rCBF Values Research Articles

CT perfusion assessment of Moyamoya syndrome before and after direct revascularization (superficial temporal artery to middle cerebral artery bypass).

To evaluate the utility of CT perfusion (CTP) for the assessment of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis in patients with Moyamoya syndrome (MMS). Twenty-four consecutive MMS patients, who underwent unilateral STA-MCA bypass surgery, received CTP before and after surgery. The relative perfusion parameter values of surgical hemispheres before treatment were compared with post-treatment values. All patients underwent CT angiography (CTA) before and after surgery in order to confirm the patency of bypass. The follow-up CTA after surgery clearly demonstrated 20 (20/24, 83.3 %) bypass arteries, whereas four (16.7 %) bypass arteries were occluded or very small. Postoperative rMTT and rTTP values (P < 0.05) of the surgical side were significantly lower than pre-operation. In patients (n = 20) with bypass patency, postoperative rCBF, rMTT and rTTP values (P < 0.05) of the surgical side were significantly improved. However, the differences of all parameters were not significant (P > 0.05) in the patients (n = 4) without bypass patency after revascularization. This study demonstrates that CTP can provide a crucial quantitative assessment of cerebral haemodynamic changes in MMS before and after STA-MCA anastomosis. Twenty-four MMS patients undergoing STA-MCA bypass received CTP pre- and post-surgery. Cerebral haemodynamics improved on the surgical side post-surgery on CTP maps. rCBF might have a better correlation with patency of the bypass artery. CTP can evaluate cerebral perfusion changes in MMS patients after cerebral revascularization.

New Regression Equation for 123I-IMP Non-invasive Cerebral Blood Flow Measurement Using the Graph Plot Method.

A graph plot (GP) method using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) has been proposed as a simple and non-invasive estimation of quantitative cerebral bloodflow (CBF). A regression equation for the GP method was estimated by the data of resting state. Therefore, the accuracy of CBF values in high flow range may be an underestimated possibility in this method.The aim of this study was to formulate a new regression equation for the GP method by the data of resting state and acetazolamide (ACZ) challenge, and to clarify the accuracy of it. The images of 26 consecutive patients who underwent both 123I-IMP chest radioisotope-angiography (RIA) and single photon emission computed tomography (SPECT) examinations were used to construct the new regression equation. Examinations of the resting state and ACZ challenge were performed in different days. All patients were analyzed by both the GP method and autoradiography (ARG) method which is the conventional examination with the one-point arterial blood sampling. A linear regression equation between the index of the input function was obtained by the GP method and CBF value of ARG. The linear regression equation based on the resting data was compared with the equation based on the resting and ACZ challenge (rest+stress) data. Goodliner correlation was obtained between the index of the input function obtained by the GP method and CBF value of the ARG method in the rest+stress state (y=2.75x+15.1, r=0.78). In contrast, correlation results between the index of the input function obtained by the GP method and CBF value of the ARG method in the resting state was expressed as y=2.28x+18.4, r=0.54 rCBF values based on the resting data was 20% underestimated in the high flow range compared with values based on the rest+stress data. The new linear regression equation for the GP method is useful for clinical study. Key words: non-invasive cerebral blood flow measurement method, graph plot (GP), autoradiography (ARG), 123I-N-isopropyl-p-iodoamphetamine (123I-IMP).

Cerebral blood flow and cognitive function in patients with metabolic syndrome: effect of antihypertensive therapy.

The aim of the study was to estimate regional cerebral blood flow (rCBF) and cognitive function in patients with metabolic syndrome (MetS) before and after antihypertensive combination therapy. The study included 24 patients with MetS (average age 52.4±1.6years). All patients underwent brain single-photon emission computed tomography with technetium-99m hexamethylpropyleneamine oxime and comprehensive neuropsychological testing before and after 6-month antihypertensive combination therapy. All patients with MetS showed lower rCBF values in all regions of the brain compared with the control group. Their parameters of attention, immediate visual memory, and mentation were lower by 25%, 22%, and 13% compared with the control group, respectively. Six-month antihypertensive combination therapy increased cerebral perfusion and improved attention, mentation, and visual memory in MetS patients.

Survival analysis in patients with newly diagnosed primary glioblastoma multiforme using pre- and post-treatment peritumoral perfusion imaging parameters.

