Cerebral Blood Flow Studies Research Articles

Intracranial Vasculopathy in a Patient with Systemic Sclerosis: Atherosclerotic or Moyamoya-Like Disease?

Intracranial Vasculopathy in a Patient with Systemic Sclerosis: Atherosclerotic or Moyamoya-Like Disease?

Robust method for 3D arterial spin labeling in mice

Arterial spin labeling is a versatile perfusion quantification methodology, which has the potential to provide accurate characterization of cerebral blood flow (CBF) in mouse models. However, a paucity of physiological data needed for accurate modeling, more stringent requirements for gradient performance, and strong artifacts introduced by magnetization transfer present special challenges for accurate CBF mapping in the mouse. This article describes robust mapping of CBF over three-dimensional brain regions using amplitude-modulated continuous arterial spin labeling. To provide physiological data for CBF modeling, the carotid artery blood velocity distribution was characterized using pulsed-wave Doppler ultrasound. These blood velocity measurements were used in simulations that optimize inversion efficiency for parameters meeting MRI gradient duty cycle constraints. A rapid slice positioning algorithm was developed and evaluated to provide accurate positioning of the labeling plane. To account for enhancement of T(1) due to magnetization transfer, a binary spin bath model of magnetization transfer was used to provide a more accurate estimate of CBF. Finally, a study of CBF was conducted on 10 mice with findings of highly reproducible inversion efficiency (mean ± standard-error-of-the-mean, 0.67 ± 0.03), statistically significant variation in CBF over 12 brain regions (P < 0.0001) and a mean ± standard-error-of-the-mean whole brain CBF of 219 ± 6 mL/100 g/min.

Protective effect of fruits of Morinda citrifolia L. on scopolamine induced memory impairment in mice: A behavioral, biochemical and cerebral blood flow study

Ethnopharmacological relsevanceNoni (Morinda citrifolia L.) is widely used for different illnesses including CNS disorders. Recently Noni has been reported to prevent amyloid beta induced memory impairment in mice. However, the influence of Noni on cholinergic system has not been explored so far. Therefore, present study was designed to investigate effect of Noni fruit on memory, cerebral blood flow (CBF), oxidative stress and acetylcholinesterase (AChE) activity in scopolamine induced amnesia model. Materials and methodsMice were orally treated with ethanolic extract of Noni fruit and chloroform, ethyl acetate and butanol fractions of ethanolic extract for three days. Scopolamine was administered 5min prior to acquisition trial and memory function was evaluated by passive avoidance test. CBF was measured by laser doppler flowmetry. AChE activity and oxidative stress parameters were estimated in mice brain at the end of behavioral studies. Further, effect of ethanolic extract and its fractions (5–400μg/ml) on AChE activity was measured in vitro. ResultsScopolamine caused memory impairment along with reduced CBF, increased AChE activity and oxidative stress in mice brain. Ethanolic extract of Noni fruits and its chloroform and ethyl acetate fractions significantly improved memory and CBF. However, butanol fraction had no effect. Further, increased oxidative stress and AChE activity following scopolamine was significantly attenuated by ethanolic extract of Noni and its fractions. Moreover ethanolic extract and its fractions showed dose dependent inhibition of AChE activity in vitro. ConclusionThese observations suggest that Noni may be useful in memory impairment due to its effect on CBF, AChE and oxidative stress.

Alteration of Ictal and Interictal Perfusion in Patients with Paroxysmal Kinesigenic Dyskinesia

Although previous cerebral blood flow studies have suggested that the basal ganglia or thalamus are involved in the pathogenesis of paroxysmal kinesigenic dyskinesia (PKD), the precise anatomic substrate or pathophysiological networks associated with PKD remain unclear. Here, ictal and interictal single photon emission computed tomography (SPECT) in 2 patients with idiopathic PKD compared to 6 age-matched normal controls and the perfusion findings of subtraction ictal SPECT co-registered to MRI (SISCOM) in 1 patient are reported. The interictal and ictal perfusion changes were different in each of the patients and there were no consistent anatomic substrates observed. 2 patients had significant perfusion changes in the left frontal/temporal cortices compared to controls, whereas the others showed an increased uptake of 99mTc-ethyl cysteinate dimer (ECD) in the left occipital area on subtraction SPECT imaging. The results of this study suggest that the pathophysiology of PKD cannot be simply explained by lesions of the basal ganglia or thalamus, and that other associated areas of the cortex are likely involved in these movement disorders.

