Effect of scanning pressure on intracranial hemodynamics during transfontanellar duplex US.

The purpose of this study was to determine the effect of transducer scanning pressure during duplex ultrasonographic evaluation of intracranial hemodynamics in newborns. Doppler spectra were obtained from the anterior cerebral artery with use of light and firm scanning pressure over the anterior fontanelle in 23 healthy infants and 20 infants with reduced cranial compliance due to ventricular dilatation, intracranial hemorrhage, diffuse cerebral edema, and extraaxial fluid. In healthy infants, the mean resistive index (RI) increased from 69.9 +/- 3 to 74.8 +/- 3 (P < .005), and mean time average velocity (TAV) decreased from 11.1 cm/sec +/- 1.3 to 8.6 cm/sec +/- 1.3 (P < .0001) with firm scanning pressure. In infants with decreased cranial compliance, mean RI increased from 67.8 +/- 4 to 85 +/- 5, and mean TAV decreased from 16.3 cm/sec +/- 2 to 10.7 cm/sec +/- 2 (P < .0001 for both comparisons). A significant alteration in RI with firm technique (> or = 20% increase in RI, or reversal of diastolic flow) was observed in 12 of 28 examinations in infants with decreased cranial compliance and in only one of 23 healthy infants (P < .005). These data show that scanning pressures during duplex ultrasonography can significantly affect intracranial hemodynamics, especially in infants with altered cranial compliance.     

肾血流动力学改变在窒息新生儿肾损伤中的诊断价值

目的 探讨肾血流动力学改变在窒息新生儿肾损伤中的早期诊断价值.资料与方法 根据Apgar评分标准将60例新生儿分成轻、重度窒息组及健康对照组,每组20例.运用彩色多普勒超声检测肾主动脉收缩期峰值速度(Vs)、舒张期末血流速度(Vd)及阻力指数(Rl),并测定血清尿素氮(BUN)、肌酐(Cr)及尿内皮素-1 (ET-1)水平.依据健康对照组设立正常参考值上、下限,高于上限或低于下限视为异常.同时分析各组间指标的变化及相关性.结果 各窒息组Vs、Vd、RI及ET-1异常发生率更高,与健康对照组比较,差异有统计学意义(P＜0.01).各窒息组BUN、Cr异常发生率低,仅重度窒息组与健康对照组比较,差异有统计学意义(P＜0.01).窒息患儿Vs、Vd与BUN、Cr、ET-1之间呈负相关(P＜0.01),RI与BUN、Cr、ET-1之间呈正相关(P＜0.01).结论 窒息新生儿早期肾损伤伴有肾血流动力学改变,且与窒息程度相关,提示肾动脉血流动力学参数可作为判定窒息新生儿早期肾损伤的敏感指标.     

Cortical perfusion assessment with 123I-isopropyl amphetamine (123I-IAMP) in normal pressure hydrocepha lus (NPH)

NPH can be reversible after cerebrospinal fluid (CSF) diversion. In the past no reliable criteria could be defined to predict the successful outcome of CSF shunting. Several authors demonstrated an increased cerebral blood flow after lumbar puncture in patients with NPH, indicating an underlying impairment of cerebral circulation autoregulation. 123I-AMP brain tomoscintigraphy was applied to 23 individuals with NPH before and after CSF drainage. Of these 23 patients, 10 underwent surgical shunting. The frontal and parietal hypoactive cortical pattern was present in NPH but not pathognomonic. Under stimulation of CSF pressure lowering, seven patients with improved outcome after shunting demonstrated an increase of cerebral perfusion in these areas, whereas a decrease of activity was found in three patients whose clinical status was unchanged after CSF diversion. This tomoscintigraphic test may be an interesting additional criterion for surgical admission.     

