双能量减影自动去骨技术在双源CT颈动脉成像中的临床应用

目的探讨双源CT双能量减影中自动去骨技术在颈动脉成像中的临床应用价值。方法对65例临床拟诊颈动脉狭窄的患者,行双源CT颈部血管成像,分析双能量减影自动去骨技术对颈动脉病变的显示,并评价图像质量。结果 65例中3例血管正常变异,33例未见明显病变,血管主干及其分支显示清楚。32例颈动脉粥样硬化,其中4例支架植入术后。双能量CTA对颈根段、颅外段及颅底段血管的满意显示率分别为67.2%、96.2%及66.2%;3个部位血管原始评分比较差异有统计学意义(P=0.000);进一步两两比较,颈根段和颅底段血管的评分差异无统计学意义(P=0.181)。结论双源CT双能量减影成像是一种快速、简便、无创性检查方法,其整体去骨效果较好,血管显示效果最好者是颈动脉颅外段(颈总动脉和颈内动脉颅外段)。     

双源CT双能量去骨技术在颈动脉狭窄病变中的应用价值

目的:探讨双源CT双能量去骨技术在颈动脉钙化性狭窄病变中的应用价值。方法:回顾性分析18例颈动脉钙化性狭窄患者的病例资料,根据北美症状性颈动脉内膜切除试验(NASCET)标准评价血管的狭窄程度,分析颈动脉双能量去骨技术去除钙化斑块后的图像与DSA图像在量化分析颈动脉狭窄程度上的相关性。以DSA图像为对照,评价双能量去骨技术诊断钙化性颈动脉狭窄的敏感性、特异性、准确性、阳性和阴性预测值。结果:64段有明显致密钙化斑块的颈动脉血管,双能量去骨技术检出54个血管节段狭窄,DSA检出50个血管节段狭窄,两者对于颈动脉钙化性狭窄病变的检出差异无统计学意义(P>0.05),两者对于狭窄程度的分级相关性好(R2=0.913)。以DSA为对照,双能量去骨技术检出颈动脉狭窄的敏感度为98.0%,特异度为100.0%,符合率为90.6%,阳性预测值为90.7%,阴性预测值为90.0%。结论:采用双能量去骨技术去除钙化斑块可以很好地评价颈动脉钙化性狭窄病变。     

双源CT双能量去骨技术在头颈部血管成像中的应用

目的：比较双能量去骨与减影去骨对头颈部血管CT成像（CTA）的差异,探讨头颈部双能量CT血管成像（DECTA）的应用价值。方法：50例患者行DECTA检查并行双能量去骨,对照组45例患者使用减影CTA检查并去骨,然后分别比较DECTA和减影CTA的图像质量、去骨所用时间及放射剂量,并观察DECTA上颈总动脉分叉处钙化的显示效果。结果：颅内动脉DECTA和减影CTA的图像质量差异无显著性意义（Z=0.790,P=0.430）,颈内动脉虹吸段和岩段DECTA图像质量优于减影CTA（虹吸段Z=-1.989,P=0.047;岩段Z=-2.014,P=0.044）,而减影CTA显示颈根部动脉优于DECTA（Z=3.900,P〈0.001）。同时DECTA减少约24.0%的放射剂量。DECTA上共有28例发现有血管性病变,所有病变显示清晰,其中10例并与DSA或外科手术对照具有良好的一致性。颈总动脉分叉处36个钙化灶中有8个钙化灶未在DECTA上显示。结论：DECTA显示头颈部血管总体良好,成功率高,且放射剂量明显减少,但对于颈根部动脉显示仍存在一定局限。     

双源CTA在颅内动脉瘤中的应用价值

目的:探讨双源CT血管造影(DSCTA)在颅内动脉瘤中的临床应用价值.方法:22例颅内动脉瘤患者行双源CTA检查,分别对双能量去骨法与常规法获得的重建图像按0～5级进行质量评分并记录后处理时间,进行配对样本t检验.以DSA为标准,,评估DSCTA的敏感性、特异性.结果:共检出动脉瘤30个.双能量法平均后处理时间明显少于常规法(6.85±1.38min vs 13.20±2.02min,P<0.01).图像质量评分分别为4.35±0.50和3.23±0,36,有统计学显著性差异(P<0.05).与DSA对照,双能量法和常规法检出率分别为100%和85.7%.按动脉瘤个数计算,DSCTA的敏感性为93.4%,特异性为100%.结论:双源CT的双能量CTA与DSA有高度一致性,可替代DSA而成为颅内动脉瘤筛选及术后随访的首选检查方法.     

