Isn't a picture still worth a thousand words?

The transmission electron microscope is a valuable diagnostic and research tool that is presently underappreciated. In the area of human immunodeficiency virus research alone, it has provided critical information about viral pathogenesis and opportunistic infections and malignancies. However, because it has not always been used with care, the literature contains misinterpretations, especially as to what is a virus and what is actually a cell organelle, e.g., lysosome and Golgi vesicles. It is important to review the subject periodically to maintain its quality.     

扫描优化对消除高磁场MRI伪影的效果研究

目的 ：探讨消除MRI伪影的各种手段。方法：原始组选择我院MR扫描仪伪影出现比较频繁的检查患者2000例,改进组为经过工程师和技师多方面分析问题后,采取适当抑制伪影措施后的检查患者2000例。结果：原始组伪影例数比例为18.45%,改进组伪影例数比例为4%,后者明显低于前者。结论：通过对二组病例研究,我们了解了伪影产生的原因及比较有效的消除手段。     

Pseudoepidural reverberation artifact: a common ultrasound artifact in fetal cranium

High-intensity reverberation artifacts frequently occur within the fetal cranium during obstetric ultrasound examinations. One hundred ninety-six static ultrasonograms obtained from 100 consecutive obstetric patients were reviewed to determine the incidence, shape, and location of high-intensity reverberation artifacts within the fetal head. Such artifacts occurred in one-third of the fetuses examined. The most common appearance was an arc-shaped artifact that occurred most frequently in the fetal hemicranium farthest from the maternal skin surface. Such an artifact can mimic epidural fluid collections and cause confusion for examiners not familiar with this finding. A discussion of this “pseudoepidural” artifact, its cause, and ways of excluding underlying intracranial pathology is presented.     

Effect of Contrast Concentration,Tube Potential and Reconstruction Kernels on MDCT Evaluation of Coronary Stents: an in Vitro Study

Introduction To evaluate effect of different kVp, reconstruction kernels and contrast concentrations on stent luminal diameter measurements and luminal contrast attenuation values. Methods Two metallic coronary stents (2.75 mm and 3.0 mm) were deployed in silicone tubes and tubes were filled with diluted iodinated contrast (1:20 dilution of Iohexol 350 mg% to achieve an attenuation value of 550 HU at 120 kVp). The tubes were scanned at 80, 100, 120 and 140 kVp. Each scan acquisition was reconstructed using B10f, B25f, B31f, B36f, B41f, B46f, B60f, and B80f kernels. Scans were repeated using 1:35 contrast dilution (350 HU at 120 kVp). Luminal diameter was measured at mid stent level for each stent, in datasets acquired at different kVp, contrast concentrations, and reconstruction kernels. Luminal attenuation values (HU) were measured at the mid stent level and at a distance of 1 cm from the stent entrance within the tube lumen. Results kVp did not have a significant effect on the visualization of stent luminal diameter (P > 0.277). The change in kernel significantly affected the difference in luminal HU values at stent and non-stent levels (P < 0.001), with B46f showing the least difference in HU values. The lower contrast concentration (350 HU) showed substantially less artifactual stent stenosis compared to high contrast concentration (550 HU) (P < 0.001). There was excellent inter-observer agreement for stent luminal diameters and attenuation value measurements (r ²=0.971, P < 0.001). Conclusions For lower spatial resolution kernels, 120 kVp or 140 kVp provides better estimate of stent lumen. Reconstruction kernels and contrast concentration (HU) have significant effect on visualization of in-stent luminal diameter and artifactual stenosis. In clinical practice, B46f kernel and lower contrast enhancement value (∼350 HU) may be optimal for evaluating the stent lumen.     