Cortical perfusion assessment with 123I-isopropyl amphetamine (123I-IAMP) in normal pressure hydrocepha lus (NPH)

NPH can be reversible after cerebrospinal fluid (CSF) diversion. In the past no reliable criteria could be defined to predict the successful outcome of CSF shunting. Several authors demonstrated an increased cerebral blood flow after lumbar puncture in patients with NPH, indicating an underlying impairment of cerebral circulation autoregulation. ¹²³I-AMP brain tomoscintigraphy was applied to 23 individuals with NPH before and after CSF drainage. Of these 23 patients, 10 underwent surgical shunting. The frontal and parietal hypoactive cortical pattern was present in NPH but not pathognomonic. Under stimulation of CSF pressure lowering, seven patients with improved outcome after shunting demonstrated an increase of cerebral perfusion in these areas, whereas a decrease of activity was found in three patients whose clinical status was unchanged after CSF diversion. This tomoscintigraphic test may be an interesting additional criterion for surgical admission.     

CT perfusion parameter values in regions of diffusion abnormalities

BACKGROUND AND PURPOSE: Dynamic CT perfusion imaging is a rapid and widely available method for assessing cerebral hemodynamics in the setting of ischemia. Nevertheless, little is known about perfusion parameters within regions of diffusion abnormality. Since MR diffusion-weighted (DW) imaging is widely considered the most sensitive and specific technique to examine the ischemic core, new knowledge about CT perfusion findings in areas of abnormal diffusion would likely provide valuable information. The purpose of our study was to measure the CT-derived perfusion values within acute ischemic lesions characterized by 1) increased signal intensity on DW images and 2) decreased apparent diffusion coefficient (ADC) and compare these values with those measured in contralateral, normal brain tissue. METHODS: Analysis was performed in 10 patients with acute middle cerebral artery territory stroke of symptom onset less than 8 hours before imaging who had undergone both CT perfusion and DW imaging within 2 hours. After registration of CT perfusion and DW images, measurements were made on a pixel-by-pixel basis in regions of abnormal hyperintensity on DW images and in areas of decreased ADC. RESULTS: Significant decreases in cerebral blood flow and cerebral blood volume with elevated mean transit times were observed in regions of infarct as defined by increased signal intensity on DW images and decreased ADC. Comparison of perfusion parameters in regions of core infarct differed significantly from those measured in contralateral normal brain. CONCLUSION: CT perfusion findings of decreased cerebral blood flow, mean transit time, and cerebrovascular volume correlate with areas of abnormal hyperintensity on DW images and regions of decreased ADC. These findings provide important information about perfusion changes in acute ischemia in areas of diffusion abnormality.     

Duplex Doppler ultrasonography of intra-renal arteries. Normal and pathological aspects]

Duplex Doppler ultrasonography may explore renal perfusion in frequent diseases such as renal obstruction, reno-vascular hypertension, acute or chronic renal failure or diabetic renal complications by measuring Pourcelot's resistive index (RI) of renal parenchyma arteries for each kidney. A statistical and prospective study was performed on 574 patients. In healthy patients, the RI values, equal for each kidney were included in 0.45 and 0.7 (mean RI = 0.59). For other values, there was a renal pathology. Patients with idiopathic hypertension (mean RI = 0.59) or non obstructive dilatation (mean RI = 0.61) did not have an RI significantly different from healthy patients. In cases of renal obstruction, there was a significant increase in the RI for the pathological kidney (mean RI of 0.73). The sensitivity and the specificity was 100% for acute obstructions examined during the first 48 hours. In contrast, in case of renal artery stenosis greater than 70% there was a significant decrease in the RI for pathological kidney. So the RI increased significantly in both kidneys: when there was renal failure with active disease within the tubulo-interstitial compartment (mean RI of 0.77); in all cases of diabetic nephropathy (mean RI of 0.74) where the RI increased early before laboratory signs. Duplex Doppler ultrasonography may be an original method for renal explorations by providing not only morphological data but also physiological data with the perfusion study.     

