双源CT低管电压及低剂量等渗对比剂在头颈部CTA中的初步研究

目的评估双源CT低管电压及低剂量等渗对比剂对头颈部CT血管造影图像质量和辐射剂量的影响。方法选取头颈部CTA患者60例,随机分成两组(各30例)。A组:管电压80/Sn140 k Vp,对比剂32ml(270mg I/ml)。B组:管电压100/Sn140 k Vp,对比剂40ml(370mg I/ml)。记录各段动脉CT值、噪声值、对比噪声比、信噪比,以及辐射剂量、碘摄入量、图像质量主观评分等,进行统计分析。结果除了A组的升主动脉噪声值明显高于B组(P0.01),两组图像的血管CT值、噪声值、信噪比、对比噪声比无统计学差异(P值均0.05)。A组辐射剂量明显低于B组,减少了23.8%(P0.001)。A组每例患者的碘摄入量较B组下降了41.6%。两组图像质量评分无统计学差异(P=0.844)。两名医生对图像质量一致性检验的Kappa值为0.663(P0.001)。结论双源CT低管电压及低剂量等渗对比剂可以用于头颈部CT血管造影,在满足诊断要求的基础上,能同时减少辐射剂量及碘摄入量。     

双源CT在急性胸痛诊断和鉴别诊断中的临床价值

目的：探讨双源CT在急性胸痛诊断和鉴别诊断中的临床价值。方法：51例急性胸痛患者行双源CT心脏及胸部血管检查,对图像进行重组并进行诊断,其中36例患者双源CT结果并与血管造影结果进行对比较。结果：所有患者一次心脏和胸部血管双源CT检查即可快速获得清晰的冠状动脉、肺动脉、胸主动脉及胸部其他结构。双源CT诊断冠状动脉狭窄或闭塞26例,其中5例并发急性心肌梗死,1例合并有冠状动脉夹层;肺动脉栓塞7例,胸主动脉夹层、壁间血肿和动脉瘤分别为6例、2例和2例。冠状动脉及胸主动脉双源CT结果与血管造影结果具有良好的一致性。结论：双源CT可以同时清晰地显示心脏及胸部血管,是急性胸痛病因诊断和鉴别诊断的无创、快速、可靠的检查方法。     

64排螺旋CT肺动脉与主动脉联合扫描技术

目的：探讨一次性完成肺动脉与主动脉 CT 造影检查技术。方法回顾性分析23例肺动脉与主动脉联合造影的患者CT 影像资料(A 组),另选肺动脉、主动脉 CT 造影正常的患者各13例为对照(B 组、C 组)。统计3组患者对比剂应用剂量和辐射剂量,观察异常血管显示情况,对比各组间正常肺动脉、主动脉 CT 值,以及4、5级肺动脉显示数量。结果A 组对比剂用量大于 B组和 C 组,但小于 B 组与 C 组之和;A 组辐射剂量与 C 组相当,明显少于 B 组与 C 组之和。23例中准确诊断6例肺动脉栓塞,1例肺动脉发育畸形;4例主动脉夹层,真假腔对比明显,5例主动脉炎,10例主动脉粥样硬化;结果正常者4、5级肺动脉显示数量、肺动脉与主动脉 CT 值和对照组对比均无统计学意义(P >0.05)。结论64排螺旋 CT 可一次性完成肺动脉与主动脉造影检查,对比剂用量和辐射剂量明显减少。     

个体化低剂量组合扫描方案对头颈部CTA图像质量及辐射剂量的影响

目的探讨个体化低剂量(低电流、大螺距、个体化低对比剂)组合扫描方案在头颅部CT血管成像技术(CTA)中对图像质量及辐射剂量的影响。方法选取我院自2014年7月～2015年7月间收治的行头颅部CTA检查的患者120例进行实验,根据检查方式的不同分成两组,对照组患者60例采用常规管电流、常规对比剂水平检查,观察组60例采用低对比剂、低管电流检查,对比两组患者所获得的图像质量、辐射剂量差异。结果两组患者在CT图像质量主客观评分差异无统计学意义(P 0. 05);两组患者对比噪声比(CNR)、信噪比(SNR)差异无统计学意义(P 0. 05),辐射剂量(ED)差异有统计学意义(P 0. 05)。结论个体化低剂量(低电流、大螺距、个体化低对比剂)组合扫描方案在头颅部CTA检查中应用获得图像质量与常规管电流、对比剂水平差异不明显,而患者吸收辐射剂量明显减少,扫描方案更加合理化、个性化。     