The objective of this study was to evaluate if peritumoral (PT) perfusion parameters obtained from dynamic susceptibility weighted contrast enhanced perfusion MRI can predict overall survival (OS) and progression free survival (PFS) in patients with newly diagnosed glioblastoma multiforme (GBM). Twenty-eight newly diagnosed GBM patients, who were treated with resection followed by concurrent chemoradiation and adjuvant chemotherapy, were included in this study. Evaluated perfusion parameters were pre- and post-treatment PT relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF). Proportional hazard analysis was used to assess the relationship OS, PFS and perfusion parameters. Kaplan-Meier survival estimates and log-rank test were used to characterize and compare the patient groups with high and low perfusion parameter values in terms of OS and PFS. Pretreatment PT rCBV and rCBF were not associated with OS and PFS whereas there was statistically significant association of both posttreatment PT rCBV and rCBF with OS and posttreatment rCBV with PFS (association of PFS and posttreatment rCBF was not statistically significant). Neither the Kaplan-Meier survival estimates nor the log-rank test demonstrated any differences in OS between high and low pretreatment PT rCBV values and rCBF values; however, high and low post-treatment PT rCBV and rCBF values did demonstrate statistically significant difference in OS and PFS. Our study found posttreatment, not pretreatment, PT perfusion parameters can be used to predict OS and PFS in patients with newly diagnosed GBM.

Assesment of perfusion in glial tumors with arterial spin labeling; comparison with dynamic susceptibility contrast method

PurposeArterial spin labeling perfusion imaging (ASL-PI) is a non-invasive perfusion imaging method that can be used for evaluation and quantification of cerebral blood flow (CBF). Aim of our study was to evaluating the efficiency of ASL in histopathological grade estimation of glial tumors and comparing findings with dynamic susceptibility contrast perfusion imaging (DSC-PI) method. MethodsThis study involved 33 patients (20 high-grade and 13 low-grade gliomas). Multiphase multislice pulsed ASL MRI sequence and a first-passage gadopentetate dimeglumine T2*-weighted gradient-echo single-shot echo-planar sequence were acquired for all the patients. For each patient, perfusion relative signal intensity (rSI), CBF and relative CBF (rCBF) on ASL-PI and relative cerebral blood volume (rCBV) and relative cerebral blood flow (rCBF) values on DSC-PI were determined. The relative signal intensity of each tumor was determined as the maximal SI within the tumor divided by SI within symetric region in the contralateral hemisphere on ASL-PI. rCBV and rCBF were calculated by deconvolution of an arterial input function. Relative values of the lesions were obtained by dividing the values to the normal appearing symmetric region on the contralateral hemisphere. For statistical analysis, Mann–Whitney ranksum test was carried out. Receiver operating characteristic curve (ROC) analysis was performed to assess the relationship between the rCBF-ASL, rSI-ASL, rCBV and rCBF ratios and grade of gliomas. Their cut-off values permitting best discrimination was calculated. The correlation between rCBV, rCBF, rSI-ASL and rCBF-ASL and glioma grade was assessed using Spearman correlation analysis. ResultsThere was a statistically significant difference between low and high-grade tumors for all parameters. Correlation analyses revealed significant positive correlations between rCBV and rCBF-ASL (r=0.81, p<0.001). However correlation between rCBF and rCBF-ASL was weaker (r=0.64, p<0.001). ConclusionArterial spin labeling is an employable imaging technique for evaluating tumor perfusion non-invasively and may be useful in differentiating high and low grade gliomas.

Impaired CBF regulation and high CBF threshold contribute to the increased sensitivity of spontaneously hypertensive rats to cerebral ischemia

