PCA Territory Research Articles

Radiological imaging findings of Dyke-Davidoff-Masson syndrome.

Radiological findings of Dyke-Davidoff-Masson syndrome (DDMS) in patients with different etiologies are presented in our study. The study included 12 patients (seven females, five males) for whom radiological examinations were requested due to reasons such as epilepsy, mental retardation, and/or hemiplegia. CT was performed in 12, MRI in 6, MRA in 1, and DSA in 1 patient. Following imaging findings were evaluated: cerebral and cerebellar involvement (laterality, encephalomalacia), affected territories, ventricular enlargement, sulcal enlargement, calvarial thickening, and paranasal sinus enlargement hyperaeration. Age range of the patients was 5-62 (mean 34.1±21.7). Left hemicrania was affected in eight patients, right hemicrania in four. Ipsilateral calvarial thickening and lateral ventricular dilatation were observed in all patients. 11 patients had ipsilateral frontal sinus hyperaeration, sulcal enlargement and encephalomalacia. Wallerian degeneration of the mesencephalon and middle fossa hypoplasia was seen in ten patients, mastoid hyperaeration, third ventricular enlargement and thalamic involvement in nine, and corpus callosum, basal ganglion injury, and sphenoid sinus hyperaeration in eight. MCA, ACA, and PCA territories were involved in six patients. Only MCA territory involvement was seen in four patients. Cerebellar atrophy was contralateral in two patients. Symmetric bilateral atrophy was observed in one patient. DDMS can be encountered with different radiological findings based on cerebral damage formation process and the extent of damage. Patients may have different levels of cerebral hemiatrophy, ipsilateral carvarial thickening, and lateral ventricular dilatation.

Abstract WMP102: Infantile Spasms After Early Pediatric Arterial Ischemic Stroke.

Introduction: Symptomatic infantile spasms (SIS) constitute a debilitating epileptic encephalopathy due to an identifiable lesion in the developing brain. Perinatal and infantile arterial ischemic stroke (AIS) result in a large spectrum of developmental outcomes. Risk factors for worse outcome are not well understood, with epilepsy diagnosis being a poor prognostic factor. As a focal injury in an otherwise healthy brain, early stroke provides unique insight into the developmental effects of epileptic encephalopathy. Hypothesis: SIS are a rare complication of AIS in infancy/early childhood. Additional neurological comorbidities are seen in stroke patients with SIS. Methods: A population-based cohort of pediatric stroke (Calgary Pediatric Stroke Program) was screened. Inclusion criteria were: (1) MRI-confirmed AIS (2) age at stroke <2 years (3) EEG with hypsarrhythmia, and (4) clinical diagnosis of infantile spasms. Pediatric Stroke Outcome Measure (PSOM) was used to determine neurological outcome at follow up. Poor outcomes included total PSOM >2 and non-motor outcomes >1. Results: One hundred and sixty-three children with AIS at <2 years of age were screened. EEGs were available for 92 (56%). Five (3%) of all patients had SIS (3 symptomatic neonatal, 1 presumed perinatal, 1 childhood AIS). Four patients (80%) were male. Strokes were unilateral and involving MCA (4) and PCA (1) territories. Median age at diagnosis was 7 months (range 2-22). Four responded to either vigabatrin and/or ACTH/steroids. One was refractory to several treatments. Compared to 28/158 (18%) in the non-SIS group, 4/5 with SIS (80%) had comorbid neurological diagnoses including genetic syndromes (2), premature brain injury (1), or hypoxic ischemic encephalopathy (1). At a median follow-up of 29 months (range 6-56), all but one patient had poor neurological outcome. One patient with good outcome had no comorbidities. One patient died of causes unrelated to stroke. Conclusions: Early AIS can be complicated by infantile spasms but usually only in the context of additional neurological comrobidity. Neurological outcomes are poor but discerning the contribution of the epileptic encephlapathy is challenging as in other IS populations.

CT perfusion illustrated reversal of uncal herniation after placement of an external ventricular drain

Abstract Compression of the PCA in the context of uncal herniation is usually deducted in retrospect only with presence of a demarcated infarction in the respective territory. In this particular case with early recovery of oculomotor nerve function after CSF drainage, additional CT perfusion was able to directly document both significant compromise of the PCA as well as effective reversal of uncal herniation with restitution of perfusion within the PCA territory.

