Myocardial perfusion single photon computed tomography: An Atlas

The purpose of this Teaching Atlas is to provide the reader with both image recognition and an understanding of the basis for myocardial perfusion single photon computed tomography (SPECT) images interpretation. The objective is to present a wide variety of myocardial perfusion cases, both relevant and to some extent in-depth, to be used by nuclear cardiologist/nuclear medicine physicians as well as trainees in cardiology, radiology and nuclear medicine. In recent years, the field of nuclear cardiology has made major advances in both radiopharmaceuticals and instrumentation. Attenuation correction techniques have and will continue to improve the diagnostic accuracy of myocardial perfusion SPECT. Several attenuation correction aspects are included in this Atlas.     

High prevalence of asymptomatically poor muscle perfusion of lower extremities measured in systemic lupus erythematosus patients with abnormal myocardial perfusion

Patients with systemic lupus erythematosus (SLE) may develop premature atherosclerosis, notably peripheral vascular disease (PVD) presenting with intermittent claudication or gangrene. Therefore, it is important to investigate if high prevalence of poor muscle perfusion of lower extremities in SLE patients with abnormal myocardial perfusion is related to more cardiovascular risk factors. We used a well-established and noninvasive radionuclide method (xenon 133 muscle washout) to evaluate objectively the anterior tibial muscle perfusion of 34 SLE female patients without symptoms/signs of PVD in the lower extremities. The patients were separated into two groups according to myocardial perfusion imaging results. Meanwhile, 30 normal female controls with matched age distribution were also included for comparison. The muscle perfusion differed significantly (P <0.05) between patients (1.90±0.41 ml/100 g per min) and controls (2.91±0.50 ml/100 g per min), as well as between 18 SLE patients with abnormal myocardial perfusion (1.33±0.43 ml/100 g per min) and 16 with normal myocardial perfusion (2.26±0.45 ml/100 g per min). Based on the xenon 133 muscle washout method, we conclude that muscle perfusion in the lower extremities of SLE patients without symptoms/signs of PVD is significantly decreased and related to abnormal myocardial perfusion.     

冠状动脉造影正常的心肌梗塞患者核素心肌灌注显像

目的 :分析冠状动脉造影正常的心肌梗塞患者核素心肌灌注显像表现。　　方法 :回顾总结了 18例冠状动脉造影正常的心肌梗塞患者 99m锝 -甲氧基异丁基异腈 (99m Tc- MIBI)静息心肌断层显像。　　结果 :18例心肌梗塞患者心肌灌注显像均显示异常 ,12例有节段性缺损 ,6例未见缺损但可见心肌节段性稀疏。心肌灌注显像对心肌梗塞的定位与心电图 Q波比较 ,显示病变部位更明确。　　结论 :心肌灌注显像提供了冠状动脉造影正常的心肌梗塞患者心肌损伤部位及程度。     

延期支架置入对高血栓负荷ST段抬高急性心肌梗死预后的影响

目的研究高血栓负荷的ST段抬高急性心肌梗死（STEMI）患者血栓抽吸后,延迟置入支架对患者预后的影响。方法选取129例血栓积分评分≥2分,经皮冠状动脉球囊扩张成形术（PTCA）和（或）血栓抽吸后血栓积分评分≤2分的STEMI患者纳入本研究,随机分为即时支架组（65例）和延期支架组（64例）。结果两组患者支架置入后TIMI积分、术后2 h ST段回落≥50%比较,差异均无统计学意义;而TIMI心肌灌注分级（TMP）积分即刻支架组显著低于延期支架组,差异有统计学意义（P〈0.001）。延期支架组术后6个月较入院时左心室舒张末期容积（LVEDV）、左心室收缩末期容积（LVESV）降低,左心室射血分数（LVEF）升高,其中LVEDV降低差异有统计学意义（P〈0.05）;即时支架组6个月后较入院时LVEDV、LVESV升高,LVEF降低,其中LVESV升高（P〈0.05）和LVEF降低（P〈0.001）差异有统计学意义。术后30 d内两组间主要不良心血管事件（MACE）及主要出血事件比较,差异均无统计学意义。术后12个月时,两组心源性死亡、再发心肌梗死、靶血管血运重建比较,差异均无统计学意义（P〈0.05）,但即时支架组心力衰竭发生率较延期支架组显著增多（P〈0.05）,使得即时支架组MACE事件发生率较延期支架组显著升高（P〈0.05）。两组间比较,延期支架组住院天数较即时支架组增多,差异有显著统计学意义（P〈0.001）,且住院费用显著增多,差异有显著统计学意义（P〈0.001）。结论对于高血栓负荷的STEMI患者,经PTCA、血栓抽吸、强化抗栓处理后延迟行支架置入,可更好地改善患者的心肌灌注,减少心力衰竭的发生,从而使MACE事件发生率下降,但延期支架置入术患者的住院天数和住院费用会相应增加。     

