应用低管电压能谱CT成像降低肾动脉CTA对比剂用量

目的探索低管电压宝石CT能谱成像(GSI)降低肾动脉CTA对比剂用量的应用价值。方法对48例临床怀疑肾血管源性高血压患者行肾动脉CTA,将其随机分为两组:常规组23例,应用常规扫描模式,管电压120kVp,对比剂剂量为1ml/kg体质量;GSI组25例,应用GSI扫描,对比剂剂量为0.5ml/kg体质量。重建GSI组数据,得到101组(40～140keV)单能量图像,从中选出腹主动脉与竖脊肌之间具有最佳CNR的单能量图像;对GSI组最佳单能量图像和常规组图像进行MIP、VR和CPR等后处理,分别在原始图像上测量具有最佳CNR的单能量图像和常规组混合能量图像中双侧肾动脉的CT值、噪声和CNR,并以5分法比较两组重建图像的图像质量,记录并比较两组成像的剂量长度乘积(DLP)。结果 GSI组内,(51±1)keV单能图像具有最佳CNR,与70keV图像相比CNR提高了72.00%(P=0.001)。GSI组中最佳CNR单能量图像的肾动脉的平均CT值(466.45±109.93)HU高于常规组的(317.32±49.93)HU(P<0.001),CNR(14.31±4.70)和主观评分(4.75±0.30)与常规组中混合能量图像[CNR:(17.07±9.60),主观评分:(4.64±0.17)]差异均无统计学意义(P=0.22、0.11)。GSI组的DLP(333.44±19.35)与常规组(340.08±127.06)差异亦无统计学意义(P=0.81)。结论51keV能谱CTA可降低对比剂用量,提高CT值,并维持与常规CTA相同的图像质量,可在具有潜在肾功能损害的患者中推荐使用。     

能谱CT评价实验小型猪肝血管影像

目的 评价能谱CT不同能量成像条件下实验小型猪肝血管影像图像质量,以确定最佳延迟扫描时间和单能图像。方法 对9头小型猪均行常规宝石能谱成像（GSI）扫描,而后注入对比剂,应用智能追踪（Smart Prep）技术对肝脏行动脉期扫描,延迟35、50、70 s分别釆集能谱CT增强图像。测量各延迟时间肝动脉、门静脉、肝静脉、肝实质CT值,计算门静脉与肝实质CT值的差值、肝静脉与肝实质CT值的差值,获得上述差值的峰值,比较不同延迟时间门静脉、肝静脉、肝实质CT值及其差值,确定小型猪门静脉期及静脉期最佳延迟时间。以5 keV为间距,选取40～140 keV的21个单能图像,测量三期图像的SNR、CNR和噪声,确定三期实验小型猪的最佳单能量图像。2名医师在盲法下对重建图像进行主观图像质量评分,一致性评估采用Kappa检验。结果 不同延迟时间门静脉CT值、肝静脉CT值、门静脉与肝实质CT值的差值、肝静脉与肝实质CT值的差值差异均有统计学意义（P均<0.05）,不同延迟时间肝实质CT值差异无统计学意义（P>0.05）。门静脉与肝实质CT值差值的峰值出现时间为延迟50 s,肝静脉与肝实质CT值差值的峰值出现时间为延迟70 s。在65 keV水平,三期图像SNR和CNR均较高,噪声较低。2名医师对三期重建图像的各项评分均≥3分,且均具有中等以上的一致性（Kappa=0.769、0.609、0.727）。结论 动脉期扫描后延迟50 s是能谱CT观察实验小型猪门静脉期的最佳延迟时间,延迟70 s是观察静脉期的最佳延迟时间;65 keV图像是观察实验小型猪肝动脉期、门静脉期及静脉期的最佳单能图像。     

