S3图像重建软件临床应用的探讨

目的:探讨一种新的重建技术改善CT图像的空间和密度分辨率,从而提高CT的诊断率。材料与方法:使用ELSCINT公司CT-TWIN flash螺旋CI机。收集188例患者分别作胸部和鼻咽部CT扫描,用新重建技术-S3重建算法和常规重建算法分别重建图像,作对照分析。结果:S3重建算法重建的图像比常规重建能显示更多的肺部和骨髂的解剖结构及病灶细节。两种重建方式都能清晰显示软组织结构。结论:S3重建算法能明显提高图像的空间分辨率,又能保持良好的密度分辨率,完善了CT图像的质量,提高了CT诊断的准确性。     

多层螺旋CT脑血管成像技术探讨

CT血管成像 (CTA)已成为诊断脑部疾病的重要方法之一 ,而多层螺旋CT (MSCTA)具有扫描速度快、时间分辨率高、空间分辨率高、解剖覆盖面长、后处理技术多样等功能 ,使CTA图像质量更好。但图像质量的好坏还与扫描参数的设定 ,造影剂的用量及注射速度和图像后处理等技术密切相关 ,本文我们主要就多层螺旋CT扫描参数变化对CTA图像质量的影响进行了初步研究 ,现报道如下 :1　材料与方法1 1　一般资料　选择 4 0例脑部强化病例 ,年龄 18～ 5 5岁 ,平均 38岁 ,将其随机分成四组 ,如下表 :例数准直mm有效层厚mm扫描间隔mm螺距第一组 10 1 0 …     

低剂量双螺旋CT薄层扫描筛查早期肺癌初步研究

目的 探讨低剂量双排探测器螺旋CT薄层扫描筛查早期肺癌的最佳扫描参数及其应用价值。方法 通过在不同扫描参数下对水模进行常规剂量及低剂量螺旋CT薄层扫描，评定不同扫描条件下采集图像的空间分辨力、密度分辨力、噪声水平和辐射剂量，选择最佳扫描参数。对40名健康志愿者(体重小于75kg)的三个特定层面进行常规剂量及低剂量螺旋CT薄层扫描，评定对肺细微解剖结构、纵隔结构分辨能力和图像的伪影及噪声水平。对150名无症状体检者进行胸部健康体检，评价胸部病变检出能力。结果 采用低剂量螺旋CT薄层扫描水模，在30mAs，床速6．0mm／9.0mm／rot条件下采集的图像可以清晰的分辨宽度为1．0mm的线对，5．0mm直径的圆形孔洞，单位面积辐射剂量为1．5～1．6mGy。不同扫描条件对图像的空间分辨力、密度分辨力、图像噪声，对识别肺纹理级别、亚段支气管、次级肺小叶及纵隔结构是有显著影响的，0．7s／rot-6．0 HS-45mA与1．0s／rot-9．0HS-30mA条件下采集的图像可满足临床需要，后者略优于前者。对150名无症状体检者进行筛查，共检出结节或肿块46个，气管及亚段支气管管壁局限性增厚2例，腔内隆起3个。结论 选定1．0s／rot-9．0HS-30mA，AAR2为最佳扫描方案。低剂量螺旋CT薄层扫描具有辐射剂量小，敏感性及性价比高的特点，适用于肺癌高危人群的筛查。     

多层螺旋CT低剂量扫描在胸部应用的探讨

目的：探索多层螺旋CT在胸部低剂量扫描的可能性和合理性。方法：1）X线照射剂量测试：采用美国NE公司的NE2570／1的X线射剂量仪，用120kV、0．75s、分别测试8mm、5mm、3mm、1mm层厚的115mAs、75mAs、40mAs、25mAs、7.5mAs X线照射剂量，并加以比较。2）水模测试：在水模的同一层面，用120kV、0．75S分别作8mm、5mm、3mm层厚的115mAs 40mAs、25mAs扫描。在每幅图像的相同位置测6个兴趣区，作CT值的统计处理。3）病例CT扫描：随机选择肺部块影和片状影的病人各20例。用120kV、0．75s、8mm层厚在同一层面作115mAs、40mAs、25mAs、15mAs、7．5mAs扫描，另选5例作190mAs、150mAs、40mAs、25mAs、15mAs螺旋扫描。作不同厚度的重建间隔对比和后处理图像MIP、CVR、MPR、HRCT、3D、仿真支气管镜等效果比较。4）图像质量评估：由4名CT医生盲法评价CT图像。按照正常图像（O）；图像有少许伪影（＋）；图像有严重伪影(＋＋）的等级评判每一幅图像， 进行统计学处理。结果:1）照射剂量测试表明，115mAs的X线照剂量大于75mAs、40mAs、25mAs、7．5mAs分别为1．5倍、3倍、5倍、14倍。2）水模测试结果，8mm层厚的115mAs与40mAs；115mAs与25mAs；5mm层厚的115mAs与40mAs之间CT值P＞0．05； 其它为P＜0．05。3）图像质量评价结果，115mAs、40mAs、25mAs正常图像百分率的X^2检验，纵隔窗为0．025＞X^2＞0．01；肺窗为0．25＞X^2＞0．1。后处理图像25mAs以上剂量差异不显。结论：多层CT低剂量扫描技术可以有效保护病人和保证图象质量。     

