最佳收缩和舒张期的双源CT冠状动脉影像：自动化选择与全期相固定间隔重建的比较

目的选择双源CT冠状动脉的最佳重建期相，比较全期相固定间隔重建技术与自动化最佳期相选择技术所选择的最佳冠状动脉影像质量。方法对107例病人进行了双源CT冠状动脉血管成像。原始数据经多期相重建和自动化重建优选出最佳收缩期和舒张期影像，以4分法评定系统进行影像质量评价。按照美国心脏病协会的冠状动脉分段原则进行分段。比较上述2种技术最佳收缩期和舒张期的影像质量。结果最佳的影像质量位于R-R间期的70％（平均评分3．11），次之为R-R间期的75％（平均评分3．06）、再之为35％（平均评分为3．03）。自动化期相选择的最佳收缩期影像的平均评分为3．05，舒张期影像质量的平均评分为3．08。2组之间总的冠状动脉影像质量的差别没有统计学意义。按照15个冠状动脉节段计算，除了4段外，其余14个冠状动脉节段对于2种技术显示的冠状动脉影像质量的差别均无统计学意义。结论最佳舒张期和收缩期的影像质量位于R-R间期的70％和35％。自动化最佳收缩期和舒张期重建技术可以获得优良的影像质量，满足临床诊断的需要，但仍需要结合多期相重组技术。     

Best phase软件在双源CT冠状动脉成像选择期相中的应用价值

目的：评价双源CT冠状动脉的最佳期相选择软件（best phase）在选择重建最佳冠状动脉影像期相中的应用价值。方法：收集90例窦性心律病人进行了双源CT冠状动脉血管成像,原始数据多期相重建心动周期的0～95％数据,并由best phase软件自动重建出最佳收缩期和舒张期数据,通过VR重建,以4分法评定系统进行影像质量评价,影像质量的评价限于RCA、LAD和LCX三支血管,比较上述2种技术所选择最佳冠状动脉影像质量。结果：多期相重建最佳的冠状动脉影像质量平均评分3．41,best phase选择的最佳收缩期影像的平均评分为3．25,舒张期影像质量的平均评分为3．40,最佳冠状动脉影像平均评分为3．40,2组之间总的冠状动脉影像质量的差别没有统计学意义。结论：最佳重建期相软件（best phase）技术可以获得优良的影像质量,满足临床诊断的需要,可作为临床常规使用。     

双源CT自动化最佳期相选择的冠状动脉影像质量评价及与心率关系的研究

目的 评价自动化选择的最佳舒张期和收缩期的双源CT(DSCT)冠状动脉影像质量及心率对冠状动脉CT影像质量的影响.资料与方法 107例行双源CT冠状动脉血管成像.原始数据经自动化重组优选出最佳收缩期和舒张期影像,以4分法评定系统进行影像质量评价.按照美国心脏病协会的冠状动脉分段原则进行分段.按照心率将患者分为6组,评价各组之间冠状动脉的影像质量.结果 107例,共纳入分析的血管节段为1297段.最佳收缩期和舒张期分别有1217个(93.8%)和1093个(84.3%)冠状动脉节段可满足影像学评价.所有收缩期的冠状动脉影像质量和心率没有相关性,而舒张期的影像质量与心率呈负相关.当心率>80次/min时,冠状动脉舒张期的影像质量开始明显下降,甚至不能满足影像学评价.结论 利用DSCT最佳收缩期和舒张期自动化选择技术可以获得较为满意的冠状动脉CT影像,可满足临床应用的需要.心率对冠状动脉舒张期的影像质量有较大影响,当心率>80次/min时,应利用最佳收缩期的数据进行影像重组.     

