CT心肌灌注成像应用进展

自1972年Hounsfield发明CT至今,CT为各种疾病的诊治贡献了巨大的力量,随着多排螺旋CT的问世,其技术不断的革新,CT的探测器宽度、时间分辨率、组织分辨率及能谱成像等技术水平不断提高,使其迅速发展为心脏无创检查的重要方法之一。特别是进入了"后64排CT时代",320排CT、Brilliance iCT、双源CT和宝石CT等高端CT相继问世以来,CT设备技术突飞猛进。现已证实CT在评价冠状动脉形态学、粥样硬化斑块性质和冠状动脉钙化负荷积分等方面的应用价值,并且还能一站式完成心肌灌注。本文就CT心肌灌注方面的研究进行综述。     

结直肠癌64层螺旋CT灌注成像参数测定的可重复性研究

目的对结直肠癌64层螺旋CT灌注成像参数测定的可重复性进行评价。方法对33例结直肠癌患者进行64层螺旋CT灌注成像研究。重复测量灌注参数血流量（BF）、血容量（BV）、平均通过时间（MTT）、表面通透性（PS），比较各参数在同一观察者内及不同观察者间测定的可重复性。结果同一观察者不同时间测定的各参数均值相近，无统计学差异（P〉0．05）；不同观察者所测定的各参数均值也无显著性差别（P〉0．05）。结论结直肠癌64层螺旋CT灌注成像具有快速、无创、可重复性较好等特点，可用于评价结直肠癌的血流灌注状况。     

腺苷负荷动态CT心肌灌注定量评价冠状动脉微循环的实验研究

目的 观察腺苷对心肌灌注的影响，对比腺苷负荷前后心肌灌注变化，并得出定量指标。方法 对10只中华小型猪依次行静息态及负荷态动态CT心肌灌注成像（CT-MPI），测量左心室心肌17个节段、右冠状动脉（RCA）、左前降支（LAD）及回旋支（LCx）3支血管支配心肌，基底部、中间部、心尖部（包括心尖）3个区域及心肌各壁所属节段心肌血流量（MBF）、心肌血容量（MBV）、达峰时间（TTP）及组织通过时间（TTT）。将心肌节段分为静息组和负荷组，比较组间MBF、MBV、TTP及TTT差异。通过腺苷负荷后心肌血流灌注量化指标改变，观察腺苷对冠状动脉微循环的负荷效能。结果 静息组MBF、MBV、TTP及TTT分别为（199.82±66.24）ml/（100 ml·min）、（15.71±5.58）ml/100 ml、（6.38±2.03）s及（13.39±4.91）s；负荷组分别为（278.87±123.24）ml/（100 ml·min）、（20.91±7.66）ml/100 ml、（5.83±1.68）s及（12.53±4.49）s。相比静态组，负荷组MBF、MBV显著升高、TTP缩短（t=8.757、7.738、3.367，P均<0.05），2组TTT差异无统计学意义（t=1.743，P>0.05）。结论 腺苷可增加心肌小型猪血流灌注、缩短灌注TTP；结合动态CT-MPI，可定量分析负荷前后心肌灌注变化及程度。正常心肌组织灌注储备不受腺苷影响。     

CT心肌灌注成像技术评估存活心肌的研究进展

心肌梗死是全球范围内致死和致残的主要疾病之一,以发病急、病情变化快、病死率高为特点。1980年心肌存活性（myocardial viability）概念首次提出,随后挽救缺血心肌的冠状动脉搭桥术和介入性治疗的广泛开展,使缺血后血流再通成为可能,因此诊断心肌梗死和术前评价心肌存活性对缺血性心脏病的治疗决策以及评价再灌注治疗效果都具有很重要的临床意义。     