双源CT对急性胸痛的诊断价值

目的 评价双源CT胸痛三联扫描计划对急诊胸痛诊断的准确性.方法 按照入选标准连续选取急性胸痛患者56例,采用西门子双源CT扫描仪胸痛三联扫描计划进行胸部CTA扫描,采集时间83 ms,按照体质指数调整对比剂注射的流速及流量.扫描范围自第1肋骨到心脏膈面的整个胸部,自气管隆突水平启动心电门控.对比剂采用三相注射法以便同时显示主动脉、冠状动脉、肺动脉三大血管床.评价三大血管床的图像质量,测量血管增强CT值.对15例同时有冠状动脉造影者进行对照分析,其他患者均随诊30 d以上.结果除1例患者因屏气不好影响图像评价被排除本研究外,余55例患者的三大血管床(主动脉、冠状动脉、肺动脉)均得到明显均匀强化和良好图像质量.冠状动脉图像质量评分平均3.8分.对比剂平均用量为(88±5)ml.平均辐射剂量为11.6 mSv (95% CI 6.9～13.1).本组病例中13例CTA为阴性,其余42例中14例冠状动脉粥样硬化,其中13例冠状动脉狭窄程度＞50%,12例行冠状动脉造影支架植入术.11例患者为Stanford A型主动脉夹层,肺栓塞11例.总的胸痛病因分布较为复杂.7例患者合并2种以上胸部疾病.CTA在本组病例"急性胸痛三联征"诊断中总的敏感性为98%,特异性96%.CTA阴性的随访人群2例随后诊断为反流性食管炎,其余患者30 d内均无严重不良事件发生.结论双源CT的胸痛三联扫描计划为急性胸痛患者的快速诊断及急诊分类提供了安全、有效的手段.     

螺旋CT血管造影术在夹层动脉瘤诊断中的应用

目的评价螺旋CT血管造影技术在夹层动脉瘤诊断中的临床应用价值。方法21例夹层动脉瘤行螺旋CT连续容积增强扫描，并将获得的数据传至工作站行三维重建，结合横断面及三维重建图像进行分析。结果根据Debakey分型，De．bakeyⅠ型10例，DebakeyⅢ型11例，两型中不典型夹层各2例。典型夹层动脉瘤的CT征象主要是分离移位的内膜、真假腔、主动脉壁增厚、钙化、主动脉不规则扩张；不典型主动脉夹层动脉瘤的征象为主动脉壁呈半月状或环状增厚，伴或不伴有内膜钙化内移。结论螺旋CT血管造影检查在诊断主动脉夹层动脉瘤中是一种安全有效的便于治疗后观察对比的方法。     

低浓度对比剂大螺距前门控双源CT冠状动脉成像初步研究

目的:评价低浓度对比剂Flash双源CT大螺距冠状动脉成像联合应用低kV和迭代重建算法对血管强化程度、图像质量和辐射剂量的影响.方法:对120例体重指数(BMI)＜25 kg/m2、心率≤65次/分且稳定的患者进行前瞻性心电触发大螺距双源CT冠状动脉扫描,检查者随机分成低浓度对比剂组(A组,60例)和高浓度对比剂组(B组,60例).A组对比剂使用碘克沙醇(浓度为270mg I/mL),管电压为80 kV,图像重建采用迭代重建算法(SAFIRE);B组对比剂使用碘普罗胺(浓度为370mg I/mL),管电压为100 kV,图像重建采用滤波反投影算法(FBP).两组图像均测量左右冠状动脉开口处、升主动脉根部及心底层面的胸主动脉CT值,并比较两组图像的噪声、信噪比(SNR)、对比噪声比(CNR)、主观图像质量评分和有效辐射剂量.结果:碘克沙醇270组各解剖部位平均强化CT值均明显高于碘普罗胺370组,差异均具有统计学意义(P＜0.05).碘克沙醇270组图像噪声、SNR、CNR较碘普罗胺370组略高,但差异均无统计学意义(P＞0.05).两组主观图像质量评分分别为(1.62±0.69)和(1.51±0.65),差异克统计学意义(P＞0.05).碘克沙醇270组有效辐射剂量较碘普罗胺370组明显降低[分别为(0.25±0.05) mSv和(0.55±0.11) mSv,P＜0.001],低浓度组辐射剂量较高浓度组降低了54.5％.结论:当联合应用低kV和迭代重建算法时,即使使用低浓度对比剂(270 mg I/mL)进行Flash双源CT大螺距冠状动脉成像,依然可以提高血管的对比强化效果且不降低图像质量,还能大幅度降低有效辐射剂量.     

