Vascular Wall Imaging of Unruptured Cerebral Aneurysms with a Hybrid of Opposite-Contrast MR Angiography

BACKGROUND AND PURPOSE:Inflammation and degeneration of the intracranial saccular aneurysm wall play a major role in aneurysm formation, development and subsequent rupture. The aim of this study was to characterize the walls of unruptured intracranial aneurysms by using a hybrid of opposite-contrast MRA at 3T.MATERIALS AND METHODS:Fourteen consecutive patients with 17 unruptured intracranial aneurysms who initially underwent clipping surgery were prospectively evaluated. All aneurysms were scanned preoperatively by using a hybrid of opposite-contrast MRA in 3T high-resolution MR imaging. We classified intraoperative findings of atherosclerotic plaques in the aneurysms into 3 grades: grade A (major plaques), grade B (minor plaques), and grade C (no plaques). The contrast ratio of the high-intensity area was also measured relative to the background low-intensity area inside the carotid artery.RESULTS:Findings from preoperative plaque imaging of the aneurysm corresponded to the intraoperative findings in 15 of 16 aneurysms (excluding 1 that was impossible to visualize in its entirety due to anatomic reasons). Overall sensitivity and specificity of the hybrid of opposite-contrast MRA were 88.9% and 100%, respectively. During the operation, 4 aneurysms were classified as grade A; 5, as grade B; and 7, as grade C. The means of the contrast ratio for grades A, B, and C were 0.72 ± 0.03, 0.34 ± 0.30, and −0.02 ± 0.09, respectively.CONCLUSIONS:The hybrid of opposite-contrast MRA can detect visible atherosclerotic plaques in the unruptured aneurysm wall, and the contrast ratio in intracranial aneurysms correlated with their presence and extent. A study including a larger series is needed to validate the diagnostic potential of this imaging technique.

Intracranial aneurysms are common vascular lesions, often consisting of a saccular dilation of a cerebral artery vessel. The prevalence of intracranial aneurysms in the general population is estimated between 2.5% and 5%.^1,2 Aneurysmal rupture occurs with a 1% risk per year, depending on the size, location, and morphometry of the aneurysm, and leads to subarachnoid hemorrhage with associated high morbidity and mortality rates.^1,2 Intracranial aneurysms with an estimated high risk of rupture undergo management via a surgical or endovascular approach, depending on the specific risks of treatment.^3,4 Therefore, it is important to accurately assess the risk of aneurysmal rupture.The pathogenesis of intracranial aneurysms and their natural history are not well-understood. Histopathologic studies have shown that the infiltration of inflammatory cells and the degeneration of the aneurysm wall with atherosclerosis correlates with the formation, development, and rupture risk of cerebral aneurysms.^5–9 However, characterization of the aneurysm wall is limited by imaging data quality and the need to harvest surgical specimens.In this regard, the characteristics of high-field-strength MR imaging, which has a favorable SNR and changes in relaxation time and susceptibility, can depict the intracranial vessel walls and their pathologies, including small vessels with atherosclerosis.^10,11The hybrid of opposite-contrast MR angiography (HOP-MRA) used in this study is a modern technique that combines the advantages of 3D TOF MRA and flow-sensitive black-blood (FSBB) MRA.¹² The clinical efficacy of this technique was established to improve the visualization of peripheral vessels.^13,14 Theoretically, tissue with shorter T1 and T2* introduces high signal in FSBB of HOP-MRA, which demonstrates atherosclerotic plaques, including fat, as high-signal-intensity areas and demonstrates the blood space as low-signal-intensity areas in intracranial aneurysms.¹² The strength of this technique is the dual-echo 3D gradient-echo sequence, which enables a shorter imaging time and minimization of misregistration. The present study investigated the utility of HOP-MRA at 3T for the characterization of visible atherosclerotic plaques in intracranial aneurysms by using subtraction between TOF and FSBB imaging.     

