类风湿性关节炎手部非增强磁共振血管成像技术研究

目的:研究基于血流敏感散相的平衡稳态自由进动序列的非增强磁共振技术(FSD-bSSFP NC-MRA,FSD-bSSFP)在类风湿性关节炎手部血管成像的应用价值。方法:20例类风湿性关节炎患者采用FSD-bSSFP序列及增强MRA成像(CE-MRA)进行手部血管成像。由2名5年以上MRI诊断经验的放射科医师测量两种成像方式获得手部动脉血管影像的信噪比(SNR)、对比噪声比(CNR),并对图像质量、静脉污染及手部动脉及分支显示情况进行评分。结果:入组病例17例。FSD-bSSFP序列SNR高于CE-MRA(t=3.707,P<0.05),FSD-bSSFP序列与CE-MRA显示手部血管成像CNR无显著性差异(t=0.600,P>0.05);FSD-bSSFP序列动脉图像质量评分高于CE-MRA(Z=-2.271,P<0.05),静脉污染程度低于CE-MRA(Z=-2.722,P<0.05),动脉分支显示评分无统计学差异(Z=-1.027,P>0.05)。结论:FSD-bSSFP技术应用于类风湿性关节炎患者可获得较好的手部血管成像,避免对比剂对肾脏的潜在损害。     

磁共振B-TFE技术肾动脉成像与CE-MRA对照

目的：探讨磁共振三维平衡式快速场梯度回波（B-TFE）技术非对比剂血管成像在肾动脉成像中的临床应用价值。方法：选择17例临床怀疑有肾动脉狭窄的患者行B-TFE和CE-MRA检查;B-TFE组并行采集加速因子取值为1和2。B-TFE组在横轴面图像上测量双侧肾动脉在不同加速因子时的信号噪声比（SNR）、肾动脉与肾周脂肪的对比噪声比（CNR）,CE-MRA组在冠状面图像上分别测量肾动脉的SNR和CNR。所有原始数据经三维MIP重组后由两位放射科医师对肾动脉三维图像质量、肾动脉狭窄程度、肾动脉分支显示及肾静脉伪影等情况进行评分。测量数据和图像评分进行统计学处理。结果：B-TFE组加速因子为1时图像的SNR为118.0±25.1（左）和105.9±29.1（右）,CNR为103.7±33.5（左）和93.1±26.5（右）;B-TFE组加速因子为2时SNR为93.5±23.1（左）和81.5±31.7（右）,CNR为83.1±34.5（左）和69.8±28.8（右）。CE-MRA组肾动脉的SNR为103.8±31.5（左）和93.1±40.8（右）,CNR为88.7±30.1（左）和79.7±38.6（右）。组内和组间SNR及CNR差异均无统计学意义（P〉0.05）。B-TFE图像上肾动脉分支的显示情况好、肾静脉伪影较CE-MRA小,2组间肾动脉三维图像质量、狭窄程度的显示无明显差异。结论：3DB-TFE肾动脉成像技术具有较高的图像信噪比和对比噪声比,可以作为一种新的无创性磁共振血管成像技术应用于肾动脉成像。     

手动脉非增强磁共振血管成像的初步临床应用

目的 初步探讨基于血流敏感散相(FSD)和平衡稳态自由进动(SSFP)的非增强磁共振血管成像(NCE-MRA)技术在显示类风湿性关节炎患者手动脉的临床应用价值。资料与方法 22例类风湿性关节炎患者采用1.5T成像系统进行手动脉NCE-MRA和增强磁共振血管成像(CE-MRA)检查。对手动脉(划分为腕部、掌部和指部3个血管节段)的图像质量进行评分,并对图像信噪比(SNR)、对比度噪声比(CNR)和血管边缘锐利度进行测量。将NCE-MRA和CE-MRA的图像质量和测量值进行统计学比较。结果 22例患者24只手均成功完成NCE-MRA和动态CE-MRA检查。72个血管节段中,NCE-MRA有69个动脉节段的图像质量具有诊断意义,明显高于CE-MRA(96%比83%,P<0.05)。此外,NCE-MRA在手动脉各个部位的图像质量以及SNR、CNR和血管锐利度均优于CE-MRA(P<0.05)。结论 NCE-MRA能清楚地显示手动脉的各个分支,图像质量优于动态CE-MRA,对手动脉病变的诊断具有较好的临床应用潜力。     

