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Background: The association of Mini-Mental State Examination (MMSE) with microstructure of individual regions across the entire brain remains unexplored., Purpose: To investigate the relationship between cognitive function and the microstructure of each brain region in the gray matter using diffusion kurtosis imaging (DKI) in older adults with mild cognitive impairment (MCI), which is the transitional stage before the onset of dementia., Material and Methods: DKI and MMSE were obtained for 34 older adults with MCI and 16 cognitively normal (CN) individuals aged 65-85 years. The DKI parameters were measured from 31 distinct regions of interest in the gray matter. A multiple regression analysis was used to examine the association between DKI parameters and MMSE scores; subsequently, interactions between the DKI parameters and the groups (MCI and CN) were examined., Results: The mean (±SD) MMSE score for the MCI group was 27.67 ± 1.90. Significant positive correlations were observed between MMSE score and mean kurtosis (MK) in the superior frontal, middle frontal, inferior frontal, precentral, postcentral, angular, middle temporal, and inferior occipital gyri, and superior parietal lobe for the MCI group. In addition, the interaction term of the MK in the middle frontal, precentral, postcentral, and angular gyri, and the groups was statistically significant., Conclusion: Older adults with MCI may exhibit histological damage in certain regions of the brain, such as the middle frontal and angular gyri, as observed in this study. The findings could provide insights into understanding the pathophysiology of cognitive decline in this population group., Competing Interests: Declaration of conflicting interestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

We investigated the spatial and temporal variations of flip-angle (FA) distributions in the human brain from multiple scans, using an eight-channel parallel transmission (pTx) system at 7T. Nine healthy volunteers were scanned in five sessions using three radiofrequency excitation techniques each time: circular polarization (CP), static pTx, and dynamic pTx. We calculated the coefficients of variation of the FA values within the brain area to evaluate the variations, and the maximum intersession differences in the FA values (D max ), comparing them between the three methods. The coefficients of variation decreased in the following order: CP, static pTx, and dynamic pTx (median: 20.1%, 13.6%, and 5.7%, respectively; p < 0.001). The average D max values were significantly higher for the static pTx (5.4°) than for the dynamic pTx (2.8°) and CP (1.7°) methods (p = 0.004 and 0.001, respectively). Compared to the CP method, the dynamic pTx method at 7T can efficiently minimize spatial variations in the FA distribution with a mild increase in temporal variations. The static pTx method exhibited a remarkably wide temporal variation.

Purpose: The feasibility of steady-state sequences for 17 O imaging was evaluated based on a kinetic analysis of the brain parenchyma and cerebrospinal fluid (CSF)., Materials and Methods: The institutional review board approved this prospective study with written informed consent. Dynamic 2D or 3D steady-state sequences were performed in five and nine participants, respectively, with different parameters using a 3T scanner. During two consecutive dynamic scans, saline was intravenously administered for control purposes in the first scan, and 20% 17 O-labeled water (1 mL/Kg) was administered in the second scan. Signal changes relative to the baseline were calculated, and kinetic analyses of the curves were conducted for all voxels. Region of interest analysis was performed in the brain parenchyma, choroid plexus, and CSF spaces., Results: Average signal drops were significantly larger in the 17 O group than in the controls for most of the imaging parameters. Different kinetic parameters were observed between the brain parenchyma and CSF spaces. Average and maximum signal drops were significantly larger in the CSF spaces and choroid plexus than in the brain parenchyma. Bolus arrival, time to peak, and the first moment of dynamic curves of 17 O in the CSF space were delayed compared to that in the brain parenchyma. Significant differences between the ventricle and subarachnoid space were also noted., Conclusion: Steady-state sequences are feasible for indirect 17 O imaging with reasonable temporal resolution; this result is potentially important for the analysis of water kinetics and aquaporin function for several disorders.

