Potential surrogate markers of cerebral microvascular angiopathy in asymptomatic subjects at risk of stroke

Cerebral microvascular angiopathy (MVA) is associated with clinical vascular risk factors and is characterised by histological changes, including thickening of the walls of arterial vessels and dilatation of the Virchow-Robin spaces (VRS). We have previously described two novel biomarkers of MVA based on magnetic resonance imaging (MRI), VRS dilatation and abnormalities in the transfer of systolic arterial pulsation to the ventricular CSF, which occur as a result of decreased cerebral arterial compliance. These are associated with vascular dementia and treatment-resistant late onset depression. We studied a group of normal subjects at risk of cerebrovascular disease to determine if these biomarkers are present in patients who have no evidence of symptomatic vascular disease. We studied 31 subjects, 16 with three or more vascular risk factors and 15 with one or less significant risk factors. We measured arterial blood flow and CSF flow in the cerebral aqueduct, white matter lesion load, and the distribution and number of VRS. There were significant differences in CSF pulsatility and in VRS in the basal ganglia between the two groups, but no differences in white matter lesion load. We conclude that asymptomatic subjects at risk of stroke have MRI evidence of MVA before white matter lesions become apparent.     

Prediction of Cognitive Progression in Individuals with Mild Cognitive Impairment Using Radiomics as an Improvement of the ATN System: A Five-Year Follow-Up Study

ObjectiveTo improve the N biomarker in the amyloid/tau/neurodegeneration system by radiomics and study its value for predicting cognitive progression in individuals with mild cognitive impairment (MCI).Materials and MethodsA group of 147 healthy controls (HCs) (72 male; mean age ± standard deviation, 73.7 ± 6.3 years), 197 patients with MCI (114 male; 72.2 ± 7.1 years), and 128 patients with Alzheimer’s disease (AD) (74 male; 73.7 ± 8.4 years) were included. Optimal A, T, and N biomarkers for discriminating HC and AD were selected using receiver operating characteristic (ROC) curve analysis. A radiomics model containing comprehensive information of the whole cerebral cortex and deep nuclei was established to create a new N biomarker. Cerebrospinal fluid (CSF) biomarkers were evaluated to determine the optimal A or T biomarkers. All MCI patients were followed up until AD conversion or for at least 60 months. The predictive value of A, T, and the radiomics-based N biomarker for cognitive progression of MCI to AD were analyzed using Kaplan-Meier estimates and the log-rank test.ResultsThe radiomics-based N biomarker showed an ROC curve area of 0.998 for discriminating between AD and HC. CSF Aβ42 and p-tau proteins were identified as the optimal A and T biomarkers, respectively. For MCI patients on the Alzheimer’s continuum, isolated A+ was an indicator of cognitive stability, while abnormalities of T and N, separately or simultaneously, indicated a high risk of progression. For MCI patients with suspected non-Alzheimer’s disease pathophysiology, isolated T+ indicated cognitive stability, while the appearance of the radiomics-based N+ indicated a high risk of progression to AD.ConclusionWe proposed a new radiomics-based improved N biomarker that could help identify patients with MCI who are at a higher risk for cognitive progression. In addition, we clarified the value of a single A/T/N biomarker for predicting the cognitive progression of MCI.     

脑血流灌注显像与灌注加权磁共振成像在脑缺血诊断中的对比研究

目的:通过比较脑血流灌注显像与灌注加权磁共振成像的病变检出率,探讨两种方法在诊断缺血性脑血管病中的价值。方法:将78例缺血性脑血管病患者分为单侧血管病变组和双侧血管病变组,分别对两组患者的两种检查结果进行对比分析。结果:通过比较78例患者两种显像结果发现,脑血流灌注显像及灌注加权磁共振成像的阳性检出率分别为91.03%、76.92%(P=0.016),差异有显著性。单侧血管病变组患者的脑血流灌注显像及PWI的阳性检出率分别为88.37%、79.07%(P=0.243),差异无显著性。双侧血管病变组患者的脑血流灌注显像及PWI的阳性检出率分别为94.29%、74.29%(P=0.022),差异有显著性。结论:在单侧脑血管病变组,脑血流灌注显像与PWI敏感程度相当;而在双侧脑血管病变组,脑血流灌注显像较PWI敏感。     