序列优化的下肢MR血管成像诊断糖尿病足的价值

目的 探讨序列优化的下肢MRA诊断糖尿病足的价值.方法 前瞻性纳入临床及常规下肢影像检查未见异常,经超声检查排除下肢动脉病变的28名志愿者,分2次行下肢小腿血管MRI增强扫描,并行采集加速因子(PIF)分别为3、4.测量计算腘动脉、胫后动脉、胫前动脉及腓总动脉的信噪比(SNR)及对比噪声比(CNR),并进行图像质量评分.收集临床确诊的糖尿病足患者20例,同一患者均采用方案1(传统的Care-bolus扫描)和方案2(行优化K空间中心填充的延迟时间扫描)行大腿、小腿及足部的增强MRA扫描.对采用不同扫描方案图像的股动脉、腘动脉、胫后动脉、胫前动脉、腓总动脉、足背动脉、足底内侧动脉及足底外侧动脉进行评分,并对大腿、小腿及足部血管进行静脉重叠评分.采用配对t检验比较志愿者在不同PIF时各部位SNR及CNR的差异;采用Wilcoxon检验比较志愿者在不同PIF时小腿血管显示的差异以及患者采用2种方案扫描对各部位血管的评分和静脉重叠评分的差异.结果 志愿者行小腿MRA,PIF=3时,腘动脉、胫后动脉、腓总动脉的SNR分别为267±84、174±51、147±42,CNR分别为232±83、139±51、108±39;PIF=4时,上述部位的SNR分别为239±73、157±53、132±35,CNR分别为206±71、124±50、103±33,上述部位PIF=3时的SNR及CNR均高于PIF=4时,差异有统计学意义(t值为2.31～4.11,P均＜0.05).PIF为3或4时,上述血管显示评分的差异均无统计学意义(P均＞0.05).20例糖尿病足患者采用方案1行下肢MRA,腘动脉、胫后动脉、胫前动脉、腓总动脉、足背动脉、足底内侧动脉、足底外侧动脉的图像质量评分分别为(3.40±0.82)、(2.70±0.80)、(2.50±1.00)、(2.20±0.77)、(2.30±0.92)、(2.15±1.04)、(1.45±0.60)分,小腿及足部的静脉重叠评分分别为(2.20±1.01)、(2.20±1.06)分;采用方案2上述部位的图像质量评分分别为(3.85±0.37)、(3.55±0.69)、(3.30±0.92)、(2.90±0.79)、(3.30±0.92)、(3.25±0.79)、(1.95±1.10)分,小腿及足部的静脉重叠评分分别为(3.70±0.47)、(3.65±0.49)分,差异均有统计学意义(P均＜0.05),方案2优于方案1.结论 适当提高并行采集加速因子、个性化设置K空间中心填充的延迟时间,有助于提高糖尿病足下肢全程血管的成像质量.     

新虚拟单能技术对提高髂股部动脉成像图像质量的价值

目的 评价双能量CT(DECT)新虚拟单能技术(mono-plus)在提高髂股部动脉成像图像质量的价值.方法 收集40例患者行下腹DECT增强扫描.扫描数据经Siemens Syngo.via VB10A工作站处理,分别获得40 keV mono-plus图像、最佳单能量图像和混合能量图像.分别计算并比较3组图像中的髂股部9支动脉的CT值、信噪比(SNR)、对比噪声比(CNR)以及图像质量主观评分.结果 9支动脉40 keV mono-plus图像组的CT值及CNR均明显高于其余2组(P<0.003).7级动脉分支(旋股外侧动脉横支及旋股内侧动脉深支)40 keV mono-plus图像组的SNR值与其余2组间的差异无统计学意义(P>0.05).6级及以上动脉分支40 keV mono-plus图像组的SNR值低于其余2组(P<0.05).40 keV mono-plus图像组主观质量评分显著优于其余2组(P<0.001).结论 与最佳单能量图像及混合能量图像比较,40 keV mono-plus图像可以提高髂股部动脉的显示效果,尤其是在细小分支的显示上,具有明显的优越性.     