双能量CT血管造影在下肢动脉旁路移植术后随访中的应用

目的探讨双能量 CT 血管造影在下肢动脉旁路移植术后随访中的应用价值.资料与方法10例下肢动脉旁路移植术后患者接受双源 CT 双能量血管造影检查,所获得的数据在双能去骨软件中去除钙化及骨质,再在3D 软件中进行最大密度投影及容积再现重建,结合原始图像对移植血管进行评价.结果双能量CT 血管造影显示10例患者移植血管清晰,管腔通畅,位置及形态正常,连接处以远血流部分恢复,达到临床诊断要求.结论双能量 CT 血管造影可清晰显示人工移植血管的位置及形态,可作为下肢动脉病变人工血管旁路移植术后随访的检查方法.     

双能量CT去除颅骨和硬化斑块定量分析钙化颈动脉狭窄的应用及与数字减影血管造影的对照性研究

本研究对双能（DE）CTA和双能去除颅骨和硬化斑块（DE硬化斑块去除）定量钙化性颈动脉狭窄进行了评价,并将其结果与数字减影血管造影（DSA）结果进行了对照。18条有致密钙化的狭窄颈动脉血管（13例）接受了双源CT的双能量模式（管电压140kV和80kV）检查。采用商用软件从双能量影像上去除颅骨和硬化斑块。     

双源CT在头颈部血管造影中的应用

目的：探讨双源CT（DSCT）在头颈部血管造影中的临床应用价值。方法：搜集126例疑为头颈部血管病变的患者,行双源CT头颈部血管造影,应用MIP、VR及双能量（DE）去骨等后处理技术进行重建。其中32例经DSA或手术证实。结果：126例均获得高质量图像,除11例阴性及15例正常变异之外,发现血管异常100例（动脉狭窄71例,动脉闭塞17例,动脉瘤9例,Sturge-Weber综合症2例,左颈内动脉缺如、发育性静脉异常、大动脉炎及Moyamoya病各1例）。检查结果与DSA基本一致。所有病例均可清晰显示脑血管主干及其Ⅰ～Ⅱ级分支,其中119例可显示大脑中动脉Ⅳ～Ⅴ级分支。结论：DSCT头颈部血管造影作为无创性检查技术,对于头颈部血管病变的诊断具有较高的临床价值。     

炫速CT双能量与常规减影血管成像在诊断颅内血管病变显示的对比研究

目的 对双能量直接去骨减影法(Dual-Energy CTA)与常规减影法(Neuro-DSA)在脑动脉成像的图像质量、患者接受辐射剂量及图像处理效率及检查成功率方面进行比较,探讨两种减影方法的差异.方法 根据投照技师操作习惯不同,将连续120名接受头颅CTA检查的患者随机分为双能量扫描组和常规扫描组,采用SIMENS SOMATOMDefinition Flash CT机分别以双能量模式及常规模式进行扫描.结果 双能量减影法与常规减影法对图像质量无明显影响,辐射剂量明显低于常规减影,降低率为44％,图像处理效率及检查成功率均明显高于对照组,差异具有统计学意义(t=1.66,P＜0.01).结论 双能量直接去骨减影法具有辐射剂量低,图像质量清晰,图像处理快,检查成功率高的优势,具有广阔的应用前景,值得推广应用.     

多层螺旋CT颈动脉血管成像技术与临床应用初步探讨

目的分析颈血管疾病多层螺旋CT(multislicespiralCT,MSCT)影像学特征,并初步评价其临床应用价值。方法本组研究共搜集80例行颈动脉血管成像检查的患者,其中15例同时行DSA检查。分析MSCTA图像质量;比较同1例患者的CTA及DSA结果,评价SCTA诊断颈动脉狭窄的准确性。比较几种CTA后处理方法对管壁钙化显示情况并进行统计学分析。结果本组15例共计60支颈/椎动脉与同期DSA结果进行对照。MSCTA诊断颈/椎动脉狭窄的敏感度89.5%,特异度92.7%,阴性预测值95%,Kappa值0.81。同时,最大密度投影(MIP)、容积重建(VR)等技术能较好显示颈脉动脉管壁钙化情况,较易获得满意图像质量。结论多层螺旋CT血管成像技术作为一种无创性检查颈部血管疾病的方法,有望作为诊断此类疾病的首选检查手段。     

