128层螺旋CT低管电压技术在下肢血管疾病中的应用价值

发布时间：2018-01-24 01:26

本文关键词： 体层摄影术 X线计算机低管电压下肢动脉疾病　出处：《山东大学》2014年硕士论文　论文类型：学位论文

【摘要】：研究背景近年来,随着人口的老龄化和糖尿病人的增加,下肢动脉硬化性疾病的发生率明显提高。以前,数字减影血管造影(digital subtraction angiography, DSA)一直是评价下肢血管病变的金标准,但因其有创、费用高、易发生并发症等缺点,已较少用于下肢血管的首选检查。超声亦可显示下肢血管,但受操作者经验影响大,其空间分辨力低,不能为外科医生提供血管全貌,从而不易进行准确的术前评价。磁共振血管造影(Magnetic Resonance Imaging,MRA)具有无创、无辐射的优点,但因其会高估血管的狭窄,小血管空间分辨率比CTA明显降低,并且MRI有很多禁忌证,操作时间也长,对血管钙化显示欠佳。多层螺旋CT(multi slice spiral computed tomography,MSCT)推广应用以来,由于它的强大优点,如无创、扫描速度快及图像后处理功能强大等,CT血管成像(CTangiography,CTA)已变成下肢动脉疾病的重要检查手段。但是CTA的缺点是扫描范围大,从而使受检查者接受的辐射剂量增加,造成的潜在危害很大；另一方面,由于对比剂对人体具有肾毒性等不良反应,降低对比剂用量日益受到重视。本文采用128层螺旋CT低管电压联合低对比剂技术对下肢动脉疾病患者进行CTA检查,探讨该技术在降低辐射剂量和对比剂用量方面的临床应用价值。目的主要探讨128层螺旋CT低管电压技术在下肢动脉疾病应用的可行性及临床价值；同时关注低对比剂的应用价值。方法选择2012年12月至2013年10月利用128层螺旋CT行下肢动脉CTA检查的患者60例,采用低管电压技术(80kV)进行扫描,其中12例患者于CTA检查后一周内行数字减影血管造影(DSA)检查。将图像传至工作站进行容积再现(Volume Rendering,VR)、最大密度投影(maximum intensity projection,MIP)和多平面重组(multiplanar reconstruction,MPR)等图像后处理,对图像质量进行分析。测量每次扫描的股动脉、胭动脉、胫后动脉、股直肌的CT值和股直肌的标准差(standard deviation, SD)三次,取平均值,以SD作为背景噪声,计算出信噪比(Signal to Noise Ratio, SNR)及对比信噪比(contrast-to-noise ratios,CNR)。记录CT容积剂量指数(CT dose index volume,CTDIvoI)、剂量长度乘积(dose length product, DLP),得出有效辐射剂量(effective dose, ED)。为进行对照,又连续统计出2012年1月至2012年11月接受常规剂量(120kV,150mAs)CTA检查的60例患者的SNR, CNR、CTDIvoI、DLP、ED)。由2名具有多年心血管影像诊断经验的放射医师以5分制对图像质量进行主观评价,包括下肢动脉横断面及重组图像的清晰度、血管显示程度及整体图像质量等。采用SPSS19.0进行统计学分析,包括独立样本的t检验、单因素方差检验(one-way ANOVA检验)。两名医师之间的主观评分的一致性进行Kappa检验。以DSA为标准,计算低剂量组12例行DSA检查患者CTA的敏感度、特异度、准确度、阳性预测值、阴性预测值。结果此次低kV扫描共检出双下肢动脉硬化并管腔狭窄、部分闭塞者(ASO)39例,动静脉瘘者4例,下肢动脉血栓型闭塞性脉管炎者(TAO)15例,下肢动脉畸形1例,双侧胭窝陷迫综合征1例。12例患者CTA与DSA比较,低管电压(80kV)CTA诊断下肢动脉狭窄与闭塞的敏感度为99.3%,特异度为95.2%,准确率为98.5%,阳性预测值为97.9%,阴性预测值为98.2%。80kV组和120kV组下肢动脉平均CT值分别为：533.42±63.00HU、376.28±46.95HU,前者较后者较增加明显。80kV组的CTDIvoI、DLP、ED分别为4.88±0.00mGy.602.85±42.00mGy.cm,9.05±0.63mSv,120kV组的CTDIvoI、DLP.ED分别为：10.07±0.00mGy、1282.80±61.81mGy.cm、19.20±0.88mSv,前者较后者辐射剂量下降了近50%。A医师80kV组及120kV组的平均分为4.32±0.54、4.37±0.58,组间差别无统计学意义；B医师80kV组及120kV组的平均评分分别为4.33±0.54、4.42±0.53,组间差别无统计学意义。两名医师对图像的主观评分一致性好(Kappa=0.921,P0.01).结论采用低管电压技术行下肢动脉CTA检查,受检者的辐射剂量和对比剂用量明显降低,且图像质量满足诊断要求,对下肢动脉疾病的诊断和复查具有较大的临床应用价值。
[Abstract]:Background: in recent years, with the increase of population aging and diabetes, the incidence of lower extremity arterial disease was significantly improved. Previously, digital subtraction angiography (digital subtraction angiography, DSA) has been the gold standard for assessment of lower extremity vascular disease, but because there is a high cost disadvantage, prone to complications etc. that is less used. The preferred examination of lower extremity vascular ultrasound can show lower extremity vessels, but by the effect of operator experience, the spatial resolution is low, cannot provide the picture for vascular surgeons, which is not easy to evaluate the accuracy of preoperative magnetic resonance angiography. (Magnetic Resonance, Imaging, MRA) has the advantages of non-invasive, no radiation but, because of the overestimation of vascular stenosis, vascular spatial resolution is much lower than CTA and MRI, there are a lot of contraindications, the operation time is long, on vascular calcification of multi-slice spiral C showed poorly. T (multi slice spiral computed tomography, MSCT) application has strong because of its advantages, such as non-invasive, fast scanning speed and powerful image postprocessing, CT angiography (CTangiography, CTA) has become an important examination method for lower extremity arterial diseases. But the disadvantage is that the CTA scan range, radiation to check the received dose by increasing the potential harm caused by the great; on the other hand, due to the contrast agent has adverse effects on human renal toxicity, reduce the amount of contrast agent is paid more and more attention. In this paper, using 128 slice spiral CT low tube voltage and low contrast agent in patients with lower extremity arterial disease were examined by CTA, to investigate the technology in reducing radiation dose and contrast agent dosage in clinical application value.
