不同扫描方式对提高超高龄患者肺部CT图像质量的应用研究

目的:探讨不同扫描方式对超高龄患者肺部CT图像质量的影响。方法:选取行肺部检查的超高龄患者(≥75岁)100例,采用不同扫描方向和呼吸控制方式随机分为4组,每组25例,A组采用鼻式呼吸行足向头侧扫描,B组采用鼻式呼吸行头向足侧扫描,C组采用呼吸控制行头向足侧扫描,D组采用呼吸控制行足向头侧扫描。将采集的图像按不同的肺部分区进行质量评分和伪影分级统计。结果:A组图像质量评分最高,B组评分最低,4组中、下肺区的图像质量评分和总评分的差异均具有统计学意义(均P0.05)。组间两两比较,A组与B组、B组与C组、B组与D组的中、下肺区图像质量评分和总评分比较,差异均有统计学意义(均P0.05)。A组重度伪影发生频率最低,B组最高,A组与B组的无伪影和重度伪影发生频率差异均具有统计学意义(均P0.05),A组与C、D组的重度伪影发生频率差异均有统计学意义(均P0.05)。结论:采用鼻式呼吸行足向头侧扫描可减少超高龄患者肺部CT检查的呼吸伪影,提高图像质量,值得临床推广应用。     

16层螺旋CT低剂量扫描在女性骨盆中的应用

目的 评价16层螺旋CT低剂量扫描在女性骨盆中的应用。方法 30例志愿者用16层螺旋CT行女性骨盆扫描，分别采用低剂量扫描（CareDose）和传统方法扫描，将两组女性骨盆图像按各影像颗粒均匀性、解剖结构细节、界面清晰度和有无伪影等评定图像质量。同样对两组的CT检查辐射剂量进行对照研究。结果 两组扫描方法对女性骨盆图像质量的显示差异无统计学意义；剂量扫描与传统扫描相比，辐射剂量大大降低（P〈0．01）。结论 16层螺旋CT低剂量扫描在女性骨盆图像质量不下降的同时，可以较传统CT扫描减少受检者的辐射剂量。     

消除非机器伪影提高CT图像质量

随着科技的发展，CT机的发展也经历了几个阶段，尤其是多排螺旋CT机的问世使得CT机应用日益广泛。但是在CT扫描成像过程中，常有不同程度的伪影，在工作中应认识伪影特征、原因，采用适当方法消除，提高图像质量，从而提高诊断正确率。伪影分为机器伪影和非机器伪影两类。机器伪影是CT机本身故障引起的伪影，一般根据ER-     

MSCT扫描方式对图像后处理质量影响的研究

目的：探讨MSCT扫描方式对图像后处理质量的影响。方法：对我院2009年8月～2010年8月间因头面部外伤致骨折需要作CT三维重建的伤者200例,其中男性108例、女性92例,年龄29～65岁,随机平分为2组,采用GE64层螺旋CT以相同的扫描参数及扫描范围,分别对两组病例进行轴向、螺旋扫描,扫描图像传至AW4.3工作站进行图像后处理。辐射剂量在扫描后机器自动记录的信息中获得CT剂量指数（CTDIvol）、剂量长度乘积（DLP）等信息,并直接比较两种扫描方式辐射剂量的大小。图像质量由三名有丰富经验的主管、副主任技师对原始图像、VR及MPR图像进行颅脑组织结构及骨折线清晰度的大小、伪影的有无及大小、有无扫描间隔线等方面进行评价。结果：轴向扫描较螺旋扫描的CTDIvol及DLP更低。轴向扫描原始图像上颅脑及周围结构清晰度较螺旋扫描大,并且均无明显伪影,而螺旋扫描有明显伪影。轴向扫描VR图像均有扫描间隔线,但并不影响对骨折的观察,而螺旋扫描没有;轴向扫描VR图像上对颅骨骨折线的观察与螺旋扫描之间没有明显差别;轴向扫描所有VR图像上没有伪影,而螺旋扫描却有。轴向扫描MPR图像上均有扫描间隔线,也不影响对骨折及其他结构的观察,而螺旋扫描没有;轴向扫描MPR图像上没有明显伪影,而螺旋扫描却有并影响对脑组织及其周围结构的观察。结论：在扫描参数相同的条件下,MSCT轴向扫描的辐射剂量更低而图像后处理质量更高。     