OP27 – 2989: Prevention of stroke in pediatric Moyamoya angiopathy: From diagnosis to multiple tailormade cerebral revascularisations

Objective Pediatric moyamoya is a rapidly progressive intracranial angiopathy affecting the anterior [internal carotid artery (ICA) bifurcation, middle (MCA), anterior (ACA)] and posterior (PCA) cerebral circulation. Headaches, transient Ischemic attacks (TIAs) and strokes are common initial presentations. We present the preoperative diagnostic workup, neurosurgical treatment and postoperative outcome in newly diagnosed patients referred to our Moyamoya Center, University Children's Hospital Zurich. Methods Thirty four children (female:male 21:13) diagnosed with Moyamoya angiopathy at a mean age of 7.7 years at time of surgery underwent preoperative workup and cerebral revascularisation between 2011 and 2014. Depending on clinical symptomatology, number of arterial territories involved on cerebral angiogram and extent of perfusion reserve deficits on H215-O PET with acetazolamide challenge, surgery was tailormade to each individual child. Results Bilateral angiopathy was observed in 29 patients with involvement of MCA in all, ACA in 24 and PCA in 10. All but 2 patients were clinically symptomatic at time of surgery with all showing perfusion reserve deficits after acetazolamide-H215O-PET in one or more affected arterial territories. Hundred and five revascularisations were performed with 41 in ACA (bilateral in19 patients), 54 in MCA (bilateral in 23 patients) and 10 in PCA territories (bilateral in 1 patient). Multiple combined direct (EC-IC bypass: extracranial to intracranial bypass) and indirect cerebral revascularisation procedures (EDAS: encephalo-duro-arterio-synangiosis, EGPMS: encephalo-galeaperiost-myo-synangiosis and EDS: encephalo- duro-synangiosis) were procedures of choice. There were no perioperative complications. All patients remain stroke free at 1.6 years (1 month to 3 years) follow-up. TIAs and headaches have continued in 2/33 (0.06%) and 3/33 (0.09%) patients but with reduced intensity and frequency. Long term follow-up (up to age of 18 years) continues. Conclusion Early systematic diagnostic workup is essential in pediatric moyamoya. Individualised tailor made multiple cerebral revascularisations are effective in prevention of future strokes.

SU‐D‐18C‐02: Feasibility of Using a Short ASL Scan for Calibrating Cerebral Blood Flow Obtained From DSC‐MRI

Purpose:This study aimed to evaluate the feasibility of using a short arterial spin labeling (ASL) scan for calibrating the dynamic susceptibility contrast‐ (DSC‐) MRI in a group of patients with internal carotid artery stenosis.Methods:Six patients with unilateral ICA stenosis enrolled in the study on a 3T clinical MRI scanner. The ASL‐cerebral blood flow (‐CBF) maps were calculated by averaging different number of dynamic points (N=1‐45) acquired by using a Q2TIPS sequence. For DSC perfusion analysis, arterial input function was selected to derive the relative cerebral blood flow (rCBF) map and the delay (Tmax) map. Patient‐specific CF was calculated from the mean ASL‐ and DSC‐CBF obtained from three different masks: (1)Tmax< 3s, (2)combined gray matter mask with mask 1, (3)mask 2 with large vessels removed. One CF value was created for each number of averages by using each of the three masks for calibrating the DSC‐CBF map. The CF value of the largest number of averages (NL=45) was used to determine the acceptable range(< 10%, <15%, and <20%) of CF values corresponding to the minimally acceptable number of average (NS) for each patient.Results:Comparing DSC CBF maps corrected by CF values of NL (CBFL) in ACA, MCA and PCA territories, all masks resulted in smaller CBF on the ipsilateral side than the contralateral side of the MCA territory(p<.05). The values obtained from mask 1 were significantly different than the mask 3(p<.05). Using mask 3, the medium values of Ns were 4(<10%), 2(<15%) and 2(<20%), with the worst case scenario (maximum Ns) of 25, 4, and 4, respectively.Conclusion:This study found that reliable calibration of DSC‐CBF can be achieved from a short pulsed ASL scan. We suggested use a mask based on the Tmax threshold, the inclusion of gray matter only and the exclusion of large vessels for performing the calibration.

The frequency and severity of extinction after stroke affecting different vascular territories

We examined the frequency and severity of visual versus tactile extinction based on data from a large group of sub-acute patients (n=454) with strokes affecting different vascular territories. After right hemisphere damage visual and tactile extinction were equally common. However, after left hemisphere damage tactile extinction was more common than visual. The frequency of extinction was significantly higher in patients with right compared to left hemisphere damage in both visual and tactile modalities but this held only for strokes affecting the MCA and PCA territories and not for strokes affecting other vascular territories. Furthermore, the severity of extinction did not differ as a function of either the stimulus modality (visual versus tactile), the affected hemisphere (left versus right) or the stroke territory (MCA, PCA or other vascular territories). We conclude that the frequency but not severity of extinction in both modalities relates to the side of damage (i.e. left versus right hemisphere) and the vascular territories affected by the stroke, and that left hemisphere dominance for motor control may link to the greater incidence of tactile than visual extinction after left hemisphere stroke. We discuss the implications of our findings for understanding hemispheric lateralization within visuospatial attention networks.

