Validation of a new contrast material protocol adapted to body surface area for optimized low-dose CT coronary angiography with prospective ECG-triggering

In patients with large total blood volume contrast material (CM) dilution decreases coronary attenuation in CT coronary angiography (CTCA). As increased blood volume is well paralleled by body surface area (BSA) we assessed a BSA-adapted CM protocol to compensate for dilution effects. Low-dose CTCA with prospective ECG-triggering was performed in 80 patients with a BSA-adapted CM bolus ranging 40–105 ml and injection rate ranging 3.5–5.0 ml/s for a BSA of <1.70 to ≥2.5 m². Eighty control patients matched for BSA who had previously undergone routine CTCA with a fixed CM protocol of 80 ml at 5 ml/s served as reference group. The average vessel attenuation from the proximal right (RCA) and the left main coronary artery (LMA) was assessed. Correlation of BSA with vessel attenuation was assessed in both groups. BSA-matching of all patients was successful (BSA-adapted group 1.98 ± 0.15 m², range 1.66–2.39 m² versus reference group 1.98 ± 0.17 m², range 1.59–2.38 m²; P = 0.74). Mean CM bolus was significantly smaller in the BSA-adapted versus the reference group (70.9 ± 14.1 vs. 80.0 ± 0 ml, P < 0.001). There was no correlation in the BSA-adapted group (r = ?0.07, P = 0.53, SEE = 0.15), while coronary attenuation was inversely related to BSA in the reference group (r = ?0.59, P < 0.001, SEE = 0.14). We have successfully validated a BSA-adapted contrast material protocol which results in a comparable coronary contrast enhancement independent of individual BSA. This was achieved despite a significant reduction in the overall contrast material amount.     

Determinants of vessel contrast in BMI-adapted low dose CT coronary angiography with prospective ECG-triggering

We evaluated the determinants of vessel contrast in prospectively ECG-triggered CT coronary angiography (CTCA). Seventy patients underwent low-dose CTCA using Body Mass Index (BMI)-adapted tube parameters and a fixed contrast material bolus. Contrast to noise ratio (CNR) was calculated from contrast (between coronaries and perivascular tissue) and image noise (standard deviation of aortic attenuation). Cardiac output (CO) was calculated from gated ^99mTc-tetrofosmin-SPECT. Mean radiation dose was 2.13 ± 0.69 mSv. Image noise was not affected by BMI (r = 0.1, P = 0.36), while CNR was inversely related to body surface area (BSA) (r = −0.5, P < 0.001) and CO (r = −0.45, P < 0.001). After successfully overcoming the impact of BMI on image noise by adapting tube parameters, CNR mainly depends on coronary vessel contrast. The latter reflects the dilution of the contrast material by blood volume and CO, which are both correlated to BSA. Therefore, BSA adapted contrast administration may help to compensate for this effect.     

个体化注射对比剂软件P3T-PA在CT肺动脉成像中的应用

目的 评估采用个体化对比剂注射软件P3T-PA进行CT肺动脉成像（CTPA）的可行性。方法 将80例临床疑似肺动脉栓塞行CTPA检查患者按随机表分为两组：P3T组（n=40）,采用P3T-PA个性化对比剂注射软件,常规组（n=40）,采用常规对比剂注射方案。测量各级肺动脉（肺动脉主干、左肺动脉、右肺动脉、左下肺动脉基底支、右下肺动脉基底支）CT值及CT值标准差（SD）、左心房CT值（LACTv）,计算肺动脉主干（MPACTv）CT值与LACTv差值（MPACTv－LACTv）及两下肺动脉基底支SNR、CNR,记录对比剂注射流速、用量及扫描延迟时间,并进行统计学分析。结果 两组各级肺动脉CT值、SD值、MPACTv－LACTv及两下肺动脉基底支SNR、CNR差异均无统计学意义（P均>0.05）;P3T组和常规组对比剂注射流速、扫描延迟时间差异无统计学意义;[（4.76±0.50）ml/s vs（4.69±0.40）ml/s,P=0.521;（13.18±1.81）s vs（14.15±4.38）s,P=0.198];P3T组对比剂用量较常规组少[（37.93±3.86）ml vs（49.27±6.76）ml,P<0.001]。结论 采用P3T-PA个体化对比剂注射软件行CTPA检查,操作简便,可精确计算对比剂用量,对比剂用量减少且图像质量良好。     

