犬急性心肌梗死磁共振心肌灌注及电影成像实验研究

目的　采用MR快速序列研究急性心肌梗死的首过灌注特点及心功能改变。材料与方法　犬心肌梗死模型 9只 ,均进行T1WI磁化准备梯度回波序列 (TurboFLASH)首过灌注扫描及MR电影成像 (cine MR) ,完成检查后处死 ,分析心肌首过灌注特点及局部心功能变化 ,并与病理检查比较。结果　首过灌注时梗死心肌表现为灌注缺损 ,信号强度 时间曲线上升延缓 ,曲线斜率和峰值信号强度分别为 0 .0 2 5± 0 .0 2 0和 0 .84± 0 .2 7,较正常心肌(0 .13± 0 .0 80和 2 .0 2± 0 .99,P <0 .0 0 0 1)明显下降 ,峰值时间和曲线上升时间分别为 37.78± 11.90s和 32 .70±14 .0 9s,较正常心肌 (17.14± 6 .0 6s和 14 .2 8± 5 .14s,P <0 .0 0 0 1)明显延长。延迟期正常心肌信号强度下降 ,而梗死心肌仍呈上升趋势。首过灌注中灌注缺损面积与TTC染色一致。梗死节段室壁运动及室壁厚度异常。结论　MR首过灌注成像可反映病变心肌组织血流灌注信息 ,cine MR能测定节段室壁功能。结合首过灌注和心功能分析 ,可对梗死心肌在形态学和功能学两方面进行定性、定量分析 ,有助于评价梗死心肌活力     

正常成人心肌MR灌注成像的初步研究

目的: 探讨利用MR心肌首过灌注及延迟增强方法评价正常成人心肌灌注特点的价值.材料和方法: 对15例正常志愿者进行MR首过灌注、延迟增强成像及cine-MR成像检查,绘制时间-信号强度曲线.结果: 正常左室前、侧、后壁心肌和室间隔时间-信号强度曲线上升时间,曲线上升斜率,对比增强率及延迟信号强度无统计学差异.结论: 正常成人心肌MR灌注成像的特点对利用MR心肌灌注成像诊断心肌病变具有重要的价值.     

磁共振心肌灌注成像急性心肌梗死的实验研究

目的 研究猪急性心肌梗死的首过灌注和延迟时相MRI特点.方法 猪心肌梗死模型12只,均进行快速梯度回波序列(FGREET)首过灌注扫描及反转恢复梯度回波序列(MDE)延迟时相扫描.扫描后处死,分析心肌首过灌注和延迟时相特点,并与病理检查对照.结果 9例(75%)首过灌注时梗死心肌表现为灌注减低,其信号强度显著低于周围心肌,10例(83.33%)延迟期梗死心肌表现为延迟强化,而正常心肌信号强度下降,低于梗死心肌.结论 MR心肌灌注成像可有效检测急性心肌梗死的梗死心肌以及其程度和范围.     

MR灌注成像在肺栓塞诊断中的应用

目的探讨MR二维快速扰相梯度回波序列（2DFSPGR）显示肺实质灌注的可能性,以及在实验性肺栓塞中的应用价值。方法11只在体犬肺栓塞模型在平静呼吸下行肺MR灌注扫描,定性及定量评价图像质量,与病理解剖对照分析肺灌注扫描诊断肺栓塞的敏感性。结果10只犬的MR图像质量为优良,可显示肺实质灌注情况,平均信号/噪声比（SNR）为67.4±18.0,对比度/噪声比（CNR）为40.9±14.2。正常灌注区的信号强度平均值为39.7±5.1,灌注不良区域信号强度平均值为15.6±2.1,灌注不良区域时间-强度曲线表现为峰值下降或曲线平直。结论MR肺灌注成像是诊断肺栓塞的可行方法。     