颅内巨大动脉瘤的MRI影像学分析

目的：评价MRI对颅内巨大动脉瘤的诊断价值。方法：搜集经血管造影或手术证实的21例颅内巨大动脉瘤,MR扫描使用3.0TMR系统,FSE和SE脉冲序列。结果：动脉瘤大小为2.5～8.1cm,位于鞍旁10例、鞍上4例、侧裂池3例、后颅窝3例、额顶部1例。载瘤动脉来源于颈内动脉11例、大脑前动脉A1与A2段交界处3例、大脑中动脉M1与M2交界处3例、椎基底动脉3例、大脑前动脉A3段1例。11例伴不同程度的血栓表现为瘤体周边不均匀混杂信号。MRI对伴有血栓形成的动脉瘤实际瘤体大小的显示均优于MRA和DSA。结论：MRI在颅内巨大动脉瘤诊断中对瘤体大小、瘤体内部有无血栓形成及瘤体周围的改变明显优于MRA和DSA。临床疑似颅内动脉瘤时不应只进行MRA或DSA检查。     

脑曼氏裂头蚴病的MRI特征

目的 分析脑曼氏裂头蚴病的MRI表现,以提高对脑曼氏裂头蚴病的MRI诊断水平.方法 回顾分析6例经手术病理确诊的脑曼氏裂头蚴的MRI表现,包括病灶分布、数目、形态、大小、信号及强化情况.结果 6例脑曼氏裂头蚴的常规MRI表现:6例均单发病灶,病灶位置表浅,2例位于顶叶,2例位于额叶,1例位于颞叶,1例位于脑干后部;T1WI呈不均匀低信号,T2WI呈不均匀高信号,周边伴片状水肿;强化后表现为绳结状、小环状、串珠状、结节状及匐行管状强化.结论 脑曼氏裂头蚴的MRI表现具有一定特征性,结合病史和MR随访复查有助于做出准确诊断.     

动态及延时增强磁共振成像对肝血管瘤诊断的评价

目的:研究动态增强及延迟增强扫描磁共振成像对肝血管瘤的诊断价值。材料和方法:34例肝血管瘤病人行常规MRT1WI、T2WI横断面扫描。经肘静脉手推团注0.1mmol/kg体重Gd-DTPA后,再推入10ml生理盐水冲洗后(推入时间5~6s)行射频毁坏傅立叶采集稳态技术T1WI动态增强扫描及延迟增强扫描,分析病灶及邻近肝实质增强。结果:共发现肝血管瘤病灶67个。动态增强见46个病灶呈边缘不连续样的结节样强化,21个病灶呈周边不规则强化或迅速强化充填;5个病灶动态增强早期见引流静脉强化,14个瘤周肝实质强化。延迟增强扫描见53个病灶完全充填强化,14个病灶显示斑片状或裂隙状的低信号未充填区。结论:在磁共振成像检查中,动态增强扫描能够显示肝血管瘤及邻近实质强化方式,延迟增强显示病灶的充填程度,两者结合更有利于肝血管瘤的诊断。     

PC机辅助MR脑灌注成像初步研究

目的:研究PC机辅助MR脑灌注成像软件,探讨其临床应用价值。方法:在PC机上使用MR脑灌注成像软件,对5例健康人和18例脑缺血患者的灌注图像进行后处理,计算出有关脑灌注参数图,包括相对脑血流量(rrCBF)图、相对脑血容量(rrCBV)图、局部灌注达峰时间(TTP)图和团注平均通过时间(bMTT)图。结果:应用MR脑灌注成像软件可以在PC机上实现灌注图像的后处理,脑灌注参数图能够为脑缺血患者提供有价值的脑血液动力学信息,显示灌注异常的范围。结论:PC机辅助MR脑灌注成像软件简单易行,可显示常规MR无法显示的血流动力学异常,对临床和科研具有重要价值。     

CSF Flow Quantification of the Cerebral Aqueduct in Normal Volunteers Using Phase Contrast Cine MR Imaging

Objective

To evaluate whether the results of cerebrospinal fluid (CSF) flow quantification differ according to the anatomical location of the cerebral aqueduct that is used and the background baseline region that is selected.