Longitudinal MRI shows no cerebral abnormality in chronic fatigue syndrome

MRI has previously provided conflicting results when used to search for brain abnormalities in sufferers of chronic fatigue syndrome (CFS). Eighteen CFS patients and nine healthy volunteers each underwent MRI on two occasions, one year apart. The resulting images were examined for abnormalities in brain atrophy, deep white matter hyperintensities (WMH) and cerebral blood and cerebrospinal fluid (CSF) flow. Mean proportionate CSF volume was not significantly different between subject groups. All participants showed a slight increase in CSF between scans, but no significant difference was found between those with CFS and those without. Between-group comparisons of ventricular volume revealed no significant differences at study commencement and no significant change over the year. No significant inter-group differences were found for any of the cerebral blood and CSF flow parameters. Low levels of WMH were found in all participants. Objective scoring of WMH using Scheltens'' scale revealed no change in summary components (prosencephalic deep white matter hyperintensities, basal ganglia hyperintensities and infratentorial hyperintensities) or in individual component variables between the baseline and 1 year follow-up scans. No abnormal patterns in rate and extent of brain atrophy, ventricle volume, white matter lesions, cerebral blood flow or aqueductal CSF flow were detected in the CFS population. These results throw open the debate into whether MRI scanning can reveal diagnostic signs of CFS and clinically questions the diagnoses of CFS made on the basis of previous research conclusions.Chronic fatigue syndrome (CFS) is a symptom-based illness that lacks definitive biological markers. No precise underlying causes have been identified but extensive studies which have identified a variety of predisposing or initiating factors, which include infectious agents, genetic susceptibilities, immune system abnormalities and psychiatric disorders. Many of the typical symptoms, such as impaired short-term memory and concentration, headaches and altered sleep patterns, have led researchers to look for abnormalities within the central nervous system (CNS). Previous studies using cerebral MRI have led to conflicting reports. Abnormalities described by some researchers include a significant increase in small white matter hyperintensities (WMH) in the frontal lobes (seen on T₂ weighted images) [1] and increased ventricular volume [2], but other researchers have failed to find significant differences in WMH between CFS patients and control subjects [3, 4]. Studies of cerebral blood flow using single photon computed tomography (SPECT) have also produced contradictory results, with an increase in CNS perfusion abnormalities in CFS patients reported in some studies [5, 6] but other studies failing to identify significant differences [7]. The conflicting results may be due to variations in patient selection and study design.We report the first longitudinal study of cerebral MRI in patients selected using rigorous criteria for CFS. The study was undertaken as part of a larger study examining the effectiveness of an osteopathic treatment for CFS. The component of the study reported here was designed to detect differences in the extent or progression of cerebral atrophy, WMH, total cerebral blood flow and CSF pulsatility between CFS patients and normal controls over a period of one year.     

Multimodality MR imaging depiction of hemodynamic changes and cerebral ischemia in subarachnoid hemorrhage.

BACKGROUND AND PURPOSE: Subarachnoid hemorrhage (SAH) is a common and serious neurologic emergent condition. We tested the hypothesis that multimodality MR imaging depicts changes in cerebral blood flow SAH, before any surgical or endovascular intervention, and that the frequency of these changes increases with time after ictus. METHODS: We prospectively examined 37 patients with suspected SAH and three with symptoms of acute stroke but who subsequently had SAH. Routine CT and multimodality MR imaging were performed within 18 h of presentation. Standard MR imaging, diffusion-weighted MR imaging, time-of-flight MR angiography, and dynamic first-pass gadolinium-enhanced MR perfusion imaging were performed. Images were reviewed for abnormalities in cerebral blood flow, ischemia, and infarction. Nine patients did not have SAH at CT and CSF investigations. Of 31 patients with proved SAH, 13 were examined during the acute stage (within 4 d of ictus) and 18, during the subacute stage (4-14 d after ictus). RESULTS: MR imaging showed alteration in cerebral blood flow parameters in 16 of 31 patients before surgery or endovascular treatment. The frequency of blood flow changes and associated complications increased with worsening clinical grade and increasing time after ictus. CONCLUSION: Multimodality MR imaging provides information not available from CT in patients with SAH. MR imaging shows oligemic and ischemic areas in SAH before surgery or endovascular treatment. MR imaging is a simple noninvasive method of assessing cerebral blood flow and its complications in SAH. It can be performed in a clinical environment.     

