Cerebrovascular Reserve Research Articles

Efficacy of butylphthalide in the treatment of patients with stroke attributed to intracranial arterial stenosis.

To explore the clinical efficacy of butylphthalide in treating patients with stroke attributed to intracranial artery stenosis (ICAS). In this retrospective study, records of 163 patients with stroke attributed to ICAS admitted to Jiaxing Second Hospital from January 2021 to January 2023 were retrospectively analyzed. Patients were divided into two groups based on the treatment received: control group (patients received routine treatment, n=55) and observation group (patients treated with butylphthalide on a routine basis, n=58). Changes in levels of cerebrovascular reactivity (CVR), breath-holding index (BHI), pulsatility index (PI), and middle cerebral artery mean flow velocity (Vm) between the two groups before and after treatment were compared. In addition, cognitive function, neurological function, and living ability were compared between the two groups before and after treatment, as well as the overall clinical efficacy of the treatment. The baseline data was comparable between the two groups (P>0.05). After the treatment, CVR, BHI, and Vm indicators in the observation group were significantly higher than those in the control group, while the levels of PI indexes were significantly lower than those in the control group (P<0.05). Montreal Cognitive Assessment (MoCA) and Barthel scale scores of the observation group were significantly higher compared to the control group, while the scores of National Institutes of Health Stroke Scale (NIHSS) were significantly lower (P<0.05). Butylphthalide in addition to routine treatment can effectively improve cerebrovascular reserve function, promote neurological and cognitive dysfunction recovery, and enhance daily living ability of patients with stroke caused by ICAS.

Prediction of cerebral infarction after bypass surgery in adult moyamoya disease: using pulsatility index on TCD

BackgroundAt present, the most effective treatment for symptomatic moyamoya disease (MMD) is surgery. However, the high incidence of postoperative complications is a serious problem plaguing the surgical treatment of MMD, especially the acute cerebral infarction. Decreased cerebrovascular reserve is an independent risk factor for ischemic infarction, and the pulsatility index (PI) of transcranial Doppler (TCD) is a common intuitive index for evaluating intracranial vascular compliance. However, the relationship between PI and the occurrence of ischemic stroke after operation is unclear.ObjectiveTo explore whether the PI in the middle cerebral artery (MCA) could serve as a potential predictor for the occurrence of ischemic infarction after bypass surgery in MMD.MethodsWe performed a retrospective analysis of data from 71 patients who underwent combined revascularization surgery, including superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis and encephalo-duro-myo-synangiosis (EDMS). The patients were divided into two groups according to the median of ipsilateral MCA-PI before operation, low PI group (MCA-PI < 0.614) and high PI group (MCA-PI ≥ 0.614). Univariate and multivariate regression analysis were used to explore risk factors affecting the occurrence of postoperative cerebral infarction.ResultsAmong the 71 patients with moyamoya disease, 11 patients had cerebral infarction within one week after revascularization. Among them, 10 patients’ ipsilateral MCA-PI were less than 0.614, and another one’s MCA- PI is higher than 0.614. Univariate analysis showed that the lower ipsilateral MCA-PI (0.448 ± 0.109 vs. 0.637 ± 0.124; P = 0.001) and higher Suzuki stage (P = 0.025) were linked to postoperative cerebral infarction. Multivariate analysis revealed that lower ipsilateral MCA-PI was an independent risk factor for predicting postoperative cerebral infarction (adjusted OR = 14.063; 95% CI = 6.265 ~ 37.308; P = 0.009).ConclusionsA lower PI in the ipsilateral MCA may predict the cerebral infarction after combined revascularization surgery with high specificity. And combined revascularization appears to be safer for the moyamoya patients in early stages.

Assessment of MR blood-oxygen-level-dependent (BOLD) cerebrovascular reactivity under general anesthesia in children with moyamoya.

