Cerebral Blood Flow Asymmetry Research Articles

Comparison of Perfusion Imaging Definitions of the No-Reflow Phenomenon after Thrombectomy-What Is the Best Perfusion Imaging Definition?

We performed an external validation of 4 existing published definitions of no-reflow in thrombectomy patients with extended Thrombolysis in Cerebral Infarction scale 2c to 3 (eTICI2c-3) angiographic reperfusion who underwent 24-hour perfusion imaging from 2 international randomized controlled trials (EXTEND-IA TNK part-1 and 2) and a multicenter prospective observational study. Receiver-operating-characteristic and Bayesian-information-criterion (BIC) analyses were performed with the outcome variable being dependent-or-dead at 90-days (modified Rankin Score [mRS] ≥3). Of 131 patients analyzed, the prevalence of no-reflow significantly varied between definitions (0.8-22.1%; p < 0.001). There was poor agreement between definitions (kappa 5/6 comparisons <0.212). Among patients with no-reflow according to at least 1 definition, there were significant differences between definitions in the intralesional interside differences in cerebral blood flow (CBF) (p = 0.006), cerebral blood volume (CBV) (p < 0.001), and mean-transit-time (MTT) (p = 0.005). No-reflow defined by 3 definitions was associated with mRS ≥3 at 90 days. The definition of >15% CBV or CBF asymmetry was the only definition that improved model fit on BIC analysis (ΔBIC = -8.105) and demonstrated an association between no-reflow and clinical outcome among patients with eTICI3 reperfusion. Existing imaging definitions of no-reflow varied significantly in prevalence and post-treatment perfusion imaging profile, potentially explaining the variable prevalence of no-reflow reported in literature. The definition of >15% CBV or CBF asymmetry best discriminated for functional outcome at 90 days, including patients with eTICI3 reperfusion. ANN NEUROL 2024;96:1104-1114.

Enhancing the Diagnostic Utility of ASL Imaging in Temporal Lobe Epilepsy through FlowGAN: An ASL to PET Image Translation Framework.

Positron Emission Tomography (PET) using fluorodeoxyglucose (FDG-PET) is a standard imaging modality for detecting areas of hypometabolism associated with the seizure onset zone (SOZ) in temporal lobe epilepsy (TLE). However, FDG-PET is costly and involves the use of a radioactive tracer. Arterial Spin Labeling (ASL) offers an MRI-based quantification of cerebral blood flow (CBF) that could also help localize the SOZ, but its performance in doing so, relative to FDG-PET, is limited. In this study, we seek to improve ASL's diagnostic performance by developing a deep learning framework for synthesizing FDG-PET-like images from ASL and structural MRI inputs. We included 68 epilepsy patients, out of which 36 had well lateralized TLE. We compared the coupling between FDG-PET and ASL CBF values in different brain regions, as well as the asymmetry of these values across the brain. We additionally assessed each modality's ability to lateralize the SOZ across brain regions. Using our paired PET-ASL data, we developed FlowGAN, a generative adversarial neural network (GAN) that synthesizes PET-like images from ASL and T1-weighted MRI inputs. We tested our synthetic PET images against the actual PET images of subjects to assess their ability to reproduce clinically meaningful hypometabolism and asymmetries in TLE. We found variable coupling between PET and ASL CBF values across brain regions. PET and ASL had high coupling in neocortical temporal and frontal brain regions (Spearman's r > 0.30, p < 0.05) but low coupling in mesial temporal structures (Spearman's r < 0.30, p > 0.05). Both whole brain PET and ASL CBF asymmetry values provided good separability between left and right TLE subjects, but PET (AUC = 0.96, 95% CI: [0.88, 1.00]) outperformed ASL (AUC = 0.81; 95% CI: [0.65, 0.96]). FlowGAN-generated images demonstrated high structural similarity to actual PET images (SSIM = 0.85). Globally, asymmetry values were better correlated between synthetic PET and original PET than between ASL CBF and original PET, with a mean correlation increase of 0.15 (95% CI: [0.07, 0.24], p<0.001, Cohen's d = 0.91). Furthermore, regions that had poor ASL-PET correlation (e.g. mesial temporal structures) showed the greatest improvement with synthetic PET images. FlowGAN improves ASL's diagnostic performance, generating synthetic PET images that closely mimic actual FDG-PET in depicting hypometabolism associated with TLE. This approach could improve non-invasive SOZ localization, offering a promising tool for epilepsy presurgical assessment. It potentially broadens the applicability of ASL in clinical practice and could reduce reliance on FDG-PET for epilepsy and other neurological disorders.