Materials and Methods

The CSF hydrodynamics of eleven healthy volunteers (mean age = 29.6 years) were investigated on a 1.5T MRI system. Velocity maps were acquired perpendicular to the cerebral aqueduct at three different anatomical levels: the inlet, ampulla and pars posterior. The pulse sequence was a prospectively triggered cardiac-gated flow compensated gradient-echo technique. Region-of-interest (ROI) analysis was performed for the CSF hydrodynamics, including the peak systolic velocity and mean flow on the phase images. The selection of the background baseline regions was done based on measurements made in two different areas, namely the anterior midbrain and temporal lobe, for 10 subjects.

Results

The mean peak systolic velocities showed a tendency to increase from the superior to the inferior aqueduct, irrespective of the background baseline region, with the range being from 3.30 cm/sec to 4.08 cm/sec. However, these differences were not statistically significant. In the case of the mean flow, the highest mean value was observed at the mid-portion of the ampulla (0.03 cm³/sec) in conjunction with the baseline ROI at the anterior midbrain. However, no other differences were observed among the mean flows according to the location of the cerebral aqueduct or the baseline ROI.

Conclusion

We obtained a set of reference data of the CSF peak velocity and mean flow through the cerebral aqueduct in young healthy volunteers. Although the peak systolic velocity and mean flow of the CSF differed somewhat according to the level of the cerebral aqueduct at which the measurement was made, this difference was not statistically significant.     

磁共振DWI、PWI和MRS量化评定超早期脑梗死缺血半暗带

目的:应用扩散加权成像(DWI)、灌注成像(PWI)以及磁共振波谱(MRS)技术界定超早期脑梗死缺血半暗带,力求提出量化评定标准。方法:13例发病时间在2～6h的超急性脑梗死患者行MRI检查,包括DWI、PWI及1HMRS技术,并在2～28d复查T2WI确定最终梗死范围。对梗死中心区、缺血半暗带及对侧镜像区,测量其扩散变化,血流灌注以及代谢改变。结果:①梗死中心区与缺血半暗带表观弥散系数(ADC)平均值分别为7.01×10-4mm2/s及9.36×10-4mm2/s,rADC平均值分别为0.63及0.87,梗死中心区ADC及rADC均明显降低,缺血半暗带ADC及rADC轻度下降,二者之间差异有显著性意义。②PWI显示11例超急性脑梗死存在灌注缺损区或灌注减低区,2例腔隙性脑梗死未见明显灌注异常。③MRS改变为乳酸(Lac)浓度升高和N乙酰天门冬氨酸盐(NAA)水平降低。④对于PWI>DWI者,ADC值轻度降低(<22%)Lac升高且NAA正常或轻度下降(<14%)的区域可能为缺血半暗带;而ADC值明显降低(25%～53%)Lac升高且NAA明显下降的区域(16%～34%)可能为不可逆损伤区。结论:综合应用DWI、PWI和MRS可发现超早期脑梗死,并预测缺血半暗带。     

Development of the Fetal Cerebral Cortex in the Second Trimester: Assessment with 7T Postmortem MR Imaging

BACKGROUND AND PURPOSE:Few investigators have analyzed the fetal cerebral cortex with MR imaging of high magnetic strength. Our purpose was to document the sulcal development and obtain quantitative measurements of the fetal brain in the second trimester.MATERIALS AND METHODS:The brains of 69 fetal specimens, with GA 12–22 weeks, were first scanned on a 7T MR imaging scanner. Then the sequential development of the different fissures and sulci was analyzed, and quantitative measurements of the cerebral cortex were obtained.RESULTS:A new chronology of sulcal development during 12–22 weeks GA was summarized. Before 12 weeks, few sulci were present; by 16 weeks, many sulci were present. The 16th week could be considered the most intensive time point for sulcal emergence. Most sulci, except for the postcentral sulcus and intraparietal sulcus, were present by 22 weeks GA. Measurements of the fetal brains, each with different growth rates, linearly increased with GA, but no sexual dimorphisms or cerebral asymmetries were detected.CONCLUSIONS:The second trimester is the most important phase, during which most sulci are present and can be clearly shown on 7T postmortem MR imaging. It is apparent that the specific time during which neuropathologic features of sulci appear, previously thought to be well understood, should be redefined. Quantitative data provide assistance in the precise understanding of the immature brain. The present results are valuable in anatomic education, research, and assessment of normal brain development in the uterus.