Flash双源CT脑血管成像双能量减影去骨比率值的优化研究

目的 探讨双能量减影去骨比率值的调节在脑血管成像中的临床应用价值.方法 回顾分析45例双源CT二期双能量脑血管检查患者资料.双能量法按不同去骨比率(Ratio)值分别分成A组(Ratio=1.6),B组(Ratio=1.7),C组(Ratio=1.8),D组(Ratio=1.9,默认值);100 kV Neuro-DSA减影法定为E组.采用双盲法按去骨程度及血管完整程度对图像质量评分(1~5分,1分为差,5分为优,3~5分为满意).通过自身对比分析不同双能量去骨Ratio值对减影图像质量的影响,并以Neuro-DSA减影为对照,比较各组图像信噪比(SNR)、对比噪声比(CNR)及图像质量评分的统计学差异.结果 双能量减影不同去骨Ratio值组的颅底动脉图像评分总体满意率分别为:A组73.33%,B组91.11%,C组78.52%,D组70.37%.Ratio值取1.7时,虹吸段及岩骨段动脉的评分达满意显示率最高,差异有统计学意义(P<0.05).B组、D组、E组3组间SNR与CNR的差异不显著(P>0.05).结论 双源CT单次增强双能量减影去骨Ratio值的调节优化后的图像质量与100 kV Neuro-DSA减影一致性较好,可弥补双能量减影颅底脑血管缺损的不足,推荐在临床急诊脑血管检查中应用.     

The utilization of dual source CT in imaging of polytrauma

Despite the growing role of imaging, trauma remains the leading cause of death in people below the age of 45 years in the western industrialized countries. Trauma has been touted as the largest epidemic in the 20th century. The advent of MDCT has been the greatest advance in trauma care in the last 25 years. However, there are still challenges in CT imaging of the polytrauma individual including time restraints, diagnostic errors, radiation dose effects and bridging the gap between anatomy and physiology. This article will analyze these challenges and provide possible solutions offered by the unique design of the dual source CT scanner.     

Comparison of dual photon and dual energy X-ray bone densitometers in a clinic setting

In clinical practice, decisions must be made about whether and how to convert to newer technologies. To address this issue, two separate studies were conducted. We evaluated the relationships between results of lumbar spine measurements using two dual photon absorptiometry (DPA1 and DPA2) instruments and one dual energy X-ray (DXA) instrument with the same subjects (49 volunteers), and also in 65 patients who were measured on the DPA1 and DXA machines. Second, we measured the lumbar spine and the proximal femur in three groups of 12 female volunteers three times on one instrument within 1 week. We purposely simulated a busy clinic setting with different technologists, older radioactive sources, and a heterogeneous patient group. The comparison study indicated a significant difference between the mean bone density values reported by the machines, but the results were highly correlated (R ² = 0.89–0.96). The short-term precision errors (coefficients of variation) differed among the instruments, ranging from 1.3% (DXA of the spine) to 5.1% (DPA1 of the spine), and in the femoral neck, 2.3% and 2.4% (DXA and DPA1, respectively) versus 3.5% by DPA2. This study emphasizes the differences between instruments, the potential for greater error in busy clinic environments, and the apparent superiority of dual energy X-ray absorptiometry under these less than ideal conditions.     

Virtual unenhanced second generation dual-source CT of the liver: Is it time to discard the conventional unenhanced phase?

Introduction

Dual-energy dual source CT can almost simultaneously image patients using two different tube potentials, allowing material decomposition and creation of ‘virtual unenhanced’ (VU) images from post-contrast series.

Methods

75 patients undergoing triple-phase liver CT examinations were imaged using a second generation dual-source CT machine with tube potentials 140/100 kVp. Post-processing VU series were derived from arterial and portal phases. Regions-of-interest from liver parenchyma and within fat (‘noise’ assessment) were drawn to compare VU series to conventional unenhanced (CU) series. Subjective analysis assessed image quality and the suitability of VU to replace CU series.