320排动态容积CT心肌灌注成像诊断猪急性心肌缺血再灌注损伤的实验研究

目的 评价320排CT心肌灌注成像(CTP)是否可以准确诊断猪急性心肌缺血再灌注损伤引起的心肌灌注异常.方法 8只猪通过介入球囊栓塞左冠状动脉前降支(LAD)中远段30 min后再通90 min建立再灌注损伤模型,术后行CTP扫描.检查结束后立即处死动物,取出心脏,进行氯化三苯基四氮唑(TTC)染色,分析心肌缺血再灌注损伤范围,显微镜下观察病理学改变;以病理结果为参照,测量CTP左心室短轴位二维图中损伤区、非损伤区心肌的CT值.将左心室壁分为17个节段,确定二维图、心肌透壁灌注率(TPR)图和大体病理上心肌损伤的节段数.以病理结果为金标准分别评价二维图、TPR图两组图像显示心肌损伤节段的敏感性、特异性和一致性.利用配对t检验分析损伤区和非损伤心肌CT值的差异.结果 8只猪TPR图见心尖前壁、心尖间隔灌注稀疏甚至缺损,左心室短轴位二维图中再灌注损伤区较正常心肌呈明显低密度,损伤区心肌CT值[(56.23±8.68)HU]较正常心肌[(120.57±15.36)HU]明显降低(t=8.83,P<0.01).与病理金标准对照,TPR图诊断再灌注损伤的敏感性、特异性、阴性预测值和阳性预测值分别为89.3%(25/28)、93.5%(101/108)、78.1%(25/32)、97.1%(101/104),Kappa值为0.79;而二维图的敏感性、特异性、阴性预测值、阳性预测值和Kappa值分别为85.7%(24/28)、92.6%(100/108)、75.0%(24/32)、96.2%(100/104)和0.74.结论 320排CT心肌灌注成像可用于检测猪急性心肌缺血再灌注损伤,与病理诊断一致性好.     

颅脑CT灌注成像研究进展

CT灌注成像(CTP)是一种可定量反映组织器官功能的技术,有较为广阔的临床应用前景。随着MSCT技术不断进步,CTP检查的操作流程变得相对简单,辐射剂量较前明显减少,图像质量大幅提高。CTP在脑缺血性疾病及脑肿瘤等方面研究及临床应用都取得重要进展。本文对脑CTP的原理、扫描参数的优化、临床应用及发展前景进行综述。     

CT灌注成像评价甲状腺病变

目的 探讨多排螺旋CT灌注成像(MSCTPI)在甲状腺占位性病变诊断和鉴别诊断中的临床应用价值.方法 43例符合入选标准的病例,分为良性组33例和恶性组10例,良性组包括结节性甲状腺肿亚组(17例)和甲状腺腺瘤亚组(16例),恶性组为甲状腺癌10例.采用GE LightSpeed 16排螺旋CT,常规CT平扫后动态增强扫描;绘制颈总动脉、甲状腺良性病变和甲状腺癌的时间-密度曲线(TDC),并计算各组BF、BV、MTT、PS值.对灌注参数各指标进行统计学分析.结果 颈总动脉TDC为单峰型,良性组的TDC表现为速升-缓降的小峰,恶性组TDC可分为基线段、上升段、下降段和水平段.良性组与恶性组间比较,BV、BF、MTT、PS值差异均有统计学意义(P=0.001、<0.001、0.003、<0.001);BV值和MTT值良性组各亚组与甲状腺癌组比较差异无统计学意义(P均>0.05);BF值良性组各亚组与甲状腺癌组比较差异有统计学意义(P均<0.05);PS值恶性组与结节性甲状腺肿组差异有统计学意义(P<0.05).良性结节甲状腺肿组与甲状腺腺瘤组在BF、BV、MTT、PS值比较差异均无统计学意义.结论 MSCTPI可准确反映甲状腺病变的血流特点;分析灌注参数BF、BV、MTT及PS值有利于鉴别诊断甲状腺良恶性病变.     