Moyamoya is a progressive, non-atherosclerotic cerebral arteriopathy that may present in childhood and currently has no cure. Early diagnosis is critical to prevent a lifelong risk of neurological morbidity. Blood-oxygen-level-dependent (BOLD) MRI cerebrovascular reactivity (CVR) imaging provides a non-invasive, in vivo measure of autoregulatory capacity and cerebrovascular reserve. However, non-compliant or younger children require general anesthesia to achieve BOLD-CVR imaging. To determine the same-day repeatability of BOLD-CVR imaging under general anesthesia in children with moyamoya. Twenty-eight examination pairs were included (mean patient age = 7.3 ± 4.0years). Positive and negatively reacting voxels were averaged over signals and counted over brain tissue and vascular territory. The intraclass correlation coefficient (ICC), Wilcoxon signed-rank test, and Bland-Altman plots were used to assess the variability between the scans. There was excellent-to-good (≥ 0.59) within-day repeatability in 18 out of 28 paired studies (64.3%). Wilcoxon signed-rank tests demonstrated no significant difference in the grey and white matter CVR estimates, between repeat scans (all p-values > 0.05). Bland-Altman plots of differences in mean magnitude of positive and negative and fractional positive and negative CVR estimates illustrated a reasonable degree of agreement between repeat scans and no systematic bias. BOLD-CVR imaging provides repeatable assessment of cerebrovascular reserve in children with moyamoya imaged under general anesthesia.

Amelioration of gait and balance disorders by rosuvastatin is associated with changes in cerebrovascular reactivity in older patients with hypertensive treatment.

To investigate the effect of rosuvastatin on gait and balance disorder progression and elucidate the role of cerebrovascular reactivity (CVR) on this effect. From April 2008 to November 2010, 943 hypertensive patients aged ≥60 years were enrolled from the Shandong area of China. Patients were randomized into rosuvastatin and placebo groups. Gait, balance, CVR, fall and stroke were assessed. During an average 72 months of follow-up, the decreasing trends for step length, step speed, and Berg balance scale scores and the increasing trends for step width and chair rising test were slower in the rosuvastatin group when compared to the placebo group. The hazard ratio of incident balance impairment and falls was 0.542 [95% confidence interval (CI) 0.442-0.663] and 0.532 (95% CI 0.408-0.694), respectively, in the rosuvastatin group compared with placebo group. For CVR progression, the cerebrovascular reserve capacity and breath-holding index were increased and the pulsatility index decreased in the rosuvastatin group, while the cerebrovascular reserve capacity and breath-holding index were decreased, and pulsatility index increased in the placebo group. The changes in gait stability and balance function were independently associated with the changes in the CVR. The odds risks of balance impairment and falls were 2.178 (95% CI: 1.491-3.181) and 3.227 (95% CI: 1.634-6.373), respectively, in the patients with CVR impairment and patients without CVR impairment. Rosuvastatin ameliorated gait and balance disorder progression in older patients with hypertension. This effect might result from the improvement in the CVR. This double-blind clinical trial recruited 943 hypertensive patients aged ≥60 years who were randomly administered rosuvastatin and placebo interventions. The data indicates that rosuvastatin significantly ameliorated the progressions of gait and balance disorders in older hypertensive patients. The cerebrovascular reactivity might play an important mediating role in this amelioration.

Non-Invasive Tools in Perioperative Stroke Risk Assessment for Asymptomatic Carotid Artery Stenosis with a Focus on the Circle of Willis.

This review aims to explore advancements in perioperative ischemic stroke risk estimation for asymptomatic patients with significant carotid artery stenosis, focusing on Circle of Willis (CoW) morphology based on the CTA or MR diagnostic imaging in the current preoperative diagnostic algorithm. Functional transcranial Doppler (fTCD), near-infrared spectroscopy (NIRS), and optical coherence tomography angiography (OCTA) are discussed in the context of evaluating cerebrovascular reserve capacity and collateral vascular systems, particularly the CoW. These non-invasive diagnostic tools provide additional valuable insights into the cerebral perfusion status. They support biomedical modeling as the gold standard for the prediction of the potential impact of carotid artery stenosis on the hemodynamic changes of cerebral perfusion. Intraoperative risk assessment strategies, including selective shunting, are explored with a focus on CoW variations and their implications for perioperative ischemic stroke and cognitive function decline. By synthesizing these insights, this review underscores the potential of non-invasive diagnostic methods to support clinical decision making and improve asymptomatic patient outcomes by reducing the risk of perioperative ischemic neurological events and preventing further cognitive decline.

