CT三维重建对颅底病变的应用价值

目的：探讨ＣＴ三维重建（３ＤＣＴ）对颅底病变的临床应用价值。材料和方法：对２０例颅底不同病变行螺旋ＣＴ扫描三维重建，采用表面阴影显示法重建，把重建图像旋转不同的角度。测量病变的大小和体积。初步设计开颅骨窗的位置、大小，追踪其手术过程和结果。结果：３ＤＣＴ能直观地显示病变大小、形态、位置，精确测量病变的大小、体积。确定手术入路和骨窗的位置、大小。结论：３ＤＣＴ是２ＤＣＴ的有用补充，特别是对外科术前治     

螺旋CT三维重建的方法及技巧

目的 探讨螺旋ＣＴ三维重建的实用方法和技巧。方法 选择成功地进行了三维重建的２００例骨和血管病变。扫描层厚３￣５ｍｍ,重建间隔２￣３ｍｍ,螺距０．５￣１,数据输入工作站,用遮盖表现显示法进行处理。结果 全部病例的三维立体显示良好,病变整体形态、与周围结构的关系从不同位置和角度得以观察。结论 高质量的三维图像依赖于技术参数的合理选择匹配,以及医技人员的操作技巧和熟练程度以及扫描机器的质量。     

螺旋CT三维成像在颞部及颜面部的应用

目的评价螺旋ＣＴ三维成像技术对颞部及颜面部病变的诊断作用。方法对１９例颞部病变和１７例颜面部病变进行了高速螺旋扫描和三维重建，并从多方向观察三维重建图像。使用的螺旋ＣＴ装置为东芝ＸＦｏｒｃｅ、螺旋ＣＴ三维成像装置为ＸＬｉｎｋ５０。结果螺旋ＣＴ三维成像技术能清楚地立体显示病变的部位和范围。结论螺旋ＣＴ三维成像技术能对颞部及颜面病变的术前诊断提供有价值的信息和发挥重要作用     

螺旋CT三维重建肺结节性病变初步探讨

螺旋ＣＴ三维重建肺结节性病变初步探讨宋金松１严洪珍２姚绍鑫２螺旋ＣＴ扫描是近年发展起来的一种新的ＣＴ扫描技术，其扫描轨迹为螺旋形曲线，一次收集扫描范围内全部容积数据，又称容积ＣＴ扫描〔１〕。本文旨在探讨螺旋扫描三维重建肺结节性病变的条件，评价其临床价...     

人颞下颌关节CT三维重建及其有限元实体建模

目的：由活体直接获得人颞下颌关节（包括下颌骨、关节盘及关节结节）的三维影像,以建立其三维有限元模型。材料与方法：利用ＡｕｔｏＣＡＤ软件及螺旋ＣＴ扫描技术与三维有限元分析方法相结合,将ＣＴ扫描图像转换为可用于有限元实体建模的数字图像。结果：三维有限元实体模型与螺旋ＣＴ三维重建影像比较,几何相似性与还原性良好,材料构造合理,并由此建立了理想的人颞下颌关节三维有限元模型。结论：在临床实践中,借助于螺旋ＣＴ扫描及Ａｕｔｏ－ＣＡＤ软件在活体建立人颞下颌关节三维有限元模型是切实可行的,结果是满意的。     

多层螺旋CT三维重建技术在颅骨修补术中的应用

目的探讨螺旋CT三维容积重建技术在颅骨缺损患者中的使用技巧和计算机个性化设计钛网在临床的应用。方法30例颅骨缺损患者行螺旋CT扫描,数据传至工作站行三维重建,应用计算机辅助设计（CAD）和制造技术（CAM）进行个性化的颅骨缺损修复体的预制,并应用于临床。结果根据CT数据制作的三维模型能精确地显示颅骨缺损区域的结构,修复体嵌合满意,术后无并发症。结论多层螺旋CT三维重建技术在颅骨缺损修复术中具有重要的临床实用价值。     