Relationship between cerebrospinal fluid and blood dynamics in healthy volunteers and patients with communicating hydrocephalus

RATIONALE AND OBJECTIVES: Using magnetic resonance imaging (MRI), we investigated cerebral blood and cerebrospinal fluid (CSF) flows in patients with communicating hydrocephalus (CH) and in healthy volunteers to determine the contribution of CSF flow to brain pressure regulation in CH patients. METHODS: Cine phase-contrast MRI data from 16 healthy volunteers and 12 patients with CH characterized by hyperdynamic aqueductal CSF flow were analyzed using in-house image-processing software that automatically measured flow curves. Amplitude and temporal CSF and blood flow parameters were compared in the 2 groups. RESULTS: Jugular peak flow occurred significantly earlier (P < 0.01) in the CH patients than in the healthy volunteers. Cervical CSF oscillations were not significantly different between the 2 groups. CONCLUSION: Venous vessel compression and/or changes in intracranial subarachnoid CSF flow produce an increase in ventricular CSF flush that compensates for vascular brain expansion in patients with CH.     

99mTc-HMPAO SPECT study of cerebral perfusion after treatment with medication and electroconvulsive therapy in major depression.

Compromised regional cerebral blood flow (rCBF) in major depressive disorder may be partly reversed by successful antidepressant treatment. However, it is not known if the reversal of rCBF compromise is dependent on the mode of antidepressant treatment. The current study aimed to address this question. METHODS: Thirty-three patients (19 women and 14 men; mean age +/- SD, 53 +/- 16 y) with moderate major depressive disorder were studied before 6 wk of treatment with tricyclic antidepressants, selective serotonin reuptake inhibitors, or a course of electroconvulsive therapy, and 31 of these patients were also studied afterward. A comparison group of 25 healthy volunteers (13 women and 12 men; mean age, 49 +/- 15 y) were studied once. rCBF was assessed using 99mTc-hexamethylpropyleneamine oxime SPECT. Images were analyzed using globally normalized statistical parametric mapping localized to the Montreal Neurologic Institute brain atlas. RESULTS: Baseline rCBF was lower in depressed patients than in controls in the frontal cortex and subcortical nuclei bilaterally. A response to medication was associated with normalization of rCBF deficits, whereas a response to electroconvulsive therapy was associated with an additional rCBF decrease in the parietotemporal and cerebellar regions bilaterally. CONCLUSION: Hypoperfusion in major depressive disorder largely normalizes after a response to pharmacotherapy. Perfusion changes after a response to electroconvulsive therapy may follow a different course.     

SPECT imaging in head injury interpreted with statistical parametric mapping.

This study investigated regional cerebral blood flow in head-injured patients using statistical parametric mapping (SPM) to detect hypoperfusion on (99m)Tc-hexamethylpropyleneamine oxime (HMPAO) SPECT scans. METHODS: Acute and follow-up SPECT and MRI scans from 61 patients who were admitted to a regional neurosurgical unit were examined. Patients had acute MRI and SPECT at 2-18 d after injury and on follow-up between 130 and 366 d after injury. Thirty-two scans from non-head-injured patients were used as a SPECT control group. The SPECT images were first aligned to the Talairach-Tournoux atlas and then analyzed statistically with SPM. RESULTS: SPECT detected more extensive abnormality than MRI in acute and follow-up stages. This effect was more pronounced on follow-up of patients with diffuse injury. Examination of a focal injury group indicated the involvement of frontal and temporal lobes and the anterior cingulate. Blood flow abnormalities persist, to a lesser extent, on follow-up scans. The diffuse group displayed low blood flow in the frontal and temporal lobes, including cingulate involvement, which persists at follow-up with additional involvement of the thalamus. CONCLUSION: SPM has a role in SPECT image interpretation because it allows better visualization than other methods of quantitative analysis of the spatial distribution of abnormalities in focal and diffuse head injury. Frontal lobe blood flow abnormality (particularly anterofrontal regions and mesiofrontal areas) is common after head injury.     