Cerebral oxygen metabolism in patients with early Parkinson's disease

Aim Decreased activity of the mitochondrial electron transport chain (ETC) has been implicated in the pathogenesis of Parkinson's disease (PD). This model would most likely predict a decrease in the rate of cerebral oxygen consumption (CMRO 2). To test this hypothesis, we compared CMRO 2 and cerebral blood flow (CBF) PET scans from PD patients and healthy controls. Materials and methods Nine early-stage PD patients and 15 healthy age-matched controls underwent PET scans for quantitative mapping of CMRO 2 and CBF. Between-group differences were evaluated for absolute data and intensity-normalized values. Results No group differences were detected in regional magnitudes of CMRO 2 or CBF. Upon normalization using the reference cluster method, significant relative CMRO 2 decreases were evident in widespread prefrontal, parieto-occipital, and lateral temporal regions. Sensory-motor and subcortical regions, brainstem, and the cerebellum were spared. A similar pattern was evident in normalized CBF data, as described previously. Conclusion While the data did not reveal substantially altered absolute CMRO 2 in brain of PD patients, employing data-driven intensity normalization revealed widespread relative CMRO 2 decreases in cerebral cortex. The detected pattern was very similar to that reported in earlier CBF and CMRglc studies of PD, and in the CBF images from the same subjects. Thus, the present results are consistent with the occurrence of parallel declines in CMRO 2, CBF, and CMRglc in spatially contiguous cortical regions in early PD, and support the hypothesis that ETC dysfunction could be a primary pathogenic mechanism in early PD.

25. P300 and cerebral blood flow study in Parkinson disease and vascular parkinsonism

25. P300 and cerebral blood flow study in Parkinson disease and vascular parkinsonism

Cerebral Artery Dilatation Maintains Cerebral Oxygenation at Extreme Altitude and in Acute Hypoxia—An Ultrasound and MRI Study

Transcranial Doppler is a widely used noninvasive technique for assessing cerebral artery blood flow. All previous high altitude studies assessing cerebral blood flow (CBF) in the field that have used Doppler to measure arterial blood velocity have assumed vessel diameter to not alter. Here, we report two studies that demonstrate this is not the case. First, we report the highest recorded study of CBF (7,950 m on Everest) and demonstrate that above 5,300 m, middle cerebral artery (MCA) diameter increases (n=24 at 5,300 m, 14 at 6,400 m, and 5 at 7,950 m). Mean MCA diameter at sea level was 5.30 mm, at 5,300 m was 5.23 mm, at 6,400 m was 6.66 mm, and at 7,950 m was 9.34 mm (P<0.001 for change between 5,300 and 7,950 m). The dilatation at 7,950 m reversed with oxygen. Second, we confirm this dilatation by demonstrating the same effect (and correlating it with ultrasound) during hypoxia (FiO2=12% for 3 hours) in a 3-T magnetic resonance imaging study at sea level (n=7). From these results, we conclude that it cannot be assumed that cerebral artery diameter is constant, especially during alterations of inspired oxygen partial pressure, and that transcranial 2D ultrasound is a technique that can be used at the bedside or in the remote setting to assess MCA caliber.