DECT首过心肌灌注成像的临床应用

目的 探讨双源CT(DECT)心肌灌注成像的临床应用价值.方法 选取59例接受DECT心肌灌注成像及SPECT负荷心肌显像者,根据检查结果分为A组(对照组,20例)和B组(缺血性心脏病组,39例),测量A组各心肌节段以及B组灌注缺损区、缺损周边及缺损对侧心肌CT灌注值(VNC及Overlay值).比较DECT与SPECT检出早期心肌灌注缺损(EPD)的差异,分析冠状动脉狭窄程度对两种检查方法一致性的影响.结果 A组心尖部、中间部及基底部VNC、Overlay值的差异无统计学意义(P均＞0.05).B组中DECT检出92处EPD,其中53处经SPECT证实,二者检查结果的差异无统计学意义(x2 =3.403,P=0.065),呈中等相关(r=0.533,P＜0.01).供血冠脉轻度狭窄时两种检查方法检出EDP的差异有统计学意义(x2=11.396,P＜0.01),而中度及重度狭窄时两种检查方法检出EDP的差异无统计学意义(P均＞0.05).结论 DECT首过心肌灌注成像能准确评估正常心肌及缺血心肌的灌注情况,与SPECT检查结果具有相关性,且更易检出早期、轻度心肌缺血.     

脑型血吸虫病的CT灌注成像研究

目的:运用多层螺旋CT灌注成像的方法时脑型血吸虫病进行研究,探讨脑型血吸虫病痛灶的灌注参数特性.方法:10例经临床或手术病理证实的脑型血吸虫病患者,在常规CT扫描的基础上行CT灌注成像检查.分析灌注图像,分别测量脑型血吸虫病病灶及对侧正常脑组织的脑血流量(CBV)、脑血容量(CBF)和表面通透性(PS)值.两组问CT灌注参数值的比较采用t检验.结果:10例脑型血吸虫病中,脑炎型1例,单发结节型2例,多发结节型7例.与对侧正常脑组织相比,血吸虫病灶的CBF、CBV和PS值均明显增高.结论:脑型血吸虫病病灶是一种高血流灌注、高表面通透性的病灶.     

CT灌注成像在骨肉瘤疗效评价中的应用

目的 探讨CT灌注成像(CTPI)在骨肉瘤抗血管生成治疗及化疗疗效判断中的应用价值。方法 将25例原发性骨肉瘤患者随机分为两组:化疗+抗血管生成治疗组(n=14)和化疗组(n=11),对所有病例在治疗前后行64层螺旋CT扫描,分别比较治疗前后肿瘤体积及灌注参数的差别,并对灌注参数与肿瘤微血管密度(MVD)值进行相关性分析。结果 化疗+抗血管生成治疗后,该组患者血流量(BF)、血容量(BV)、Patlak血容量(PBV)和对比剂起始时间(TTS)下降显著(P＜0.05),毛细血管通透性(PS)和对比剂峰值时间(TTP)变化不明显(P＞0.05)。化疗组患者治疗前后各项参数变化均不显著(P＞0.05)。治疗前后两组肿瘤体积改变均无统计学意义(P＞0.05)。两组BF、BV、PBV和PS值均与MVD呈正相关(P＜0.05),TTS、TTP与MVD无相关关系(P>0.05)。化疗+抗血管生成治疗组和化疗组两年生存率分别为84.71%、55.25%,两组生存曲线整体比较具有统计学意义(P＜0.05)。结论 CTPI可为观察骨肉瘤治疗后改变及判断预后提供更多的客观依据。     

Optimal timing for first-pass stress CT myocardial perfusion imaging

CT-based myocardial perfusion imaging (CTP) has been shown to accurately detect myocardial perfusion defects when compared to SPECT. When performing single-phase first-pass stress CTP, timing is of major importance. The aim of this study was to provide guidance for optimal timing of single-phase first-pass stress CTP acquisitions. 16 patients (12 male, age, 69 ± 8 years) with known or suspected coronary artery disease underwent invasive coronary angiography with fractional flow reserve (FFR) measurements using a pressure wire as well as a time-resolved CTP protocol under adenosine stress, performed on a dual-Source CT scanner over a period of 30 s. From the CTP data, time-attenuation curves have been determined both in known ischemic myocardium with a corresponding coronary artery stenosis as proven by a FFR below 0.75 in invasive coronary angiography, as well as in non-ischemic reference myocardium during pharmacological stress. Furthermore, contrast enhancement in the ascending aorta was determined. The time point for an optimal contrast (i.e., difference in Hounsfield Units, HU) between ischemic and normal myocardium was determined. Under pharmacological stress using adenosine, a maximum mean HU difference between ischemic and non-ischemic myocardium (17.7–22.5 HU) was observed 24–32 s after injection of contrast medium. The maximal attenuation difference between normal and ischemic myocardium ranged from 15 to 77 HU in the analyzed patient cohort. When applying a bolus-tracking technique with an automatic contrast detection in the proximal ascending aorta, the optimal time frame for stress CTP was between 8 and 16 s after contrast enhancement in the aorta exceeds 100 HU, or between 7 and 15 s using a threshold of 150 HU. For first-pass CT myocardial perfusion imaging there is a time frame of approximately 8 s for optimal differentiation of ischemic and non-ischemic myocardium, which will be helpful to optimize single-phase CTP scans.     