单次对比增强双源CT双能肺灌注成像扫描及重组参数的优化

目的探讨不同扫描技术对双源CT(DSCT)双能肺灌注成像的影响,优化扫描和重组参数。资料与方法在相同对比剂浓度、负荷和注射流率前提下,60例患者随机分为5组,组1～3:利用人工智能触发扫描trigger技术,将感兴趣区设在肺动脉主干,当CT值达到100 HU时,再分别延迟3 s、6 s、9 s后扫描自动开始,其余扫描参数均为探测器准直14 mm×1.2 mm,球管旋转时间为0.5 s,螺距为0.5,重组层厚1.5 mm,间隔1.0 mm,足头方向。组4:头足方向,其他扫描参数同组2;组5:重组层厚1.5 mm,间隔1.5 mm,其他扫描参数同组2。测量升主动脉、肺动脉主干以及上腔静脉的CT值,并观察肺动脉分支显示级别和上腔静脉线束硬化伪影出现情况,评价DSCT双能肺灌注及肺动脉CT血管造影(CTA)的图像质量。结果与其他组相比,组2肺动脉强化值较高,上腔静脉强化值较低且线束硬化伪影较少,肺动脉5级分支显示清晰,同时具备优良的双能肺灌注和肺动脉图像质量,差别有统计学意义(P<0.05)。结论在相同对比剂浓度、负荷和注射流率前提下,组2的扫描方案可获得满意的肺双能灌注成像及肺动脉CTA的图像质量,结合临床实用情况...     

CT能谱成像用于减少锁骨下对比剂伪影的临床研究

目的:寻找CT能谱成像的最佳能量点以减少肺部增强CT扫描锁骨下腋静脉和锁骨下静脉对比剂伪影,并改善图像质量。方法:共66名病人接受能谱CT扫描。一次能谱成像获得12组图像:140kVp混合能量图像和11组单能量图像(40～140keV)。比较混合能量和单能量图像在肺部增强CT动脉期的伪影区噪声、信噪比(SNR)、对比噪声比(CNR)和平均线束硬化伪影指数(BHAs)。BHAs是感兴趣区和背景区噪声平方差的平方根。结果:与常规混合能量组相比,120keV可最大程度地减少硬化伪影(P=0.000),同时SNR、CNR明显减小,导致软组织对比度明显减低。70keV可以减小硬化伪影(P=0.042),且SNR、CNR最高,优于混合能量图像和其他单能量图像,而伪影区噪声减低,图像质量最好。结论:在肺部增强扫描中,120keV去除对比剂硬化伪影的能力优于混合能量图像及其他单能量图像,但是组织对比度较差,可以结合70keV图像共同进行诊断。     

多层螺旋CT胸部增强扫描的优化选择

目的：探讨多层螺旋CT胸部增强扫描最佳的对比剂注射流率和扫描方式。方法：80例CT胸部增强扫描随机分为4组，每组20例。组1、2、3、4注射流率分别为3.5ml/s、3.5ml/s、4.0ml/s、4.0ml/s；组1、3从肺尖向膈肌扫描；组2、4为膈肌向肺尖扫描。对比剂300mg I/ml，总量80ml。扫描延迟18s，平均扫描时间11.4s。扫描范围平均200mm。评价主动脉和肺动脉增强CT值、上腔静脉伪影和患不适感。结果：各组大血管强化CT值均数在250HU以上。3.5ml/s组和4ml/s，以及2种不同的扫描方向，其大血管总体增强程度均无显性差异（P＞0.05)。上腔静脉伪影以从膈肌向肺尖扫描为少（P＜0.05)。对比剂注射流率增加，伪影亦增加（P＜0.05)。组1和组2，患均无不良反应；组3和组4，各有1例患诉注射局部不适感。结论：以3.5ml/s注射流率从膈肌向肺尖部扫描，是多排螺旋CT胸部增强扫描较好的扫描方式。     