急性心肌梗死急诊介入治疗后心肌组织灌注与心功能的关系

目的:探讨心肌梗死溶栓治疗临床试验(TIMI)心肌灌注分级(TMP)、ST段最大偏移(maxSTE)评价急性心肌梗死急诊介入治疗后心肌组织灌注程度与左心室功能状态的关系。 方法:65例急性心肌梗死患者急诊介入治疗后即刻采用TMP、maxSTE评价心肌灌注程度,术后用酶联免疫荧光法检测N端脑钠肽水平;住院期间超声心动图测定左心室射血分数值;临床评估Killip分级。 结果:无心肌灌注患者(TMP 0-1级)与心肌再灌注患者(TMP 2-3级)比较:N端脑钠肽水平升高、Killip分级增加,均有极显著性差异(P<0.01),左心室射血分数值有降低趋势,但差异无显著性;TMP 0-1级、maxSTE高危为住院期间心力衰竭的独立危险因子。 结沦:TMP、maxSTE评价的心肌组织灌注程度与左心室功能状态有关,TMP、maxSTE能预测住院期间心力衰竭的发生。     

Myocardial perfusion assessed by contrast echocardiography correlates with angiographic perfusion parameters in patients with a first acute myocardial infarction successfully treated with angioplasty

BACKGROUND:

Angiographic flow in an epicardial artery does not define perfusion at the microvascular level.

AIM:

To compare myocardial contrast echocardiography (MCE) with angiographic methods of assessing microvascular reperfusion in patients with acute myocardial infarction (AMI).

METHODS:

One hundred consecutive patients with a first ST segment elevation myocardial infarction and single-vessel disease were successfully treated with primary percutaneous coronary intervention. Regional contrast score index (RCSI), corrected Thrombolysis In Myocardial Infarction (TIMI) frame count (cTFC), TIMI myocardial perfusion grade (TMPG) and myocardial blush grade were evaluated.

RESULTS:

Among 717 asynergic segments on MCE, 168 revealed a lack of perfusion. TMPG and cTFC correlated significantly with RCSI (P=0.031 and P=0.027, respectively). Myocardial blush grade did not correlate with RCSI (P=0.067). Patients with anterior AMI had significantly more segments with a perfusion defect on MCE than patients with inferior AMI (P=0.0001).

CONCLUSIONS:

MCE results correlate with angiographic methods of perfusion assessment such as TMPG and cTFC. Anterior AMI is associated with a greater extent of perfusion defect. MCE results correlate also with recovery of systolic left ventricular function and clinical outcome at six month follow-up.     

Time-to-treatment significantly affects the extent of ST-segment resolution and myocardial blush in patients with acute myocardial infarction treated by primary angioplasty.

AIMS: The prognostic role of time-to-treatment in primary angioplasty is still a matter of debate. The aim of our study was to evaluate the relationship between time-to-treatment and myocardial perfusion in patients with ST-segment-elevation myocardial infarction (STEMI) treated by primary angioplasty. METHODS AND RESULTS: Our study population consisted of 1072 patients with STEMI treated by primary angioplasty from 1997 to 2001. Myocardial perfusion was evaluated by using ST-segment resolution and myocardial blush grade. Time-to-treatment was defined as the time from symptom-onset to the first balloon inflation. Time-to-treatment was significantly associated with the extent of ST-segment resolution, myocardial blush grade, enzymatic infarct size, and 1-year mortality. After adjustment for baseline confounding factors, time-to-treatment was still associated with impaired ST-segment resolution (adjusted OR [95% CI]=1.01 [1.01-1.02], p<0.001) and myocardial blush (adjusted OR [95% CI]=1.01 [1.01-1.02], p<0.0001). CONCLUSIONS: This study shows that in patients with STEMI treated by primary angioplasty prolonged ischaemic time is associated with impaired myocardial perfusion, larger infarct size, and higher 1-year mortality. Therefore, all efforts should be made to shorten ischaemic time as much as possible to achieve better myocardial perfusion and myocardial salvage in primary angioplasty for STEMI.     