A mathematical model for temporal cerebral blood flow response to acetazolamide evaluated in patients with Moyamoya disease

Background: Paired cerebral blood flow (CBF) measurement is usually acquired before and after vasoactive stimulus to estimate cerebrovascular reserve (CVR). However, CVR may be confounded because of variations in time-to-maximum CBF response (tmax) following acetazolamide injection. With a mathematical model, CVR can be calculated insensitive to variations in tmax, and a model offers the possibility to calculate additional model-derived parameters. A model that describes the temporal CBF response following a vasodilating acetazolamide injection is proposed and evaluated. Methods: A bi-exponential model was adopted and fitted to four CBF measurements acquired using arterial spin labelling before and initialised at 5, 15 and 25 min after acetazolamide injection in a total of fifteen patients with Moyamoya disease. Curve fitting was performed using a non-linear least squares method with a priori constraints based on simulations. Results: Goodness of fit (mean absolute error) varied between 0.30 and 0.62 ml·100 g-1·min-1. Model-derived CVR was significantly higher compared to static CVR measures. Maximum CBF increase occurred earlier in healthy- compared to diseased vascular regions. Conclusions: The proposed mathematical model offers the possibility to calculate CVR insensitive to variations in time to maximum CBF response which gives a more detailed characterisation of CVR compared to static CVR measures. Although the mathematical model adapts generally well to this dataset of patients with MMD it should be considered as experimental; hence, further studies in healthy populations and other patient cohorts are warranted.

Cortical Spreading Depolarization in Moyamoya Vasculopathy: A Case Series.

Spreading depolarization describes a near-complete electrical discharge with altered local cerebral blood flow. It is described in association with acute and chronic diseases like hemorrhagic stroke or migraine. Moyamoya vasculopathy is a chronic, progressive cerebrovascular disorder leading to cerebral hypoperfusion, hemodynamically insufficient basal collateralization, and increased cortical microvascularization. In a prospective case series, we monitored for spontaneous spreading depolarization activity by using intraoperative laser speckle imaging for real-time visualization and measurement of cortical perfusion and cerebrovascular reserve capacity during cerebral revascularization in 4 consecutive patients with moyamoya. Spontaneous spreading depolarization occurrence was documented in a patient with moyamoya before bypass grafting. Interestingly, this patient also exhibited a marked preoperative increase in angiographic collateral vessel formation. The spontaneous occurrence of SDs in moyamoya vasculopathy could potentially provide an explanation for localized cortical infarction and increased cortical microvascular density in these patients.

Abstract 115: Presenting Symptoms and Neuroimaging Correlates in North American Moyamoya Vasculopathy

Introduction: Moyamoya disease (MMD) is a steno-occlusion of the supraclinoid internal carotid arteries and proximal branches with the development of collateral vessels 1 . Once thought to affect primarily females of East Asian descent, more than 11,000 hospitalizations in patients with MMD of non-Asian ancestry are reported annually in the USA, with the majority presenting with ischemic stroke. Here, we present frequent non-stroke symptomatology in North American MMD along with hemodynamic imaging profiles at presentation. Methods: Participants provided informed consent and underwent anatomical MRI with hypercapnic blood oxygenation level-dependent 2 ; time regression was applied to quantify cerebrovascular reactivity (CVR) and reactivity delay time (CVR DELAY ) 3 in right and left MCA territories. A logistic regression analysis based on the Huber-White sandwich estimator compared the CVR metrics between cohorts. Significance criterion: Bonferroni corrected two-sided p&lt;0.05. Results: 74 patients (age=11-77 years; Asian=6%, White=65%, Black=29%) diagnosed with MMD with symptom durations spanning hours to years prior to presentation were enrolled. Non-stroke symptoms and frequency prior to stroke are listed in Table 1. In more than 1/3 rd of patients, unprovoked headaches preceded stroke-like symptoms. In patients exhibiting ischemic symptoms within six months of neuroimaging, cerebrovascular reserve capacity was reduced (p=0.007), and cerebrovascular reactivity delay time increased (p&lt;0.001), in the flow territory from which symptoms were derived compared to the contralateral flow territory. Discussion: North American MMD is being observed with increasing frequency and increasing the awareness of non-stroke MMD presentations may lead to early diagnosis that can lead to proactive revascularization to minimize the risk of first stroke in these patients.

Evaluating the Status of the Injured Brain: Cerebrovascular Reserve (CVR) Is Not Equivalent to Induced Cerebrovascular Reactivity (iCVRx) and Induced Pressure Reactivity (iPRx) in Defining the Critical Cerebral Perfusion Pressure (CPP).