Low-dose coronary computed tomography angiography using prospective ECG-triggering compared to invasive coronary angiography

To assess the diagnostic accuracy of prospective ECG-triggering 64-slice multidetector computed tomography (MDCT) coronary angiography for evaluation of coronary artery disease (CAD). Forty-two patients (31 males, 11 females, mean age 64 years) underwent cardiac CT and invasive coronary angiography (ICA). Patients with a heart rate of <65 beats/min with stable heart rhythm were included in the study sample. We used a prospective ECG-triggering protocol. Luminal narrowing over 50% was considered to be significant according to a modified 17-segment AHA model, using invasive coronary angiography (ICA) as the standard of reference. The mean radiation dose was 3.5 mSv ± 0.3 (range, 3.3–4.2 mSv), and 542 of 549 segments (98.7%) in the 42 patients were diagnostic. In contrast, 119 of 542 segments (22%) were diagnosed as significant by ICA. The sensitivity, specificity, accuracy, PPV and NPV were 95.0, 96.2, 96, 85.8 and 98.8%, respectively. False positive results were affected by densely calcified plaques, whereas false negatives were caused by motion artifact with poor vessel attenuation at the distal segments or near the bifurcation area of the coronary arteries. Prospective ECG-triggering MDCT is a useful method for evaluating CAD in patients with a lower heart rate with low radiation dose.     

低浓度对比剂在冠状动脉CTA检查中的可行性研究

目的：探讨低浓度碘对比剂（270 mgI/mL）配合低管电压在冠状动脉CTA检查中的可行性。材料与方法：将90例行冠状动脉CTA检查的患者随机分为A组和B组。A组60例应用270 mgI/mL碘对比剂同时使用迭代算法重建,再将A组根据体质量指数（BMI）分为A1组（25例）及A2组（35例）,A1组（BMI〈24 kg/m2）管电压为80 kV,A2组（BMI≥24 kg/m2）管电压为100 kV;B组30例应用370 mgI/mL碘对比剂,120 kV管电压。两组均采用前瞻性心电门控扫描。记录扫描辐射剂量,并对图像质量进行主、客观分析。结果：平均有效辐射剂量（ED）A1组为（2.00±0.56） mSv,A2组为（2.35±0.74） mSv,B组为（3.98±1.78） mSv,A1组与B组间及A2组与B组间均有统计学差异（t值分别为-5.34和-4.95,P〈0.05）。图像质量方面,A1组与B组间及A2组与B组间主观评价优秀率无统计学差异（χ2值分别为1.10和2.04,P值均〉0.05）;客观评价图像噪声（SD）、信噪比（SNR）、对比噪声比（CNR）亦均无统计学差异。结论：应用尽可能低浓度的碘对比剂（270 mgI/mL）配合低管电压在冠状动脉CTA检查中是可行的,超重人群（BMI≥24 kg/m2）亦可应用,同时显著的降低了辐射剂量和碘注射量。     

Novel single-source high-pitch protocol for CT angiography of the aorta: comparison to high-pitch dual-source protocol in the context of TAVI planning