Outcomes of multidisciplinary treatment for posterior cerebral artery aneurysms

ObjectivePosterior cerebral artery (PCA) aneurysms are rare and often challenging to manage. Since Drake's historical report regarding PCA aneurysms, there has been limited additional information on recent advancements in either microsurgical or endovascular tools. We report a series of 25 consecutive cases and attempt to extrapolate useful information for managing PCA aneurysms. MethodsA total of 25 cases of PCA aneurysm that were treated either by microsurgical or endovascular methods were selected and retrospectively reviewed. The clinical data, radiographic findings, and outcomes associated with the treatment modality were analysed. ResultsThe case series included 13 women and 12 men with a mean age of 52 years, ranging from 11 to 75 years. Fourteen aneurysms were ruptured, 7 aneurysms caused a direct mass effect, and the remaining 4 aneurysms were found incidentally. Most aneurysms were located in the P1 through P2A segment of the PCA (19 aneurysms, 76%). Seven aneurysms (28%) were large-giant in size (>20mm), 4 of which had a thrombosed sac. Microsurgical treatment was the primary treatment in 15 aneurysms, including 9 successful direct clip ligations, 3 aneurysms that were surgically trapped without a bypass, and 2 wrapped aneurysms. One giant thrombosed aneurysm was incompletely clipped; subsequently, the large remnant was coil-embolised. Endovascular coil embolisation was performed for 6 aneurysms, stent-assisted coil embolisation was performed for 2 aneurysms, and 2 aneurysms were treated by endovascular occlusion of the parent artery. Permanent deficits acquired after treatment included limb weakness, palsy of the third cranial nerve, and hemianopsia in 5 cases (20%). There was no mortality. Overall, 22 patients (88%) showed favourable clinical outcomes according to the modified Rankin Scale Score (≤2) at the mean clinical follow-up period of 43.2 months (range: 2–130 months). ConclusionsThe present case series suggests that treating PCA aneurysms with microsurgical or endovascular options can achieve a comparable outcome when a judicious decision is made. Endovascular treatment had excellent anatomical and clinical outcomes for non-mass compressing, non-giant, saccular aneurysms. Given the propensity for the large-giant, dysplastic nature of PCA aneurysms to develop in younger patients, microsurgical competence should be maintained. Along with careful evaluation of the anatomic collaterals over the PCA territory, therapeutic parent artery sacrifice may be an appropriate option without adding bypass.

Arterial spin labelling MRI for assessment of cerebral perfusion in children with moyamoya disease: comparison with dynamic susceptibility contrast MRI

This study seeks to evaluate the diagnostic accuracy of cerebral perfusion imaging with arterial spin labelling (ASL) MR imaging in children with moyamoya disease compared to dynamic susceptibility contrast (DSC) imaging. Ten children (7 females; age, 9.2 ± 5.4years) with moyamoya disease underwent cerebral perfusion imaging with ASL and DSC on a 3-T MRI scanner in the same session. Cerebral perfusion images were acquired with ASL (pulsed continuous 3D ASL sequence, 32 axial slices, TR = 5.5s, TE = 25ms, FOV = 24cm, matrix = 128 × 128) and DSC (gradient echo EPI sequence, 35 volumes of 28 axial slices, TR = 2,000ms, TE = 36ms, FOV = 24cm, matrix = 96 × 96, 0.2ml/kg Gd-DOTA). Cerebral blood flow maps were generated. ASL and DSC images were qualitatively assessed regarding perfusion of left and right ACA, MCA, and PCA territories by two independent readers using a 3-point-Likert scale and quantitative relative cerebral blood flow (rCBF) was calculated. Correlation between ASL and DSC for qualitative and quantitative assessment and the accuracy of ASL for the detection of reduced perfusion per territory with DSC serving as the standard of reference were calculated. With a good interreader agreement (κ = 0.62) qualitative perfusion assessment with ASL and DSC showed a strong and significant correlation (ρ = 0.77; p < 0.001), as did quantitative rCBF (r = 0.79; p < 0.001). ASL showed a sensitivity, specificity and accuracy of 94%, 93%, and 93% for the detection of reduced perfusion per territory. In children with moyamoya disease, unenhanced ASL enables the detection of reduced perfusion per vascular territory with a good accuracy compared to contrast-enhanced DSC.

