低管电压联合ASiR-V算法“一站式”心脑血管CTA扫描模式的应用价值

目的：探讨低管电压联合ASiR-V算法“一站式”心脑血管CTA扫描模式在动脉粥样硬化导致的心脑血管疾病评估中的临床应用价值。方法：回顾性分析需要进行心脑血管疾病筛查扫描的120例患者。依据扫描方式不同,分为3组,每组40人。A组为低剂量一站式”心脑血管CTA扫描模式组（80 kV,管电流智能调控,前置40%ASIR-V,后置50%ASiR-V）,B组为常规剂量冠状动脉CTA扫描组（100 kV,550 mA）,C组为常规剂量头颈动脉CTA扫描组（100 kV, 500 mA）。对比3组扫描模式的辐射剂量和对比剂用量,同时将3组图像进行主观评价和客观评价。结果：低管电压联合ASiR-V算法“一站式”心脑血管CTA扫描模式有效辐射剂量为（1.36±0.66）mSv,B组的辐射剂量为（2.31±0.75）mSv,C组的辐射剂量为（1.12±0.04）mSv,A组辐射剂量与B组+C组辐射剂量之和差异有统计学意义（P<0.05）,A组与B组的LAD近端、LCX近端、RCA近端的CT值差异均无统计学意义（P>0.05）,A组与B组的SD、CNR值差异无统计学意义（P>0.05）,...     

基于数字模拟技术胸部CT扫描不同组织的噪声*

背景：在CT图像中,图像噪声水平与影像质量密切相关,它直接影响和限制着CT对低对比度物质的分辨力。 目的：通过图像空间添加噪声软件模拟低剂量CT图像,分析模拟噪声指数与不同组织噪声的相关性及胸部不同组织的噪声变化特点。 方法：利用图像空间添加噪声软件对20名自愿者在常规参数下扫描获得的原始图像进行噪声添加,模拟10,30,50,80,100,120,150,180 及240 mA共9组胸部低剂量图像,记录每幅图像噪声指数,测量主动脉弓层面、心脏层面、肺底3个层面的胸壁软组织、主动脉、脊柱、肺组织及空气中CT值的标准差。 结果与结论：图像添加法计算的模拟噪声指数与主动脉弓及其他组织噪声实测噪声差异有显著性意义(P < 0.05),呈线性相关。胸部低剂量扫描时,当管电流在10~50 mA时噪声显著增加,80~240 mA时模拟噪声值随着管电流增高降低幅度逐渐减低。胸部各组织120 mA组与180 mA组图像噪声差异无显著性意义(P > 0.05)。提示图像空间添加噪声软件的噪声指数反映了图像不同组织的整体噪声水平。胸部低剂量CT检查时采用管电流120~180 mA时能够保证各组织噪声无明显变化的同时又可以降低辐射剂量。     

Assessment of Image Quality for Selective Intracoronary Contrast-Injected CT Angiography in a Hybrid Angio-CT System: A Feasibility Study in Swine

PurposeTo compare image quality in selective intracoronary contrast-injected computed tomography angiography (Selective-CTA) with that in conventional intravenous contrast-injected CTA (IV-CTA).Materials and MethodsSix pigs (35 to 40 kg) underwent both IV-CTA using an intravenous injection (60 mL) and Selective-CTA using an intracoronary injection (20 mL) through a guide-wire during/after percutaneous coronary intervention. Images of the common coronary artery were acquired. Scans were performed using a combined machine comprising an invasive coronary angiography suite and a 320-channel multi-slice CT scanner. Quantitative image quality parameters of CT attenuation, image noise, signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), mean lumen diameter (MLD), and mean lumen area (MLA) were measured and compared. Qualitative analysis was performed using intraclass correlation coefficient (ICC), which was calculated for analysis of interobserver agreement.ResultsQuantitative image quality, determined by assessing the uniformity of CT attenuation (399.06 vs. 330.21, p<0.001), image noise (24.93 vs. 18.43, p<0.001), SNR (16.43 vs. 18.52, p=0.005), and CNR (11.56 vs. 13.46, p=0.002), differed significantly between IV-CTA and Selective-CTA. MLD and MLA showed no significant difference overall (2.38 vs. 2.44, p=0.068, 4.72 vs. 4.95, p=0.078). The density of contrast agent was significantly lower for selective-CTA (13.13 mg/mL) than for IV-CTA (400 mg/mL). Agreement between observers was acceptable (ICC=0.79±0.08).ConclusionOur feasibility study in swine showed that compared to IV-CTA, Selective-CTA provides better image quality and requires less iodine contrast medium.     