能谱CT单能量技术提高髂静脉MSCTV血管成像质量的研究

目的:探讨能谱CT单能量技术提高髂静脉MSCTV血管成像质量的价值。方法:选择我院2019年1月至2019年12月收治的50例行髂静脉MSCTV血管成像的患者,对患者进行50keV单能量、70keV单能量和混合能量扫描并进行图像重建,分析不同造影条件下成像质量的差异。结果:50 keV单能量成像的CT值、图像噪声、CNR值均高于70 keV单能量成像和混合能量(P0.05)。而70 keV单能量成像的图像噪声低于混合能量,CNR高于混合能量(P0.05),两组CT值无差异(P0.05)。2名影像医师以5分制、双盲法主观评价图像质量,两组医师的50 keV单能量成像评价高于70 keV单能量成像和混合能量(P0.05)。而70 keV单能量成像和混合能量间无差异(P0.05)。结论:利用能谱CT单能量技术在间接法髂静脉MSCTV检查的过程中更有利于提高髂静脉的CT值,提升背景组织和髂静脉之间的对比度,明显改善髂静脉的成像质量,具有较高的临床应用意义,值得进一步推广使用。     

体外实验中宝石CT能谱成像技术血管成像最佳单能量图像的选择

目的 通过体外实验探讨宝石CT能谱成像(GSI)技术血管成像的最佳单能量图像。方法 将非离子型对比剂(碘海醇,300 mgI/ml)用生理盐水稀释成10种不同浓度的溶液置于2 ml硬塑料试管中,浓度依次为1.04、1.17、1.56、2.08、2.34、3.13、4.17、4.69、6.25及9.38 mgI/ml。用猪肉包裹试管后置入水槽中,并加以固定。使用能谱CT进行GSI模式扫描,利用GSI处理/重建平台获得40~70 keV间距为5 keV的7种单能量图像及140 kVp混合能量图像,比较各单能量图像及混合能量图像的CNR、SNR和噪声;并根据管壁边缘锐利度、肌肉及脂肪组织的显示情况及噪声3个方面对图像质量进行主观评价,得出图像质量评分,并进行统计学分析。结果 50 keV(13.28±3.06)及55 keV图像的CNR(14.68±3.75)高于其他单能量图像和混合能量图像(P<0.001),50 keV及55 keV图像间差异无统计学意义(P=0.139)。55 keV图像的SNR(22.18±3.95)高于其他单能量图像和混合能量图像(P<0.001)。与混合能量图像比较,65 keV图像的噪声降低程度(23.08%)优于其他单能量图像(P=0.002)。55 keV的图像质量评分(11.76±0.33)高于其他单能量图像和混合能量图像(χ²=73.05,P<0.001)。结论 本实验中,55 keV图像是能谱CT GSI血管成像的最佳单能量图像,图像质量优于140 kVp混合能量图像。     

双源CT双能量肺动脉成像的单能量图像质量评价

目的 定量评价双源CT双能量肺动脉成像的单能量图像质量。方法 对31例患者行双源CT双能量肺动脉成像,获得低能量(100 kV)、混合能量及各水平单能量图像。测量肺动脉CT值和噪声标准差(SD),计算SNR、CNR,获得SNR和CNR高峰时单能量范围,比较不同水平单能量图像与低能量图像、混合能量图像间肺动脉CT值、SD、SNR及CNR的差异。结果 40~190单能量keV图像中,70~80 keV单能量图像SNR和CNR较高,74 keV图像中二者达峰值。比较70 keV、80 keV和74 keV单能量图像与低能量及混合能量图像差异,70 keV图像与低能量图像肺动脉CT值高于其他各图像,但差异无统计学意义(P均>0.05);低能量图像SD值最高,其次为70 keV图像,80 keV图像SD值最低;各图像CNR值差异无统计学意义(P均>0.05);74 keV和80 keV图像SNR值均高于低能量图像(P均<0.05)。结论 双源CT双能量肺动脉成像中,70~80 keV单能量图像质量与低能及混合能量图像相当,74 keV为本研究条件下的最佳单能量水平。     

