Fat delays emptying but increases forward and backward antral flow as assessed by flow-sensitive magnetic resonance imaging

Flow has been assessed in the gastric antrum using a velocity-sensitive version of the high-speed magnetic resonance imaging technique, echo planar imaging (EPI). Eight healthy volunteers attended fasted on three separate days and consumed 800 mL of either a 5% glucose (0.2 kcal mL-1), 10% glucose (0.4 kcal mL-1) or an isotonic mixed nutrient meal, Fresubin (1 kcal mL-1, 27.2 g fat). Gastric volumes were obtained at 10-min intervals for 1 h. Flow measurements were performed on a single slice through the antropyloric region 5 and 35 min after meal ingestion. Gastric volumes at 45 min were inversely proportional to the calorie density of the meal with (mean +/- SEM) 89 +/- 10%* of the Fresubin, 64 +/- 5%* of the 10% glucose and 41 +/- 5% of the 5% glucose remaining (*P < 0.005 vs 5% glucose). Substantial forward and backward antral flow was observed after all three meals in the initial 5-min imaging period. AT 35 min flow activity was significantly greater after both the high-calorie meals relative to the 5% meal (total number of flow events: Fresubin = 6.6 +/- 1.7,[symbol: see text] 10% glucose = 9.9 +/- 2.2, [symbol: see text] 5% glucose = 2.5 +/- 0.9,[symbol: see text] P < 0.03,[symbol: see text] P < 0.007 vs 5% glucose, n = 8). Peak forward velocities for the initial phase of emptying tended to be greater for the rapidly emptying 5% meal (5.9 +/- 0.8 cm-1) compared with the Fresubin (3.3 +/- 0.6 cm-1, P < 0.069, n = 8) and the 10% glucose (2.9 +/- 1.0 cm-1, P < 0.068, n = 8) meals. In spite of delayed gastric emptying, high-calorie meals were associated with substantial to and fro movements which may be important for meal tritruration and fat emulsification.     

利用EPI Info进行1:R的配比卡方检验

对EPI Info计算1:R的配比卡方检验的方法进行了介绍,并将其计算结果与SPSS、Stata进行比较,简化了1:R的配比卡方检验的计算。     

Multishot EPI-SSFP in the heart.

Refocused steady-state free precession (SSFP), or fast imaging with steady precession (FISP or TrueFISP), has recently proven valuable for cardiac imaging because of its high signal-to-noise ratio (SNR) and excellent blood-myocardium contrast. In this study, various implementations of multiecho SSFP or EPI-SSFP for imaging in the heart are presented. EPI-SSFP has higher scan-time efficiency than single-echo SSFP, as two or more phase-encode lines are acquired per repetition time (TR) at the cost of a modest increase in TR. To minimize TR, a noninterleaved phase-encode order in conjunction with a phased-array ghost elimination (PAGE) technique was employed, removing the need for echo time shifting (ETS). The multishot implementation of EPI-SSFP was used to decrease the breath-hold duration for cine acquisitions or to increase the temporal or spatial resolution for a fixed breath-hold duration. The greatest gain in efficiency was obtained with the use of a three-echo acquisition. Image quality for cardiac cine applications using multishot EPI-SSFP was comparable to that of single-echo SSFP in terms of blood-myocardium contrast and contrast-to-noise ratio (CNR). The PAGE method considerably reduced flow artifacts due to both the inherent ghost suppression and the concomitant reduction in phase-encode blip size. The increased TR of multishot EPI-SSFP led to a reduced specific absorption rate (SAR) for a fixed RF flip angle, and allowed the use of a larger flip angle without increasing the SAR above the FDA-approved limits.     

呼和浩特城区新生儿乙肝疫苗计划免疫效果评价

本文对呼和浩特城区新生儿乙肝疫苗计划免疫效果作了评价。到１９９４年底，城区新生儿乙肝疫苗５年平均报告接种率达９３．７６％；１９９５年采用“批质量保证抽样法”调查，期望接种率达９０％；血清学调查表明，新生儿乙肝疫苗免疫成功率为９６．７７％；１～５岁组儿童（目标人群）抗－ＨＢｓ阳性率达９２．０１％，较计划免疫前５．６７％明显升高（χ２＝３２６．３６，Ｐ＜０．０１）；接种儿童较未接种的同年龄组儿童ＨＢｓＡｇ阳性率下降了５３．９９％，抗－ＨＢｃ阳性率下降了７５．３２％；流行病学效果评价表明，实施计划免疫后的目标人群乙肝发病率（８．３９／１０万）较实施前的同年龄组儿童乙肝发病率（７６．９８／１０万）下降了８９．１０％。     

菏泽市2011年急性弛缓性麻痹监测情况分析

目的评价2011年急性弛缓性麻痹(AFP)病例监测工作质量。方法对AFP病例监测资料进行描述分析。结果 2011年共报告AFP病例41例,15岁以下人群年均报告发病率为3.18/10万,报告后48 h调查率97.56%,合格大便采集率87.80%。41例AFP病例中,5岁以下儿童组所占比例较高,为78.05%;男、女性别比为1.73∶1;大便标本分离到脊髓灰质炎病毒3株,其中I型1株,II型2株,脊髓灰质炎病毒I型经鉴定为疫苗衍生脊髓灰质炎病毒(VDPV)株。结论 AFP病例监测系统各指标均达到要求,监测系统运转正常。未发现脊髓灰质炎野病毒引起的病例。     