腹部螺旋CT血管成像图像质量与辐射剂量的关系

目的探讨在行腹部CT血管成像（CTA）检查时图像质量与辐射剂量的关系,以求获得最高的质量剂量比。方法收集2008年3月至2012年4月在本院行腹部CTA的患者270例,随机分成管电压、管电流及螺距组,每组90例。管电压组分140、120、100kV3级,每级30例;管电流组分400、300、200mA3级,每级30例;螺距组分0．5、1、1．53级,每级30例。采用64排螺旋CT扫描从膈顶2cm到腹主动脉髂总动脉分叉处,在腹主动脉近端设置触发兴趣区。当造影剂CT值达到120HU时,触发扫描并记录辐射剂量。把动脉期容积数据发送到Vitrea工作站进行最大密度投影（MIP）、容积再现（vRT）处理,通过血管的显影、饱满度、整体性、对比度、伪影等的综合得分来评估图像质量,进而对比各组的图像质量与辐射剂量。结果管电压组中随着管电压从140kV下降到100kV,腹部CTA的图像质量与辐射剂量均下降,辐射剂量的下降程度更大（P〈0．05）。120kV与140kV的图像质量均在优良以上,差异没有统计学意义（P=0．19）,100、120kV管电压下的图像质量比140kV时分别下降41．3％（P〈0．05）、8．7％。患者采用的辐射剂量从140kV下降到100kV逐渐下降,3级管电压组之间辐射剂量的差异有统计学意义（均P〈0．05）,120kV的图像质量剂量比最高。管电流组中,随着管电流从400mA下降到200mA,腹部CTA的图像质量与辐射剂量同时下降,但辐射剂量的下降程度更大（P〈0．05）,300mA与400mA的图像质量均在优良以上,差异没有统计学意义（P=O．21）,200、300mA管电流下的图像质量比400mA时下降了40．4％（P〈0．05）、10．6％。患者采用的辐射剂量从400mA到200mA逐渐下降,3级管电流组之间辐射剂量的差异有统计学意义（均P〈0．05）,300mA的质量剂量比最高。螺距组中,随着螺距从0．5上升到1．5,腹部CTA的图像质量和辐射剂量同时下降,辐射剂量下降程度更大（P〈0．05）。螺距1与0．5的图像质量均在优良以上,差异没有统计学意义（P=0．20）,螺距1．5的图像质量比螺距0．5、1时下降了50．O％（P〈0．05）、10．9％。在患者采用辐射剂量上,螺距0．5、1、1．53级螺距组之间辐射剂量的差异有统计学意义（均P〈0．05）,1的质量剂量比最高。结论适当的降低管电压、管电流及增加螺距,图像质量虽有所下降,但能满足诊断要求,而辐射剂量下降的幅度更大,这有利于x线的全民防护。     

常规头部CT螺旋扫描与轴扫描模式的影像质量对照

目的通过头部CT螺旋扫描和轴扫描两种不同扫描模式的影像质量对照,探讨常规头部CT采用螺旋扫描模式取代轴扫描模式的可行性。方法 40例患者,其中男性24例,女性16例;年龄18～74岁,平均年龄46岁。分别接受头部CT螺旋扫描和轴扫描两种不同模式扫描,轴扫描参数:140kV、170mA用于颅底部;120kV、150mA用于颅脑部,每周2s。螺旋扫描参数:120kV,150mA,每周0.6s。扫描剂量直接取自设备剂量指示值(CTDI和DLP)。影像质量分别由2位专家采用双盲法,对头部CT的颅底、脑灰-白质层面及全部影像逐层进行CT值测量评估。结果常规头部CT螺旋扫描模式较轴扫描模式可有效去除颅底部伪影,并能减少扫描时间和扫描剂量(轴扫描模式与螺旋扫描模式对比,CTDI 55.43 mGy/37.80 mGy;DLP 662.10 mGy.cm/498.28 mGy.cm;扫描时间12.0 s/7.2 s)(P<0.001)。结论常规头部CT螺旋扫描模式的影像质量完全可与轴扫描模式相媲美,并可取代轴扫描模式。同时常规头部CT螺旋扫描模式还具有可减少扫描时间和辐射剂量,并可进行影像的二维和三维后处理,有利于提高微小病灶正确诊断率的优越性。     