双层螺旋CT扫描/重建参数对胸部图像质量的影响

影响双层螺旋CT图像质量的因素很多 ,包括螺距、有效层厚、重建间距等。本文旨在探讨不同扫描 /重建参数对胸部图像质量的影响。1　材料和方法对 10位志愿者作胸部CT扫描 ,应用不同扫描/重建参数 ,进行双层螺旋CT扫描。采用PHILIPS公司MX 80 0 0D双层螺旋CT扫描机。扫描条件包括 :螺距分别为 0 .875和 1.5 ;有效层厚分别为 10 .4mm和 6 .5mm ,有效层厚 10 .4mm条件下重建间距分别为 10 .4mm、5 .2mm ;有效层厚为 6 .5mm条件下重建间距分别为 6 .5mm、3.2mm。扫描KV固定为 12 0KV ,mA固定为 15 0mA ,时间固定为 0 .75s。应用上述扫…     

多层螺旋CT主要性能指标的探讨

目的：探讨GE Lightspeed Ultra多层螺旋CT的主要性能指标。方法：采用GE公司的多层螺旋CT－Lightspeed Ultra 及Catphan模、AAPM模测试比较其主要性能指标。结果：采用不同的模体测试时，多层螺旋CT的主要性能指标会略有偏差，但都基本接近其标称值。结论：多层螺纹CT-Lightspeed Ultra具有较好的综合性能，特别是具有更快的容积扫描速度及后处理能力，既可进行大范围的薄层扫描，又可进行回顾性薄层重建。     

多层面CT机的性能自动测试及评估

目的　探讨测量多层面螺旋CT机的方法和技术 ,评价其性能质量。方法　采用Catphan体模对PickerMX80 0 0进行自动测试 ,测量了设备的空间分辨率、低对比度分辨率、噪声、CT值等性能参数。结果　多层面CT机的质量与插值方法、螺距等因素有关。结论　多层面CT能够提供与单层面CT机一样的质量 ,而单位时间的扫描范围是单层面CT机的 2～ 3倍 ,多层面CT机是CT未来发展的一个主要方向。     

纵隔肿瘤的CT诊断与探讨

胸部CT扫描最重要的是检查纵隔，因为普通X线片只能显示突出于纵隔以外与肺成交界面的病变。纵隔内的病变因影像重迭很难用正侧位胸片显示，CT具有较高的密度分辨率，能够分辨4mm物体0．3％的密度差，而普通X线片的密度分辨率为2％，所以CT能分辨肿块是实性或近似水密度的囊肿、低密度的脂肪或高密度的钙化。一般不做增     

多层螺旋CT在冠状动脉成像中的技术条件与应用现状

无创性CT冠状动脉成像技术是目前CT技术发展的重要方向。双源CT、低剂量双能量CT与256层螺旋CT扫描速度达到或接近0．30s，检查时间达到0．04s。提高了CT的时间分辨率、空间分辨率，满足在一个心动周期时相内获得重建冠状动脉技术需要。应用中仍然存在影响冠状动脉成像质量的因素，如心率、重建图像质量、空间分辨率、冠状动脉狭窄与支架再狭窄评价与造影剂等。     

