MR脑血流灌注成像在亚临床肝性脑病中的应用

目的用MR灌注成像技术评价亚临床肝性脑病(SHE)患者的脑血流灌注模式。方法对12例经神经心理试验诊断为SHE的患者和10例年龄和教育程度相匹配的健康志愿者进行MR平扫和灌注成像,分别测量双侧尾状核头、苍白球、壳核、丘脑和额叶白质的脑血容量(CBV)、脑血流量(CBF)和平均通过时间(MTT),并以同侧额叶脑白质作为参照进行统计分析。结果SHE患者各感兴趣区与白质的比值:CBV值分别是1.32±0.25、1.19±0.46、1.51±0.20、1.69±0.53;CBF值分别为1.64±0.50、1.61±0.65、2.06±0.61、2.23±0.75;MTT值分别是0.83±0.17、0.76±0.20、0.78±0.19、0.78±0.17。志愿者相应部位CBV值为1.32±0.33、1.02±0.29、1.44±0.37、1.66±0.57;CBF值为1.36±0.24、1.08±0.28、1.55±0.51、1.58±0.64;MTT值为0.95±0.18、0.91±0.19、0.93±0.15、0.93±0.13。SHE患者较正常组MTT明显缩短,双侧丘脑、右侧尾状核头达到统计学意义的降低(P<0.05);CBF明显升高,左侧苍白球达到统计学意义的升高(P<0.05);CBV无明显变化。结论SHE患者基底节区灌注增加是血流从皮质到基底节区的重新分布,这是对运动前区、运动区功能缺陷及注意力缺陷的代偿反应,与皮质-基底节-丘脑-皮质环路密切相关。     

动脉自旋标记MRI脑血流灌注成像在亚临床期肝性脑病患者的研究

目的 用动脉自旋标记(ASL)MRI灌注成像技术评价亚临床肝性脑病(SHE)患者基底节区的脑血流灌注模式.方法 对16例经神经心理试验诊断为SHE的患者和13例年龄和教育程度相匹配的健康志愿者进行MRI平扫和ASL灌注成像,分别测量双侧尾状核头、苍白球、壳核、丘脑和额叶白质的脑血流量(CBF),并以同侧额叶白质作为参照进行统计分析.结果 SHE患者各感兴趣区与白质的比值均高于对照组:CBF值右侧分别为0.88±0.17,1.01±0.06,0.96±0.13和0.93±0.10,左侧分别0.91±0.15,1.00±0.07,0.94±0.12和0.97±0.11,志愿者相应部位CBF值右侧分别为0.81±0.04,0.95±0.04,0.88±0.04和0.90±0.04,左侧分别为0.81±0.02,0.94±0.04,0.87±0.05和0.92±0.04.结论 ASL脑血流灌注成像探测到SHE患者基底节区的脑血流灌注是增加的.SHE患者基底节区灌注增加是血流从皮质到基底节区的重新分布.     

脑小血管病中认知障碍患者的低剂量双源CT脑灌注成像变化

目的 探讨脑小血管病患者出现认知障碍时低剂量双源CT脑灌注成像的变化。方法 釆用西门子低剂量双源CT对123例经磁共振成像证实存在脑小血管病患者行头颅CT灌注检查,用简易精神状态评分(MMSE)和蒙特利尔认知评分(MoCA)量表进行认知功能评估,分为正常组40例,轻度认知障碍组45例及痴呆组38例。使用西门子MMWP工作站后处理软件分别测量额叶白质、颞叶白质、丘脑和海马区域血流量(CBF)、血容量(CBV)、平均通过时间(MTT)。分析低剂量双源CT灌注值在脑小血管病认知障碍中的作用。结果 三组患者额叶白质CBF、CBV、MTT均有显著性差异,随着认知障碍的加重,额叶白质CBF、CBV逐步降低,而MTT逐步延长(P <0.05)。三组患者颞叶白质MTT比较差异有统计学意义,随认知障碍加重而延长(P <0.05),而CBF及CBV差异无统计学意义(P> 0.05)。三组间丘脑及海马区域CT各灌注指标均差异无统计学意义(P>0.05)。结论 脑小血管病患者发生认知障碍时低剂量双源CT脑灌注成像出现变化,额叶白质灌注异常更加明显(P <0.05)。     