螺距的选择对胸腹主动脉夹层320层CT成像质量的影响

目的：探讨螺距的选择对320层CT螺旋扫描模式胸腹主动脉夹层图像质量及辐射剂量的影响。方法：连续纳入可疑急性主动脉综合征患者100例,分为两组,A组（50例）采用螺距为53、B组（50例）采用螺距为95进行胸腹主动脉CTA扫描。使用Toshiba Aquilion one 320 CT机,120 kV,450 mA,0.35 s/r。选用体部前置滤线器和后置过滤器,重建层厚0.5 mm。应用SPSS 11.5软件分别对A组和B组的CT有效辐射剂量、图像噪声均值进行非配对t检验。结果：A组平均有效辐射剂量为18.19 mSv,B组为9.52 mSv,较A组有效辐射剂量平均减少50%。A组患者平均扫描时间为9.5 s,B组为4.53 s,较A组扫描时间平均减少5.07 s。A组患者的对比剂总量平均为83.6 ml,B组为71.8 ml,较A组对比剂总量平均减少12 ml。结论：在进行胸腹主动脉CTA检查中管电压和管电流恒定不变的情况下选择大螺距扫描,可以减少扫描时间、对比剂量并显著降低辐射剂量,在保证图像质量的同时,主动脉根部搏动伪影减小,可显示冠状动脉开口及近段,从而达到优化图像的同时降低辐射剂量的目的。     

平板旋转血管造影及三维重组在主动脉病变中的应用

目的:评价平板旋转血管造影及三维重组在主动脉病变临床应用的价值.方法:对比分析31例主动脉病变患者的CT或MR、二维血管造影、旋转血管造影及三维重组影像学资料,并对其结果对比分析.31例均为男性,年龄18～81岁,平均56.5岁.结果:行胸主动脉造影28例,发现主动脉夹层25例,动脉瘤1例,假性动脉瘤1例,主动脉弓畸形1例.行腹主动脉造影3例,发现动脉瘤2例,1例为腹主动脉动脉硬化性改变并主动脉钙化.所有主动脉夹层、真性及假性动脉瘤造影与CT或MRI对比,病变的形态、大小、位置均相符.其中有2例夹层的造影提示CT诊断破口位置错误.1例主动脉弓畸形,CT误诊为动脉瘤,而造影则可以清晰显示扩张纡曲的畸形主动脉弓.其中23例主动脉夹层和3例真性动脉瘤造影后进行支架主动脉腔内隔绝术的介入治疗,术后均行二维血管造影,支架位置准确,隔绝效果良好,没有出现并发症.结论:平板旋转血管造影及三维重组对主动脉病变的诊断和治疗有较高的临床应用价值,可以提高介入治疗的安全性和成功率.     