双源双能量不同管电压CT肺动脉成像质量的对比研究

目的 定量评价双源双能量CT不同管电压条件下肺动脉及肺动脉栓子显示情况,优选肺栓塞检测的管电压条件.方法 66例临床拟诊肺栓塞的患者中37例经多层螺旋CT肺动脉成像(CTPA)诊断为肺栓塞.对66例患者进行对比增强双源双能量CT肺动脉成像,获得80 kVp(Ⅰ组)、平均加权120 kVp(Ⅱ组)、140kVp(Ⅲ组)3组图像.分别测量3组肺动脉1～4级分支、栓子及背部肌肉的CT值,并计算信噪比(SNR)及对比噪声比(CNR).应用单因素方差分析或多个相关样本Friedman检验,分析3组的CT值、SNR及CNR值是否有统计学差异.利用kappa检验分析2名医师分析不同管电压条件下CTPA图像质量的一致性.结果 Ⅰ组1～4级分支平均CT值为(446±140)、(433±130)、(411±138)、( 392±127) HU.Ⅱ组1～4级分支平均CT值为(303±91)、(290±85)、(276±86)、(263±85) HU.Ⅲ组1～4级分支平均CT值为(244±70)、(230±63)、(216±72)、(205±68) HU.3组肺动脉1～4级分支的CT值差异均有统计学意义(P值均＜0.01),组间比较差异均有统计学意义(P值均＜0.01),Ⅰ组图像的平均CT值均高于Ⅱ组及Ⅲ组.37例CT检查诊断为肺栓塞患者定量分析结果显示,3组栓子CNR值分别为8.3±3.3、8.0±2.9、5.6±2.2.3组间CNR比较有统计学差异(P＜0.01);Ⅰ与Ⅱ组间差异无统计学意义(P＞0.05),Ⅰ与Ⅲ、Ⅱ与Ⅲ组间差异均有统计学意义(P值均＜0.01).3组CTPA图像质量差异无统计学意义(P值均＞0.05),2名医师的评价结果经kappa检验,Ⅰ组图像质量一致性(kappa值=0.789,P＜0.01)高于Ⅱ组(kappa值=0.652,P＜0.01)和Ⅲ组(kappa值=0.509,P＜0.01).结论 80 kVp图像的平均CT值高于平均加权120 kVp及140kVp图像,其图像质量及CNR值与平均加权120 kVp图像相当,可用于临床可疑肺栓塞患者CT肺动脉成像的检查中.     

3.0T高时间分辨率对比增强MRA颅内血管成像

目的:评价3.0T高时间分辨率对比增强磁共振血管成像(TR 3DCE-MRA)在颅内血管成像的技术可行性和临床应用价值。方法:经医院伦理委员会批准,回顾性搜集21例患者,采用3.0T磁共振,首先行常规序列T1WI、T2WI和TOF MRA扫描,然后在确定病变处用TR 3DCE-MRA即快速小角度激发梯度回波序列(3DFLASH)。所有病例在检查后1～3d行高分辨率增强MRA(HR CE-MRA),测量动脉的信噪比和对比噪声比,由2位影像专家对TR CE-MRA和HR CE-MRA图像质量进行评价,分别对图像伪影、静脉污染、脑动脉显示效果进行评分。评分结果采用SPSS 13.0进行统计学分析,差异具有统计学意义(P<0.05)。结果:21例患者中动脉瘤3例,动静脉畸形7例,烟雾病2例,动脉狭窄9例。图像SNR和CNR测量均值分别为237±89和213±94,Wilcoxon test检验结果Z=-3.160,P=0.002<0.05,静脉污染组Z=-4.298,P=0.001<0.01,血管显示组Z=-4.491,P=0.001<0.01,差异有明显统计学意义。结论:TRCE-MRA比HR CE-MRA具有严重伪影少,没有静脉污染,良好的血管对比,能够同时评价动脉血管和静脉血管,将是颅内血管疾病的首选。     

320层容积CT超低剂量扫描在冠状动脉成像中的应用

目的 评价320层CT冠状动脉成像中前瞻性轴面容积扫描不同kV设置对辐射剂量及图像质量的影响,探讨＜1 mSv冠状动脉检查的可行性及应用价值.方法 从拟行冠状动脉成像的患者中连续选取80例,随机分成A、B两组各40例,A组扫描时管电压为100 kV,B组为120 kV.A组经AIDR软件重建后成为A1组.比较A、B两组升主动脉根部平均强化CT值(SI)、噪声(SD)、信噪比(SNR)、对比信噪比(CNR)、有效辐射剂量(E)及图像质量评分.分别比较A、A1和B、A1组间患者SI、SD、SNR、CNR及图像质量评分.结果 A组有效辐射剂量为(0.67±0.18) mSv,B组为(3.08±1.04)mSv(t=- 14.30,P＜0.05),平均减少了78％.A、B两组的图像质量评分分别为(4.57±0.57)和(4.59±0.59)分(t=-1.17,P＞0.05).A、B组SI、SD、SNR、CNR分别为(570.8±131.5)HU、25.1±6.9、24.5±9.1、19.8±6.1和(460.6±14.3)HU、15.1±3.6、31.7±7.7、29.3±6.8.两组SI、SD比较,A组大于B组,差异有统计学意义(t=4.49、8.18,P＜0.05);SNR、CNR A组小于B组,差异有统计学意义(t=-4.24、-6.19,P＜0.05).A1组SI、SD、SNR、CNR、图像质量评分(557.9±24.5)HU、21.1±6.0、27.7±10.0、23.4±7.8、(4.60±0.56)分,与A组相比,SI、图像质量评分差异无统计学意义(t =1.09、-1.90,P＞0.05);SD、SNR、CNR差异有统计学意义(t=-5.97、-4.18、-6.22,P＜0.05).结论 320层CT冠状动脉成像前瞻性轴面容积扫描中,采用100 kV管电压扫描,其辐射剂量可降到1mSv以下,并且图像质量达到诊断要求.     