Methods evaluating the status of the injured brain have evolved over the past 63years since Lundberg first reported clinical measurement of intracranial pressure (ICP) to evaluate the status of the injured brain (Lundberg, Acta Psychiatr Scand Suppl. 36:1-193, 1960). Subsequent evaluation involved measurement of the autoregulatory capacity of the brain by measuring cerebral blood flow (CBF) with decreasing mean arterial pressure (MAP) to define the critical CPP where the vasodilatory capacity of the cerebral circulation is exceeded and CBF begins to fall (CPP of 50mmHg). A seminal advance was made by Marmarou (Marmarou et al., J Neurosurg. 48:332-344, 1978) who measured brain compliance by injecting a bolus of saline into the intracranial catheter while measuring the rise in intracranial pressure (ICP) otherwise known as induced pressure reactivity (iPRx). Seeking to utilise continuous measurement of iPRx in traumatic brain injury (TBI) patients with continuous monitoring of ICP, the ICP response to arterial pulsations was developed to evaluate the optimal CPP patients with raised ICP by the arterial pulsations-based iPRx. A similar approach was made with Doppler measurement of CBF with arterial pulsations for iCVRx to guide optimal CPP (CPPopt). Both iPRx and iCVRx are associated with microvascular shunts (MVS) and can accurately measure the critical CPP, whereas the CBF autoregulation curve by decreasing MAP does not. Sophisticated continuous multimodal monitoring established with ICM+ algorithms successfully identifies CPPopt for ICP control and identifies CBF dysregulation as related to outcome, but does not provide insights into the mechanisms involved in the loss of CBF autoregulation as related to increased ICP and potentially effective treatments (Froese et al., Neurocrit Care. 34:325-335, 2021).

High inspired CO2 target accuracy in mechanical ventilation and spontaneous breathing using the Additional CO2 method.

Cerebrovascular reactivity imaging (CVR) is a diagnostic method for assessment of alterations in cerebral blood flow in response to a controlled vascular stimulus. The principal utility is the capacity to evaluate the cerebrovascular reserve, thereby elucidating autoregulatory functioning. In CVR, CO2 gas challenge is the most prevalent method, which elicits a vascular response by alterations in inspired CO2 concentrations. While several systems have been proposed in the literature, only a limited number have been devised to operate in tandem with mechanical ventilation, thus constraining the majority CVR investigations to spontaneously breathing individuals. We have developed a new method, denoted Additional CO2, designed to enable CO2 challenge in ventilators. The central idea is the introduction of an additional flow of highly concentrated CO2 into the respiratory circuit, as opposed to administration of the entire gas mixture from a reservoir. By monitoring the main respiratory gas flow emanating from the ventilator, the CO2 concentration in the inspired gas can be manipulated by adjusting the proportion of additional CO2. We evaluated the efficacy of this approach in (1) a ventilator coupled with a test lung and (2) in spontaneously breathing healthy subjects. The method was evaluated by assessment of the precision in attaining target inspired CO2 levels and examination of its performance within a magnetic resonance imaging environment. Our investigations revealed that the Additional CO2 method consistently achieved a high degree of accuracy in reaching target inspired CO2 levels in both mechanical ventilation and spontaneous breathing. We anticipate that these findings will lay the groundwork for a broader implementation of CVR assessments in mechanically ventilated patients.

Effect of multidisciplinary refined time management combined with organized stroke management on the efficacy of intravenous thrombolysis in patients with acute ischemic stroke

This study aims to investigate the effects of multidisciplinary refined time management combined with organized stroke management in intravenous thrombolysis on patients with acute ischemic stroke. 226 acute ischemic stroke patients treated with intravenous thrombolysiswere selected for retrospective analysis. A Control group participants underwent organized stroke management, whereas study group participants underwent multidisciplinary refined time management based on the control group. The study group responded to intravenous thrombolysis for 24 hours at an overall rate of 92.92%, significantly higher than 79.65% in the control group (p &lt; 0.05). The time from onset to emergency, time for National Institute of Health Stroke Scale (NIHSS) scoring by emergency doctors, consultation time for neurologists, judgement time for head computed tomography (CT), interpretation time for examination results, communication time with family members to sign the consent form, and time from admission to medication in the study group were significantly shorter than that in control group (p &lt; 0.05). The incidence of hemorrhagic transformation, six-month mortality and six-month rehospitalization rate in the study group were significantly lower than those in the control group (p &lt; 0.05). Before thrombolysis, cerebrovascular reserve function and neurological function indexes in both groups were improved, and there was significant difference before and after thrombolysis in this group (p &gt; 0.05); After thrombolysis, mean blood flow velocity (MFV) and breath-holding index (BHI) in the study group were significantly higher than those in the control group (p &lt; 0.05); pulsatility index (PI) was lower than that in the control group, showing a significant difference (p &lt; 0.05); Serum nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) were significantly higher than those in the control group (p &lt; 0.05). Multidisciplinary refined time management combined with organized stroke management can improve the effect of intravenous thrombolysis in acute ischemic stroke.