综合评估方案设计及黄牌警告机制在免疫规划管理中的应用

目的探索免疫规划综合评估方案及黄牌警告机制在免疫规划管理中的应用及其效果。方法将免疫规划分为行政职能及业务与管理两大类别,拟出评估方案给予合理权重并贯彻实施,分析2001—2005年评估方案的异同并对比工作促进的效果。结果以合理可行的评估方案作技术支撑和整改引导,以黄牌警告机制作行政敦促与推进整改手段,2001—2005年广西免疫规划工作机构得到加强,人员和经费成倍增加。新出生儿童接种率比2001年前增加20％～30％,2006年麻疹发病率为1．85／10万,降至历史最低。结论在贯彻国家规定的目标前提下,结合当地具体情况科学制定免疫规划评估方案,并随着工作重点的不同和效果情况不断调整完善,不断引导,行政手段和业务与管理监管双管齐下,即可遏制工作滑坡势头、步人可持续发展的正轨之效。     

Ultrafast imaging: Principles,pitfalls, solutions,and applications

Ultrafast MRI refers to efficient scan techniques that use a high percentage of the scan time for data acquisition. Often, they are used to achieve short scan duration ranging from sub‐second to several seconds. Alternatively, they may form basic components of longer scans that may be more robust or have higher image quality. Several important applications use ultrafast imaging, including real‐time dynamic imaging, myocardial perfusion imaging, high‐resolution coronary imaging, functional neuroimaging, diffusion imaging, and whole‐body scanning. Over the years, echo‐planar imaging (EPI) and spiral imaging have been the main ultrafast techniques, and they will be the focus of the review. In practice, there are important challenges with these techniques, as it is easy to push imaging speed too far, resulting in images of a nondiagnostic quality. Thus, it is important to understand and balance the trade‐off between speed and image quality. The purpose of this review is to describe how ultrafast imaging works, the potential pitfalls, current solutions to overcome the challenges, and the key applications. J. Magn. Reson. Imaging 2010;32:252–266. © 2010 Wiley‐Liss, Inc.     

Rapid quantitation of magnetization transfer using pulsed off-resonance irradiation and echo planar imaging.

A technique for producing a quantitative measure of magnetization transfer parameters in a clinically feasible time scale is proposed. The combination of pulsed off-resonance irradiation and echo planar imaging has produced an imaging sequence that negates the need for continuous wave irradiation and allows the approach to steady-state conditions to be studied. Data analysis involves the step-by-step numerical solution of the modified Bloch equations to generate a quantitative model of the measured signal intensity based on the relative size of the bound proton pool and the bound proton pool transverse relaxation time. The sequence and model are applied to the study of a series of agar gels of varying concentrations and the results are compared to those from the literature.     

The b matrix in diffusion tensor echo-planar imaging

In diffusion tensor imaging (DTI) an effective diffusion tensor in each voxel is measured by using a set of diffusion-weighted images (DWIs) in which diffusion gradients are applied in a multiplicity of oblique directions. However, to estimate the diffusion tensor accurately, one must account for the effects of all imaging and diffusion gradient pulses on each signal echo, which are embodied in the b matrix. For DTI to be practical clinically, one must also acquire DWIs rapidly and free of motion artifacts, which is now possible with diffusion-weighted echo-planar imaging (DW-EPI). An analytical expression for the b matrix of a general DW-EPI pulse sequence is presented and then validated experimentally by measuring the diffusion tensor in an isotropic phantom whose diffusivity is already known. The b matrix is written in a convenient tabular form as a sum of individual pair-wise contributions arising from gradient pulses applied along parallel and perpendicular directions. While the contributions from readout and phase-encode gradient pulse trains are predicted to have a negligible effect on the echo, the contributions from other imaging and diffusion gradient pulses applied in both parallel and orthogonal directions are shown to be significant in our sequence. In general, one must understand and account for the multiplicity of interactions between gradient pulses and the echo signal to ensure that diffusion tensor imaging is quantitative.     

Point spread function mapping with parallel imaging techniques and high acceleration factors: fast, robust, and flexible method for echo-planar imaging distortion correction.

Echo-planar imaging (EPI) is an ultrafast magnetic resonance (MR) imaging technique prone to geometric distortions. Various correction techniques have been developed to remedy these distortions. Here improvements of the point spread function (PSF) mapping approach are presented, which enable reliable and fully automated distortion correction of echo-planar images at high field strengths. The novel method is fully compatible with EPI acquisitions using parallel imaging. The applicability of parallel imaging to further accelerate PSF acquisition is shown. The possibility of collecting PSF data sets with total acceleration factors higher than the number of coil elements is demonstrated. Additionally, a new approach to visualize and interpret distortions in the context of various imaging and reconstruction methods based on the PSF is proposed. The reliable performance of the PSF mapping technique is demonstrated on phantom and volunteer scans at field strengths of up to 4 T.