3D-GRASE序列与2D-FSE序列在磁共振胰胆管造影中的对比研究

目的 探讨单次屏气采集的快速三维梯度自旋回波(3D-GRASE)序列与二维快速自旋回波(2D-FSE)序列在磁共振胰胆管造影(MRCP)中的图像差异。方法 搜集2021年3月至2021年7月在本院行MRCP检查的患者77例,同时扫描2D-MRCP序列和快速3D-MRCP序列,分别计算图像的信噪比(SNR)和对比噪声比(CNR),同时对图像质量进行主观评价。结果 2D-MRCP序列图像的SNR 22.60±18.23,3D-MRCP序列的SNR 24.02±16.73,差异无统计学意义。2D-MRCP序列的CNR 76.46±48.78,低于3D-MRCP序列的胆总管CNR 129.20±66.58,差异有统计学意义(P<0.01)。图像质量、伪影评分无统计学差异。各胰胆管分支的显示中,肝总管、胆总管、胰管的显示有统计学差异(P<0.001)。结论 3D-GRASE序列的图像质量与2D-FSE序列的图像无统计学差异,符合诊断要求,且3D-GRASE序列具有可全方位观察,减少肠道影响的优点。     

能谱CT单能量融合技术优化子宫动脉CTA图像质量研究

目的 探讨能谱CT单能量融合技术对子宫动脉CTA图像质量优化的价值.方法 前瞻性分析行能谱CT盆腔或腹盆腔检查的40例女性的影像资料,采用最佳单能量、70 keV单能量、140 kVp混合能量及最佳单能量与70 keV单能量融合图像显示子宫动脉,比较4组图像对比噪声比(CNR)、信噪比(SNR)、背景噪声及图像主观评分.结果 子宫动脉最佳单能量范围为60～68 keV,均值为(62.38±1.61) keV.最佳单能量组、70 keV组、140kVp混合能量组及融合图像组对子宫动脉的CNR分别为23.16±6.48、17.40 ±4.77、9.51 ±2.73及24.55±5.97;SNR分别为25.98±6.80、20.32 ±5.21、11.41 ±3.00及27.88±6.28;背景噪声分别为25.35±4.74、16.64±3.49、21.30±3.67及18.25 ±3.07.融合图像组CNR与最佳单能量组间差异无统计学意义(P＞0.05),余各组两两比较差异均有统计学意义(P＜0.01);图像主观评分分别为4.03±0.75、3.71 ±0.77、3.06±0.83及4.24±0.67,融合图像组与最佳单能量组主观评分间差异无统计学意义(P＞0.05),余各组两两比较差异均有统计学意义(P＜0.01).融合图像组CNR、SNR及图像主观评分均高于其余3组,背景噪声高于70 keV单能量组,低于最佳单能量及混合能量组.结论 能谱CT单能量融合技术能够优化子宫动脉图像质量,提高子宫动脉远端小分支的显示.     

Noncontrast 3D steady state free precession magnetic resonance angiography of the thoracic central veins using nonselective radiofrequency excitation over a large field of view: initial experience