The developmental process of the fetus in vivo is divided into the first, second, and third trimesters, which are closely associated with the different developmental stages of the CNS. The first and second trimesters correspond to the neurulation, differentiation of cerebral vesicles, and neurogenesis.^1–3 Disorders of migration are more likely to occur in the second trimester. Either undermigration or overmigration of neurons will lead to cortical abnormalities, such as gray matter heterotopia, agyria/pachygyria, heterotopia within the molecular layer (layer 1 of the cortex), and neuronal heterotopia.⁴ Therefore, it is important to study fetal brain development in the second trimester.The sulci first appear as shallow fossa and then develop into a deeper and more curved pattern on the cerebral cortex.^5,6 The timing of the appearance of these different types of sulci is so precise that neuropathologists consider sulcation to be a reliable estimation of GA and consequently a good marker of fetal brain maturation.⁶ Fetal sulcal development has been studied in neuropathology,⁵ with US⁷ and MR imaging in vitro⁸ and in vivo.⁶ However, few investigators have described the normal patterns of fetal sulcation with an MR imaging scanner of high magnetic strength.The dimensions of the developing fetal brain change rapidly in early life, and morphometric normative data are crucial for the assessment of normal maturation and diagnosis of brain anomalies.⁹ Currently, prenatal morphometric studies have been focused as early as 17 weeks GA,¹⁰ but only the linear biometric values were obtained on 2D images without 3D reconstruction of the fetal brain. In addition, the existing MR imaging postprocessing software with automated tissue segmentation widely used for adults is not suitable for the fetal brain,¹¹ and thus we still lack 3D reliable and consistent quantitative measurements of the fetal brain at the early developmental phase.In our study, we present a normal trajectory of fetal sulci development and obtain quantitative data of the fetal cerebral cortex during 12–22 weeks GA.     

正常成人大脑白质纤维各向异性特征的弥散张量磁共振成像研究

目的：利用弥散张量磁共振成像研究正常成人大脑白质纤维的各向异性特征。材料和方法：应用弥散张量磁共振成像方法，观察10例正常志愿者的大脑白质纤维的FA图像，分别测量两侧大脑半球相对称的5个感兴趣区即外囊、内囊前肢、内囊后肢、胼胝体前部、胼胝体后部的FA值，并进行比较。结果：在FA图像上可清楚地观察到大脑白质纤维结构，呈高信号，各个部位信号是不同的，胼胝体信号较其他部位高，尤以压部信号最高。5个感兴趣区的FA值是外囊0．41、内囊前肢0．48、内囊后肢0．71、胼胝体前部0．72、胼胝体后部0．86。各个兴趣区之间进行秩和检验，结果为胼胝体后部与外囊比较有统计显著差异，胼胝体后部与内囊前肢比较有统计显著差异，胼胝体前部与外囊相比较亦有统计显著差异，其余各兴趣区之间相比较无统计显著差异。结论：弥散张量磁共振成像方法有效地显示大脑白质纤维的各向异性特，缸，为正确认识大脑白质纤维的正常解剖提供更多有价值的信息。     

磁敏感成像在脑微出血诊断中的应用价值

目的：探讨磁敏感成像（SWI）对脑微出血的诊断价值,以及对临床利用溶栓药物治疗脑梗死可能出现的脑出血等潜在危险的预见性。方法：66例原发性高血压患者,通过常规T1WI及T2WI检查,根据是否存在脑梗死或腔隙脑梗死分为存在基础病变的高危组（44例）和无基础病变的对照组（22例）。分析两组患者SWI序列显示脑微出血灶的阳性率。结果：所有受检者SWI显示满意。统计分析两组病例在SWI序列中脑微出血灶的个数以及病灶出现的部位。22例对照组中,SWI阳性者为3例。44例高危组中,阳性者为21例。24例阳性患者中,微出血灶出现在基底节区15例,出现在枕、顶、颞、额叶皮层共9例。结论：SWI在检出脑微出血灶方面有明显的优势。对于存在脑梗死等基础病变的高血压患者,SWI显示脑微出血灶的阳性率明显高于单纯高血压患者,可为临床应用溶栓药治疗脑梗死时提供参考。     

