母婴互动对婴儿及精神分裂症母亲影响的研究进展

母婴互动作为儿童早期生活中最重要的社会性活动,受到越来越多研究者的关注。精神分裂症患者母婴互动是指患有精神分裂症的母亲与其婴儿间的互动,与传统做法中强制分离不同,目前研究认为,患有精神分裂症的母亲与婴儿间的适当互动不仅能减少母婴分离的时间,而且还能降低母亲的情感压力,提高自我效能。但是,患有精神分裂症的母亲存在母亲敏感性和回应性低、母婴互动协调性和亲密性差等问题。基于此,有必要对精神分裂症患者的母婴互动进行系统的阐述,以了解目前的研究现状,提高公众和研究者们的关注度,为国内开展相关研究提供参考。     

Improved large tip angle parallel transmission pulse design through a perturbation analysis of the bloch equation

Parallel transmission has emerged as an efficient means for implementing multidimensional spatially selective radiofrequency excitation pulses. To date, most theoretical and experimental work on parallel transmission radiofrequency (RF) pulse design is based on the small‐tip‐angle approximation to the Bloch equation. The small‐tip‐angle, while mathematically compact, is not an exact solution and leads to significant errors when large‐tip‐angle pulses are designed. Methods have been proposed to overcome the limitations of the small‐tip‐angle using regularized least‐square optimization or optimal control algorithms. These methods, however, are based on further approximations to the Bloch equation or require the use of general purpose algorithms that do not capitalize fully on the dynamics of the physical model at hand. In this article, a novel algorithm for large‐tip‐angle parallel transmission pulse design is proposed. The algorithm relies on a perturbation analysis of the Bloch equation and it depicts the relationship between the excited magnetization, its deviation from the target pattern and the desired pulses. Simulations and experiments are used to validate the proposed method on a 7T 8‐channel transmit array. The results demonstrate that the perturbation analysis algorithm provides a fast and accurate approach for multidimensional large‐tip‐angle pulse design, especially when large acceleration factors and/or echo‐planar trajectories are used. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Optimal transmit phasing on tissue background suppression in contrast harmonic imaging

Ultrasonic harmonic imaging provides superior image quality than linear imaging and has become an important diagnostic tool in many clinical applications. Nevertheless, the contrast-to-tissue ratio (CTR) in harmonic imaging is generally limited by tissue background signal comprising both the leakage harmonic signal and the tissue harmonic signal. Harmonic leakage generally occurs when a wideband transmit pulse is used for better axial resolution. In addition, generation of tissue harmonic signal during acoustic propagation also decreases the CTR. In this paper, suppression of tissue background signal in harmonic imaging is studied by selecting an optimal phase of the transmit signal to achieve destructive cancellation between the tissue harmonic signal and the leakage harmonic signal. With the optimal suppression phase, our results indicate that the tissue signal can be significantly reduced at second harmonic band, whereas the harmonic amplitude from contrast agents shows negligible change with the selection of transmit phase. Consequently, about 5-dB CTR improvement can be achieved from effective reduction of tissue background amplitude in optimal transmit phasing.     

Parallel RF transmission in MRI

Following the development of parallel imaging, parallel transmission describes the use of multiple RF transmit coils. Parallel transmission can be applied to improve RF excitation, in particular, multidimensional, spatially selective RF excitation. For instance, parallel transmission is able to shorten spatially selective RF pulses in two or three dimensions, or to minimize the occurring SAR. One potential major application might be the compensation of patient-induced B(1) inhomogeneities, particularly at high main fields. This paper provides an overview of selected aspects of this new transmission approach. The basic principles of parallel transmission are discussed, initial experimental proofs are described, and the impact of error propagation on coil design for parallel transmission is outlined.     

A radiofrequency coil to facilitate B₁⁺ shimming and parallel imaging acceleration in three dimensions at 7 T

A 15‐channel transmit–receive (transceive) radiofrequency (RF) coil was developed to image the human brain at 7 T. A hybrid decoupling scheme was implemented that used both capacitive decoupling and the partial geometric overlapping of adjacent coil elements. The decoupling scheme allowed coil elements to be arrayed along all three Cartesian axes; this facilitated shimming of the transmit field, B, and parallel imaging acceleration along the longitudinal direction in addition to the standard transverse directions. Each channel was independently controlled during imaging using a 16‐channel console and a 16 × 1‐kW RF amplifier–matrix. The mean isolation between all combinations of coil elements was 18 ± 7 dB. After B shimming, the standard deviation of the transmit field uniformity was 11% in an axial plane and 32% over the entire brain superior to the mid‐cerebellum. Transmit uniformity was sufficient to acquire fast spin echo images of this region of the brain with a single B shim solution. Signal‐to‐noise ratio (SNR) maps showed higher SNR in the periphery vs center of the brain, and higher SNR in the occipital and temporal lobes vs the frontal lobe. Parallel imaging acceleration in a rostral–caudal oblique plane was demonstrated. The implication of the number of channels in a transmit–receive coil was discussed: it was determined that improvements in SNR and B shimming can be expected when using more than 15 independently controlled transmit–receive channels. Copyright © 2010 John Wiley & Sons, Ltd.     

7-T (1) H MRS with adiabatic refocusing at short TE using radiofrequency focusing with a dual-channel volume transmit coil

In vivo MRS of the human brain at ultrahigh field allows for the identification of a large number of metabolites at higher spatial resolutions than currently possible in clinical practice. However, the in vivo localization of single‐voxel spectroscopy has been shown to be challenging at ultrahigh field because of the low bandwidth of refocusing radiofrequency (RF) pulses. Thus far, the proposed methods for localized MRS at 7 T suffer from long TE, inherent signal loss and/or a large chemical shift displacement artifact that causes a spatial displacement between resonances, and results in a decreased efficiency in editing sequences. In this work, we show that, by driving a standard volume coil with two RF amplifiers, focusing the B field in a certain location and using high‐bandwidth adiabatic refocusing pulses, a semi‐LASER (semi‐localized by adiabatic selective refocusing) localization is feasible at short TE in the human brain with full signal acquisition and a low chemical shift displacement artifact at 7 T. Copyright © 2011 John Wiley & Sons, Ltd.     

针灸配合心理疏导治疗慢性传输型便秘34例

[目的]观察针灸配合心理疏导治疗慢传输型便秘的临床疗效。[方法]34例采用针灸、配合心理疏导治疗。[结果]34例中,痊愈14例(41.2%),明显好转11例,好转4例,总有效率为85.3%。[结论]慢传输型便秘针灸治疗操作简便、有效,心理疏导能有效辅助治疗便秘。二者配合,达到增效目的。