低剂量与常规剂量CT扫描在头颅检查中的对比研究

目的对比分析低剂量与常规剂量头颅CT扫描的辐射剂量比以及低剂量扫描对图像质量的影响。方法对120例头颅患者作头颅CT扫描,分为220mA、100mA、80mA3种剂量扫描,评价3种剂量扫描的图像质量;分别记录3种剂量扫描CT剂量容积(CTDIvol)和剂量长度乘积DLP(mGy.cm)。结果与常规剂量220mA扫描比较,100mA扫描对头颅图像的观察诊断没有影响;80mA扫描时图像颗粒增粗,组织结构分辨率下降,影响观察诊断以220mA为标准,低剂量组80mA和100mA的CTDIvoI、DLP分别是常规剂量组的36.7%、36.7%和45.9%、45.9%。结论100mA低剂量CT扫描对头颅细微显示没有明显影响,不影响观察诊断,完全可应用于头颅扫描方法。     

Automatic exposure control in multichannel CT with tube current modulation to achieve a constant level of image noise: experimental assessment on pediatric phantoms

Automatic exposure control (AEC) systems have been developed by computed tomography (CT) manufacturers to improve the consistency of image quality among patients and to control the absorbed dose. Since a multichannel helical CT scan may easily increase individual radiation doses, this technical improvement is of special interest in children who are particularly sensitive to ionizing radiation, but little information is currently available regarding the precise performance of these systems on small patients. Our objective was to assess an AEC system on pediatric dose phantoms by studying the impact of phantom transmission and acquisition parameters on tube current modulation, on the resulting absorbed dose and on image quality. We used a four-channel CT scan working with a patient-size and z-axis-based AEC system designed to achieve a constant noise within the reconstructed images by automatically adjusting the tube current during acquisition. The study was performed with six cylindrical poly(methylmethacrylate) (PMMA) phantoms of variable diameters (10-32 cm) and one 5 years of age equivalent pediatric anthropomorphic phantom. After a single scan projection radiograph (SPR), helical acquisitions were performed and images were reconstructed with a standard convolution kernel. Tube current modulation was studied with variable SPR settings (tube angle, mA, kVp) and helical parameters (6-20 HU noise indices, 80-140 kVp tube potential, 0.8-4 s. tube rotation time, 5-20 mm x-ray beam thickness, 0.75-1.5 pitch, 1.25-10 mm image thickness, variable acquisition, and reconstruction fields of view). CT dose indices (CTDIvol) were measured, and the image quality criterion used was the standard deviation of the CT number measured in reconstructed images of PMMA material. Observed tube current levels were compared to the expected values from Brooks and Di Chiro's [R.A. Brooks and G.D. Chiro, Med. Phys. 3, 237-240 (1976)] model and calculated values (product of a reference value multiplied by a dose ratio measured with thermoluminescent dosimeters). Our study demonstrates that this AEC system accurately modulates the tube current according to phantom size and transmission to achieve a stable image noise. The system accurately controls the tube current when changing tube rotation time, tube potential, or image thickness, with minimal variations of the resulting noise. Nevertheless, CT users should be aware of possible changes of tube current and resulting dose and quality according to several parameters: the tube angle and tube potential used for SPR, the x-ray beam thickness (tube current decreases and image noise increases when doubling x-ray beam thickness), the pitch value (a pitch decrease leads to a higher dose but also to a higher noise), and the acquisition field of view (FOV) (tube current is lower when using the small acquisition FOV compared to the large one, but the use of small acquisition FOV at 120 kVp leads to a peculiar increase of tube current and CTDIvol).     