核素心肌灌注显像评价FH纯合子患者心肌血供异常临床意义初步研究

目的:利用核素心肌灌注显像(MPI)研究家族性高胆固醇血症(FH)纯合子患者病情进展对心肌血供的影响及临床意义。方法:以经染色体检测确诊并来我院检查的28例FH纯合子患者为研究对象,均行药物负荷/静息MPI,根据心肌血供异常与否,将患者分成两组,并对两组患者的基本资料、血脂水平及心肌血流灌注情况进行对比分析,其中8例患者随诊1~2年。结果:28例FH患者,男性17例,女性11例,平均年龄12.12岁,TC(16.00±2.92)mmol/L,LDLC(13.82±2.73)mmol/L;MPI示15例阴性(男/女=11/4例),13例阳性(男/女=6/7例)。负荷试验中6例出现心电图ST段下移性改变。MPI显示:13例MPI阳性患者共计221个心肌节段中,29个节段出现心肌缺血(13.1%);其中左前降支、回旋支、右冠状动脉供血区分别有21个节段(21/29,72.4%)、5个节段(5/29,17.2%)、3个节段(3/29,10.3%)。MPI阳性与阴性两组中,患者的年龄(P=0.621)、身高(P=0.219)、体质量(P=0.847)、体质量指数(P=0.155)、治疗时间(P=0.189)、性别(P=0.246)、心电图ST段有无下移(P=0.372)、TC(P=0.088)、LDL-C(P=0.082)、TG(P=0.062)、HDL-C(P=0.652)均差异无统计学意义。8例随诊患者复查MPI结果提示:4例原无心肌缺血现仍为阴性;4例原有心肌缺血者,3例心肌缺血范围和程度均无明显变化,1例因心肌缺血程度加重导致心力衰竭后死亡。结论:FH纯合子患者心肌缺血好发于左前降支供血区,且患者的年龄、身高、体质量、治疗时间、血脂等因素在MPI阳性组与阴性组中的差异无统计学意义;最好早期对FH纯合子患者行MPI以评估心血管病危险度分层、患者治疗效果和预后。     

超声二次谐波心肌声学造影评价心肌的血流灌注

目的探讨心肌声学造影对冠状动脉(冠脉)病变的诊断价值。 方法静脉注射声学造影剂利声显(levovist),通过超声二次谐波技术获取心肌灌注图像,对比冠脉造影显示的冠脉支配区域的心肌灌注与超声心肌声学造影获取的心肌灌注类型的关系。按心肌灌注积分指数将异常冠脉分为3组,心肌灌注积分指数1分(A组,27支),2分≥心肌灌注积分指数＞1分(B组,24支),＞2分(C组,33支)。 结果心肌灌注积分指数与冠脉狭窄度呈中度正相关(r＝0.75,P＜0.001),3组病人的冠脉狭窄程度、心肌灌注积分指数明显差异(P＜0.001)。冠脉狭窄度＜75%者,病人室壁灌注多为正常,随着冠脉狭窄程度加重,室壁灌注出现异常。 结论静脉心肌声学造影是反映心肌灌注的有效方法,能够反应冠脉血流的改变及微循环结构的完整性变化,从而弥补了冠脉造影仅能显示心外膜下的冠脉而无法观察毛细血管水平心肌灌注的缺限。     

多巴酚丁胺负荷~(99m)Tc-MIBI心肌断层显像诊断冠心病的价值

56例多巴酚丁胺负荷~(99m)锝-甲氧基异丁基异腈(~(99m)Tc-MIBI)门控心肌灌注断层显像(DBA-SPECT),并进行多巴酚丁胺负荷心电图(DBA-ECG)及平板运动心电图.21例行冠脉造影.DBA负荷血液动力学效应曲线与平板运动试验之曲线相似.DBA-SPECT诊断冠心病的敏感性、特异性、准确率分别为87.5%、76.9%、81.0%;DBA-ECG诊断冠心病的敏感性、特异性、准确率分别为75.0%、92.3%、85.0%;平板运动心电图诊断冠心病的敏感性、特异性、准确率分别为87.5%、46.2%、61.9%.表明DBA-SPECT是诊断冠心病的一种具有较高敏感性和特异性的方法.且安全可靠,可部分代替运动负荷试验.     

L’échographie de contraste pour analyse de la perfusion myocardique : une vieille technique pleine d’avenir ?

Myocardial perfusion assessment with contrast echocardiography has been studied for more than 25 years. It is a feasible and safe technique. Rather it has an additional value in pharmacologic stress test remains unclear. However, with adequate settings (using both low and very low mechanical index), perfusion analysis can be very useful for the diagnosis of apical thrombus or tumor, viability assessment, and acute coronary syndrome with non-informative ECG.     