PURPOSE: To evaluate the feasibility of three-dimensional (3D) steady state free precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation for the assessment of thoracic central veins. MATERIALS AND METHODS: Thirty consecutive patients (17 males, 13 females, age range 22-76) with various cardiac and thoracic vascular diseases underwent free-breathing electrocardiogram-gated noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced (CE) MRA of the thorax at 1.5 T. Two readers evaluated both datasets for findings: venous visibility and sharpness (from 0, not visualized to 3, excellent definition); artifacts; signal-to-noise ratio (SNR); and contrast-to-noise ratio (CNR) in 8 venous segments including superior vena cava (SVC), supra-diaphragmatic inferior vena cava, bilateral brachiocephalic, proximal subclavian, and lower internal jugular veins. Statistical analysis was performed using Wilcoxon test for overall image quality and vessel visibility, t test for SNR and CNR analysis, and kappa coefficient for inter-observer variability. RESULTS: 3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). Reader 1 (2) graded the overall image quality as excellent and good on SSFP MRA in 23 (25) and 7 (5) patients, and on CE-MRA in 22 (23) and 8 (9) patients, respectively. On SSFP MRA, readers 1 and 2 graded 234 (97.5%) and 233 (97.1%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.69), respectively. On conventional CE-MRA, readers 1 and 2 graded 231 (96.3%) and 232 (96.7%) venous segments with diagnostic definition (grades 2 and 3) (kappa = 0.68), respectively. Segmental visibility and sharpness were higher for lower internal jugular veins on CE-MRA for each reader (P < 0.001). No significant difference existed for venous visibility and sharpness scores for other venous segments between the 2 techniques for both readers (P > 0.05). SNR and CNR values were lower for internal jugular veins on SSFP MRA (P < 0.001). No significant difference existed between SNR and CNR values for the other venous segments on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated patent SVC Glenn shunt to main pulmonary artery (n = 3), patent extra cardiac Fontan shunt from inferior vena cava to pulmonary artery confluence (n = 2), and dilatation and thrombosis of SVC (n = 1) and right brachiocephalic vein (n = 1) on both datasets. CONCLUSION: Free breathing navigator-gated noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident evaluation of thoracic central veins.     

Noncontrast 3D steady-state free-precession magnetic resonance angiography of the whole chest using nonselective radiofrequency excitation over a large field of view: comparison with single-phase 3D contrast-enhanced magnetic resonance angiography

OBJECTIVES: To evaluate the feasibility of three-dimensional (3D) steady-state free-precession (SSFP) magnetic resonance angiography (MRA) using nonselective radiofrequency excitation in the assessment of cardiac morphology, thoracic aorta, main pulmonary, and proximal coronary arteries. MATERIAL AND METHODS: Thirty consecutive patients (19 males; 11 females; age range, 20-74) with various cardiac and thoracic vascular diseases underwent free-breathing respiratory navigator-gated electrocardiogram-triggered noncontrast SSFP MRA and conventional high-resolution 3D contrast-enhanced MRA (CE-MRA) of the thorax at 1.5 T. Two readers evaluated both datasets for findings, vascular delineation and sharpness (from 0, not visualized to 3, excellent definition), artifacts, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) in 14 vascular segments including aorta, supra-aortic, pulmonary, and coronary arteries, and in cardiac chambers. Statistical analysis was performed using Wilcoxon test for vessel delineation, and [kappa] coefficient for interobserver variability. RESULTS: 3D SSFP and CE-MRA were successfully performed in all patients. Scan time for SSFP MRA ranged from 5 to 10 minutes (mean +/- standard deviation, 7 +/- 2 minutes). On SSFP MRA, readers 1 and 2 graded 233 (97.1%) and 234 (97.5%) coronary arterial segments and cardiac chambers, and 275 (91.7%) and 278 (92.7%) noncoronary arterial segments with diagnostic definition (grades 2 and 3) (k = 0.86). On conventional CE-MRA, readers 1 and 2 graded 10 (4.2%) and 12 (5%) coronary arterial segments and cardiac chambers, and 272 (90.7%) and 270 (90%) noncoronary arterial segments with diagnostic definition (grades 2 and 3) (k = 0.89). Segmental visibility was higher for aortic root, pulmonary trunk, proximal coronary arteries, and heart chambers (P < 0.001), and lower for supra-aortic arteries (P < 0.001) on SSFP MRA for each reader. SNR and CNR values were higher for aortic root and aorta on SSFP MRA (P < 0.001 for both). No significant difference existed between SNR and CNR values for the other vascular segments and cardiac chambers on SSFP and CE-MRA (P > 0.05 for all). The 2 readers demonstrated vascular stenosis and dilatation/aneurysm in 7 and 35 segments on both datasets, respectively. CONCLUSION: Noncontrast 3D SSFP MRA with nonselective radiofrequency excitation provides high image quality and sufficient SNR and CNR for confident assessment of cardiac and thoracic vascular diseases including congenital heart diseases. Our results suggest that noncontrast SSFP MRA outperforms CE-MRA in visualization of cardiac chambers, proximal coronary arteries, pulmonary trunk, and aortic root.     

