adaptive fourier threshold filtering: A method to reduce noise and incoherent artifacts in high resolution cardiac images

We introduce an image processing method which reduces white noise and random artifacts in sets of high resolution, time resolved images. At each pixel, the processing consists of: (1) the isolation of a time intensity curve (TIC), (2) Fourier transformation of each TIC, (3) application of a threshold to remove low intensity coefficients, (4) inverse transformation to generate noise reduced TICS which are recombined to form images with improved signal-to-noise ratio (SNR). Noise filtering by Fourier thresholding is demonstrated on a set of cardiac images, resulting in a reduction of the noise energy by approximately 90%.     

不同形状界面对界面射流的影响──彩色多普勒与激光荧光染料方法的研究

本文通过应用彩色多普勒及激光荧光染料显示射流方法研究了不同形状界面对射流的影响。结果表明对照组及平坦界面射流时，彩色多普勒与激光荧光染料两种方法无显著差异；在弯曲界面条件下，彩色多普勒射流小于激光荧光染料射流（Ｐ＜０．０１～０．０００１）。彩色多普勒研究表明不同形状界面射流大小分别与每搏容量相关好（ｒ＝０．８３～０．９９），但射流大小明显不同。凹形界面射流面积最小，平坦及凸形界面射流面积也小于对照组。研究提示不同形状界面可以导致界面射流不同程度地减小，并且彩色多普勒也不易对弯曲界面的射流完全成像。在临床上应用彩色多普勒对返流定量时，需考虑上述影响。     

Primary diffuse leptomeningeal gliomatosis followed with serial magnetic resonance images

We report a case of primary diffuse leptomeningeal gliomatosis (PDLG) followed up with serial magnetic resonance images (MRI). A 45‐year‐old man manifested with bilateral abducens nerve palsy and meningisms. Repeated MRI revealed diffuse leptomeningeal enhancement throughout the central nervous system without intra‐axial mass accompanied with the dilatation of ventricles and focally enlarged cerebral sulci. Brain biopsies showed a leptomeningeal gliomatosis. The MRI findings described here would contribute to the diagnosis of PDLG among other common diseases diffusely spreading along the leptomeningeal structures.     

TIA磁共振弥散加权成像异常的相关因素分析

目的探讨短暂性脑缺血发作(TIA)磁共振弥散加权成像(DWI)异常的相关因素。方法对2006年1月～2006年12月临床诊断为TIA的住院患者45例进行回顾性分析,比较DWI异常组和正常组的临床特征,并采用Logistic回归分析判定与DWI异常有关的独立因素。结果DWI异常14例(31%);多元回归分析提示TIA症状持续时间≥1h(OR=2.5,95%CI:1.3～8.6)和症状表现为失语伴运动障碍(OR=8.9,95%CI:2.1～36.5)与DWI异常独立相关。结论TIA患者DWI异常与TIA症状持续时间和症状表现为失语伴运动障碍有关。     

Image size magnification and power and dilation factors for optical instruments in general

Traditional treatments of spectacle magnification for distant objects consider only stigmatic spectacle lenses and they compare the retinal image size in a refractively fully compensated eye with the image size in the uncompensated eye. Spectacle magnification is expressed as a product of two factors, the power and shape factors of the lens. The power factor depends on the position of the entrance pupil of the eye. For an eye with an astigmatic cornea, however, the position of the entrance pupil is not well defined. Thus, the traditional approach to spectacle magnification does not generalize properly to allow for astigmatism. Within the constraints of linear optics and subject to the restriction that the eye's iris remains the aperture stop, this paper provides a complete, unified and exact treatment for optical instruments in general. It compares retinal image size in a generalized sense (including image shape and orientation) for any instrument in front of an eye with that of the eye alone irrespective of whether the instrument compensates or not. The approach does not make use of the concept of the entrance pupil at all and it allows for astigmatism and for non-alignment of refracting elements in the instrument and in the eye. The concept of spectacle magnification generalizes to the concept of instrument size magnification. Instrument size magnification can be expressed as the product of two matrix factors one of which can be interpreted as a power factor (as back-vertex power) and the other factor for which the name dilation factor is more appropriate in general. The general treatment is then applied to a number of special cases including afocal instruments, spectacle lenses (including obliquely crossing thick bitoric lenses), contact lenses, stigmatic systems and stigmatic eyes. In the case of spectacle lenses, the dilation factor reduces to the usual shape factor.     

关于引进双源CT的可行性分析

本文就双源CT的市场需求、特点和用途进行了详细分析,为医院引进双源CT提供参考。     

感染日本血吸虫的家兔治疗前后肝纤维化动态观察

感染日本血吸虫的家兔治疗前后肝纤维化Ｂ超声像图模型、血清ＭＡＯ水平及病理学结果表明，血吸虫引起的肝纤维化变化过程与血清ＭＡＯ水平升降趋势趋向一致，均在１８周达到高峰。解剖与病理学检查结果基本相符，血吸虫性肝纤维化形成后，只要及时给予杀虫治疗，肝纤维化部分可发生逆转。     

Assessment of tardive dyskinesia by means of digital image processing

A wireless device for the assessment of tardive dyskinesia by means of digital image processing is presented. Four skin-cream dots placed around the subjects' mouth are recorded by a video camera. The image is passed to a framegrabber with a signal processor, where it is converted from analogue to digital. A fast spot-detecting algorithm implemented on the signal processor tracks the dots and passes the information to a personal computer, where a Fourier transformation is performed to calculate the frequency spectrum of the movements. The device provided detailed information on the magnitude and on the frequencies of the movements. Data from a longitudinal investigation suggest a higher sensitivity and reliability than conventional rating scales to detect and evaluate abnormal perioral movements. The device might be useful for the early detection, for the longitudinal assessment (p.e. clinical trials) and in some cases for the differential diagnosis of tardive dyskinesia, thus providing a tool for both research and clinical purposes.     

核医学影像设备的发展与临床应用

γ相机和SPECT只能进行常规单光子显像，PET和双探头SPECT符合显像系统既能进行单光子显像，又能进行正电子符合显像，PET／CT系统的出现不仅提供高质量的衰减校正图像，保证了正电子显像校正数据的可靠性，而且能进行同机图像融合，提高了影像定位诊断的准确性。本文简要介绍了核医学影像设备发展历程，PET和PET／CT的原理以及在临床的应用。