Purpose Computed tomography (CT) is increasingly being used for planning purposes prior to trans-arterial valve implantation (TAVI). High-pitch protocols using a 2nd generation dual-source CT (DSCT) allow for a comprehensive assessment of the aortic valve anulus, its distance to the coronary artery ostia, the aortic bulbus and the iliofemoral arteries with very low radiation exposure and low amount of contrast agent. The aim of this study was to evaluate the image quality of a comparable high-pitch scan mode in a modern single-source CT (SSCT) system. Methods 40 patients with severe symptomatic aortic valve stenosis have been examined for planning purposes prior to TAVI. The first 20 consecutive patients were examined with a 2nd generation DSCT system using a high-pitch scan mode (pitch value 3.4) and 60 ml of contrast agent. The second group of 20 consecutive patients were examined with a 128-slice SSCT system, using a high-pitch scan mode (pitch value of 1.7) and 60 ml of contrast agent. Image quality of the aortic valve, the ascending aorta, the coronary artery ostia, the iliofemoral arteries and overall image quality were graded in a blinded fashion using a 4-point-grading-scale. Furthermore, signal intensity and image noise were derived in the ascending aorta and in the ilio-femoral arteries. Results There was a minor but significant difference in the overall image quality score with lower image quality in SSCT (3.5 ± 0.6) when compared to DSCT (3.85 ± 0.4; p = 0.037). The mean image quality score was significantly higher in patients examined in DSCT when compared to SSCT regarding the evaluability of the coronary ostia (4.0 vs. 3.5; p < 0.01) and the image quality of the ascending aorta (4.0 vs. 3.5; p < 0.01). There was no significant difference in evaluation of the aortic valve and its anulus (3.85 for DSCT and 3.65 for SSCT; p = 0.149) and image quality of the iliofemoral arteries (3.65 for DSCT and 3.85 for SSCT; p = 0.140). Signal intensity and image noise did not differ significantly between both groups. Conclusions This study presents a novel high-pitch protocol for modern SSCT scanners, which allows CT angiography for TAVI planning with a similar radiation dose and contrast agent exposition and only small compromises in image quality compared to a high-pitch protocol on a DSCT scanner.     

大螺距双源CT心脏与头颈血管一站式联合扫描的可行性

目的 评价Flash双源CT前瞻性心电门控螺旋扫描模式（Flash Spiral模式）心脏与头颈血管一站式联合成像的图像质量、辐射剂量。方法 选择246例连续性患者,分为3组,每组82例：A组采用Flash Spiral模式行心脏与头颈血管联合扫描;B组采用Flash Spiral模式心脏成像;C组采用双能量扫描模式行头颈部CTA。分别测量主动脉根部CT值及CNR,测量颈总动脉起始部、颈内动脉起始部、大脑中动脉M1段、椎动脉V4段CT值及图像噪声,评价图像质量、有效辐射剂量。结果 A组与B组冠状动脉平均图像质量评分差异无统计学意义（P>0.05）,A组与C组头颈部血管图像质量评分差异无统计学意义（P>0.05）,A组头颈部ED显著低于C组（t=24.215,P<0.01）。结论 大螺距双源CT Flash Spiral模式心脏与头颈部血管一站式联合扫描图像质量好,成功率高,对比剂用量少,辐射剂量低。     

64层CT冠状动脉成像对比剂注射剂量的优化研究

目的探寻使用64层CT冠状动脉成像最佳的对比剂注射方法。方法将接受64层CT冠状动脉检查的连续30位患者中,分出10位体重低于70kg(A组)和20位体重高于70kg的患者(随机均分成两组B1和B2组),其中A组及B1组注射50ml对比剂(注射速度4.5ml/s),B2组注射70ml对比剂(注射速度5ml/s)。分别比较三组患者的主动脉及冠状动脉主干、主要分支的强化程度。结果A组与B2组患者各段血管的增强程度没有显著性差异,B1组患者部分血管的增强程度明显低于B2组。结论64层CT冠状动脉成像对比剂注射剂量优化方案是可行的,其优越性是明显的。     