容积重建(VR)法的技术参数及应用

目的：探讨螺旋ＣＴ三维容积重建（ｖｏｌｕｍｅ ｒｅｎｄｅｒｉｎｇ,简称ＶＲ）的实用方法和技巧,扩大其临床应用范围,方法：ＶＲ三维重建１００例包括：①血管组４９例,②骨关节组３０例,③其它部位组２１例。扫描层厚为１ｍｍ、２ｍｍ、３ｍｍ、５ｍｍ,重建间隙０．９ｍｍ、１．４ｍｍ、２．３ｍｍ,螺距１～２,重建方式为容积重建。结果：全部病例三维立体显示良好。图像柔和自然,病变整体形态及周围结构的关系明确,并     

螺旋CT扫描成像质量分析

目的：通过对螺旋与常规ＣＴ扫描的比较，图像的分析和讨论，以期为临床诊断提供有用的依据。材料和方法：螺旋及常规ＣＴ扫描采用Ｓｏｍａｔｏｍ Ｐｌｕｓ全身ＣＴ扫描机。扫描体模：（１）玻璃球，直径１．５ｃｍ，误差〈１０μｍ；（２）有机圆柱体，直径３．０ｃｍ，误差〈８μｍ；（３）水模，直径２５ｃｍ。扫描条件相同情况下，在下述方面进行比较：（１）不同物体螺旋ＣＴ扫描图像还原性的影响；（２）不同螺距扫描与图像分     

颌面部骨折三维重建技术

将螺旋ＣＴ连续横断扫描所获得的容积数据信息在Ｓｕｎ工作站上进行图像后处理 ,重建出直观的 3ＤＣＴ图像。立体图像不仅有助于放射科医生的诊断 ,同时也给临床医生提供了更丰富、精确的信息 ,从而为科学制定治疗计划提供帮助。1　材料与方法1.1　本组 12例 ,男 9例 ,女 3例 ,年龄 16～ 40岁 ,平均 3 2 .6岁。单发骨折 3例 ,多发骨折 9例 ;车祸伤 8例 ,坠落伤 4例。伤后 3ｈ～ 4ｄ内行ＣＴ扫描和三维重建成像。1.2　机器设备和成像方法　采用日本东芝ＸｖｉｓｏｎＧＸ螺旋ＣＴ行颌面部非增强螺旋扫描 ,螺距 1,层厚 2 .5ｍｍ。扫描条件为3 0…     

颅内病变三维CT成像技术的临床应用

目的：探讨三维ＣＴ成像在颅内病变中的临床应用价值。材料与方法：对７１例颅内病变患者行螺旋ＣＴ增强扫描,然后对颅内血管和／或病变进行三维重建。其中２３例进行ＣＴ血管造影（ＣＴＡ）扫描,４８例非ＣＴＡ扫描。结果：（１）２３例ＣＴＡ扫描者,血管表面遮盖法（ＳＳＤ）与最大强度投影法（ＭＩＰ）重建都能显示颅内动脉的第３组分支。ＳＳＤ对显示血管的立体空间关系比较直观;ＭＩＰ图像类似ＤＳＡ图像。（２）３３例颅内     

双螺旋CT门脉血管成像理想扫描参数和方法的研究

目的；探讨双螺旋CT门脉血管成像（DSCTP）理想扫描层厚，螺距，三维成像技术，资料与方法：采用Elscint双螺旋CT机扫描，94例患者，分为3组：A组：螺距1，层厚2.5mm，B组；螺距1．5，层厚2．5;3C,螺距1，层厚5mm，以最大强度投影法（MIP），表面阴影显示地（SSD）重建门静脉三维影像。比较不同层厚和螺距组合，不同成像技术对门脉显示的差别。比较各组横断面图像噪声大小及对DSCTP的影响。结果：（1）DSCTP图像质量，A、B组的效果均佳，优于C组。（2）MIP较SSD显示的血管丰富，小分支显示优于SSD。（3）B组噪声最大，但对DSCTP无明显影响。结论：DSCTP最佳扫描层厚为2.5mm，螺距为1.5,MIP为理想三维成像技术。     

胸部螺旋CT技术参数的最佳选择及应用

本文目的在于通过对螺旋ＣＴ及常规ＣＴ影像进行对比。取得肺成像的最佳螺旋ＣＴ扫描条件。作者对钨丝模型、低对比模型、空气干燥膨胀肺标本在相同ｋＶ、ｍＡｓ条件下进行不同层厚、不同重建算法、不同螺距的螺旋ＣＴ扫描及常规ＣＴ扫描，分析两种扫描成像的分辨率差异，支气管及血管的可见度及噪音。结果显示薄层、超高分辨、高分辨重建算法时影像分辨率高。厚层、标准、软组织重建算法时两种扫描方式影像略有差异。作者还对３２例     

The Quality of Reconstructed 3D Images in Multidetector-Row Helical CT: Experimental Study Involving Scan Parameters

Objective

To determine which multidetector-row helical CT scanning technique provides the best-quality reconstructed 3D images, and to assess differences in image quality according to the levels of the scanning parameters used.