Brain responses to repetition-based rule-learning do not exhibit sex differences: an aggregated analysis of infant fNIRS studies

Studies have repeatedly shown sex differences in some areas of language development, typically with an advantage for female over male children. However, the tested samples are typically small and the effects do not always replicate. Here, we used a meta-analytic approach to address this issue in a larger sample, combining seven fNIRS studies on the neural correlates of repetition- and non-repetition-based rule learning in newborns and 6-month-old infants. The ability to extract structural regularities from the speech input is fundamental for language development, it is therefore highly relevant to understand whether this ability shows sex differences. The meta-analysis tested the effect of Sex, as well as of other moderators on infants’ hemodynamic responses to repetition-based (e.g. ABB: “mubaba”) and non-repetition-based (e.g. ABC: “mubage”) sequences in both anatomically and functionally defined regions of interests. Our analyses did not reveal any sex differences at birth or at 6 months, suggesting that the ability to encode these regularities is robust across sexes. Interestingly, the meta-analysis revealed other moderator effects. Thus in newborns, we found a greater involvement of the bilateral temporal areas compared to the frontal areas for both repetition and non-repetition sequences. Further, non-repetition sequences elicited greater responses in 6-month-olds than in newborns, especially in the bilateral frontal areas. When analyzing functional clusters of HbR timetraces, we found that a larger right-left asymmetry for newborn boys in brain responses compared to girls, which may be interpreted in terms of a larger right-left asymmetry in cerebral blood flow in boys than in girls early in life. We conclude that extracting repetition-based regularities from speech is a robust ability with a well-defined neural substrate present from birth and it does not exhibit sex differences.

АНАЛИЗ РЕОЭНЦЕФАЛОГРАФИЧЕСКОГО ИССЛЕДОВАНИЯ МЕЖПОЛУШАРНОЙ АСИММЕТРИИ МОЗГОВОГО КРОВОТОКА У ЗДОРОВЫХ И УМСТВЕННО ОТСТАЛЫХ ДЕТЕЙ 8-11 ЛЕТ

The features of functional organization of hemodynamic processes in brain basins of healthy children and children with mild mental retardation, depending on the nature of asymmetry and gradient of cerebral blood flow, were studied. The study involved 131 children aged from 8 to 11 years. Of them, 73 were healthy with normal physical and mental development, and 58 children - with mild mental retardation. The study was conducted to determine what kind of sports and physical activity allow children with mental retardation to engage in activities. To study the functional interhemispheric asymmetry of cerebral blood flow in the studied groups of children, the technique of rheoencephalography was used. The article presents the results of empirical studies of rheoencephalography parameters of the brain among healthy children and those with mild mental retardation. The parameters of cerebral blood circulation of healthy children and children with mental retardation aged 8-11 years, reflecting the state of different parts of the cerebral vascular system, were studied. We also analyzed and compared age-related changes in the functional organization of hemodynamic processes in healthy children aged 8-11 years and in children diagnosed with mental retardation.

Lateralization of interictal temporal lobe hypoperfusion in lesional and non-lesional temporal lobe epilepsy using arterial spin labeling MRI

