3D BH-GRASE序列与3D RT-TSE序列进行MRCP的应用价值分析

目的 探讨对比分析三维屏气梯度-自旋回波（3D BH-GRASE序列）与三维呼吸触发快速自旋回波（3D RTTSE）序列进行磁共振胰胆管成像（MRCP）的应用价值。方法 选取在我院因怀疑胰胆管病变而行腹部MRI检查的患者,均接受3D RT-TSE序列与3D BH-GRASE序列MRCP扫描。比较两种序列扫描时间、图像质量评分及显示病变情况。结果 3D BH-GRASE序列的扫描时间为（16.4±1.7）s明显短于3D RT-TSE序列的（258.6±31.2）s,差异有统计学意义（P<0.05）;3D BH-GRASE序列扫描图像胆囊、肝内胆管、胆囊管、胰管、胆总管等主要分支评分均明显高于3D RTTSE序列,差异有统计学意义（P<0.05）;两种扫描序列方法对各区域病变检出率差异无统计学意义（P>0.05）。结论MRCP检查应用3D BH-GRASE序列扫描能够保证图像质量及显示病变,同时缩短扫描时间。     

对比剂剂量优化在心脏MRI延迟强化扫描中的临床应用

目的 在心脏MRI延迟强化中,通过分别注射不同剂量(10 mL、20 mL与30 mL)钆喷酸匍胺,观察它们图像质量,优化对比剂剂量.方法 选取志愿者30例(随机分成3组)行心脏MRI延迟强化检查,通过测量不同剂量图像的信噪比(SNR)、对比信噪比(CNR),包括心肌信噪比(SNRmyo)、血池信噪比(SNRbp)和心肌与血池信噪比(CNRbp/myo)等参数评价图像差别.结果 统计学结果显示对比剂剂量20 mL与30 mL图像质量无差异(P＞0.05),而10 mL与30 mL图像质量有差异(P＜0.000 1),后者图像质量优于前者;SNRmyDo、SNRbp和CNRbp/myo 20 mL与30 mL之间没有统计学差异.结论 在心脏MRI延迟扫描中,使用对比剂剂量20 mL时,既可以保证图像质量、满足临床诊断要求,又可以更安全可靠.     

99Tcm-MIBI SPECT/18F-FDG PET与心脏MRI评价特发性扩张型心肌病心肌损伤的对比研究

目的 比较99Tcm-MIBI SPECT/18F-FDG PET心肌灌注/代谢显像与心脏MRI延迟增强成像2种影像学方法评价特发性扩张型心肌病(IDCM)心肌损伤的特点.方法 对42例明确诊断为IDCM的连续患者[其中男29例,女13例,年龄(53±12)岁],行99Tcm-MIBI SPECT、18F-FDG心肌灌注/代谢显像和心脏MRI延迟成像,间隔时间为3～7d.利用17节段模型分别为各节段心肌灌注和代谢图像的放射性摄取评分,共分为4个等级:0=摄取正常,1=摄取轻度降低,2=摄取中度降低,3=摄取严重降低.根据心肌灌注/代谢匹配情况分为正常、不匹配、轻中度匹配、完全匹配4组;根据心脏MRI延迟成像结果分为无延迟强化、壁间强化、透壁强化3组,采用x2检验比较不同强化组间的灌注/代谢异常率差异和不同灌注/代谢匹配组间的延迟强化发生率.结果 全部42例患者中,18例心脏MRI延迟成像出现延迟强化,其中94.4％ (17/18)患者心肌灌注/代谢异常;而另外24例心脏MRI延迟成像无延迟强化患者中,仅有33.3％ (8/24)患者心肌灌注/代谢异常(x2=15.944,P＜0.001).心肌节段分析中,无延迟强化、壁间强化、透壁强化3组相应的心肌灌注/代谢情况有差异,灌注/代谢正常率分别为86.2％ (526/610)、71.0％ (44/62)和28.6％ (12/42)(x2=14.276,P＜0.001).灌注/代谢不匹配组中75.9％ (63/83)的心肌节段无延迟强化,而灌注/代谢完全匹配组透壁强化的发生率(44.4％,12/27)明显高于其他3组[正常组2.1％(12/582)、不匹配组18.1％(15/83)、轻中度匹配组13.6％(3/22),x2=112.530,P＜0.001].结论 心脏MRI延迟成像检测轻度纤维化更敏感,而心肌灌注/代谢显像能够检测更多受损但存活的心肌.结合2种影像学方法评价IDCM患者心肌损伤可以提供更加全面的信息.     