智能最佳管电压技术在128层螺旋CT全腹部检查中应用探讨

目的探讨128层螺旋CT智能最佳管电压(CAREkV)技术对腹部扫描辐射剂量及其图像质量的影响。方法选择2013年10月至12月90例行CT常规全腹部检查患者,其中男性50例,女性40例;年龄46~75岁,平均年龄61.6岁。随机分为3组:A组30例,扫描管电压为120kV,360mA;B组30例,扫描管电压为120kV和电流CAREDose 4D技术;C组30例,扫描管电压为CAREkV技术和电流CAREDose4D技术;3组其他扫描参数和图像重建参数均相同。由2名高年资放射科医师对3组图像质量进行评价。测量肝门层面肝实质的CT值及图像噪声(SD),比较各组信噪比(SNR)、对比噪声比(CNR)、平均容积CT剂量指数(CTDIvol)、剂量长度乘积(DLP)、有效剂量(ED)。结果图像主观评价A组得分3.73,B组3.50,C组3.60,3组差异无统计学意义(P0.05)。CNR,A组0.49,B组0.38,C组0.50;SNR,A组3.53,B组2.81,C组3.31;A组与C组CNR和SNR比较,差异无统计学意义(P0.05),B组与A组、C组比较,差异均有统计学意义(P0.05)。A、B、C 3组CTDIvol、DLP比较,差异有统计学意义(P0.05)。A、B、C 3组ED分别为(13.25±1.3)mSv、(7.57±1.9)mSv、(6.36±1.6)mSv,两两之间差异均有统计学意义(P0.05)。结论 CARE kV技术能够根据患者个体差异自动选择kV及mA,在保证图像质量的同时,可以有效地减低辐射剂量。     

图像域迭代重建算法对腹部CT平扫图像质量和辐射剂量的影响

目的:探讨图像域迭代重建算法对腹部CT平扫图像质量及辐射剂量的影响。 方法:以辽阳市中心医院2017年1月~2018年4月行腹部CT平扫的150例患者为研究对象,依据就诊先后顺序随机将其分为观察组与对照组,各75例。均行自动毫安控制技术扫描,管电压均为130 kV。观察组预设图像质量参考毫安秒150 mAs,行图像域迭代重建算法重建;对照组预设图像质量参考毫安秒250 mAs,行滤波反投影重组。通过CT值、图像噪声SD、图像信噪比、对比噪声比评价两组图像客观质量,并行图像质量主观评价,记录两组CT剂量容积指数。 结果:观察组肝脏、脾脏的图像噪声SD均显著低于对照组,图像信噪比均显著高于对照组,差异有统计学意义（P<0.05）;CT值、对比噪声比、主观整体质量评分两组比较差异均无统计学意义（P>0.05）;观察组CT剂量容积指数为（10.02±2.85） mGy,显著低于对照组的（15.68±4.36） mGy,差异有统计学意义（P<0.05）。 结论:图像域迭代重建算法不仅能保证腹部CT平扫图像质量,而且能有效减少辐射剂量。     

等中心扫描降低多层螺旋CT冠状动脉血管成像辐射剂量的随机对照研究

目的 探讨等中心扫描对降低冠状动脉多层螺旋CT血管成像(MSCTA)辐射剂量的价值。方法 采用前瞻性随机对照研究方法。纳入广东省中医院珠海医院2016年11月—2018年4月144例行冠状动脉MSCTA检查患者,将患者按随机区组法分为A、B、C、D 4组,每组36例。A组采用常规扫描定位,电流为智能毫安;B、C、D组采用等中心位置扫描,电流分别为智能毫安、智能毫安的90%、智能毫安的80%。4组扫描管电压均为120 kV。比较4组患者冠状动脉MSCTA图像的客观图像质量噪声、信噪比(SNR),主观质量评分比及辐射剂量(ED),对直径＞1.5 mm的血管节段采用冠状动脉15分段法评分,用以评价主观图像质量。客观噪声方面,4组重建图像中的主支气管选择,感兴趣区(面积约15.0 mm²),测量其标准差值作为噪声值,SNR为其CT值/标准差。结果 MSCTA图像分析显示,以D、A、C、B组为序,噪声依次降低(分别为15.09±2.97、2.68±2.47、2.57±2.29和2.45±4.36),SNR依次升高(分别为63.74±19.78、78.64±14.66、78.66±14.84和79.66±22.90);D组与A、B、C组两两比较,噪声高而SNR低,差异均有统计学意义(P值均＜0.05);A、B、C组间噪声及SNR两两比较,差异均无统计学意义(P值均＞0.05)。4组冠状动脉图像质量主观评分优良率98.9%(1 939/1 960),4组间比较差异均无统计学意义(P值均＞0.05);A、B、C、D辐射剂量依次降低,分别为(3.39±1.39)mSv、(2.89±1.21)mSv、(2.56±1.05)mSv,(2.14±0.87)mSv,其中A组明显高于C、D组,B组高于D组,差异均有统计学意义(P值均＜0.05)。结论 在不降低冠状动脉成像质量的情况下,等中心扫描能降低冠状动脉MSCTA的辐射剂量。     