回顾性电影法心电门控多层螺旋CT与常规HRCT肺部扫描的对照研究

目的 评价回顾性电影法心电门控多层螺旋CT(ECG-MSCT)肺部扫描的作用。资料与方法 选取2000年7月～2001年6月间行肺部CT检查者50例,男36例,女14例。其中最高心率为88次/min,最低心率为58次/min,平均72.8±12次/min。采用GE Light Speed多层螺旋CT机和SUN图像工作站完成所有病例的检查。首先行常规HRCT扫描,随后只对需要作对比的层面进行同部位ECG-MSCT扫描,并以产生搏动性伪影最明显处的肺实质图像为主要观察对象。将心电门控扫描图像转至工作站进行图像后处理,由3位放射科医师分别进行盲法阅片作同层面图像质量比较。对所有图像质量采用评分方法进行评价。结果 通过同层ECG-MSCT图像和常规HRCT图像伪影评分的比较,发现两者有显著性差异(P<0.001)。心脏搏动双重伪影出现率有明显减少(P<0.05);双轨征出现率也显著减少(P<0.05);星状伪影消除率为60％,较常规HRCT有明显改善(P<0.01)。采用ECG-MSCT和常规HRCT扫描,对消除呼吸运动伪影方面,两者无显著性差异(P>0.05)。结论 ECG-MSCT扫描方法简便易行,可明显消除心脏搏动伪影、双轨征及常见的星状伪影,从而提高了图像的诊断质量,减少由于伪影而造成的误诊。     

64排螺旋CT冠状动脉成像的图像质量影响因素分析

目的：观察影响64排螺旋CT冠状动脉成像质量的因素。方法选择75例疑似冠心病患者行64排螺旋CT冠状动脉检查,分析影响其成像质量的因素。结果心率及屏气等方面是影响图像质量的重要因素。结论64排螺旋CT冠状动脉成像可评估率良好,然而受到患者或扫描因素的影响往往会产生伪影,分析伪影成因不仅可改善图像质量,还有利于避免出现假阳性结果。     

胸部螺旋CT扫描的最佳造影剂浓度及延时

目的：探讨纵隔血管螺旋ＣＴ扫描的最佳延迟时间及造影剂含碘浓度。材料与方法，本文搜集１２０例胸部螺旋ＣＴ增强扫描资料，４０例为回顾性研究组，主要研究强化血管出现伪影时的ＣＴ值，例如上腔静脉区等，另８０例为前瞻性研究组，其中又分Ｓｍａｒｔｐｒｅｐ组（研究最佳延迟时间）及造影剂浓度组（确定纵隔血增强之最合适的造影剂浓度），图像质量的评判标准为血管强化充分又为伪影存在。结果，头臂静脉，上腔静脉，升主动脉和     

Reduced computed tomography radiation dose in HIV-related pneumonia: effect on diagnostic image quality

PURPOSE: The objective of this study was to compare the diagnostic quality of low-dose computed tomography (CT) with that of standard-dose chest CT in the diagnosis of infectious lung diseases. MATERIALS AND METHODS: Thirty chest CT scans [high-resolution computed tomography (HRCT), 15; spiral CT, 15] were performed in HIV-positive patients with an infectious lung disease. Two additional slices were obtained at two lower exposures (HRCT, 120 kV/70 mAs and 120 kV/50 mAs; spiral CT, 100 kV/56 mAs and 100 kV/40 mAs) after chest routine CT. Observers compared the quality of the images obtained at different parameters and image noise. Objective evaluation of image noise was also made. RESULTS: Diagnostic image quality was excellent in 93% of the low-dose HRCT scans and in 86% of the low-dose spiral CT scans, rates that are always acceptable in any case. Significant differences were found in noise levels between the low-dose and reference scans; however, artifacts did not compromise detection of abnormalities. In HRCT, a mean reduction of 77% from the standard technique to the low-dose scan is possible in total and in lung effective doses. In spiral CT, this reduction is lower at 71%. These values can reach a further reduction with ultra-low-dose imaging (84% in HRCT and 80% in spiral CT). CONCLUSIONS: Chest CT image quality appears to be adequate to evaluate pulmonary infectious diseases, even with an effective reduction in radiation dose. Standard-dose CT with a higher patient effective dose may be appropriate for selected cases.     