3D-ASL技术在DWI及MRA检查为阴性短暂性脑缺血发作病人中的应用

目的探讨三维动脉自旋标记成像(3D-ASL)技术能否发现扩散加权成像(DWI)及MR血管成像(MRA)显示为阴性短暂性脑缺血发作(TIA)病人的脑血流灌注异常。方法回顾性分析112例经临床确诊而DWI及MRA阴性的TIA病人[男63例,女49例,平均年龄(58.41±4.92)岁]及67例健康志愿者[男35例,女32例,平均年龄(54.70±6.36)岁]的3D-ASL资料。将TIA资料依据症状分为单发作组(发作1次)与频发作组(1次)。3名医师共同观察动脉自旋标记(ASL)脑血流量(CBF)图并测量兴趣区相对CBF(r CBF值),计算r CBF比值(灌注异常区的r CBF值/镜像区r CBF值)。采用卡方检验比较两组资料构成有无差异,采用独立样本t检验比较两组r CBF比值有无差异。并判断TIA病人临床症状与灌注异常区是否具有一致性。结果 112例TIA病人中发现灌注异常者69例(61.6%),灌注正常43例(38.4%);健康受试者中灌注减低7例(10.4%),灌注正常60例(89.6%),TIA病人的灌注异常者明显多于健康受试者(χ2=44.91,P0.05),平均r CBF比值(0.78±0.19)低于健康受试者(0.96±0.15)(t=56.2,P0.05)。TIA症状单发作组与频发作组的r CBF值差异无统计学意义(t=0.34,P0.05)。69例灌注异常TIA中,颈内动脉系统TIA的临床症状与灌注异常区相匹配的50例;椎基底动脉系统TIA的临床症状与灌注异常区匹配为9例。结论 3D-ASL有助于发现DWI及MRA阴性的TIA的灌注异常,有利于明确TIA的早期病生理状态。     

Perioperative transcranial Doppler US to evaluate intracranial compliance in young children undergoing craniosynostosis repair surgery

PURPOSE: To determine whether measurements with transcranial Doppler ultrasonography (US) of resistive indexes (RIs) of basal cerebral arteries with pressure provocation can be used to identify infants and children with craniosynostosis who have abnormal intracranial compliance and to study the effects of surgery on compliance. MATERIALS AND METHODS: Transcranial Doppler US was performed through the temporal squama, fontanels, and existing skull defects prior to and immediately following cranioplasty. Twenty-four studies were performed in six patients with multisuture synostosis, and 61 studies were performed in 26 patients with single-suture synostosis. Study findings were compared with those of 23 control subjects and were characterized as normal or abnormal on the basis of age-specific normal criteria for RI. RESULTS: In multisuture synostosis, results of six of the nine preoperative transcranial Doppler US studies were abnormal. During postoperative follow-up, three recurrences requiring reoperation occurred, one of which was detected with abnormal transcranial Doppler US findings. In single-suture synostosis, results of seven of the 26 preoperative transcranial Doppler US studies were abnormal, and all occurred in young infants with sagittal and unicoronal synostosis. Immediate effects of surgery were variable. All patients with sagittal synostosis had a significant immediate postoperative increase in RI, which normalized during postoperative follow-up. There was no significant difference in RI between patients with successfully treated craniosynostosis and control subjects. CONCLUSION: Transcranial Doppler US can be used to identify patients with craniosynostosis with decreased intracranial compliance, and it is a suitable noninvasive test to monitor the effects of surgery on compliance.     