FSD-bSSFP非增强MRA下肢动脉病变诊断的初步探讨

目的探讨以血流敏感散相(flow-sensitive dephasing,FSD)为准备脉冲的平衡稳态自由进动序列(bSSFP)在下肢动脉病变中的诊断价值。资料与方法 42例糖尿病患者采用FSD-bSSFP序列非增强磁共振血管造影(NC-MRA)和对比增强磁共振血管造影(CE-MRA)行小腿部动脉扫描,将血管分为胫前动脉、胫后动脉和腓动脉3个节段。以CE-MRA作为参照标准,评价FSD-bSSFP上各血管的狭窄程度(分为0～4级),计算FSD-bSSFP各级血管狭窄程度的敏感性、特异性、阳性预测值、阴性预测值和诊断准确性。运用配对χ2检验分析两种检查方法诊断血管显著性狭窄(≥50%和闭塞)有无统计学差异,并采用Cohen’s kappa检验进行一致性分析。分析FSD-bSSFP在下肢动脉病变的应用价值。结果 42例中41例成功进行了FSD-bSSFP检查,获取243个动脉节段。FSD-bSS-FP对下肢动脉狭窄各级的(0～4级)敏感性分别为97.87%、98.13%、96.86%、94.93%、92.31%;特异性分别为95.10%、93.98%、94.23%、92.31%、84.77%;阳性预测值分别为96...     

3.0T MR单源与多源发射技术对肝脏成像质量影响的对比研究

目的 探讨3.0T MR单源与多源发射技术对肝脏成像质量的影响.方法 回顾性分析107例行3.0 T MR肝脏扫描受试者的图像,检查序列包括频谱选择性衰减反转恢复T2WI( SPAIRT2WI序列、DWI以及平衡式快速场回波(Balanced FFE)序列.每一序列均在单源和多源的激发模式下进行双重采集,采用Student＇st检验比较单多源图像的均匀性与对比度,采用Wilcoxon秩和检验比较单多源图像质量的评分.2名放射科医师独立进行阅片,采用Kappa检验比较读片者之间的诊断一致性.结果 采用单源和多源发射技术测量图像的均匀性分别为418.40±66.75和416.26±50.61,多源发射技术图像均匀性优于单源发射技术,差异有统计学意义(=2.524,P＜0.05).单源和多源发射技术测得的信噪比(SNR)分别为20.36±11.21和22.03±12.16,对比噪声比(CNR)分别为15.22±8.95和18.33±10.01,差异均有统计学意义(t值分别为- 2.630和- 4.238,P值均＜0.05).多源发射技术图像对比度优于单源发射技术图像.SPAIR T2WI序列单源和多源发射技术图像质量评分分别为(1.40±0.42)和(1.81±0.27)分,DWI序列分别为(1.08±0.46)和(1.63±0.36)分,Balanced FFE序列分别为(0.95±0.45)和(1.65±0.37)分,多源发射技术图像质量在上述3个序列中均优于单源发射技术图像(Z值分别为-5.894、-5.801和-6.985,P值均＜0.01).2名评判医师之间的诊断一致性好(Kappa值均＞0.8,P值均＜0.05).结论 相对于单源发射技术来说,多源发射技术能够消除电解质阴影,提供更好的图像均匀性、更高的图像对比度和更佳的图像质量,3.0T多源技术在腹部成像上具有很明显的优势.     

