNA content and proliferation status of the cells in this model we assessed the Feulgen reaction and the immunohistochemical reaction for 5-bromo-2-deoxiuridine (BrdU) in different histological areas of serial tissue sections of the cheek pouches of animals injected with BrdU. RESULTS: Ploidy values were higher in cancerized epithelia with no unusual microscopic features (NUMF), in preneoplastic and tumor areas than in control epithelia. The aneuploidy index was higher in NUMF areas than in control and differed significantly from control in preneoplastic areas and carcinoma. CONCLUSIONS: The unexpected alteration in DNA content observed in NUMF epithelia is of great relevance as a biomarker of field cancerized areas.     

MRI of the fingers in patients with systemic scleroderma. Early results of contrast-enhanced examinations on a dedicated MRI system

Purpose. To estimate disease activity in patients with systemic sclerosis using contrast-enhanced MRI of the skin. Material and Methods. In a pre-study, sequences of a low-field (0.2 T) scanner (Artoscan, Esaote, Genova, Italy) were optimized for detection of intravenous contrast (0.1 mmol/l Gd-DTPA) in six patients with the autoimmune disease systemic scleroderma. Based on the results of the pre-study, 17 patients with scleroderma (7 sclerotic/10 active inflammatory disease) were scanned using gradient-spoiled 3D GRE sequences (FA 90 °, TR 100 ms, TE 18 ms), which had been established as most sensitive for intravenous contrast. Contrast enhancement of the skin was determined quantitatively by contrast-to-noise ratios (CNR), comparing post- to pre-contrast and dynamic scans (for 6 min, 1 acquisition/min). Patients in the chronic state with sclerodactylia and active inflammation of the hands were considered separately and compared to a control group (n = 10) matched according to age. Results. CNR increase after intravenous contrast was significantly higher in patients with active disease (86 ± 16 % increase) than sclerosing disease (29 ± 3 %, p < 0.05) and the control group (4 ± 2 %, p < 0.05). The dynamic examination showed a significantly slower decrease after the peak rise in the first minute in patients with active disease (CNR 15.4 ± 0.7 to 14.2 ± 1.4) than in those with chronic disease (14.1 ± 0.5 to 11.3 ± 0.9, p < 0.05). Discussion. Capillary leakage is the most likely explanation for the increased enhancement in patients with active scleroderma. Using sequences optimized for contrast detection, disease activity in the course of scleroderma and response to therapy can be determined by MRI in the future.      

Acro-pectoro-renal field defect with contralateral ureteropelvic junction obstruction

Ureteropelvic junction obstruction was noted in a newborn male infant with acro-pectoro-renal field defect. To our knowledge, this association has not previously been reported. Ultrasonography of the urinary tract should be performed on all children with aplasia of the pectoralis major muscle.     

高频电磁场对工人行为功能的影响

采用世界卫生组织推荐的神经行为核心测试组合（ＷＨＯ－ＮＣＴＢ），对高频作业工人４１名（平均工龄１３．９ａ（年）及年龄、性别、文化程度与接触组相匹配的对照组工人３９名（平均工龄１３．３ａ）分别进行了行为功能测试。结果表明高频作业工人部分情感状态得分和某些行为功能得分与对照组相比差异有显著性。长期接触高频电磁场可能引起工人情感状态改变，记忆力减退、注意力分散及心理运动稳定度下降。     

Electrodynamics and ultimate SNR in parallel MR imaging.

The purpose of this article is to elucidate inherent limitations to the performance of parallel MRI. The study focuses on the ultimate signal-to-noise ratio (SNR), which refers to the maximum SNR permitted by the electrodynamics of the signal detection process. Using a spherical model object, it is shown that the behavior of the ultimate SNR imposes distinct limits on the acceleration rate in parallel imaging. For low and moderate acceleration, the ultimate SNR performance is nearly optimal, with geometry factors close to 1. However, for high reduction factors beyond a critical value, the ultimate performance deteriorates rapidly, corresponding to exponential growth of the geometry factor. The transition from optimal to deteriorating performance depends on the electrodynamic characteristics of the detected RF fields. In the near-field regime, i.e., for low B0 and small object size, the critical reduction factor is constant and approximately equal to four for 1D acceleration in the sphere. In the far-field wave regime the critical reduction factor is larger and increases both with B0 and object size. Therefore, it is concluded that parallel techniques hold particular promise for human MR imaging at very high field.     

On information field of clinical diagnosis

“Field” is a universal phenomenon existing in both nature and society, and determines the existence and significance of all materials or information. The man being has always been generating and carrying a large quantity of life information in his whole life. Each piece of life information has an independent information field. The life information field includes such three subfields as bioinformation field, psychoinformation field and psycho-bioinformation field.The clinical diagnosis information field which is a specific information field within the information field of human activities consists of all information concerning man‘s health. Only after we have cognized and ascertained the clinic diagnosis information field, can we accurately utilize its function to serve the human being.     

视场角设置对虚拟环境中目标判断的影响

目的探讨不同视场角参数对虚拟环境中目标判断的影响规律 ,找出最佳视场角参数。方法利用自行研制基于PC平台的虚拟现实 (VR)实验系统 ,选定 45名年龄在 2 3～ 5 8岁被试者并完成大小与角度判断的实验设计。首先进行 30 0人次的预实验 ,确定引起虚拟环境中目标判断差错的视场角及相应观察任务的差别等级 ,然后开始单因素、4水平的完全随机正式实验。结果方差分析表明 ,不同的虚拟环境视场角对目标判断的真实性有显著性影响 ,当视场角为 60°时 ,目标判断的正确率最大。结论利用VR技术进行载人航天器工效设计、操作训练或其它任务的研究时 ,应考虑视场角的作用 ,适合目标大小判断的视场角参数值宜取 60°,以便获得最大的工效     

青光眼病人视野改变与行走速度的相关性研究

目的探讨青光眼病人的视野改变是否影响其行走速度。方法测量 71例青光眼病人的视野和走完一段规定路程所需时间 ,并与相同视力、年龄和性别的正常人进行对比。结果青光眼病人走完规定路程所需时间比正常人多 15 % ;早期青光眼组视野较正常组下降 (P <0 .0 5 ) ,而在行走时间上差异无显著性意义 (P >0 .0 5 ) ;中晚期青光眼组视野较正常组显著下降、行走时间明显增加 (均P <0 .0 1) ,且视野下降程度与所需时间呈显著正相关 (r =0 .78,P <0 .0 1)。结论中晚期青光眼病人的视野缺损可导致行走速度减慢 ,提示对该类病人就诊时要耐心、细致地加以引导 ,在日常生活中给予理解、关怀