The correlation between temporal changes of regional cerebral blood flow (rCBF) and the severity of transient ischemic stroke in spontaneously hypertensive rats (SHR) and Wistar–Kyoto rats (WKY) was investigated using T2-, diffusion- and perfusion-weighted magnetic resonance imaging at six different time points: before and during 1h of unilateral middle cerebral artery occlusion (MCAO), 1h after reperfusion, and 1day, 4days and 7days after MCAO. rCBF values were measured in both hemispheres, and the perfusion-deficient lesion (PDL) was defined as the area of the brain with a 57% or more reduction in basal CBF. Within the PDL, regions were further refined as ischemic core (rCBF=0–6mL/100g/min), ischemic penumbra (rCBF=6–15mL/100g/min) and benign oligemia (rCBF>15mL/100g/min). SHR and WKY had identical initial volume of the PDLs (WKY: 32.52±4.08% vs. SHR: 33.95±3.68%; P>0.05) and the maximum rCBF measured within those lesions (WKY: 38.20±3.57mL/100g/min vs. SHR: 38.46±6.22mL/100g/min; P>0.05) during MCAO. However, in SHR virtually all of the PDL progressed to become the final ischemic lesion (33.02±5.41%, P>0.05), while the final ischemic lesion volume of WKY (12.62±9.19%) was significantly smaller than their original PDL (P<0.01) and similar to the ischemic core (13.13±2.96%, P>0.05). The region with the lowest range of rCBF was positively correlated with the final ischemic lesion volume (r=0.716, P<0.01). Both during ischemia and after reperfusion, rCBF in either ipsilesional and contralesional brain hemispheres of SHR could not be restored to pre-ischemic levels, and remained lower than in WKY until up to 4days after MCAO. The data suggest that impaired CBF regulation and relatively high CBF threshold for ischemia are strong contributors to the increased susceptibility of SHR to ischemic stroke.

Regional reliability of quantitative signal targeting with alternating radiofrequency (STAR) labeling of arterial regions (QUASAR).

BACKGROUND AND PURPOSEQuantitative signal targeting with alternating radiofrequency labeling of arterial regions (QUASAR) is a recent spin labeling technique that could improve the reliability of brain perfusion measurements. Although it is considered reliable for measuring gray matter as a whole, it has never been evaluated regionally. Here we assessed this regional reliability.METHODSUsing a 3-Tesla Philips Achieva whole-body system, we scanned four times 10 healthy volunteers, in two sessions 2 weeks apart, to obtain QUASAR images. We computed perfusion images and ran a voxel-based analysis within all brain structures. We also calculated mean regional cerebral blood flow (rCBF) within regions of interest configured for each arterial territory distribution.RESULTSThe mean CBF over whole gray matter was 37.74 with intraclass correlation coefficient (ICC) of .70. In white matter, it was 13.94 with an ICC of .30. Voxel-wise ICC and coefficient-of-variation maps showed relatively lower reliability in watershed areas and white matter especially in deeper white matter. The absolute mean rCBF values were consistent with the ones reported from PET, as was the relatively low variability in different feeding arteries.CONCLUSIONSThus, QUASAR reliability for regional perfusion is high within gray matter, but uncertain within white matter.

Alpha and Theta EEG Rhythms Activity Reveal Deep Changes in Resting Brain State in Subjects with Prodromal Alzheimer's Disease

The increase of EEG alpha3/alpha2 frequency power ratio has been associated with AD-converters subjects with mild cognitive impairment (MCI) as well as a reduction in the regional cerebral blood flow (rCBF). In this study, the association between alpha3/alpha2 frequency power ratio with rCBF changes in subjects with MCI was evaluated. The alpha3/alpha2 frequency power ratio was computed in 27 subjects with MCI. Two groups were obtained according to the median values of alpha3/alpha2, at a cut-off of 1.17. In the groups so obtained, the correlation between brain perfusion and EEG markers were detected. In the MCI group with the alpha3/alpha2 frequency power ratio above 1,17 as compared to the group with alpha3/alpha2 frequency power ratio below 1.17 there was: 1) a constant trend to lower rCBF values; 2) smaller hippocampal volumes; 3) higher theta frequency power. The higher EEG alpha3 /alpha2 frequency power ratio individuates two different group of MCI subjects. A complex interplay between alpha and theta rhythms activity MCI patients is suggested in patients with prodromal Alzheimer's disease.