The ivy sign as a radiological marker for follow-up of postoperative cerebral perfusion status in adult moyamoya disease.

Little is known about the relationship between postoperative changes in cerebral perfusion and the ivy sign representing leptomeningeal collateral burden in moyamoya disease (MMD). This study aimed to investigate the usefulness of the ivy sign in evaluating cerebral perfusion status following bypass surgery in patients with adult MMD. Two hundred thirty-three hemispheres in 192 patients with adult MMD undergoing combined bypass between 2010 and 2018 were retrospectively enrolled. The ivy sign was represented as the ivy score on FLAIR MRI in each territory of the anterior, middle, and posterior cerebral arteries. Ivy scores, as well as clinical and hemodynamic states on SPECT, were semiquantitatively compared both preoperatively and at 6 months after surgery. Clinical status improved at 6 months after surgery (p < 0.01). On average, ivy scores in whole and individual territories were decreased at 6 months (all p values < 0.01). Cerebral blood flow (CBF) postoperatively improved in three individual vascular territories (all p values ≤ 0.03) except for the posterior cerebral artery territory (PCAt), and cerebrovascular reserve (CVR) improved in those areas (all p values ≤ 0.04) except for the PCAt. Postoperative changes in ivy scores and CBF were inversely correlated in all territories (p ≤ 0.02), except for the PCAt. Furthermore, changes in ivy scores and CVR were only correlated in the posterior half of the middle cerebral artery territory (p = 0.01). The ivy sign was significantly decreased after bypass surgery, which was well correlated with postoperative hemodynamic improvement in the anterior circulation territories. The ivy sign is believed to be a useful radiological marker for postoperative follow-up of cerebral perfusion status.

Exposure to passive heat and cold stress differentially modulates cerebrovascular-CO2 responsiveness.

Heat and cold stress influence cerebral blood flow (CBF) regulatory factors (e.g., arterial CO2 partial pressure). However, it is unclear whether the CBF response to a CO2 stimulus (i.e., cerebrovascular-CO2 responsiveness) is maintained under different thermal conditions. This study aimed to compare cerebrovascular-CO2 responsiveness between normothermia, passive heat, and cold stress conditions. Sixteen participants (8 females; 25 ± 7 yr) completed two experimental sessions (randomized) comprising normothermic and either passive heat or cold stress conditions. Middle and posterior cerebral artery velocity (MCAv, PCAv) were measured during rest, hypercapnia (5% CO2 inhalation), and hypocapnia (voluntary hyperventilation to an end-tidal CO2 of 30 mmHg). The linear slope of the cerebral blood velocity (CBv) response to changing end-tidal CO2 was calculated to measure cerebrovascular-CO2 responsiveness, and cerebrovascular conductance (CVC) was used to examine responsiveness independent of blood pressure. CBv-CVC-CO2 responsiveness to hypocapnia was greater during heat stress compared with cold stress (MCA: +0.05 ± 0.08 cm/s/mmHg/mmHg, P = 0.04; PCA: +0.02 ± 0.02 cm/s/mmHg/mmHg, P = 0.002). CBv-CO2 responsiveness to hypercapnia decreased during heat stress (MCA: -0.67 ± 0.89 cm/s/mmHg, P = 0.02; PCA: -0.64 ± 0.62 cm/s/mmHg; P = 0.01) and increased during cold stress (MCA: +0.98 ± 1.33 cm/s/mmHg, P = 0.03; PCA: +1.00 ± 0.82 cm/s/mmHg; P = 0.01) compared with normothermia. However, CBv-CVC-CO2 responsiveness to hypercapnia was not different between thermal conditions (P > 0.08). Overall, passive heat, but not cold, stress challenges the maintenance of cerebral perfusion. A greater cerebrovascular responsiveness to hypocapnia during heat stress likely reduces an already impaired cerebrovascular reserve capacity and may contribute to adverse events (e.g., syncope).NEW & NOTEWORTHY This study demonstrates that thermoregulatory-driven perfusion pressure changes, from either cold or heat stress, impact cerebrovascular responsiveness to hypercapnia. Compared with cold stress, heat stress poses a greater challenge to the maintenance of cerebral perfusion during hypocapnia, challenging cerebrovascular reserve capacity while increasing cerebrovascular-CO2 responsiveness. This likely exacerbates cerebral hypoperfusion during heat stress since hyperthermia-induced hyperventilation results in hypocapnia. No regional differences in middle and posterior cerebral artery responsiveness were found with thermal stress.

