Characterization of cerebrovascular responses to hyperoxia and hypercapnia using MRI in rat

Understanding cerebrovascular responses to hyperoxia and hypercapnia is important for investigating exogenous regulation of cerebral hemodynamics. We characterized gas-induced vascular changes in the brains of anesthetized healthy rats using magnetic resonance imaging (MRI) while the rats inhaled 100% O₂ (hyperoxia) and 5% CO₂ (hypercapnia). We used echo planar imaging (EPI), arterial spin labeling (ASL), and intravascular superparamagnetic iron oxide nanoparticles (SPION) to quantify vascular responses as measured by blood oxygenation level dependence (BOLD), cerebral blood flow (CBF), cerebral blood volume (CBV), microvascular volume (MVV), and vessel size index (VSI) in multiple brain regions. Hyperoxia resulted in a statistically significant increase in BOLD-weighted MRI signal and significant decrease in CBF and CBV (P < 0.05). During hypercapnia, we observed significant increases in BOLD signal, CBF, MVV, and CBV (P < 0.05). Despite the regional variability, general trends of vasoconstriction and vasodilation were reflected in VSI changes during O₂ and CO₂ challenges. Interestingly, there was an evident spatial disparity between the O₂ and CO₂ stimuli-induced functional activation maps; that is, cortical and subcortical regions of the brain exhibited notable differences in response to the two gases. Hemodynamic parameters measured in the cortical regions showed greater reactivity to CO₂, whereas these same parameters measured in subcortical regions showed greater responsivity to O₂. Our results demonstrate significant changes of hemodynamic MRI parameters during systemic hypercapnia and hyperoxia in normal cerebral tissue. These gas-dependent changes are spatiotemporally distinctive, suggesting important feasibility for exogenously controlling local cerebral perfusion.     

头颈部CTA联合全脑CT灌注一站式扫描中时间间隔对灌注参数的影响

目的 探讨头颈部CTA联合全脑CT灌注（CTP）一站式扫描中,时间间隔对灌注参数的影响。方法 回顾性分析60例急性脑缺血症状患者的标准脑CTP图像（标准组）,于颅脑CTP图像中将动脉峰值期前后各1组扫描数据剔除,使得其前后间隔时间增加至4.5 s,模拟头颈部CTA联合全脑CTP一站式扫描（模拟组）。计算标准组与模拟组灌注参数[脑血流量（CBF）、脑血容量（CBV）、平均通过时间（MTT）]绝对百分比误差值,并分析脑灰质左侧与右侧、白质左侧与右侧灌注参数比值（rCBF、rCBV、rMTT）的相关性。结果 基底核层面CBF、CBV、MTT的绝对百分比误差值均值均<10%。灰质左侧与右侧rCBF（r=0.988,P<0.001）、rCBV（r=0.963,P<0.001）、rMTT（r=0.983,P<0.001）均呈正相关,白质左侧与右侧rCBF（r=0.980,P<0.001）、rCBV（r=0.957,P<0.001）、rMTT（r=0.986,P<0.001）均呈正相关。结论 头颈部CTA联合全脑CTP一站式扫描中时间间隔对灌注参数的影响较小。     

Three-dimensional cerebral vasculature of the CBA mouse brain: a magnetic resonance imaging and micro computed tomography study

Studies of mouse cerebral vasculature to date have focused on the circle of Willis without examining the morphological distribution of blood vessels through the rest of the brain. Since mouse models are frequently used in brain-related studies, there is a need for a comprehensive cerebral vasculature atlas for the mouse with an emphasis on the location of vessels with respect to neuroanatomical structures, the watershed regions associated with specific arteries, as well as a consistent nomenclature of the cerebral vessels. This article describes such an atlas, based on a combination of magnetic resonance and computed tomography technology to yield high-resolution volumetric and vasculature data on CBA mouse. This three-dimensional vasculature dataset provides an anatomical resource for future mouse studies.     