不同心率水平下双源CT冠状动脉成像质量研究

目的:研究不同心率状态下双源CT的冠状动脉成像质量情况及收缩期和舒张期成像质量的差异。方法:345例受试者,男248例,女97例,年龄24~86岁,心率49~133次/分,平均心率74.2±14.4次/分(均未给予药物控制心率),行双源CT冠状动脉CTA扫描,在后处理工作站进行三维重组后,由两名有经验的放射医师对所有受检对象的冠状动脉成像质量进行分段评分(1分~5分)。按受检时心率分为5组,分别统计各组冠状动脉各段的成像质量评分,收缩期和舒张期最佳时相的成像质量评分,以及最佳时相在R-R间期的分布情况。结果:成像成功率为99.9%(3392/3395)。图像质量评分总均值为(4.76±0.57),评分均值与心率呈负相关(r=-0.973,P=0.005)。当心率增高时,收缩期的成像质量和舒张期的成像质量均有下降的趋势,但收缩期下降幅度与舒张期比较明显较缓。当心率<80次/分时,最佳时相多数在舒张期得到,占79.6%(183/230),特别集中于R-R间期的70%左右,占68.3%(157/230),有88.7%(306/345)的受检对象在收缩期和舒张期两期都能得到优良(4分以上)的图像;当心率≥80次/分时,最佳时相多数在收缩期得到,占83.5%(96/115),仅有10.4%(12/345)的受检对象在收缩期和舒张期两期都能得到优良的图像。结论:在排除了心律不齐影响因素的情况下,双源CT在患者处于自然心率状态下其冠状动脉成像成功率接近100%;但心率对冠状动脉成像质量仍有一定影响;当心率<80次/分时大多数可以在收缩期和舒张期双期成像,而心率≥80次/分时一般只能在收缩期成像。     

平均心率、心率波动和心率变异性对双源CT冠状动脉影像质量影响的研究

目的：评价平均心率、心率波动和心率变异性对双源CT冠状动脉影像质量的影响。方法：100例患者进行了双源CT冠状动脉血管成像。原始数据经多期相重建优选出最佳收缩期和舒张期影像,以4分法评定系统进行影像质量评价。利用Pearson相关分析评价平均心率、心率波动和心率变异性对冠状动脉的影像质量的影响,对有相关性者行进一步分析。结果：100例患者,共纳入分析的血管为299支,296支血管可满足影像评价（99％）。平均心率、心率波动和心率变异性对总的冠状动脉影像质量没有影响,仅平均心率对舒张期冠状动脉影像质量有负影响（P〉0．05）,尤其对右冠状动脉的影响更明显,70bpm以上时影像质量即下降,80bpm以上时影像质量甚至难以满足评价。结论：平均心率、心率波动和心率变异性对双源cr冠状动脉总的影像质量没有影响,但平均心率对舒张期冠状动脉的影像质量有负影响,对右冠状动脉的影响更大,当心率大于80bpm时,利用舒张期的数据难以获得RCA满意的影像质量,应该利用最佳收缩期的数据进行影像重组。     

双源CT冠状动脉成像收缩期与舒张期最佳重建相位窗的自动选择

本研究的目的是评价双源CT冠状动脉成像时运动图算法在自动选择最佳重建相位窗时的效果。50例连续病人的影像数据应用运动图算法确定收缩期及舒张期最佳重建相位窗。应用手动法确定最佳重建窗时,扫描数据于R—R间期每隔5％的相位进行一次重建。应用五级法对主要冠状动脉血管的运动伪影进行评分。     

前瞻性心电门控双源CT冠状动脉成像在高心率患者中应用的可行性研究

目的 探讨心率不低于91次/分(bpm)患者回顾性心电门控双源CT(DSCT)冠状动脉成像R-R间期的最佳重建时相,从扫描时相选择的角度分析前瞻性心电门控(简称前门控)应用的可行性.方法 分析232例行回顾性心电门控DSCT冠状动脉成像患者(体质量指数23～25 kg/m2,心率≥91 bpm)的图像,根据扫描过程中患者屏气时心电监控记录到的心率将其分为3组(A～C组),A组83例,心率91～95 bpm,B组68例,心率96～100 bpm,C组81例,心率≥101 bpm.每隔3%重建1个时相,分别由2名医师独立对横断面图像、薄层MIP、CPR、VRT图像质量采用5分法进行综合评估,按照15段分段法,选出每个节段的R-R间期的最佳重建时相及范围.采用Kappa检验,评价2名医师对冠状动脉图像评分的一致性.结果 232例患者中,可评价冠状动脉节段共3343个,其图像最佳重建时相范围集中在81%～61%和51%～31%.3组冠状动脉节段与之相对应的节段数百分比:A组(91～95 bpm,83例的1183个节段)分别为5.49%、94.51%;B组(96-100 bpm,68例986个节段)分别为0.20%、99.80%;C组(≥101 bpm,81例1174个节段)分别为0.17%、99.83%.232例患者的3343个冠状动脉节段中3274个节段(97.94%)最佳重建时相范围集中在以41%为中心的51%～31%R-R间期范围内.2名医师对232例患者的3343个冠状动脉节段图像质量的评分结果得到了较高的一致性(Kappa值=0.883,P<0.05).结论 具有稳定的窦性心律,且屏气时平均心率≥91 bpm患者,冠状动脉节段的最佳重建时相集中于以R-R间期41%为中心的51%～31%,从扫描时相选择的角度考虑,可以对稳定高心率(≥91 bpm)患者行前门控横断面扫描,并且预设41%为曝光时间窗,成功把握较大.     