PurposeNon-invasive imaging studies play a critical role in the presurgical evaluation of patients with drug-resistant temporal lobe epilepsy (TLE), particularly in helping to lateralize the seizure focus. Arterial Spin Labeling (ASL) MRI has been widely used to non-invasively study cerebral blood flow (CBF), with somewhat variable interictal alterations reported in TLE. Here, we compare temporal lobe subregional interictal perfusion and symmetry in lesional (MRI+) and non-lesional (MRI-) TLE compared to healthy volunteers (HVs). MethodsTwenty TLE patients (9 MRI+, 11 MRI-) and 14 HVs under went 3 T Pseudo-Continuous ASL MRI through an epilepsy imaging research protocol at the NIH Clinical Center. We compared normalized CBF and absolute asymmetry indices in multiple temporal lobe subregions. ResultsCompared to HVs, both MRI+ and MRI- TLE groups demonstrated significant ipsilateral mesial and lateral temporal hypoperfusion, specifically in the hippocampal and anterior temporal neocortical subregions, with additional hypoperfusion in the ipsilateral parahippocampal gyrus in the MRI+ and contralateral hippocampus in the MRI- TLE groups. Contralateral to the seizure focus, there was significant relative hypoperfusion in multiple subregions in the MRI- compared to the MRI+ TLE groups. The MRI+ group therefore had significantly greater asymmetry across multiple temporal subregions compared to the MRI- TLE and HV groups. No significant differences in asymmetry were found between the MRI- TLE and HV groups. ConclusionWe found a similar extent of interictal ipsilateral temporal hypoperfusion in MRI+ and MRI- TLE. However, significantly increased asymmetries were found only in the MRI+ group due to differences in perfusion contralateral to the seizure focus between the patient groups. The lack of asymmetry in the MRI- group may negatively impact the utility of interictal ASL for seizure focus lateralization in this patient population.

Quantitative association of cerebral blood flow, relaxation times and proton density in young and middle-aged primary insomnia patients: A prospective study using three-dimensional arterial spin labeling and synthetic magnetic resonance imaging.

To quantitatively measure the T1 value, T2 value, proton density (PD) value, and cerebral blood flow (CBF) in young and middle-aged primary insomnia (PI) patients, and analyze the correlations between relaxation times, PD, and CBF to explore potential brain changes. Cranial magnetic resonance (MR) images of 44 PI patients and 30 healthy subjects were prospectively collected for analysis. The T1, T2, PD, and CBF values of the frontal lobe, parietal lobe, temporal lobe, and occipital lobe were independently measured using three-dimensional arterial spin labeling (3D-ASL), synthetic magnetic resonance imaging (syMRI) and a whole-brain automatic segmentation method. The differences of these imaging indices were compared between PI patients and healthy subjects. Follow-up MR images were obtained from PI patients after 6 months to compare with pre-treatment images. The Wilcoxon signed rank test and Spearman rank were used for statistical analysis. Bilateral CBF asymmetry was observed in 38 patients, with significant differences in both the T2 value and CBF between the four lobes of the brain (p < 0.01). However, no significant difference was found in the T1 and PD values between the bilateral lobes. A negative correlation was found between CBF and T2 values in the right four lobes of patients with primary insomnia (PI). During follow-up examinations, five PI patients showed a disappearance of insomnia symptoms and a decrease in CBF in both brain lobes. Insomnia symptoms may be associated with high CBF, and most PI patients have higher CBF and lower T2 values in the right cerebral hemispheres. The right hemisphere appears to play a critical role in the pathophysiology of PI. The 3D-ASL and syMRI technologies can provide a quantitative imaging basis for investigating the brain conditions and changes in young and middle-aged PI patients.

A Comparative Study of Regional Cerebral Blood Flow Asymmetry Index in Stroke Patients with or without Poststroke Depression Using 99m Tc-ECD Single-Photon Emission Computed Tomography.