CT能谱及灌注一站式成像的兔模型实验

目的初步探讨CT能谱及灌注一站式成像(GSI PERFUSION)的应用价值。方法选取30只被种植VX2肝癌14天的新西兰大白兔行GSI PERFUSION扫描和常规能谱CT扫描,获得CT灌注图像、GSI PERFUSION能谱图像(A组)和常规能谱图像(B组)。测量两组能谱图像的肿瘤、正常肝、竖脊肌、腹主动脉、门静脉的CT值和碘含量(IC)、图像噪声、肿瘤的对比噪声比(CNR)和灌注参数。对肿瘤周边CT强化较明显区域行CD34的免疫组化染色,测定微血管密度(MVD),采用配对样本t检验和Pearson相关性分析进行统计学处理。结果 A组肿瘤组织动脉期CT值和IC均高于B组(P均<0.01),而两组的CNR、噪声、竖脊肌和主动脉/门静脉CT值、正常肝和静脉期瘤灶CT值及IC的差异均无统计学意义(P均>0.05)。两组瘤组织动脉期IC均与血容量(BV)、血流量(BF)、肝动脉分数(HAF)、表面通透性(PS)及MVD呈正相关(P均<0.05),A组中其与平均通过时间(MTT)呈负相关(P<0.05)。两组瘤组织静脉期IC均与BV、BF、PS及MVD呈正相关(P均<0.05)。结论 GSI PERFUSION的能谱图像与常规能谱图像具有相似的图像质量,可用以反映VX2兔肝癌模型肿瘤新生血管情况。     

低剂量对比剂联合宝石能谱CT在正常肝脏中的应用研究

目的 :探讨低剂量对比剂(碘克沙醇270 mg I/m L)联合宝石能谱CT在正常肝脏中的可行性研究。方法 :选择200例正常肝脏入选者,根据不同的扫描模式分为两组,其中100例应用常规扫描模式(常规扫描组),对比剂使用碘海醇(350 mg I/m L);另100例应用GSI扫描模式(GSI扫描组),对比剂使用碘克沙醇(270 mg I/m L)。GSI扫描组数据重建得到70 ke V单能量图像,从中选出肝实质与腰大肌之间具有最佳对比噪声比(CNR)的单能量图像(最佳单能量图像)。对比分析GSI扫描组及常规扫描组图像中肝实质CT值、CNR及DLP。结果:常规扫描组及GSI扫描组动静脉期DLP差异无统计学意义;动静脉期两组CT值差异无统计学意义;动静脉期常规扫描组平均CNR均高于GSI扫描组,且差别具有统计学意义。结论:低剂量对比剂(碘克沙醇270 mg I/m L)联合GSI扫描单能量图像下CT值可以达到与常规扫描组的图像质量标准,但低剂量对比剂(碘克沙醇270 mg I/m L)联合GSI扫描组CNR低于常规扫描组(碘海醇350 mg I/m L)。故碘克沙醇在肝脏实质中的应用有一定的局限性。     

可变螺距技术对头颈部CT血管造影辐射剂量及图像质量影响

目的 探讨可变螺距(vHP)技术对头颈部CT血管造影(CTA)辐射剂量及图像质量的影响。方法 纳入120例接受头颈部CTA检查的患者,并随机分为3组,每组40例。各组以不同参数进行扫描,A组采用常规螺旋扫描,头颈部噪声指数(NI)=5;B组采用vHP技术,头部NI=5,颈部NI=10;C组采用vHP技术,头部NI=5,颈部NI=15;其余扫描参数一致。比较组间辐射剂量及主、客观图像质量评价结果差异。结果 B、C组CT容积剂量指数、剂量长度乘积及有效剂量均低于A组(P均<0.01),且C组低于B组(P均<0.01)。3组CTA图像中主动脉弓及颈总动脉分叉噪声(SD)、信噪比(SNR)及对比噪声比(CNR)差异均有统计学意义(P均<0.05),其中A组SD值最低、而SNR及CNR最高,C组SD值最高、而SNR及CNR最低,B组各值均位于A、C组中间。3组大脑中动脉M1段CT值、SD值、SNR及CNR差异均无统计学意义(P均>0.05)。3组头颈CTA各重建图像均可满足诊断需求,主观评分差异无统计学意义(P=0.241)。结论 vHP技术可在保证图像质量的情况下显著降...     