低剂量CT血流灌注成像对阿尔茨海默病的诊断价值

目的 评价低剂量CT血流灌注成像对阿尔茨海默病(Alzheimer's disease,AD)的诊断价值.方法 根据临床诊断标准随机选择52例AD和30例健康对照组.对他们进行低剂量血流灌注扫描(CTPI),并在工作站上进行处理,生成伪彩图及进行灌注参数测量,灌注参数包括脑血容量(cerebral blood volume,CBV)、脑血流量(cerebral blood flow,CBF)、平均通过时间(mean transit time,MTT)和达峰时间(time to peak,TTP).选择双侧额叶皮质、双侧颞叶皮质、双侧海马、双侧基底节区域进行测量.结果 健康对照组的双侧额叶、颞叶、基底节和海马CBV、CBF值明显高于AD组,而AD组上述部位的MTT和TTP明显大于健康对照组,有统计学意义(P＜0.05).结论 AD患者伴有微循环障碍和缺血改变.低剂量CT灌注对AD的诊断有一定意义.     

三维动脉自旋标记技术在正常婴儿脑血流分析中的应用

目的：应用三维动脉自旋标记技术（3D ASL）观察0～1岁正常婴儿的脑血流量值（CBF）,分析大脑各部位灰质及白质CBF与年龄及性别的相关性。方法：收集44例正常婴幼儿（4 d～12个月）,均行MRI常规序列及3D ASL序列扫描。在CBF灌注图像上的额叶、顶叶、颞叶、枕叶的灰质及白质,尾状核、壳核、苍白球、丘脑选取ROI,记录其CBF值。比较脑组织两侧对称位置ROI的CBF值,分析性别及年龄对CBF值的影响。结果：各脑区两侧对称位置CBF值比较差异均无统计学意义（均P>0.05）;不同性别各脑区CBF值比较差异均无统计学意义（均P>0.05）;除颞叶白质（r=0.07,P>0.05）外,其他脑区的CBF值与年龄呈明显正相关,CBF值随年龄增长呈升高趋势。结论：3D ASL技术为评估年龄与CBF的关系提供了可靠的定量参数。     

256层螺旋CT脑灌注成像与颈内动脉狭窄的相关性研究

目的：应用256层螺旋CT探讨颈内动脉狭窄和闭塞与脑灌注降低的相关性。方法：对76例患者进行CTA和CTP联合检查,根据CTA图像选出颈内动脉无狭窄者为对照组,其余患者进行颈内动脉狭窄分级,分轻、中、重三级,每级独立分析研究。所有患者均选择感兴趣区进行脑灌注成像CBV、CBF、MTT、TTP测量,单侧颈内动脉狭窄者病变侧与健侧对比,进行配对t检验。双侧颈内动脉狭窄者与对照组对比,进行独立样本t检验。结果：颈内动脉无狭窄者共15例,CBV CBF MTT TTP值分别为（分水岭区2.5±0.6;38±12;5.4±0.6;21±6。基底节区5.5±0.4;95±15;3.2±1.1;20±5）。单侧颈内动脉狭窄者共33例,其中轻中度狭窄者各为12例,且CBV、CBF、MTT、TTP四项差异均无统计学意义（P〉0.05）,重度狭窄者9例,分水岭区CBF、MTT差异有高度统计学意义（P〈0.01）,TTP差异有统计学意义（P〈0.05）,CBV差异无统计学意义（P〉0.05）。基底节区MTT差异有高度统计学意义（P〈0.01）,CBF差异有统计学意义（P〈0.05）,CBV、TTP差异无统计学意义（P〉0.05）。双侧颈内动脉狭窄者共28例,重度狭窄者11例,CBF、MTT差异有统计学意义（P〈0.05）。结论：受侧枝循环等多种因素影响,颈内动脉重度狭窄或闭塞与脑内血流灌注降低有相关性,轻中度狭窄与脑灌注降低无明显相关性。     