Survey of practitioners’ competency for diagnosis of acute diseases manifest on chest X-ray

Background

Model-based iterative reconstruction (MBIR) is a promising reconstruction method which could improve CT image quality with low radiation dose. The purpose of this study was to demonstrate the advantage of using MBIR for noise reduction and image quality improvement in low dose chest CT for children with necrotizing pneumonia, over the adaptive statistical iterative reconstruction (ASIR) and conventional filtered back-projection (FBP) technique.

Methods

Twenty-six children with necrotizing pneumonia (aged 2 months to 11 years) who underwent standard of care low dose CT scans were included. Thinner-slice (0.625 mm) images were retrospectively reconstructed using MBIR, ASIR and conventional FBP techniques. Image noise and signal-to-noise ratio (SNR) for these thin-slice images were measured and statistically analyzed using ANOVA. Two radiologists independently analyzed the image quality for detecting necrotic lesions, and results were compared using a Friedman’s test.

Results

Radiation dose for the overall patient population was 0.59 mSv. There was a significant improvement in the high-density and low-contrast resolution of the MBIR reconstruction resulting in more detection and better identification of necrotic lesions (38 lesions in 0.625 mm MBIR images vs. 29 lesions in 0.625 mm FBP images). The subjective display scores (mean ± standard deviation) for the detection of necrotic lesions were 5.0 ± 0.0, 2.8 ± 0.4 and 2.5 ± 0.5 with MBIR, ASIR and FBP reconstruction, respectively, and the respective objective image noise was 13.9 ± 4.0HU, 24.9 ± 6.6HU and 33.8 ± 8.7HU. The image noise decreased by 58.9 and 26.3% in MBIR images as compared to FBP and ASIR images. Additionally, the SNR of MBIR images was significantly higher than FBP images and ASIR images.

Conclusions

The quality of chest CT images obtained by MBIR in children with necrotizing pneumonia was significantly improved by the MBIR technique as compared to the ASIR and FBP reconstruction, to provide a more confident and accurate diagnosis for necrotizing pneumonia.

     

Predicting outcome based on Swenerton score in patients with metastatic breast cancer undergoing high-dose chemotherapy and autologous hematopoietic stem cell transplantation: implications for patient selection.

The aim of this study was to study the effectiveness of the Swenerton score in assessing extent of disease as an independent prognostic and predictive factor in patients with metastatic breast cancer (MBC) who receive high-dose chemotherapy (HDCT) with autologous hematopoietic stem cell transplant (AHSCT). Two-hundred thirty-two patients with MBC underwent HDCT. Extent of disease was assessed quantitatively using the Swenerton score. A retrospective analysis was performed using Cox proportional hazards regression and logistic regression models. One hundred three (44%) patients had a complete response (CR) after HDCT. Bone marrow as source of hematopoietic stem cells, hormone-receptor-negative status, and visceral involvement correlated with both worse overall survival (OS) and progression-free survival (PFS). Short disease-free interval, multiple sites of metastatic disease, and less than 50% reduction in the Swenerton Score during induction chemotherapy correlated with worse OS. Patients in CR at the time of HDCT had better PFS than patients in partial response, stable disease, or progressive disease. Fifty-six patients who underwent conversion to CR after HDCT had a similar median OS (not reached v 74 months; P =.51) and PFS duration (22 v 44 months; P =.15) as patients who received HDCT after a CR to standard-dose chemotherapy (SDCT). Conversion to CR was predicted by a >/=50% reduction in the Swenerton score during SDCT (odds ratio [OR] 3.32, P <.01) and soft-tissue disease (OR 4.08, P <.01). The presence of multiple metastatic sites predicted decreased probability of conversion to CR (OR 0.34, P <.01). The Swenerton score provides a thorough estimate of disease extent, and reduction of Swenerton score by SDCT is potentially useful for selecting the optimal candidates for HDCT trials who may achieve long-term disease control.     