Neural basis of three dimensions of agitated behaviors in patients with Alzheimer disease

BackgroundAgitated behaviors are frequently observed in patients with Alzheimer disease (AD). The neural substrate underlying the agitated behaviors in dementia is unclear. We hypothesized that different dimensions of agitated behaviors are mediated by distinct neural systems.MethodsAll the patients (n=32) underwent single photon emission computed tomography (SPECT). Using the Agitated Behavior in Dementia scale, we identified the relationships between regional cerebral blood flow (rCBF) patterns and the presence of each of three dimensions of agitated behavior (physically agitated behavior, verbally agitated behavior, and psychosis symptoms) in AD patients. Statistical parametric mapping (SPM) software was used to explore these neural correlations.ResultsPhysically agitated behavior was significantly correlated with lower rCBF values in the right superior temporal gyrus (Brodmann 22) and the right inferior frontal gyrus (Brodmann 47). Verbally agitated behavior was significantly associated with lower rCBF values in the left inferior frontal gyrus (Brodmann 46, 44) and the left insula (Brodmann 13). The psychosis symptoms were significantly correlated with lower rCBF values in the right angular gyrus (Brodmann 39) and the right occipital lobe (Brodmann 19).ConclusionOur results support the hypothesis that three different agitated behaviors may represent distinct neural networks in AD patients.

Development of an automatic ROI setting program for input function determination in 99mTc-ECD non-invasive cerebral blood flow quantification

Non-invasive quantitative measurements are useful for clinical study as these are simple and pain-free procedures. A new non-invasive semi-automatic quantitative measurement method, the improved brain uptake ratio (IBUR) method using 99mTc-ECD SPECT, has recently been reported. If an automatic ROI setting algorithm could be developed to determine the input function for the IBUR method, analysis of regional cerebral blood flow (rCBF) can be completed within a few min without recourse to complex techniques, through a fully automatic rCBF analysis program. The purpose of this study was to develop an automatic input function determination program for 99mTc-ECD non-invasive cerebral blood flow quantification and to confirm the feasibility of use of this program.The images of 15 consecutive patients who underwent both 99mTc-ECD chest RI angiography and SPECT examinations were used for development of the automatic arterial input function program. The images of 69 consecutive patients were used for validation of the program.The coincidence ratio between the ROI automatic method and the manual setting method was 98%. The mean difference in the ROI location was ±6.4 mm in the X direction and ±8.6 mm in the Y direction. Individual rCBF values obtained using these independent techniques were also reasonably well correlated (r = 0.95). The total time for the IBUR analysis using the automatic method is 2–3 min as compared to 20–30 min for the current analysis method. This technique improves the throughput of nuclear medical examinations.

Role of CT perfusion imaging in evaluating the effects of multiple burr hole surgery on adult ischemic Moyamoya disease

IntroductionTo evaluate the effects of the multiple burr hole (MBH) revascularization on ischemic type adult Moyamoya disease (MMD) by computed tomography perfusion (CTP).MethodsEighty-six ischemic MMD patients received CTP 1 week before and 3 weeks after MBH operation. Fifty-seven patients received it again at 6 month and underwent digital subtraction angiography (DSA) and mRS follow-up. Cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and relative values of ischemic symptomatic hemispheres were measured. Differences in pre- and post-surgery perfusion CT values were assessed.ResultsThere were significant differences of CBF, TTP, and relative time to peak (rTTP) in ischemic hemisphere between 1 week before and 3 weeks after surgery, and no significant difference in relative cerebral blood flow (rCBF), CBV, relative cerebral blood volume (rCBV), MTT, relative mean transit time (rMTT). According to whether there was symptom improvement or not on 3 weeks after MBH, the rTTP value was not statistically significant in the patients whose symptoms were not improved at all on 3 weeks after operation. Six-month follow-up showed that CBF, rCBF, and rCBV values were significantly higher than those before operation. Postoperative MTT, TTP, rMTT, and rTTP values were significantly lower than those before operation.ConclusionCTP is a sensitive method to obtain functional imaging of cerebral microcirculation, which can be a noninvasive assessment of the abnormalities of intracranial arteries and cerebral perfusion changes in MMD before and after surgery. CBF and TTP map, especially the relative values of TTP, seems to have the capability of being quite sensitive to the presence of altered brain perfusion at early time after indirect revascularization.Electronic supplementary materialThe online version of this article (doi:10.1007/s00234-013-1291-1) contains supplementary material, which is available to authorized users.