肺部CT图像重建技术的临床应用

CT应用在肺部扫描，具有良好的对比度及极高的分辨率，对肺部疾病的发现及诊断具有很高的价值，如果采用高分辨事CT扫描技术，加上正位（冠状面）、侧位（矢状面）、及测斜位重建技术的应用，更能发现及诊断肺部的细小病灶，多方位地、直观显示病灶的空间位置及肺门处气管、支气管的影像。l方法1．三机型：GEProsPeed。1．2扫描条件及方法：120by，300mA，IS。层厚10mm，由肺尖至隔顶快速扫描。扫描方法采用分段扫描的方式，即小病灶区薄扫3～smm，肺门部10Turn，上下肺野各用13～15mm层间距。这样，可适当地降低扫描层数，减少病人的…     

胸膜转移瘤的CT诊断价值

目的 探讨胸膜转移瘤的CT特征,提高胸膜转移瘤的认识与诊断水平.方法 回顾性分析近年在我院做CT检查的30例经病理及临床证实胸膜转移瘤病例,使用GE公司生产的Hispeed.zx/i型单层螺旋CT机,层厚、层距均为10 mm,螺距1.5,病分病例行5 mm薄层或高分辩扫描,所有病例均先行平扫,25例做了增强扫描.结果 胸膜转移瘤的CT表现依次为：包裹性胸腔积液伴不规则胸膜增厚（56.6%）、胸膜结节及结节状胸膜增厚（46.6%）、胸膜软组织肿块（13.3%）、少量气胸（1.0%）等,包裹性胸腔积液及胸膜结节或结节状胸膜增厚共占76.6%,增强扫描胸膜软组织灶呈中等度以上强化,CT值＞20 HU,66.6%病例并其他胸内转移征象,73.3%原发灶为肺癌,20.0%找不到原发灶.结论 螺旋CT能发现大部分胸膜转移瘤,结合原发灶病史及其他胸内转移征象,大部分病例能作出正确诊断,但对表现为少量胸腔积液或轻度带状胸膜增厚与反应性改变尚难鉴别,诊断有局限性.     

对MRI设备层间射频信号干扰进行检测的实践

目的 对3台MRI设备的层间射频信号干扰情况进行检测,以加深对层间射频信号干扰现象的认识。方法 通过3台MRI设备（设备1：GE 1.5T HDi,装机时间：2012年;设备2：GE 3.0T HD,装机时间：2006年;设备3：GE 3.0T 750W,装机时间：2016年）采用轴位T1WI序列扫描ACR模体,记录层间距为5.0、1.0、0.5和0 mm时的SNR,绘制SNR变化百分比与层间距百分比的函数图。处置标准：当层间距从5 mm减小到0时,由层间射频信号干扰作用所导致的SNR的下降不超过20%。结果 当层间距由5 mm减小到0时,设备1的SNR下降幅度为18.16%,设备2的SNR下降幅度为23.57%,设备3的SNR下降幅度为10.75%;设备1和设备3的层间射频信号干扰检测结果达到处置标准,设备2（使用时间超过10年）的检测结果未达标。结论 3台MRI设备都存在不同程度的层间射频信号干扰现象,其中使用时间最久的设备检测结果不达标。层间射频信号干扰检测应该在临床质量控制工作中受到重视。     

Oral contrast omission in the computed tomographic evaluation of blunt abdominal trauma: a literature review

The purpose of this review is to examine existing research on oral contrast administrating as it pertains to the computed tomographic (CT) evaluation of blunt abdominal trauma, as well as to determine the necessity of oral contrast as part of a CT scanning universal protocol. Many hospitals routinely administer both oral and intravenous contrast prior to abdominal CT scan. There have been found to be numerous disadvantages and risks associated with oral contrast administration prior to CT scan. There has been a shift in many hospitals over the years from traditional CT scanners to multidetector row helical scanners, which allow for thinner collimation and higher spatial resolution. With the advances in technology, from single detector row to multidetector row helical CT scanners, the question whether oral contrast is necessary, useful, or dangerous presents itself. There is a significant lack of research on this topic over the past 10 years. All of the studies referenced support no longer administering oral contrast for the initial evaluation of the patient with blunt abdominal trauma. However, the findings of the studies cited in this article are based on small sample sizes and low incidences of solid organ, bowel, or mesenteric injuries. The current level of available research has significant limitations to support a recommendation to eliminate the administration of oral contrast before obtaining the initial CT scanning for blunt abdominal trauma. Further research is necessary before any conclusion or practice change can be made.     