能谱CT最佳单能量成像提高甲状腺结节图像质量的效果观察

目的:探讨能谱CT最佳单能量成像提高甲状腺结节图像质量的效果。方法:回顾性分析2017年12月至2018年11月我院甲状腺结节患者60例临床资料,术前均行颈部能谱CT双期增强扫描,对比静、动脉期最佳单能量(Opti keV)和70keV单能量的图像,并分析比较其图像噪声(SD)、对比噪声比(CNR)及主观评价。结果:Opti keV成像中静、动脉期图像中微钙化、残圈征、完整强化环及边界显示率均高于70keV成像,差异有统计学意义(P0.05);Opti keV成像中静、动脉期主观评分、SD均高于70keV成像,CNR较低,差异有统计学意义(P0.05)。结论:甲状腺结节患者术前采用能谱CT最佳单能成像可提高图像质量,清晰显示结节细节征象,提高图像的主观评价。     

基于能谱CT单能量技术对颈动脉粥样硬化图像质量的研究

目的：探究能谱CT单能量成像技术对观察颈动脉粥样硬化图像质量的影响，评估最佳单能量水平。方法：回顾性分析本院收治的80例颈动脉粥样硬化患者的资料，均行颈动脉能谱CTA检查，经后处理获得单能量图像（40～140 keV，间隔10 keV）和常规120 kVp-like图像。测量并比较40～70 keV单能量图像和常规组的图像噪声，主动脉弓、双侧颈总动脉、双侧颈内动脉及非钙化斑块和钙化斑块的对比噪声比（Contrast to noise ratio,CNR），同时应用5分法对图像行主观评价；测量斑块短径和狭窄程度，对结果进行统计学分析。结果：随着能级减小，图像噪声、各支血管和斑块的CNR均呈增高趋势，在40 keV时达到最高。各支血管和斑块的CNR在40～70 keV高于常规120 kVp-like组，其中主动脉弓、颈总动脉和非钙化斑块的CNR在40～60 keV水平与常规120 kVp-like组比较有统计学意义，颈内动脉和钙化斑块则在40～50 keV水平（P均<0.05）。40～70 keV单能量图像主观评分均优于常规组，以60 keV单能量图像最佳（P<0.001）。低...     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.     

手转胎头术失败的原因与分娩结局临床分析

目的 探讨手转胎头术失败的原因与分娩结局.方法 选择2008年1月至2010年12月于我院住院分娩的持续性枕横位、枕后位产妇198例,根据行手转胎头术后结果分为成功组126例、失败组72例.比较两组分娩结局,对比分析失败原因.结果 失败组胎儿体质量≥3500 g的发生率[76.4％(55/72)]明显高于成功组[31.7％(40/126)],差异有统计学意义(x2=30.177,P=0.001)、失败组宫缩乏力发生率[58.3％(42/72)]高于成功组[38.1％ (48/126)],差异有统计学意义(x2=7.569,P=0.006)、失败组骨盆临界或轻度狭窄发生率[38.9％ (28/72)]高于成功组[23.8％(30/126)],差异有统计学意义(x2 =5.030,P=0.002)、失败组手转胎头时机不当(宫口开大＜6 cm、胎头位于坐骨棘上及宫口开大8～10 cm、胎头位于坐骨棘下≥2 cm)发生率[61.1％(44/72)]高于成功组[38.9％(49/126)],差异有统计学意义(x2=9.084,P=0.003).失败组母儿并发症(产后出血、产褥病率、胎儿窘迫、新生儿窒息)发生率高于成功组(x2 =9.586,P=0.002、x2=9.334,P=0.002、x2=5.910,P=0.015、x2=5.240,P=0.022)、失败组剖宫产发生率[72.2％(52/72)]明显高于成功组[34.1 ％(43/126),x2=26.641,P=0.001)].结论 手转胎头术能使难产变顺产,降低剖宫产率,减少母儿并发症,但须积极预防、处理导致手转胎头术失败的原因,对矫正失败后继续矫正及试产应慎重.