腹部低场强MRI中的半扫描技术

目的:探讨磁共振成像的半扫描技术在低场腹部扫描中的应用价值.材料和方法:使用0.2T开放式永磁型MRI仪对20例患者进行腹部SE-T1WI序列扫描,均采用Half-scan技术,NSA分别为4、6、8,并同时完成非Half-scan技术、NSA 4扫描作为对照.对上述4种图像的同一层面进行对比分析,包括SNR、运动伪影、图像质量及扫描时间.结果:与对照相比,Half-scan技术4次采集的扫描时间明显缩短,6次采集的运动伪影抑制效果最佳(t=6.28,P＜0.001)且扫描时间有所缩短,8次采集的伪影抑制效果较佳(t=3.25,P＜0.01)但扫描时间有所增加.SNR间无明显统计学差异.结论:低场MRI半扫描技术配合恰当的采集次数可显著抑制运动伪影,保证良好的SNR,缩短检查时间,从而获得优质的MR图像.     

正常肝脏和肝硬化门静脉高压患者CT增强扫描参数研究

目的 :探讨正常肝脏和肝硬化门静脉高压患者增强扫描参数对图像质量的影响。方法 :收集正常志愿者(60例)和肝硬化门静脉高压患者(90例),依据对比剂剂量、扫描时间,将正常志愿者分为常规组(A组)和大剂量组(B组),将肝硬化门静脉高压患者分为常规剂量常规扫描组(C组)、大剂量常规扫描组(D组)、大剂量延时扫描组(E组),每组各30例。获得双期图像后,测量动脉期肝动脉CT值,门静脉期门静脉、肝实质、肝静脉CT值及门静脉肝实质CT值差值,并对双期图像质量进行双盲目测评分。结果:A组与B组肝动脉、门静脉、肝静脉CT值及门静脉与肝实质CT值差值比较差异均有统计学意义(P0.05),肝实质CT值2组间比较差异无统计学意义;A组、B组图像质量评分差异无统计学意义。C组与D组比较,肝动脉、门静脉、肝实质、肝静脉CT值、门静脉与肝实质CT值差值差异有统计学意义(P0.05)。E组与D组比较,肝动脉、门静脉强化程度差异无统计学意义;肝静脉CT值、肝实质CT值上升,门静脉与肝实质CT值差值减小,差异有统计学意义(P0.05);C组、D组、E组图像质量评分差异有统计学意义(P0.05)。结论:当对比剂注射速率为3 m L/s时,正常人对比剂剂量为1.5 m L/kg体质量,动脉期扫描起始时间28 s,门静脉期扫描起始时间60 s,可获得较满意图像;肝硬化门静脉高压患者对比剂剂量为2.0 m L/kg体质量,动脉期扫描起始时间33 s,门静脉期扫描起始时间70 s,可获得较满意图像。     

心脏磁共振单次屏气三维容积电影成像在心脏功能评价中的应用

【摘要】目的：探讨单次屏气三维（3D）平衡式稳态自由进动（bSSFP）心脏电影成像评估心脏功能方面的可行性。方法：对20例入选的心脏疾病患者进行常规心脏各切面的2D bSSFP序列和单次屏气心脏全容积3D bSSFP序列的电影成像。采集的MRI图像由2名经验丰富的放射科医师采用双盲法进行分析。采用四分法对图像的总体质量进行等级评分（1分为最差,4分为最优）,然后利用两种序列的图像,分别测量左心室舒张末容积（EDV）、收缩末容积（ESV）、每搏输出量（SV）、射血分数（EF）、心排量（CO）和心指数（CI）。依据数据的正态性分布情况,采用配对t检验或秩和检验比较两种序列的图像质量评分和心功能各项参数值,并进行Pearson相关分析或Spearman相关分析。结果：20例患者均成功完成两种序列的电影成像。3D序列扫描时间［(23.0±2.7)s］明显短于2D序列总成像时间［(488.8±27.0)s］,3D和2D序列的图像质量评分分别为（2.90±0.31）和（3.55±0.60）分,差异具有统计学意义（Z=3.357,P=0.001）。剔除3例2D或3D图像质量较差有可能影响诊断的患者,对余下的17例患者进行心功能评价,2D和3D序列的心功能参数比较结果显示,EDV（t=2.519,P=0.023）和ESV（t=2.804,P=0.013）在两者间差异具有统计学意义;而SV（Z=1.254,P=0.210）、EF（t=1.728,P=0.103）、CO（Z=1.250,P=0.211）和CI（Z=0.995,P=0.320）在两者间差异无统计学意义。相关性分析显示2D和3D序列的EDV、ESV、SV、EF、CO和CI结果均高度相关（相关系数r分别为0.992、0.995、0.981、 0.999、0.985和0.965,P均<0.01）。结论：相对于常规2D bSSFP序列,单次屏气3D bSSFP序列电影成像的图像质量虽略低,但在保证左心室功能评估的准确性的同时,大大节约CMR成像的时间成本。     