急性一氧化碳中毒脑损伤的磁共振扩散张量成像

目的：利用磁共振扩散张量成像(DTI )评估急性一氧化碳(CO)中毒患者的脑结构损伤情况。方法25例急性(5.0 d±1.44 d) CO 中毒患者和37例性别、年龄、利手、受教育程度匹配的健康志愿者进行 DTI 扫描,获得扩散张量纤维束成像(DTT)图像,并分别测量双侧小脑半球(齿状核)、黑质、海马、额叶白质(侧脑室前角前下方、侧脑室体部上方)、尾状核头、苍白球、丘脑、内囊前肢、内囊后肢、枕叶白质(视中枢)、顶叶白质(侧脑室体部上方)及胼胝体膝部、压部共26个感兴趣(ROI)的各向异性分数(FA)值和表观扩散系数(ADC)值,进行组间配对 t 检验。结果病患组双侧苍白球、双侧内囊前肢、双侧黑质、右侧小脑、左侧额叶下部白质、右额叶上下部白质、胼胝体膝部的 FA 值显著低于对照组(P <0.05)。病患组右侧黑质、左侧苍白球的 ADC 值显著降低(P <0.05),病患组右额叶上下部白质及双侧枕叶白质 ADC 值显著升高(P <0.05)。结论急性 CO 中毒患者广泛脑微结构受损,提示脑微结构的原发损伤可能是 CO 中毒迟发性脑病潜在的病理生理基础。     

急性脑静脉闭塞CT灌注成像的实验研究

目的观察脑静脉闭塞模型脑实质损害区CT灌注成像（CTP）变化规律,探讨该模型在该病研究中的价值。方法新西兰大白兔28只,随机分为2组（实验组24只,对照组4只）。一侧颈内静脉注入醋酸纤维素聚合物（CAP）合并双侧颈外静脉结扎术后1、3、6、12、24和48h行CTP检查对各组模型的脑血流动力学改变进行观察。结果实验组21只造模成功,其中3h及12h组各有1只在CTP上无明显异常表现,有19只CTP检查示脑血流灌注异常。术后1～3h,病变区脑血容量（CBV）轻度增加或正常,脑血流量（CBF）轻度降低,平均通过时间（MTT）稍延长;6～12h后病变中心区主要表现为CBV和CBF降低,MTT延长,而病变边缘区CBV增加或正常或轻度降低,CBF降低,MTT缩短;12～24h后病变中心区和边缘区CBV和CBF均明显降低,MTT明显延长。各时段病变中心区和边缘区的CBV%、CBF%、MTT%的差异均有统计学意义（P值均〈0.05）。对照组未见上述各种异常表现。结论 CT灌注成像可准确、敏感地反映急性脑静脉闭塞模型的血流动力学改变。     