Acute Korsakoff's Psychosis and Disinhibition Syndrome Triggered by a Cortical Posterior Cerebral Artery Infarction (P07.182)

Objective: We report an unusual case of a dominant hemisphere, medial occipital and medial temporal cortical infarction precipitating Korsakoff9s psychosis and a disinhibition syndrome, reminiscent of a frontal lobe phenotype. A 66 year-old, right handed man, while driving to watch the Monaco Grand Prix, developed acute headache and amnesia accompanied by emotional lability, disinhibited behavior, inappropriate laughter and a right homonymous hemianopia. He had deficits in both episodic and working memory, a mild degree of executive dysfunction and a tendency to confabulate. There were no other focal neurological signs. He had been well previously, except for moderately high alcohol consumption. The cognitive deficits persisted 6 months after presentation, despite thiamine replacement. Acute imaging demonstrated restricted diffusion in the medial occipital and temporal lobes involving the fusiform and parahippocampal gyri with sparing of thalamus and other deeper structures. The rest of the parenchymal structures were normal and there was no evidence of small vessel ischaemia. An occlusion of P2 segment of the left posterior cerebral artery and its cortical branches was seen on vascular imaging. Cognitive deficits associated with posterior cerebral artery infarctions include a constellation of behavioural symptoms including transcortical aphasia, alexia without agraphia, Gerstmann syndrome, episodic memory deficit, visual agnosia, prosopagnosia and rarely acute delirium with/without aggressive behavior. Disinhibition syndromes of frontal phenotype have rarely been reported and may be associated with cortical deafferentation following a non-dominant thalamic lesion. This case demonstrates that behavioural deficits after cortical PCA territory infarction are not restricted to memory, language and vision and may occur without thalamic involvement. We hypothesise that the Korsakoff9s syndrome may have been the result of a functional disruption of mamillothalamic connections, as previously described, whereas the frontal behavioural features may be caused by a disruption of occipito temporal and occipito frontal connectivity. Disclosure: Dr. Agarwal has nothing to disclose. Dr. Manford has received personal compensation for activities with UCB Pharma and Eisai.

005 Intravenous thrombolysis in acute ischaemic stroke: experience in a developing country

Aims and ObjectivesThis is an observational study of the patients thrombolysed in a multispeciality hospital in private sector in India.Materials and MethodThe study was carried out in a 400-bedded hospital...

Abstract 3095: CT Perfusion Deficits Are Present in Acute Transient Ischemic Attack Patients Utilizing 320 Detector Row Whole Brain CT Perfusion Studies and are Associated with ABCD2 score

INTRODUCTION: Transient ischemic attacks (TIA) are generally milder forms of cerebral ischemia, without end organ damage. However, infarction or permanent ischemia is seen in TIA. The use of perfusion techniques such as cerebral blood volume (CBV), time to peak (TTP), mean transit time (MTT), and cerebral blood flow (CBF) provide real time data about ischemia. Whole brain CT perfusion studies are limited to only a few dozen stroke centers that have high detector row CT scanners. OBJECTIVE: To demonstrate that TIA's have significant numbers of perfusion deficits using whole brain 320 detector row CT perfusion, and to show an association between the ABCD2 score and the presence of perfusion deficit using whole brain perfusion. METHODS: We retrospectively reviewed all TIA patients for CT perfusion deficits at our "Gold+, JACHO" stroke center from 2008 to 2010. Exclusion criteria included patients who did not receive a CT scan during the study period and all ischemic or hemorrhagic stroke patients as confirmed by MRI or CT. Patients that had an ABCD2 score at time of imaging/admission were included in the study. Perfusion imaging was reviewed at admission by a neurologist and a radiologist; and reports stated if a perfusion deficit was noted, type (CBV, TTP, MTT, CBF) and vascular territory. RESULTS: Of 368 TIA patients, 66 patients had perfusion deficits. The largest group of patients had MCA territory involved at 52 of 66 (78.79%). The second largest of the groups was 11 (16.67%) with PCA territory or posterior fossa involved. Lastly 3 patients had ACA territory involvement (4.55%).The most common perfusion abnormality was increased TTP with 48 patients(72.73%). Increased MTT was noted in 17 patients (25.76%) and change in CBF in 14 patients (21.21%); and 6 patients with decreased CBV (9.09%). Using logistic regression, the components of ABCD2 score (age, blood pressure, character of symptoms, history of diabetes, and duration of symptoms) were reviewed in relation to the presence of perfusion deficit. Increased age greater than 65, hypertension (both systolic and diastolic) at the time of the TIA, patients that had weakness rather than only speech abnormalities, and duration of symptoms longer than an hour were all more likely to have a perfusion deficit. However, a history of diabetes or hypertension was not associated with a higher likelihood of perfusion deficit. DISCUSSION: The ABCD2 score can determine whether TIA patients are admitted for other diagnostic tests. Attention to CT perfusion in association with ABCD2 scores may better address potential risk factors of secondary stroke. CONCLUSION: There are perfusion deficits in TIA patients using 320 detector row whole brain perfusion protocol. Also, worsening criteria in each of the ABCD2 score modalities, except diabetes, is associated with a higher likelihood of a perfusion deficit.