双源CT在心律失常患者冠状动脉成像中的应用

目的:探讨双源CT在心律失常患者的冠状动脉成像扫描技术及图像后处理中的应用。方法:452例怀疑冠心病的患者行双源CT冠状动脉成像,心律失常患者70例,其中增强扫描过程中平均心率>100次/min的患者共56例,房性早搏(atrial premature beat)6例,室性早搏(ventricular oremature beat)5例,房颤(atrial fibrillation)3例。双源CT自动重建最佳收缩期(best diast)、最佳舒张期(best syst)图像,若图像欠佳者编辑心电图,然后重建图像,把增强扫描图像行多平面重组(MPR)、最大密度投影(MIP)、容积再现技术(VRT)重建、曲面(CPR)重建。将图像质量分为3级,以美国心脏协会(Americanheart association,AHA)推荐的解剖分段方法为标准评价冠状动脉各个节段的图像质量。结果:70例心律失常患者经过心电图编辑后冠状动脉重建的最佳时相均为收缩期。共评价561个节段冠状动脉,其中图像质量1级者占87.9%(493/561),图像质量2级者占7.5%(42/561),图像质量3级者占4.6%(26/561)。结论:双源CT用于心律失常患者的冠状动脉成像可获得满意的冠状动脉各节段图像。     

64层CT冠状动脉成像最佳重建时间窗的探讨

目的 :探讨不同心率及不同重建时相对64层CT冠状动脉血管成像图像质量的影响。方法:收集90例临床疑诊冠心病患者的冠状动脉CTA检查资料。按扫描时平均心率分组,对心动周期的R-R相位30%~90%间期,每间隔5%重建后进行血管分析及评分,获得回顾性心电门控最佳重建时相,并评价不同心率时的图像质量。结果:冠状动脉图像质量随心率增加而降低,两者呈负相关。心率70次/min时,冠状动脉最佳重建时间窗为R-R间期的70%~75%;心率70~79次/min时,冠状动脉最佳重建时相为R-R间期的60%~70%;心率80次/min时,冠状动脉最佳重建时相为R-R间期的40%~50%。左前降支在70%和75%R-R重建时相显示最佳,左回旋支在70%R-R时相显示最佳,而右冠状动脉在50%R-R时相显示最佳。结论 :选择最佳重建时相、合理控制心率能够减轻运动伪影,明显提高冠状动脉成像质量,其中准确选择回顾性心电门控最佳重建时相是保证图像质量、准确诊断的重要因素。     