肝硬化患者脑改变的磁化传递成像定量研究

目的 利用磁化传递成像（MTI）评价肝硬化患者是否存在异常的脑改变,探讨其与静脉血氨值、苍白球指数（GPI）及神经心理学测试之间的相关性. 资料与方法 48例肝硬化患者和30名健康志愿者,在T1WI上分别测量壳核和苍白球的信号值计算GPI.在MTI中将感兴趣区（ROI）置于双侧顶叶白质、额叶白质、枕叶白质、尾状核头、壳核、苍白球、丘脑,计算右侧各部位的磁化传递率（MTR）. 结果 （1）患者组各部位的MTR明显低于正常对照组,差异有统计学意义（P均＜0.001）.苍白球的MTR降低最明显,约9%.（2）对于Child分级和肝性脑病（HE）分级,顶叶、额叶、壳核、苍白球及枕叶白质的MTR差异均有统计学意义（P均＜0.05）,两两比较后显示,上述部位的MTR在Child A和B级、A和C级之间差异有统计学意义,B和C级之间差异则无统计学意义;在肝硬化、轻微型肝性脑病（MHE）及HE 3组患者之间差异无统计学意义.（3）顶叶、额叶、壳核、苍白球及枕叶的MTR、GPI指标与Child分级呈负相关（P均＜0.05）,而仅苍白球的MTR与HE分级间呈负相关（r＝-0.291,P＝0.045）.（4）Pearson相关分析显示,顶叶、额叶、壳核、苍白球及枕叶的MTR、GPI与血氨之间没有相关性,与各神经心理学测试之间有相关关系（P均＜0.05）. 结论 肝硬化患者存在轻度脑水肿,其有随Child分级加重的趋势,由此,可部分解释肝硬化患者的认知功能改变.     

脑后部可逆性脑病综合征的CT、MRI诊断

目的探讨CT、MRI在诊断脑后部可逆性脑病综合征（PRES）中的价值。方法8例女性PRES患者中6例为孕妇，1例肺癌手术后化疗患者，1例高血压患者，均行MR静脉成像（MRV）、T1WI、T2WI、水抑制序列（FLAIR）成像及扩散加权成像（DWI）；其中2例行CT平扫，5例行增强MRI及三维增强MR血管成像（3DCEMRA）。结果CT示病灶呈低密度，边界不清。8例患者MRV显示脑静脉、静脉窦通畅，无狭窄、异常扩张及血栓形成征象。MRI显示双侧顶枕叶（8例）、基底节区（2例）、额叶（4例）多发异常信号，主要位于双侧顶枕叶皮质下白质内，3例患者皮质亦受累。在T1WI病灶呈等或略低信号，T1WI及FLAIR呈高信号，以FLAIR像显示皮质病变为佳。DWI显示大部分病灶呈等信号，表观扩散系数（ADC）图呈等或高信号。部分病灶DWI及ADC图均表现为高信号。随访MRI显示所有患者病灶范围、数目逐渐变小、减少。5例行增强扫描患者显示病灶呈轻度强化，3D CEMRA显示强化沿双侧大脑前动脉、大脑中动脉及大脑后动脉终末支分布，部分呈“葡萄状”。随访增强扫描显示病灶强化范围及程度逐渐缩小、消失。结论FRES好发于顶枕叶白质，但也可见于基底节、额叶及脑皮质。病变为血管源性水肿，增强T1WI及3D CEMRA显示病灶有可逆性强化。以MRFLAIR及T2WI序列显示病灶最佳。     

与帕金森有关的亚临床期肝性脑病的MRI表现

目的:研究亚临床期肝性脑病患者锥体外系症状及MRI表现。方法:选择经神经心理测试诊断为亚临床期肝性脑病的患者12例,其中10例有明确的帕金森症状和其他锥体外系的症状,使用UPDRS(unified parkinson disease ratingscale)量表评价帕金森症状,所有患者行头部MRI检查。结果:10人有明确的帕金森症状,包括运动迟缓、肌强直、姿势性震颤等。所有患者MRI扫描都显示T1WI像苍白球对称的高信号。结论:亚临床期肝性脑病患者常表现为T1WI像高信号,并伴有帕金森症状,它与锰异常沉积于基底节区导致基底节功能受损有关。     