Cerebrovascular response in children following severe traumatic brain injury

To describe the pathophysiologic response in cerebral blood flow (CBF) and autoregulation after severe traumatic brain injury (TBI), Glasgow Coma Score (GCS) ≤8 on admission, in children, defining a baseline for future studies. Retrospective chart review of 95 patients following TBI, ages 0.1-18.4 years (<5 years (n = 44), <2 years (n = 17)) for CBF using Xenon Computerized Tomography (XeCT) over a 10-year period and 6-month Glasgow Outcome Scores (GOS). A total of 140 CBF studies were performed variably from admission up to post injury day (PID) 9; 27 patients underwent repeat CBF study after PaCO(2) was manipulated to determine CO(2) vasoreactivity (CO(2)VR). Mean CBF on admission (PID 0, n = 26) was 32.05 ± 21.45 ml/100 g/min (mean ± SEM) and was ≤20 ml/100 g/min in eight patients. At PID 1-2, mean CBF increased to 55.36 ± 23.11 ml/100 g/min. There was significant differences in mean CBF of "favorable" outcomes (GOS ≥ 4) versus "unfavorable" outcome (GOS ≤ 3) (61.74 ± 18.27 vs. 46.54 ± 26.26, respectively (P = 0.01)). "Unfavorable" outcomes were seen in all patients with CBF ≤20 ml/100 mg/min during PID 0-2 and in 76.5% of children <2 years. CO(2)VR <2%/Torr PaCO(2) within PID 0-2 was significantly associated with "unfavorable" outcome (P = 0.029). Younger age, early or later low CBF, and CO(2)VR <2%/Torr PaCO(2) were correlated with poorer outcomes in children. This represents the largest experience with XeCT CBF in children and confirms our preliminary report of low early CBF after TBI in children, disturbed CO(2)VR, and relationship of low CBF and unfavorable outcome.

Proposal for a New Grading of Moyamoya Disease in Adult Patients

Background: Moyamoya disease (MMD) is graded based on digital subtraction angiography (DSA) with limited clinical applications. The aim was to identify clinically relevant parameters that may be used to develop a novel MMD grading system. Methods: In 40 MMD patients bilateral revascularization surgery was performed. Clinical data including DSA, MRI and regional cerebral blood flow studies were assessed. χ² test corrected for dependency of measurements at the same subject and analysis of receiver operating characteristics were used to identify key parameters. Grading system included: DSA (stenosis/occlusion = 1 point; stenosis/occlusion + intracranial compensation = 2 points; stenosis/occlusion + intracranial compensation + extra-intracranial compensation = 3 points), MRI (no sign of ischemia = 0 points; signs of ischemia = 1 point) and cerebrovascular reserve capacity (CVRC > –5% = 0 points; CVRC < –5% = 2 points). MMD grade I referred to 1–2 points, grade II to 3–4 and grade III to 5–6 points. Results: DSA, MRI and CVRC were dependent factors associated with the occurrence of clinical symptoms. Receiver operating characteristics analysis indentified the grading system as superior to each single parameter in predicting clinical symptoms. Fourteen hemispheres were graded as mild (grade I), 35 as moderate (grade II) and 31 as severe (grade III); 21% of grade I, 63% of grade II and 93% of grade III hemispheres were clinically symptomatic. Conclusions: The proposed grading system allows to stratify for clinical symptomatology in MMD patients. Future studies will have to investigate its value for assessing clinical symptoms and treatment risks.