Background: Respiration-induced phase shift affects B 0 /B 1 mapping repeatability in parallel transmission (pTx) calibration for 7T brain MRI, but is improved by breath-holding (BH). However, BH cannot be applied during long scans.+ mapping repeatability in parallel transmission (pTx) calibration for 7T brain MRI, but is improved by breath-holding (BH). However, BH cannot be applied during long scans., Purpose: To examine whether interleaved acquisition during calibration scanning could improve pTx repeatability and image homogeneity., Study Type: Prospective., Subjects: Nine healthy subjects., Field Strength/sequence: 7T MRI with a two-channel RF transmission system was used., Assessment: Calibration scanning for B 0 /B 1 + mapping was performed under sequential acquisition/free-breathing (Seq-FB), Seq-BH, and interleaved acquisition/FB (Int-FB) conditions. The B 0 map was calculated with two echo times, and the B 1 + map was obtained using the Bloch-Siegert method. Actual flip-angle imaging (AFI) and gradient echo (GRE) imaging were performed using pTx and quadrature-Tx (qTx). All scans were acquired in five sessions. Repeatability was evaluated using intersession standard deviation (SD) or coefficient of variance (CV), and in-plane homogeneity was evaluated using in-plane CV., Statistical Tests: A paired t-test with Bonferroni correction for multiple comparisons was used., Results: The intersession CV/SDs for the B 0 /B 1 + maps were significantly smaller in Int-FB than in Seq-FB (Bonferroni-corrected P < 0.05 for all). The intersession CVs for the AFI and GRE images were also significantly smaller in Int-FB, Seq-BH, and qTx than in Seq-FB (Bonferroni-corrected P < 0.05 for all). The in-plane CVs for the AFI and GRE images in Seq-FB, Int-FB, and Seq-BH were significantly smaller than in qTx (Bonferroni-corrected P < 0.01 for all)., Data Conclusion: Using interleaved acquisition during calibration scans of pTx for 7T brain MRI improved the repeatability of B 0 /B 1 + mapping, AFI, and GRE images, without BH., Level of Evidence: 1 Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2017., (© 2017 International Society for Magnetic Resonance in Medicine.)

Gambierol and its two, tetra- and heptacyclic, analogues have been previously proved as promising molecules for the modulation of Alzheimer's disease (AD) hallmarks in primary cortical neurons of 3xTg-AD fetuses. In this work, the effect of the tetracyclic analogue of gambierol was tested in vivo in 3xTg-AD mice (10 months old) after 1 month of weekly treatment with 50 μg/kg. Adverse effects were not reported throughout the whole treatment period and no pathological signs were observed for the analyzed organs. The compound was found in brain samples after intraperitoneal injection. The tetracyclic analogue of gambierol elicited a decrease of amyloid β 1-42 levels and a dose-dependent inhibition of β-secretase enzyme-1 activity. Moreover, this compound also reduced the phosphorylation of tau at the 181 and 159/163 residues with an increase of the inactive isoform of the glycogen synthase kinase-3β. In accordance with our in vitro neuronal model, this compound produced a reduction in the N2A subunit of the N-methyl-d-aspartate (NMDA) receptor. The combined effect of this compound on amyloid β 1-42 and tau phosphorylation represents a multitarget therapeutic approach for AD which might be more effective for this multifactorial and complex neurodegenerative disease than the current treatments.

Objective: Preterm infants are at high risk for developmental delay, epilepsy, and autism spectrum disorders. Some reports have described associations between these conditions and gamma-aminobutyric acid (GABA) dysfunction; however, no study has evaluated temporal changes in GABA in preterm infants. Therefore, we assessed temporal changes in brain metabolites including GABA using single-voxel 3-Tesla (T) proton magnetic resonance spectroscopy ( 1 H-MRS) in preterm infants with normal development., Methods: We performed 3T 1 H-MRS at 37-46 postmenstrual weeks (PMWs, period A) and 64-73PMWs (period B). GABA was assessed with the MEGA-PRESS method. N-acetyl aspartate (NAA), glutamate-glutamine complex (Glx), creatine (Cr), choline (Cho), and myo-inositol (Ins) were assessed with the PRESS method. Metabolite concentrations were automatically calculated using LCModel., Results: Data were collected from 20 preterm infants for periods A and B (medians [ranges], 30 [24-34] gestational weeks, 1281 [486-2030]g birth weight). GABA/Cr ratio decreased significantly in period B (p=0.03), but there was no significant difference in GABA/Cho ratios (p=0.58) between the two periods. In period B, NAA/Cr, Glx/Cr, NAA/Cho, and Glx/Cho ratios were significantly increased (p<0.01), whereas Cho/Cr, Ins/Cr, and Ins/Cho ratios were significantly decreased (p<0.01). There was no significant difference for GABA or Cho concentrations (p=0.52, p=0.22, respectively). NAA, Glx, and Cr concentrations were significantly increased (p<0.01), whereas Ins was significantly decreased (p<0.01)., Conclusions: Our results provide new information on normative values of brain metabolites in preterm infants., (Copyright © 2016 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.)