双源CT全时相间隔重建四维模式对冠状动脉成像质量影响的初步观察

目的 利用双源CT全时相间隔重建并Inspace软件中的四维(4D)模式,评价双源CT对冠状动脉的多时相成像能力,并探讨冠状动脉CT成像(CTA)的质量随时相变化的规律及其形成原因.方法 对50例患者进行双源CT冠状动脉CTA检查,并作10%～100%(间隔10%)全时相重建,然后在后处理工作站上,利用Inspace软件中的4D模式,由2名有经验的放射科医师对各个时相的冠状动脉3支主要分支血管的成像质量进行评级(评分).结果 冠状动脉3支主要血管所有10个时相的平均成像质量评分分别为:右冠状动脉(RCA)1.71分,左前降支(LAD)2.57分,左回旋支(LCX)2.03分(最低为1分,最高为3分).在开始于心脏R-R问期的30%、40%和70%的重组时相窗上,冠状动脉的3支主要分支血管的成像质量平均评分均达到2.0以上.有41例(82%)3支主要血管在收缩期(10%～40%)和舒张期(50%～100%)内同时能找到1个或1个以上的时相其成像质量达到1级(3分).25例(50%)其前降支每一时相的成像质量均达到2级(2分)以上,其中5例(10%)每一时相的成像质量均达到1级.结论 双源CT初步具备了对冠状动脉收缩期和舒张期双期成像的能力,其成像质量存在2个高峰期,1个是收缩中晚期(30%～40%),1个是舒张中期(70%左右);但要达到全时相高质量成像还需进一步提高时间分辨率.     

Multistep phase difference phase contrast imaging

A new technique for multistep phase-contrast image processing is presented. The N-step method consists of simply forming the linear average of the N — 1 adjacent phase-difference signals. It has similar noise reduction properties as other multistep techniques, but the simplicity of the noise variance of the N-step technique allows intuitive insight into phase-difference phase-contrast processing and noise reduction, which can aid in the design of efficient and improved phase-contrast imaging sequences. As well, the computational simplicity of the N-step phase-difference technique compared with any other known multistep technique is advantageous. Like other multistep techniques, it has far more efficient noise reduction properties than simple two-step, multiple average phase-contrast imaging, even when normalized for total scan time. A three-step phase-difference velocity image has 50% less variance than an image acquired with two steps and two scans averaged but is obtained in 25% less scan time. Given its advantages, it should now be the chosen technique for increasing velocity-to-noise and contrast-to-noise ratios in all phase-difference phase-contrast clinical applications.     

Distinct different intra-tumor distribution of FDG between early phase and late phase in mouse fibrosarcoma

An early image of intra-tumor distribution of 14C-labeled fluorodeoxy glucose (14C-FDG) was compared with a late image of 18F-labeled FDG (18F-FDG) using mouse fibrosarcoma. Heterogeneous intra-tumor distribution of 14C-FDG was observed 1 minute post injection of the tracer, whereas relatively homogeneous distribution of 18F-FDG was seen 30 minutes later. 14C-FDG was particularly taken up in the peripheral part of the tumor immediately after the tracer injection. A gradual and significant increase in 18F-FDG accumulation with time was seen in the central part of tumor, which indicated an enhancement of anaerobic glycolysis. An initial uptake of 18F-FDG was also compared with distribution of 14C-iodoantipyrine and 14C-thymidine uptake. Intratumoral distribution of initial uptake of 18F-FDG showed almost the same regional distribution of 14C-iodoantipyrine. A similar distribution of 14C-thymidine as the initial uptake of 18F-FDG was also observed. These results indicated that a high initial FDG uptake area seemed to be highly proliferative. A significant difference in the intratumoral distribution of FDG between early phase and late phase seemed to be related to heterogeneous biological characteristics of tumor cells.     

Semiautomated method for noise reduction and background phase error correction in MR phase velocity data

Background phase distortion and random noise can adversely affect the quality of magnetic resonance (MR) phase velocity measurements. A semiauto-mated method has been developed that substantially reduces both effects. To remove the background phase distortion, the following steps were taken: The time standard deviations of the phase velocity images over a cardiac cycle were calculated. Static regions were identified as those in which the standard deviation was low. A flat surface representing an approximation to the background distortion was fitted to the static regions and subtracted from the phase velocity images to give corrected phase images. Random noise was removed by setting to zero those regions in which the standard deviation was high. The technique is demonstrated with a sample set of data in which the in-plane velocities have been measured in an imaging section showing the left ventricular outflow tract of a human left ventricle. The results are presented in vector and contour form, superimposed on the conventional MR angiographic images.     