心率及心率变异对前瞻性心电门控64层螺旋CT冠状动脉成像图像质量的影响

目的 探讨前瞻性心电门控64层螺旋CT冠状动脉成像中心率及心率变异对图像质量的影响。方法 80名受检者接受前瞻性心电门控扫描,检查前口服美托洛尔将心率控制在65次/分以下。以4分法对各冠状动脉段的最佳图像的质量进行评定。利用Pearson相关分析法分析心率、心率变异对图像质量的影响。结果 80名受检者均顺利完成检查,共纳入分析1039段冠状动脉,其中1003段(96.54%)满足诊断需要。平均有效剂量为(6.07±1.13)mSv。右冠状动脉、左旋支及总体图像质量与心率呈负相关(P＜0.05),左前降支、左主干图像质量与心率无显著相关性。总体及各支冠状动脉图像质量与心率变异无显著相关性。结论 前瞻性心电门控64层螺旋CT冠状动脉成像能够降低辐射剂量,当受检者心率控制在65次/分以下时,心率变异对图像质量无显著影响,但心率仍是影响图像质量的因素之一。     

大螺距双源CT采用bolus-tracking团注法冠状动脉成像的可行性

目的 评价应用缩短呼吸指令时间的团注示踪法(bolus-tracking)行大螺距双源CT冠状动脉成像(CCTA)获得图像的增强效果及有效辐射剂量.方法 收集临床疑诊为冠状动脉性心脏病的184例患者,随机平均分为两组:A组92例,采用大螺距前瞻性心电门控螺旋扫描(Flash Spiral)模式、缩短呼吸指令时间的bolus-t racking法扫描;B组92例,采用测试团注法(test-bolus)扫描.对两组图像的主动脉根部CT值、图像噪声、CNR及有效辐射剂量进行统计学比较.结果 两组图像主动脉根部CT值、图像噪声、CNR间的差异均无统计学意义(P均＞0.05).两组触发时、扫描过程中辐射剂量差异均无统计学意义(P均＞0.05).结论 双源CT大螺距前瞻性心电门控螺旋扫描CCTA中,采用缩短呼吸指令时间的bolus-tracking法可获得与test-bolus法相近的图像增强效果,而对比剂用量进一步减低.     

320排容积CT低管电压结合低浓度对比剂冠状动脉成像与冠状动脉造影的对比研究

目的 探讨320排容积CT冠状动脉CTA低管电压、低浓度对比剂扫描的可行性。方法 前瞻性分析54例临床疑似冠状动脉粥样硬化性心脏病患者的CCTA检查结果,并与经导管冠状动脉造影术(CCA)结果进行对照。CCTA采用100 kV管电压,对比剂采用270 mgI/ml的碘克沙醇。结果 CCTA显示冠状动脉中度以上狭窄(≥50%)及重度狭窄(≥75%)的敏感度、特异度、阳性预测值、阴性预测值、正确指数及符合率分别为89.55%、96.08%、78.95%、98.25%、85.63%、96.84%及92.68%、97.24%、76.00%、99.29%、89.92%、95.16%。CCTA与CCA在显示冠状动脉狭窄程度方面的一致性良(Kappa=0.752,P<0.001)。CCTA诊断冠状动脉中度以上狭窄(≥50%)的ROC曲线下面积为0.930。结论 应用320排容积CT行CCTA低管电压、低浓度对比剂扫描诊断冠状动脉狭窄具有可行性。     

大螺距双源CT前瞻性心电门控冠状动脉成像在高心率患者中的应用

目的评价第二代双源CT大螺距前瞻性心电门控扫描模式(flashspiral)在高心率患者行CT冠状动脉成像(CTCA)中的图像质量及有效射线剂量,探讨最佳采集数据时间。方法接受第二代双源CT冠状动脉成像检查的1321例患者中,选择心率≥70次/min和心率<70次/min者各70例(A组和B组)。两组患者均采用flashspiral模式,A组患者采集图像时间为RR间期20%,B组患者为RR间期55%。比较两组患者CTCA图像质量与有效射线剂量等的差异性。结果 (1)两组患者年龄、性别、BMI、扫描时间比较,差异无统计学意义。(2)图像质量:A组不可诊断冠状动脉节段(评分3分)20段(2.1%),B组不可诊断冠状动脉节段14段(1.5%),两组不可诊断血管节段比较,差异无统计学意义。两组不可诊断节段均常发生在右冠状动脉和左冠脉回旋支。(3)射线剂量:A组平均有效射线剂量为[1.00±0.15(0.7～1.82)]mSv,B组[1.01±0.16(0.65～1.82)]mSv;两组有效射线剂量均在1mSv左右。结论 (1)高心率患者可采用大螺距进行前瞻性心电门控单个心动周期扫描成像。(2)扫描时间窗选择RR间期的...     