Postoperative fluid-attenuated inversion recovery MR imaging of cerebral gliomas: initial results

Fluid-attenuated inversion-recovery (FLAIR) imaging has shown to be a valuable imaging modality in the assessment of intra-axial brain tumors; however, no data are available about the role of this technique in the clinically important postoperative stage. The purpose of this study was to evaluate the diagnostic potential of FLAIR MR imaging in residual tumor after surgical resection of cerebral gliomas. Fifteen patients with residual cerebral gliomas were examined within the first 18 days after partial surgical resection of cerebral gliomas. The imaging protocol included T1-weighted spin echo, T2- and proton-density-weighted fast spin echo, and FLAIR imaging with identical slice parameters. T1 and FLAIR were repeated after contrast media application. Detection and delineation of residual tumor were the primary parameters of the image analysis. Additionally, the influence of image artifacts on the image interpretation was assessed. On FLAIR images residual signal abnormalities at the border of the resection cavities were observed in all patients, whereas T2- and T1-weighted images present residual abnormalities in 13 of 15 and 10 of 15 patients, respectively. The FLAIR imaging was found to be superior to conventional imaging sequences in the delineation of these changes and comparable to contrast enhanced T1-weighted imaging in the delineation of residual enhancing lesions. Because of protein cell components and blood byproducts within the resection cavity, FLAIR imaging was unable to suppress the cerebrospinal fluid (CSF) in 4 patients. After the decomposition of proteins and blood, CSF could again be completely suppressed and residual or recurrent tumors were clearly identified. Our preliminary study has shown that FLAIR may be a valuable diagnostic modality in the early postoperative MR imaging after resection of cerebral gliomas due to its better delineation of residual pathologic signal at the border of the resection cavity. It should therefore be integrated into the early and/or intraoperative MR imaging protocol.     

A technetium-99m hexamethylpropylene amine oxime brain single-photon emission tomography study in adolescent patients with major depressive disorder

We have not encountered any brain single-photon emission tomography (SPET) study performed in adolescent depressed patients in the literature. Therefore, we used technetium-99m hexamethylpropylene amine oxime (^99mTc-HMPAO) brain SPET in adolescent patients with major depressive disorder (MDD) to examine the possible changes in cerebral perfusion and the possible association between perfusion indices and clinical variables. Fourteen adolescent out-patients (nine females, five males; mean±SD age: 13.11±1.43 years; range: 11–15 years) fulfilling the DSM-IV criteria for MDD and 11 age-matched healthy control subjects (six females, five males; mean±SD age: 13.80±1.60 years; range: 12–15 years) were included in the study. ⁹⁹Tc-HMPAO brain SPET was performed twice in the patient group and once in the control group. The first SPET investigation was performed under non-medicated conditions and the second was performed after depressive symptoms had subsided. A relative perfusion index (PI) was calculated as the ratio of regional cortical activity to the whole brain activity. We found significant differences between the PI values of the untreated depressed patients and those of the controls, indicating relatively reduced perfusion in the left anterofrontal and left temporal cortical areas. No significant differences in regional PI values were found between the remitted depressed patients and the controls. Our study suggests that adolescent patients with MDD may have regional cerebral blood flow deficits in frontal regions and a greater anterofrontal right-left perfusion asymmetry compared with normal subjects. The fact that these abnormalities in perfusion indices have a trend toward normal values with symptomatic improvement suggests that they may be state-dependent markers for adolescent MDD. Received 11 January and in revised form 11 February 1998     

Assessment of CSF dynamics and venous flow in the superior sagittal sinus by MRI in idiopathic intracranial hypertension: a preliminary study

A velocity-sensitive magnetic resonance imaging (MRI) phase-mapping method was used for noninvasive study of cerebrospinal fluid (CSF) flow in the cerebral aqueduct, for indirect calculation of supra-tentorial CSF production, and for measurement of blood flow in the superoor sagittal sinus (SSS). We examined 12 patients with idiopathic intracranial hypertension (HH; pseudotumour cerebri), and 10 healthy volunteers. The peak caudal and rostal CSF flow in the aqueduct during the cardiac cycle did not differ significantly between the patients and the volunteers. A significant correlation was found between the CSF volume flow amplitude and the resistance to cerebrospinal fluid out-flow in the patients (p<0.05). The calculated mean supratentorial CSF production rate was 0.79 ml/min in the patients and 0.70 ml/min in the controls, but this difference was not statistically significant. However, the MRI measurements suggested CSF hypersecretion in three patients, whereas increased transependymal passage of CSF could have been the cause of negative calculated CSF production rates in two others. A tendency towards lower mean blood flow in the SSS (mean 345 ml/min) in the patients than in the controls (mean 457 ml/min) was found, and in two patients showed very low values. We showed that MRI phase-mapping may be used to study the relative importance of the pathophysiological factors thought to play a role in the development of IIH.     

Statistical image analysis of cerebral blood flow in vascular dementia with small-vessel disease.