SENSE技术在急性心梗磁共振成像中的应用价值

目的　通过快速MR心脏电影及灌注成像评价急性心肌梗死组织的心肌运动及血流灌注特点 ,研究敏感编码技术在快速心脏磁共振成像中的应用价值。方法　结扎犬冠状动脉左前降支建立急性心梗模型。结合SENSE技术 6只犬分别行快速多层面多相位屏气电影扫描、快速MR心肌灌注及延迟扫描观察梗死心肌MRI特点。结果　心脏电影成像可显示犬前壁心梗区室壁运动异常 ,MR灌注成像表现为局部灌注缺损区 ,延迟扫描表现为梗死区高信号。使用SENSE技术扫描速度提高 1倍 ,且图像质量无明显变化。结论　快速MR电影及灌注成像有助于评价心肌运动及血流灌注 ,诊断急性梗死心肌。SENSE技术可提高心脏成像的时间分辨率 ,且在扫描时间不变时提高空间分辨率 ,减少运动及敏感伪影性 ,是一种行之有效的提高MRI速度的技术方法 ,在心脏成像中具有非常重要的应用价值。     

磁共振心肌灌注成像及延迟成像检测冠心病心肌缺血的临床研究

目的 探讨MR心肌灌注成像(PI)联合延迟扫描成像检测梗死心肌的价值.资料与方法 对18例经冠状动脉造影证实有冠状动脉狭窄的患者行MR首过心肌灌注及延迟扫描成像检查.分别计算低灌注节段组和正常灌注节段组灌注信号强度参数前后信号增强最大强度(SIp)、相对峰值强化率(SI%)、累积信号强度(ASI)、对比剂到达时间(t0)、强化峰值时间(t1),对比剂流入到强化峰值50%s时间(t1/2)、对比剂流入到强化峰值时间(Tp)、最大曲线上升斜率Slope(α).观察心肌低灌注节段,并与DSA结果比较.测定延迟扫描强化区与无强化区的信号强度值,计算强化区体积占心肌总体积的比值,分析强化区体积所占心肌总体积的比值与每搏输出量之间的相关性.结果 (1)心肌首过灌注成像与冠状动脉造影两种方法存在较好的相关性(X2=21.0,P＜0.05,r=0.53).(2)正常灌注节段组各参数分别为:SIp(162.8±30.2),SI%(136.2±6.6),ASI(931.4±98.1),t0(16.2±1.1),t1/2(18.5±1.4),t1(22.4±1.4),Tp(9.7±1.7),Slope(α)(16.1±1.7).低灌注节段与正常灌注节段参数SIp、SI%、ASI、t1、Tp、Slope(α)差异有统计学意义(P＜0.05),t0、t1/2差异无统计学意义(P＞0.05).SIp、SI%、Tp、Slope(α)为反映心肌首过灌注TIC的特异性参数,能敏感地反映缺血的程度.(3)延迟强化后,异常延迟强化区信号值(616.6±38.4)与正常延迟强化区信号值(304.0±69.0)差异有统计学意义(P＜0.05).异常延迟强化区体积比与患者每搏输出量呈负相关(r=-0.977,P＜0.05).结论 MR心肌PI通过灌注参数的分析可以评估梗死心肌的程度,参照延迟增强的结果,可确定梗死心肌,并计算梗死面积,是对心肌血供情况的最直接反映.     

磁共振心肌灌注成像及心肌活力分析诊断急性心肌梗死的价值

目的:研究磁共振心肌灌注成像及心肌活力分析在诊断急性心肌梗死中的价值。方法:选择37例急性心肌梗死患者作为观察组,同时选出37例无心血管疾病的正常志愿者作为对照组,均行灌注成像和心肌活力分析,观察2组相应心肌信号强度平均值、首过最大上升斜率及首过时间。结果:磁共振心肌灌注成像延迟期观察组梗死心肌的信号强度平均值为73.23±35.24,对照组正常心肌(对应观察组梗死区)为17.99±8.15,2组对比差异具有统计学意义(P<0.01);观察组梗死心肌的首过最大上升斜率平均值为32.85±20.69,对照组正常心肌(对应观察组梗死区)为44.68±23.60,2组对比差异具有统计学意义(P<0.01)。观察组患者心肌梗死区首过时间平均为(5.04±1.74)s,对照组正常心肌(对应观察组梗死区)为(2.82±1.82)s,2组对比差异具有统计学意义(P<0.01)。结论:磁共振心肌灌注成像及心肌活力分析可用于诊断急性心肌梗死。     

