Orientation of tendons in the magnetic field and its effect on T2 relaxation times

In vitro studies of spin-spin relaxation times of the protons or hydrogen nuclei which make up the tendon demonstrated significant dependence of T2 on orientation at physiological levels of hydration. T2 varied from approximately 250 mu sec. with the tendon aligned with the magnetic field to 22 msec. at an angle of 55 degrees or 125 degrees and 4 msec. at deviations of +/- 15 degrees from 55 degrees and 125 degrees. 55 degrees and 125 degrees are the so-called "magic angles" at which 3 cos2 theta - 1 = 0. As a result, the signal from human tendons in vivo will depend on their orientation; however, T2 is generally short enough that the signal intensity will approach 0 in MR images regardless of the orientation of the tendons, thereby preventing this phenomenon from being observed in most studies.     

人参的分析——Ⅳ.人参皂甙的高效液相色谱测定

本文报道了人参中六种主要皂甙(Rb₁,Rb₂,Rc,Rd,Re,Rg)的HPLC测定法,用氨基键合相柱,示差折光检测,流动相为甲醇中乙腈—乙二醇—醋酸铵(0.14 mol/L)(30:70:5:10.6),同时还改进了纯化方法,此法快速、重现性好,与薄层比色法比较结果基本一致。     

Computational fluid mechanical evaluation of steady-flow energy losses in cardiac valve prostheses.

A form of the general integral energy conservation equation is applied to the case of steady flow through a rigid control volume bounded by stationary walls and fixed inflow and outflow control surfaces. The total energy loss due to viscous dissipation in the control volume is then defined as the change in mean (pressure + kinetic energy + shear stress energy) quantities between the inflow and outflow surfaces. Computational fluid mechanical modelling can then be used to provide the extensive flow field data necessary to calculate the integral means of the total energy components--not only at the inflow/outflow surfaces, but throughout the control volume via a series of "cutting surfaces" progressing from the inlet to the outlet. This allows interchanges between the various forms of energy to be examined and provides an insight into the mechanisms responsible for these interchanges. Two illustrative examples are presented: laminar flow through a specially designed ball-occluded conduit valve in a long conduit run, and through a caged-ball annulus valve mounted in a ventricle-aorta model. Analysis of the results suggests that a new energy loss parameter be defined--a "valve only" loss, calculated by subtracting the total energy loss for the system with the valve absent, from the total energy loss for the same system with the valve in place. This developed concept of "valve only" energy loss has the potential of standardising the findings of different research groups by removing the arbitrary selection of measurement points from reported results.     

微电极导向颅内同期单侧双靶点毁损术治疗帕金森病

0　引言　近年来 ,以 CT,MRI和微电极导向内侧苍白球(GPi)腹后部毁损术已成为帕金森病外科治疗的主流 .我科自 1997年 10月底在国内首家引进该技术 ,迄今为止已完成手术 10 0 0余例 ,取得了良好的疗效 .但是 ,由于帕金森病临床症状的复杂性和多样性以及毁损脑内不同靶点在改善帕金森病症状方面的不同特点 ,有时仅靠内侧苍白球 (GPi)腹后部毁损术难以全面改善症状 ,尤其对重度静止性震颤和非帕金森病震颤疗效较差 .因此 ,自 1999年 1月开始 ,我们对 10 0例合并重度震颤或其他类型震颤的帕金森病患者进行了同期单侧 GPi腹后部加丘脑 Vim…     

Sporotrichosis masquerading as pyoderma gangrenosum: case report and review of 19 cases of sporotrichosis

We present the case of a 59-year-old woman who had large ulcerations on her right leg that were diagnosed initially as pyoderma gangrenosum and treated with three immunosuppressive agents (cyclosporin, prednisone and azathioprine) for 6 months. Results of a biopsy at 6 months showed numerous cigar-shaped bodies consistent with Sporothrix schenckii; identification was confirmed by tissue culture. A retrospective review was performed for all cases diagnosed as sporotrichosis from tissue culture or biopsy specimens at the Mayo Clinic. Nineteen cases were identified. The present case was the only one in which fungal organisms were visible on histological examination. The present case emphasizes the importance of making a definitive histological diagnosis in unusual ulcer cases or in suspected cases of pyoderma gangrenosum before the initiation of immunosuppressive therapy. The large number of cigar-shaped bodies in the tissue is a rare finding in sporothrix infection and has been reported in only two cases previously.     

显微神经外科手术治疗小脑血管网状细胞瘤32例

1临床资料 2000-03／2003—12共收治小脑血管网状细胞瘤患者32（男21,女11）例,年龄24～59岁,平均38岁．病程1．6～6a,平均1．2a,其中病程1a内共23例,占70％．按类型分为囊肿结节型30例,实质肿块型2例．本组有家族史2例．表现有颅内压增高征27例,共济失调20例,眼球震颤15例,脑神经受损7例．均于术前行颅脑CT和MRI平扫加强化扫描检查,囊肿直径2．5～5．5cm．     

Craniosynostosis: diagnostic value of three-dimensional CT reconstruction

Three-dimensional computed tomography (CT) has an important role in determining the presence and extent of congenital and acquired craniofacial deformities. The authors compared the sensitivity and specificity of three-dimensional CT in the detection and characterization of craniosynostosis with that of planar CT and skull radiography. Eighty-two patients with isolated and syndromal synostoses were imaged with CT and three-dimensional CT, and 42 with skull radiography. Three-dimensional CT scan processing was performed by shaded-surface reconstruction, volumetric, and depth-coded methods. Two trained observers read each scan series in a blinded fashion. Diagnostic utility of the images was determined with receiver operating characteristic analysis. The observers ranked three-dimensional shaded images higher than the other types, with three-dimensional volumetric images second and three-dimensional surface images ranked third. Results of this study demonstrate that three-dimensional shaded-surface reconstruction from CT scans is superior to conventional plain radiographs and CT scans in diagnosing craniosynostosis.