Optically quantified cerebral blood flow

In vivo imaging allows detailed studies of cerebral blood flow and brain metabolism in both normal and pathological states. Since the 1980s, several methods to measure tissue perfusion in the brain have been introduced. Magnetic resonance imaging (MRI) techniques such as blood oxygen level dependent MRI (BOLD MRI) (Sorensen et al, 1995) and arterial spin labeling (Buxton and Frank 1997) as well as micro-positron emission tomography (Heiss et al, 1994) have enabled noninvasive chronic imaging of both regional blood flow changes and absolute perfusion in both humans and animal models. These methods, however, suffer from poor spatial resolution and are mainly useful when studying regional blood flow in the brain. Intrinsic optical imaging (Ts'o et al, 1990) enables higher spatial resolution mapping of changes in blood volume. Laser Doppler spectroscopy (Eyre et al, 1988) enables measurement of relative changes in blood flow speeds averaged over ∼1-mm2 cortical areas, while laser speckle contrast imaging (Boas and Dunn, 2010) enables these relative blood flow changes to be imaged with a spatial resolution of <100 μm. None of these optical techniques, however, can accurately resolve changes in flow in individual microvessels or determine the absolute perfusion of cortical tissue. When absolute speed measurement of individual vessels is required, two-photon excited fluorescence (2PEF) microscopy has been the tool of choice (Schaffer et al, 2006). It is, however, limited to measurement of flow speed in vessels that are oriented parallel to the imaging plane, and measurements need to be made one vessel at a time, which is a time-consuming process. Currently lacking is an imaging technique that enables absolute blood flow speed measurements in multiple individual vessels at once. In this issue of JCBFM, Srinivasan et al (2011) introduce the use of Doppler optical coherence tomography (DOCT) (Chen et al, 1997) to fill this gap. Srinivasan et al demonstrated DOCT as a viable technique to quantify blood flow across many individual vessels simultaneously in the brain of live, anesthetized rodents. Doppler optical coherence tomography measures the Doppler shift of light scattered off from moving red blood cells to quantify flow speeds, with three-dimensional spatial resolution obtained from the use of coherence tomography to isolate the signal from a single axial location and laser scanning to map the two lateral dimensions. Using this tool, absolute blood flow velocity can be rapidly determined in blood vessels that contain an axial projection. In their article, Srinivasan et al demonstrated that DOCT measurements of flow speed and vessel cross-sectional area showed conservation of volumetric flow along non-branching and branching vascular segments, confirming the quantitative accuracy of the method. They further demonstrated that DOCT enables straightforward measurement of blood flow speed in penetrating arterioles and ascending venules (the vessels most difficult to characterize with 2PEF), with all these vessels being within an ∼1-mm2 field of view measured in an ∼1-min-long scan (as opposed to 2PEF, which allows measurement of only one vessel every few minutes). To obtain a quantitative estimate of tissue perfusion, the authors summed the volumetric flow from all ascending venules in a patch of cortex and estimated the cortical volume that is served by these vessels. They found strong correlation between this DOCT measurement of tissue perfusion and the values obtained from a standard hydrogen clearance method (von Kummer et al, 1986). The DOCT measurements, however, consistently yielded higher values for tissue perfusion, likely reflecting depressed blood flow due to tissue damage from the electrode used for hydrogen clearance measurements. The DOCT technique was best suited to measurements in the top 150 μm of the brain and in larger blood vessels rather than in capillaries, and the technique is optimal for flow speeds between ∼0.5 and 10 mm/s with current DOCT systems. Overall, the approach of summing the volumetric flow measured by DOCT of all the ascending venules in a patch of cortex appears to provide a robust tool for minimally invasive measurements of absolute brain tissue perfusion with a spatial resolution that is not matched by previous methods, opening the door to studies of how blood flow is altered at the microvascular scale by physiological and pathophysiological events in the brain.

Cerebral blood flow is reduced in chronic fatigue syndrome as assessed by arterial spin labeling

Background Chronic fatigue syndrome is diagnosed by a set of clinical criteria and therefore is probably heterogeneous. Earlier reports tested the hypothesis that the syndrome had a neurological substrate by doing studies of cerebral blood flow (CBF) but with discrepant results. One possible reason for the discrepancy was that relative CBF was assessed. We found reduced CBF in an earlier study of absolute CBF using xenon-CT. The purpose of this study was to use a second method of assessing CBF and to look within the study group for heterogeneity of responses. Method Eleven CFS patients and 10 age matched healthy controls underwent neuroimaging using arterial spin labeling to determine their regional and global absolute CBF. A template was constructed based on the control data, and individual patient montages were compared on a case by case basis to determine if differences in regions of interest occurred. Results The patients as a group had significantly lower global CBF than the controls. The reduction in CBF occurred across nearly every region assessed. Nine of the 11 patients showed these reductions compared to the average control data, while two patients showed actual increases relative to the controls. Conclusion The data extend our earlier observation that CFS patients as a group have broad decreases in CBF compared to healthy controls. However, as expected, the effect was not homogeneous in that 2 of the 11 patients studied showed actual increases in CBF relative to controls.