梗死心肌的MRI评价及病理对照实验研究

目的　通过MR影像与病理对照的方法明确心肌梗死后 7～ 10dMRI延迟强化区与梗死心肌的关系 ,以期为MRI评价心肌活性提供病理依据。方法　利用 6只猪无再灌注和再灌注的心肌梗死模型 ,行短轴面MR心肌延迟强化扫描。扫描结束后将心脏离体 ,沿短轴面将心脏切成断面行氯化三苯基四氮唑 (TTC)染色。比较心肌梗死区和正常对照区的延迟强化信号强度的差异 ;比较相应层面的MRI延迟强化区和TTC染色所示梗死区的关系。结果　在心肌梗死的 7～ 10d ,无论有无再灌注 ,MR延迟强化扫描均可见心肌梗死区信号较正常对照区明显升高 ,无再灌注组梗死区信号( 2 0 81± 6 49)是正常对照区 ( 2 68± 1 10 )的 7 76倍 (t =11 68,P <0 0 1) ,再灌注组梗死区信号( 14 2 8± 1 64)是正常对照区 ( 1 44± 0 52 )的 9 92倍 (t =3 1 69,P <0 0 1) ;无再灌注组的延迟强化区[占同层面左室面积的百分率为 ( 15 49± 6 0 7) % ]与梗死心肌 [( 14 95± 7 3 6) % ]一致 (t =-0 78,P>0 0 5) ,再灌注组的延迟强化区 [( 12 52± 5 93 ) % ]包括梗死区 [( 11 13± 5 81) % ]和梗死周围区 ,过度估计梗死心肌范围约 12 47% (t =-14 48,P <0 0 1)。结论　在心肌梗死的 7～ 10d ,MR延迟强化扫描可较准确地反映梗死心肌的范围     

Gd-DTPA动态增强MRI评价心肌微血管损伤

目的：探讨Gd-DTPA动态增强MRI评价心肌微血管损伤的可行性。方法：制作急性犬心肌梗死动物模型，在活体上用放射微球^99Tc—MAA测量心肌血流量，0．5％伊文蓝染色区分缺血心肌；心脏离体后用3％TTC染色区分梗死心肌，SP免疫组化染色观察心肌微血管并计算微血管体积分数。犬离体心脏左冠状动脉插管后作MRI平扫及Gd—DTPA动态增强扫描，测量正常、缺血和梗死心肌的信号强度，绘制时间-信号强度曲线。结果：在T1WI上，心肌信号强度无明显差异；在T2WI上，病变心肌信号强度较正常增高；Gd-DTPA灌注动态增强扫描，正常心肌时间-信号强度曲线呈下降形，危险心肌呈上升形，梗死心肌呈平直形，灌注晚期病变区呈明显环状强化。正常、危险和梗死心肌血流量、微血管体密度差异显著。结论：急性心肌梗死后心肌间质水肿、心肌含水量增加致T2WI信号增高。Gd-DTPA动态增强时间-信号强度曲线上升的斜率及峰值可以反映心肌微血管损伤及组织水肿的程度。     