Materials and Methods

Four objects with different surfaces and contours were scanned using multidetector-row helical CT at three detector-row collimations (1.25, 2.50, 5.00 mm), two pitches (3.0, 6.0), and three different degrees of overlap between the reconstructed slices (0%, 25%, 50%). Reconstructed 3D images of the resulting 72 sets of data were produced using volumetric rendering. The 72 images were graded on a scale from 1 (worst) to 5 (best) for each of four rating criteria, giving a mean score for each criterion and an overall mean score. Statistical analysis was used to assess differences in image quality according to scanning parameter levels.

Results

The mean score for each rating criterion, and the overall mean score, varied significantly according to the scanning parameter levels used. With regard to detector-row collimation and pitch, all levels of scanning parameters gave rise to significant differences, while in the degree of overlap of reconstructed slices, there were significant differences between overlap of 0% and of 50% in all levels of scanning parameters, and between overlap of 25% and of 50% in overall accuracy and overall mean score. Among the 18 scanning sequences, the highest score (4.94) was achieved with 1.25 mm detector-row collimation, 3.0 pitch, and 50% overlap between reconstructed slices.

Conclusion

Comparison of the quality of reconstructed 3D images obtained using multidetector-row helical CT and various scanning techniques indicated that the 1.25 mm, 3.0, 50% scanning sequence was best. Quality improved as detector-row collimation decreased; as pitch was reduced from 6.0 to 3.0; and as overlap between reconstructed slices increased.     

多层螺旋CT仿真胃镜成像参数的实验模型研究

目的：系统分析多层螺旋CT（MSCT）主要扫描参数对CT仿真胃镜（CTVG）图像质量的影响，寻找可获得较好图像质量的扫描参数组合。方法：应用不同扫描参数分别对正常猪胃模型进行扫描。通过观察、评价CTVG图像质量，系统分析主要扫描参数对CTVG图像质量的影响，寻找可获得良好图像质量的扫描参数组合。结果：气量、准直宽度、重叠热重建率及重建算法的变化均会不同程度地影响CTVG图像质量。结论：选择适当的成像参数进行扫描和重建可获得微小结构分辨良好的优良三维图像，从而使CTVG技术成为显示胃部结构和病变的有效方法之一。     

Three-dimensional volumetric display of CT data: effect of scan parameters upon image quality

Of the many steps involved in producing high quality three-dimensional (3D) images of CT data, the data acquisition step is of greatest consequence. The principle of "garbage in, garbage out" applies to 3D imaging--bad scanning technique produces equally bad 3D images. We present a formal study of the effect of two basic scanning parameters, slice thickness and slice spacing, on image quality. Three standard test objects were studied using variable CT scanning parameters. The objects chosen were a bone phantom, a cadaver femur with a simulated 5 mm fracture gap, and a cadaver femur with a simulated 1 mm fracture gap. Each object was scanned at three collimations: 8, 4, and 2 mm. For each collimation, four sets of scans were performed using four slice intervals: 8, 4, 3, and 2 mm. The bone phantom was scanned in two positions: oriented perpendicular to the scanning plane and oriented 45 degrees from the scanning plane. Three-dimensional images of the resulting 48 sets of data were produced using volumetric rendering. Blind review of the resultant 48 data sets was performed by three reviewers rating five factors for each image. The images resulting from scans with thin collimation and small table increments proved to rate the highest in all areas. The data obtained using 2 mm slice intervals proved to rate the highest in perceived image quality. Three millimeter slice spacing with 4 mm collimation, which clinically provides a good compromise between image quality and acquisition time and dose, also produced good perceived image quality. The studies with 8 mm slice intervals provided the least detail and introduced the worst inaccuracies and artifacts and were not suitable for clinical use. Statistical analysis demonstrated that slice interval (i.e., table incrementation) was of primary importance and slice collimation was of secondary, although significant, importance in determining perceived 3D image quality.     