低剂量迭代重建技术在放疗定位图像中的应用

目的:探讨新型低剂量迭代重建技术应用于放疗定位图像的可行性。方法:基于体模的实验数据,对CT辐射剂量进行分析。对CT值、低对比度分辨率、噪声、均匀性以及几何畸变各项质量评价参数进行定量的分析。对仿真体模进行迭代重建技术扫描重建,并在放射治疗计划系统中对仿真体模进行模拟剂量计算,分析感兴趣体积的绝对剂量和平面内剂量的Gamma通过率。结果:低剂量迭代重建技术能够在保证图像质量的同时减少约60%的CT扫描辐射剂量。当管电压保持不变时,低剂量迭代重建技术对TPS剂量计算的准确性的影响可以忽略不计,感兴趣体积剂量最大差异0.6%,面剂量的Gamma通过率优于99.82%。低剂量迭代重建技术对图像低对比度分辨率有一定影响,需要进一步结合临床影像进行分析。结论:低剂量迭代重建技术可以应用于放疗定位图像中,但是需要注意图像特性和某些图像质量的改变,建议与PET-CT、超声、核磁等检查手段结合综合考虑确定靶区范围。 【关键词】低剂量迭代重建;放射治疗;定位图像     

Effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies

The purpose of this study was to investigate the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using multi-detector row CT (MDCT). Following the standard CT perfusion study protocol, continuous (cine) scans (1 s/rotation x 60 s) consisting of four 5 mm thick contiguous slices were performed using an MDCT scanner with a tube voltage of 80 kVp and a tube current of 200 mA. We generated the simulated images with tube currents of 50 mA, 100 mA and 150 mA by adding the corresponding noise to the raw scan data of the original image acquired above using a noise simulation tool. From the original and simulated images, we generated the functional images of cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) in seven patients with cerebrovascular disease, and compared the correlation coefficients (CCs) between the perfusion parameter values obtained from the original and simulated images. The coefficients of variation (CVs) in the white matter were also compared. The CC values deteriorated with decreasing tube current. There was a significant difference between 50 mA and 100 mA for all perfusion parameters. The CV values increased with decreasing tube current. There were significant differences between 50 mA and 100 mA and between 100 mA and 150 mA for CBF. For CBV and MTT, there was also a significant difference between 150 mA and 200 mA. This study will be useful for understanding the effect of x-ray tube current on the accuracy of cerebral perfusion parameters obtained by CT perfusion studies using MDCT, and for selecting the tube current.     

Ultra-low dose CT attenuation correction for PET/CT

A challenge for positron emission tomography/computed tomography (PET/CT) quantitation is patient respiratory motion, which can cause an underestimation of lesion activity uptake and an overestimation of lesion volume. Several respiratory motion correction methods benefit from longer duration CT scans that are phase matched with PET scans. However, even with the currently available, lowest dose CT techniques, extended duration cine CT scans impart a substantially high radiation dose. This study evaluates methods designed to reduce CT radiation dose in PET/CT scanning. We investigated selected combinations of dose reduced acquisition and noise suppression methods that take advantage of the reduced requirement of CT for PET attenuation correction (AC). These include reducing CT tube current, optimizing CT tube voltage, adding filtration, CT sinogram smoothing and clipping. We explored the impact of these methods on PET quantitation via simulations on different digital phantoms. CT tube current can be reduced much lower for AC than that in low dose CT protocols. Spectra that are higher energy and narrower are generally more dose efficient with respect to PET image quality. Sinogram smoothing could be used to compensate for the increased noise and artifacts at radiation dose reduced CT images, which allows for a further reduction of CT dose with no penalty for PET image quantitation. When CT is not used for diagnostic and anatomical localization purposes, we showed that ultra-low dose CT for PET/CT is feasible. The significant dose reduction strategies proposed here could enable respiratory motion compensation methods that require extended duration CT scans and reduce radiation exposure in general for all PET/CT imaging.     