A comparison of the imaging performance of high resolution ultrasound scanners for preclinical imaging

Nine ultrasound transducers from six ultrasound scanners were assessed for their utility for preclinical ultrasound imaging. The transducers were: L8-16, L10-22 (Diasus; Dynamic Imaging Ltd., Livingston, UK); L17-5, L15-7io (iU22; Philips, Seattle, WA, USA), HFL38/13-6 (MicroMaxx; Sonosite Inc., Bothell, WA, USA); il3Lv (Vivid 5; GE, Fairfield, CT, USA), RMV 704 (Vevo 770; Visualsonics Inc., Toronto, Canada) and MS550S, MS550D (Vevo 2100; Visualsonics Inc.). A quantitative analysis of the ultrasound images from all nine transducers employed measurements of the resolution integral as an indication of the versatility and technology of the ultrasound scanners. Two other parameters derived from the resolution integral, the characteristic resolution and depth of field, were used to characterise imaging performance. Six of these transducers were also assessed qualitatively by ultrasonically scanning 59 female common marmosets (Callithrix jacchus) yielding a total of 215 scans. The quantitative measurements for each of the transducers were consistent with the results obtained in the qualitative in vivo assessment. Over a 0-10 mm imaging depth, the values of the resolution integral, characteristic resolution and depth of field, measured using the Edinburgh Pipe Phantom, ranged in magnitude from 7-72, 93-930 μm and 3.3-9.2 mm respectively. The largest resolution integrals were obtained using the Vevo 770 and Vevo 2100 scanners. The Edinburgh Pipe Phantom provides a quantitative method of characterising the imaging performance of preclinical imaging scanners. (E-mail: Carmel.Moran@ed.ac.uk)     

Quantitative Effects of Contrast Enhanced CT Attenuation Correction on PET SUV Measurements

Purpose The presence of contrast materials on computed tomography (CT) images can cause problems in the attenuation correction of positron emission tomography (PET) images. These are because of errors converting the CT attenuation of contrast to 511-keV attenuation and by the change in tissue enhancement over the duration of the PET emission scan. Newer CT-based attenuation correction (CTAC) algorithms have been developed to reduce these errors. Methods To evaluate the effectiveness of the modified CTAC technique, we performed a retrospective analysis on 20 patients, comparing PET images using unenhanced and contrast-enhanced CT scans for attenuation correction. A phantom study was performed to simulate the effects of contrast on radiotracer concentration measurements. Results There was a maximum difference in calculated radiotracer concentrations of 5.9% within the retrospective data and 7% within the phantom data. Conclusion Using a CTAC algorithm that de-emphasizes high-density areas, contrast-enhanced CT can be used for attenuation mapping without significant errors in quantitation.     

Contrast agent comparison for three‐dimensional micro‐CT angiography: A cadaveric study

Barium sulfate and lead oxide contrast media are frequently used for cadaver‐based angiography studies. These contrast media have not previously been compared to determine which is optimal for the visualisation and measurement of blood vessels. In this study, the lower limb vessels of 16 embalmed Wistar rats, and four sets of cannulae of known diameter, were injected with one of three different contrast agents (barium sulfate and resin, barium sulfate and gelatin, and lead oxide combined with milk powder). All were then scanned using micro‐computed tomography (CT) angiography and 3‐D reconstructions generated. The number of branching generations of the rat lower limb vessels were counted and compared between the contrast agents using ANOVA. The diameter of the contrast‐filled cannulae, were measured and used to calculate the accuracy of the measurements by comparing the bias and variance of the estimates. Intra‐ and inter‐observer reliability were calculated using intra‐class correlation coefficients. There was no significant difference (mean difference [MD] 0.05; MD 95% confidence interval [CI] ‐0.83 to 0.93) between the number of branching generations for barium sulfate‐resin and lead oxide‐milk powder. Barium sulfate‐resin demonstrated less bias and less variance of the estimates (MD 0.03; standard deviation [SD] 1.96 mm) compared to lead oxide‐milk powder (MD 0.11; SD 1.96 mm) for measurements of contrast‐filled cannulae scanned at high resolution. Barium sulfate‐resin proved to be more accurate than lead oxide‐milk powder for high resolution micro‐CT scans and is preferred due to its non‐toxicity. This technique could be applied to any embalmed specimen model. Copyright © 2016 John Wiley & Sons, Ltd.     