Image quality of spiral CT versus conventional CT in routine brain imaging

Objective: Aim of the study was to compare image quality of spiral (helical) versus conventional (sequential) routine brain scans obtained on a spiral CT scanner of the latest generation. Materials and methods: In a prospective study 60 patients scheduled for cranial CT were examined in spiral (27 cases) or conventional technique (33 cases) after randomization. Two blinded observers rated artifacts, gray–white-matter contrast and overall image quality. Results: No significant differences in artifacts were detected. Concerning gray–white-matter contrast and overall image quality, none or small differences in favour of conventional scans were found depending on the observer. Conclusion: On a modern scanner image quality of spiral brain scans in adults is nowadays comparable to or only slightly less than that of conventional scans. On such a machine, spiral mode can be recommended if, for example, rapid scanning or high-quality secondary reconstructions are needed.     

多层螺旋CT肺部低剂量扫描的应用价值

目的：探讨多层螺旋CT肺部低剂量扫描的应用价值。材料和方法：对77例体检者行多层螺旋CT常规剂量肺部扫描后再行低剂量扫描,对照分析其质量。结果：77例受检者中,两种检查方法均发现异常35例,无异常42例,对病变征象和正常结构的显示率均为45%和55%,图像质量均为优。低剂量扫描较常规剂量扫描的X线剂量少。结论：肺部多层螺旋CT低剂量扫描能提供与常规剂量扫描相近的诊断与鉴别诊断信息,适用于大规模体检及高危人群普查。     

Spiral CT vs incremental CT: Is spiral CT superior in imaging of the brain?

The aim of this study was to evaluate image quality of spiral CT of the brain as compared with incremental CT using identical scanning parameters. Incremental or spiral cranial CT was performed on 46 consecutive, randomized patients with non-traumatic disease of the brain on a Siemens (Erlangen, Germany) Somatom Plus 4. Evaluation was done in a randomized blinded way by two experienced radiologists. Different anatomical structures, image noise, and artifacts were scaled 1 (bad) to 4 (very good). Statistical analysis was done using the F-test of variance for partial sums of squares as well as Student's t-test. Incremental CT was superior to spiral CT for evaluation of the internal capsule, supratentorial artifacts, gray/white matter differentiation, and image noise. No statistically significant differences were seen for evaluation of the pons, infratentorial artifacts, and eye muscles. With identical scanning parameters incremental CT is superior to spiral CT in the assessment of small, complex structures in a low-contrast setting. No differences are seen for larger structures or small structures in a medium-contrast range. Artifacts localized close to the skull in spiral CT can easily mimic hemorrhage in traumatized patients. Spiral CT should therefore only be used for CT angiography and if 3D reconstructions are needed. Received 19 June 1997; Accepted 6 August 1997     

Motion artifacts in cardiac CT. The Novacor left ventricular assist device and its implications for clinical imaging

PURPOSE: Cardiovascular applications of CT are primarily limited by temporal resolution of the scanner. Recent development in scanner technology has greatly increased temporal resolution. We here describe a standardized method of assessing temporal properties of various CT techniques. MATERIAL AND METHODS: The Novacor left ventricular assist device was mounted in a water-filled circulation phantom and scanned at different pump rates with a spiral CT unit and an electron beam unit. We also evaluated the use of ECG-triggered subsecond scanning on a spiral CT unit. RESULTS: Using the fastest conventional scanning protocol, severe motion artifacts occurred. These artifacts could not be reproduced from image to image, even if the pump rate was adjusted to scan rate (l/s). Electron beam tomography (EBT) reproducibly yielded few artifacts at 100 ms and practically no artifacts at 50 ms scanning time. Even without ECG-triggering, pump motion could be reproduced as a cine-cycle. With the ECG-triggered partial scanning CT technique, limited motion artifacts could be reproduced during diastole at a heart rate of 70-80 beats/min. CONCLUSION: The Novacor ventricular assist device may serve as a benchmark test in the evaluation of new scanning techniques for cardiovascular CT. While EBT presently remains the only CT technique to freeze cardiac motion throughout its cycle, ECG-triggered subsecond scans may, under certain conditions, capture cardiac anatomy in diastole.     