双源CT大螺距技术在婴幼儿完全性肺静脉异位引流诊断中的应用

目的探讨双源CT(dual-source CT,DSCT)低剂量大螺距技术在婴幼儿完全性肺静脉异位引流(total anomalous pulmonary venous connection,TAPVC)诊断中的应用价值。方法回顾性分析我院10例TAPVC婴幼儿患者的临床资料,所有患儿术前行前瞻性心电门控下DSCT大螺距血管成像,均经手术治疗证实。由两位放射科医师按4分法对CT图像质量进行主观评价,同时记录辐射剂量。定量数据表示为平均数±标准差,分类数据表示为比例和百分比。观察者之间图像质量主观评分的一致性通过使用Kappa检验进行评估。结果所有患儿的CT图像均为可诊断图像,主观评分为2.7±0.7(2~4分),两位医师的评价一致性好(k=0.79)。10例TAPVC诊断及分型均和手术结果一致,包括心上型6例、心内型2例、心下型2例。平均剂量长度乘积及有效辐射剂量分别为(10.8±4.3)mGy·cm和(0.26±0.08)mSv。结论 DSCT低剂量大螺距技术是一种可靠的诊断婴幼儿TAPVC的检查方法,能为术前提供很好的参考依据。     

Coronariografía mediante tomografía computarizada con sincronización prospectiva. Comparación de la calidad de imagen y dosis de radiación con equipos de 128 detectores de fuente única y doble fuente

Objective

To compare the image quality and radiation dose in a group of patients undergoing coronary CT angiography using a 128-slice dual source helical CT scanner with high pitch alto and prospective acquisition with those in a group of patients with similar clinical characteristics undergoing coronary CT angiography using a 128-slice single-source CT scanner with prospective sequential acquisition.

Material and methods

We included 80 patients with heart rates ≤65 beats/min: 40 underwent sequential 128-slice single source CT with prospective synchronization and the other 40 underwent 128-slice dual source helical CT with high pitch and prospective synchronization. Two radiologists independently assessed the quality of the images of the coronary arteries on the 80 coronary CT angiograms: image quality was classified on a four-point scale in which 1 represented excellent and 4 deficient. The effective dose of radiation was also calculated.

Results

The clinical characteristics of the patients in the two groups were similar. The image quality obtained with dual source CT was significantly better than that obtained with single source CT (P=0.006). The mean effective dose of radiation in the group undergoing dual source CT was 36% lower than in the group undergoing single source CT (1.4±0.6 mSv vs. 2.2±0.9 mSv; P<0.01).

Conclusion

Although both sequential 128-slice single source CT with prospective acquisition and 128-slice dual source helical CT with high pitch and prospective acquisition provide good image quality and low effective doses of radiation, 128-slice dual source helical CT with prospective acquisition provides better image quality and results in a lower effective dose of radiation.     

CTA在主动脉夹层诊断及临床分型中的应用

目的 探讨多层螺旋CT血管成像（CTA）对主动脉夹层的诊断及临床分型中的价值。方法回顾分析20例主动脉夹层患者均行多层螺旋CT胸腹主动脉联合扫描并进行最大密度投影（MIP）、多平面重建（MPR）、容积重建（VRT）等后处理。结果20例均较好地显示了真假腔和主动脉夹层内膜瓣,显示破121位置18例,显示分支血管受累情况16例,按DeBakey分型：Ⅰ型8例,Ⅱ型1例,Ⅲ型11例。出现胸腔积液9例,出现心包积液1例。结论多层螺旋CTA是诊断主动脉夹层首选的无创性检查方法,并能提供准确的临床分型,对临床治疗具有重要的指导意义。     

MR evaluation of chronic aortic dissection

Thirty patients with suspected or known chronic aortic dissection were imaged with magnetic resonance (MR), CT, and angiography. Five of these patients had previously undergone surgical repair of the ascending aorta for a type A dissection. Magnetic resonance demonstrated an intimal flap and a double lumen in 25 cases. In four cases with a thrombosed false lumen, proved angiographically, an intimal flap and double channel were not seen. In two of four aortic dissections with a thrombosed false lumen, CT made the diagnosis by showing displaced intimal calcifications not visualized on MR. In one case the aortic dissection was made on CT and angiography but was not supported by MR which showed an aortic aneurysm, subsequently confirmed at surgery. Magnetic resonance, CT, and aortography differentiated between type A (nine patients) or B (20 patients) dissection in all cases and demonstrated extension into the abdominal aorta. Extension into the iliac arteries was seen on MR in three patients but missed in nine patients. Magnetic resonance differentiated the true and false lumen in all but one case. Thrombosis of the false channel was identified in four cases by a decrease in signal intensity on the second echo image. Cardiac gating and longitudinal contiguous sections seemed to be more suitable for appreciation of the relationships with arch vessels. Transverse contiguous slices allowed determination of the origin of celiac, mesenteric, and renal arteries from either the true or the false lumen. This study confirms that MR is an accurate and noninvasive method for the evaluation and follow-up of chronic aortic dissection, obviating the need for iodinated contrast media.     