一站式CT评价烟雾病及烟雾综合征患者出现常春藤征与脑血流动力学及侧支循环的关系

目的 以一站式CT血管造影(CTA)-CT灌注(CTP)观察烟雾病(MMD)/烟雾综合征(MS)常春藤征与脑血流动力学及侧支循环的关系。方法 纳入43例MMD/MS患者,基于MR液体衰减反转恢复序列判断常春藤征,记录存在缺血灶/出血灶脑区(阳性区域);于CTP参数图测量688个脑区的脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)、达峰时间(TTP)及延迟时间(DLY)。以CTA评估侧支循环评分,观察常春藤征(IS)与侧支循环的关系。结果 688个脑区中,166个(166/688,24.13%)可见(IS组)、522个(522/688,75.87%)未见常春藤征(NIS组);较常见IS脑区依次为基底节区、半卵圆中心层面大脑中动脉供血区及半卵圆中心层面大脑前动脉供血区。IS组内阳性区域占比高于NIS组(17.47%vs. 8.05%,P=0.001)。相比NIS组,IS组CBV增加,MTT、TTP及DLY均延长(P均<0.001)而侧支循环分级较低(P=0.006)。结论 MMD/MS患者出现常春藤征提示存在更严重脑灌注损害及侧支循环不良,具有潜在脑缺血/出血风险。     

Investigation of neural progenitor cell induced angiogenesis after embolic stroke in rat using MRI

Using MRI, we investigated dynamic changes of brain angiogenesis after neural progenitor cell transplantation in the living adult rat subjected to embolic stroke. Neural progenitor cells isolated from the subventricular zone (SVZ) of the adult rat were labeled by superparamagnetic particles and intracisternally transplanted into the adult rat 48 h after stroke (n = 8). Before and after the transplantation, an array of MRI parameters were measured, including high resolution 3D MRI and quantitative T1, T1sat (T1 in the presence of an off-resonance irradiation of the macromolecules of brain), T2, the inverse of the apparent forward transfer rate for magnetization transfer (kinv), cerebral blood flow (CBF), cerebral blood volume (CBV), and blood-to-brain transfer constant (Ki) of Gd-DTPA. The von Willerbrand factor (vWF) immunoreactive images of coronal sections obtained at 6 weeks after cell transplantation were used to analyze vWF immunoreactive vessels. MRI measurements revealed that grafted neural progenitor cells selectively migrated towards the ischemic boundary regions. In the ischemic boundary regions, angiogenesis confirmed by an increase in vascular density and the appearance of large thin wall mother vessels was coincident with increases of CBF and CBV (CBF, P < 0.01; CBV, P < 0.01) at 6 weeks after treatment, and coincident with transient increases of K(i) with a peak at 2 to 3 weeks after cell therapy. Relative T1, T1sat, T2, and kinv decreased in the ischemic boundary regions with angiogenesis compared to that in the non-angiogenic ischemic region (T1, P < 0.01 at 6 weeks; T1sat, P < 0.05 at 2 to 6 weeks; T2, P < 0.05 at 3 to 6 weeks; kinvP < 0.05 at 6 weeks). Of these methods, Ki appear to be the most useful MR measurements which identify and predict the location and area of angiogenesis. CBF, CBV, T1sat, T1, T2, and kinv provide complementary information to characterize ischemic tissue with and without angiogenesis. Our data suggest that select MRI parameters can identify the cerebral tissue destined to undergo angiogenesis after treatment of embolic stroke with cell therapy.     

Functional micro-ultrasound imaging of rodent cerebral hemodynamics

Healthy cerebral microcirculation is crucial to neuronal functioning. We present a new method to investigate microvascular hemodynamics in living rodent brain through a focal cranial window based on high-frequency ultrasound imaging. The method has a temporal resolution of 40ms, and a 100μm in-plane and 600μm through-plane spatial resolution. We use a commercially available high-frequency ultrasound imaging system to quantify changes in the relative cerebral blood volume (CBV) by measuring the scattered signal intensity from an ultrasound contrast agent circulating in the vasculature. Generalized linear model analysis is then used to produce effect size and significance maps of changes in cerebral blood volume upon electrical stimulation of the forepaw. We observe larger CBV increases in the forelimb representation of the primary somatosensory cortex than in the deep gray matter with stimuli as short as 2s (5.1 ± 1.3% vs. 3.3 ± 0.6%). We also investigate the temporal evolution of the blood volume changes in cortical and subcortical gray matter, pial vessels and subcortical major vessels, and show shorter response onset times in the parenchymal regions than in the neighboring large vessels (1.6 ± 1.0s vs. 2.6 ± 1.3s in the cortex for a 10 second stimulus protocol). This method, which we termed functional micro-ultrasound imaging or fMUS, is a novel, highly accessible, and cost-effective way of imaging rodent brain microvascular topology and hemodynamics in vivo at 100micron resolution over a 1-by-1cm field of view with 10s-100s frames per second that opens up a new set of questions regarding brain function in preclinical models of health and disease.     