CT反向扫描对消除慢阻肺患者呼吸运动伪影的应用价值

目的 探讨CT反向扫描对消除慢阻肺(COPD)患者在CT扫描中呼吸运动伪影的价值. 方法 随机抽取40例COPD志愿受检者,采用GR-Helical肺扫描技术进行顺向和反向扫描,所获得的图像由3名高年资影像诊断医师进行双盲质量评价. 结果 40例病例中,出现呼吸运动伪影17例,其中70.59%居下肺野,64.7%好发于60岁以上人群.顺向扫描伪影率为35%,经反向扫描伪影率降低到7.5%,下肺野未见明显伪影,图像质量提高了27.5%,2种扫描方法在统计学上具有显著性差异(P<0.05 ). 结论 CT反向扫描可有效抑制和消除下肺野呼吸运动伪影的发生,是慢阻肺患者的首选扫描技术.     

腮腺CT扫描方式的辐射量评估

目的:探讨腮腺CT检查时步进式扫描与螺旋式扫描的辐射剂量比,为选择合适的扫描方式提供参数.方法:将30例腮腺患者随机分成2组,17例行步进式扫描,13例行螺旋式扫描,分别记录2种扫描A-式的CTDIw、DLP、总毫安秒,观察两种扫描方式的图像质量及阳性检出率,并对数据进行统计学分析.结果:螺旋式扫描的辐射剂量明显低于步进式扫描,而2种扫描方式所得的图像质量差异无统计学意义,病灶检出和CT值测量也基本相同.结论:在保证CT图像满足诊断需要的前提下,应根据不同情况,选择合适的扫描方式,既提高病变检出的敏感性,又降低辐射剂量.     

改变体位联合 CT 靶扫描对特殊部位肺结节的诊断价值

目的：探讨改变体位联合C T靶扫描技术在特殊部位肺结节诊断中的价值。方法对22例行常规胸部C T扫描发现的位于心脏旁和后肋膈角的肺结节患者,增加改变体位及CT 靶扫描,记录2种扫描方法所得的图像的信噪比（SNR）和对比信噪比（CNR）,从肺野充气膨胀程度、伪影严重程度、肺血坠积效应3方面主观评价图像质量,对比分析2种扫描方法对病灶CT征象的显示情况,评价医师对肺结节的诊断信心度,并进行统计学分析。结果与常规胸部CT 扫描靶重建相比,改变体位靶扫描的图像质量主观评分提高（P＜0．01）,图像的SNR和CNR增加（P＜0．05）,对病灶CT征象显示情况得分提高（P＜0．05）,诊断信心度增加（P＜0．01）。结论改变体位联合CT靶扫描技术可以使结节征象显示更清楚,应作为心脏旁和后肋膈角肺结节的最佳扫描方法。     

Image quality of multisection CT of the brain: thickly collimated sequential scanning versus thinly collimated spiral scanning with image combining

BACKGROUND AND PURPOSE: Routine CT of the brain is traditionally performed with sequential CT. We assessed whether sequential CT can be replaced with thinly collimated multisection spiral CT without loss of image quality. MATERIALS AND METHODS: An observer study was conducted using data from 23 patients who were scanned with both a sequential (collimation, 4 x 5 mm) and a spiral technique (collimation, 4 x 1 mm; pitch, 0.875). Each sequential image was registered with 4 combined spiral CT images at 1.2 mm distance. Two neuroradiologists blindly scored 232 image pairs on 6 aspects: streak artifacts, visualization of brain tissue near skull, visualization of hypoattenuated lesions, gray/white matter differentiation, image noise, and overall image quality. A 5-point scale (range, -2 to 2) was used to score the preferences. The 23 pairs of complete scans were scored likewise. In this case, no registration was performed. RESULTS: Virtually all mean scores were positive (ie, showed a preference for the spiral technique). For the comparison of image pairs, the preferences with respect to streak artifacts (mean score, 1.36), visualization of brain tissue near the skull (mean score, 0.69), and overall image quality (mean score, 0.95) were significant (P < .001). With respect to visualization of hypo-attenuated lesions, image noise, and gray/white matter differentiation (mean scores, 0.18, 0.27, and 0.13), the preferences for spiral CT were not significant. The preferences for the spiral technique were also present at the comparison of the complete scans. CONCLUSION: Thinly collimated multisection spiral CT of the brain with image combining is superior to thickly collimated sequential CT.