Optimization of scanning parameters for multi-slice CT colonography: experiments with synthetic and animal phantoms

AIM: To determine the optimal collimation, pitch, tube current and reconstruction interval for multi-slice computed tomography (CT) colonography with regard to attaining satisfactory image quality while minimizing patient radiation dose. MATERIALS AND METHODS: Multi-slice CT was performed on plastic, excised pig colon and whole pig phantoms to determine optimal settings. Performance was judged by detection of simulated polyps and statistical measures of the image parameters. Fat and muscle conspicuity was measured from images of dual tube-current prone/supine patient data to derive a measure of tube current effects on tissue contrast. RESULTS: A collimation of 4 x 2.5 mm was sufficient for detection of polyps 4 mm and larger, provided that a reconstruction interval of 1.25 mm was used. A pitch of 1.5 allowed faster scanning and reduced radiation dose without resulting in a loss of important information, i.e. detection of small polyps, when compared with a pitch of 0.75. Tube current and proportional radiation dose could be lowered substantially without deleterious effects on the detection of the air-mucosal interface, however, increased image noise substantially reduced conspicuity of different tissues. CONCLUSION: An optimal image acquisition set-up of 4 x 2.5 mm collimation, reconstruction interval of 1.25 mm, pitch of 1.5 and dual prone/supine scan of 40/100 mA tube current is proposed for our institution for scanning symptomatic patients. Indications are that where CT colonography is used for colonic polyp screening in non-symptomatic patients, a 40 mA tube current could prove satisfactory for both scans.     

Optimization of the technique of virtual colonoscopy using a multislice spiral computerized tomography

PURPOSE: To optimize scanning parameters for virtual colonoscopy utilizing a multislice Helical CT scanner in an in vitro study (using a homemade colonic phantom) and in a preliminary clinical study. MATERIAL AND METHODS: A colonic phantom was built using a plastic tube and 12 plastiline polyps were placed inside. The colonic phantom was studied with a multislice Helical CT scanner. Axial images were obtained with the phantom parallel to the long axis of the moving table (in order to simulate the evaluation of ascending and descending colon): oblique images were acquired with the phantom at 45 degrees relative to the long axis of the moving table (in order to simulate the evaluation of sigmoid colon and colonic flexures). Four different scanning protocols were tested: 1) slice collimation, 5 mm; slice width, 7 mm; table speed, 25 mm; reconstruction index, 5 mm; 2) slice collimation, 2.5 mm; slice width, 3 mm; table speed, 15 mm; reconstruction index, 3 mm; 3) slice collimation, 1 mm; slice width, 1.25 mm; table speed, 5 mm; reconstruction index, 1 mm; 4) slice collimation, 1 mm; slice width, 1.25 mm; table speed, 4 mm; reconstruction index, 1 mm. Quantitative analysis consisted in evaluation of the number of identified polyps and polyp size along the longitudinal axis. Qualitative analysis consisted in the evaluation of image artifacts and quality of 3D reconstructed images (step artifacts and polyp geometry distortion). This preliminary clinical study was performed in 12 patients (7 men and 5 women) who underwent multislice Helical CT colonography. We selected patients with clinical indications for conventional colonoscopy or after unsuccessful conventional colonoscopy. RESULTS: Multislice Helical CT colonography was 100% sensitive in the detection of all polyps and in all scanning protocols. With oblique scans, only a 3-mm polyp was missed during protocol 1 (sensitivity: 92%). Polyp geometry distortion was observed on longitudinal reconstructions, whereas no distortion was seen on axial images. Image quality was graded as optimal for protocols 2, 3, and 4; protocol 1 was graded as good on transverse scans and as poor on oblique scans. In our preliminary clinical study, two colonic carcinomas and three polyps were identified. CONCLUSIONS: At present, the introduction of multislice technology in virtual colonoscopy permits to improve spatial resolution and image definition. The actual clinical advantage, in terms of increased diagnostic accuracy, needs further investigation in larger clinical studies.     