Prediction of tissue outcome in acute stroke with perfusion CT

Prediction of tissue outcome in acute stroke with perfusion CT

Cerebral perfusion measured by dynamic susceptibility contrast MRI is reduced in patients with idiopathic normal pressure hydrocephalus

To demonstrate in idiopathic normal pressure hydrocephalus (iNPH) patients by dynamic susceptibility contrast MRI a reduced preoperative cerebral blood flow (CBF) which correlates with the severity of clinical symptoms and predicts shunt outcome. In cortical, subcortical, periventricular regions and along peri-and paraventricular profiles absolute perfusion values were estimated by multi-slice DSC MRI in 21 iNPH patients and 16 age-matched healthy individuals (HI). Relative CBF (rCBF), calculated with the occipital cortex as internal reference, was used for comparison between groups and for correlation analysis between regional rCBF and symptoms or outcome. iNPH patients showed significantly decreased rCBF in the basal medial frontal cortex, hippocampus, lentiform nucleus, periventricular white matter (PVWM), central grey matter and the global parenchyma as compared to HI. iNPH patients with higher preoperative rCBF in the PVWM performed better in clinical tests. A lower overall preoperative function resulted in a more obvious recovery after shunt insertion. Shunt-responders had higher rCBF values in the basal medial frontal cortex than non-responders. DSC MRI perfusion is a potentially useful diagnostic tool in iNPH and perfusion based criteria might be possible predictors of shunt response.

Brain Regions Associated With Cognitive Impairment in Patients With Parkinson Disease

Cognitive impairment is a representative neuropsychiatric presentation that accompanies Parkinson disease (PD). The purpose of this study was to localize the cerebral regions associated with cognitive impairment in patients with PD using quantitative SPECT. Thirty-two patients with PD (mean [SD] age, 75 [8] years; 25 women; Hoehn-Yahr scores from 2 to 5) underwent quantitative brain SPECT using 123I iodoamphetamine. Parametric images of regional cerebral blood flow (rCBF) were spatially normalized to the standard brain atlas. First, voxel-by-voxel comparison between patients with PD with versus without cognitive impairment was performed to visualize overall trend of regional differences. Next, the individual quantitative rCBF values were extracted in representative cortical regions using a standard region-of-interest template to compare the quantitative rCBF values. Patients with cognitive impairment showed trends of lower rCBF in the left frontal and temporal cortices as well as in the bilateral medial frontal and anterior cingulate cortices in the voxel-by-voxel analyses. Region-of-interest-based analysis demonstrated significantly lower rCBF in the bilateral anterior cingulate cortices (right, 25.8 [5.5] vs 28.9 [5.7] mL per 100 g/min, P < 0.05; left, 25.8 [5.8] vs 29.1 [5.7] mL per 100 g/min, P < 0.05) associated with cognitive impairment. Patients with cognitive impairment showed lower rCBF in the left frontal and temporal cortices as well as in the bilateral medial frontal and anterior cingulate cortices. The results suggested dysexecutive function as an underlining mechanism of cognitive impairment in patients with PD.

Cortical control of tongue protrusion and lateral movements in the cat

Based on area P lesion experiments, we hypothesized that tongue protrusion adapted for licking might be regulated by the lateral wall of the presylvian sulcus (bilateral areas P) of the cerebral cortex (Hiraba H, Sato T, Nakakawa K, Ueda K. . Cortical control of appropriate tongue protrusion during licking in cats—Increase in regional cerebral blood flow (rCBF) of the contralateral area P and in tongue protrusion after the unilateral area P lesion. Somatosens Mot Res 26:82–89). We propose that the right and left lingual muscles are dominated by the right and left hypoglossal nucleus, respectively, and that right and left pyramidal cells projecting to the right and left hypoglossal nucleus, respectively, exist in unilateral area P. These cells project via an inhibitory interneuron relay to the lateral branches toward the left or right pyramidal cells in contralateral area P. In this study, we aimed to demonstrate the existence of inhibitory interneurons using injections of a gamma-aminobutyric acid (GABA) agonist (muscimol), a GABA antagonist (bicuculline), and kainic acid into unilateral area P, followed by examination of tongue protrusion and lateral movements during trained licking and changes in regional cerebral blood flow (rCBF) values in the contralateral area P. We found disordered protrusion toward both sides and a marked decrease in rCBF values in the contralateral area P after bicuculline injection. We also found abnormal tongue protrusion toward the front and a marked increase in rCBF values after muscimol and kainic acid injections. These results suggest that cortical networks between the bilateral areas P are relayed by inhibitory interneurons.