Abstract 54: Mapping of Cerebral Vascular Territories Using Whole Brain Perfusion CT Imaging: A New Method

Introduction: The nature and endurance of the collateral blood supply in acute stroke is speculated to play a key role in tissue survival, yet research in this area is limited by the lack of appropriate imaging modalities to characterize and quantify collateral flow. We present the first results of a novel post-processing technique that can label and quantify the extent of the major vascular territories, including the predominant source of collateral supply into the hypo-perfused regions, using a 320 slice whole brain perfusion CT acquisition. Hypothesis: We hypothesized that the perfusion territories determined by the algorithm would be anatomically consistent with what would be expected from the site of occlusion as determined on CTA. Methods: We retrospectively selected data from a cohort of 19 acute stroke patients imaged within 6 h of stroke onset on a Toshiba Aquilion One CT system. We applied an algorithm that uses subtle changes in bolus shape across voxels to infer the pathway of flow from the proximal vessels towards the periphery. Labels were assigned to each of the 6 feeding vessels and the vascular territory maps were generated. Each voxel is color coded by its dominant source of flow. Results: We were able to generate images in 15 of 19 cases [4 excluded due to head motion and poor signal enhancement during the bolus passage]. In general, the estimated distributions of vascular territories in the non affected hemisphere were in agreement with text book distribution patterns. In the affected hemisphere, the vascular territory of the occluded vessel was either diminished or absent and the tissue instead supplied by adjacent territories. In 2/15 cases the estimated collateral territory appeared questionable. The figure shows two typical cases: In patient 1 with a distal M1 occlusion, the MCA territory is partially taken over by the ACA and PCA territories. In patient 2, the PCA collateralisation recedes following partial reperfusion of the M2 branch occlusion. Conclusion: This perfusion CT post-processing technique opens a window to visualization and measurement of vascular supply territories using a routine perfusion CT scan, an application previously limited to arterial spin labelling MRI. This technique is complementary to standard perfusion maps, and we speculate that integration of collateral supply information may enhance the utility of perfusion imaging and ultimately lead to more accurate selection of treatment responders. This new post-processing method has the potential to characterise and quantify collateral circulation with no need for additional hardware or higher radiation doses.

Abstract 2356: Predicting Factors Of Developing The Malignant Middle Cerebral Artery (MCA) Infarction For An Acute Mca Infarction With Main Mca Occlusion

Background : Malignant middle cerebral artery (MCA) infarction is leading cause of death for acute MCA infarction patients. Early detection of patients who can develop the malignant MCA infarction (MMI) is important for timely decision for life-saving treatment such as an decompressive surgery. So we studied to figure out a reliable predicting parameters for developing MMI using acute stroke magnetic resonance imaging (MRI) such as diffusion and perfusion images. Methods : We included 209 MCA infarction patients with main MCA occlusion within 6 hours of symptom onset between January 2007 and December 2010 in Dong-A University Stroke center. All patients were performed brain MRI including diffusion and perfusion images. Vessel occlusion was diagnosed by MR angiography. We used regional cerebral blood volume (rCBV) ratio as a representing parameters of perfusion image. The rCBV ratio was calculated by comparing the blood volume of the ischemic lesion with that of the corresponding unaffected contralateral region.Definition of the malignanat MCA infarction was as following : 1) deterioration of neurological and consciousness with clinical signs of uncal herniation and mass effect, 2) large space-occupying MCA infarction or at least two-third of the MCA territory with compression of ventricles of midline shifting. We observed any changes of neurological deterioration within 7 days of symptom onset. Severity of neurological symptom and clinical outcome were assessed by using National Institute Stroke Severity Scale (NIHSS) and the modified Rankin Scale (mRS). Results : Among 209 pts, 84 (40.2%) developed MMI, and 125 (59.8%) did not (non-MMI). In a univariate analysis, MMI group was more older (69.08 vs 63.54), more additional lesion in ACA or PCA territory (13.1% vs 1.6%), higher NIHSS score. In MMI group, MCA with ipsilateral ICA occlusion was more frequent (76.2% vs 40.0%), and larger diffusion volume (99.13 vs 21.57), lower rCBV ratio (0.53 vs 0.87). Also, the presence of diffusion-perfusion mismatch (DPM) was more common in non-MMI group (80.8% vs 46.4%). In MMI group, large portion of patients were included in mRS 5-6 group (61.4%) compared with non-MMI group (15.8%). In a multivariate analysis, these parameters were identified as a predicting factors of MMI : larger diffusion volume (OR :1.02, 1.01-1.04, p&lt;0.001), lower rCBV ratio (OR :0.97, 0.95-0.99, p&lt;0.001), higher NIHSS on admission (OR: 1.31, 1.16-1.47, p&lt;0.001). The cutoff value of diffusion volume, NIHSS on admission and rCBV ratio were 69ml, 15 point and 0.66 respectively. Conclusion : Brain MRI including diffusion and perfusion image, especially diffusion volume and rCBV ratio can predict malignant course in MCA infarction with main MCA occlusion patients within 6 hours of symptom onset.