Abstract 17490: Impaired Cerebrovascular Oxygen Delivery, Reserve, and Metabolism in Adult Fontan Patients

Introduction: Patients with univentricular hearts undergo a three-stage surgical palliation, culminating in total caval-pulmonary connection (Fontan procedure), maximizing delivery of oxygenated blood to the systemic circulation. Prior brain research in this population has highlighted genetic predisposition, in-utero oxygen delivery, surgical insults, and pre-Fontan cyanosis as possible mechanisms of brain injury, but none have examined the impact of the Fontan repair on brain hemodynamics. Study Purpose: To determine the sufficiency of brain O 2 delivery, cerebrovascular reserve (CVR), brain O 2 extraction fraction (OEF), and cerebral metabolic rate of O 2 (CMRO 2 ) in adult Fontan patients, compared to permeability-surface area (PS) of blood brain barrier (BBB) integrity to water, and endothelin levels. Hypothesis: We hypothesized that brain O 2 delivery, CVR, PS, and CMRO 2 would be decreased in Fontan patients, proportional to endothelin levels, an established surrogate for low cardiac output. Methods: We have enrolled 35 Fontan patients (age 20.8 ± 2.5 years, 21M) and 24 control subjects (age 23.4 ± 4.8 years, 9M) to undergo brain MRI, excluding all subjects with known stroke, seizure, or genetic abnormalities. We collected total cerebral blood flow (CBF), OEF, CVR, and PS using 3T MRI. Results: Table 1 summarizes differences in O 2 delivery, CBF, OEF, CMRO 2 , CVR, PS, and endothelin levels in the study cohort. O 2 delivery, CBF, CVR, and CMRO 2 were decreased in Fontan patients; OEF and PS were not different. Endothelin was increased but uncorrelated with the brain metrics. CMRO 2 was correlated with PS (r 2 = 0.19, p&lt;0.001). Conclusion: Adult survivors of Fontan palliation have decreased brain O 2 delivery and reserve, without compensatory OEF increases, leading to lower CMRO 2 . Decreased CMRO 2 was associated with decreased PS, but not endothelin, suggesting microvascular dysfunction rather than low cardiac output as the fundamental etiology.

Cerebral hemodynamics and oxygenation in adult patients with sickle cell disease after stem cell transplantation.

Sickle cell disease (SCD) is characterized by chronic hemolytic anemia associated with impaired cerebral hemodynamics and oxygen metabolism. Hematopoietic stem cell transplantation (HSCT) is currently the only curative treatment for patients with SCD. Whereas normalization of hemoglobin levels and hemolysis markers has been reported after HSCT, its effects on cerebral perfusion and oxygenation in adult SCD patients remain largely unexplored. This study investigated the effects of HSCT on cerebral blood flow (CBF), oxygen delivery, cerebrovascular reserve (CVR), oxygen extraction fraction (OEF), and cerebral metabolic rate of oxygen (CMRO2 ) in 17 adult SCD patients (mean age: 25.0 ± 8.0, 6 females) before and after HSCT and 10 healthy ethnicity-matched controls (mean age: 28.0 ± 8.8, 6 females) using MRI. For the CVR assessment, perfusion scans were performed before and after acetazolamide as a vasodilatory stimulus. Following HSCT, gray and white matter (GM and WM) CBF decreased (p < .01), while GM and WM CVR increased (p < .01) compared with the baseline measures. OEF and CMRO2 also increased towards levels in healthy controls (p < .01). The normalization of cerebral perfusion and oxygen metabolism corresponded with a significant increase in hemoglobin levels and decreases in reticulocytes, total bilirubin, and LDH as markers of hemolysis (p < .01). This study shows that HSCT results in the normalization of cerebral perfusion and oxygen metabolism, even in adult patients with SCD. Future follow-up MRI scans will determine whether the observed normalization of cerebral hemodynamics and oxygen metabolism prevents new silent cerebral infarcts.