磁共振成像阴性的全面强直阵挛性癫痫发作间期SPECT研究

目的:研究MRI阴性的全面强直阵挛性发作癫痫(GTCS)患者在发作间期脑血流灌注特征.材料和方法:对60例MRI阴性的GTCS患者进行发作间期99mTc-ECD(双半胱乙脂)-SPECT脑血流灌注显像,10例年龄匹配的健康人作对照,计算感兴趣区(ROI)的不对称指数(%AI)并进行定量分析.将SPECT分析结果与患者的临床表现与EEG相比较.结果:60例MRI阴性的GTCS患者中29例表现为一侧丘脑、基底节区低灌注,其中4例为丘脑伴同侧颞叶低灌注,1例丘脑伴同侧颞叶及小脑低灌注,3例丘脑伴同侧枕叶低灌注,另有5例仅表现为一侧顶叶或颞叶低灌注,异常率为56.7%;而26例(43.3%)血流灌注无异常表现.脑血流灌注异常与正常的患者在性别、年龄、发病年龄、病程及EEG异常率方面无显著性差异(P＞0.05),而平均发作频率和总发作次数则具有显著性差异(P＜0.05).患者组和正常对照组在丘脑和基底节区的%AI存在显著性差异(P＜0.05).结论:①相当一部分MRI阴性GTCS患者存在发作间期脑血流灌注异常;②MRI阴性GTCS患者的脑血流异常灌注区主要分布在丘脑及基底节区而非皮质;③低灌注脑区可能是亚临床病灶或是癫痫反复发作所致的脑损伤区,这部分患者对药物治疗反应及预后不佳.     

Postpartum CT examination of the heads of full term infants

Summary Intracranial hemorrhage and decreased density of the cerebral parenchyma were the major findings on CT of 150 full term newborns in the first week of life. Clinically silent hemorrhage was rare. All neonates with severe intracranial bleeding had neurological abnormalities. A correlation was not found between hemorrhage and the mode of delivery. The site of hemorrhage has an important bearing on brain development. Periventricular hypodensity is an ambiguous finding which should be interpreted in conjunction with the clinical findings.     

Intracranial venous system in the newborn: evaluation of normal anatomy and flow characteristics with color Doppler US.

To establish the effectiveness of color Doppler ultrasound (US) in identifying flow in the intracranial venous system in newborns, 20 healthy, full-term newborns were scanned. Visualization of the subependymal and internal cerebral veins, superior sagittal sinus, vein of Galen, straight sinus, and left transverse sinus was accomplished in almost every newborn (greater than or equal to 90%). Mean blood flow velocities were as follows: subependymal veins, 3.0 cm/sec; internal cerebral veins, 3.3 cm/sec; inferior sagittal sinus, 3.5 cm/sec; vein of Galen, 4.3 cm/sec; straight sinus, 5.9 cm/sec; and superior sagittal sinus, 9.2 cm/sec. Flow in the subependymal and internal cerebral veins was continuous in all but one newborn (5%), while low-amplitude pulsations were observed with increasing frequency in the more central venous structures such as the vein of Galen (15%), straight sinus (32%), and transverse sinuses (36%). It was concluded that visualization of the intracranial venous system with color Doppler US is possible in the majority of healthy neonates.     

Correlation between renal vascular resistance, pulse pressure, and the resistive index in isolated perfused rabbit kidneys.

PURPOSE: To assess the effect of acute changes in renal vascular resistance (RVR) and pulse pressure on the resistive index (RI) measured by using Doppler ultrasonography (US). MATERIALS AND METHODS: Rabbit kidneys were perfused by using a pulsatile perfusion system in which RVR, systolic and diastolic pulse pressures, and pulse kinetics were controlled and monitored while simultaneously measuring the RI. RESULTS: When RVR was increased fivefold with phenylephrine hydrochloride, the RI increased only slightly (from 0.45 at baseline up to 0.50). There was a virtually linear relationship between the RI and the pulse pressure index ([systolic pressure-diastolic pressure]/systolic pressure) in the range of 0.30-0.80. The RI was not affected by the pulse rate or fraction of time that systolic pressure was applied during the pulse cycle. CONCLUSION: Contrary to conventional teaching, which is based on theoretic considerations, the RI is not readily affected by acute changes in RVR. This indicates a need to reconsider the conventional explanations used to explain increases in RI that are frequently found in patients with renal disease or ureteral obstruction.     