Multi-modality imaging for the assessment of myocardial perfusion with emphasis on stress perfusion CT and MR imaging

High-quality and non-invasive diagnostic tools for assessing myocardial ischemia are necessary for therapeutic decisions regarding coronary artery disease. Myocardial perfusion has been studied using myocardial contrast echo perfusion, single-photon emission computed tomography, positron emission tomography, cardiovascular magnetic resonance, and, more recently, computed tomography. The addition of coronary computed tomography angiography to myocardial perfusion imaging improves the specificity and overall diagnostic accuracy of detecting the hemodynamic significance of coronary artery stenosis. This study reviews the benefits, limitations, and imaging findings of various imaging modalities for assessing myocardial perfusion, with particular emphasis on stress perfusion computed tomography and cardiovascular magnetic resonance imaging.     

Pharmacologic stress myocardial perfusion imaging

Pharmacologic stress agents (dipyridamole, adenosine and dobutamine) allow virtually all patients to be safely assessed for ischemic heart disease. These agents have mild but significant side effects, mandating a thorough knowledge of indications, contraindications, side effects and management before their use. Adjunctive exercise improves image quality in vasodilator pharmacologic myocardial perfusion imaging. Diabetics, especially women, have a much higher cardiac event rate than nondiabetics for an equal amount of ischemia. They also have a higher incidence of asymptomatic ischemia. There is growing support for screening with myocardial perfusion imaging (MPI) for asymptomatic ischemia in diabetics. The ability of MPI to identify hypocontractile but viable myocardium, thus predicting improvement in myocardial function after revascularization, is one of the most powerful uses of the modality. Vasodilator MPI should be used as the initial test in patients with left bundle branch block or paced ventricular rhythm, even if they are able to exercise.     

Added value of CT myocardial perfusion imaging

Multidetector CT angiography (MDCTA) has become an accurate, noninvasive test for the diagnosis of coronary atherosclerosis. Studies have established a good sensitivity and an excellent negative predictive value for the diagnosis of coronary stenoses of 50% or greater severity. However, MDCTA is more limited in patients with disease with a lower specificity and positive predictive value for predicting atherosclerosis causing myocardial ischemia. Although radionuclide myocardial perfusion imaging (MPI) has been the mainstay for evaluating the presence of myocardial ischemia and scar in patients at risk for coronary artery disease, contrast-enhanced multidetector CT (MDCT) alone, with or without vasodilator stress, has the potential to provide both anatomical and functional information on coronary atherosclerosis and its impact on myocardial perfusion. We review the current status of MDCT MPI, including its advantages, limitations, and pitfalls.     