Purpose: The B0 and B1+ maps required for calculation of the radiofrequency (RF) pulse of parallel transmission (pTx) are obtained in calibration scans; however, they may be affected by respiratory motion. We aimed to compare the reproducibility of B0 and B1+ maps and gradient echo (GRE) images of the brain scanned with pTx at 7T between free-breathing (FB) and breath-holding (BH) conditions during the calibration scan., Methods: Nine healthy volunteers were scanned by 7T MRI using a two-channel quadrature head coil. In the pTx calibration scans performed with FB and BH, the B0 map was obtained from two different TE images and the B1+ map was calculated by the Bloch-Siegert method. A GRE image (gradient-recalled-acquisition in steady state) was also obtained with RF shimming and RF design of pTx with spoke method, as well as quadrature transmission (qTx). All the scans were repeated over five sessions. The reproducibility of the B0 and B1+ maps and GRE image was evaluated with region-of-interest measurements using inter-session standard deviation (SD) and coefficient of variation (CV) values. Intensity homogeneity of GRE images was also assessed with in-plane CV., Results: Inter-session SDs of B0 and B1+ maps were significantly smaller in BH (P < 0.01). Inter-session CVs of GRE images were significantly smaller in qTx than BH and FB (P < 0.01, both); however, the CVs of BH were significantly smaller (P < 0.01). In-plane CVs of FB and BH with RF shimming were not significantly different with qTx; however, CVs of FB and BH with RF design were significantly smaller than those of qTx (P < 0.05 and P < 0.01, respectively)., Conclusion: BH could improve the reproducibility of B0 and B1+ maps in pTx calibration scans and GRE images. These results might facilitate the development of pTx in human brain at 7T.

Conscious sedation with propofol sometimes causes amnesia while keeping the patient awake. However, it remains unknown how propofol compromises the memory function. Therefore, we investigated the changes in brain activation induced by visual stimulation during and after conscious sedation with propofol using serial functional MRI. Healthy volunteers received a target-controlled infusion of propofol, and underwent functional MRI scans with a block-design paradigm of visual stimulus before, during, and after conscious sedation. Random-effect model analyses were performed using Statistical Parametric Mapping software. Among the areas showing significant activation in response to the visual stimulus, the visual cortex and fusiform gyrus were significantly suppressed in the sedation session and tended to recover in the early-recovery session of ∼20 min (P<0.001, uncorrected). In contrast, decreased activations of the hippocampus, thalamus, inferior frontal cortex (ventrolateral prefrontal cortex), and cerebellum were maintained during the sedation and early-recovery sessions (P<0.001, uncorrected) and were recovered in the late-recovery session of ∼40 min. Temporal changes in the signals from these areas varied in a manner comparable to that described by the random-effect model analysis (P<0.05, corrected). In conclusion, conscious sedation with propofol may cause prolonged suppression of the activation of memory-related structures, such as the hippocampus, during the early-recovery period, which may lead to transient amnesia.