基于去脂体质量对比剂注射方案用于能谱CT检查结直肠癌

目的 评估基于去脂体质量(LBW)低剂量对比剂注射方案对于能谱增强 CT显示结直肠癌图像质量的影响,并筛选最佳能级。方法 将150例疑诊结直肠肿物患者随机分为总体质量(TBW)组(A组)、500LBW组(B组)及400LBW组(C组)各50例,分别以500 mgI/kg(TBW)、500 mgI/kg(LBW)、400 mgI/kg(LBW)方案注射对比剂,行能谱CT全腹增强扫描。对A、B组重建70 keV图像,C组重建40~70 keV(间隔10 keV)图像(C_{40~70 keV}亚组),测量动脉期肠系膜上动脉(SMA)、肠系膜下动脉(IMA)和静脉期肝实质CT值,计算信噪比、对比度噪声比和肝脏增强CT值(ΔHU),比较各组图像质量。结果 相比A组,B、C组对比剂剂量分别降低23.00%及37.19%(P均＜0.05)。动脉期A、B组及C_{40~60 keV}亚组SMA和IMA的CT值均＞350 HU。B组SMA及IMA的CT值变异率分别为9.42%和9.32%,C_{60 keV}亚组SMA和IMA的CT值变异率分别为9.82%和10.09%,均低于A组(P均＜0.05)。静脉期中,A、B组及C_{40~60 keV}亚组的ΔHU均＞50 HU。B组和C_{60 keV}亚组ΔHU变异率分为8.60%和8.67%,均低于A组(P＜0.05)。3组动、静脉期结直肠癌标准化碘浓度差异均无统计学意义(P均＞0.05)。C组内C_{60 keV}亚组动、静脉期主观评分均最高,且与A组差异无统计学意义(P均＞0.05);其余各亚组主观评分均低于A组(P均＜0.05)。结论 基于LBW低剂量对比剂注射方案结合能谱CT可利用低对比剂剂量获得高质量图像;60 keV为最佳扫描能级。     

Contrast media volume optimization in high-pitch dual-source CT coronary angiography: feasibility study

To investigate the feasibility of contrast media (CM) volume reduction in dual-source coronary computed tomography angiography high-pitch mode without affecting coronary artery enhancement. Eighty patients were involved in a preliminary experiment with a default injection protocol (60 ml of CM). The age, BMI, test bolus (TB) enhancement peak and the CT values of coronary artery for each patient were recorded and the key factors for determining coronary artery enhancement were investigated. Based on the results of the preliminary experiment, 120 patients were involved in the main experiment with a new injection protocol. For each patient, the CT values and noise of left coronary sinus (LCS), and the distal segment of right coronary artery were measured. In the preliminary experiment, the peak enhancement of TB correlated most strongly with the HU values of coronary artery. Consequently, the new injection protocol was devised to catalog patients into four groups (30, 40, 50 and 60 ml) of CM based on their TB peak enhancement. In the main experiment, the 30 ml CM injection group whose peak attenuation of TB were the highest (30 vs. 40,50,60 ml: 323.0 ± 27.5 vs. 264.2 ± 11.9, 242.1 ± 8.8, 206.2 ± 18.2 HU, p < 0.05), obtained the highest attenuation of LCS (30 vs. 40,50,60 ml: 365.0 ± 41.2 vs. 341.8 ± 40.0, 326.9 ± 34.7, 312.5 ± 38.2 HU p < 0.05). Contrast optimization is feasible in high-pitch DSCT coronary angiography. Certain patients may receive 30 ml of CM without affecting vessel enhancement.     