Resting-state cerebral blood flow in amygdala is modulated by sex and serotonin transporter genotype

Serotonin transporter-linked polymorphic region (5-HTTLPR) has been associated with modulation of resting-state amygdala level, which was considered to underlie a risk for mood and anxiety disorders. The findings however have been inconsistent which could be related to interactions of the genotype with other factors e.g. sex or personality characteristics. Therefore, the aim of the present study was to explore the modulation of the amygdala perfusion in the resting-state by sex and 5-HTTLPR/rs25531 genotype, controlled for personality dimensions assessed by Temperament and Character Inventory (Cloninger et al., 1994). The resting-state cerebral blood flow (rCBF) was examined using an arterial spin labelling technique. All participants were genotyped for the 5-HTTLPR/rs25531 genotype (L/L-L/S-S/S genotypes and LA-LG variants). The study group comprised 81 right-handed Caucasian healthy volunteers (42 females) aged 19-55 years. We measured rCBF in the amygdala and in the whole-brain grey matter. The data of blood-oxygen-level-dependent (BOLD) response in amygdala to fearful dynamic faces in the same sample were also analysed. There was a significant main effect of sex in both the left and right amygdalae, with higher rCBF in males. Main effect of 5-HTTLPR/rs25531 genotype which was significant in the right amygdala only, was accounted for by higher rCBF in S/S vs. L/L homozygotes. An interaction between sex and 5-HTTLPR/rs25531 genotype was observed in rCBF in the right amygdala. This was accounted for by higher values of rCBF in the right amygdala in males' S allele carriers compared with females. In females, there was a significant negative correlation between the rCBF and BOLD response in the right amygdala, and more so in S carriers. In males, there was no significant correlation between rCBF and BOLD response in the right amygdala. The novelty of our results lies in the demonstration of gene by sex interaction with resting blood flow in the amygdala that elucidates sex-related differences in emotional reactivity.

Perfusion deficits in patients with mild traumatic brain injury characterized by dynamic susceptibility contrast MRI

Perfusion deficits in patients with mild traumatic brain injury (TBI) from a military population were characterized by dynamic susceptibility contrast perfusion imaging. Relative cerebral blood flow (rCBF) was calculated by a model-independent deconvolution approach from the tracer concentration curves following a bolus injection of gadolinium diethylenetriaminepentaacetate (Gd-DTPA) using both manually and automatically selected arterial input functions (AIFs). Linear regression analysis of the mean values of rCBF from selected regions of interest showed a very good agreement between the two approaches, with a regression coefficient of R = 0.88 and a slope of 0.88. The Bland-Altman plot also illustrated the good agreement between the two approaches, with a mean difference of 0.6 ± 12.4 mL/100 g/min. Voxelwise analysis of rCBF maps from both approaches demonstrated multiple clusters of decreased perfusion (p < 0.01) in the cerebellum, cuneus, cingulate and temporal gyrus in the group with mild TBI relative to the controls. MRI perfusion deficits in the cerebellum and anterior cingulate also correlated (p < 0.01) with neurocognitive results, including the mean reaction time in the Automated Neuropsychological Assessment Metrics and commission error and detection T-scores in the Continuous Performance Test, as well as neurobehavioral scores in the Post-traumatic Stress Disorder Checklist-Civilian Version. In conclusion, rCBF calculated using AIFs selected from an automated approach demonstrated a good agreement with the corresponding results using manually selected AIFs. Group analysis of patients with mild TBI from a military population demonstrated scattered perfusion deficits, which showed significant correlations with measures of verbal memory, speed of reaction time and self-report of stress symptoms.

Whole-Brain CT Perfusion and CT Angiography Assessment of Moyamoya Disease before and after Surgical Revascularization: Preliminary Study with 256-Slice CT