时间分辨随机轨道MR血管成像对周围动脉闭塞性疾病小腿动脉的成像研究

目的 评价3.0 T时间分辨随机轨道(TWIST)MRA提供的小腿动脉血流动力学指标和形态学诊断的价值.方法 40例临床证实或怀疑周围动脉闭塞性疾病(PAOD)的患者接受小腿段TWIST MRA及全下肢对比增强MRA(CE-MRA)检查.由TWIST MRA确定双侧腘动脉开始显示时间,双侧腘动脉开始显影时间差,小腿动脉通过时间和小腿动脉平均达峰时间.分析小腿动脉平均达峰时间与踝肱指数(ABI)的关系.评价小腿各段动脉在TWIST MRA及CE-MRA的图像显示情况,包括血管显示度、静脉重叠情况和动脉狭窄程度.组间比较采用t检验或校正t检验,动脉平均达峰时间与ABI的关系采用Pearson分析.对16例患者,以DSA为金标准,分别评价TWIST MRA、CE-MRA诊断各级动脉狭窄的敏感性和特异性.结果 (1)纳入评价的79侧下肢腘动脉开始显影时间为(30.7±7.6)s,双侧腘动脉开始显影时间差为(2.1±2.5)s,小腿动脉通过时间为(35.6±16.9)s,小腿动脉平均达峰时间为(52.6±17.6)s.(2)24例接受ABI检查的患者共计得到48个ABI指数(均值为0.62±0.23),与小腿动脉平均达峰时间呈正相关(r＝0.627,P＜0.01).(3)851段参与评价的血管中,TWIST MRA显影动脉节段849段,显示度评分为(2.83±0.48)分;CE-MRA显影动脉节段845段,显示度评分为(2.78±0.43)分(P＞0.05).(4)以DSA共显示的194段动脉节段为金标准,TWIST MRA显示正常及轻度狭窄的敏感性为96.7%(118/122)、特异性为100.0% (72/72),显示明显狭窄的敏感性为94.1%(32/34)、特异性为96.2% (154/160),显示闭塞的敏感性为94.7%(36/38)、特异性为98.7% (154/156);CE-MRA显示正常及轻度狭窄的敏感性为95.9%(117/122)、特异性为100% (72/72),显示明显狭窄的敏感性为91.2%(31/34)、特异性为95.6% (153/160),显示闭塞的敏感性为94.7%(36/38)、特异性为98.1%(153/156).结论 TWIST MRA操作简便,无静脉污染,一次检查不仅能准确显示小腿动脉病变,而且能提供反映疾病程度的功能学信息.

Abstract：

Objective To explore the value of time-resolved angiography with interleaved stochastic trajectories (TWIST)in providing hemodynamic indices and morphological imaging of calf arteries in patients with peripheral arterial occlusive disease(PAOD) with 3.0 T MR scanner. Methods Forty patients with confirmed or suspected PAOD underwent TWIST MRA for the calf arteries and conventional contrast-enhanced MRA(CE-MRA) for the whole lower peripheral arteries. TWIST MRA data were used to determine the bolus arriving time of the popliteal artery, the time difference of the bolus arrival in the popliteal artery between the two legs, calf artery transit time, and the mean peak enhancement time of calf arteries. The mean value of peak enhancement time of calf arteries was correlated with ankle-brachial index(ABI). The calf arteries were divided into 13 segments. The visible score of arterial segment was recorded, and the degree of arterial stenosis was graded too. In 16 patients, DSA was used as the gold standard to evaluate the sensitivity and specificity of TWIST MRA and CE-MRA. Results The bolus arriving time of the popliteal artery was (0.7±7.6) s the time difference of the bolus arrival in the popliteal artery between the two legs was (2.1±2.5) s, the calf artery transit time was (35.6±16.9) s, the mean value of peak enhancement time of calf arteries was (52.6±17.6) s. ABI was acquired from 24 patients and 48 legs, which correlated well with the mean value of peak enhancement time in calf arteries (r＝0.627,P＜0.01). The mean visible score was (2.83±0.48) of TWIST MRA images and (2.78±0.43) of CE-MRA images. There was no significant difference between them (P＞0.05). On CE-MRA, there were 38 legs with varying degrees of early venous enhancement; in contrast, there was no venous contamination on TWIST MRA. The sensitivity and specificity of TWIST MRA were 96.7% (118/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 94.1% (32/34) and 96.2% (154/160) in showing severe stenosis, and 94.7% (36/38) and 98.7% (154/156) in showing occlusion. The sensitivity and specificity of CE-MRA were 95.9% (117/122) and 100.0% (72/72) in showing normal artery and mild stenosis, 91.2% (31/34) and 95.6% (153/160) in showing severe stenosis, and 94.7% (36/38) and 98.1% (153/156) in showing occlusion. Conclusion TWIST MRA is a preferable choice for calf arterial occlusive disease, which provided nice morphological images and useful hemodynamic indices with simple operation.     