Comparative study of anatomical normalization errors in SPM and 3D-SSP using digital brain phantom

In single photon emission computed tomography (SPECT) cerebral blood flow studies, two major algorithms are widely used statistical parametric mapping (SPM) and three-dimensional stereotactic surface projections (3D-SSP). The aim of this study is to compare an SPM algorithm-based easy Z score imaging system (eZIS) and a 3D-SSP system in the errors of anatomical standardization using 3D-digital brain phantom images. We developed a 3D-brain digital phantom based on MR images to simulate the effects of head tilt, perfusion defective region size, and count value reduction rate on the SPECT images. This digital phantom was used to compare the errors of anatomical standardization by the eZIS and the 3D-SSP algorithms. While the eZIS allowed accurate standardization of the images of the phantom simulating a head in rotation, lateroflexion, anteflexion, or retroflexion without angle dependency, the standardization by 3D-SSP was not accurate enough at approximately 25° or more head tilt. When the simulated head contained perfusion defective regions, one of the 3D-SSP images showed an error of 6.9% from the true value. Meanwhile, one of the eZIS images showed an error as large as 63.4%, revealing a significant underestimation. When required to evaluate regions with decreased perfusion due to such causes as hemodynamic cerebral ischemia, the 3D-SSP is desirable. In a statistical image analysis, we must reconfirm the image after anatomical standardization by all means.

Intracerebral Hemorrhage and Head Trauma

Nontraumatic intracerebral hemorrhage (ICH) remains a devastating condition with 30-day mortality rates of 35% to 52%. Until the pathophysiology of this condition is better understood, it will not be possible to develop effective therapies. Studies of cerebral blood flow and metabolism in patients with acute ICH show similar abnormalities to those that occur in patients with traumatic brain injury, thus raising the question of whether there are common mechanisms of injury shared by the 2 conditions. In both ICH and traumatic brain injury, there is an early reduction in the cerebral metabolic rate of oxygen without ischemia, mitochondrial dysfunction, and transient focal increases in regional glucose metabolism that occur after a few days. ICH and traumatic brain injury share barotrauma from pressure waves that propagate through the intracranial contents as a common mechanism of brain injury. Recent data demonstrating contralateral hemispheric damage in patients with acute ICH provide further support for this theory of common injury mechanisms.

Cerebral reserve is decreased in elderly patients with carotid stenosis

Octogenarians and even patients over 70 years old have unexplained poor outcomes with carotid angioplasty and stenting (CAS). We sought to evaluate whether older patients may have compromised intracranial collaterals and cerebral reserve and be intolerant to otherwise clinically silent emboli generated during CAS. One thousand twenty-four cerebral blood flow (CBF) studies performed between 1991 and 2001 with stable xenon computed tomography scans (Xe/CT) were reviewed. CBF was measured before and after 1 gm intravenous acetazolamide (ACZ), a cerebral vasodilator. The normal response to ACZ is an increase in CBF. In areas of significant compromise of cerebral reserve (CR), CBF drops, representing a "steal" phenomenon. CBF changes were categorized as normal or abnormal and correlated with age, gender, cerebral symptoms, and with intracranial, carotid, or vertebral artery disease. Logistic regression was used to determine the effect of age on CR in the entire group and a subgroup of 179 patients with significant carotid stenosis of >50%. Nine hundred sixteen studies were suitable for analysis. Carotid occlusion was predictive of decreased reserve (OR, 3.9; P = .03) regardless of age. There was also a trend toward lower reserve with severe carotid stenosis >70% (OR, 3) and in women (OR, 1.8; P = .08). Age >or=70 had no effect on reserve in the overall heterogeneous population with and without carotid disease and neither did a history of stroke, carotid, or intracranial stenosis. However, in 179 patients with significant carotid stenosis, age >or=70 was predictive of poor reserve (OR, 2.7; P = .03) and so was the presence of peripheral vascular disease (OR, 3.7; P = .03). A trend toward decreased reserve was also seen in women (OR, 2.3; P = .08). Age >or=70 is associated with poor cerebral reserve in patients with significant carotid stenosis as measured by CBF response to an ACZ challenge. Thus, patients >or=70 may be more sensitive to minor cerebral emboli, which may be one factor explaining their higher risk of stroke during CAS.