猪心梗模型MRI心肌首过灌注实验研究

目的 探讨缺血心肌灌注以及局部心肌的存活情况. 方法 制备成功的10只猪心梗模型分别于术前及术后24 h、72 h及1周行MRI心肌首过灌注检查,MRI检查完后处死实验猪,行TTC染色及病理检查.结果 符合实验研究10只猪术前MRI心肌首过期灌注未见灌注减低或缺损,术后8只见心肌灌注缺损和减低,灌注缺损区其灌注曲线未见明显的灌注峰,在正常心肌灌注峰值时间为低灌注表现,后期曲线呈逐渐上升表现;灌注缺损周围心肌其灌注曲线峰值信号强度低于正常侧壁和下壁心肌(P<0.05);灌注曲线峰值时间较正常侧壁和下壁心肌延迟(P<0.05).灌注缺损区TTC染色及病理均可见心肌坏死,灌注减低区见间质局灶水肿、心肌纤维水肿变性. 结论 MRI心肌首过灌注成像结合灌注曲线分析可以评价心肌活性和缺血情况.     

Assessment of myocardial viability after myocardial infarction

Conclusions  The data presented above suggest that assessment of myocardial viability after MI, particularly in those patients with severe LV dysfunction, is important for the identification of those with the highest risk, in whom revascularization can be of clinical benefit. There is growing and consistent evidence that patients with relatively large areas of dysfunctional but viable myocardium after MI have improved function, symptoms, and survival with prompt revascularization compared with medical therapy alone. Most importantly, long-term survival with revascularization in these patients is comparable with that achieved with cardiac transplantation. There are several methods available to the clinician with which to investigate the presence of tissue viability, and the evidence suggests that the scintigraphic approaches are the most sensitive. These observations suggest that noninvasive investigation of the amount of ischemic myocardium should be an important component of the diagnostic evaluation of patients with severe LV dysfunction after MI. This approach will likely enhance the often difficult process of selecting patients with poor cardiac function in whom revascularization will likely improve both the quality and quantity of life.     

Nitrate-augmented myocardial imaging for assessment of myocardial viability

²⁰¹Tl myocardial perfusion imaging is presently done by several possible strategies. Stress/delayed redistribution, stress/redistribution/reinjection, and rest/redistribution imaging can be useful in the clinical assessment of myocardial viability. Unfortunately, the extent of myocardial viability may still be underestimated even by ²⁰¹Tl reinjection imaging, compared with ¹⁸F-fluorodeoxyglucose positron emission tomography. ^99mTc-labeled sestamibi imaging provides results similar to those of ²⁰¹Tl imaging in the detection of coronary artery disease, but several previous studies suggest that stress/rest ^99mTc-labeled sestamibi imaging significantly underestimates myocardial viability. Recently it has been reported that the administration of nitrates, before ²⁰¹Tl reinjection, improves detection of defect reversibility. Several studies also suggested that administration of nitrates before the injection of ^99mTc-labeled sestamibi significantly improved detection of reversibility with this agent, whereas additional studies showed further that this combination improves the predictive accuracy for recovery of left ventricular function and perfusion after coronary revascularization, compared with a standard rest ^99mTc-labeled sestamibi study. Nitrate administration before the injection of ²⁰¹Tl and ^99mTc-labeled sestamibi may thus be a potentially attractive alternative for the evaluation of myocardial viability. Although the available results are encouraging, further studies are needed to evaluate the clinical value of ²⁰¹Tl and ^99mTc-labeled sestamibi imaging, in combination with nitrates, for predicting recovery of left ventricular dysfunction.     

Acute myocardial infarction during adenosine myocardial perfusion imaging

Journal of Nuclear Cardiology -     

急性心肌梗死心肌血流再灌注评价技术

TIMIFlow作为评价再灌注的方法自20世纪80年代起就一直应用于临床。TIMIFrameCount是较TIMI血流分级更为客观、更具可重复性的联系性变量指标。TMBG和TMP从心肌微血管水平对再灌注进行评价。冠脉内多普勒血流频谱变化常作为造影过程中的附加检查指标评价血管再通及心肌再灌注。同时心肌声学造影、连续心电图ST段监测、核素心肌灌注显像和心肌增强磁共振成像作为无创性的评价方法也显示出其应用价值。     

Assessment of regional myocardial function by ECG-gated myocardial SPECT]