The purposes of this study are to establish oxygen extraction fraction (OEF) measurements using quantitative susceptibility mapping (QSM) of magnetic resonance imaging (MRI), and to compare QSM-OEF data with the gold standard (15)O positron emission tomography (PET). Twenty-six patients with chronic unilateral internal carotid artery or middle cerebral artery stenosis or occlusion, and 15 normal subjects were included. MRI scans were conducted using a 3.0 Tesla scanner with a three-dimensional spoiled gradient recalled sequence. QSM images were created using the morphology-enabled dipole inversion method, and OEF maps were generated from QSM images using extraction of venous susceptibility induced by deoxygenated hemoglobin. Significant correlation of relative OEF ratio to contra-lateral hemisphere between QSM-OEF and PET-OEF was observed (r = 0.62, p < 0.001). The local (intra-section) correlation was also significant (r = 0.52, p < 0.001) in patients with increased PET-OEF. The sensitivity and specificity of OEF increase in QSM was 0.63 (5/8) and 0.89 (16/18), respectively, in comparison with PET. In conclusion, good correlation was achieved between QSM-OEF and PET-OEF in the identification of elevated OEF in affected hemispheres of patients with unilateral chronic steno-occlusive disease., (© The Author(s) 2015.)

Purpose: To investigate temporal changes in brain metabolites during the first year of life in preterm infants using multivoxel proton magnetic resonance spectroscopy ((1)H-MRS)., Methods: Seventeen infants born at 29 (25-33) gestational week (median, range) weighing 1104 (628-1836) g underwent 1.5-T multivoxel (1)H-MRS at 42 postconceptional week (PCW) and at 3, 6, 9, and 12 months after. We measured N-acetyl aspartate (NAA)/creatine (Cr), choline (Cho)/Cr, myo-inositol (Ins)/Cr, NAA/Cho, and Ins/Cho ratios in the frontal lobe (FL) and basal ganglia and thalamus (BG + Th). Linear regression analyses were performed to identify longitudinal changes in infants showing normal imaging findings and normal development. We also evaluated ratios of subjects with abnormal imaging findings and/or development using the 95% confidence intervals (CIs) of regression equations in normal subjects., Results: In the 13 infants with normal development, NAA/Cr and NAA/Cho ratios showed significant positive correlations with PCWs in the FL (r = 0.64 and 0.83, respectively, both P < 0.01) and BG + Th (r = 0.79 and 0.87, respectively, both P < 0.01), while Cho/Cr and Ins/Cr ratios revealed significant negative correlations with PCWs in the FL (r =-0.69 and -0.58, respectively, both P < 0.01) and BG + Th (r =-0.74 and -0.72, respectively, both P < 0.01). Ins/Cho ratios in the FL did not significantly correlate with PCWs (r =-0.19, P = 0.18), while those in the BG + Th showed significant negative correlation with PCWs (r =-0.44, P < 0.01). The metrics in the abnormal group were within the normal group 95% CIs in all periods except a few exceptions., Conclusions: Longitudinal multivoxel MRS is able to detect temporal changes in major brain metabolites during the first year of life in preterm infants.

Background & Purpose: In this work, we demonstrate oxygen extraction fraction (OEF) measurement using 7T MRI with susceptibility-weighted imaging (SWI), in sedated and nonsedated adults., Methods: Ten healthy subjects (30.3 ± 4.5 years, 9 men, 1 woman) formed control (n = 5) and sedation groups (n = 5). Midazolam and propofol injection was administered to the same sedation group subjects during 2 different scanning sessions. Two-dimensional SPGR imaging was performed before, during, and twice after (propofol, +10, +30 minutes; midazolam, +10, +40 minutes) conscious sedation. The equivalent procedure was performed with the control group without sedation. After SWI analysis, change in OEF between scans was quantified, and parcelated ΔOEF maps were generated with 77 gray matter (GM)-containing volumes-of-interest (VOIs)., Results: Significant decreases in OEF were shown in 14 GM VOIs during sedation relative to the control group, most notably during midazolam sedation (P < .05). In contrast, no significant decrease was observed after 10 minutes and in only 4 VOIs after 40 minutes recovery., Conclusion: Significant change in ΔOEF during conscious sedation using midazolam and propofol could be measured using SWI at 7T in vivo. This may be a potentially useful approach for the noninvasive assessment of OEF in the brain on a clinical basis., (Copyright © 2014 by the American Society of Neuroimaging.)