Introduction Stroke is a major cause of death and disability around the globe. The development of depression following a stroke further increases the disability and impairs functional recovery. In recent decades, despite the advancement in structural and nuclear medicine imaging, the pathophysiologic basis of poststroke depression (PSD) is not well understood. Etiopathogenesis of PSD is multifactorial and afflictions of the frontal lobe, hippocampus, limbic region, and basal ganglia projections are implicated. Aim The aim of this study was to assess the regional cerebral blood flow (rCBF) using 99m Tc-ethyl cysteinate dimer single-photon emission computed tomography (SPECT) in patients with (PSD + ) or without PSD (PSD–). Materials and Methods To evaluate the hemispheric asymmetry, the percentage of asymmetry index (AI) was calculated for frontal, temporal, parietal, occipital, putamen, caudate, and thalamic regions of brain and compared between PSD+ and PSD–. The correlation between AIs over the different brain regions was also established in patients of PSD+ and PSD–. Our study cohort included 122 patients between 6 weeks and 1 year of stroke. Depression was present in 52 (42.6%) patients, assessed by hospital anxiety and depression scale (HADS) and general health questionnaire-28 items (GHQ-28) scale. The 28 patients with PSD+ and 18 PSD– gave consent for SPECT study. Results Our results are based on 46 patients who underwent SPECT study. In patients with PSD+ and PSD–, the HADS and GHQ-28 scores were 8.93 ± 2.77 vs. 3.94 ± 2.15 ( p = 0.001) and 40.96 ± 9.48 vs. 17.72 ± 5.38 ( p = 0.001), respectively. A significant difference in rCBF AI was found in the temporal lobe ( p = 0.03) between patients of PSD+ and PSD–. On logistic regression analysis, the odds ratio of rCBF AI for temporal lobe was 0.89 (95% confidence interval [CI]: 0.80–0.99; p = 0.04) and caudate nucleus was 0.85 (95% CI: 0.73–0.98; p = 0.03), which were statistically significant. PSD correlated with AI in temporal region ( r = –0.03; p = 0.03) but did not show significant correlation with other regions of brain between PSD+ and PSD–. Conclusion The presence of temporal lobe rCBF AI on SPECT is significantly associated with PSD. This may reflect the dysfunction of the limbic system and contribute to the occurrence of PSD.

Arterial spin labeling imaging for the detection of cerebral blood flow asymmetry in patients with corticobasal syndrome.

Corticobasal syndrome (CBS) and Parkinson's disease (PD) both present with asymmetrical extrapyramidal symptoms, often leading to a diagnostic dilemma. Patients with CBS frequently show cerebral blood flow (CBF) asymmetry alongside asymmetrical cortical atrophy. This study aimed to evaluate the clinical utility of arterial spin labeling (ASL) magnetic resonance imaging (MRI) to detect CBF asymmetry in patients with CBS. We retrospectively investigated asymmetries of regional CBF and cortical volume, measured using ASL and T1-weighted MRI, in 13 patients with CBS and 22 age-matched patients with PD. Regional CBF and cortical volume values were derived from nine brain regions on each side. CBF and volume asymmetries were calculated as %difference in each region, respectively. CBF asymmetry showed significantly greater differences in seven of nine regions, such as the perirolandic area (- 8.7% vs. - 1.4%, p < 0.001) and parietal cortex (- 9.7% vs. - 1.3%, p < 0.001) in patients with CBS compared with patients with PD. In contrast, significant differences in volume asymmetry were observed in three regions included within the seven regions showing CBF asymmetry, which indicated that CBF asymmetry has greater sensitivity than volume asymmetry to detect asymmetricity in CBS. ASL imaging showed significant CBF asymmetry in a wider range of brain regions in patients with CBS, which suggests that noninvasive MRI with ASL imaging is a promising tool for the diagnosis of CBS, with advantages that include the simultaneous evaluation of asymmetrical hypoperfusion in addition to focal atrophy.

Cerebral arterial architectonics and CFD simulation in mice with type 1 diabetes mellitus of different duration

Type 1 diabetes is a chronic autoimmune disease that affects tens of millions of people. Diabetes mellitus is one of the strongest factors in the development of cerebrovascular diseases. In this study we used NOD.CB17 Prkdcscid mice and the pharmacological model of type 1 diabetes mellitus of different duration to study changes in the cerebral vasculature. We used two combined approaches using magnetic resonance angiography both steady and transient CFD blood flow modeling. We identified the influence of type 1 diabetes on the architectonics and hemodynamics of the large blood vessels of the brain as the disease progresses. For the first time, we detected a statistically significant change in angioarchitectonics (the angles between the vessels of the circle of Willis, cross-sections areas of vessels) and hemodynamic (maximum blood flow rate, hydraulic resistance) in animals with diabetes duration of 2 months, that is manifested by the development of asymmetry of cerebral blood flow. The result shows the negative effect of diabetes on cerebral circulation as well as the practicability of CFD modeling. This may be of extensive interest, in pharmacological and preclinical studies.

Prediction of post-stroke depression with spect-derived cerebral blood flow asymmetry index

Prediction of post-stroke depression with spect-derived cerebral blood flow asymmetry index

Can interhemispheric desynchronization of cerebral blood flow anticipate upcoming vasospasm in aneurysmal subarachnoid haemorrhage patients?