Peripancreatic arteries in thin-section multislice helical CT

BACKGROUND: The normal and pathologic anatomies of the peripancreatic arteries were demonstrated using thin-section multislice computed tomography (CT). METHODS: Triple-phase dynamic CT was performed in 304 consecutive patients without pancreatic pathology and in 22 patients with pancreatic carcinoma. CT angiographies images (2.5-mm collimation, multihelical pitch 3, HQ mode) and a 1.25-mm reconstruction interval were obtained with a GE Lightspeed Qx/i at 25, 40, and 80 s after bolus injection of 130-150 mL of iodinated contrast medium at a rate of 3-5 mL/s. The images were assessed mainly by the manual cine paging method. RESULTS: The anterior and posterior arcades and the dorsal pancreatic artery were frequently visualized. However, small-caliber arteries smaller than 1.5 mm in diameter, such as the pancreaticomagna, caudal pancreatic, and transverse pancreatic arteries, were infrequently visualized. In some cases, the peripancreatic arteries were very useful for differentiating the origin of tumors. CONCLUSION: Multislice helical CT enables the recognition of small peripancreatic arteries, and evaluation of these arteries should be considered when assessing tumors in the pancreaticoduodenal region.     

Sixteen-row multislice computed tomography: basic concepts, protocols, and enhanced clinical applications.

Since its introduction, spiral computed tomography (CT) technology underwent a continuous and fast technical and clinical development. In particular, spatial and temporal resolutions were constantly increased during the last decade. The main breakthrough for clinical application was the introduction of multislice technology, first with 2-row and 4-row equipment and more recently with 16-row scanners. A high-resolution sub-millimeter CT dataset can be acquired easily, although with an increased x-ray exposure for the patient. The high speed of the scan requires up-to-date and careful protocol optimization. Scanner technology and geometry affect image formation procedure and imaging protocols should be adapted accordingly. The technical foundations of spiral CT imaging and the main scan and reconstruction parameters are described in this article. Updated protocols and clinical examples of the latest applications are also discussed.     

冠状动脉CT血管成像扫描与报告书写专家共识

冠状动脉CT血管成像(coronary computed tomography angiography, CCTA)检查已成为临床筛查冠状动脉疾病安全、可靠的首选技术之一。随着技术发展, 后64排高端CT设备近年已有大量装机, 但在扫描适应证、扫描方式及对比剂使用等方面仍存在大量不合理、不规范的现象, CCTA扫描与报告书写的规范化、标准化应用水平亟待提高。制定本共识的目的即是建立可共同遵循的扫描适应证及规范化扫描方案和影像报告等指导原则, 以便在全国范围内进行规范化推广应用。     

Coronary calcium mass scores measured by identical 64-slice MDCT scanners are comparable: a cardiac phantom study

To assess whether absolute mass scores are comparable or differ between identical 64-slice MDCT scanners of the same manufacturer and to compare absolute mass scores to the physical mass and between scan modes using a calcified phantom. A non-moving anthropomorphic phantom with nine calcifications of three sizes and three densities was scanned 30 times on three 64-slice MDCT scanners of manufacturer A and on three 64-slice MDCT scanners of manufacturer B in both sequential and spiral scan mode. The mean mass scores and mass score variabilities of seven calcifications were determined for all scanners; two non-detectable calcifications were omitted. It was analyzed whether identical scanners yielded similar or significantly different mass scores. Furthermore mass scores were compared to the physical mass and mass scores were compared between scan modes. The mass score calibration factor was determined for all scanners. Mass scores obtained on identical scanners were similar for almost all calcifications. Overall, mass score differences between the scanners were small ranging from 1.5 to 3.4% for the total mass scores, and most differences between scanners were observed for high density calcifications. Mass scores were significantly different from the physical mass for almost all calcifications and all scanners. In sequential mode the total physical mass (167.8 mg) was significantly overestimated (+2.3%) for 4 out of 6 scanners. In spiral mode a significant overestimation (+2.5%) was found for system B and a significant underestimation (−1.8%) for two scanners of system A. Mass scores were dependent on the scan mode, for manufacturer A scores were higher in sequential mode and for manufacturer B in spiral mode. For system A using spiral scan mode no differences were found between identical scanners, whereas a few differences were found using sequential mode. For system B the scan mode did not affect the number of different mass scores between identical scanners. Mass scores obtained in the same scan mode are comparable between identical 64-slice CT scanners and identical 64-slice CT scanners on different sites can be used in follow-up studies. Furthermore, for all systems significant differences were found between mass scores and the physical calcium mass; however, the differences were relatively small and consistent.