症状性单侧颈内动脉颅内段严重狭窄或闭塞全脑CT灌注成像表现模式

目的:研究症状性单侧颈内动脉(ICA)严重狭窄或闭塞的320排CT全脑灌注成像(CTPI)表现及血流动力学模式。资料与方法:回顾分析23例症状性单侧ICA严重狭窄(>70%)或闭塞的患者的全脑CTPI资料,分别重建4D-CTA及CTPI参数图(脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)、达峰时间(TTP)及延迟(Delay)图),分别记录ICA狭窄程度、患者临床症状、有无梗死及梗死部位、CTPI参数图特点及绝对值,并对病灶侧及对侧脑区灌注参数值进行比较。结果:单侧ICA闭塞15例,严重狭窄8例。大脑中动脉(MCA)和/或大脑前动脉(ACA)分布区脑梗死13例,内侧分水岭区梗死6例,基底节区腔隙性脑梗死2例,无梗死2例。CTPI血流动力学模式有:①CBV/CBF基本正常,MTT/TTP/Delay延长(4例);②CBV基本正常,CBF轻度下降,MTT/TTP/Delay延长(3例);③CBV/CBF明显减低,MTT局灶缩短并周围MTT/TTP/Delay延长(16例)。统计学分析显示:病灶同侧CBV、CBF、TTP、Delay与对侧比较差异有统计学意义(P<0.05);病灶同侧MTT与对侧比较差异无统计学意义(P=0.66)。结论:320排CT全脑容积CTA/CTPI能一次显示颅内段ICA的狭窄程度并能全面反映脑血流动力学变化,为临床治疗提供重要信息。     

急性脑梗死治疗前后脑血流动力学改变:CT灌注成像

目的观测急性脑梗死治疗前后多层螺旋CT灌注成像(MSCTPI)的脑血流动力学指标变化.方法31例发病6～22 h的临床诊断为急性脑梗死的患者,分别于发病第1天,第7～21天行常规CT平扫及MSCTPI检查.结果治疗后病变区血流量、血容量较治疗前均增加(t=4.57,P＜0.01;t=3.81,P＜0.01);达峰时间较治疗前缩短(t=3.62,P＜0.01).结论急性脑梗死治疗前后CT灌注成像的脑血流动力学指标变化明显,提示早期干预具有治疗效果.     

Evaluation of fetal regional cerebral blood perfusion using power Doppler ultrasound and the estimation of fractional moving blood volume.

OBJECTIVE: To standardize the evaluation of regional fetal brain blood perfusion, using power Doppler ultrasound (PDU) to estimate the fractional moving blood volume (FMBV) and to evaluate the reproducibility of this estimation. METHODS: Brain blood perfusion was evaluated in 35 normally grown fetuses at 28-30 weeks of gestation, using PDU. The following cerebral regions were included in the PDU color box: anterior sagittal, complete sagittal, basal ganglia, and cerebellar. Ten consecutive good-quality images of each anatomical plane were recorded and the delimitation of the region of interest (ROI) was performed off-line. FMBV was quantified in the ROI of all images and the mean considered as the final value. Differences between regions, variability, reproducibility and agreement between observers were assessed. RESULTS: Power Doppler images of the described anatomical planes were obtained in all cases, regardless of fetal position. The median time for the acquisition of the images was 7 (range 4-12) min. Mean (range) FMBV values were: anterior sagittal, 16.5 (10.7-22.8)%, inter-patient coefficient of variation (CV) 0.22; complete sagittal, 13.5 (8.8-16.1)%, CV 0.27; basal ganglia, 18.3 (10.7-27.6)%, CV 0.27; and cerebellar, 6.6 (3.0-11.0)%, CV 0.38. There were statistically significant differences in FMBV between cerebellar and complete sagittal ROIs with the frontal and basal ganglia regions. Reproducibility analyses showed an intraclass correlation coefficient of 0.91 (95% CI 0.67-0.97) and an interclass correlation coefficient of 0.87 (95% CI 0.70-0.94). Interobserver agreement showed a mean difference between observers of -0.2 (SD 2.7) with 95% limits of agreement -5.6 to 5.2. CONCLUSIONS: When the regions of interest are well defined, the FMBV estimate offers a method to quantify blood flow perfusion in different fetal cerebral areas. There appear to be regional differences in FMBV within the fetal brain.     