BackgroundAsymmetry of cerebral autoregulation (CA) was demonstrated in patients after aneurysmal subarachnoid haemorrhage (aSAH). A classical method for CA assessment requires simultaneous measurement of both arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV). In this study, we have proposed a cerebral blood flow asymmetry index based only on CBFV and analysed its association with the occurrence of vasospasm after aSAH. New methodThe phase shifts (PS) between slow oscillations in left and right CBFV (side-to-side PS) and between ABP and CBFV (CBFV–ABP PS) were estimated using multichannel matching pursuit (MMP) and cross-spectral analysis. ResultsWe retrospectively analysed data collected from 45 aSAH patients (26 with vasospasm). Data were analysed up to 7th day after aSAH unless the vasospasm was detected earlier. A progressive asymmetry, manifested by a gradual increase in side-to-side PS on consecutive days after aSAH, was observed in patients who developed vasospasm (Radj2 = 0.14, p = 0.009). In these patients, early side-to-side PS was more positive than in patients without vasospasm (2.8° ± 5.6° vs –1.7° ± 5.7°, p = 0.011). No such a difference was found in CBFV–ABP PS. Patients with positive side-to-side PS were more likely to develop vasospasm than patients with negative side-to-side PS (21/7 vs 5/12, p = 0.0047). Comparison with existing methodMMP, in contrast to the spectral approach, accounts for non-stationarity of analysed signals. MMP applied to the PS estimation reflects the cerebral blood flow asymmetry in aSAH better than the spectral analysis. ConclusionsChanges in side-to-side PS might be helpful to identify patients who are at risk of vasospasm.

Pathological factors contributing to crossed cerebellar diaschisis in cerebral gliomas: a study combining perfusion, diffusion, and structural MR imaging.

To investigate imaging features of crossed cerebellar diaschisis (CCD) in cerebral gliomas, and its underlying pathophysiological mechanisms. Thirty-three pre-surgical patients with cerebral gliomas and 33 healthy controls underwent arterial spin-labeling, diffusion tensor imaging, and high-resolution T1-weighted imaging using MRI, in order to estimate cerebral blood flow (CBF), white matter integrity, and lesion volume, respectively. Asymmetry indices of CBF in the cerebellum were used for evaluating the level of CCD in the patients. These indices were correlated with clinical variables (lesion size and position, tumor histological grade, and CBF asymmetry) and diffusion tensor imaging parameters (fractional anisotropy and number of fibers in the cortico-ponto-cerebellar pathway and across the cerebral hemispheres), respectively. The patients showed decreased CBF in the cerebellar hemisphere contralateral to the supratentorial tumor, and increased CBF asymmetry in the cerebellum (both P < 0.05). CCD levels in high-grade gliomas were higher than those of low-grade gliomas (P < 0.05). CCD levels were negatively correlated with the size of the supratentorial lesions, and positively correlated with FA asymmetry in the cerebral fibers (both P < 0.05). CCD in cerebral gliomas was specifically associated with tumor histological grade, lesion size, and white matter impairments in the hemisphere ipsilateral to the tumor. The findings implicated that observing CCD might have potential for assisting grading diagnosis of cerebral gliomas.

Cerebral blood flow changes in remitted early- and late-onset depression patients.

Abnormal cerebral blood flow (CBF) is reportedly associated with major depressive disorder (MDD). We have investigated CBF changes in early-onset depression (EOD) and late-onset depression (LOD), and their impact on cognitive function. Thirty-two remitted EOD patients, 32 remitted LOD patients, and 43 age-matched healthy controls were recruited, and the pulsed arterial spin labeling data were scanned under 3.0T MRI and processed through voxel-by-voxel statistical analysis. Compared to healthy controls, LOD patients had decreased normalized CBF in the bilateral precuneus, cuneus, right fronto-cingulate-striatal areas, and right temporal, occipital and parietal lobes, but increased normalized CBF in the left frontal and temporal cortices and the cingulate gyrus. EOD patients had decreased normalized CBF in the left cerebellum and right calcarine/lingual/fusiform gyrus, and increased normalized CBF in right angular gyrus. LOD patients displayed hemispheric asymmetry in CBF, and had more regions with abnormal CBF than EOD patients. A significant correlation between abnormal CBF and impaired cognitive function was detected in LOD patients, but not EOD patients. These results demonstrate greater CBF abnormalities in LOD patients than EOD patients, and suggest these CBF changes may be associated with progressive degradation of cognitive function in LOD patients.