Differential diagnoses among Parkinson's disease (PD), multiple system atrophy (MSA), and progressive supranuclear palsy syndrome (PSPS) are often difficult. Hence, we investigated whether diffusion kurtosis imaging (DKI) could detect pathological changes that occur in these disorders and be used to differentiate between such patients. Fourteen patients (five with PD, four MSA, and five PSPS) and six healthy controls were examined using a 1.5-T scanner. Mean kurtosis (MK), fractional anisotropy, and mean diffusivity maps were generated, and these values of the midbrain tegmentum (MBT) and pontine crossing tract (PCT), as well as MBT/PCT ratios, were obtained. We found no significant differences in MBT and PCT values on DKI maps among the groups. In contrast, MBT/PCT ratios from MK maps were significantly increased in the MSA group and decreased in the PSPS group compared with the other groups. MBT/PCT ratios from mean diffusivity maps showed a significant increase in the PSPS group. Therefore, quantitative DKI analyses, particularly the MBT/PCT ratio from MK maps, can differentiate patients with parkinsonisms., (Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.)

Neuropsychiatric systemic lupus erythematosus (NPSLE) is speculated to be caused by disturbed microcirculation of the central nervous system. However, characteristic imaging findings of NPSLE have not been established. Hence, we investigated whether high-resolution images obtained using ultrahigh field MRI at 7 T can detect microcerebrovascular lesions in patients with NPSLE that have never been detected by conventional MRI. We prospectively examined 20 patients with SLE, including five with NPSLE, using a 7 T MRI scanner. High-resolution two-dimensional T2-weighted images and high-resolution three-dimensional T1-weighted images (T1WIs) before and after the administration of contrast agents were obtained. On the high-resolution T1WIs obtained at 7 T, minute punctate/linear hyperintense lesions in subcortical and/or cortical areas were found in four (80%) NPSLE patients and one (7%) non-NPSLE patient. Further, the minute punctate enhanced lesions in these areas were found on contrast-enhanced T1WIs in only three (60%) NPSLE patients. These findings suggesting microvascular thrombi or inflammation were significantly more frequent in NPSLE than in non-NPSLE patients (P=0.001). In contrast, other imaging findings, laboratory findings, and clinical characteristics were not different between the two groups. High-resolution T1WIs obtained at 7 T can detect minute lesions, indicating intracerebral microvascular lesions in patients with NPSLE.

Purpose: To evaluate the performance and efficacy for intensity inhomogeneity correction of various sequences of the human brain in 7T MRI using the extended version of the unified segmentation algorithm., Materials: Ten healthy volunteers were scanned with four different sequences (2D spin echo [SE], 3D fast SE, 2D fast spoiled gradient echo, and 3D time-of-flight) by using a 7T MRI system. Intensity inhomogeneity correction was performed using the "New Segment" module in SPM8 with four different values (120, 90, 60, and 30 mm) of full width at half maximum (FWHM) in Gaussian smoothness. The uniformity in signals in the entire white matter was evaluated using the coefficient of variation (CV); mean signal intensities between the subcortical and deep white matter were compared, and contrast between subcortical white matter and gray matter was measured. The length of the lenticulostriate (LSA) was measured on maximum intensity projection (MIP) images in the original and corrected images., Results: In all sequences, the CV decreased as the FWHM value decreased. The differences of mean signal intensities between subcortical and deep white matter also decreased with smaller FWHM values. The contrast between white and gray matter was maintained at all FWHM values. LSA length was significantly greater in corrected MIP than in the original MIP images., Conclusions: Intensity inhomogeneity in 7T MRI can be successfully corrected using SPM8 for various scan sequences.

