等渗低浓度对比剂肺动脉CT血管成像临床应用研究

【摘要】目的：评估等渗低浓度对比剂在肺动脉CT血管成像（CTPA）中应用的可行性。方法：临床疑似肺动脉栓塞行CTPA检查的患者60例,随机等分为低浓度组和对照组。低浓度组和对照组对比剂分别为碘克沙醇40mL（270mg I/mL）或碘普胺40mL（370mg I/mL）。对两组的图像质量评分、平均CT值、噪声值、图像信噪比(SNR)、对比噪声比(CNR)、容积CT剂量指数(CTDIvol)和剂量长度乘积(DLP)进行正态分布检验,符合正态分布则应用独立样本t检验,不符合正态分布则使用秩和检验,应用χ2检验比较两组间上腔静脉硬化伪影显示率和肺动脉栓塞诊断阳性率差异。结果：低浓度组和对照组受试者的年龄、性别、身高、体重及BMI差异均无统计学意义。两组图像质量评分、腔静脉评分、肺动脉主干及左、右干平均CT值、噪声、SNR及CNR差异均无统计学意义（P>0.05）。低浓度组上腔静脉CT值低于对照组,差异有统计学意义（P<0.05）。低浓度组的辐射剂量CTDIvol和DLP与对照组相比差异无统计学意义（P>0.05）。结论：等渗低浓度对比剂CTPA图像质量满足诊断要求,减少了患者碘负荷。     

低浓度低剂量对比剂宝石能谱CT肺动脉成像的初步研究

目的:探讨应用低浓度、低剂量对比剂宝石能谱CT肺动脉成像的可行性.方法:60例临床拟诊为肺动脉栓塞(PE)的患者随机分成两组,每组30例,行CT肺动脉血管成像(CTPA)检查.A组为常规组,使用浓度为370 mg I/mL的对比剂碘帕醇,用量为60 mL,扫描管电压为120 kVp.B组为能谱组,使用浓度为300 mg I/mL的对比剂碘帕醇,用量为20 mL,扫描方式为能谱模式(GSI).比较常规组和能谱最佳单能量组肺动脉CT值、图像背景噪声、信噪比(SNR)、对比噪声比(CNR)、CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效辐射剂量(ED)及图像质量主观评分的差异.结果:B组肺动脉最佳单能量图像能量水平集中在63～68 keV.能谱组(7.5g)较常规组(24.0g)所用的碘总量明显下降,两组差异有统计学意义(P＜0.05).能谱最佳单能量组图像质量与常规组CTPA相比,两者肺动脉CT值、图像噪声、SNR、CNR、DLP、ED以及主观评分之间差异均无统计学意义(P＞0.05).结论:宝石能谱CT低浓度、低剂量对比剂CTPA检查,在降低人体碘摄入量的同时,能达到与常规120 kVp结合高浓度、常规剂量对比剂相当的图像质量,且辐射剂量未增加.     

自然呼吸下小剂量对比剂CTPA诊断肺动脉栓塞

目的:评估自然呼吸状态下小剂量对比剂CT肺动脉成像(CTPA)的可行性及诊断肺动脉栓塞的价值.方法:64例临床怀疑肺动脉栓塞的患者行CTPA检查,按随机表分为A、B两组:A组(n=32),自然呼吸状态下扫描,管电压100kV,螺距3.2,对比剂为碘海醇(350 mg I/mL)25 mL;B组(n=32),常规扫描模式,管电压120 kV,螺距2.2,对比剂为碘帕醇(370 mg I/mL).测量各级肺动脉CT值、标准差(SD)、上腔静脉CT值;计算肺动脉主干及双下肺动脉基底支信噪比(SNR)、对比噪声比(CNR);记录对比剂用量、容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效辐射剂量(ED),并进行统计学分析.结果:两组肺动脉各级分支CT值及两下肺动脉基底支SD值、SNR差异均无统计学意义(P＞0.05).A组肺动脉主干、左右肺动脉SD值高于B组,差异均有统计学意义(P＜0.05);A、B两组肺动脉主干SNR、CNR及左右下肺动脉基底支CNR差异均有统计学意义(P＜0.05).A组上腔静脉CT值[(469.93±196.22) HU]、对比剂用量(25.00mL)明显低于B组[(870.72±426.87)HU、(49.47±7.56)mL],差异有统计学意义(P＜0.01);A组CTDIvol、DLP、ED较B组明显减低[(2.81±3.86) vs (5.65±1.14),P=0.000;(86.25±0.40) vs (163.63±39.00),P=0.000;(1.21±0.18)mSv vs (2.29±0.55)mSv,P=0.000],差异均有统计学意义(P＜0.05).两组共检出肺动脉栓塞24例(A组11例,B组13例),两组间阳性显示率差异无统计学意义(P＞0.05);两组上腔静脉线束硬化伪影显示率(A组9例,B组19例)差异有统计学意义(P＜0.05).结论:自然呼吸状态下小对比剂用量CTPA检查图像质量可满足诊断要求,可减少上腔静脉线束硬化伪影,降低对比剂用量及辐射剂量.     