Pseudo-asymmetry of cerebral blood flow in arterial spin labeling caused by unilateral fetal-type circle of Willis: Technical limitation or a way to better understanding physiological variations of cerebral perfusion and improving arterial spin labeling acquisition?

In the recently published article, “Unilateral fetal-type circle of Willis anatomy causes right-left asymmetry in cerebral blood flow with pseudo-continuous arterial spin labeling: A limitation of arterial spin labeling-based cerebral blood flow measurements?”, it was shown by the method of arterial spin labeling (ASL) that unilateral fetal-type circle of Willis could induce variation of blood flow in cerebellar and posterior cerebral artery territory. We believe that the reported observation, rather than being a limitation, gives several interesting cues for understanding the ASL sequence. In this commentary, we formulate some suggestions regarding the use of ASL in clinical practice, discuss the potential causes of the above-mentioned pseudo-asymmetry and consider future improvements of the ASL technique.

Unilateral fetal-type circle of Willis anatomy causes right–left asymmetry in cerebral blood flow with pseudo-continuous arterial spin labeling: A limitation of arterial spin labeling-based cerebral blood flow measurements?

The accuracy of cerebral blood flow measurements using pseudo-continuous arterial spin labeling can be affected by vascular factors other than cerebral blood flow, such as flow velocity and arterial transit time. We aimed to elucidate the effects of common variations in vascular anatomy of the circle of Willis on pseudo-continuous arterial spin labeling signal. In addition, we investigated whether possible differences in pseudo-continuous arterial spin labeling signal could be mediated by differences in flow velocities. Two hundred and three elderly participants underwent magnetic resonance angiography of the circle of Willis and pseudo-continuous arterial spin labeling scans. Mean pseudo-continuous arterial spin labeling-cerebral blood flow signal was calculated for the gray matter of the main cerebral flow territories. Mean cerebellar gray matter pseudo-continuous arterial spin labeling-cerebral blood flow was significantly lower in subjects having a posterior fetal circle of Willis variant with an absent P1 segment. The posterior fetal circle of Willis variants also showed a significantly higher pseudo-continuous arterial spin labeling-cerebral blood flow signal in the ipsilateral flow territory of the posterior cerebral artery. Flow velocity in the basilar artery was significantly lower in these posterior fetal circle of Willis variants. This study indicates that pseudo-continuous arterial spin labeling measurements underestimate cerebral blood flow in the posterior flow territories and cerebellum of subjects with a highly prevalent variation in circle of Willis morphology. Additionally, our data suggest that this effect is mediated by concomitant differences in flow velocity between the supplying arteries.

AGE FEATURES OF HEMISPHERIC ASYMMETRY OF CEREBRAL BLOOD FLOW IN CHILDREN WITH ATTENTION DEFICIT HYPERACTIVITY DISORDER

The article presents the features of asymmetry of cerebral blood flow determined with use of rheoencephalography of 97 boys aged 7-10 years and 56 boys aged 11-14 years with the attention deficit hyperactivity disorder. It has been found that in primary school the children showed reduction in blood filling intensity and improvement of elastic properties of blood vessels for distribution and resistance in the carotid region, increased elastic properties of blood vessels in the vertebrobasilar area on the left. Obviously, these changes in the cerebral blood flow reflected the specific characteristics of the cerebral blood flow in children with this disorder. For children at secondary school age, there is registered an increase of the blood flow intensity, the tone of large arteries and elastic properties of blood vessels for distribution and resistance in carotid and vertebrobasilar area on the left, which corresponds to the existing ideas about organization of hemodynamic processes in the brain and the role of the left-hemispheric dominance in children in ontogenesis.

Whole brain C-arm computed tomography parenchymal blood volume measurements.