高压氧对新生儿缺氧缺血性脑病血浆内皮素-1、一氧化氮及脑血流动力学变化的影响

目的 探讨高压氧（HBO）对新生儿缺氧缺血性脑病（HIE）时血浆内皮素－1（ET－1）和一氧化氮（NO）含量的影响及其与脑血流动力学的关系。方法 对52例HIE新生儿在首次HBO治疗前后应用经颅多普勒超声（TCD）检测双侧大脑前，中，后动脉收缩峰流速（Vs)，舒张末期流速（Vd)，搏动指数（PI）和阻力指数（RI），同时用放射免疫法和硝酸还原酶法分别测定血浆ET－1和NO水平；另设足月，正常的新生儿15例为对照组，亦进行上述检测。结果 （1）脑血流示轻度组Vd,Vs局部降低，中，重度组Vd广泛降低，Vs呈局部降低，而重度组尤为显著（P均＜0．05）。HBO暴露后重度组左中动脉Vd仍低于对照组，其余与对照组之间差异均无显著性意义。（2）PI和RI在轻度组与对照组之间差异无显著性意义，在中度组则局部增高，而重度组双侧大脑动脉PI和RI广泛增高（P均＜0．05）。HBO暴露后PI和RI均降低，但与对照组之间差异无显著性意义。3）HIE各组NO和ET－1水平均高于对照组，且与病变程度成正相关。但NO／ET－1比值低于对照组（P均＜0．05），且重度组＜中度组＜轻度组，HBO暴露后HIE各组NO水平增高，ET－1水平下降（P均＜0．05），NO／ET－1比值升高，但各组之间差异无显著性意义。结论 HBO可能通过影响NO和ET－1水平而舒张脑血管和改善脑供血，在而对缺氧缺血性脑损伤具有保护作用。     

Autonomic control of cerebral circulation: exercise

On the basis of measurement techniques that require steady-state hemodynamic conditions when the measurement of cerebral blood flow (CBF) is being obtained, cerebral autoregulation (CA) maintains CBF stable over a wide range of cerebral perfusion pressures. When an acute (or dynamic) change in cerebral perfusion pressure (seconds) is imposed, CBF is not maintained. For example, after thigh cuff occlusion, its release induces an acute drop in arterial blood pressure (ABP). The sharp decrease in CBF indicates that CA was unable to respond to the dynamic (or rapid) changes in cerebral perfusion pressure. Therefore, control mechanisms of arterial pressure with short time constants must contribute importantly to CBF regulation. In order for CA to be effective, the cerebral perfusion pressure must lie within an autoregulatory range of perfusion pressures. The traditional thinking is that changes in sympathetic tone have a limited effect on CBF at rest. However, moderate- to heavy-intensity exercise causes only moderate increases in CBF despite large increases in sympathetic activity and ABP. Animal studies demonstrate that increases in sympathetic nerve activity cause cerebral vasoconstriction and protection against disruption of the blood-brain barrier. These findings suggest that the regulation of CBF during exercise is modulated not only by CA but also by autonomic nervous system and the arterial baroreflex-mediated control of the systemic circulation.     

Renal blood flow in pigs: changes depicted with contrast-enhanced harmonic US imaging during acute urinary obstruction.

PURPOSE: To evaluate contrast agent-enhanced harmonic ultrasonographic (US) imaging and Doppler hemodynamics during acute urinary obstruction. MATERIALS AND METHODS: In 12 piglets, the distal ureter was obstructed for 60 minutes, followed by intravenous injection of furosemide. In six piglets, ureteral pressure was further elevated to mean arterial pressure, and in six other piglets ureteral obstruction was released. Contrast-enhanced harmonic imaging was performed, and interlobar resistive index (RI) and renal blood flow were determined at baseline and during each experimental condition. A bolus injection curve was constructed by plotting mean pixel intensity versus time, and the area under this normalized curve was compared with renal blood flow values. RESULTS: Ureteral obstruction and high ureteral pressure reduced cortical renal blood flow to 88% and 66%, respectively, of baseline values. Administration of contrast agent resulted in marked homogeneous enhancement of the renal cortex. The area under the curve diminished during ureteral obstruction and correlated well with mean cortical blood flow. RI correlated well with renal perfusion pressure but poorly with changes in renal blood flow. CONCLUSION: Contrast-enhanced harmonic US imaging depicts changes in renal blood flow during acute obstruction. Interlobar RI is a good predictor of renal perfusion pressure but not of changes in renal blood flow.     