Background/AimsThe 256-slice CT enables the entire brain to be scanned in a single examination. We evaluated the application of 256-slice whole-brain CT perfusion (CTP) in determining graft patency as well as investigating cerebral hemodynamic changes in Moyamoya disease before and after surgical revascularization.MethodsThirty-nine cases of Moyamoya disease were evaluated before and after surgical revascularization with 256-slice CT. Whole-brain perfusion images and dynamic 3D CT angiographic images generated from perfusion source data were obtained in all patients. Cerebral blood flow (CBF), cerebral blood volume (CBV), time to peak (TTP) and mean transit time (MTT) of one hemisphere in the region of middle cerebral artery (MCA) distribution and contralateral mirroring areas were measured. Relative CTP values (rCBF, rCBV, rTTP, rMTT) were also obtained. Differences in pre- and post- operation perfusion CT values were assessed with paired t test or matched-pairs signed-ranks test.ResultsPreoperative CBF, MTT and TTP of potential surgical side were significantly different from those of contralateral side (P<0.01 for all). All graft patencies were displayed using the 3D-CTA images. Postoperative CBF, rCBF and rCBV values of surgical side in the region of MCA were significantly higher than those before operation (P<0.01 for all). Postoperative MTT, TTP, rMTT and rTTP values of the surgical side in the region of MCA were significantly lower than those before operation (P<0.05 for all).ConclusionThe 256-slice whole-brain CTP can be used to evaluate cerebral hemodynamic changes in Moyamoya disease before and after surgery and the 3D-CTA is useful for assessing the abnormalities of intracranial arteries and graft patencies.

Anteroposterior perfusion heterogeneity in human hippocampus measured by arterial spin labeling MRI

Measurements of blood flow in the human hippocampus are complicated by its relatively small size, unusual anatomy and patterns of blood supply. Only a handful of arterial spin labeling (ASL) MRI articles have reported regional cerebral blood flow (rCBF) values for the human hippocampus. Numerous reports have found heterogeneity in a number of other physiological and biochemical parameters along the longitudinal hippocampal axis. There is, however, only one ASL study of perfusion properties as a function of anteroposterior location in the hippocampus, reporting that rCBF is lower and the arterial transit time (ATT) is longer in the anterior hippocampus than in the posterior hippocampus of the rat brain. The purpose of this article was to measure ATT and rCBF in anterior, middle and posterior normal adult human hippocampus. To better distinguish anteroposterior perfusion heterogeneity in the hippocampus, a modified ASL method, called Orthogonally Positioned Tagging Imaging Method for Arterial Labeling with Flow-sensitive Alternating Inversion Recovery (OPTIMAL FAIR), was developed that provides high in-plane resolution with oblique coronal imaging slices perpendicular to the long axis of the hippocampus to minimize partial volume effects. Perfusion studies performed with this modified FAIR method at 3 T indicated that anterior, middle and posterior human hippocampus segments have unique transit time and rCBF values. Of these three longitudinal hippocampal regions, the middle hippocampus has the highest perfusion and the shortest transit time and the anterior hippocampus has the lowest perfusion and the longest transit time. Copyright © 2013 John Wiley & Sons, Ltd.

Periprocedural Arterial Spin Labeling and Dynamic Susceptibility Contrast Perfusion in Detection of Cerebral Blood Flow in Patients With Acute Ischemic Syndrome

To compare the diagnostic performance of arterial spin-labeling (ASL) and dynamic susceptibility contrast (DSC) perfusion in detecting cerebral blood flow (CBF) changes before and after endovascular recanalization in acute ischemic syndrome. The inclusion criteria for this retrospective study were patients with acute ischemic syndrome who underwent endovascular recanalization and acquisition of both ASL and DSC before and after revascularization. ASL-CBF and multiparametric DSC maps were evaluated for image quality, location, and type of perfusion abnormality. Relative CBF (rCBF) was calculated in the infarction core and hypoperfused areas using coregistered ASL and DSC. Core and hypoperfused rCBF were used for paired pretreatment and posttreatment comparisons. Interobserver and intermodality agreement were evaluated by κ test, and t test was calculated for ASL and DSC rCBF values. Twenty-five patients met our inclusion criteria. Five studies were rated nondiagnostic, resulting in 45 pairs of DSC-ASL available for comparison. ASL and DSC agreed on type and location of the perfusion abnormality in 71% and 80% of cases, respectively. The image quality of ASL was lower than DSC, resulting in interobserver variability for the type (κ=0.45) and location (κ=0.56) of perfusion abnormality. ASL was unable to show any type of perfusion abnormality in 11% of patients. In successfully recanalized patients, hyperperfusion (rCBF >1) was detected in 100% on DSC and 47% on ASL. ASL is less sensitive than DSC for detecting rCBF changes in patients with acute ischemic syndrome, particularly with respect to hyperperfusion after successful recanalization.