PURPOSES: Regional myocardial functional parameters were assessed by ECG-gated myocardial SPECT analysis in normal subjects and ischemic heart diseases. METHODS: Normal subjects (13 male and 10 female) and 51 patients with chronic ischemic heart disease underwent ECG-gated myocardial SPECT. A dose of 740 MBq of 99mTc-MIBI was injected at rest, and gated SPECT was performed 60 min later. Wall motion (WM) and systolic wall thickening (WT), % tracer uptake were evaluated by quantitative gated SPECT program (QGS). Regional parameters were obtained in the 16 segments based on the functional polar map. In the normal group, standard values were evaluated in the lateral, septal, anterior and inferior regions both in male and female subjects. In the ischemic heart disease group, sensitivity and specificity of these parameters were assessed in each segment. To estimate the ability of WM and WT in detecting regional dysfunction, decreased perfusion area, which was defined as < mean - 2SD by the normal profile, was used as a standard. The receiver operating characteristics (ROC) area analysis was also performed. RESULT: In the normal profile, % tracer uptake was decreased in the anterior segments of female group, no significant difference was observed between male and female in WM and WT. WM was decreased in the septum and increased in the lateral segment. WT didn't show any difference regional difference. Sensitivity and specificity of WM were 56%/91% in the anterior, 0%/100% in the septum, 43%/87% in the inferior, 31%/85% in the lateral. WT were 67%/93% in the septum, 67%/79% in the inferior, and 59%/81% in the septum. The area under ROC curve was WM 0.63, WT 0.85 (p < 0.005 between WM and WT) in the septum, in inferior WM 0.77, WT 0.80 (p = 0.57), in anterior WM 0.86, WT 0.87 (p = 0.095), in lateral WM 0.68, WT 0.78 (p = 0.037). CONCLUSION: In normal profile, the % tracer uptake in the anterior wall decreased in females, but WM and WT did not show significant difference in each region affected this influence. The septal WM was decreased in the normal profile and ability to diagnose regional function was also decreased compared with WT. Thus, we can conclude that WT is preferable for detecting septal functional abnormality.     

急性心肌梗死再灌注治疗前后心肌血流和代谢的变化及临床意义

目的　探讨急性心肌梗死患者行经皮冠状动脉腔内成形术 (PTCA)和支架术后心肌血流、脂肪酸代谢及糖代谢的变化及其临床意义。方法　 2 2例急性心肌梗死患者 ,于发病后 4周行延迟PTCA ,术前 (急性期 )及术后 (慢性期 )分别行2 0 1 Tl、1 2 3I β 甲基碘苯脂十五烷酸 (BMIPP)SPECT显像及1 8F 脱氧葡萄糖 (FDG)PET心肌显像。将左心室分成 13个节段 ,采用 4级评分法对2 0 1 Tl、1 2 3I BMIPP显像放射性分布进行视觉评价 ,两者得分差为2 0 1 Tl BMIPP不匹配。在血流减低部位 ,定量测定1 8F FDG摄取。慢性期复查冠状动脉造影。结果　急性期心肌血流 脂肪酸代谢不匹配的节段 ,1 8F FDG摄取率明显高于匹配节段 [(76 .5± 10 .6 ) %和 (4 5 .8± 8.6 ) % ,P <0 .0 1],慢性期两者无明显差异。冠状动脉非再狭窄患者其慢性期2 0 1 Tl BMIPP不匹配 (0 .2 5± 0 .4 2 )及1 8F FDG摄取率 [(5 2 .1± 8.1) % ]较急性期 [0 .36± 0 .5 1和 (72 .8± 9.8) % ]明显降低 (P均 <0 .0 1) ;冠状动脉再狭窄患者其慢性期与急性期比较 ,2 0 1 Tl BMIPP不匹配及1 8F FDG摄取率无明显变化。结论　观察急性心肌梗死PTCA前后心肌血流 脂肪酸代谢及糖代谢的变化 ,可间接预测PTCA后再狭窄。