双低扫描方案结合迭代重建CT血管成像在婴幼儿先天性心脏病诊断的应用

【摘要】目的:探讨双源炫速CT-flash低剂量扫描技术及低对比剂注射方案结合迭代重建CT血管成像在婴幼儿先天性心脏病诊断中的价值。方法:收集拟诊断为先天性心脏病行心脏血管扫描的患者86例,随机分为实验组（44例）与对照组（42例）,分别采用双低扫描方案与常规扫描方案,记录两组患者的对比剂用量,容积CT剂量指数和剂量长度乘积,计算有效辐射剂量（ED）;由两位经验丰富的放射医师独立诊断并采用4分法对图像质量进行评估,对结果一致性评价采用Kappa检验;测量两组图像的信噪比和对比度噪声比（CNR）;以数字减影血管造影或手术结果作为金标准,比较两种扫描方法的诊断价值。结果:实验组患儿的ED为（0.30±0.16） mSv,对照组患儿ED为（0.97±0.34） mSv,差异有统计学意义（P<0.01）;对比剂注射剂量分别为（10.01±1.87）和（16.04±3.17） mL,差异有统计学意义（P<0.05）;实验组图像质量评分（3.40±0.57）分,优于对照组（2.90±0.89）分,两组图像均符合诊断要求,差异有统计学意义（P<0.05）;两组图像CNR差异有统计学意义;实验组与对照组的诊断敏感度分别为97.4％和97.9％,特异度分别为98.7％和97.7％,诊断准确率分别为98.3%和97.8%,差异无统计学意义。结论:双低扫描方案结合迭代重建技术可大大降低婴幼儿患者的CT辐射剂量与对比剂注射剂量,图像质量优于常规扫描方案,且诊断准确率高,适合在临床扫描中推广运用。     

小剂量造影剂联合不同电压对CT肺动脉造影图像质量的影响

目的:观察小剂量造影剂联合不同电压对CT肺动脉造影（CTPA）图像质量的影响。方法:选取2016年1月至2018年5月在滦州市人民医院就诊高度怀疑为肺动脉栓塞患者90例,拟行CTPA明确诊断,以随机数字表法分为A、B、C组,造影剂、电压不同。A组电压为120 kV,造影剂剂量为50 mL;B组电压为100 kV,造影剂剂量为50 mL;C组电压为80 kV,造影剂剂量为30 mL。3组均基于自动管电流调制技术设置管电流,其他参数一致。对比各组图像质量及辐射剂量。结果:B、C组肺动脉主干、左右肺动脉、肺段动脉CT值均明显高于A组,信噪比与对比噪声比均明显低于A组（P<0.05）。3组患者的图像质量主观评分均能达到3~6分,且评分未见统计学差异（P>0.05）。B、C组扫描后实际容积CT剂量指数、扫描长度与剂量长度之积及有效剂量明显低于A组（P<0.05）。结论:与传统扫描条件比较,小剂量造影剂联合低管电压（80 kV）扫描条件下行CTPA检查可在明显降低造影剂剂量的同时保证图像质量,有效减少辐射剂量。     