脑裂头蚴病的MRI表现及相关病理改变

目的 分析脑裂头蚴病的MRI表现及MRI对该病的诊断价值. 方法 回顾性分析8例经手术病理证实的脑裂头蚴病的MRI表现. 结果 8例脑裂头蚴病的MRI表现在T_1WI上为低信号、T_2WI上为高信号,病灶周围可见大片水肿信号影.增强后大部分病灶呈类似虫体形态的环状、结节状、串珠状及扭曲的线条样强化影.其中3例多次MRI复查,病灶的位置及形态有改变.结论 脑裂头蚴病的病理表现具有一定的特征性,MRI对此病的诊断和鉴别诊断有重要的临床意义.     

MRI弥散和灌注成像诊断超早期脑梗死的实验研究

目的评价磁共振弥散成像(DWI)和灌注成像(PWI)技术在超早期脑梗死中的诊断价值。方法新西兰白兔42只,随机分为7组,其中6组为实验组,1组为假手术组。采用改良O’Brein法闭塞兔一侧大脑中动脉制作局灶性脑缺血模型,对照组仅暴露同侧大脑中动脉,不予电凝。术后0.5、1、2、3、4、6 h不同时间段进行MRI扫描。结果常规MR序列显示缺血病灶明显晚于DWI和PWI。随着时间延长病灶各参数有特征性变化规律。在DWI和PWI中缺血区体积均随时间的延长不断扩大,两者不匹配区随时间延长逐渐缩小。结论DWI和PWI在诊断超早期脑梗死上优于常规MR序列。     

正常前列腺MRI定量测定

目的定量分析正常前列腺各径线MR测量值,建立正常前列腺体积标准。方法选取30例正常成年男性,按其年龄段分为4组。MRI测量前列腺和中央腺的前后、左右、上下径,并计算其体积、重量以及中央腺体积占前列腺总体积的比例。结果正常前列腺前后径为(3.02±0.47)cm,左右径为(4.19±0.52)cm,上下径为(3.24±0.34)cm,总体积为(22.01±7.48)cm3,重量为(23.11±7.86)g。不同年龄段前列腺前后径、左右径、体积及重量存在显著性差异。正常前列腺中央腺前后径为(2.01±0.41)cm,左右径为(2.06±0.34)cm,上下径为(2.01±0.32)cm,体积为(4.46±1.74)cm3,重量为(4.68±1.82)g,正常前列腺中央腺占前列腺总体积的比例为20.4%。不同年龄段的中央腺体积和重量存在显著性差异。正常前列腺静脉期中央腺强化幅度高于外周带强化幅度(P=0.0001)。结论年龄与前列腺总体积及中央腺体积呈正相关,即随着年龄增长,前列腺体积及中央腺体积逐渐增大。     

Review of Quantitative Knee Articular Cartilage MR Imaging

Osteoarthritis (OA) is one of the most prevalent disorders in today’s society, resulting in significant socio-economic costs and morbidity. MRI is widely used as a non-invasive imaging tool for OA of the knee. However, conventional knee MRI has limitations to detect subtle early cartilage degeneration before morphological changes are visually apparent. Novel MRI pulse sequences for cartilage assessment have recently received increased attention due to newly developed compositional MRI techniques, including: T2 mapping, T1rho mapping, delayed gadolinium-enhanced MRI of cartilage (dGEMRIC), sodium MRI, diffusion-weighted imaging (DWI)/ diffusion tensor imaging (DTI), ultrashort TE (uTE), and glycosaminoglycan specific chemical exchange saturation transfer (gagCEST) imaging. In this article, we will first review these quantitative assessments. Then, we will discuss the variations of quantitative values of knee articular cartilage with cartilage layer (depth)- and angle (regional)-dependent approaches. Multiple MRI sequence techniques can discern qualitative differences in knee cartilage. Normal articular hyaline cartilage has a zonal variation in T2 relaxation times with increasing T2 values from the subchondral bone to the articular surface. T1rho values were also higher in the superficial layer than in the deep layer in most locations in the medial and lateral femoral condyles, including the weight-bearing portion. Magic angle effect on T2 mapping is clearly observed in the both medial and lateral femoral condyles, especially within the deep layers. One of the limitations for clinical use of these compositional assessments is a long scan time. Recent new approaches with compressed sensing (CS) and MR fingerprinting (MRF) have potential to provide accurate and fast quantitative cartilage assessments.     