多层螺旋CT灌注成像诊断脑肿瘤

目的探讨多层螺旋CT(MSCT)灌注成像在脑肿瘤诊断中的临床应用价值.方法 34例脑肿瘤行MSCT灌注成像扫描,其中脑胶质瘤10例,脑转移瘤9例,脑膜瘤7例,垂体瘤5例,脑胶质瘤复发3例.以3.5 ml/s速率静脉团注非离子对比剂50 ml,采用CT电影扫描技术对肿瘤中心层面进行四层同层灌注扫描,层厚10 mm/2i,扫描延迟时间5 s,数据采集45 s.应用Perfusion 软件进行灌注成像分析.结果脑肿瘤的血流量(CBF)值均显著增加,胶质瘤≈脑膜瘤＞转移瘤＞垂体瘤;脑血容量(CBV)值稍有增加,胶质瘤≈脑膜瘤＞转移瘤(垂体瘤无增加);平均通过时间(MTT)在转移瘤有明显延长;脑表面通透性(PS)值均显著增加,垂体瘤＞脑膜瘤＞胶质瘤≈转移瘤.复发胶质瘤的CBF值达110 ml/(100 g*min); PS图有助于肿瘤范围的准确界定和发现小病灶.结论 MSCT灌注成像在显示脑肿瘤血流灌注的特点、在脑肿瘤的鉴别诊断、肿瘤范围的界定以及在肿瘤术后复发诊断中均具有一定的临床应用价值.     

全脑CTP定量分析颅内动脉粥样硬化性狭窄患者血管表面渗透性

目的 采用计算机断层扫描灌注成像（CTP）观察颅内动脉粥样硬化性狭窄（ICAS）患者脑组织血管表面渗透性（PS）和血流动力学状态及治疗后改变。方法 对59例ICAS患者（ICAS组）及16名志愿者（对照组）行全脑CTP，并对ICAS组17例行责任血管支架植入术。采用定量分析软件测量责任动脉供血区血管PS、血流动力学参数[脑血流量（CBF）、血容量（CBV）及平均通过时间（MTT）]，并获得健侧镜像值，比较2组血管PS及血流动力学参数的差异，对比ICAS组支架植入前后血管PS及血流动力学参数变化，分析血管PS与血流动力学参数的相关性。结果 相比对照组，ICAS组患侧血管PS值增高、CBF减低、MTT延长（t=7.77、-4.84、7.47，P均<0.05）。相比健侧，ICAS组患侧血管PS值增高、CBF减低、CBV增加、MTT延长（t=-4.38、-4.48、4.49、8.35，P均<0.05）；植入支架后患侧血管PS值、CBF、MTT与术前差异均有统计学意义（t=0.95、-4.05、3.50，P均<0.05）。血管PS与MTT、CBV分别呈高度、中度正相关（r=0.86、0.59，P均<0.05），与CBF呈低度负相关（r=-0.31，P<0.05）。结论 血管PS可作为定量评价ICAS治疗效果的影像学标志物。ICAS患者患侧脑组织血管PS明显增加，植入支架后较术前明显降低。PS结合血流动力学参数能更准确地反映脑组织病理生理改变，为个性化治疗ICAS及评估疗效提供参考。     

Regional distribution of human cerebral vascular mean transit time measured by positron emission tomography

Cerebral vascular mean transit time (MTT) characterizes the cerebral circulation. MTT has been measured in humans by carotid angiography, x-ray computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). However, regional distribution of MTT has not been investigated in detail. Thus, we investigated regional distribution of normal human MTT. Regional cerebral blood flow (CBF) and cerebral blood volume (CBV) were measured by PET with H(2)(15)O and (11)CO, respectively, in each of 10 normal subjects. MTT was calculated as MTT = CBV/CBF. MTT for cerebral cortical regions was 3.2 to 4.4 s. These values were in accord with MTT measured by carotid angiography, CT, and MRI. Considered regionally, MTT was longest in the temporooccipital cortex, and shorter in the cerebellum, thalamus, and putamen, than in all other regions. These regional differences in MTT that are inversely proportional to cerebral perfusion pressure might relate to regional differences in cerebral vascular tone. Simulation studies showed that errors in CBF and thus MTT caused by regional differences in regional tracer appearance time, distribution volume, and gray-white matter mixing were negligible.     