320排容积CT全脑灌注成像扫描协议优化研究

目的 探讨320排容积CT全脑灌注成像扫描协议优化的可行性。方法 20名健康志愿者按随机数字表法分为对照组和试验组,对照组7例,选择标准灌注扫描协议（19圈容积采集）;试验组13例,通过合理改变采集间隔,减少扫描期相,采用一组新的灌注扫描协议（11圈容积采集）。图像分析感兴趣区（ROI）设为两侧额叶白质、顶叶白质、半卵圆区、基底节区、枕叶、小脑,大小约（20±2）mm²。计算得到各感兴趣区的灌注参数值,包括脑血容量（rCBV）、达峰时间（TTP）、脑血流量（rCBF）、平均通过时间（MTT）及延迟时间（DT）。结果 试验组剂量长度乘积（DLP）和有效剂量（E）较对照组降低了42.02%。两组不同层面左右两侧ROI区的各灌注参数的差异无统计学意义。两组组间上述各个对应部位的ROI区各灌注参数无明显差别。结论 优化后的扫描协议得到了与厂家推荐的标准协议无差异的全脑灌注参数值且降低了辐射剂量,推荐常规使用。     

CT脑灌注联合血管成像在烟雾病血管重建术中的应用价值

目的探讨CT灌注(CTP)联合CT血管成像(CTA)分析在烟雾病(MMD)血管重建术中的意义。方法对18例烟雾病患者于术前及直接重建术后1周、间接重建术后3个月分别行CTP、CTA检查,对手术前、后术侧额、颞叶的CBV、CBF、MTT、TTP进行定量、定性及对比分析,评估颈内、颅内、外动脉的血管情况,为血管重建术术前制定手术方案、选择手术侧别,术后评价吻合血管的通常及手术疗效。结果 18例患者中1例行直接重建,术后吻合血管通畅,手术后术侧额、颞叶与术前比较,CBV、CBF增加,MTT不变、TTP延长,17例行间接重建,术后侧枝吻合血管形成,手术前、后术侧额、颞叶比较,CBF、CBV增加,MTT、TTP降低,差异有统计学意义(P0.05)。结论 CTP联合CTA能获得血管成像及全脑灌注成像,有助于MMD术前治疗方法的选择和术后疗效观察。     

不同管电流对正常颅脑CT灌注参数和辐射剂量的影响

目的分析管电流与正常颅脑各灌注参数及图像质量之间的关系,探讨低电流颅脑CT灌注扫描的可行性。资料与方法 2010年7月至2011年5月所有拟行颅脑CT灌注检查的受检者,按管电流随机分为A组(常规剂量组)(200 mA),B组(150 mA),C组(120 mA),D组(100 mA)不同管电流进行扫描,每组筛选10例无颅脑疾病者进行研究。在额叶、颞叶及小脑白质对称各选取3个感兴趣区,分别测量脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)和达峰时间(TTP),噪声(SD)及辐射剂量(E),计算对比度噪声比(CNR)、变异系数(CV)及信噪比(SNR),并对各参数进行统计学分析,记录各组辐射剂量。结果各兴趣区各项灌注参数在4组间比较差异无统计学意义。在4组间两两比较结果显示,A组与D组额叶、颞叶、小脑CBF及额叶、颞叶CBV组间两两比较差异有统计学意义,A组与C组颞叶CBF及额叶CBV组间两两比较差异有统计学意义,A组与B组各项灌注参数组间两两比较差异无统计学意义。各组客观图像质量指标在4组间比较差异显著,而在4组间两两比较结果显示A组与B组CNR差异无统计学意义。随着电流的降低,CV、SD有升高趋势,SNR有降低趋势。A～D组的吸收剂量分别为2.39 mSv、1.79 mSv、1.43 mSv、1.2 mSv。结论以150 mA的低管电流行颅脑CT灌注扫描对灌注参数和图像质量无明显影响,与常规剂量组对比辐射剂量降低25%,可用于低剂量颅脑CT灌注扫描。     

Relationship between cerebral perfusion in frontal-limbic-basal ganglia circuits and neuropsychologic impairment in patients with subclinical hepatic encephalopathy.