C-arm flat detector computed tomography (FDCT) parenchymal blood volume (PBV) imaging in the neuro-interventional suite is a new technique for which detailed whole brain measurements have not been previously reported. This study aims to create a catalogue of PBV measurements for various anatomical regions encompassing the whole brain, using a three-dimensional volume-of-interest (3D-VOI) analysis. We acquired and analysed 30 C-arm FDCT datasets from 26 patients with aneurysmal subarachnoid haemorrhage (SAH), as part of a prospective study comparing C-arm computed tomography (CT) PBV with magnetic resonance perfusion-weighted imaging (MR-PWI). We calculated the PBV values for various brain regions with an automated analysis, using 58 pre-defined atlas-based 3D-VOIs encompassing the whole brain. VOIs partially or completely overlapping regions of magnetic resonance diffusion weighted imaging (MR-DWI) abnormality or magnetic resonance cerebral blood flow (MR-CBF) asymmetry were excluded from the analysis. Of the 30 C-arm CT PBV datasets, 14 (54%; 12 patients) had areas of restricted diffusion, the majority of which were focal. The PBV values for the cerebral cortex and cerebral white matter were 4.01 ± 0.47 (mean ± SD) and 3.01 ± 0.39 ml per 100 ml. Lobar PBV values were: frontal lobe 4.2 ± 0.8, temporal lobe 4.2 ± 0.9, parietal lobe 3.9 ± 0.7 and occipital lobe 4.3 ± 0.8 ml/100 ml. The basal ganglia and brainstem PBV values were 3.4 ± 0.7 and 4.6 ± 0.6 ml/100 ml, respectively. Compared with the typical reference cerebral blood volume (CBV) values reported in the literature for Positron Emission Tomography (PET), the PBV values were relatively high for the white matter and relatively low for the cortical grey matter. The reported catalogue of PBV values for various brain regions would be useful to inform future studies and could be used in clinical practice, when interpreting PBV maps.

Cerebral Perfusion Patterns in Transgenic Murine Models of Sickle Cell Disease As Seen By MRI Is Reflective of Their Anemia Profile and Parallels the Human Disease

Background: Sickle cell disease is an anemia disorder of the red blood cell in which hemoglobin S (HbS) undergoes polymerization and sickling under low-oxygenation conditions, leading to vaso-occlusive events. Major frequent neurological complications of SCD include ischemia and stroke leading to cognitive deficits and morbidity. Clinical observations have done little to identify the causes of stroke in SCD. Animal models of SCD, and in particular transgenic models have been useful in understanding the microvascular phenomena leading to vasculopathy. Polymerization and consequent sickling of red blood cells (RBC) under oxygen stress conditions likely result in sludging of blood and consequent vasoocclusion, at least in peripheral post-capillary tissues. Most animal studies suggest that the primary site for interaction of RBC's carrying HbSreside in the venous vasculature, yet large arterial stroke remains a significant occurrence in clinical SCD, where suggested risk factors include elevated carotid blood velocity and turbulence, cerebral blood flow asymmetry, loss of cerebrovascular reactivity and cerebral hyperemia. In particular, human cerebral hyperemia appears to be a frequent and significant finding, presumably a compensatory response to the SCD anemia.We sought to determine how closely Tg animal models of SCD mimic the cerebral findings associated with human SCD. Several models have been developed, including the NY1DD model which does not exhibit anemia, but in which sickling only occurs following a period of hypoxia, the S+S Antilles (SSAnt) model which suffers mild anemia and sickling under normal conditions, and the Berkley (BERK) which exhibits severe anemia, sickling and early mortality. We used MRI to evaluate these SCD models and compared the findings to those of WT animals.Methods: NY1DD (n=11, 2.6± 0.8 mo, HCT=0.47± 0.04), SSAnt (n=11, 3.3 ± 1.2 mo, HCT=0.43± 0.04), BERK (n=11 at 3 mo, n=5 at 10 mo, HCT=0.33± 0.03) and WT (C57bl, n=5 at 10 mo, n=4) were studied in accord with PHS and AALAC guidelines. Anesthetized (isoflurane) animals were studied with a 9.4 T MRI (Agilent, Inc., CA). MRI included assessment of perfusion (FAIR-ASL), fMRI (BOLD response to a period of hyperoxia), Diffusion Tensor Imaging (DTI), and structural imaging.Results: No differences were observed in CBF, BRHO or MD between young and old animals. Cerebral blood flow increased with severity of anemia-with BERK CBF higher than WT, NY1DD or SSAnt CBF (P < 0.0001). NY1DD and SSAnt CBF were not different, but both were higher than WT CBF (p < 0.001). Bold Response to hyperoxia indicated that BERK animals suffered the greatest oxygen debt, while NY1DD and SSAnt were not significantly worse than WT under normoxia conditions. Mean tissue diffusivity (obtained from DTI), a marker for edema and inflammation, was elevated only in BERK mice compared to WT mice (p < 0.05), while fractional anisotropy was not different between groups.Conclusion: As the degree of anemia worsens, CBF increases presumably to compensate for lower hemoglobin and reduced oxygen carrying capacity. In BERK mice, this increase in CBF is inadequate to compensate for reduced oxygen delivery, and this is indicated by an increase in the BOLD response to hyperoxia (BRHO measure). SSAnt and NY1DD animals both exhibited elevated CBF, but their BRHO was not significantly different from WT animals. This suggests that their increase in CBF was adequate to compensate for sickle induced vasoocclusion and/or mild anemia under normal oxygenation conditions. Our findings suggest that the BERK mouse may be the best model for evaluating therapeutics directed at treating the chronic anemia associated with human SCD, and for evaluating therapeutics aimed at remedying hypoxia induced oxygen radical damage. However, NY1DD or SSAnt may be better models for studying experimentally induced sickle crisis (extended durations of hypoxia), as BERK mice are to fragile to survive such perturbations. [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Features of cerebral blood flow, cardiac arrhythmias and conduction disturbances in patients with essential hypertension stage II associated with occlusive and stenotic lesions of brachiocephalic arteries.