Small-vessel disease with dementia, which is the most frequent type of vascular dementia (VaD), often shows a cerebral blood flow (CBF) distribution with no obvious focal abnormalities and is therefore difficult to evaluate objectively. In this study, we combined CBF SPECT with 3-dimensional fractal analysis (3D-FA) to quantitatively assess the heterogeneity of CBF distribution and with 3-dimensional stereotactic surface projections (3D-SSP) to evaluate the distribution of CBF. We then evaluated the clinical validity of these techniques for the imaging diagnosis of VaD. METHODS: The subjects consisted of 17 patients who were diagnosed as having VaD due to small-vessel disease (VaD group) on the basis of a full clinical examination, including history, neuropsychologic tests, neurologic examination, and neuroimaging methods, and 20 healthy volunteers (control group). CBF SPECT was performed with (99m)Tc-hexamethylpropyleneamine oxime, and the reconstructed images were subjected to image processing by 3D-FA and 3D-SSP. Based on the results, the fractal dimension (FD) was compared between the VaD and control groups, and the distribution pattern of CBF was examined in the VaD group. RESULTS: The mean FD values in the VaD group and the control group were 1.093 +/- 0.153 and 0.853 +/- 0.062 (mean +/- SD), respectively. The mean FD value in the VaD group was significantly higher than that in the control group (P < 0.0001). 3D-SSP analysis in the VaD group showed that there were 2 abnormal patterns: One was globally reduced blood flow in the whole cerebral cortex, and the other was a reduction mainly confined to the frontal region. CONCLUSION: CBF SPECT images showed higher mean FD values in the VaD group than in the control group, suggesting a difference in the heterogeneity of CBF. Image processing with 3D-SSP successfully revealed that reduced cortical blood flow could be divided into 2 patterns. Because image analysis techniques, such as 3D-FA and 3D-SSP, allowed the simple and objective evaluation of CBF in patients with VaD, these methods seem to be useful for detailed examination of the blood flow pattern detected by CBF SPECT in patients with VaD.     

Regional cerebral blood flow in patients with mild hypothyroidism.

Emotional and cognitive abnormalities are common in adult hypothyroidism. Few studies, however, have evaluated cerebral perfusion and metabolism in this disorder. The aims of this study were to compare regional cerebral blood flow (rCBF) between hypothyroid patients and healthy subjects and assess flow during the euthyroid state after treatment. METHODS: Ten mildly hypothyroid patients, before and after thyroxine treatment, and 10 healthy controls underwent 99mTc-hexamethylpropyleneamine oxime brain SPECT, MRI, and psychometric testing. SPECT images were analyzed using statistical parametric mapping. RESULTS: Compared with controls, rCBF in patients before treatment was lower in right parietooccipital gyri, cuneus, posterior cingulate, lingual gyrus, fusiform, insula, and pre- and postcentral gyri. Perfusion did not normalize on a return to the euthyroid state. CONCLUSION: Decreased rCBF in mild hypothyroidism is found in regions mediating attention, motor speed, memory, and visuospatial processing, faculties affected in hypothyroidism. Follow-up studies are needed to determine the longer-term persistence of perfusion abnormalities in this disorder.     

Evaluating the Effect of Arterial Pulsation on Cerebrospinal Fluid Motion in the Sylvian Fissure of Patients with Middle Cerebral Artery Occlusion Using Low b-value Diffusion-weighted Imaging

PurposeDecrease in signal of the cerebrospinal fluid (CSF) on low b-value diffusion weighted image (DWI) due to non-uniform flow can provide additional information regarding CSF motion. The purpose of the current study was to evaluate whether arterial pulsations constitute the driving force of CSF motion.MethodsWe evaluated the CSF signals within the Sylvian fissure on low b-value DWI in 19 patients with unilateral middle cerebral artery (MCA) occlusion. DWI with b-value of 500 s/mm² was evaluated for a decrease in CSF signal within the Sylvian fissure including the Sylvian vallecula and lower, middle, and higher Sylvian fissures and graded as follows: the same as contralateral side; smaller signal decrease than that on contralateral side; and no signal decrease. MR angiography (MRA) findings of MCA were graded as follows: the same as contralateral, lower signal than contralateral signal, and no signal. In 15 patients, regional cerebral blood flow (rCBF) was evaluated using single-photon emission computed tomography (SPECT) studies and graded as > 90%, 90%–70%, and < 70% rCBF compared to contralateral. The correlations between the gradings were evaluated using G likelihood-ratio test.ResultsThere was no statistically significant correlation between the MRA and low b-value DWI gradings of CSF in all areas. There were statistically significant correlations between the decreases in CBF on SPECT and CSF signals in the middle Sylvian fissure.ConclusionThe driving force of CSF pulsation in the Sylvian sinus may be related to the pulsations of the cerebral hemisphere rather than direct arterial pulsations.     

