电子束X线计算机断层摄影扫描机检测冠状动脉钙化的临床进展

冠状动脉钙化是冠状动脉粥样硬化发展至一定阶段的产物 ,是冠状动脉粥样硬化存在的标志 ;电子束X线计算机断层摄影扫描机是目前定量检测冠状动脉钙化的最佳无创影像方法 ,已成为其它无创检测冠状动脉钙化方法的参考标准 ,所测定的冠状动脉钙化积分与冠状动脉粥样硬化和冠状动脉狭窄之间有着密切关系。临床上应用电子束X线计算机断层摄影扫描机检测冠状动脉钙化作为冠状动脉粥样硬化性心脏病的初步筛选方法。现试就电子束CT检测冠状动脉钙化的临床基础及意义。

乌鲁木齐机场候机厅X线扫描辐射剂量调查与评价

本文报道了乌鲁木齐机场候机厅 X 线扫描机辐射剂量的调查和评价情况,经过对6台X线扫描机现场监测和19名工作人员连续一年受照剂量监测,结果表明这些 X 线扫描机有效能量低、贯穿性不强、利用 X 线扫描技术进行安检所产生微量人工放射线对工作人员和候机厅内环境及公众无有害影响.

主动脉粥样硬化的CT检查体会

主动脉粥样硬化大多发生在40岁以上,多数病灶先出现在腹主动脉,特别是后壁,然后逐渐向上延伸至胸主动脉。本文对1989年8月至1991年8月期间的551例40岁以上腹部CT检查患者进行分析,认为CT能比常规X线较早发现主动脉钙化。此外,CT增强扫描能发现未钙化的粥样硬化斑块或继发性血栓。表现为主动脉内呈弧形或新月状的低密度影。这对本病的早期诊断和治疗起着重要作用。

Tuberculosis versus non-Hodgkin's lymphomas involving small bowel mesentery:Evaluation with contrast-enhanced computed tomography

AIM: To evaluate the specific computed tomography (CT) imaging criteria for differentiating tuberculosis involving the small bowel mesenteric lymph nodes from lymphomas. METHODS: We retrospectively reviewed the anatomic distribution,CT enhancement patterns of lymphoma in 18 patients with mesenteric tuberculosis and 22 with untreated non-Hodgkin’s lymphomas (NHL) involving small bowel mesentery (SBM). Of the 18 patients with tuberculosis,9 had purely mesenteric tuberculous lymphadenopathy (TL),and 9 had mesenteric TL accompanied with tuberculous mesenteritis (TLM). RESULTS: CT showed that tuberculosis and NHL mainly affected lymph nodes in the body and root of SBM. Homogeneously enhanced lymph nodes in the body and root of SBM were found more often in the NHL (P < 0.05). Homogeneously mixed peripheral enhanced lymph nodes in the body of SBM were found more often in mesenteric TL and TLM (P < 0.05). Peripheral enhanced lymph nodes in the root of SBM were found more often in mesenteric TL and TLM (P < 0.01). "Sandwich sign" in the root of SBM was observed more often in NHL (P < 0.05). CONCLUSION: Anatomic lymph node distribution,sandwich sign and specific enhancement patterns of lymphadenopathy in SBM on CT images can be used in differentiating between tuberculosis and untreated NHL involving SBM.

Pneumatosis cystoides intestinalis

Pneumatosis cystoides intestinalis(PCI) is a rare condition that may be associated with a variety of diseases.The presenting clinical picture may be very heterogeneous and represent a challenge for the clinician.In the present paper we describe both a common and an uncommon clinical presentation of PCI and review the pertaining literature.Our cases confirm that,apart from asymptomatic cases,the clinical presentation of PCI may be widely different and suggest that a new onset of stipsis might be the presenting symptom.Diagnosis might be suggested by a simple X-ray of the digestive tract showing a change in the characteristics of the intestinal wall in two-thirds of these patients.However,one third of the patients do not have a suggestive X-ray and require a computed tomography(CT) scan/nuclear magnetic resonance that may reveal a thickened bowel wall containing gas to confirm the diagnosis and distinguish PCI from intraluminal air or submucosal fat.CT also allows the detection of additional findings that may suggest an underlying,potentially worrisome cause of PCI such as bowel wall thickening,altered contrast mucosal enhancement,dilated bowel,soft tissue stranding,ascites and the presence of portal air.Our results also point out that clinicians and endoscopists should be aware of the possible presentations of PCI in order to correctly manage the patients affected with this disease and avoid unnecessary surgeries.The increasing number of colonoscopies performed for colon cancer screening makes PCI more frequently casually encountered and/or provoked,therefore the possible endoscopic appearances of this disease should be well known by endoscopists.

Molten Salt Synthesis of (K_(0.47)Na_(0.47)Li_(0.06))NbO_3 Lead-Free Piezoelectric Ceramics

(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352.

胃肠道间质瘤影像学诊断

目的:探讨胃肠道间质瘤影像学特点及诊断价值。方法:回顾性分析经手术病理证实21例胃肠道间质瘤患者的影像及临床资料。结果:X线钡剂造影:8例显示黏膜变平,撑开见"桥式皱襞",10例表现充盈缺损,2例显示外压性改变,4例见"牛眼征"改变。CT平扫:腔内外肿块密度均匀8例,液平3例,钙化1例。增强扫描肿块均显示强化,12例呈不均匀强化或周边强化。结论:影像检学查有助于胃肠道间质瘤术前诊断。