心肌灌注显像中潘生丁试验与踏车运动试验对冠心病诊断价值的比较

为比较潘生了试验和踏车运动试验心肌灌注平面显像诊断冠心病的灵敏度和特异性，我们将100例胸痛患者随机分为两组，分别进行两种试验介人心肌灌注显像，并与冠状动脉造影结果对照。结果：两种介入性试验平面心肌灌注显像，对冠心病诊断的灵敏度分别为：94.59％和92％；特异性分别为80.95％和80％；且对识别冠脉单支，双支，三支管的灵敏度，诊断不同冠脉分支病变的灵敏度，以及检出相应病变血管的灵敏度等各项指标，两组之间对照均无显著性差异。表明：潘生丁试验和踏车运动试验介人心肌灌注平面显像，均可为临床冠心病的诊断和病变的定位提供较可靠的依据。     

Abnormal myocardial perfusion and risk of heart failure in patients with type 2 diabetes mellitus

BACKGROUND:

Diabetes is a major risk factor for heart failure (HF), although the pathophysiological processes have not been clarified.

OBJECTIVE:

To determine the prevalence of HF and of abnormal myocardial perfusion in diabetic patients evaluated using technetium (99m) sestamibi single-photon emission computed tomography.

METHODS:

An observational cross-sectional study was conducted that included patients with type 2 diabetes mellitus who underwent echocardiography to diagnose HF and a pharmacological stress test with intravenous dipyridamole to examine cardiac scintigraphic perfusion abnormalities. Clinical and biochemical data were also collected.

RESULTS:

Of the 160 diabetic patients included, 92 (57.6%) were in HF and 68 (42.5%) were not. When patients were stratified according to the presence of abnormal myocardial perfusion, those with abnormal perfusion had a higher prevalence of HF (93%) than those with normal perfusion (44.4%) (P<0.0001). Patients with HF weighed more (P=0.03), used insulin less frequently (P=0.01), had lower total cholesterol (P=0.05) and high-density lipoprotein cholesterol concentrations (P=0.002), and a greater number of their myocardial segments showed abnormal perfusion (P≤0.001). More HF patients had a history of myocardial infarction (P<0.001) compared with those without HF. In a logistic regression analysis, the number of segments exhibiting abnormal myocardial perfusion was an independent risk factor for HF.

CONCLUSIONS:

The prevalence of HF in diabetic patients was high and HF predominantly occured in association with myocardial ischemia.     

闭塞冠状动脉供血区域心肌存活性的评价

目的：探讨慢性闭塞冠状动脉供血区域心肌的存活性。方法：对冠状动脉造影证实的冠状动脉慢性闭塞患者４６ 例，分别行低剂量多巴酚丁胺（ＤＯＢ）加硝酸甘油（ＮＴＧ）负荷二维超声心动图（２－ＤＥ）试验及运动加ＮＴＧ介入９９ｍ Ｔｃ－ＭＩＢＩ心肌单光子发射计算机体层摄影术（ＳＰＥＣＴ）显像。结果：４６ 例患者造影发现慢性闭塞冠状动脉５０ 支，根据是否有心肌梗死病史分为无梗死组１６例，梗死组３０ 例，负荷２－ＤＥ法判断无梗死组闭塞冠状动脉供血区均有存活性，心肌显像判断上述部位存在明显缺血，但仍具有存活性，两种方法结果一致。负荷２－ＤＥ法判断梗死组４０％ 患者（１２／３０）梗死区域有存活性，心肌显像判断梗死组２６．７％ 患者（８／３０）梗死区有存活性，两种检测方法的结果相符。结论：无心肌梗死病史患者闭塞冠状动脉供血区域有明显缺血，但均具有存活性，部分陈旧性心肌梗死患者相关动脉虽慢性闭塞，但梗死区仍具有存活性。     

凯时对急性心肌梗死急诊经皮冠状动脉介入治疗后心肌灌注的影响

目的评价急诊经皮冠状动脉介入治疗（PCI）术联合应用凯时（前列腺素E1）对术后心肌灌注的影响。方法将58例接受急诊PCI治疗且符合术前梗死相关血管完全闭塞（血流TIMI0级或1级）,PCI治疗后梗死相关血管达到血流TIMI3级的急性心肌梗死患者随机分为凯时组28例和对照组30例。比较两组临床特征、心肌呈色分级（MBG）、心电图ST段回落指数（sumSTR）及住院期间主要心血管事件、左室射血分数。结果两组基础临床情况及造影特征无明显差异。凯时组心肌呈色分级2／3级获得率明显增高（71．4％vs43．3％,P〈0．05）,术后心电图ST段回落指数（sumSTR）≥50％的比例更高（82．1％vs53．3％,P〈0．05）。心肌梗死1周后射血分数亦高于对照组（57．3％±5．4％vs47．2％±7．2％,P〈0．05）。两组住院期间主要心血管事件差异无统计学意义（P〉0．05）。结论急性心肌梗死患者在急诊PCI基础上,联合凯时治疗可改善心肌灌注,改善患者心功能,近期疗效好,无不良反应。     