Quantitative estimation of brain atrophy and function with PET and MRI two-dimensional projection images]

PURPOSE: The purpose of this paper is to estimate the extent of atrophy and the decline in brain function objectively and quantitatively. METHODS: Two-dimensional (2D) projection images of three-dimensional (3D) transaxial images of positron emission tomography (PET) and magnetic resonance imaging (MRI) were made by means of the Mollweide method which keeps the area of the brain surface. A correlation image was generated between 2D projection images of MRI and cerebral blood flow (CBF) or 18F-fluorodeoxyglucose (FDG) PET images and the sulcus was extracted from the correlation image clustered by K-means method. Furthermore, the extent of atrophy was evaluated from the extracted sulcus on 2D-projection MRI and the cerebral cortical function such as blood flow or glucose metabolic rate was assessed in the cortex excluding sulcus on 2D-projection PET image, and then the relationship between the cerebral atrophy and function was evaluated. This method was applied to the two groups, the young and the aged normal subjects, and the relationship between the age and the rate of atrophy or the cerebral blood flow was investigated. This method was also applied to FDG-PET and MRI studies in the normal controls and in patients with corticobasal degeneration. RESULTS: The mean rate of atrophy in the aged group was found to be higher than that in the young. The mean value and the variance of the cerebral blood flow for the young are greater than those of the aged. The sulci were similarly extracted using either CBF or FDG PET images. CONCLUSIONS: The purposed method using 2-D projection images of MRI and PET is clinically useful for quantitative assessment of atrophic change and functional disorder of cerebral cortex.     

低剂量双源CT颅脑灌注成像在超急性期脑梗死中的诊断价值

目的探讨管电压为70 kV时不同管电流及采集频次对双源CT颅脑灌注成像(CTP)图像质量、辐射剂量的影响,及其在超急性期脑梗死患者中的诊断价值。方法前瞻性选取2017年12月至2019年2月浙江省丽水市中心医院临床可疑的超急性期脑梗死患者190例,按照数字表法随机分为4组,A、B、C组均50例,D组40例,均在发病6 h内行双源CT平扫及70 kV管电压颅脑灌注成像。A组管电流120 mA,B组和C组管电流均为100 mA,D组管电流80 mA。A、B、D组采集频次21次,C组采集频次17次。测量脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)、达峰时间(TTP)等,评价图像质量,记录有效剂量(ED)。各参数组间图像质量及辐射剂量的比较采用单因素方差分析。结果4组CTP伪彩图灰质和白质灌注参数(CBF、CBV、MTT及TTP)的差异均无统计学意义(P>0.05),所有图像均可满足诊断要求。A组颈内动脉、大脑中动脉血管管腔边缘锐利度、整体图像质量及颈内动脉图像噪声评级高于D组(P<0.05);A组颈内动脉血管管腔边缘锐利度高于B、C组(P<0.05);B、C组颈内动脉及大脑中动脉血管管腔边缘锐利度均高于D组(P<0.05)。CT平扫及A、B、C、D组的ED分别为1.10、2.11、1.76、1.42、1.40 mSv,差异有统计学意义(P<0.05)。与A组相比,B、C及D组的ED均有不同程度的降低,分别降低16.6%(0.35/2.11)、32.7%(0.69/2.11)及33.6%(0.71/2.11),差异均有统计学意义(P均<0.05)。对于超急性期脑梗死,低剂量双源CTP阳性率为93.5%(172/184),CT平扫阳性率为52.2%(96/184);对于超急性期腔隙性脑梗死,低剂量双源CTP阳性率为72.1%(31/43),CT平扫阳性率为16.3%(7/43)。结论70 kV管电压CTP,适当减低管电流(100 mA)及采集频次(17次)可降低辐射剂量且图像质量可满足诊断需求。相较于CT平扫,低剂量双源CTP对于超急性期脑梗死尤其是腔隙性脑梗死更为敏感。     

Differences in resting state regional cerebral blood flow assessed with 99mTc-HMPAO SPECT and brain atlas matching between depressed patients with and without tinnitus