Early detection of neuropsychologic impairment in cirrhotic patients with subclinical hepatic encephalopathy (SHE) is important for their prognosis and quality of life. Abnormal MRI and MR spectroscopy (MRS) findings have been proposed as early markers of brain damage in these patients, but the role of functional neuroimaging in this field still has to be defined. In this study, the SPECT perfusion pattern in patients with SHE was investigated, and the relationship between regional cerebral blood flow (rCBF) and the MRI, MRS, neuropsychologic evaluation and biochemical data of these patients was assessed. METHODS: Data were obtained from 13 cirrhotic patients with SHE and 13 age-matched healthy volunteers. Fasting venous blood ammonia and manganese sampling and a battery of standardized neuropsychologic tests related to basal ganglia function and sensitive to the effects of liver disease were all performed on the same day. MRI and 99mTc-hexamethyl propyleneamine oxime SPECT were performed within 2 wk. RESULTS: A pattern of decreased prefrontal rCBF was found in patients with SHE compared with healthy volunteers. Basal ganglia and mesial temporal rCBF correlated inversely with performance on motor tasks involving speed (Purdue pegboard test) and frontal premotor function (Luria graphic alternances and Stroop tests). Thalamic rCBF correlated positively with T1-weighted MRI signal hyperintensity in the globus pallidus and with abnormal MRS findings. Neither the MRI signal intensity of the globus pallidus nor MRS correlated with neuropsychologic test results. CONCLUSION: Cirrhotic patients with SHE show a SPECT pattern of impaired prefrontal perfusion that does not seem to account for their neuropsychologic deficits. On the other hand, perfusion in some parts of the limbic system and limbic-connected brain regions, such as the striatum and the mesial temporal regions, increased with neuropsychologic impairment. These findings suggest that brain SPECT may be more sensitive than MRI in delineating cirrhotic patients requiring in-depth clinical testing to reveal basal ganglia-related neuropsychologic alterations.     

笑气滥用患者的脑血流灌注显像

目的:探讨N 2O(笑气)滥用所致脑血流量(CBF)的改变。 方法:回顾性分析2017年12月至2018年10月间于中日友好医院就诊的24例笑气滥用患者[男9例,女15例,年龄18~32(24.0±8.9)岁]脑血流灌注显像图,计算各脑区(基底节、脑中央区、小脑、扣带回、额叶、内侧颞叶、枕叶、顶叶...     

PURE技术校正MRI信号强度评价亚临床肝性脑病的临床应用价值

目的:评价PURE技术校正MR I信号强度在亚临床期肝性脑病患者中的应用价值。材料和方法:选取亚临床期肝性脑病12例,分别使用鸟笼标准线圈和使用PURE技术校正前后的八通道线圈进行头颅T1 flair像的扫描。选择苍白球、额叶白质和背景噪声作为感兴趣区,测量信号强度,计算苍白球对额叶白质的信号强度比及苍白球对噪声的信号强度比。结果:在应用PURE技术前,8通道线圈测量的信号强度低于标准鸟笼线圈,应用PURE技术后,差别消失。8通道相控阵线圈测得的信噪比明显高于鸟笼标准线圈的信噪比。结论:PUR技术的应用可以满意地解决信号不均匀的问题,有利于亚临床期肝性脑的诊断。     

The effect of varying user-selected input parameters on quantitative values in CT perfusion maps