上气道螺旋CT三维重建技术及其临床应用价值

目的 探讨上气道的螺旋CT三维（3D）重建技术及其临床应用价值。材料与方法 对10例正常和36例上气道病变的患者进行轴位螺旋CT扫描,层厚3．0mm,正常组采用不同重建间隔、阈值作气道表面遮盖法（SSD）重建,病变组分别作气道SSD、Ray-Sum(表面透视法）重建和叠加成像。结果 采用1．0mm重建间隔、上层阈值为－500HU能获得最佳的气道SSD图像;SSD图像能清楚显示上气道的正常形态,多方位观察可全景地反映气道表面受压的情况,RaySum能更好地显示狭窄内缘的情况,9例（25％）病变组气道SSD显示正常;SSD图像上显示的肿瘤侵犯范围明显小于轴位和多平面重建（MPR）图像。叠加成像能清楚显示肿瘤与邻近结构尤其是血管、气道的关系。结论 3D重建能立体地显示上气道病变,是轴位和MPR图像的很好补充手段。     

Virtual computed tomography colonoscopy: artifacts, image quality and radiation dose load in a cadaver study

The purpose of our study was to evaluate the interdependency of spatial resolution, image reconstruction artifacts, and radiation doses in virtual CT colonoscopy by comparing various CT scanning protocols. A pig's colon with several artificial polypoid lesions was imaged after air insufflation with helical CT scanning using 1-, 3-, and 5-mm collimation, and pitch values varying from 1.0 to 3.0. Virtual endoscopic images and “fly through” sequences were calculated on a Sun Sparc 20 workstation (Navigator Software, GE Medical Systems, Milwaukee, Wis.). Several reconstruction artifacts as well as overall image quality were evaluated by three independent reviewers. In addition, radiation doses for the different CT protocols were measured as multiple-scan average dose using a 10-cm ion chamber and a standard Plexiglass body phantom. Generally, image quality and reconstruction artifacts were less affected by pitch values than by beam collimation. Thus, narrow beam collimation at higher pitch values (e. g. 3 mm/2.0) seems to be a reasonable compromise between quality of virtual endoscopic images and radiation dose load. Received: 4 February 1999; Revised: 16 June 1999; Accepted: 17 June 1999     

Effects of scanning and reconstruction parameters on image quality in electron-beam CT angiography: coronary artery phantom study

RATIONALE AND OBJECTIVES: This study compared the image quality obtained with different scanning and reconstruction parameters for electron-beam computed tomographic (CT) angiography and sought optimal methods for visualizing the coronary artery lumen. MATERIALS AND METHODS: Electron-beam CT angiography with contrast material enhancement was used to image 35 branches of fresh postmortem swine coronary arteries. Different collimation widths, fields of view (FOVs), reconstruction kernels, and algorithms were employed to reconstruct the acquired raw data into CT angiographic images. Image quality was compared and analyzed. RESULTS: The contrast-to-noise ratios (C/Ns) for 1.5-, 2-, and 3-mm section thickness were 28.4 +/- 15.2, 31.9 +/- 9.3, and 33.8 +/- 14.5, respectively (P < .05). The lengths of visualized coronary artery lumina were significantly longer for 1.5-mm scanning (71.6 mm +/- 4.3) than for 2-mm (58.3 mm +/- 5.5) and 3-mm scanning (59.0 mm +/- 8.0) (P < .01). The C/Ns for 12.7-, 18.0-, and 26.0-cm FOV reconstruction were 32.8 +/- 9.9, 28.9 +/- 8.2, and 27.1 +/- 8.2, respectively (not significant), and the visualized luminal lengths were 76.1 mm +/- 12.5, 71.7 mm +/- 14.6, and 65.4 mm +/- 13.1, respectively (not significant). The highest C/N (48.2 +/- 13.3) was achieved with smooth kernels and a cone-beam algorithm, and the lowest (14.7 +/- 3.4) with very sharp kernels and a normal algorithm. Cone-beam algorithm images had significantly higher C/Ns than did normal algorithm images (P < .001), and they demonstrated longer coronary artery lumina (P < .01). CONCLUSION: Collimation width, FOV, reconstruction kernels, and algorithms are important in the processing of high-quality electron-beam coronary angiograms. A 1.5-mm collimation width, 12.7-cm FOV, cone-beam reconstruction algorithm, and very sharp kernels should help in obtaining the best image quality and depicting the longest segments of coronary artery lumen.