80kVp、低剂量对比剂结合ASIR重建在肺动脉CTA中的初步研究

目的探讨能谱CT采用80k Vp管电压、低剂量对比剂结合ASIR技术行CT肺动脉成像(CTPA)的可行性。方法 60例临床拟诊为肺动脉栓塞的患者,随机分成2组,每组30例,行CTPA检查。A组管电压为120k Vp,对比剂用量60ml,FBP技术重建。B组管电压为80k Vp,对比剂用量为20ml,50%ASIR技术重建。采用独立样本的t检验比较两组图像肺动脉CT值、图像背景噪声、信噪比(SNR)、对比噪声比(CNR)、CT剂量指数(CTDIvol)、剂量长度乘积(DLP)和有效剂量(ED)的差异。采用Mann-Whitney U检验比较两组图像主观评分差异。结果 B组肺动脉CT值、SNR、CNR均高于A组(P<0.05)。B组CTDIvol、DLP、ED均低于A组(P<0.05)。两组图像背景噪声、图像质量主观评分差异无统计学意义(P>0.05)。结论 80k Vp、低剂量对比剂结合ASIR技术行CTPA检查可获得较好的图像质量,满足临床诊断要求,同时降低人体辐射剂量及对比剂用量。     

双低技术在肺动脉血管CT造影中的应用研究

目的探讨低剂量60 kV管电压技术联合低剂量对比剂应用于肺动脉CT血管造影(CTPA)的可行性。方法纳入临床怀疑肺动脉栓塞要求行CTPA检查且体质量指数(BMI)< 25 kg/m2的门诊或住院患者60例, 按照随机数字表法分为对照组(采用常规剂量方案:100 kV管电压, 常规50 ml, 速率为4.5 ml/s的对比剂注射方案)或试验组(采用低剂量方案:60 kV管电压, 30 ml对比剂混合20 ml生理盐水, 速率为4.5 ml/s的对比剂注射方案)各30例。测量肺动脉干、左右肺动脉和左右肺叶下动脉的HU值, 计算信噪比(SNR)和对比噪声比(CNR), 评价客观图像质量, 并记录辐射剂量。主观图像质量由放射科医生根据总体图像质量及肺动脉增强均匀性用5分法进行评估。采用Mann-WhitneyU检验比较两组的噪声、SNR、CNR及辐射剂量, 采用χ2检验比较两组主观图像质量差异。结果所有图像均满足临床诊断要求。试验组与对照组CTPA图像主观总体图像质量差异无统计学意义(P > 0.05), 增强情况的评分差异无统计学意义(P > 0.05)。试验组与对照组在肺...     

对比剂不同注射速率在低剂量CT肺动脉成像中的应用

目的分析对比剂不同注射速率(碘普罗胺300mgI/ml)在低剂量CTPA成像中应用的可行性。方法纳入60例临床疑似肺动脉栓塞拟行CTPA检查的患者,随机数字表法分为A、B、C三组,每组各20例,A组注射速率为5ml/s,对比剂用量35ml,延迟时间采用团注测试法(bolus test);B、C两组注射速率分别为4ml/s、3.5ml/s,对比剂用量25ml,延迟时间采用团注追踪(bolus tracking)技术。三组均采用管电压80kV、固定毫安秒80mAs,iDose43级迭代重建算法重建。分别测量肺动脉主干及分支的CT值并计算其平均值,对三组图像的肺动脉平均CT值、信噪比(SNR)、对比噪声比(CNR)、主观图像质量评价、有效剂量(ED)等进行比较分析。结果随着注射速率的降低,三组图像肺动脉平均CT值依次降低,但肺动脉CT值均高于300HU,能满足临床诊断需要,且肺动脉平均CT值、SNR、CNR、ED、主观图像质量评价相比差异均无统计学意义(P>0.05)。结论采用3.5ml/s注射速率,25ml的对比剂用量,肺动脉CTPA低剂量成像质量不仅能满足诊断需要,而且降低了碘摄入量和碘流率(iodine delivery rate,IDR),有效地减少对比剂肾病及对比剂外渗风险,值得推广应用。     