RATIONALE AND OBJECTIVES: Deconvolution-based software can be used to calculate quantitative maps of cerebral blood flow (CBF), cerebral blood volume (CBV), and mean transit time (MTT) from first-pass computed tomography perfusion (CTP) datasets. The application of this software requires the user to select multiple input variables. The purpose of this study was to investigate the degree to which both major and minor variations of these user-defined inputs would affect the final quantitative values of CBF, CBV, and MTT. MATERIALS AND METHODS: A neuroradiologist constructed CBF, CBV, and MTT maps using standard methodology with commercially available software (GE Functool Version 1.9s) from CTP datasets of three acute stroke patients. Each map was reconstructed multiple times by systematically and independently varying the following parameters: postenhancement and preenhancement cutoff values, arterial and venous region-of-interest (ROI) placement, and arterial and venous ROI size. The resulting quantitative CTP values were compared using identical ROIs placed at the infarct core. RESULTS: Major variations of either arterial ROI placement or arterial and venous ROI size had no significant effect on the mean CBF, CBV, and MTT values at the infarct core (p > .05). Even minor variations, however, in the choice of venous ROI placement or in pre- and postenhancement cutoff values significantly altered the quantitative values for each of the CTP maps, by as much as threefold. CONCLUSION: Even minor variations of user-defined inputs can significantly influence the quantitative, deconvolution-based CTP map values of acute stroke patients. Although quantitation was robust to the choice of arterial ROI placement and arterial or venous ROI size, it was strongly dependent on the choice of venous ROI location and pre- and postenhancement cut-off values. Awareness of these results by clinicians may be important in the creation of quantitatively accurate CTP maps.     

Variability of clinical CT perfusion measurements in patients with carotid stenosis

Introduction CT perfusion imaging (pCT) may be used to detect and monitor hemodynamic abnormalities due to cerebrovascular disease. The magnitude of variability in clinical measurements has been insufficiently evaluated. The purpose of this study was to measure the long-term variability of clinical pCT measurements in patients with cerebrovascular disease. Methods pCT parameters were calculated for the cerebral hemisphere contralateral to a carotid stenosis before and after stent treatment of stenosis in 33 consecutive patients. Mean transit time (MTT), cerebral blood flow (CBF), and cerebral blood volume (CBV) calculated from pCT data from both a small and large region of interest (ROI) using both manual and automated methods were compared before and after stent treatment. Differences between the first and second measurement were tested for statistical significance with at-test. Variability was calculated as the standard deviation of the differences divided by the mean of the pre- and post-stent treatment values. To adjust for proportional bias, the Bland–Altman analysis was applied. Results The differences between the two measurements of MTT, CBF, and CBV averaged 2.5 to 7.7% when a manual method was used and was higher with automatic methods (p > 0.07). The variability of the values was 18% for MTT, 19% for CBV, and 25% for CBF with the large ROI and the manual method of calculation. The magnitude was larger when the small ROI and automatic methods were employed. Conclusion Longitudinal measurements of MTT, CBV, or CBF by pCT may vary by 20–25%. To detect changes in treatment-related changes in perfusion, pCT studies must be designed to achieve statistical significance based on this variability.     

The effect of scan interval and bolus length on the quantitative accuracy of cerebral computed tomography perfusion analysis using a hollow-fiber phantom

The shuttle scan technique is expected to extend scan range in cerebral computed tomography (CT) perfusion by 16- or 64-row multidetector CT (MDCT), but it may affect quantitative accuracy. This study aims to evaluate the effect of long scan interval and bolus length on the quantitative accuracy of perfusion indices using an innovative hollow-fiber phantom.We used an originally developed hollow-fiber hemodialyzer covered with polyurethane resin as a perfusion phantom. We scanned the phantom during various scan intervals (1–13 s) and bolus injection lengths (5, 10, 15, and 20 s), and evaluated cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-peak (TTP). We verified the influence on measured values using a two-way analysis of variance (ANOVA). All measured CBF values were smaller than the theoretical CBF values, and all the measured MTT values were larger that the theoretical MTT values (95% confidence interval). Extended scan intervals resulted in more overestimation of MTT and more underestimation of CBF (p < 0.001). CBV is not affected by the change in scan interval (p < 0.001), and a longer bolus length improved the underestimation of CBV (p < 0.001). Extended scan intervals resulted in the loss of quantitative accuracy in MTT, even with longer bolus injection length, while quantitative CBF values were underestimated and TTP values overestimated. The CBV measurement was not affected by the change in scan interval, and a longer bolus injection improved the accuracy of these measurements.