Arterial spin-labeled MRI study of migraine attacks treated with rizatriptan

Spin-tag perfusion imaging is an MRI method that quantitatively measures cerebral blood flow. Compared with conventional perfusion techniques, advantages of this arterial spin-labeling (ASL) include repeatability and the avoidance of intravenous contrast administration. In the present study, we performed an analysis of 3T high-field MRI examinations utilizing ASL perfusion during migraine attacks. A 32-year-old male patient was studied in three situations: during migraine attack within 1 h post-onset, 30 min after oral administration of rizatriptan 10 mg, and attack-free period. Normalized ASL images acquired during migraine attack showed significant relative hypoperfusion in the bilateral median thalamic areas including hypothalamus and significant relative hyperperfusion in the frontal cortex compared to images acquired during the migraine-free state. When normalized ASL images acquired 30 min after treatment were compared with those acquired during the attack, relative improvement of perfusion in the bilateral median thalamic areas including hypothalamus was observed. Hypothalamus and its surrounding areas may participate in the pathogenesis in migraine attack.     

低剂量CT血流灌注成像诊断老年痴呆症

目的探讨低剂量CT血流灌注成像(CTPI)在评估老年痴呆症病情与鉴别诊断中的应用价值。方法根据临床诊断标准入组95例老年痴呆症患者(痴呆组),其中52例阿尔茨海默病,43例血管性痴呆;另选30名健康志愿者为对照组。采用多排螺旋CT进行头颅平扫后再进行低剂量CTPI,灌注参数包括脑血容量(CBV)、脑血流量(CBF)、平均通过时间(MTT)和达峰时间(TTP)。选择双侧额叶、颞叶皮质和双侧海马、基底核区域进行测量,运用ROC曲线进行效能评价。结果痴呆组双侧额叶、颞叶皮质、海马和基底核的CBV、CBF值明显高于对照组,其MTT和TTP明显大于对照组(P均<0.05)。根据灌注参数左颞叶MTT、左基底核MTT、左海马MTT诊断老年痴呆的ROC曲线下面积分别为0.959、0.920、0.916,诊断价值较高,左额叶MTT、左基底核CBV曲线下面积为0.867和0.819,诊断价值中等。结论 CTPI诊断老年痴呆症有一定意义,可作为一种有效的临床诊断方法。     

A time-invariant visco-elastic windkessel model relating blood flow and blood volume

The difference between the rate of change of cerebral blood volume (CBV) and cerebral blood flow (CBF) following stimulation is thought to be due to circumferential stress relaxation in veins (Mandeville, J.B., Marota, J.J.A., Ayata, C., Zaharchuk, G., Moskowitz, M.A., Rosen, B.R., Weisskoff, R.M., 1999. Evidence of a cerebrovascular postarteriole windkessel with delayed compliance. J. Cereb. Blood Flow Metab. 19, 679–689). In this paper we explore the visco-elastic properties of blood vessels, and present a dynamic model relating changes in CBF to changes in CBV. We refer to this model as the visco-elastic windkessel (VW) model. A novel feature of this model is that the parameter characterising the pressure–volume relationship of blood vessels is treated as a state variable dependent on the rate of change of CBV, producing hysteresis in the pressure–volume space during vessel dilation and contraction. The VW model is nonlinear time-invariant, and is able to predict the observed differences between the time series of CBV and that of CBF measurements following changes in neural activity. Like the windkessel model derived by Mandeville, J.B., Marota, J.J.A., Ayata, C., Zaharchuk, G., Moskowitz, M.A., Rosen, B.R., Weisskoff, R.M., 1999. Evidence of a cerebrovascular postarteriole windkessel with delayed compliance. J. Cereb. Blood Flow Metab. 19, 679–689, the VW model is primarily a model of haemodynamic changes in the venous compartment. The VW model is demonstrated to have the following characteristics typical of visco-elastic materials: (1) hysteresis, (2) creep, and (3) stress relaxation, hence it provides a unified model of the visco-elastic properties of the vasculature. The model will not only contribute to the interpretation of the Blood Oxygen Level Dependent (BOLD) signals from functional Magnetic Resonance Imaging (fMRI) experiments, but also find applications in the study and modelling of the brain vasculature and the haemodynamics of circulatory and cardiovascular systems.     