孤立肺结节多层螺旋CT容积灌注成像的临床价值

目的 探讨多层螺旋CT容积灌注成像在孤立肺结节诊断中的价值.资料与方法 85例孤立肺结节(直径≤4cm,57例恶性,15活动性炎性,13例良性)患者,在增强(从肘静脉注入非离子型对比剂)前、后采用ToshibaAquilionMarconi16层螺旋CT(采用4×i模式,i代表扫描层厚)及GELightspeed64层螺旋CT(采用8×i或16×i模式,i代表扫描层厚)进行同层动态扫描.11～41s,每1s扫描1次;90s扫描1次.16层螺旋CT:病灶直径3～4cm时,扫描层厚8mm;2～3cm时,扫描层厚6mm;1.5～2cm时,扫描层厚4mm;1～1.5cm时,扫描层厚3mm;＜1cm时,扫描层厚2mm.64层螺旋CT:病灶直径3～4cm时,扫描层厚5mm;＜3cm时,扫描层厚2.5mm.记录孤立肺结节增强前后各时相的CT值.分别计算肺结节有效层面的强化值、灌注值、结节-主动脉强化值比、平均通过时间,有效层面参数的平均值作为肺结节的容积灌注成像定量参数.结果 恶性(36.52±11.07)HU与炎性(37.69±7.10)HU结节强化值明显高于良性(7.02±5.85)HU结节(P＜0.001;P＜0.001).恶性与炎性结节强化值无显著差异(P=0.686＞0.05).炎性结节与大动脉增强峰值比(17.49±3.78)%明显高于良性(2.78±2.23)%与恶性(14.73±4.28)%结节(P＜0.001;P=0.019＜0.05).恶性结节与大动脉增强峰值比明显高于良性结节(P＜0.001).炎性(47.83±31.29)mlmin-1100g-1结节灌注值明显高于良性(3.03±3.01)mlmin-1100g-1与恶性(31.15±9.66)mlmin-1100g-1结节(P＜0.001;P＜0.001).恶性结节灌注值明显高于良性结节(P＜0.001).炎性(33.00±8.87)HU与恶性(40.45±7.03)HU结节平扫的CT值明显低于良性(50.51±10.87)HU结节(P＜0.001;P＜0.001).炎性低于恶性结节平扫的CT值(P=0.002＜0.01).结论 多层螺旋CT容积灌注成像有助于结节鉴别诊断.     