Sensory alien hand syndrome in corticobasal degeneration: A cerebral blood flow study

The presence of alien hand syndrome (AHS) is suggestive of the diagnosis of corticobasal degeneration when it develops in a progressive way. Sensory AHS (sAHS) should be distinguished from the motor form described more commonly. The physiopathology of sAHS remains unclear. The aim of this study is to determine cerebral regions involved in sAHS. We compared perfusion single photon emission computer tomography scans of patients with sAHS (n = 3) and without (n = 4). We observed significant decrease of regional cerebral blood flow over the nondominant thalamus in sAHS+ compared to sAHS- patients. This result suggests the involvement of the nondominant thalamus in sAHS.

Prediction of Stroke Rehabilitation Outcome with Xenon-enhanced Computed Tomography Cerebral Blood Flow Study

Cerebral blood flow (CBF) of stroke patients in the chronic stage is supposed to reflect brain functions. We examined the relation between rehabilitation outcome and CBF values. The study group comprised 101 consecutive patients (mean age, 69±12 years) including 61 patients with cerebral infarction, 32 patients with cerebral hemorrhage, and 8 patients with subarachnoid hemorrhage. Xenon-enhanced computed tomography was performed on 39 days on average after stroke onset. Regions of interest were in the cerebral cortices, putamen and thalamus, and CBF values were statistically compared with the functional independence measure (FIM). Furthermore, we performed a multivariate analysis for predictive factors. 1. The right mean CBF (mCBF) tended to be more closely correlated with the FIM total scores at discharge (r=0.495, P<.001) than the left mCBF (r=0.351, P<.001), in case of significance level 0.1 and statistical power 0.65. 2. The FIM total and motor scores at discharge showed the highest correlations to regional CBF (rCBF) in the right frontal cortex, and the FIM cognitive scores at discharge showed the highest correlation to rCBF in the left frontal cortex. 3. Right cerebral infarct subgroup (n=30) showed significant correlations between FIM total scores at discharge and mCBF values of the right (r=0.582, P<.001) and the left (r=0.563, P<.005) brain, respectively. 4. Rehabilitation outcome evaluated with the FIM total scores could be led by the formulae with the factors of age, gender, NIHSS, right/left hemispheric lesions and the right mCBF values (r=0.837, P<.001). The CBF of the right brain proved to be more influencing to rehabilitation results.

Cortical hypometabolism and hypoperfusion in Parkinson’s disease is extensive: probably even at early disease stages

Recent cerebral blood flow (CBF) and glucose consumption (CMRglc) studies of Parkinson's disease (PD) revealed conflicting results. Using simulated data, we previously demonstrated that the often-reported subcortical hypermetabolism in PD could be explained as an artifact of biased global mean (GM) normalization, and that low-magnitude, extensive cortical hypometabolism is best detected by alternative data-driven normalization methods. Thus, we hypothesized that PD is characterized by extensive cortical hypometabolism but no concurrent widespread subcortical hypermetabolism and tested it on three independent samples of PD patients. We compared SPECT CBF images of 32 early-stage and 33 late-stage PD patients with that of 60 matched controls. We also compared PET FDG images from 23 late-stage PD patients with that of 13 controls. Three different normalization methods were compared: (1) GM normalization, (2) cerebellum normalization, (3) reference cluster normalization (Yakushev et al.). We employed standard voxel-based statistics (fMRIstat) and principal component analysis (SSM). Additionally, we performed a meta-analysis of all quantitative CBF and CMRglc studies in the literature to investigate whether the global mean (GM) values in PD are decreased. Voxel-based analysis with GM normalization and the SSM method performed similarly, i.e., both detected decreases in small cortical clusters and concomitant increases in extensive subcortical regions. Cerebellum normalization revealed more widespread cortical decreases but no subcortical increase. In all comparisons, the Yakushev method detected nearly identical patterns of very extensive cortical hypometabolism. Lastly, the meta-analyses demonstrated that global CBF and CMRglc values are decreased in PD. Based on the results, we conclude that PD most likely has widespread cortical hypometabolism, even at early disease stages. In contrast, extensive subcortical hypermetabolism is probably not a feature of PD.