管电压80kVp时不同浓度对比剂CTPA图像质量的自身对照实验研究

目的 探讨管电压80 kVp条件下保证兔CT肺动脉血管成像(CTPA)图像质量的最低碘对比剂浓度.方法 新西兰大白兔10只,每只间隔3d各行4次CTPA检查,碘对比剂浓度分别为350、300、270、250 mg I/mL.测量肺动脉主干及其同层面空气、左右肺动脉、上肺及下肺段以下肺动脉CT值,计算噪声(N)、对比噪声比(CNR)及信噪比(SNR),均以x-±s表示,采用单因素方差分析进行比较,多重比较采用Dunnettt检验.同时将肺动脉以段级肺动脉为界分为大血管和小血管,采用多个样本比较的Krskal-Wallis H检验,编秩后行LSD-t检验进行多重比较.不同观察者间及同一观察者不同次测量(间隔1月)肺动脉CT值采用配对t检验,血管评分采用配对样本比较的Wilcoxon符号秩检验.结果 不同对比剂浓度的CTPA均可显示6级肺动脉分支.270组肺动脉CT值[主肺动脉(687.17±167.83) HU]与最高的300组无明显差异[主肺动脉(848.68±185.03) HU](t =-161.52,P=0.097).270组CNR(6.3±1.30)及SNR(10.9±2.01)最高(t=-45.99,P=0.008;t=3.73,P=0.088),而N(62.84±6.05)最低(t=-11.09,P=0.016). 270组与其他3组间对于大血管评分无统计学差异(350～250组依次为3.91±0.35,3.90±0.38,3.90±0.42,3.86±0.42,H=6.588,P=0.086).270组对小血管评分低于350组及300组,但达到诊断要求(3.34±0.51).结论 管电压80 kVp时,兔CTPA检查采用270 mg I/mL碘对比剂较合适,可有效降低碘单位注射剂量.     

Initial experience with balanced turbo field echo in depicting carotid artery stenosis: comparison with multiple overlapping thin slab acquisition and 3D contrast-enhanced magnetic resonance angiography

PURPOSE: To compare balanced turbo field echo (bTFE) with multiple overlapping thin slice acquisition (MOTSA) and contrast-enhanced MR angiography (CE-MRA) in depicting carotid artery stenosis. MATERIALS AND METHODS: In this study 86 patients with cerebrovascular disease, who had been referred for a carotid examination, were imaged. All of the patients underwent MOTSA and one of four bTFE sequences followed by CE-MRA. Formatted maximum intensity projections (MIPs) and source images were read in a blinded fashion by a radiologist. Inter- and intrasequence statistical analyses were performed. RESULTS: We first compared image quality (IQ) and fat, background, and venous suppression using four distinct bTFE protocols in 118 carotid arteries, and found that bTFE4 performed the best. We then compared IQ, grades of stenosis, and background and venous suppression among bTFE4, MOTSA, and CE-MRA. bTFE produced significantly better IQ and venous suppression (P < 0.001), and higher SNR and CNR (P < 0.05) when compared to MOTSA. CONCLUSION: The bTFE sequence is robust and provides high-quality images in patients with mild to moderate carotid artery stenosis. Even though there is a tendency to overestimate stenosis with bTFE compared to CE-MRA, the shorter scan time of bTFE coupled with enhanced SNR and CNR measurements validates it as a clinically useful adjunct to MOTSA, if not a replacement.     

Contrast-enhanced peripheral MR angiography using SENSE in multiple stations: feasibility study

PURPOSE: To investigate if the use of parallel imaging is feasible and beneficial for peripheral contrast-enhanced magnetic resonance angiography (CE-MRA). MATERIALS AND METHODS: A total of 19 consecutive patients underwent peripheral CE-MRA using SENSE with two-fold reduction in the upper and lower leg stations. Conventional nonaccelerated imaging using constant level appearance (CLEAR) was used in the aortoiliac station. The findings were compared with those in a similar patient group that underwent peripheral CE-MR angiography using our standard imaging protocol without SENSE. Intraarterial digital subtraction angiography (IA-DSA) was used as the standard of reference. Lower extremity vessels were divided into anatomic segments (aortoiliac, upper legs, lower legs) for review. In each anatomic segment signal- and contrast-to-noise ratios (SNR, CNR), venous contamination, subjective image quality, as well as sensitivity and specificity, were determined for both patient groups. RESULTS: SNR and CNR improved significantly for the aortoiliac and upper leg segments (all P-values < or = 0.001). Small reductions were seen in the frequency of disturbing venous enhancement (P = not significant). There were no significant differences with regards to subjective image quality or diagnostic accuracy (all P > 0.3). Overall sensitivity and specificity in the SENSE group were 81% and 95%, respectively. For the non-SENSE group, these values were 79% and 96%, respectively. CONCLUSION: Preliminary results show that three-station peripheral CE-MRA using a full length peripheral arterial coil in combination with SENSE in the upper and lower leg stations is feasible and useful for further optimization of peripheral MRA. Using SENSE allows for routine, high-quality depiction of the entire peripheral vascular tree including the pedal arch. Higher SENSE factors are needed for further optimization.