An increased occurrence of major depressive disorder has been reported in tinnitus patients, and of tinnitus in depressive patients. Involvement of several Brodmann areas (BAs) has been reported in tinnitus perception. The aim of this study was to assess the regional cerebral blood flow (rCBF) changes in depressed patients with and without tinnitus. The rCBF distribution at rest was compared among 45 patients with a lifetime prevalence of major depressive disorder, of whom 27 had severe tinnitus, and 26 normal healthy subjects. 99mTc-hexamethylenepropylene amine oxime (99mTc-HMPAO) single photon emission computed tomography (SPECT), using a three-headed gamma camera, was performed and the uptake in 34 functional sub-volumes of the brain bilaterally was assessed by a computerized brain atlas. Decreased rCBF in right frontal lobe BA 45 (P<0.05), the left parietal lobe BA 39 (P<0.00) and the left visual association cortex BA 18 (P<0.05) was found in tinnitus patients compared with non-tinnitus patients. The proportion of tinnitus patients with pronounced rCBF alterations in one or more of the temporal lobe BAs 41+21+22 was increased compared to gender matched controls (P<0.00) and patients without tinnitus (P<0.05). Positive correlations were found between trait anxiety scales from the Karolinska Scales of Personality and rCBF in tinnitus patients only in three limbic BAs (P<0.01), and inverse correlations in non-tinnitus patients only in five BAs subserving auditory perception and processing (P<0.05). rCBF differences between healthy controls and depressed patients with and without tinnitus were found in this study. The rCBF alterations were distributed in the cortex and were particularly specific in the auditory cortex. These findings suggest that taking audiological symptoms into account may yield more consistent results between rCBF studies of depression.     

Changes in the rCBF images of patients with Alzheimer's disease receiving Donepezil therapy

Alzheimer's disease is associated with a loss in presynaptic cholinergic function. It has been suggested that cholinergic inhibitors such as donepezil hydrochloride (Donepezil) could restore this function and improve some of the symptoms of Alzheimer's disease. Previous work has shown that Donepezil improves cognitive and global function in patients with mild to moderate Alzheimer's disease. This study reviewed retrospectively 12 patients who had previously had a 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) single photon emission tomography (SPET) regional cerebral blood flow (rCBF) examination and had gone on to receive Donepezil therapy. These patients were recalled for a further 99Tcm-HMPAO SPET rCBF examination and the image data sets were compared. The results showed an overall increase in global cerebral blood flow (P = 0.04) averaged over the group with a percentage change in blood flow ranging from -1.8% to 6.4%. However, some patients showed a slight decrease in blood flow. When the data were analysed in terms of regional cerebral blood flow, we found that the most significant increase in blood flow occurred in the frontal lobes (P = 0.02).     

Regional CBF changes in Parkinson’s disease: a correlation with motor dysfunction

Purpose The purpose of this study was to further localize cerebral perfusion abnormalities, and to better correlate these abnormalities with the clinical severity of Parkinson’s disease (PD). Methods A single-photon emission computed tomography (SPECT) study was performed on 27 patients with PD and 24 age-matched controls. SPECT images were spatially normalized, concatenated, and then decomposed using Infomax independent component analysis (ICA). The resulting image components were separated by logistic regression into two subspaces: “disease-related” components whose subject weights differed between groups, and “disease-unrelated” components. The resultant regional cerebral blood flow (rCBF) subspace images were normalized to global CBF for each subject, and then processed using statistical parametric mapping to compare rCBF values between PD and control subjects. Results In the disease-related image subspace, patients with PD exhibited significantly higher adjusted rCBF in the putamen, globus pallidum, thalamus, brainstem, and the anterior lobe of the cerebellum, and significant hypoperfusion in the parieto-temporo-occipital cortex, the dorsolateral prefrontal cortex, the insula, and the cingulate gyrus. The motor Unified Parkinson’s Disease Rating Scale scores correlated negatively with rCBF in the insula and cingulate gyrus. In the disease-unrelated image subspace, no brain voxels exhibited a significant group difference. Conclusion ICA-based separation of normalized images into disease-related and disease-unrelated subspaces revealed many disease-related group blood flow differences. The regions revealed by ICA are consistent with the current model of PD. These rCBF changes in PD have not been fully demonstrated in any single functional imaging study previously. An editorial commentary on this paper is available at     

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.