16层CT心电图调制电流对有心率波动的心脏CT扫描曝光剂量及图像质量影响

目的 利用心脏体模评估16层螺旋CT心脏扫描时,不同的心率波动对心电图调制技术降低曝光剂最能力的影响,以及不同的心电图调制电流参数对曝光剂量和图像质量的影响.方法 将跳动的心脏模具设定为60次/min(bpm)基础心率,并根据不同的心率波动情况分为6组,关闭心电图调制电流对心脏模具进行心脏扫描.扫描同时记录各扫描序列的曝光剂量,在采集到的图像中进行冠状面重建后选取中心层而测量球囊图像信噪比的标准差(SD)值,然后根据二维及三维图像质量情况进行分级分析;随后开启心电图调制电流,分4组采用不同的心电图调制电流参数进行心脏CT扫描,分别重复上述扫描并记录曝光剂量,对采集到的图像进行相同测量和记录.将5次扫描所测得的数据进行统计分析,对图像信噪比分别进行方差分析,F检验及两样本比较的秩和检验.结果 采用宽期相(69%～99%)高mA输出,高心率波动(≥7.5 bpm)和低心率波动图像的图像信噪比SD值(分别为27.78与26.30),差异无统计学意义(P＞0.05),二维图像及三维图像质量经检验证明其差异无统计学意义(P＞0.05);仪在85%期相选择高mA输出,高心率波动(≥7.5 bpm)和低心率波动图像的图像信噪比SD值(分别为26.78与29.90)差异1竽在统计学意义(P＜0.01).在心率波动情况下,心电图调制开启时(0.47～0.79 mSv)比关闭时曝光剂昔(0.85 mSv)有明显减低,曝光剂量最多可减少44.7%,并且不同设置的心电图调制电流在曝光剂量的比较中差异也有统计学意义(P＜0.01).模具实验的散点图显示,心电图调制电流开启时,心率波动≤12.5 bpm时,曝光剂量随心率波动改变不明显(变化为0.1～1.1 mSy),但是当心率波动＞12.5 bpm时,曝光剂量将明显增加(达到0.6～1.7 mSv).结论 16层螺旋CT心脏扫描时,即使心率存在一定的波动,开启心电图调制电流技术仍能够有效降低曝光剂量,同时对图像质量无明显影响.     

16层螺旋CT冠状动脉成像图像质量相关影响因素分析及最佳扫描条件选择(心脏体模模拟实验)

目的 采用新型心脏动态体模,对16层螺旋CT冠状动脉成像图像质量相关影响因素进行分析,并探讨在不同心率下的扫描速度和重组算法选择.材料与方法 采用GE公司研制的新型心脏动态体模,心率设置为40～95次/min(间隔5次/min)共12组.采用GE LightSpeed 16 层螺旋CT,以心脏冠状动脉扫描模式对不同心率下的心脏体模进行扫描,X线球管转速(即扫描速度)设置为0.5 s/r和0.6 s/r.所有的扫描数据在R-R间期90%时相分别以单扇区(Snapshot segment)、双扇区(Burst-2)和四扇区重组(Burst-4)3种心脏重组算法进行重组.所有重组数据传至AW4.1工作站行后处理成像.后处理方法采用容积再现(VR)、多平面重组(MPR).分别对不同重组图像进行评分.统计学处理采用析因分析和多元线性回归分析.结果 (1)总模型具有统计学意义(F=11.15,P＜0.0001),不同心率(F=11.99,P＜0.0001)、不同转速(F=5.76,P=0.00196)、不同重组算法(F=9.21,P=0.0003)对图像质量有显著的影响,三者的交互作用均无显著差别(P＞0.05);(2)不同心率间比较,心率≤65次/min时图像质量评分较高(P＜0.05);(3)不同扫描速度比较,0.5 s/r时,图像质量评分较高(P＜0.05);(4)不同重组算法之间比较:重组算法为Burst-4和Burst-2时,图像质量评分较高(P＜0.05),但两者之间差异无统计学意义(P＞0.05);(5)心率、扫描速度及重组算法与图像质量间具有多元线性回归关系(标准化回归系数分别为-0.70794、-0.16449和0.27341,F=34.43,P＜0.0001),各回归系数具有显著性.结论 心率、扫描速度及重组算法等是影响16层螺旋CT冠状动脉成像图像质量的主要因素,可采用新型心脏动态体模进行评估.合理利用扫描参数能有效提高图像质量和检查的成功率.     

双能量CT冠状动脉和心肌成像的优化对比噪声比研究

目的:探讨应用专门软件优化双能量CT冠状动脉和心肌成像的对比噪声比的价值.材料和方法:36例可疑或已知冠心病患者接受了双源CT双能量心脏增强扫描,得到4个重建序列,序列A源自管球A;序列B源自管球B;序列C中70%的数据源自管球A,30%的数据源自管球B;序列D是依据特殊算法在每个像素点上取不同比例的序列A和序列B成分而得到.比较A、B、C、D 4组主动脉根部和左室心肌的平均CT值及标准差以及图像的平均对比噪声比.结果:B组和D组的主动脉根部平均CT值最高,分别为(552.3±74.7)Hu和(551.5±73.2)Hu,与A组和C组的差异有显著性(P<0.05).B组左室心肌CT值的平均标准差(31.9±7.4Hu)最高,与其他3组的差异有显著性(P<0.05),而其他3组间的差异无显著性(P>0.05).D组的平均对比噪声比(19.8±5.6)最高,与其他3组两两比较差异有显著性(P<0.05).结论:双能量CT心脏扫描结合专门软件既可以保留图像强化效果又可以获得低噪声,优化了对冠状动脉和心肌成像的对比噪声比.     