Rationale and Objectives: The effects of low thyroid hormone level during embryogenesis on MRI of the brain and social behaviors of hatchlings were examined using "fertilized hen's egg-embryo-chick" system., Methods and Results: Control and hatchlings treated with methimazole (20 μmol/egg), which hatched 3 days later than controls were examined. The results are as follows: 1. The MRI examination of the midsagittal section of the brain on hatch day showed that the sizes, by T1- and ADC values by diffusion-weighted images, of the optic lobe and cerebellum of the MMI-hatchlings were significantly bigger than those of the controls. 2. The social behaviors on post-hatch day 3 were based on the following tests: (a) Aggregation test: The speed of four chicks, individually isolated by cardboard barriers in a box, to make a group upon the removal of barriers. (b) Belongingness tests: The speed of a chick isolated at a corner to join the group of three chicks placed at the opposite corner. (c) Vocalization test: The number of decibel produced by a chick isolated at a corner using a sound meter. These tests demonstrated that MMI-hatchlings took longer times and had weaker vocalization than the controls, significantly. 3. Upregulation of THRβ mRNA after MMI treatment suggested that THR was necessary for cerebellum development., Conclusions: The MMI exposure during the last week of embryogenesis possibly delayed the myelination of certain brain regions and impaired the social behaviors of hatchlings. The chick embryos can be easily induced with hypothyroidism without maternal influences, and the hatchling's behaviors were analyzed using a video camera. The present method will be useful for assessing the effects of unfavorable influences during embryogenesis on social behaviors in later life.

Background: Carotid endarterectomy (CEA) might improve cognitive function. Fractional anisotropy (FA) values in the cerebral white matter derived from diffusion tensor magnetic resonance imaging (DTI) correlate with cognitive function in patients with various central nervous system diseases., Objective: To use tract-based spatial statistics to determine whether postoperative changes of FA values in the cerebral white matter derived from DTI are associated with cognitive improvement after uncomplicated CEA., Methods: In 80 patients undergoing CEA for ipsilateral internal carotid artery stenosis (≥70%), FA values in the cerebral white matter were derived from DTI before and 1 month after surgery and were analyzed by using tract-based spatial statistics. Neuropsychological testing, consisting of the Wechsler Adult Intelligence Scale Revised, the Wechsler Memory Scale and the Rey-Osterreith Complex Figure test, was also performed preoperatively and after the first postoperative month., Results: Based on the neuropsychological assessments, 11 (14%) patients were defined as having postoperatively improved cognition. The difference between the 2 mean FA values (postoperative values minus preoperative values) in the cerebral hemisphere ipsilateral to surgery was significantly associated with postoperative cognitive improvement (95% confidence intervals, 2.632-9.877; P = .008). White matter FA values in patients with postoperative cognitive improvement were significantly increased after surgery in the whole ipsilateral cerebral hemisphere, in the contralateral anterior cerebral artery territory, and in the watershed zone between the contralateral anterior and middle cerebral arteries., Conclusion: Postoperative increase in cerebral white matter FA on DTI is associated with cognitive improvement after uncomplicated CEA.

Purpose: To develop a map to detect changes in oxygen extraction fraction (OEF) utilizing susceptibility-weighted (SW) phase images and to correlate such changes in OEF with those in cerebral blood flow (CBF)., Materials and Methods: The study protocol was approved by the institutional review board, and written informed consent was obtained from all subjects. Eight healthy volunteers (mean age ± standard deviation, 29.8 years ± 4.6) were included in the study. Subjects were evaluated by using SW imaging, and the change in OEF was calculated by subtracting the image at baseline from one of the images obtained during six different conditions, including two at resting state, three different types of respiratory challenges, and one drug challenge with acetazolamide. Arterial spin labeling was carried out to measure CBF, while SW imaging was used to generate maps of change in OEF in response to a given condition. Statistical tests included one-way analysis of variance and Dunnett multiple comparisons to compare among the six conditions the magnitude of change from baseline for both OEF and CBF, by using the OEF change at resting state (resting 1) as the control., Results: Hyperventilation caused a statistically significant decrease in CBF (-29.3%, P < .001) and an increase in OEF (+5.2%, P < .001) compared with the control, resting 1 (+2.2%, -0.7%, respectively). Acetazolamide caused a significant increase in CBF (+39.7%, P < .001) and a decrease in OEF (-3.4%, P = .040). Carbogen also induced a CBF increase (+16.2%); however, the change was not significant (P = .090), even though OEF decreased significantly (-4.2%, P = .003). Oxygen administration resulted in a significant CBF decrease (-27.2%, P < .001), whereas OEF showed no significant difference (-0.6%, P > .99)., Conclusion: Maps of changes in OEF generated from SW phase images revealed changes in OEF corresponding to anticipated changes in CBF induced by various conditions; SW phase imaging might, in the future, be applied to evaluate cerebrovascular and other cerebral disorders in which changes in oxygen metabolism are important for planning therapeutic strategies., (© RSNA, 2011.)