Short- and Long-Term Hemodynamic and Clinical Effects of Carotid Artery Stenting

Stenosis of the carotid artery may cause reduced hemodynamic and neural function that may be ameliorated with CAS. The goal of this study was to evaluate short- and long-term hemodynamic and clinical effects after CAS. Hemodynamic parameters were acquired by PCT within 1 week before CAS and at 1 week and 1 year (10-13 months) after CAS. In ACA territory, MCA territory, PCA territory, basal ganglia, anterior and posterior CWS and IWS, the rCBF, rCBV, and rMTT were determined in 20 patients with unilateral carotid artery stenosis who underwent CAS. MR and noncontrast CT were performed within 1 week before CAS. Noncontrast CT and carotid arteriography were performed immediately after CAS. Carotid arteriography was performed 1 year after CAS. MRS was performed in 3 measurements. The variance analysis was performed to determine whether there were significant differences among the 3 measurements. No significant differences were found among rCBV in any territory (P > .05). In the non-PCA territories, rMTT decreased and rCBF increased at 1 week after CAS (P < .01), but there was no significant difference between 1-week and 1-year effects (P > .05). For MR spectroscopy, no significant differences were found between 1 week after CAS and pretreatment (P > .05); the 1-year scores improved significantly (P < .01). The long-term hemodynamic and clinical results after treatment validated that CAS is a durable procedure. The 1-week hemodynamic effects can predict long-term effects.

Changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery

To evaluate changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery in the patients who underwent ischemic stroke caused by carotid artery stenosis. Twenty patients with unilateral symptomatic carotid artery stenosis received brain computer tomography perfusion (CTP) scan a week before and a week after carotid artery stenting. Three absolute values including mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were acquired and analyzed by use of the post-processing software. Six vascular territories such as ACA territory, MCA territory, PCA territory, basal ganglia, watershed between ACA and MCA territory (frontal watershed), watershed between MCA and PCA territory (posterior watershed) were chosen for comparison. Relative parameter values were defined as rCBF (relative CBF), rCBV (relative CBV), rMTT (relative MTT) through comparing absolute values in symptomatic hemispheres to absolute values in asymptomatic hemispheres. The relative perfusion parameter values before treatment were compared with post-treatment values. These analyses were performed by using the paired t test. The mean rMTT decreased significantly in ACA territory, MCA territory and two watershed after treatment, while the mean rCBF increased significantly in those areas after treatment. But the mean rCBV had no significant changes in all six vascular territories. In PCA territory, all the parameters had no significant changes. Carotid artery stenting yields satisfactory cerebral perfusion in ACA territory, MCA territory, basal ganglia and two watersheds.

The Prognostic Factors That Influence Long-Term Survival in Acute Large Cerebral Infarction

We retrospectively evaluated the prognostic factors that can influence long-term survival in patients who suffered acute large cerebral infarction. Between June 2003 and October 2008, a total of 178 patients were diagnosed with a large cerebral infarction, and, among them, 122 patients were alive one month after the onset of stroke. We investigated the multiple factors that might have influenced the life expectancies of these 122 patients. The mean age of the patients was 70±13.4 years and the mean survival was 41.7±2.8 months. The mean survival of the poor functional outcome group (mRS≥4) was 33.9±3.3 months, whereas that of the good functional outcome group (mRS≤3) was 58.6±2.6 months (p value =0.000). The mean survival of the older patients (≥70 years) was 29.7±3.4 months, whereas that of the younger patients (<70 years) was much better as 58.9±3.2 months (p value=0.000). Involvement of ACA or PCA territory in MCA infarction is also a poor prognostic factor (p value=0.021). But, other factors that are also known as significant predictors of poor survival (male gender, hypertension, heart failure, atrial fibrillation, diabetes mellitus, a previous history of stroke, smoking, and dyslipidemia) did not significantly influence the mean survival time in the current study. Age (older versus younger than 70 years old) and functional outcome at one month could be critical prognostic factors for survival after acute large cerebral infarction. Involvement of ACA or PCA territory is also an important poor prognostic factor in patients with MCA territorial infarction.