Inversion recovery single-shot TurboFLASH for assessment of myocardial infarction at 3 Tesla

PURPOSE: The aim of the study was to assess the diagnostic accuracy of imaging myocardial infarction with a single-shot inversion recovery turbofast low-angle shot (SS IR turboFLASH) sequence at 3.0 Tesla in comparison with an established segmented inversion recovery turboFLASH sequence at 1.5 Tesla. MATERIALS AND METHODS: Fifteen patients with myocardial infarction were examined at a 1.5 Tesla magnetic resonance (MR) System (Avanto, Siemens, Medical Solutions) and at a 3.0 Tesla MR system (TIM Trio, Siemens, Medical Solutions). Imaging delayed enhancement was started 15 minutes after application of contrast material. A SS IR turboFLASH was performed at 3.0 Tesla and compared with a segmented IR turboFLASH sequence at 1.5 and at 3.0 Tesla. The IR turboFLASH sequence at 1.5 Tesla served as reference method. Infarct volumes, contrast/noise ratio (CNR) of infarcted and normal myocardium were compared with the reference method. RESULTS: The Single-Shot IR turboFLASH technique allows imaging 9 slices during a single breath-hold. The CNR between infarction and normal myocardium of the reference method was 6.4 at 1.5 Tesla. The mean value of CNR of the IR turboFLASH sequence was 7.3 at 3.0 Tesla for the single-shot technique and 14.1 at 3.0 Tesla for the segmented technique. No significant difference was found for the CNR values of the reference technique at 1.5 Tesla and the single-shot technique at 3.0 Tesla, however for the comparison of the segmented technique at 1.5 and at 3 Tesla (P = 0.0001). The correlation coefficients of the infarct volumes, determined with the Single-Shot IR turboFLASH and the segmented IR turboFLASH technique at 3.0 compared with the reference method, were r = 0.95 (P < 0.0001) and r = 0.95 (P < 0.0001). CONCLUSION: The loss of CNR, which is caused by replacement of the segmented technique by the single-shot technique, is completely compensated by the approximately 2-fold CNR increase at the higher field strength. The IR turboFLASH technique at 3.0 Tesla IR can be used as a single-shot technique with acquisition of 9 slices during a single breath-hold without loss of diagnostic accuracy compared with the segmented technique at 1.5 Tesla.     

Fast, three-dimensional free-breathing MR imaging of myocardial infarction: a feasibility study.

Imaging delayed hyperenhancement of myocardial infarction is most commonly performed using an inversion recovery (IR) prepared 2D breathhold segmented k-space gradient echo (FGRE) sequence. Since only one slice is acquired per breathhold in this technique, 12-16 successive breathholds are required for complete anatomical coverage of the heart. This prolongs the overall scan time and may be exhausting for patients. A navigator-echo gated, free-breathing, 3D FGRE sequence is proposed that can be used to acquire a single slab covering the entire heart with high spatial resolution. The use of a new variable sampling in time (VAST) acquisition scheme enables the entire 3D volume to be acquired in 1.5-2 min, minimizing artifacts from bulk motion and diaphragmatic drift and contrast variations due to contrast media washout.     