小剂量低辐射手动触发技术在CT肺动脉血管成像中的应用价值

目的:探讨小剂量低辐射手动触发技术在CT肺动脉血管成像（CTPA）中的应用价值。方法:90例疑似肺栓塞（PE）患者随机分为常规组（n=45）和小剂量组（n=45），常规组行常规模式（120 kV，50 mL对比剂）的CTPA扫描，小剂量组行低管电压小剂量对比剂（80 kV或100 kV，30 mL对比剂）的CTPA扫描。比较两组图像质量及辐射剂量。结果:CT值和SNR在两组肺动脉主干和右肺S10段肺动脉中比较均无统计学意义（P>0.05），而CNR在两组肺动脉主干和右肺S10段肺动脉中比较均无统计学意义（P>0.05），在右肺S1段肺动脉中，常规组的CNR则显著高于对照组，差异具有统计学意义（P<0.05）。两位观察者对图像质量分析有着极好的一致性（Kappa=0.865, P<0.001）。常规组CTDIvol、DLP、ED值分别为（8.89±1.96） mGy、（296.5±78.4） mGy[?cm、（4.45±1.76） mSv，均明显高于小剂量组的（3.12±0.68） mGy、（99.6±17.3） mGy[?cm、（1.09±0.27） mSv（P<0.05），小剂量组的ED值相比常规组降低约76%。结论:小剂量低辐射手动触发技术应用于CTPA中是可行的，在获取满足诊断需求图像质量的同时，能够有效减少辐射剂量及对比剂用量，提高检查安全性。     

Multislice CT of the head and body routine scans: Are scanning protocols adjusted for paediatric patients?

Purpose:

To investigate whether the multislice CT scanning protocols of head, chest and abdomen are adjusted according to patient’s age in paediatric patients.

Materials and Methods:

Multislice CT examination records of paediatric patients undergoing head, chest and abdomen scans from three public hospitals during a one-year period were retrospectively reviewed. Patients were categorised into the following age groups: under 4 years, 5–8 years, 9–12 years and 13–16 years, while the tube current was classified into the following ranges: < 49 mA, 50–99 mA, 100–149 mA, 150–199 mA, > 200 mA and unknown.

Results:

A total of 4998 patient records, comprising a combination of head, chest and abdomen CT scans, were assessed, with head CT scans representing nearly half of the total scans. Age-based adjusted CT protocols were observed in most of the scans with higher tube current setting being used with increasing age. However, a high tube current (150–199 mA) was still used in younger patients (0–8 years) undergoing head CT scans. In one hospital, CT protocols remained constant across all age groups, indicating potential overexposure to the patients.

Conclusion:

This analysis shows that paediatric CT scans are adjusted according to the patient’s age in most of the routine CT examinations. This indicates increased awareness regarding radiation risks associated with CT. However, high tube current settings are still used in younger patient groups, thus, optimisation of paediatric CT protocols and implementation of current guidelines, such as age-and weight-based scanning, should be recommended in daily practice.     

体质量指数指导Z轴自动管电流调制技术在胸部CT扫描中应用价值

目的评价体质量指数（BMI）指导下降低Z轴自动管电流调制技术最大毫安值在胸部CT扫描中的图像质量和辐射剂量,降低辐射剂量应用价值。方法连续选取100例BMI正常同时胸部CT定位像扫描显示无明显异常的受检者,随机分2组,每组50例。低剂量组,男性30例,女性20例,年龄18～75岁,中位年龄为39.74岁;对照组,男性30例,女性20例,年龄18～75岁,中位年龄为41.8岁。2组均使用Z轴自动管电流调制技术,Z轴自动管电流设置范围低剂量组30～200mA,对照组30～350mA。记录CT扫描后机显示容积CT剂量指数（CTDIvol）和剂量长度乘积（DLP）,计算有效剂量（ED）。取每例患者肺尖部、主动弓部、肺底部3幅图像,共计300幅。由2名副主任医师采用5分制双盲法评判,测量相应部位的噪声。所有数据记录录入Excel,分析采用SPSS13.0。结果低剂量组和对照组的图像质量主观评判均符合临床诊断要求。低剂量组的图像噪声肺尖部为12.27±2.64,主动弓部为10.83±2.03,肺底部为13.67±2.98。对照组图像噪声肺尖部10.96±2.42,主动脉弓部为9.71±2.72,肺底部为11.17±2.06。低剂量组噪声值高于对照组,两组比较,差异有统计学意义（P〈0.05）。低剂量组平均CTDIvol、ED分别为（5.89±1.63）mGy、（3.26±0.92）mSv,对照组平均CTDIvol、ED分别为（8.07±2.13）mGy、（4.47±1.20）mSv。结论BMI指导下降低Z轴自动管电流调制技术最大毫安值在胸部CT扫描中既能保证图像满足诊断要求,又大幅降低了受检者辐射剂量。