长巨脑动脉的MR综合成像

目的探讨长巨脑动脉MR多种成像方法的综合诊断价值。资料与方法对8例长巨脑动脉患者的MRI表现,磁共振血管成像（MRA）及多平面重组（MPR）、曲面重组（CPR）显示的异常血管分布、形态、信号强度进行分析。结果MRI能够明确显示椎一基底动脉的异常血管结构,以及相邻脑组织或颅神经的受压改变;MRA可直观显示迂曲延长、增粗的异常血管全貌;MPR则可以综合上述两种成像方法,同时显示异常血管的全貌以及相邻脑组织或颅神经的受压改变;CPR可将异常血管在同一平面展示,对显示迂曲血管最敏感。8例均发生在椎一基底动脉系统,其中2例累及基底动脉全段和左侧椎动脉,2例并发脑干梗死。结论MRI和MRA、MPR及CPR相结合,有助于该病的全面综合评价。     

脑静脉及静脉窦血栓的MR征象分析

目的 总结脑静脉及静脉窦血栓形成(CVST)的MRI及MRV成像特点,提高对其影像诊断水平.资料与方法 回顾分析39例经DSA或临床随访证实的CVST患者的临床及影像资料.结果 所有病例均行MRI平扫,19例行增强扫描,26例行MR静脉成像(MRV).MRI平扫表现为静脉窦流卒信号消失(38/39),血栓信号随病程长短而不同,急性期(11/38),血栓于T2WI多呈低信号(7/11),T1WI呈等信号(6/11)或略高信号(5/11);亚急性期(17/38),T2WI多呈高信号(12/17)、T1WI也多呈高信号(14/17);慢性期(10/38),T2WI多呈高信号(8/10),T1WI多呈等信号(6/10).增强扫描急性及亚急性期血栓均表现为受累静脉窦充盈缺损,慢性期多表现为血栓明显不均匀强化(6/7),静脉窦壁增厚毛糙.67%(26/39)病例出现闭塞静脉窦相应引流区域脑组织肿胀甚至出血,增强扫描肿胀区可出现异常强化(8/17),脑膜亦可强化(6/17);同时在闭塞静脉窦引流区可见多发强化血管信号(12/17).23例26人次MRV均可显示闭塞静脉窦血流信号缺失,其中2例治疗后静脉窦再通显示为不规则血流信号形成.结论 MRI结合MRV是CVST首选的无创检查方法,有助于CVST的早期诊断及排除诊断.     

Preoperative Cerebral Oxygen Extraction Fraction Imaging Generated from 7T MR Quantitative Susceptibility Mapping Predicts Development of Cerebral Hyperperfusion following Carotid Endarterectomy

BACKGROUND AND PURPOSE:Preoperative hemodynamic impairment in the affected cerebral hemisphere is associated with the development of cerebral hyperperfusion following carotid endarterectomy. Cerebral oxygen extraction fraction images generated from 7T MR quantitative susceptibility mapping correlate with oxygen extraction fraction images on positron-emission tomography. The present study aimed to determine whether preoperative oxygen extraction fraction imaging generated from 7T MR quantitative susceptibility mapping could identify patients at risk for cerebral hyperperfusion following carotid endarterectomy.MATERIALS AND METHODS:Seventy-seven patients with unilateral internal carotid artery stenosis (≥70%) underwent preoperative 3D T2*-weighted imaging using a multiple dipole-inversion algorithm with a 7T MR imager. Quantitative susceptibility mapping images were then obtained, and oxygen extraction fraction maps were generated. Quantitative brain perfusion single-photon emission CT was also performed before and immediately after carotid endarterectomy. ROIs were automatically placed in the bilateral middle cerebral artery territories in all images using a 3D stereotactic ROI template, and affected-to-contralateral ratios in the ROIs were calculated on quantitative susceptibility mapping–oxygen extraction fraction images.RESULTS:Ten patients (13%) showed post-carotid endarterectomy hyperperfusion (cerebral blood flow increases of ≥100% compared with preoperative values in the ROIs on brain perfusion SPECT). Multivariate analysis showed that a high quantitative susceptibility mapping–oxygen extraction fraction ratio was significantly associated with the development of post-carotid endarterectomy hyperperfusion (95% confidence interval, 33.5–249.7; P = .002). Sensitivity, specificity, and positive- and negative-predictive values of the quantitative susceptibility mapping–oxygen extraction fraction ratio for the prediction of the development of post-carotid endarterectomy hyperperfusion were 90%, 84%, 45%, and 98%, respectively.CONCLUSIONS:Preoperative oxygen extraction fraction imaging generated from 7T MR quantitative susceptibility mapping identifies patients at risk for cerebral hyperperfusion following carotid endarterectomy.