Papillary muscle involvement in myocardial infarction: initial results using multicontrast late-enhancement MRI

We hypothesized that multicontrast late-enhancement (MCLE) MRI would improve the identification of papillary muscle involvement (PM-MI) in patients with myocardial infarction (MI), compared with conventional late gadolinium enhancement (LGE) MRI using the inversion recovery fast gradient echo (IR-FGRE) technique. Cardiac LGE-MRI studies using both MCLE and IR-FGRE pulse sequences were performed on a 1.5 Tesla (T) MRI system in 23 patients following MI. In all patients, PM-MI was confirmed by the diagnostic criteria as outlined below: (a) the increased signal intensity of PM was the same or similar to that of adjacent hyper-enhanced left ventricular (LV) infarct segments; and (b) the hyper-enhanced PM region was limited to the PM area defined by precontrast cine images of steady-state free precession (SSFP). Visual contrast score was rated according to the differentiation between LV blood pool and hyper-enhanced infarct myocardium. Quantitative contrast-noise ratios (CNR) of infarct relative to blood pool and viable myocardium were also measured on MCLE and IR-FGRE images. Of these 23 patients, 13 studies demonstrated primarily involvement of the territories of the right coronary (RCA, 8 patients) and/or left circumflex (LCX, 5 patients) arteries and 10 involved the territories of left anterior descending artery (LAD) with some LCX involvement. Although both IR-FGRE and MCLE determined the presence and extent of LV MI, better visual contrast scores were achieved in MCLE (2.9 ± 0.3) compared with IR-FGRE (1.6 ± 0.8, P < 0.001). The CNRs of infarct relative to LV blood pool showed a significant statistical difference (n = 23, P < 0.00001) between MCLE (16.2 ± 7.2) and IR-FGRE images (4.8 ± 4.1), which is consistent with the result of visual contrast scores between infarct and LV blood pool. The CNRs of infarct versus viable myocardium did not demonstrate a significant statistical difference (n = 23, P = 0.61) between MCLE (14.4 ± 7.0) and IR-FGRE images (13.6 ± 6.1). MCLE clearly demonstrated PM-MI in all cases (100%, 23/23) while only 39% (9/23) could be visualized on the corresponding IR-FGRE images. In conclusion, MCLE imaging provides better contrast between blood pool and infarct myocardium, thus improving the determination of PM-MI.     

A fast navigator-gated 3D sequence for delayed enhancement MRI of the myocardium: comparison with breathhold 2D imaging

PURPOSE: To develop a rapid navigator-gated three-dimensional (3DNAV) delayed-enhancement MRI (DE-MRI) sequence for myocardial viability assessment, and to evaluate its performance with breathhold two-dimensional (2DBH) DE-MRI sequence as the reference standard. MATERIALS AND METHODS: 2DBH DE-MRI was initiated 10 minutes after contrast administration and followed by 3DNAV DE-MRI in 23 patients at 1.5 T. Comparison was performed using three qualitative criteria (image quality score, diagnostic outcome, relative diagnostic confidence score) in all patients, and three quantitative criteria (infarct volume, infarct signal-to-noise ratio [SNR(inf)], and infarct-viable myocardium contrast-to-noise ratio [CNR(inf-myo)]) in patients with hyperenhanced myocardium. RESULTS: Compared to 2DBH DE-MRI, 3DNAV DE-MRI provided slightly better image quality, the same final diagnostic outcomes, and better relative diagnostic confidence score with 79% SNR(inf) improvement (P = 0.002) and 90% CNR(inf-myo) improvement (P = 0.004) in 39% less scan time (414 +/- 118 seconds for 2DBH and 251 +/- 93 seconds for 3DNAV). The measured infarct volumes demonstrated excellent correlation (18.9 +/- 19.0 mL for 2DBH DE-MRI vs. 17.6 +/- 19.0 mL for 3DNAV DE-MRI, r(2) = 0.998, P < 0.001, N = 7) and narrow limits of agreement (-1.3 +/- 1.8 mL). CONCLUSION: 3DNAV DE-MRI provides improved image quality and similar infarct detection in less scan time compared to the standard 2DBH DE-MRI.     