Transient susceptibility imaging as a measure of hemodynamic compromise: A pilot study

Background and purposeThe purpose of this study was to test the hypothesis that hemodynamically compromised brains exhibit transient changes in magnetic susceptibility throughout the cardiac cycle, and to model these changes using Linear System Theory to extract an index that reflects cerebrovascular reserve. Materials and methodsEleven patients with angiographically-confirmed intracranial atherosclerotic disease with >50% stenosis were imaged with susceptibility weighted, cardiac-gated single shot images of cerebral Oxygen Extraction Fraction (OEF) at different timepoints of the cardiac cycle. Cardiac gating of the OEF acquisition allowed interrogation of oxygenated blood and the detection of changes throughout the cardiac cycle. Independent component analysis (ICA) of raw k-space data across the cardiac phase allowed MRI signal decomposition into dynamic and static components for image reconstruction. An asymmetry index score of the resultant parametric images were compared to test the hypothesis that variation in hemoglobin-induced susceptibility across the cardiac cycle indeed reflects pathophysiology of cerebrovascular disease. A mathematical model was derived to parameterize physiologic changes induced by the presence of a hemodynamically significant stenosis in the brain as a tissue impulse response parameter (β). ResultsOEF was elevated in the affected hemisphere (50.34 ± 12.13% vs 46.93 ± 12.34%), but failed to reach statistical significance (p < .0796). Transient changes in the OEF signal showed significant distinction between healthy and compromised tissue (0.56 ± 0.067 vs 0.44 ± 0.067, p < .019)). The derived tissue impulse response function was found to be significant as well (10.72 ± 3.48 10−3 ms−1, 9.69 ± 3.51 10−3 ms−1; p < .037). ConclusionIn this pilot study, we found transient OEF and β to be significant predictors of hemispheric compromise.

Imaging methods in assessing the surveillance of type 2 diabetes mellitus for cerebrovascular reserve and brain disease in patients with hemodynamically significant carotid stenosis

Introduction. Type 2 diabetes is the most common form of endocrine disease. Diabetes is a well-established risk factor for stroke. Carotid endarterectomy (CEE) is the main method of preventing a serious complication of stroke in patients with carotid stenosis. Consequently, the assess of type 2 diabetes on the results of CEE is an urgent problem of angiosurgery.Aim: To assess effect of type 2 diabetes on cerebrovascular reserve capacity and brain structure in patients with carotid atherosclerosis by ultrasound and magnetic resonance diagnostic.Material and Methods. 44 patients with hemodynamically significant stenosis of the internal carotid arteries (ICA), who underwent ultrasound and magnetic resonance examinations of the carotid arteries at the pre- and postoperative stages were included in this study. Two groups were formed: group I (n =15) – with a verified diagnosis of type 2 diabetes, group II (n = 29) – without diabetes. To assess the cerebrovascular reserve, functional hypercapnic and hyperoxic tests were performed.Results. The analysis of the results showed statistically significant differences in the ICA blood flow in both groups. Intergroup comparison before surgery in the middle cerebral artery on the side of hemodynamically significant stenosis revealed a statistically significant difference in pulsation and peripheral resistance index. In the common carotid arteries on both sides, significant intergroup differences were found in the velocity parameters of blood flow after the CEE operation. The reactivity index in patients with surgical stenosis with type 2 diabetes in the hyperoxic test was statistically significantly different on the side of the stenosis compared to the same indicator in the group without diabetes. There were no statistically significant differences in the hypercapnic test. The value of reactivity index indicates a negative or paradoxical reaction.Conclusion. The use of simple and accessible functional tests to assess cerebrovascular reserve, plaque structure and changes in the brain in patients with type 2 diabetes at the stage of preoperative preparation according to ultrasound and MRI studies allows us to correct the treatment and subsequent protection of the brain at the stage of surgery to prevent possible complications.