Abstract 5108: Variation in Pial Collaterals in 15 Mouse Strains is a Major Determinant of Infarct Volume After Middle Cerebral Artery Occlusion (MCAO)

The importance of vascular, non-vascular and genetic factors in the wide variability in severity of infarct volume (IV) is unclear. We have reported previously that density and diameter of native collaterals in tissues vary widely with genetic background. The purpose of this study was to determine the contribution of genetic variation in collaterals to variation in IV in a cohort of genetic reference strains. IV was determined 1 day after MCAO. In a second set of mice, the vasculature was dilated, fixed and cast 6 days after MCAO. The number and diameter of pial collaterals were determined for the unligated left and ligated right hemispheres, as were territories of the MCA, ACA and PCA trees. Variations among strains in IV, native collateral number and diameter, and MCA, ACA and PCA territories were, respectively: 30-fold, 56-fold, and 3-fold, and 42%, 56% and 61%. IV and collateral dimensions did not correlate with brain size or PCA territory, but IV correlated highly with collateral number and diameter ((p&lt;0.0001), and less so with MCA (p&lt;0.05) and ACA territory (p&lt;0.01). Arrangement of these parameters (excepting IV) into an expression of collateral conductance strongly predicted IV (p&lt;0.0001). Prediction was improved by factoring in collateral length and hematocrit. There was no correlation between MCA territory and collateral number or diameter, suggesting genetic determinants of tree territory do not specify collateral dimensions. However, collateral dimensions were highly inter-correlated, suggesting they could arise from common genetic variants. Increase in collateral diameter on the ligated side (remodeling) varied by more than 2-fold and correlated with collateral diameter (p&lt;0.0001) and number (p&lt;0.01). Genome-wide haplotype and C57BL/6 × BALB/cBy F2 mapping are underway to identify potential loci harboring variants important in collateral formation. These data suggest that conductance of the pial collateral circulation is the primary determinant of stroke severity, and that polymorphisms in genes specifying formation of the native collateral circulation and its remodeling in ischemia are important determinants of stroke risk and stroke variance. These findings may generalize to heart, limb and other tissues.

Fetal Origin of the Posterior Cerebral Artery Produces Left-Right Asymmetry on Perfusion Imaging

Fetal origin of the PCA is a common anatomic variation of the circle of Willis. On perfusion imaging, patients with unilateral fetal-type PCA may demonstrate left-right asymmetry that could mimic cerebrovascular disease. The aim of this study was to characterize the relationship between a fetal-type PCA and asymmetry of hemodynamic parameters derived from MR perfusion imaging. We retrospectively reviewed MR perfusion studies of 36 patients to determine the relationship between hemodynamic and vascular asymmetries in the PCA territory. Perfusion asymmetry indices for the PCA territory were computed from maps of rCBF, rCBV, MTT, T(max), and FMT. Vascular asymmetry indices were derived from calibers of the PCA-P1 segments relative to the posterior communicating arteries. Asymmetrically smaller values of FMT and T(max) were observed with unilateral fetal-type PCA, and these were strongly correlated with the degree of vascular asymmetry (Spearman's rho = 0.76 and 0.74, respectively, P < 1 x 10(-6)). Asymmetries of rCBF, MTT, and rCBV were neither significant nor related to vascular asymmetry. Faster perfusion transit times are seen for parameters sensitive to macrovascular transit effects (eg, FMT and T(max)) ipsilateral to fetal origin of the PCA in proportion to the degree of arterial asymmetry. Knowledge of this normal variation is critical in the interpretation of perfusion studies because asymmetry could mimic cerebrovascular pathology.