双时相3D SSFP 成像技术在先天性心脏病诊断中的应用初探

目的：探讨双时相三维稳态进动快速成像序列（3DSSFP）对先天心脏病的诊断价值。方法：60例平均心率108次／分的先天性心脏病患儿行收缩末期和舒张中晚期的双时相3D SSFP成像,对图像质量及对比噪声比进行分析比较。结果：心电触发收缩期延迟时间为180～300ms,平均（235．41士35．59）ms;舒张期延迟时间为384～550ms,平均（443．77土50．81）ms。3DSSFP收缩期图像上显示心内结构及肺静脉、上下腔静脉的清晰度优于舒张期,两者间图像质量的差异有统计学意义（P〈o．05）。舒张期图像上对无狭窄主动脉及肺动脉的显示清晰度高于收缩期,但两者间差异无统计学意义（P〉o．05）。收缩期图像上心内结构的对比噪声比（CNR）均高于舒张期,且两者比较差异有统计学意义（P〈0．05）。上腔静脉及下腔静脉在收缩期图像上的CNR均高于舒张期,但仅下腔静脉CNR的差异有统计学意义（P〈0．05）;主动脉和肺总动脉则在舒张期图像上的CNR高于收缩期,但两者比较差异无统计学意义（P〉0．05）。伴有肺动脉辫及辫下狭窄的肺动脉分支在收缩期的显示率（39．1％）明显低于舒张期（73．9％）。结论：双时相3DSSFP综合利用收缩期和舒张期不同时相的成像优势,能更准确地诊断先天性心脏病患儿的心内及心外大血管结构的畸形。     

Phase-sensitive inversion-recovery MR imaging in the detection of myocardial infarction

PURPOSE: To prospectively determine if phase-sensitive inversion-recovery (IR) magnetic resonance (MR) imaging eliminates the need to find the precise inversion time (TI) to null the signal of normal myocardium to achieve high contrast between infarcted and normal myocardium. MATERIALS AND METHODS: Informed consent was obtained from each patient for this prospective MR imaging research study, which was approved by the institutional review board. Twenty patients (16 men; four women; mean age, 56 years +/- 12.3) who experienced Q-wave myocardial infarction 2 weeks earlier were examined with a 1.5-T MR system 10 minutes after administration of 0.1 mmol per kilogram of body weight gadobenate dimeglumine. To determine the optimal TI, a TI scout sequence was used. A segmented two-dimensional IR turbo fast low-angle shot (FLASH) sequence and a segmented two-dimensional IR true fast imaging with steady-state precession (FISP) sequence that produces both phase-sensitive and magnitude-reconstructed images were used at TI values of 200-600 msec (TI values were varied in 100-msec steps) and at optimal TI (mean value, 330 msec). Contrast-to-noise ratios (CNRs) of normal and infarcted myocardium and the area of infarcted myocardium were determined. Magnitude-reconstructed IR turbo FLASH images were compared with magnitude-reconstructed and phase-sensitive IR true FISP images. Two-tailed unpaired sample Student t test was used to compare CNRs, and two-tailed paired-sample Student t test was used to compare area of infarction. RESULTS: Mean CNR of images acquired with IR turbo FLASH and IR true FISP (phase-sensitive and magnitude-reconstructed images) at optimal TI (mean value, 330 msec) were 6.6, 6.2, and 6.1, respectively. For a TI of 200 msec, CNR values were -4.3, -4.0, and 7.2, respectively; for TI of 600 msec, CNR values were 3.1, 3.3, and 4.3, respectively. Area of infarcted myocardium was underestimated on magnitude-reconstruction images (P = .002-.03) for short TI values (ie, 200 msec) for both sequences and for a TI of 300 msec for IR true FISP but not on phase-sensitive reconstructed IR true FISP images when compared with IR turbo FLASH images obtained at optimal TI. CONCLUSION: Phase-sensitive image reconstruction results in reduced need for precise choice of TI and more consistent image quality.     

Inversion-recovery single-shot cardiac MRI for the assessmentof myocardial infarction at 1.5 T with a dedicated cardiac coil

Objective The aim of this study was to assess the diagnostic accuracy of imaging myocardial infarction with a two-dimensional (2D) single-shot inversion-recovery (IR)-gradient-echo (GE) sequence compared with a standard 2D segmented IR-GE sequence at 1.5 T using a dedicated cardiac coil. Methods 22 patients with myocardial infarction documented in the past 3-12 months were examined at 1.5 T using a 5 channel cardiac coil. Imaging of delayed enhancement was performed 15 min after administration of 0.2 mmol of gadopentetate dimeglumine per kilogram of body weight. Immediately after completion of the single-shot sequence, which allows for coverage of the entire ventricle during a single breath-hold with nine slices, the segmented IR sequence was started. Infarct volumes, infarct transmurality and contrast-to-noise ratios (CNRs) of infarcted and healthy myocardium were compared between both techniques. Results Despite a moderate, non-significant loss of CNR (CNR(single-shot IR)=31.2±4.1; CNR(segmented IR)=37.9±4.1; p=0.405), the 2D single-shot technique correctly determined infarct size when compared with the standard 2D segmented IR-GE sequence. Assessment of both infarct volume (r=0.95; p<0.0001) and transmurality (r=0.97; p<0.0001) is possible, with excellent correlation of both techniques. Conclusion Single-shot delayed enhancement imaging during a single breath-hold is feasible at 1.5 T with the use of a dedicated cardiac coil. Despite a moderately lower CNR, the single-shot technique allows for fast and accurate determination of infarct size with high spatial resolution and has the potential to reduce electrocardiogram and breathing artefacts.     