肺动脉CT成像中不同扫描模式对影像质量及辐射剂量影响的对比研究

目的 探讨能谱CT扫描模式和不同噪声指数扫描模式在CT肺动脉成像(CTPA)中影像质量和辐射剂量的比较研究.方法 将体质量指数(BMI)为20～25 kg/m2的200例患者随机分成4组进行CTPA扫描,扫描范围为270～320 mm.第1组扫描模式为能谱CT扫描模式;第2～4组使用普通扫描模式,但噪声指数不同,分别为26、36、46,扫描参数为120 kV,自动管电流调制技术(Auto mA)和智能管电流调制技术(Smart mA);记录4组扫描模式的CTDIvol及DLP并取平均值,将DLP转换为有效剂量.计算上述扫描条件影像的信噪比(SNR)及对比度噪声比(CNR)并取平均值,请3位影像学专家对影像进行双盲法评分,用Kappa检验比较观察者评分的一致性;采用双因素方差分析比较4组患者的SNR、CNR、评分值及有效剂量.结果 不同扫描模式下4组扫描模式产生影像的SNR平均值分别为25.55 ±3.13、23.32±2.63、22.38±1.83、20.11 ±2.88;CNR平均值分别为27.71 ±3.78、25.91 ±2.38、24.87±3.38、24.28±2.36;3位影像学家对上述影像主观评价平均值分别为4.52±0.52、4.55±0.22、4.51 ±0.16、4.21 ±0.32;不同扫描模式的CTDIvol平均值分别为(17.77±2.26) mGy、(7.11±1.78) mGy、(6.07±1.16) mGy、(5.56±1.22) mGy;DLP平均值分别为(489.89±25.68) mGy、(235.69±20.68) mGy、(178.23±19.56)mGy、(160.08±19.67)mGy,并将DLP转换为有效剂量值分别为(7.33±0.36) mSv、(3.52±0.22) mSv、(2.67±0.31) mSv、(2.41 ±0.18)mSv.4组间影像的SNR和CNR值差异无统计学意义(F=4.52,P＞0.05),3名影像学专家的评分一致性较高(Kappa=0.859,P＜0.01);第4组的有效剂量较第1组低67.12％,二者间差异有统计学意义(F =29.56,P＜0.01);第4组的有效剂量较第2组低31.53％,二者间差异有统计学意义(F =23.32,P＜0.01).结论 CTPA能谱CT扫描模式和不同噪声指数(26、36、46)的普通扫描模式影像质量没有明显区别,普通扫描模式较能谱CT扫描模式的辐射剂量低;不同噪声指数扫描模式的影像质量没有明显区别,但其辐射剂量却有明显差别.     

迭代模型重建技术在肺动脉“双低”成像中的应用研究

目的：探讨迭代模型重建(IMR)技术在肺动脉低剂量、低对比剂成像中的应用价值。方法对60例临床怀疑肺动脉栓塞(PE)患者行256层螺旋CT肺动脉成像,根据随机表法将患者随机分为实验组、对照组,每组30例。实验组原始数据分别采用滤波反投射(FBP)、IMR技术重建图像(A、B组),对照组原始数据采用 FBP 重建(C 组)。采用5分制方法评价肺动脉主干及其分支的图像质量,测量并计算肺动脉强化值(CT 值)、图像噪声值、图像信噪比(SNR)、对比噪声比(CNR),记录 CT 容积剂量指数(CTDIvol)、剂量长度乘积(DLP),计算有效剂量(ED)。比较 A组与 B组,B组与 C组肺动脉 CT值、图像噪声、SNR、CNR 及主观图像质量。结果实验组与对照组体质量指数(BMI)差异无统计学意义(P=0.096)。实验组CTDIvol、ED低于对照组(P<0.001)。A、B组肺动脉CT值差异无统计学意义(P=0.999),B组肺动脉CT值高于C组(P=0.005)。B组图像噪声明显低于A组(P<0.001),B组图像噪声高于C组(P<0.001)。B组 SNR、CNR高于 A组(P<0.001),B、C组 SNR、CNR差异无统计学意义(P=0.831,P=0.958)。B组图像可诊断率、优良率高于 A组(P<0.001),B、C 2组图像优良率差异无统计学意义(P=1.000)。结论肺动脉“双低”成像扫描模式联合更优化的迭代重建技术的应用,能够保证图像质量的同时大幅度降低患者辐射剂量及对比剂应用。     