Objective: The authors examined whether (1)H-magnetic resonance spectroscopy (MRS) can identify damage to the centrum semiovale in the subacute phase after CO exposure., Methods: Subjects comprised 29 adult patients who were treated with hyperbaric oxygenation within a range of 4-95 h (mean 18.7 h) after CO exposure. Subjects were classified into three groups according to clinical behaviours: Group A, patients with transit acute symptoms only; Group P, patients with persistent neurological symptoms; and Group D, patients with 'delayed neuropsychiatric sequelae' occurring after a lucid interval. MRS of bilateral centrum semiovale was performed 2 weeks after CO inhalation for all patients and 13 healthy volunteers. The mean ratios of choline-containing compounds/creatine ((mean)Cho/Cr) and N-acetylaspartate/Cr ((mean)NAA/Cr) for bilateral centrum semiovale were calculated and compared between the three CO groups and controls. Myelin basic protein (MBP) concentration in cerebrospinal fluid was examined at 2 weeks to evaluate the degree of demyelination in patients., Results: MBP concentration was abnormal for almost all patients in Groups P and D, but was not abnormal for any Group A patients. The (mean)Cho/Cr ratios were significantly higher in Groups P and D than in Group A. No significant difference in (mean)NAA/Cr ratio was seen between the three pathological groups and controls. A significant correlation was identified between MBP and (mean)Cho/Cr ratio., Conclusions: These results suggest that the Cho/Cr ratio in the subacute phase after CO intoxication represents early demyelination in the centrum semiovale, and can predict chronic neurological symptoms.

The time-to-maximum of the tissue residue function (T(max)) perfusion index has proven very predictive of infarct growth in large clinical trials, yet its dependency on simple tracer delays remains unknown. Here, we determine the dependency of computed tomography (CT) perfusion (CTP) T(max) estimates on tracer delay using a range of deconvolution techniques and digital phantoms. Digital phantom data sets simulating the tracer delay were created from CTP data of six healthy individuals, in which time frames of the left cerebral hemisphere were shifted forward and backward by up to ±5 seconds. These phantoms were postprocessed with three common singular value decomposition (SVD) deconvolution algorithms-standard SVD (sSVD), block-circulant SVD (bSVD), and delay-corrected SVD (dSVD)-with an arterial input function (AIF) obtained from the right middle cerebral artery (MCA). The T(max) values of the left hemisphere were compared among different tracer delays and algorithms by a region of interest-based analysis. The T(max) values by sSVD were positively correlated with 'positive shifts' but unchanged with 'negative shifts,' those by bSVD had an excellent positive linear correlation with both positive and negative shifts, and those by dSVD were relatively constant, although slightly increased with the positive shifts. The T(max) is a parameter highly dependent on tracer delays and deconvolution algorithm.

Introduction: We attempted to detect alterations in the cerebrospinal fluid (CSF) space in patients with idiopathic normal pressure hydrocephalus (iNPH) using voxel-based morphometry (VBM)., Methods: We obtained sagittal volume images of the entire head by three-dimensional T1-weighted magnetic resonance imaging and compared the regional distribution of CSF in 12 patients with iNPH, 14 patients with Alzheimer's disease (AD), and 17 healthy individuals using VBM with automatically extracted CSF objects., Results: VBM demonstrated significant widening at the lateral ventricles and Sylvian fissures and narrowing of the CSF space at the high convexity/midline areas in iNPH patients, compared to the AD patients and healthy controls (p < 0.05, after correction with a false-discovery rate). In addition, the ratio of the CSF volume in the lateral ventricle/Sylvian fissure area to that in the high convexity/midline area in iNPH patients (3.9 +/- 1.2) was remarkably greater than that in AD patients (1.2 +/- 0.3) and controls (0.9 +/- 0.3; one-way ANOVA, p < 0.001; post hoc Tukey's test, p < 0.001); we could discriminate iNPH patients from those in the other two groups without any overlap, when using a cutoff level of 1.9., Conclusion: VBM using CSF objects can be used to delineate the characteristic alteration of the CSF space in iNPH patients, which has been evaluated by visual interpretation.