DSC-MRI鉴别诊断胶质母细胞瘤、单发脑转移瘤及脑淋巴瘤

目的 探讨动态磁敏感对比增强磁共振成像（DSC-MRI）鉴别诊断胶质母细胞瘤、单发脑转移瘤及脑淋巴瘤的价值。方法 回顾性分析经活检或术后病理证实的胶质母细胞瘤患者17例、单发脑转移瘤患者15例、淋巴瘤患者17例。患者术前均接受MRI常规平扫、增强及DSC-MRI扫描,获得脑血容量（CBV）伪彩图及时间-信号强度曲线,分别测量瘤体、瘤周水肿区及对侧正常白质区的CBV值,计算相对脑血容量（rCBV）值和瘤体的信号强度恢复百分比（PSR）。应用ROC曲线分析各指标对3种肿瘤的诊断效能。结果 胶质母细胞瘤、单发脑转移瘤及脑淋巴瘤均表现为肿瘤实性区域明显强化伴瘤周水肿。瘤体rCBV除胶质母细胞瘤与单发脑转移瘤无差异外,余两两比较差异均有统计学意义（P均<0.05）;瘤周rCBV除单发脑转移瘤与淋巴瘤无差异外,余两两比较差异均有统计学意义（P均<0.05）;瘤体PSR值除胶质母细胞瘤与单发脑转移瘤无差异外,余两两比较差异均有统计学意义（P均<0.05）。ROC曲线示瘤体PSR为鉴别淋巴瘤及非淋巴瘤的最佳指标,敏感度、特异度分别为100%和81.3%;瘤周rCBV为鉴别胶质母细胞瘤及单发脑转移瘤的最佳指标,敏感度、特异度分别为94.1%和86.7%。结论 rCBV和PSR结合可提高鉴别诊断3种脑肿瘤的效能。     

320排CT灌注成像时间间隔增加对缺血性脑卒中患者放射剂量的影响

目的 研究增加急性缺血性脑卒中患者320排灌注CT(PCT)扫描时间间隔对放射剂量及灌注参数值的影响.方法 回顾性分析23例急性缺血性脑卒中患者的PCT资料,在后处理工作站上分别采用2种不同数据重建方法:①全部数据法:选用全部预设的20个容积数据单元重建;②间隔数据法:间隔选取一个容积数据单元,共10个.分别测量梗死区及对侧镜像区灌注参数图(C BV、CBF、MTT)兴趣区绝对值及同层梗死面积范围,并计算二种数据重建方法产生的有效放射剂量值.比较二种重建方法测量的主要灌注参数值和梗死面积的差异、相关性及放射剂量.结果 两种方法计算的CBV、CBF、MTT差异无统计学意义(P＞0.05);两种方法测量CBV、CBF、MTT相关性有统计学意义(P=0.01,r=0.55).全部数据法、间隔数据法产生有效放射剂量分别为12.04mSV和6.24mSV,后者相当于前者的52％.结论 增加320排PCT成像时间间隔对灌注参数值及梗死面积无显著性影响,并且可以明显减少放射剂量.     