Cerebral hyperperfusion following carotid endarterectomy (CEA) has been defined as a substantial increase in ipsilateral cerebral blood flow well above the metabolic demands of brain tissue following surgical repair of carotid stenosis.^1,2 Cerebral hyperperfusion syndrome after CEA is a complication of cerebral hyperperfusion;³ its characteristic features include unilateral headache, pain in the face or eyes, seizures, and focal symptoms secondary to intracerebral hemorrhage or cerebral edema.^1–4 Intracerebral hemorrhage has a low incidence (1%), but patients with this condition have a poor prognosis.⁵ Moreover, several studies have found that post-CEA hyperperfusion, even when asymptomatic, causes slight but diffuse damage to the ipsilateral cerebral cortex and white matter.^3,6,7 This damage that occurs after CEA hyperperfusion is a principal cause of the postoperative cognitive impairment observed in 10% of patients following CEA.^3,6,7Cerebrovascular autoregulatory mechanisms operate through dilation of precapillary resistance vessels that maintain CBF when reductions in cerebral perfusion pressure occur, and this is referred to as stage 1 ischemia.^3,8–10 However, the autoregulatory mechanism provides insufficient compensation for severe decreases in cerebral perfusion pressure, which then leads to decreased CBF, referred to as misery perfusion or stage 2 ischemia.^3,8–10 Thus, misery perfusion, which is defined as marginally sufficient cerebral blood supply relative to cerebral metabolic demand, is a situation with severely impaired cerebral hemodynamics.⁸ This condition occurs in patients with chronic steno-occlusive diseases of the internal carotid artery.⁸The risk factors for cerebral hyperperfusion include high-grade stenosis, poor collateral blood flow, contralateral carotid occlusion, and long-standing hypertension, and they often result in impaired cerebral hemodynamics.^11–14 When normal perfusion pressure is rapidly restored after CEA, hyperperfusion may occur in regions of the brain with impaired autoregulation due to chronic ischemia. This hypothesis is like the “normal perfusion pressure breakthrough” theory of Spetzler et al.^13,15 Indeed, preoperative misery perfusion in the affected cerebral hemisphere is reportedly associated with the development of cerebral hyperperfusion following CEA or carotid stent placement for cervical ICA stenosis.^16,17Misery perfusion is principally detected as an increased oxygen extraction fraction (OEF) on positron-emission tomography.⁸ Several approaches have been attempted to measure OEF by using MR imaging techniques.¹⁸ In general, these techniques use blood oxygen level–dependent effects induced by differences in magnetic susceptibility between oxy- and deoxyhemoglobin to quantify oxygenation in venous structures and/or brain parenchyma.^19–21 Quantitative susceptibility mapping (QSM) is a postprocessing technique for quantifying the magnetic susceptibility of venous structures and brain parenchyma from T2*-weighted magnitude/phase images, which can be easily obtained by commercial scanners.²² Indeed, a recent study has introduced an OEF measurement method based on the QSM technique and has demonstrated that cerebral OEF images generated from QSM at 7T MR imaging correlate with OEF images on PET and provide high sensitivity and high specificity for detecting misery perfusion in the middle cerebral artery territory in patients with unilateral chronic ICA or MCA steno-occlusive disease.²³The purpose of the present study was to determine whether preoperative OEF imaging generated from 7T MR QSM could identify patients at risk for cerebral hyperperfusion following CEA.