High prevalence of asymptomatically poor muscle perfusion of lower extremities measured in type II diabetes patients with abnormal myocardial perfusion

Foot problems are the most common cause of hospital admission in patients with type II diabetes mellitus (DM). Poor muscle perfusion of lower extremities is thought to be the major component in the pathogenesis of foot problems. Therefore, it is important and interesting to investigate if high prevalence of poor muscle perfusion of lower extremities in type II DM patients with abnormal myocardial perfusion and more cardiovascular risk factors. We used a well-established and noninvasive radionuclide method (Xe-133 muscle washout) to objectively evaluate the anterior tibial muscle perfusion of 60 type II DM male patients without symptoms/signs of peripheral vascular disease (PVD) in the lower extremities. The patients were separated into groups according to the myocardial perfusion imaging results and cardiovascular risk factor survey. Meanwhile, 30 normal male controls with a matched age distribution were also included for comparison. The muscle perfusions were of significant difference (P-values <.05) between (1) 60 type II DM patients (1.84±0.43 ml/100 g/min) and 30 normal controls (2.95±0.52 ml/100 g/min), (2) 24 patients with abnormal myocardial perfusion (1.31±0.45 ml/100 g/min) and 36 patients with normal myocardial perfusion (2.24±0.48 ml/100 g/min), as well as (3) 28 patients with more cardiovascular risk factors (1.33±0.46 ml/100 g/min) and 22 patient with less cardiovascular risk factors (2.22±0.49 ml/100 g/min). Based on Xe-133 muscle washout method, we concluded that the muscle perfusion in the lower extremities of type II DM patients without symptoms/signs of PVD is significantly decreased and related to abnormal myocardial perfusion and more cardiovascular risk factors.     

Quantification of myocardial salvage by myocardial perfusion SPECT and cardiac magnetic resonance — reference standards for ECG development

In order to determine the cardioprotective efficacy of acute reperfusion therapy, assessed as myocardial salvage, in patients with acute coronary occlusion, the final myocardial infarct (MI) size needs to be related to the amount of ischemic myocardium during coronary occlusion, referred to as the myocardium at risk (MaR). There are currently several imaging approaches available for quantification of both MI size and MaR in vivo of which some have been validated both in pre-clinical and clinical settings. These methods often involve the use of either myocardial perfusion SPECT or cardiac magnetic resonance (CMR). These imaging methods could potentially be used to further develop and validate ECG methods for determination of MI size and MaR. Therefore, the aim of the present review is to give an overview of myocardial perfusion SPECT and CMR methods available for assessment of myocardial salvage by determination of MI size and MaR.     

Personalized assessment of radiation risks from the one-stop-shop myocardial 256-slice CT examination

Background

This study provides data on the cumulative life attributable risk (LAR) of radiation-induced cancer from the combination of coronary CT angiography (CCTA), dynamic CT perfusion (CTP) and delayed enhancement (DE) CT scans, required for reliable risk–benefit analysis of the one-stop-shop CCTA + CTP + DECT cardiac examination.

Methods

Monte Carlo simulation of the dynamic CTP and DECT exposures on 62 adult individuals was employed to determine radiation absorbed dose to exposed radiosensitive organs. Corresponding data for CCTA were derived using patient chest circumference and previously published data. Individual-specific LARs of cancer were estimated using organ/tissue-specific radiogenic cancer risk factors. Total LAR from CCTA + CTP + DECT scans' sequence were estimated and compared to nominal intrinsic risk of cancer.

Results

The main contribution, up to 80%, to cumulative radiation burden from CCTA + CTP + DECT scan-sequence was found to originate from the CTP scan. The total LAR from CCTA + CTP + DECT for females was found 4–6 times higher, compared to males. The mean cumulative risk of radiogenic cancer associated with the complete CCTA + CTP + DECT scan sequence was found to marginally increase the intrinsic risk for cancer induction by less than 0.6% and 0.1% for females and males, respectively.

Conclusions

The radiation risk from the 256-slice CCTA + CTP + DECT scan sequence may be considered low and should not constitute an obstacle for the clinical endorsement of the one-stop-shop cardiac CT examination, given that its clinical value has been well verified. Nevertheless, every effort should be made towards optimization of the dynamic CTP component which is the main contributor to patient radiation burden.