口腔固定修复金属材料对MRI影像的影响

检测口腔内4种常用固定修复金属材料在磁共振检查时是否产生伪影及伪影的大小,比较不同检查序列对伪影的影响.发现金铂钯合金全冠有轻度伪影;金银钯合金、纯钛全冠有中度伪影;镍铬合金全冠有重度伪影.得出不同金属材料在MRI同一序列成像时对磁共振成像的影响不同;相同金属材料在不同序列成像中的金属伪影大小无明显差别.口腔金属材料产生的伪影与材料类型密切相关,通过合理选择金属材料可得到最佳MRI成像.     

DynaCT在胆道梗阻性疾病的诊断和介入治疗中的应用

目的探讨DynaCT在胆道梗阻性疾病的诊断和介入治疗中的作用。材料和方法对2011年9月至2013年1月共37例胆道梗阻性疾病的患者进行DynaCT检查,获取普通软组织CT图象及三维重建图像。其中男25例,女12例,年龄38～79岁,平均58.5岁。术前扫描进一步明确胆道梗阻的性质、部位及胆管扩张情况,设计预穿刺路径;成功穿刺进入胆管后注入造影剂并行DynaCT扫描显示胆道情况,进一步明确诊断及调整穿刺方向;术后常规扫描评价介入治疗效果。结果 37例患者均成功完成介入治疗,检查中29例造影图像清晰,诊断及引导介入治疗价值大。8例中患者检查图像欠清晰,病变与周围组织密度相差太小3例,病人屏气不好等造成移动伪影3例,造影剂的高密度伪影2例。结论 DynaCT可以一次曝光而获得各种需求图像,可任意角度观察胆管及病变的三维关系,为胆道梗阻患者的诊断与介入治疗提供可靠依据。     

双探头SPECT心肌灌注显像中位移伪影的实验研究

目的 探讨双探头SPECT心肌灌注显像时位移伪影的影像特征和识别方法。方法 将心脏模型置于检查床上，与受检患者的心脏方向一致。在图像采集过程中，模型依次沿相当于患者左右、头尾和前后方向分别在不同起始点、对不同帧数作一定距离的位移。结果位移伪影的共同特点是表现为室壁放射性分布不均匀，“热区”与“冷区”交替出现，在短轴上最早出现，且表现最为明显；伪影进一步发展会在水平长轴和垂直长轴上表现为心尖附近放射性稀疏或缺损，出现与相邻室壁伴行且形态相近的“伴影”。结论位移伪影主要表现为室壁放射性分布不均，“热区”与“冷区”交替出现，在短轴图像上易于早期发现。     

正常人冠状位2D-TOF法MR颅内静脉成像

目的观察冠状位2D-TOF法颅内静脉成像的正常表现和伪影。方法冠状位2D-TOF法颅内静脉成像正常人100例,用工作站的交互式血管成像(IVI)界面,分别在自动生成的三维最大密度投影(3D MIP)图上和原始及重建矢、冠、轴位(S 3P Re)图上,对预定的静脉的显示质量进行分级比较,并注意图像伪影特点和静脉变异。结果在3D MIP和S 3P Re图上,上矢状窦、直窦、大脑大静脉、透明隔静脉、丘纹静脉、大脑内静脉、基底静脉、横窦、乙状窦、枕窦和小脑幕窦100%显示,显示质量高。在S 3P Re图上,Labbe静脉、岩上窦和岩下窦的显示质量优于3D MIP图,两者显示质量差异有统计学意义(P<0.05)。静脉低信号和流动间隙伪影有形态和部位特点。静脉变异常见,如窦汇的不同吻合形式、横窦发育不全、上矢状窦短小、永存镰状窦、永存枕窦、窦内间隔等。结论大多数颅内静脉用冠状位2D-TOF法可良好显示,容易造成误诊的伪影有特点、易辨认,静脉变异常见。     

Influence of Tooth Orientation on the Detection of Vertical Root Fracture in Cone-beam Computed Tomography

Introduction

The purpose of this study was to assess the influence of tooth orientation in relation to the projection plane of the x-rays on the detection of vertical root fracture (VRF) with different filling materials using cone-beam computed tomographic (CBCT) imaging.