Arterial hypertension is the most common disease of the cardiovascular system in industrially advanced countries. With the aim to determine the characteristics of cerebral blood flow, disorders of cardiac rhythm and conduction in patients with stage 2 hypertension associated with stenotic and occlusive lesions of brachiocephalic arteries, cerebral blood flow indicators were studied in 87 patients using duplex scanning of extracranial arteries and Holter ECG monitoring. It was established that linear blood flow velocity was considerably decreased in the basins of the internal and common carotid artery; cerebral blood flow asymmetry was present in the course of the internal carotid artery. Evidence-based differences in structure of arrhythmias were revealed by single and paired ventricular extrasystoles, as well as episodes of unstable ventricular tachycardia. All this indicates the progressive decrease of elasticity and tonicity of vessel walls, intensified rigidity and sinuosity of carotid arteries, more severe disorders of cardiac rhythm and conduction in case of simultaneous hypertension and atherosclerotic lesion of brachiocephalic arteries.

Asymmetry of cerebral blood flow measured with three-dimensional pseudocontinuous arterial spin-labeling mr imaging in temporal lobe epilepsy with and without mesial temporal sclerosis.

To investigate the asymmetry of quantitative cerebral blood flow (CBF) values in interictal temporal lobe epilepsy (TLE) patients with (TLE-MTS) and without (TLE-no) mesial temporal sclerosis. Twenty-six TLE patients (14 TLE-MTS/12 TLE-no) and 22 controls were studied with a three-dimensional whole-brain pseudocontinuous arterial spin-labeling technique at 3.0 Tesla. Regions of interest were placed at the bilateral hippocampal heads, amygdalas and temporal lobes to get the average regional cerebral blood flow (rCBF) and calculate asymmetry indices (AIs). Statistical parametric mapping detected the whole-brain CBF changes of the two subgroups (right-sided). AIs of the hippocampus and amygdala in TLE-MTS and AIs of hippocampus in TLE-no were significantly different versus controls (P < 0.001, P = 0.001, and P = 0.013). The lateralizing sensitivity increased to 96.154% by combining structural MRI and AIs of rCBF with optimal cutoff values. Hypoperfusion regions in the right TLE-MTS mainly clustered in the bilateral temporal lobes, frontal lobes, insular lobes, and left caudate nucleus. The right TLE-no showed hypoperfusion in the bilateral temporal lobes, frontal lobes, right insular lobe, parietal lobe, occipital lobe, and caudate nucleus. Asymmetry of CBF in the TLE-MTS and TLE-no is different and improves MRI performance in lateralizing the TLE.