主动脉夹层支架置入术前CT的诊断价值(附9例报告)

目的:探讨主动脉夹层行支架置入术前CT检查的诊断价值及对手术的指导意义.方法:回顾性分析9例主动脉夹层患者的支架置入术及CT影像资料,分析术前CT对支架置入术的指导作用及手术对CT的诊断要求.结果:主动脉夹层支架置入术前行CT平扫、增强及三维重建可较准确地反映主动脉夹层的分型、内膜裂口、周围脏器血供等情况.根据术前CT诊断信息设计手术,8例手术成功,1例术中发现病情发展而中止手术.结论:CT可较准确地诊断主动脉夹层,并为支架置入术提供重要信息.     

Time-resolved CT angiography in aortic dissection

Objectives

We performed this study to assess feasibility and additional diagnostic value of time-resolved CT angiography of the entire aorta in patients with aortic dissection.

Materials and methods

14 consecutive patients with known or suspected aortic dissection (aged 60 ± 9 years) referred for aortic CT angiography were scanned on a dual-source CT scanner (Somatom Definition Flash; Siemens, Forchheim, Germany) using a shuttle mode for multiphasic image acquisition (range 48 cm, time resolution 6 s, 6 phases, 100 kV, 110 mAs/rot). Effective radiation doses were calculated from recorded dose length products. For all phases, CT densities were measured in the aortic lumen and renal parenchyma. From the multiphasic data, 3 phases corresponding to a triphasic standard CT protocol, served as a reference and were compared against findings from the time-resolved datasets.

Results

Mean effective radiation dose was 27.7 ± 3.5 mSv. CT density of the true lumen peaked at 355 ± 53 HU. Compared to the simulated triphasic protocol, time-resolved CT angiography added diagnostic information regarding a number of important findings: the enhancement delay between true and false lumen (n = 14); the degree of membrane oscillation (n = 14); the perfusion delay in arteries originating from the false lumen (n = 9). Other additional information included true lumen collapse (n = 4), quantitative assessment of renal perfusion asymmetry (n = 2), and dynamic occlusion of aortic branches (n = 2). In 3/14 patients (21%), these additional findings of the multiphasic protocol altered patient management.

Conclusions

Multiphasic, time-resolved CT angiography covering the entire aorta is feasible at a reasonable effective radiation dose and adds significant diagnostic information with therapeutic consequences in patients with aortic dissection.     

Four- and Eight-Channel Aortoiliac CT Angiography: A Comparative Study

Purpose To compare performance parameters, contrast material load and radiation dose in a patient cohort having aortoiliac CT angiography using 4- and 8-channel multidetector CT (MDCT) systems.Methods Eighteen patients with abdominal aortic aneurysms underwent initial 4-channel and follow-up 8-channel MDCT angiography. Both the 4- and 8-channel MDCT systems utilized a matrix detector of 16 × 1.25 mm rows. Scan coverage included the abdominal aorta and iliac arteries to the level of the proximal femoral arteries. For 4-channel MDCT, nominal slice thickness and beam pitch were 1.25 mm and 1.5, respectively, and for 8-channel MDCT they were 1.25 mm and 1.35 or 1.65 respectively. Scan duration, iodinated contrast material load and mean aortoiliac attenuation were compared retrospectively. Comparative radiation dose measurements for 4- and 8-channel MDCT were obtained using a multiple scan average dose technique on an abdominal phantom.Results Compared with 4-channel MDCT, 8-channel MDCT aortoiliac angiography was performed with equivalent collimation, decreased contrast load (mean 45% decrease: 144 ml versus 83 ml of 300 mg iodine/ml contrast material) and decreased acquisition time (mean 51% shorter: 34.4 sec versus 16.9 sec) without a significant change in mean aortic enhancement (299 HU versus 300 HU, p > 0.05). Radiation dose was 2 rad for the 4-channel system and 2/1.5 rad for the 8-channel system at 1.35/1.65 pitch respectively.Conclusion Compared with 4-channel MDCT, aortoiliac CT angiography with 8-channel MDCT produces equivalent z-axis resolution with decreased contrast load and acquisition time without increased radiation exposure.     