Memory, Executive, and Intellectual Functions in Adults with Moyamoya Disease

Cognitive function can decline in adults with moyamoya disease (MMD). Memory, which is an essential but complex and multifaceted function, underpins executive and intellectual functions. However, the relationship between memory and executive or intellectual functions in adults with MMD has not been well studied. The relationship between memory and cerebral blood flow has also not been elucidated. This study investigated correlations between memory, executive function, and intellectual function, and associations between cerebral blood flow and memory in adults with MMD. Memory, executive function, and intellectual function were assessed using the Wechsler Memory Scale-Revised (WMS-R), Frontal Assessment Battery (FAB), and Wechsler Adult Intelligence Scale (WAIS) third or fourth edition, respectively, in 31 adults with MMD. Cerebral blood flow was measured with iodine 123I-iodoamphetamine single-photon emission computed tomography. WMS-R scores correlated significantly with total FAB and WAIS scores before and after revascularization. Cerebral blood flow in the left posterior cerebral artery territory correlated positively with WMS-R and WAIS scores pre- and postoperatively. Postoperative cerebrovascular reserves of the right cerebellum, pons, and vermis were positively associated with visual memory, and postoperative cerebrovascular reserve of the pons was also associated with general memory. Memory function correlates with executive and intellectual functions in adults with MMD. The FAB, which requires about 10min to administer, might be useful to screen for memory dysfunction. Memory might be vulnerable to hypoperfusion in the posterior cerebral artery territory among adults with MMD. Postoperative cerebrovascular reserve might help predict memory dysfunction in adults with MMD.

Short- and Long-Term MRI Assessed Hemodynamic Changes in Pediatric Moyamoya Patients After Revascularization.

Cerebrovascular reserve (CVR) reflects the capacity of cerebral blood flow (CBF) to change following a vasodilation challenge. Decreased CVR is associated with a higher stroke risk in patients with cerebrovascular diseases. While revascularization can improve CVR and reduce this risk in adult patients with vasculopathy such as those with Moyamoya disease, its impact on hemodynamics in pediatric patients remains to be elucidated. Arterial spin labeling (ASL) is a quantitative MRI technique that can measure CBF, CVR, and arterial transit time (ATT) non-invasively. To investigate the short- and long-term changes in hemodynamics after bypass surgeries in patients with Moyamoya disease. Longitudinal. Forty-six patients (11 months-18 years, 28 females) with Moyamoya disease. 3-T, single- and multi-delay ASL, T1-weighted, T2-FLAIR, 3D MRA. Imaging was performed 2 weeks before and 1 week and 6 months after surgical intervention. Acetazolamide was employed to induce vasodilation during the imaging procedure. CBF and ATT were measured by fitting the ASL data to the general kinetic model. CVR was computed as the percentage change in CBF. The mean CBF, ATT, and CVR values were measured in the regions affected by vasculopathy. Pre- and post-revascularization CVR, CBF, and ATT were compared for different regions of the brain. P-values <0.05 were considered statistically significant. ASL-derived CBF in flow territories affected by vasculopathy significantly increased after bypass by 41 ± 31% within a week. At 6 months, CBF significantly increased by 51 ± 34%, CVR increased by 68 ± 33%, and ATT was significantly reduced by 6.6 ± 2.9%. There may be short- and long-term improvement in the hemodynamic parameters of pediatric Moyamoya patients after bypass surgery. 4 TECHNICAL EFFICACY: Stage 2.

The Early Postoperative Course of Cognitive Function and Preoperative Cerebrovascular Reserve.

Patients with severe steno-occlusive disease of a main cerebral artery without causative lesions on magnetic resonance imaging (MRI) often develop cognitive impairment. However, the effects of revascularization surgery and the source of the cognitive impairment remain unclear. Therefore, we investigated the early postoperative course of cognitive function and its association with cerebral blood flow (CBF), cerebrovascular reserve (CVR), white matter disease (WMD), lacunar infarction, and cerebrovascular risk factors. Cognitive function was examined using neurobehavioral cognitive status examination (COGNISTAT) in 52 patients with steno-occlusive disease of a main cerebral artery before and at 6 months after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis. We examined how cognition changed before and at 1, 3, and 6 months after STA-MCA anastomosis in 27 of 52 patients. CVR and CBF were calculated from 123I-N-isopropyl-p-iodoamphetamine single photon emission computed tomography, in addition to other cerebrovascular risk factors in 34 of 52 patients. Cerebral infarction and WMD (periventricular hyperintensity [PVH] and deep subcortical white matter hyperintensity) were also evaluated preoperatively by MRI. COGNISTAT scores improved at 1 month after STA-MCA anastomosis in patients with severe steno-occlusive disease of a main cerebral artery. Multiple stepwise regression analysis revealed that CVR (regression coefficient = -2.237, p = 0.0020) and PVH (regression coefficient = 2.364, p = 0.0029) were the best predictors of postoperative improvement in COGNISTAT scores (R 2 = 0.415; p = 0.0017). Cognitive function improves in relation to preoperative CVR and PVH early after STA-MCA anastomosis in patients with steno-occlusive disease of a main cerebral artery.