Preanalytical phase of sport biochemistry and haematology

Biochemistry and haematology are more and more important and sometimes crucial in sport medicine for diagnosing, controlling and preventing purposes. The analytical process and the global laboratory quality are heavily influenced by the preanalytical phase, including biological material collection, identification, storage and transport of the specimen, preparation for analyses of the specimen through centrifugation, freezing and thawing, aliquoting and sampling. The increasing interest of sport biochemistry should be linked to a knowledge of principal problems and pitfalls in the preanalytical phase of various parameters, commonly used in following training, diet, and performances of athletes, to avoid misinterpretation of data and to improve usefulness of biochemical investigations. We prepared a practical review of preanalytical aspects of principal analyses applied to the athletes. We include the choice of anticoagulant and its limits for haematological tests, the preparation and manipulation of specimens for hormonological investigation, especially for labile molecules, and for cardiac markers, lactate, cytokines, micronutrients, antioxidant molecules. Preanalytical phase of specimens different from blood are also showed, including urine and saliva, and some aspects of preparation of materials to be analyzed with molecular biology technology are treated. Stability of some analytes, when the parameter is fundamental for the clinical usefulness of the results, is supplied. Preparation of the subjects, however, including the possible influence of physical exercise and biological rhythms on the biochemical and haematological parameters, are not listed.     

Susceptibility phase imaging with improved image contrast using moving window phase gradient fitting and minimal filtering

Purpose:

To enhance image contrast in susceptibility phase imaging using a new method of background phase removal.

Materials and Methods:

A background phase removal method is proposed that uses the spatial gradient of the raw phase image to perform a moving window third‐order local polynomial estimation and correction of the raw phase image followed by minimal high pass filtering. The method is demonstrated in simulation, 10 healthy volunteers, and 5 multiple sclerosis patients in comparison to a standard phase filtering approach.

Results:

Compared to standard phase filtering, the new method increased phase contrast with local background tissue in subcortical gray matter, cortical gray matter, and multiple sclerosis lesions by 67% ± 33%, 13% ± 7%, and 48% ± 19%, respectively (95% confidence interval). In addition, the new method removed more phase wraps in areas of rapidly changing background phase.

Conclusion:

Local phase gradient fitting combined with minimal high pass filtering provides better tissue depiction and more accurate phase quantification than standard filtering. J. Magn. Reson. Imaging 2012; 36:1460–1469. © 2012 Wiley Periodicals, Inc.     

原发性肝癌多层面CT双动脉期与门静脉期增强扫描分析

目的：探讨原发性肝癌多层面CT（multi-slices CT,MSCT）双动脉期与门静脉期增强扫描各期强化特征及癌灶的检出率。方法：104例原发性肝癌治疗前行MSCT的平扫与三期扫描（双动脉期与门静脉期扫描）,对比剂用量100 ml,以3 ml/s的速率肘静脉注射,采集时间动脉早期20～22 s,动脉晚期34～37 s,门静脉期60 s。测病灶平扫及各增强期CT值,分析病灶的强化情况及检出情况,以增强各期检出的肿瘤数目为肿瘤灶总数。结果：三期增强扫描共显示470个病灶,34个均匀强化;436个不均匀强化,〈3 cm病灶动脉早期检出117个（56.25%）,动脉晚期检出171个（82.21%）,门静脉期检出137个（65.86%）,≥3 cm的病灶动脉早期检出237个（90.45%）,动脉晚期检出250个（95.41%）,门静脉期检出244个（93.12%）。56个仅在三期增强扫描的一期显示,动脉早期5个,动脉晚期25个,门静脉期26个。结论：动脉晚期的检出率明显高于门静脉期与动脉早期。双动脉期与门静脉期增强扫描有利于提高肝癌检出效率。     

Velocity encoding using both phase and magnitude

Imaging time constitutes a major limitation of phase-contrast (PC) angiography. It is possibly the main disadvantage of PC methods over the time-of-flight (TOF) methods that actually are used clinically. This relatively long imaging time comes from the fact that conventional PC methods require the acquisition of at least four images with different velocity sensitization to reconstruct a single angiogram (1, 2). However, more than one-half of the information gathered through the acquisition of these four images is either redundant or simply discarded. We propose a faster approach to making PC angiograms in which the quantity of data acquired is diminished by as much as a factor 2. This is made possible by encoding velocity information in both the phase and magnitude of the image. Due to the use of extra radiofrequency (RF) and gradient waveforms, decreases in data requirements do not translate in a direct manner into decreases in imaging time. Nevertheless, significant reductions in imaging time are achieved with the present approach.