Cerebral Blood Flow Measurement in Children with Sickle Cell Disease Using CASL at 3.0 Tesla MRI

One of the most devastating complications of SCD is cerebral infarction. Cerebral infarcts are present on MRI scans in one third of SCD patients at the age of 18 years, although most of them are not accompanied by overt, focal neurological deficits. These so-called silent infarcts appear to be associated with diminished neurocognitive functioning and an increased risk of new infarcts. The risk of infarction is commonly attributed to the hyperemia that is associated with anemia and reduces the cerebral vascular reserve. In patients with anemia, adequate oxygenation of the brain tissue is presumably preserved by vasodilatation of the cerebral vasculature. In this hyperemic state there is limited reserve for further vasodilatation to assure adequate oxygen supply to the brain if the arterial pressure falls or metabolic demands increase. The lack of reserve capacity and ensuing ischemia is thought to predispose to cerebral infarction. The regional cerebral blood flow (rCBF) can be measured non-invasively by continuous arterial spin labeling (CASL) MRI. Proximal to entry in the brain, protons in the arterial blood are labeled using a radiofrequency pulse and quantified in terms of tissue perfusion on distal images in the brain. We performed a study to evaluate whether CASL MRI could detect differences in rCBF when these regions appear unaffected on conventional 3T MRI. The purpose of this study was to examine rCBF in children with SCD and compare it to rCBF in healthy children. Neurologically normal patients with sickle cell disease (HbSS or HbS-β0-thalassemia) and normal flow on Transcranial Doppler Ultrasonography (TCD) and healthy children (HbAA, matched for ethnicity and age) underwent 3T MRI examination in a stable clinical situation between August 2006 and June 2007. Conventional MRI and MRA images were assessed by a standardized evaluation protocol by two independent observers (MW and CM), blinded to the clinical data. Cerebral infarcts, leukoareosis and vasculopathy were scored. From CASL MRI the rCBF was calculated for 6 vascular territories (left and right anterior, middle and posterior cerebral artery, respectively ACA, MCA and PCA). Left-right asymmetry in rCBF for the vascular territories within each patient was evaluated by calculating differences in flow between both hemispheres. Asymmetry was defined as > 11.7 ml/100g/min between the two hemispheres. Mean differences between patients and controls and 95% confidence intervals were calculated. The Chi-square test was performed to test the hypothesis that left-right asymmetry was equally distributed among the patients and controls. We enrolled 24 SCD patients (mean age 13.4 yr, SD 3.0) and 12 controls (mean age 13.4 yr, SD 3.5). The rCBF was of similar magnitude in SCD patients and controls in the frontal, middle and posterior territories (Table 1). A left-right asymmetry of rCBF in one or more vascular territories was present in the majority of SCD patients (58%), whereas this was absent in all controls. The difference in proportions of patients and controls with left-right asymmetry was statistically significant for the MCA and PCA territory (Chi-square test respectively p=0.005 and p=0.037). In contrast to previous studies we found no difference in CBF between patients and controls. We did observe an asymmetry in rCBF in the majority of patients with SCD that was not present in healthy controls.Table 1. rCBF (ml/100g/min) values of patients and healthy controls.Patients n=24Healthy controls n=12Mean difference95% CITerritoriesMeanSDMeanSDACA73.217.471.514.4−1.7(−13.6–10.1)MCA77.119.976.116.4−1.0(−14.5–12.5)PCA89.616.484.516.6−5.1(−17.0–6.7)Right hemisphere77.619.276.315.3−1.3(−14.3–11.5)Left hemisphere77.517.776.616.1−0.9(−13.3–11.4)Total77.617.476.415.6−1.2(−13.4–11.0)

Regional Cerebral Autoregulation During Orthostatic Stress: Age-Related Differences

We used transcranial Doppler ultrasonography to examine the cerebral blood flow response to orthostatic stress in the middle and posterior cerebral circulations and to determine the effects of healthy aging on regional cerebral blood flow regulation. Continuous simultaneous middle (MCA) and posterior (PCA) cerebral artery blood flow velocities (BFV) and mean arterial pressure (MAP) were measured in response to standing from a sitting position in 13 younger (30 +/- 7 years) and 13 older (73 +/- 4 years) healthy participants. The older participants had a significantly larger decline in MAP (-31% +/- 3 in the older and -21% +/- 2 in the younger) and a smaller increase in heart rate (HR) (15 bpm +/- 1 in the older, 24 bpm +/- 2 in the younger) during the posture change. Despite a larger decline in MAP, the older participants had a decline very similar to that of the younger participants in BFVs in both vascular territories. This was associated with a significantly larger vasodilatory response in the MCA and PCA vascular territories of the older participants. There were no regional differences of the cerebrovascular resistance and BFV responses to orthostasis in the younger participants. However, in the older participants, there was a significantly larger BFV decline and a smaller vasodilatory response in the PCA as compared to the MCA territory. Healthy aging is associated with preserved cerebrovascular adaptation to orthostatic hypotension. However, in older persons, the PCA territory blood flow may be more vulnerable to reduced perfusion during orthostatic stress.