Objective to explore the 128 layer spiral CT low voltage technology in application feasibility and clinical value of lower limb arterial disease; at the same time, pay close attention to the application value of low contrast. Methods from December 2012 to October 2013 by CTA in 60 patients with 128 slice spiral CT for lower extremity arteries in patients with low tube voltage (80kV) scan, 12 of them patients in the CTA examination within one week after the digital subtraction angiography (DSA) examination. The images were transmitted to the workstation for volume rendering (Volume Rendering, VR), maximum intensity projection (maximum intensity, projection, MIP) and multiplanar reconstruction (multiplanar reconstruction MPR) image postprocessing, analysis of image quality. Shares measurement of artery, each scan popliteal artery, posterior tibial artery, the rectus femoris CT value and the standard deviation of the rectus femoris (standard deviation, SD) three times, were mean to SD as background noise meter To calculate the signal-to-noise ratio (Signal to Noise Ratio, SNR) and contrast to noise ratio (contrast-to-noise ratios, CNR). Record the volume CT dose index (CT dose index volume, CTDIvoI), dose length product (dose length, product, DLP), the effective radiation dose (effective, dose, ED). For the control. Statistics from January 2012 to November 2012 and received routine dose (120kV, 150mAs) CTA examination of 60 cases of patients with SNR, CNR, CTDIvoI, DLP, ED). By 2 radiologists with years of cardiovascular imaging experience to 5 points on the image quality of subjective evaluation, including cross section and reorganization of lower extremity artery image definition, vascular display level and overall image quality. The SPSS19.0 for statistical analysis, including independent samples t test, one-way ANOVA test (one-way ANOVA test). Kappa consistency between subjective scores of two physicians. Test. Based on the standard of DSA, calculation of low dose group DSA was performed in 12 cases of patients with CTA sensitivity, specificity, accuracy, positive predictive value, negative predictive value. Results the low kV scan were detected in the lower limb arteriosclerosis and stenosis, partial occlusion (ASO) in 39 cases, 4 cases of arteriovenous fistula that type of arterial thrombosis obliterans patients (TAO) in 15 cases, lower extremity artery malformation in 1 cases, bilateral popliteal entrapment syndrome of 1 cases of.12 patients with CTA and DSA, low tube voltage (80kV) CTA in the diagnosis of lower extremity arterial stenosis and occlusion of the sensitivity was 99.3%, specificity was 95.2%. The accuracy rate was 98.5%, the positive predictive value was 97.9%, negative predictive value of 98.2%.80kV group and 120kV group of lower extremity artery average CT = 533.42 + 63.00HU, 376.28 + 46.95HU, the former than the latter is increased significantly in group.80kV, CTDIvoI, DLP, ED were 4.88 + 0.00mGy.602.85 + 42.00mGy.cm, 9.05 + 0.63mSv, group 120kV the CTDIvoI, DLP.ED were 10.07 + 0.00mGy, 1282.80 + 61.81mGy.cm, 19.20 + 0.88mSv, the radiation dose decreased an average of nearly 50%.A physicians in 80kV group and 120kV group was 4.32 + 0.54,4.37 + 0.58, the differences were not statistically significant; Dr. B 80kV group and 120kV group. The average score was 4.33. 0.54,4.42 + 0.53, difference between the groups was not statistically significant. Two physicians subjective score of image consistency (Kappa=0.921, P0.01). Conclusion the low voltage technology for lower extremity arterial CTA examination, radiation dose and dosage of contrast subjects decreased significantly, and the image quality meets the requirement of diagnosis, diagnosis and review lower extremity arterial disease has great clinical application value.

【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R543;R816.2

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