呼吸运动对PET/CT显像诊断右上腹病灶的影响

目的探讨呼吸运动对PET／CT全身显像诊断右肺底、肝顶病灶的影响。方法回顾分析100例胸部病变患者的^18F-脱氧葡萄糖（FDG）PET／CT显像结果，观察PET、CT及两者融合图像。患者在检查时平静呼吸。观察呼吸运动伪影在不同断面的特点，对右上腹可能出现定位误差的病灶加做常规屏气CT扫描。结果①6例患者因合并胸腔、腹腔积液而未列入统计，其余38．3％（36／94例）的患者PET／CT图像有明显的呼吸运动伪影，矢状面是观察呼吸运动伪影的最佳断面：②呼吸运动致肝顶在矢状面表现为“波浪状”，横断面表现为肝脏边缘模糊，冠状面表现为突入肺底的软组织密度影。③5例患者存在右肺底、肝顶病灶，其定位可能因呼吸运动造成误差。结论呼吸运动伪影是PET／CT显像中常见的现象，对右上腹病灶定位有疑问者应加做常规屏气CT扫描。     

A compact respiratory-triggering device for routine microimaging of laboratory mice

A partial-body plethysmograph was developed for measuring the respiratory flow of anesthetized mice during routine microimaging experiments performed in the close confines of an 89-mm-diameter, vertical-bore magnet. Respiratory flow patterns were used for synchronizing conventional T2-weighted spin-echo imaging with the respiratory cycle, thereby, significantly reducing motion-induced artifacts and increasing observed liver lesion contrast.     

计算机摄影的伪影及其解决办法的探讨

目的 探讨计算机摄影(CR)伪影的产生原因及解决办法.方法 通过分析CR系统各种伪影的特点,从扫描器的机械结构、工作原理、IP板的构造、影像处理、操作者的错误等方面阐述CR伪影的产生原因.结果 伪影大概可分为:前后次影像重叠伪影、IP板扫描中卡片引起的伪影、"流空效应"伪影、灰尘引起的伪影、IP受损引起的伪影、摄影条件过高产生的伪影、散射线引起的伪影、扫描过程中外来光线引起的伪影等方面.结论 正确认识CR伪影产生的原因,并采取相应的预防措施就能尽量防止伪影的产生,大大提高CR的影像质量.     

Recovering EEG brain signals: artifact suppression with wavelet enhanced independent component analysis

Independent component analysis (ICA) has been proven useful for suppression of artifacts in EEG recordings. It involves separation of measured signals into statistically independent components or sources, followed by rejection of those deemed artificial. We show that a "leak" of cerebral activity of interest into components marked as artificial means that one is going to lost that activity. To overcome this problem we propose a novel wavelet enhanced ICA method (wICA) that applies a wavelet thresholding not to the observed raw EEG but to the demixed independent components as an intermediate step. It allows recovering the neural activity present in "artificial" components. Employing semi-simulated and real EEG recordings we quantify the distortions of the cerebral part of EEGs introduced by the ICA and wICA artifact suppressions in the time and frequency domains. In the context of studying cortical circuitry we also evaluate spectral and partial spectral coherences over ICA/wICA-corrected EEGs. Our results suggest that ICA may lead to an underestimation of the neural power spectrum and to an overestimation of the coherence between different cortical sites. wICA artifact suppression preserves both spectral (amplitude) and coherence (phase) characteristics of the underlying neural activity.     

18F-FDG三探头符合线路SPECT图像质量影响因素的临床研究

目的探讨患者在行18F标记的脱氧葡萄糖(18F-FDG)三探头符合线路单光子发射计算机断层成像(SPECT)时各种技术因素对图像质量的影响。方法对838例静脉注射18F-FDG后45 min至1 h行三探头符合线路SPECT检查的患者图像进行回顾性分析,评价患者准备、药物注射、体位摆放、扫描方式及重建、伪影、污染等方面对图像质量所产生的影响。结果由2名有经验的核医学主治医师分析图像。746例图像非常满意,92例图像存在缺陷。存在缺陷的图像中,因患者检查前准备不充分,活动、情绪激动等导致肌肉显影的占16.3%,由药物注射方面引起的占44.6%,体位摆放不当占9.8%,扫描程序、采集方式及图像处理所致占10.9%,尿液或注射点污染、患者移动、膀胱放射性潴留等造成伪影,影响有效观测视野的观察占18.5%。结论18F-FDG符合线路SPECT是肿瘤筛查、诊断及分期的常用核医学检查方法,核医学技术员在日常工作中应尽量避免各种已知可能干扰因素的缺陷对图像质量产生的影响,努力确保显像质量。     

探讨宝石CT能谱成像技术减除脊柱金属植入物伪影的最佳单能量

目的 评价宝石CT能谱成像技术(GSI)单能量成像在减除脊柱金属植入物伪影方面的应用价值,寻求图像质量最佳的单能量成像点。 方法 对19例带有脊柱金属植入物的患者行宝石能谱CT GSI扫描。获得能谱扫描数据后,利用能谱技术,每隔10 keV重建40~140 keV共11组单能量图像,于每组图像中分别选取伪影最重层面(A)和无或少伪影层面(B)的两幅图像行ROICT值和SD值测定,分别记录为CT1、CT2和SD1、SD2,计算伪影指数(AI)。采用配对t检验比较CT值,LSD-t检验比较AI值。 结果 40~140 keV 11组单能量图像中,120 keV单能量图像组,A、B两层面CT值分别为(41.41±9.48)HU和(41.91±7.97)HU(t=－0.21,P>0.05);其他10组两两比较差异均有统计学意义(P均<0.05)。70~140 keV时,两两比较,AI值差异均无统计学意义(P均>0.05);40~60 keV时,与其他能量组两两比较,AI值差异均有统计学意义(P均<0.05)。 结论 能谱CT利用能谱成像技术可有效减除金属植入物的伪影,120 keV为图像质量最佳的单能量成像点,70 keV为伪影减除的分界点。