Results

Mean Hounsfield unit (HU) values of liver were higher in the VU series: portal 51.9 (SD = 10.29), arterial 51.1 (SD = 10.05), compared to the CU series 49.2 (SD = 9.11); P < 0.001. However, Pearson's correlation of the VU and CU series remained excellent: 0.838 (portal), 0.831 (arterial). Bland–Altman plots also showed good agreement between both VU and the CU datasets. Noise measurements were significantly lower in both VU series (P < 0.001). For subjective analysis, image quality was rated as very good/excellent in 100% of CU images, 93.3% of portal VU and 88.7% of arterial VU series. Overall, portal VU and arterial VU images were acceptable replacements for the CU series in 97.4% and 96.1%, respectively. Post-processing was noted to create a number of artefacts in VU images – knowledge of these is essential for interpretation.

Conclusions

Portal and arterial-derived VU images objectively correlate to CU images and demonstrate good image quality and acceptability. VU image sets could replace the conventional unenhanced images in the vast majority of cases, significantly reducing radiation dose.     

Comparative study of the performances of X-ray and gadolinium 153 bone densitometers at the level of the spine,femoral neck and femoral shaft

We investigated the precision of gadolinium 153 dual photon absorptiometry (DPA) and quantitative digital radiography (QDR) bone densitometers by determining in vitro and in vivo coefficients of variation (CV) of bone mineral density (BMD). In vitro, the long-term CV of spine phantom BMD measured weekly for 40 weeks was 1.2% and 0.7% for DPA and QDR, respectively. Simulating soft-tissue thickness with water, the CV of 6 repeat measurements of spine phantom at depths from 0 to 27 cm in 1 cm steps (a total of 168 measurements) increased from 0.1 % at 0 cm of water to 2.5% at 27 cm for DPA, and from 0.2% at 0 cm to 1.4% at 27 cm for QDR; mean CV of the 28 series (0–27 cm) was higher for DPA (1.2%±0.8%, mean±SD) than for QDR (0.7%±0.6%;P<0.001). With the hip phantom, femoral neck BMD was determined, and the CV was also dependent on water thickness; mean CV of the 20 series (0–10 cm) was 2.1%±1.2% for DPA and 1.3%±0.9% for QDR (not significant). In vivo, at the spine level, with DPA, mean CV of BMD measured 6 times after repositioning in 6 healthy volunteers was 3.8%±1.9% and 2.1%±0.7% with¹⁵³Gd activity of 0.46Ci and 1 Ci, respectively (BMD range: 0.796 1.247 g/cm², no significant difference between the two groups). Both values were significantly higher (P < 0.05) than mean CV with QDR: 1.0%±0.5% (12 subjects, same conditions; BMD range: 0.811–1.124 g/cm², no significant difference with the two previous groups). At the femoral neck and shaft levels, the mean CV observed with QDR tended to be lower as compared with DPA (not significant). At the three sites, BMD values obtained with DPA and QDR in 62 patients were highly correlated. In conclusion, our results indicate that the higher precision obtained with QDR is particularly significant at the lumbar spine level, but large biological variations in soft tissue thickness can still influence the degree of precision of BMD measurement.     

低剂量与常规剂量对比剂双能量肺灌注图像质量对比分析

目的:探讨对比剂剂量对双源CT双能量肺灌注成像质量的影响.方法:疑肺动脉栓塞患者行双源CT双能量肺灌注扫描,30例使用低剂量(0.7ml/kg)对比剂,30例使用常规剂量对比剂(1.5ml/kg),注射速率均为4.5ml/s.扫描后同时获得肺动脉CTA及肺灌注图像.测量左、右叶肺动脉干及各肺叶动脉增强后的CT值,对比分析两组间增强后的CT值.判断肺灌注图像质量并分级,比较两组的肺灌注图像质量差异.结果:低剂量组与常规剂量组左、右叶肺动脉干及各肺叶动脉增强后的CT值无明显差异(P＞0.05).肺段及亚段肺动脉图像清晰显示.低剂量组肺灌注图像大部分信号均匀(26/30),常规剂量组肺灌注图像大部分信号均匀(24/30).常规剂量组上腔静脉、右心房高密度对比剂所致灌注伪影明显多于低剂量组(48:10).结论:低剂量与常规剂量双能量肺灌注成像的肺动脉图像质量无明显差异,降低对比剂剂量可以减少双能量肺灌注图像的伪影.     