微机辅助CT脑灌注成像以及定量测量

目的：报告微机辅助CT脑灌注成像以及定量测量方法。方法：以PentiumⅡ300MHz微处理器，128MB内存，16MB显存，6G硬盘PC机和Windows98第2版为平台，用VissualC 为开发语言，根据中心容积定理，利用动态CT图像分析并计算脑血流动力学的有关参数，包括脑血流量（cerebral blood flow,CBF)，脑血容量（cerebral blood volume,CBV),平均通过时间（mean transit time,MTT)和峰值时间（time to peak,TTP)等。最后，将脑血流动力学数据根据色阶分别处理成脑血流量图（mapping of CBF)，脑血容量图（mapping of CBV)，平均通过时间图（mapping of MTT)和峰值时间图（mapping of TTP)。结果：动态增强CT图像经软件处理后可以在微机上显示脑组织的CBF，CBV，TTP和MTT灌注原始图像以及分割颅骨，皮下组织和脑室后的图像。急性脑缺血患者在MR T1加权像，T2加权像，平扫CT以及增强CT未显示的责任病灶，脑CT灌注图像可以清楚显示脑血流动力学的异常。结论：微机辅助CT脑灌注成像简单铁行，可显示常规CT和MR无法发现的早期脑缺血区的血流异常。与MR灌注成像相比更适用于急诊检查。     

多囊卵巢综合征的子宫内膜厚度及卵巢血液改变的超声诊断

目的探讨多囊卵巢综合征(PCOS)的子宫内膜厚度及卵巢血液改变的超声诊断价值。方法对47例多囊卵巢综合征患者(PCOS组)和32例健康人(对照组)进行超声检查,观察子宫内膜的厚度及卵巢血液参数变化。结果PCOS组的子宫内膜厚度和收缩期峰值血流速度(PSV)明显大于对照组,差异有统计学意义(P<0.05),不同停经天数PCOS患者的子宫内膜厚度和卵巢PSV差异有统计学意义,以>90 d组的值最高;PCOS组和对照组卵巢的阻力指数(RI)差异有统计学意义,PCOS组明显低于对照组(P<0.05),不同停经天数PCOS患者的卵巢RI值差异有统计学意义,以>90 d组的值最低。结论超声检查显示PCOS患者的子宫内膜增厚,卵巢血流丰富,阻力明显减低,并且随停经时间而变化。超声诊断对于PCOS具有重要的临床意义。     

64层螺旋CT脑灌注成像评价急性脑梗死溶栓前后脑血流动力学改变

目的探讨64层螺旋CT脑灌注成像(CTP)在评价急性脑梗死溶栓疗效中的应用价值。资料与方法20例急性脑梗死患者于发病3~10h行常规CT平扫和CTP检查,其中16例行静脉溶栓、4例行动脉溶栓治疗。溶栓后2~7天复查CT平扫和CTP。对溶栓治疗前后病变区的脑血流量(CBF)、脑血容量(CBV)和达峰时间(TTP)进行定性和定量比较分析。结果20例中5例头颅CT平扫发现早期脑梗死征象,15例常规CT平扫未发现异常,CTP均发现与临床症状对应的脑灌注异常区,表现为CBF、CBV降低,TTP延迟。溶栓后15例脑灌注异常范围缩小,CBF和CBV增加,TTP缩短;3例脑灌注异常区范围扩大,CBF、CBV进一步降低,TTP延迟更加显著;2例出现局部过度灌注。统计学分析结果显示溶栓治疗后多数患者脑灌注情况明显改善,缺血边缘区CBF和TTP与溶栓前差异有统计学意义(P<0.05),缺血中心区CBF和CBV与溶栓前差异无统计学意义(P>0.05)。结论脑CTP检查能够观察溶栓治疗前后脑血流动力学指标的变化,为评价急性脑梗死患者的溶栓疗效提供重要依据。     