Phase-sensitive inversion recovery (PSIR) single-shot TrueFISP for assessment of myocardial infarction at 3 tesla

PURPOSE: The aim of the current study was to show if contrast-to-noise ratio (CNR) could be improved without loss of diagnostic accuracy if a phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence is used at 3.0 T instead of 1.5 T. MATERIAL AND METHODS: Ten patients with myocardial infarction were examined on a 1.5 T magnetic resonance (MR) system (Avanto, Siemens Medical Systems) and at a 3.0 T MR system. Imaging delayed contrast enhancement was started 10 minutes after application of contrast material. A phase-sensitive inversion recovery (PSIR) single-shot TrueFISP sequence was used at 1.5 and 3.0 T and compared with a segmented IR turboFLASH sequence at 1.5 T, which served as the reference method. Infarct volumes and CNR of infarction and normal myocardium were compared with the reference method. RESULTS: The PSIR Single-Shot TrueFISP technique allows for imaging nine slices during a single breathhold without adaptation of the inversion time. The mean value of CNR between infarction and normal myocardium was 5.9 at 1.5 T and 12.2 at 3.0 T (magnitude images). The CNR mean value of the reference method was 8.4. The CNR mean value at 3.0 T was significantly (P = 0.03) higher than the mean value of the reference method. The correlation coefficients of the infarct volumes, determined with the PSIR single-shot TrueFISP technique at 1.5 T and at 3.0 T and compared with the reference method, were r = 0.96 (P = 0.001) and r = 0.99 (P = 0.0001). CONCLUSION: The use of PSIR single-shot TrueFISP at 3.0 T allows for accurate detection and assessment of myocardial infarction. CNR is significantly higher at 3.0 T compared with 1.5 T. The PSIR single-shot technique at 3.0 T provides a higher CNR than the segmented reference technique at 1.5 T.     

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.     

心肌梗死延迟增强三维与二维MR成像对比研究

目的 比较屏气三维快速小角度激励序列(3D-FLASH)延迟增强扫描与多次屏气二维快速FLASH(2D-turboFLASH)延迟增强扫描的图像质量及量化梗死面积有无差异.方法 15例心肌梗死患者行单次屏气3D-FLASH及多次屏气2D-反转恢复快速FLASH(IR-turboFLASH)延迟增强检查,以2D序列为标准,比较两者测虽心肌梗死面积比值.同时比较3D图像与2D-原始图、2D-相位敏感重组图的对比噪声比(CNR)并进行视觉评分.采用配对t检验、随机区组设计的方差分析分别对心肌梗死面积及各图像CNR进行分析.结果 3D序列测量心肌梗死面积比值(31.28%)与2D测量结果(30.91%)间差异无统计学意义(t=-0.505,P=0.621),相关性好(r=0.990).2D-相位敏感重组图CNR较其他两者低(3D、2D-原始图及2D-相位敏感重组图CNR分别为43.43±20.67、34.10±14.29和7.59±2.59),且差异具有统计学意义(F=24.376,P<0.01).但视觉评分2D-相位敏感重组图显示正常心肌与梗死心肌对比度最好,而背景噪声最明显(3D组、2D-原始图组及2D-相位敏感图组图像总体质量评分分别为2.33、2.13和2.73,背景噪声分别为2.67、2.53和1.20).结论 屏气3D-FLASH延迟增强扫描量化心肌梗死面积准确性高,图像质量良好,适合临床运用.但受屏气及时间影响大,且需准确选择反转时间.