低剂量低浓度CT扫描技术在急性肺动脉栓塞CTPA的应用

目的探讨急性肺动脉栓塞患者应用CT低剂量、低浓度扫描技术的临床价值。方法将我院2014年1月~2015年8月拟诊断为急性肺动脉栓塞患者按照随机数字表法分组为对照组与观察组各50例,患者均进行CT肺动脉血管成像(CTPA)检查,其中对照组为常规组,采用120k V+350mg I/ml欧乃派克;观察组为低剂量组,采用100k V+270mg I威视派克;均为能谱模式(GSI)。统计两组肺动脉CT值、信噪比(SNR)、图像背景噪声、对比噪声比(CNR)、剂量长度乘积(DLP)、CT剂量指数(CTDIvol)及有效辐射剂量(ED),并评价两组图像质量评分。结果两组CTDIvol比较,P0.05;其余图像质量及辐射剂量参数比较,P0.05。两组图像质量评分比较,P0.05。结论应用CT低剂量、低浓度扫描技术诊断急性肺动脉栓塞可取得较好的图像质量且不会增加辐射剂量,因此值得推广。     

低管电压在降低肺动脉CT成像对比剂量及辐射剂量的研究

目的：探讨64排螺旋 CT 肺动脉成像(CTPA)与应用低管电压结合高管电流技术在 CTPA 中碘对比剂用量、辐射剂量及图像质量对比性的研究。方法随机将本院60例临床怀疑肺栓塞要求行 CTPA 分为3组：Ⅰ组20例,采用120 kV、180 mA,对比剂量为70 mL;Ⅱ组20例,采用100 kV、280 mA,对比剂量为50 mL;Ⅲ组20例,采用80 kV、自动管电流调制技术300~500 mA,对比剂量为30 mL。分别测量每组肺动脉3处中心区及1处段支的 CT 值和图像噪声;对2组图像的客观指标、主观图像质量评价、CT 容积剂量指数(CTDIvol)、剂量长度乘积(DLP)和有效剂量(ED)进行比较,以评价低 kV 结合高 mA、低对比剂量应用在MSCTPA 扫描中的可行性。使用方差分析及 t 检验对3组数据进行两两比较分析。结果与标准法的 CTPA 相比较,两低剂量组CTPA 在所有肺动脉干中均具有较好的显示,3组在5分图像质量评分差异无统计学意义(P >0.05),而3组 CT 值、噪声、信噪比(SNR)、对比噪声比(CNR)均有统计学意义(P <0.01)。Ⅱ组、Ⅲ组 CT 辐射剂量 CTDIvol、DLP 均低于Ⅰ组,差异有统计学意义(P <0.01)。结论在80 kV 扫描条件下采用小剂量对比剂预注射法与传统方法比较,降低对比剂量同时可明显减少上腔静脉内对比剂的硬化伪影对右肺动脉观察的干扰,有利于减轻患对比剂肾病的危险且降低了患者的辐射剂量。     

Virtual pulmonary arterioscopy in pulmonary embolic disease

16 slice multidetector CT provides virtual endoscopic views of the inside of arteries, or any other hollow structures. This is performed non-invasively using post-processing of three-dimensional isotropic image data sets, acquired during standard CT examinations. These virtual endoscopic views are simultaneously correlated with the standard multiplanar reconstructions, with the ability to navigate a virtual camera through the hollow structure under study. Normal and abnormal volume rendered images of the pulmonary arteries are presented in correlation with the multiplanar reformats. The abnormal images show the volume rendered appearances of acute and chronic pulmonary embolic disease. It is also postulated that this technique has a problem solving role in the differential diagnosis of chronic mural emboli from extravascular structures such as adjacent lymph nodes or bronchiolar impaction. This technique may also have a role in medical education, providing clinicians and medical students with interactive three-dimensional representations of disease processes.     