Increased anisotropy in neonatal meningitis: an indicator of meningeal inflammation

Introduction Increased anisotropy in brain abscesses has been shown to be due to adhesion of inflammatory cells and is suggestive of an active inflammatory process. The objective of this study was to determine if similar changes occur in the pia-arachnoid on the surface of the cerebral cortex in patients with pyogenic meningitis, and if these changes regress following antibiotic therapy. Methods Diffusion tensor imaging (DTI) was performed on 14 term neonates (mean age 13 days) with bacterial meningitis and 10 healthy age- and sex-matched controls. Regions of interest (ROIs) were placed on areas including the leptomeninges, the cerebral cortex and adjoining subcortical white matter for quantitation of mean fractional anisotropy (FA) and diffusivity (MD) values. Follow-up MRI was performed in five of the neonates in the patient group after 2 weeks of antibiotic treatment. FA and MD values were compared in patients before and after antibiotic treatment as well as with those in the healthy controls. Results Significantly higher FA values but no difference in MD values were observed in the patient group as compared to the healthy controls at both time points (before and after antibiotic treatment). Significantly decreased FA values in the frontal, occipital and temporal cortical regions were observed in patients following antibiotic treatment. Conclusion DTI-derived FA may be of value in the noninvasive assessment of meningeal inflammatory activity and treatment response in neonates.     

Acetazolamide stress brain-perfusion SPECT predicts the need for carotid shunting during carotid endarterectomy.

Although carotid shunting is occasionally necessary to prevent cerebral ischemia during carotid endarterectomy, there is no reliable indication for this procedure. The purpose of this study was to evaluate whether acetazolamide stress brain-perfusion SPECT can predict the need for carotid shunting during carotid endarterectomy. METHODS: Basal and acetazolamide stress brain-perfusion SPECT imaging was performed using a 1-d protocol and 99mTc-ethylcysteinate dimer (ECD) in 75 patients (12 women, 63 men; mean age, 64.8 y) before carotid endarterectomy. The need for carotid shunting during carotid endarterectomy was determined by the development of neurologic deterioration after carotid clamping under regional anesthesia. Regional cerebral blood flow, cerebrovascular reserve, the presence of contralateral carotid stenosis (> or =70%), and clinical risk factors, including age, sex, history of minor stroke or transient ischemic attack, diabetes mellitus, hypertension, and smoking, were assessed with regard to whether they could predict the need for shunting. RESULTS: Carotid endarterectomy was performed safely without carotid shunting in 61 of 75 patients (81.3%). Carotid shunting was required in 14 patients (18.7%). Seven of 21 patients with a contralateral carotid stenosis, 9 of 41 with a reduced regional cerebral blood flow, and 11 of 30 with a reduced regional cerebrovascular reserve underwent carotid shunting. Patients with a reduced cerebrovascular reserve had a significantly higher number of carotid shunts performed (P < 0.01) than did those with a normal reserve, whereas contralateral carotid stenosis (P = 0.054) showed borderline significance. Reduced cerebral blood flow and clinical risk factors did not predict the need for carotid shunting (P > 0.1). Multiple logistic regression analysis showed that reduced cerebrovascular reserve was the only reliable predictor of the need for carotid shunting (P < 0.01). When a severely reduced cerebrovascular reserve (8/8) or reduced cerebral blood flow and cerebrovascular reserve with contralateral carotid stenosis (6/7) were present, carotid shunting was necessary, with positive and negative predictive values of 91% (10/11) and 94% (60/64), respectively. CONCLUSION: A reduced cerebrovascular reserve can predict the development of cerebral ischemia during carotid clamping. Acetazolamide stress brain-perfusion SPECT may be useful as a complementary method in determining selective carotid shunting during carotid endarterectomy.