An arterial spin labeling investigation of cerebral blood flow deficits in chronic stroke survivors

Although the acute stroke literature indicates that cerebral blood flow (CBF) may commonly be disordered in stroke survivors, limited research has investigated whether CBF remains aberrant in the chronic phase of stroke. A directed study of CBF in stroke is needed because reduced CBF (hypoperfusion) may occur in neural regions that appear anatomically intact and may impact cognitive functioning in stroke survivors. Hypoperfusion in neurologically-involved individuals may also affect BOLD signal in FMRI studies, complicating its interpretation with this population. The current study measured CBF in three chronic stroke survivors with ischemic infarcts (greater than 1year post-stroke) to localize regions of hypoperfusion, and most critically, examine the CBF inflow curve using a methodology that has never, to our knowledge, been reported in the chronic stroke literature. CBF data acquired with a Pulsed Arterial Spin Labeling (PASL) flow-sensitive alternating inversion recovery (FAIR) technique indicated both delayed CBF inflow curve and hypoperfusion in the stroke survivors as compared to younger and elderly control participants. Among the stroke survivors, we observed regional hypoperfusion in apparently anatomically intact neural regions that are involved in cognitive functioning. These results may have profound implications for the study of behavioral deficits in chronic stroke, and particularly for studies using neuroimaging methods that rely on CBF to draw conclusions about underlying neural activity.

A single photon emission computerized tomography (SPECT) study of regional cerebral blood flow in bipolar disorder

Data on functional imaging of bipolar disorder (BD) utilizing single photon emission computerized tomography (SPECT) is limited. This study assessed regional cerebral blood flow (rCBF), using 99mTc-ECD SPECT, among patients with BD, with mania (N=10) or depression (N=10), compared with 10 patients with unipolar depression and 10 normal controls. Regions of interest were analysed using a semi-automatic brain quantification programme. Compared to controls, patients with mania had significantly reduced perfusion mainly in the left frontal area, also in the left anterior cingulate and parietal cortices; those with bipolar depression had significantly lowered rCBF principally in the anterior temporal regions bilaterally, as well as the left parietal area. Patients with unipolar depression had significantly lowered perfusion than controls in most of the regions examined, chiefly in the anterior temporal and frontal cortices bilaterally; they also had lowered perfusion in the right anterior temporal and frontal areas, as well as the right middle temporal area and the right thalamus, compared to patients with mania. Increased severity of psychotic symptoms was associated with reduced rCBF in patients. These results indicate that altered blood flow in the frontal-subcortical systems characterises patients with BD, as well as those with unipolar depression.

Apparently Asymptomatic Arachnoid Cyst: Postoperative Improvement of Subtle Neuropsychological Impediment -Case Report-

A 13-year-old right-handed boy sustained minor head trauma in a traffic accident. Computed tomography of the head showed no injuries, but revealed an arachnoid cyst in the left middle fossa. Single photon emission computed tomography revealed relatively decreased cerebral blood flow (CBF) in the left frontal and temporal lobes compared with the contralateral regions. The Wechsler Intelligence Scale for Children-Revised (WISC-R) test showed full scale intelligence quotient (IQ) was normal, but also a discrepancy between verbal IQ and performance IQ. Cyst-peritoneal shunting was performed. Postoperatively, laterality of the CBF in the frontal and temporal lobes was resolved and the verbal IQ/performance IQ discrepancy was normalized. In this case, although the WISC-R score was apparently within normal limits, latent regional ischemia induced by compression due to the arachnoid cyst may have caused neuropsychological dysfunction. CBF study and neuropsychological evaluation by the WISC-R may be useful for selecting patients with apparently asymptomatic arachnoid cysts for surgery.