The relationship between pulmonary artery pressure and pulmonary artery diameter in pulmonary hypertension

The pulmonary arteries dilate in response to many factors, principally increased pressure and flow. In patients who have pulmonary arterial hypertension but no increase in flow, we have compared main pulmonary artery size at computed tomography with pulmonary haemodynamic data obtained during right heart catheterisation. In patients with primary pulmonary hypertension and chronic thromboembolic pulmonary hypertension, dilatation correlated with raised pulmonary vascular resistance and reduced cardiac output but not with mean arterial pressure. In patients with chronic lung disease no correlations were shown though a trend between raised pressure and size was observed. We speculate that pulmonary artery compliance is an important factor which determines the degree of dilatation in response to raised pressure. Estimations of pressure cannot be made from measurements of pulmonary artery size without knowledge of the underlying lung disease.     

CT-determined pulmonary artery diameters in predicting pulmonary hypertension

This study was to determine if the diameters of pulmonary arteries measured from computed tomographic (CT) scans could be used 1) as indicators of pulmonary artery hypertension and 2) as a reliable base for calculating mean pulmonary artery pressure. The diameters of the main, left, proximal right, distal right, interlobar, and left descending pulmonary arteries were measured from CT scans in 32 patients with cardiopulmonary disease and in 26 age- and sex-matched control subjects. Diameters were measured using a special computer program that could display a CT density profile of the artery and its adjacent tissues. The upper limit of normal diameter for the main pulmonary artery was found to be 28.6 mm (mean + 2 SD). In the patient group, the diameters were correlated with data from cardiac catheterization. In these patients, a diameter of the main pulmonary artery above 28.6 mm readily predicted the presence of pulmonary hypertension. The calculated cross-sectional areas of the main and interlobar pulmonary arteries (normalized for body surface area [BAS]) were found to give the best estimates of mean pulmonary artery pressure (r = 0.89, P less than 0.001 and r = 0.66, P less than 0.001). Multiple regression analysis gave the useful equation: mean pulmonary artery pressure = -10.92 + 0.07646 X area of main pulmonary artery/BSA + 0.08084 X area of the right interlobar pulmonary artery/BSA (r = 0.93, P less than 0.0001). Because CT allows precise, noninvasive measurement of the diameter of pulmonary arteries, it can be of value in detecting pulmonary hypertension and estimating mean pulmonary artery pressure.     

Computed tomography pulmonary angiogram diagnosis of pulmonary embolism

Over the last decade, contrast-enhanced spiral CT has been established as a non-invasive alternative to catheter angiography and is now regarded as the first-line imaging investigation for the diagnosis of pulmonary embolism (PE). The reported sensitivities for the diagnosis of PE of spiral CT vary from 45 to 100% and the specificities vary from 78 to 100%. Prospective outcome studies have shown a high negative predictive value for a single-detector spiral CT for PE. Patients' outcomes were not adversely affected in these studies when anticoagulation was withheld after a negative CT pulmonary angiogram. The main limitation of single-detector spiral CT has been its limited ability to detect isolated subsegmental PE. However, multidetector spiral CT allows evaluation of pulmonary vessels down to sixth-order branches and significantly increases the rate of detection of PE in segmental and subsegmental levels. The interobserver correlations for diagnosis of subsegmental PE with multidetector spiral CT exceed the reproducibility of selective pulmonary angiography. If appropriate equipment is available (multidetector CT), then CT pulmonary angiogram is safe to be used as the first-line imaging investigation for the diagnosis of PE.     

Unusual pulmonary angiographic findings in suspected pulmonary embolism

Pulmonary arteriography is most commonly performed to diagnose pulmonary embolism. A variety of clinical entities, however, may mimic pulmonary embolism both clinically and scintigraphically. Five patients with abnormal pulmonary arteriograms resulting from diseases other than pulmonary embolism are presented. The clinical, radiographic, and pathologic findings and long-term follow-up in these patients are described. Awareness of the angiographic patterns seen in these unusual cases is important in the differential diagnosis of pulmonary thromboembolism.