多层螺旋CT低剂量对比剂肺动脉成像

目的评价低剂量对比剂多层螺旋CT肺动脉造影(CTPA)的成像技术及图像质量。方法应用多层螺旋CT对24名疑似肺栓塞的病人行CTPA检查,对比剂总量为20ml(300mgI/ml)。以单层动态增强扫描所测时间-密度曲线的峰值时间为扫描延迟时间,对比剂注射速率5.5ml/s,数据采集时间2~3s;另随机选择24例常规对比剂剂量(50ml)CT-PA检查影像作为对照组,影像质量按5级行盲法评价。结果试验组5级图像占34%,4级37%,3级29%,未见1级、2级。对照组5级25%,4级34%,3级41%,未见1级、2级。结论20ml的对比剂可使患者肺动脉各级分支显影,并且达到诊断要求。     

Contrast material injection protocol with the flow rate adjusted to the heart rate for dual source CT coronary angiography

To investigate the effect on coronary arterial attenuations of contrast material flow rate adjusted to a patient’s heart rate during dual source CT coronary angiography (DSCT-CCTA). A total of 296 consecutive patients (mean age: 58.7 years) undergoing DSCT-CCTA without previous coronary stent placement, bypass surgery, congenital or valvular heart disease were included. The image acquisition protocol was standardized (120 kV, 380 mAs) and retrospective electrocardiograph (ECG) gating was used. Patients were randomly assigned to one of three groups [flow rate: G1: dosage/16, G2: dosage/(scan time +8), G3: fixed flow rate]. The groups were compared with respect to the attenuations of the ascending aorta (AA) above coronary ostia, the left main coronary artery (LM), the proximal right coronary artery (RCA), the left anterior descending artery (LAD), the left circumflex artery (LCX), and the contrast to noise ratio of the LM (LM_CNR) and the proximal RCA (RCA_CNR). Correlations between heart rate and attenuation of the coronary arteries were evaluated in three groups with linear regression. There was no significant difference in the three groups among the mean attenuations of AA (P = 0.141), LM (P = 0.068), RCA (P = 0.284), LM_CNR (P = 0.598) and RCA_CNR (P = 0.546). The attenuations of the LAD and the LCX in group 1 were slightly higher than those in group 2 and 3 (P < 0.05). In group 1, the attenuations of the AA (P < 0.01), LM (P < 0.01), RCA (P < 0.01), LAD (P = 0.02) and LCX (P < 0.01) decreased, respectively, with an increasing heart rate. A similar finding was detected in group 3 (AA: P < 0.01, LM: P < 0.01, RCA: P < 0.01, LAD: P < 0.01and LCX: P < 0.01). In contrast, the attenuations of the AA (P = 0.55), LM (P = 0.27), RCA (P = 0.77), LAD (P = 0.22) and LCX (P = 0.74) had no significant correlation with heart rate in group 2. In all three groups, LM_CNR (P = 0.77, 0.69 and 0.73 respectively) and RCA_CNR (P = 0.75, 0.39 and 0.61 respectively) had no significant correlation with heart rate. Contrast material flow rate adjusted to heart rate can diminish the influence of heart rate on attenuations of the coronary arteries in DSCT-CCTA.     

Radiation reduction with prospective ECG-triggering acquisition using 64-multidetector computed tomographic angiography