Dual source multidetector CT-angiography before Transcatheter Aortic Valve Implantation (TAVI) using a high-pitch spiral acquisition mode

Objectives

Transcatheter Aortic Valve Implantation (TAVI) is an alternative to surgical valve replacement in high risk patients. Angiography of the aortic root, aorta and iliac arteries is required to select suitable candidates, but contrast agents can be harmful due to impaired renal function. We evaluated ECG-triggered high-pitch spiral dual source Computed Tomography (CT) with minimized volume of contrast agent to assess aortic root anatomy and vascular access.

Methods

42 patients (82?±?6?years) scheduled for TAVI underwent dual source (DS) CT angiography (CTA) of the aorta using a prospectively ECG-triggered high-pitch spiral mode (pitch?=?3.4) with 40?mL iodinated contrast agent. We analyzed aortic root/iliac dimensions, attenuation, contrast to noise ratio (CNR), image noise and radiation exposure.

Results

Aortic root/iliac dimensions and distance of coronary ostia from the annulus could be determined in all cases. Mean aortic and iliac artery attenuation was 320?±?70 HU and 340?±?77 HU. Aortic/iliac CNR was 21.7?±?6.8 HU and 14.5?±?5.4 HU using 100?kV (18.8?±?4.1 HU and 8.7?±?2.6 HU using 120?kV). Mean effective dose was 4.5?±?1.2?mSv.

Conclusions

High-pitch spiral DSCTA can be used to assess the entire aorta and iliac arteries in TAVI candidates with a low volume of contrast agent while preserving diagnostic image quality. Key Points ? Transcatheter Aortic Valve Implantation (TAVI) offers an alternative to surgical valve replacement in high risk patients. ? Such procedures require essential information about aortic root anatomy and vascular access. ? High pitch ECG-triggered dual source Computed Tomography (CT) can provide this information ? Sufficient image quality can be maintained even with low volumes of contrast agent and reduced x-ray exposure.     

Clinical utility of ultra high pitch dual source thoracic CT imaging of acute pulmonary embolism in the emergency department: Are we one step closer towards a non-gated triple rule out?

Objectives/Purpose

Aim of this study was to retrospectively compare the image quality and the radiation dose of an ultra high pitch CT scan for the evaluation of pulmonary embolism and visualization of cardiac structures in comparison to our institution's standard pulmonary embolism protocol.

Method and materials

The study cohort consisted of 115 consecutive patients, 57 underwent CT pulmonary angiography on a dual source 128 slice scanner (Siemens Somatom Definition FLASH) via an ultra high pitch mode (Pitch 2.8) while 58 were scanned on a dual source 64 slice scanner (Siemens Somatom Definition Dual Source) with standard pitch (Pitch 0.9). Qualitative image assessment was determined by two blinded radiologists with 3 and 15 years’ experience in chest and cardiac CT. Quantitative image assessment was determined by the signal to noise ratio (SNR) and contrast to noise ratio (CNR). Effective radiation dose was calculated via the product of the dose length product.

Results

For the ultra high pitch protocol, 14% (8/57) were positive for pulmonary embolus compared to 13.7% (8/58) for the standard pitch group. 98.2% of the ultra high pitch scans were diagnostic for pulmonary embolus vs. 94.8% of the standard protocol. Visualization of cardiac structures was significantly improved with the ultra high pitch protocol (p < 0.0001). Significantly more lung parenchymal motion was observed on the standard protocol (p < 0.0001). The mean pulmonary vessel attenuation, SNR, and CNR were not significantly different. The mean effective dose was lower for the ultra high pitch studies (4.09 mSv ± 0.78 vs. 7.72 mSv ± 2.60, p < 0.0001).

Conclusion

Ultra high pitch CT imaging for pulmonary embolus is a technique which has potential to assess motion free evaluation of most cardiac structures and proximal coronary arteries at lower radiation doses.