二次灌注对全定量脑磁共振灌注成像血流动力学影响的初步研究

目的探索二次灌注对全定量脑磁共振灌注成像血流动力学的影响,并得出全定量脑磁共振灌注成像(self-calibrated EPI perfusion-weighted imaging,Scale-PWI)的最佳注药时期。材料与方法 100名无脑血管疾病的志愿者按注药时期(3、5、7、9、11期)不同分为5组,采取MR常规扫描及全定量灌注扫描,自动得出脑血流量(cerebral blood flow,CBF)、脑血容量(cerebral blood volume,CBV),再通过常规灌注加权成像(perfusion weighted imaging,PWI),后处理方法得出灌注时间-信号强度图,分析其是否存在二次灌注。测量受试者各感兴趣区(额叶白质、丘脑及小脑)的CBF、CBV的数值。结果第3期、第5期注射药物行全定量灌注扫描的患者存在二次灌注的概率分别为95%、80%;第7期、第9期注药存在二次灌注的概率分别为10%、5%;第11期注药存在二次灌注的概率为0%,但是注药时机过晚,灌注成功率较低,数据无统计学意义。其次,不同注射时期组内两侧额叶白质、丘脑及小脑的CBF、CBV左右对比,无明显统计学差异(P0.05);测量不同注射时期的额叶白质、丘脑及小脑的CBV、CBF值,将其中存在明显二次灌注的CBV、CBF值与不存在明显二次灌注的CBV、CBF值进行比较,存在二次灌注的CBV、CBF值明显偏大。结论全定量脑磁共振灌注成像的最佳注药时期为第7~9期;存在明显二次灌注的CBV、CBF值会偏大。     

动态对比增强磁共振成像观察复发缓解型多发性硬化微循环改变

目的 应用动态对比增强磁共振成像（DCE-MRI）分析复发缓解型多发性硬化（RRMS）病灶的渗透、灌注及直方图参数及其与临床评分的相关性。方法 对27例RRMS患者行常规MRI和DCE-MRI检查并应用Tofts模型进行后处理,定量分析MS患者病灶及看似正常白质（NAWM）的容积转移常数K^trans、脑血流量（CBF）和脑血容量（CBV）,并与临床扩展残疾状态量表（EDSS）评分及病程进行相关性分析。结果 ①强化病灶的K^trans值明显高于非强化病灶、病灶旁NAWM及远离病灶NAWM（χ²=24.771,P<0.001）;非强化病灶的K^trans值明显高于病灶旁NAWM与远离病灶NAWM（P均<0.05）。②强化病灶的CBF、CBV明显高于非强化病灶及NAWM,但非强化病灶的CBF、CBV与病灶旁、远离病灶NAWM的差异均无统计学意义（P均>0.05）。③直方图结果显示非强化病灶的偏度值与强化病灶的差异无统计学意义,但后者分布更接近于正态分布;两者的峰度值均低于正态分布的峰值。④K^trans、CBF、CBV与EDSS评分及病程均无相关性（P>均0.05）。结论 DCE-MRI结合Tofts模型可显示MS病灶及NAWM的微血管渗透及灌注异常,直方图可能对MS不同病灶类型的鉴别具有一定的帮助。     

CT灌注成像对急性缺血性脑卒中患者脑组织血流灌注情况、脑侧支血流循环状态及责任血管狭窄的评估价值

目的  探究CT灌注成像(CTPI)对急性缺血性脑卒中患者脑组织血流灌注情况、脑侧支血流循环状态及责任血管狭窄的评估价值。 方法  选取攀枝花市中西医结合医院2021年3月~2022年3月收治的51例急性缺血性脑卒中患者,入院后行CT平扫及CT灌注成像。分析患者不同区域脑血流量(CBF)、脑血容量(CBV)、对比剂平均通过时间(MTT)、对比剂峰值时间(TTP),比较不同侧支血流循环状态CTPI参数情况及责任血管不同狭窄程度。 结果  CTPI显示,46例脑组织血流灌注发生异常,CTPI阳性率为90.20%(46/51)。患者患侧梗死病灶区及缺血半暗带CBF值、CBV值均小于健侧,MTT值、TTP值均长于健侧(P < 0.05)。侧支循环良好者患侧CBF值小于健侧,MTT值及TTP值均长于健侧(P < 0.05),而患侧与健侧CBV值比较差异无统计学意义(P > 0.05);侧支循环不良者患侧CBF值及CBV值均小于健侧,且MTT值及TTP值均长于健侧(P < 0.05)。CTPI提示AIS脑组织血流灌注异常患者责任血管重度狭窄或闭塞发生率高于CTPI提示血流灌注正常患者(P < 0.05)。 结论  CTPI可及时准确反映急性缺血性脑卒中患者梗死病灶区、缺血半暗带血流灌注情况,有助于临床掌握患者侧支循环状态,对责任血管狭窄程度进行客观评估。