Reconstruction of three-dimensional anatomical landmark coordinates using video-based stereophotogrammetry

A method is described for reconstructing the 3-dimensional coordinates of anatomical landmarks from multiple video images. This method consists of 2 stages: (1) separate reconstructions of landmark coordinates visible in dorsal and ventral orientations using Direct Linear Transformation (Abdel-Aziz & Karara, 1972), and (2) least-squares alignment of the partial reconstructions using landmarks present in both. The repeatability of the overall reconstructions and of individual landmarks were assessed by performing multiple independent reconstructions of landmark coordinates for 2 canid specimens. Results indicate that the repeatability of interlandmark distances based on stereophotogrammetric reconstructions from standard-resolution video images is comparable to that of caliper measurement, and slightly superior to that of electronic 3-dimensional digitisation. At least 4 images should be available per landmark for optimal repeatability, but additional images allow only a slight increase in repeatability.     

影响计算机X线摄影图像质量因素的临床分析

目的:探讨影响计算机X线摄影(CR)图像质量的因素及优化图像质量的方法.方法:分析2000例不同部位计算机X线摄影成像的技术参数、伪影、IP板使用方式及后处理方法,并与计算机X线摄影的图像质量标准作对照研究,分析影响图像质量的各相关因素.结果:2000例中甲级片1720张,乙级片182张,丙级片98张.乙级与丙级片共280张,其中因摄影技术不当所致141张,伪影引起65张,后处理不当74张.结论:计算机X线摄影图像质量受多种因素影响,合理设置参数及采取各种针对措施能有效提高图像质量.     

Two-dimensional coronary MRA: limitations and artifacts

Our purpose was to assess image quality and interpretation problems of two-dimensional (2D) coronary MR angiograms. The coronary arteries of 27 subjects (12 normal volunteers and 15 patients) were evaluated with 2D coronary MR angiography (MRA). Coronary MRA was performed with a fat-suppressed electrocardiographically gated breath-hold gradient-echo sequence with k-space segmentation using a 1.5-T imager. Image quality throughout the study was occasionally degraded by: image ghosting (22%), ringing (19%), and/or blurring (22%) and incomplete fat-suppression (19%). Intermittent difficulties with breathholding were encountered in 44% of subjects. When limiting the analysis to those images with optimal image quality, interpretative difficulties were sometimes found: misregistration due to inconsistent breathholding (37%); difficulty in distinguishing veins from arteries (37%); obscured anatomy due to overlapping structures (26%); and poor visualization of portions of the left main coronary artery (59%). Two-dimensional coronary MRA studies have image quality and interpretive problems which need to be understood and addressed before routine clinical scanning is initiated.Correspondence to: A. J. Duerinckx     

血液白细胞图象的计算机自动分割方法研究

本文提出了一套血液白细胞图象的计算机自动分割方法。实际测试表明：该方法稳定可靠且有效。单个白细胞检出成功率达９６％，区域分割吻合率平均达９４％，现已将该方法装入作者研制的白细胞自动分类识别ＬＥＵＫ分析系统的分割模块中。     

37例传染性非典型肺炎流行病学调查与讨论

目的了解传染性非典型肺炎(SARS)流行病学的特点,提出相应的预防和控制措施.方法采取现场调查、网上电子病历审查、电话询问等方法.结果37例SARS患者的治愈率为89.2%,病死率8.1%,有接触史患者占37.8%.由于执行了严格的消毒隔离制度,医院内无任何人员感染发病.结论SARS患者在年龄上以青壮年为多,职业类以商业餐饮食人员为多.     

对外伤性骨盆骨折摄影角度的探讨(附30例分析)

目的:探讨骨盆多发性骨折各部位的摄影角度及影像显示的原理及方法,优势与不足以及临床应用价值。方法:首先选择骨髂标本做研究对象进行不同角度的摄影,并选择了最佳摄影角度及方法,进行了30例患者的摄片,均符合临床诊断要求。结果:骨盆多发性骨折的各部位最适宜的摄影角度。骨盆入口位,摄影角度向头侧倾斜25°位;骨盆出口位,摄影角度向足侧倾斜25°位;髂骨及闭孔斜位,一侧抬高25°位,影像显示效果较佳,优于有关报导的摄影角度及方法。结论:对外伤性骨盆多发骨折的患者,各部位摄影角度上述所示,此方法可行,完全符合临床诊断要求。     

Quantification of in-plane motion of the coronary arteries during the cardiac cycle: Implications for acquisition window duration for MR flow quantification

Motion of the coronary arteries during the heart cycle can result in image blurring and inaccurate flow quantification by MR. This condition applies particularly for longer acquisition windows that are typical of breath-hold coronary flow measurements. To determine the sensitivity of the technique to in-plane motion of different coronary arteries, the temporal variation in coronary position was measured in a plane perpendicular to the proximal portion of the vessel. The results indicated the presence of substantial displacement of the coronary arteries within the cardiac cycle, with a magnitude of motion approximately twice as large for the right as for the left coronary arteries. An estimation of the resulting vessel blurring was calculated, showing that the duration of the acquisition window for high spatial resolution coronary flow acquisitions should be less than 25 to 120 msec, depending on the specific coronary artery studied. In addition, these data specify optimal acquisition window placement for high resolution coronary angiography.     

Pulsed magnetization transfer spin-echo MR imaging

Cross relaxation between macromolecular protons and water protons is known to be important in biologic tissue. In magnetic resonance (MR) imaging sequences, selective saturation of the characteristically short T2 macromolecular proton pool can produce contrast called magnetization transfer contrast, based on the cross-relaxation process. Selective saturation can be achieved with continuous wave irradiation several kilohertz off resonance or short, intense 0° pulses on resonance. The authors analyze 0° binomial pulses for T2 selective saturation, present design guidelines, and demonstrate the use of these pulses in spin-echo imaging sequences in healthy volunteers and patients. Using the phenomenologic Bloch equations modified for two-site exchange, the authors derive the analytic expressions for water proton relaxation under periodic pulsed saturation of the macromolecular protons. This relaxation is shown to be monoexpo-nential, with a rate constant dependent on the saturation pulse repetition rate and the individual and cross-relaxation rates.     

基于FT-CMR的心脏功能评估参数对心房颤动冷冻球囊消融患者治疗后复发的预测效能分析

目的 探讨分析基于心脏磁共振特征追踪技术(FT-CMR)的心脏功能评估参数对心房颤动冷冻球囊消融患者治疗后复发的预测效能。方法 选取2019年6月至2020年12月收治的126例预行冷冻球囊消融术的心房颤动患者为研究对象,术前均进行心脏磁共振检查,根据术后6个月内患者有无复发将其分为窦性心律组72例和房颤复发组54例。比较两组患者左心房应变及应变率参数,采用FT-CMR评估患者心脏功能,并进行单因素、多因素logistic回归分析,探讨FT-CMR心脏功能评估参数对心房颤动冷冻球囊消融术后复发的预测价值。结果 房颤复发组患者女性、高血压、糖尿病、非阵发性心房颤动比例显著高于窦性心律组(P<0.05)。房颤复发组患者左心房总应变(Es)、左心房正向应变率峰值(SRs)、左心房被动应变(Ee)、心室舒张早期负向应变率峰值(SRe)、左心房整体纵向应变(PLAS)参数值低于窦性心律组(P<0.05)。Logistic多因素回归分析结果显示,性别(OR=3.511,95%CI:1.036～11.906)、PLAS(OR=1.089,95%CI:1.039～1.141)是心房颤动冷冻...