高血压脑血肿周围组织的CT灌注成像研究

目的应用动态CT灌注成像对急性期及亚急性期高血压脑血肿周围组织灌注情况进行观察,并探讨其转归。方法对15例采用内科保守治疗的高血压脑出血病人进行前瞻性研究,分别于急性期及亚急性期行CT平扫及CT灌注成像扫描。测量血肿周围组织及对侧镜像区脑血流量（CBF）、脑血容量（CBV）、平均通过时间（MTT）及急性期血肿最大层面血肿及周围低灌注区面积,于亚急性期选择与急性期同一层面测量血肿周围强化环所包围的面积。结果灌注参数图示急性期血肿周围组织CBF、CBV均较对侧镜像区降低（Z分别为3.124、3.239,P值均小于0.05）,MTT较对侧延长（Z=2.726,P〈0.05）。亚急性期血肿周围组织CBF亦较对侧降低（Z=3.408,P〈0.05）,与急性期比较无明显变化（Z=1.136,P〉0.05）;血肿周围组织CBV也降低（Z=2.159,P〈0.05）,但是与急性期比较有较明显升高（Z=1.988,P〈0.05）;MTT较对侧延长（Z=3.351,P〈0.05）,与急性期比较无明显差异（Z=1.193,P〉0.05）。急性期血肿最大层面血肿及周围组织之低灌注区面积与亚急性期同一层面血肿周围强化环所包围之面积比较无明显差异（Z=1.590,P〉0.05）。结论高血压脑出血病人血肿周围于急性期存在低灌注状态,而经保守治疗后这种低灌注状态在亚急性期并不会有明显改善,且处于低灌注状态的组织最终很可能会坏死。     

核素心肌灌注显像与多层螺旋CT血管成像对心肌桥的对比分析

目的探讨99 Tcm-MIBI心肌灌注显像对心肌桥的临床价值。方法回顾性分析105例冠状动脉CTA诊断为心肌桥并接受运动及静息99 Tcm-MIBI心肌灌注显像的患者资料,分析心肌灌注显像结果,并与冠状动脉CTA结果进行比较。结果 105例心肌桥患者中,根据Nobel分级法,Ⅰ级狭窄21例,Ⅱ级狭窄24例,Ⅲ级狭窄60例;其中60例出现心肌缺血改变。缺血组与非缺血组心肌桥患者冠状动脉CTA显示狭窄程度的差异有统计学意义(χ2=61.731,P<0.001)。不同部位心肌桥血管支发生异常灌注的差异无统计学意义(χ2=3.588,P=0.166)。结论 99 Tcm-MIBI心肌灌注显像能够用于评价冠状动脉心肌桥。     

CT myocardial perfusion imaging: current status and future perspectives

Computed tomography myocardial perfusion (CTP) combined with coronary computed tomography angiography (CCTA) may constitute a “1-stop shop” for the noninvasive diagnosis of hemodynamically significant coronary stenosis during a single CT examination. CTP shows high diagnostic performance and provides incremental value over CCTA for the detection of hemodynamically significant coronary stenosis in patients with a high Agatston calcium score or coronary artery stents. Future studies should determine the optimal protocol and clinical value of CTP for guiding revascularization strategy and prognostication. In this article, we review the current status and future perspectives of CTP, focusing on technical considerations, clinical applications, and future research topics.     

Adenosine-stress dynamic myocardial perfusion imaging using 128-slice dual-source CT: optimization of the CT protocol to reduce the radiation dose

The aim of this study was to compare the radiation dose and image quality of different adenosine-stress dynamic myocardial perfusion CT protocols using a 128-slice dual-source computed tomography (DSCT) scanner. We included 330 consecutive patients with suspected coronary artery disease. Protocols employed the following dynamic scan parameters: protocol I, a 30-s scan with a fixed tube current (FTC, n = 172); protocol II, a 30-s scan using an automatic tube current modulation (ATCM) technique (n = 108); protocol III, a 14-s scan using an ATCM (n = 50). To determine the scan interval for protocol III, we analyzed time-attenuation curves of 26 patients with myocardial perfusion who had been scanned using protocol I or II. The maximum attenuation difference between normal and abnormal myocardium occurred at 18.0 s to 30.3 s after initiation of contrast injection. Myocardial perfusion images of FTC and ATCM were of diagnostic image quality based on visual analysis. The mean radiation dose associated with protocols I, II, and III was 12.1 ± 1.6 mSv, 7.7 ± 2.5 mSv, and 3.8 ± 1.3 mSv, respectively (p < 0.01). Use of a dose-modulation technique and a 14-s scan duration for adenosine-stress CT enables significant dose reduction while maintaining diagnostic image quality.