Use of novel photon – counting detector CT for diagnosis of bowel infarction

A 75 year old male with a history of thoraco-abdominal surgery presented with acute onset epigastric pain. CT of the abdomen and pelvis with contrast performed on a novel photon-counting detector CT demonstrated dilated loops of small bowel herniating into the thoracic cavity through a defect in the left hemidiaphragm. On conventional CT reconstructions, the bowel wall demonstrated a thin rim of hyper-density which could have been interpreted as normal mucosal enhancement in viable bowel. However, spectral-imaging data including the iodine map revealed a complete lack of enhancement within the herniated loops of bowel compatible with infarction. With the added diagnostic information, the patient was taken rapidly to surgery for small bowel resection, with good outcome.     

Adenosine-stress dynamic real-time myocardial perfusion CT and adenosine-stress first-pass dual-energy myocardial perfusion CT for the assessment of acute chest pain: Initial results

Purpose

Recent innovations in CT enable the evolution from mere morphologic imaging to dynamic and functional testing. We describe our initial experience performing myocardial stress perfusion CT in a clinical population with acute chest pain.

Methods and materials

Myocardial stress perfusion CT was performed on twenty consecutive patients (15 men, 5 women; mean age 65 ± 8 years) who presented with acute chest pain and were clinically referred for stress/rest SPECT and cardiac MRI. Prior to CT each patient was randomly assigned either to Group A or to Group B in a consecutive order (10 patients per group). Group A underwent adenosine-stress dynamic real-time myocardial perfusion CT using a novel “shuttle” mode on a 2nd generation dual-source CT. Group B underwent adenosine-stress first-pass dual-energy myocardial perfusion CT using the same CT scanner in dual-energy mode. Two experienced observers visually analyzed all CT perfusion studies. CT findings were compared with MRI and SPECT.

Results

In Group A 149/170 myocardial segments (88%) could be evaluated. Real-time perfusion CT (versus SPECT) had 86% (84%) sensitivity, 98% (92%) specificity, 94% (88%) positive predictive value, and 96% (92%) negative predictive value in comparison with perfusion MRI for the detection of myocardial perfusion defects. In Group B all myocardial segments were available for analysis. Compared with MRI, dual-energy myocardial perfusion CT (versus SPECT) had 93% (94%) sensitivity, 99% (98%) specificity, 92% (88%) positive predictive value, and 96% (94%) negative predictive value for detecting hypoperfused myocardial segments.

Conclusion

Our results suggest the clinical feasibility of myocardial perfusion CT imaging in patients with acute chest pain. Compared to MRI and SPECT both, dynamic real-time perfusion CT and first-pass dual-energy perfusion CT showed good agreement for the detection of myocardial perfusion defects.     

Dual energy CTA of the supraaortic arteries: Technical improvements with a novel dual source CT system

Objectives

Computed tomography angiography (CTA) is a well-accepted imaging modality to evaluate the supraaortic vessels. Initial reports have suggested that dual energy CTA (DE-CTA) can enhance diagnosis by creating bone-free data sets, which can be visualized in 3D, but a number of limitations of this technique have also been addressed. We sought to describe the performance of DE-CTA of the supraaortic vessels with a novel dual source CT system with special emphasis on image quality and post-processing related artifacts.

Materials and methods

Thirty-three patients underwent carotid CT angiography on a second generation dual source CT system. Simultaneous acquisitions of 100 and 140 kV data sets in arterial phase were performed. Two examiners evaluated overall bone suppression with a 3-point scale (1 = poor; 3 = excellent) and image quality regarding integrity of the vessel lumen of different vessel segments (n = 26) with a 5-point scale (1 = poor; 5 = excellent), CTA source data served as the reference.

Results

Excellent bone suppression could be achieved in the head and neck. Only minor bone remnants occurred, mean score for bone removal was 2.9. Mean score for vessel integrity was 4.3. Eight hundred fifty-seven vessel segments could be evaluated. Six hundred thirty-five segments (74%) showed no lumen alteration, 65 segments (7.6%) lumen alterations <10%, 27 segments (3.1%) lumen alterations >10% resulting in a total luminal reduction <50%, 17 segments (2%) lumen alterations of more than 10% resulting in a total luminal reduction >50%, and 113 segments (13.2%) showed a gap in the vessel course (100% total lumen reduction). Artificial gaps of the vessel lumen occurred in 28 vessel segments due to artifacts caused by dental hardware and in all but one (65) ophthalmic arteries.

Conclusions

Excellent bone suppression could be achieved, DE imaging with 100 and 140 kV lead to improved image quality and vessel integrity in the shoulder region than previously reported. The ophthalmic artery still cannot be adequately visualized.