Current 64-multidetector Computed Tomographic scanners (MDCT) utilize retrospective overlapping helical acquisition (RS-OHA) which imparts a higher than desired radiation dose. Although the radiation burden of computed tomographic angiography (CTA) can be efficiently reduced by dose modulation and limiting field of view, a further decrease in radiation without compromising diagnostic image quality would be indeed very desirable. An alternative imaging mode is the axial prospective ECG-triggering acquisition (prospective gating). This study was done to compare the effective radiation dose and the image quality with two techniques to reduce radiation doses with CTA studies utilizing 64-MDCT scanners. The study included 149 consecutive patients (48 females and 101 males) 64-MDCT (mean age = 67 ± 11 years, 72.2% male). Patients underwent CT coronary angiography using one of three algorithms: retrospective triggering with dose modulation; prospective triggering with padding (step and shoot acquisition with additional adjacent phases); and prospective triggering without padding (single phase acquisition only). Based on body habitus, two different voltages were utilized: 100 kVp (<85 kg) or 120 kVp (>85 kg). Radiation doses and image quality (signal to noise ratio) was measured for each patient, and compared between different acquisition protocols. The signal to-noise ratio of the ascending aorta (SNR-AA) was calculated from the mean pixel values of the contrast-filled left ventricular chamber divided by the standard deviation of these pixel values. Use of 100 kVp reduced radiation dose 41.5% using prospective triggering and 39.6% using retrospective imaging as compared to 120 kVp (P < 0.001). Use of prospective imaging reduced radiation exposure by 82.6% as compared to retrospective imaging (P < 0.001). Using both prospective imaging and 100 kVp without padding (single phase data, no other phases obtained), radiation dose was reduced by 90% (P < 0.001). In terms of image quality, the coefficient of variation of ascending aortic contrast enhancement between kVp of 120 and kVp of 100 was 6% (1.05, 95 CI 0.93–1.17), and 7.8% (0.9, 95% CI 0.7–1.2) at the pulmonary artery. The prospective ECG-Triggered acquisition and 100 kVp images were of diagnostic quality, allowing adequate assessment in all patients. CTA using PA and 100 kVp reduced the radiation dose by up to 90% without compromising the image quality.     

Assessment of image quality and radiation dose in prospective ECG-triggered coronary CT angiography compared with retrospective ECG-gated coronary CT angiography

We sought to determine the cut-off point of the average heart rate (HR) and HR differences in obtaining diagnostic image quality using prospective electrocardiographically-triggered (PT) coronary computed tomographic angiography (CCTA) and to compare image quality and radiation dose for CCTA obtained with PT CCTA and retrospective electrocardiographically-gated (RG) CCTA. A total of 178 patients who were referred for CCTA were enrolled in the study. Two independent radiologists evaluated subjective image quality. The non-diagnostic coronary segments were 32 of 1,226 segments (2.6%) for PT CCTA and 12 of 1,346 segments (0.9%) for RG CCTA (P < 0.001). The mean image quality scores for PT CCTA and RG CCTA were 3.82 ± 0.29 and 3.93 ± 0.14, respectively. The mean radiation dose of patients that underwent PT CCTA was 3.83 ± 0.84 mSv and RG CCTA 10.7 ± 2.70 mSv. For patients who underwent PT CCTA, image quality was inversely related to HR (56.5 ± 4.3 bpm; r = 0.38; P < 0.001) and HR differences (2.8 ± 2.7 bpm; r = 0.49; P < 0.001). With the use of receiver operator characteristic analysis, a cut-off HR of 57 bpm (58% sensitivity, 67% specificity) and HR difference of 6 bpm (93% sensitivity, 46% specificity) were the best threshold for the prediction of diagnostic image quality. In patients with a regular, low HR, PT CCTA offers diagnostic image quality and substantially reduces effective radiation compared with the use of RG CCTA with dose modulation.     

采用低管电压技术和低剂量对比剂行256层螺旋CT头颈部动脉成像的可行性

目的探讨采用低管电压技术和低剂量对比剂进行256层螺旋CT头颈部动脉检查的可行性。方法将60例接受头颈部CTA检查的患者随机分为A、B、C组,管电压和对比剂用量分别为120kV、70ml,120kV、50ml,100kV、50ml,对比分析图像质量、血管增强情况、静脉伪影及辐射剂量。结果①除右侧锁骨下动脉外,各主要动脉节段影像评分三组间差异无统计学意义;②B组血管CT值最低,C组最高,3组间差异均有统计学意义(P均<0.05);③A组静脉伪影较B组、C组明显(P均<0.05),B组与C组间差异无统计学意义(P>0.05)。A、B组辐射剂量高于C组(P均<0.05),A组与B组间差异无统计学意义(P均>0.05)。结论采用低管电压、低剂量对比剂进行头颈部256层螺旋CTA可获得较好的图像质量,能够满足临床诊断需要。