Proton magnetic resonance spectroscopy, diffusion-weighted axonography, and diffusion tensor tractography in a patient with tumefactive demyelination plaque (TDP) were evaluated for differential diagnosis from glioblastoma. The findings of glutamate and glutamine elevations on magnetic resonance spectroscopy and apparent tracts within the lesion on axonography and tractography were unlikely to represent glioblastoma, and were thus useful for the preoperative diagnosis of TDP.

Institutional review board approval and informed consent were obtained. The purpose was to evaluate the differences in tracer delay-induced effects of various deconvolution algorithms for computed tomographic (CT) perfusion imaging by using digital phantoms created from actual source data. Three methods of singular value decomposition (SVD) were evaluated. For standard SVD (sSVD), the delays induced significant errors in cerebral blood flow and mean transit time. In contrast, for block-circulant SVD (bSVD), these values remained virtually unchanged, whereas for delay-corrected SVD (dSVD), mild changes were observed. bSVD was superior to sSVD and dSVD for avoiding the tracer delay-induced effects in CT perfusion imaging.

Purpose: The aim of the present study was to determine whether preoperative cerebrovascular reactivity (CVR) to acetazolamide measured by quantitative brain perfusion single-photon emission computed tomography (SPECT) predicts development of cerebral ischemic lesions on postoperative diffusion-weighted magnetic resonance imaging (DWI) that are caused by microemboli during carotid endarterectomy (CEA)., Materials and Methods: One hundred and fifty patients with ipsilateral internal carotid artery stenosis (>70%) underwent CEA under transcranial Doppler monitoring of microembolic signals (MES) in the ipsilateral middle cerebral artery (MCA). Preoperative CVR to acetazolamide was measured using [(123)I]N-isopropyl-p-iodoamphetamine SPECT, and region of interest (ROI) analysis in the ipsilateral MCA territory was performed using a three-dimensional stereotaxic ROI template. DWI was performed within 3 days before and 24 h after surgery., Results: Twenty-six patients (17.3%) developed new postoperative ischemic lesions on DWI. Logistic regression analysis demonstrated that, among the variables tested, a high number of MES during carotid dissection (95% CIs, 1.179 to 1.486; P < 0.0001) and preoperative reduced CVR to acetazolamide (95% CIs, 0.902 to 0.974; P = 0.0008), which were significantly associated with the development of new postoperative ischemic lesions on DWI. In 47 patients with MES during carotid dissection, the combination of number of MES during carotid dissection and CVR to acetazolamide identified development of new postoperative ischemic lesions on DWI with a positive predictive value of 100% or zero., Conclusions: Preoperative CVR to acetazolamide measured by quantitative brain perfusion SPECT predicts development of cerebral ischemic lesions on postoperative DWI that are caused by microemboli during CEA.

The advents of multidetector-row CT and high-field MRI have accelerated the technical advancement of the stroke CT and MRI. A novel technique combining volume helical scan and three-dimensional denoising filter can improve conspicuity of the early CT signs by increasing the signal-to-noise ratio and reducing bone-related artifacts. High-filed MRI allows us to use new techniques, such as the susceptibility-weighted imaging, myelin-density imaging, volume diffusion imaging, and neuromelanin imaging. Standardization techniques for the stroke CT and MRI introduced by ASIST-Japan can reduce inter-institutional and intervendor differences, and helps in facilitating multicenter trials concerning acute stroke management.

Purpose: We used a whole-brain, isotropic-voxel acquisition technique to improve the geometric distortion in diffusion-weighted (DWI) and diffusion tensor imaging (DTI) in coronal directions, which is remarkable at high magnetic fields., Materials and Methods: We performed magnetic resonance imaging of 17 healthy volunteers using a 3T scanner and obtained coronal DWI/DTI as well as coronal images that were reformatted from isotropic volume data acquired by 1.6-mm-thick axial DWI/DTI. We visually evaluated the degree of image distortion and quantitated the findings by co-registration analysis., Results: In-plane geometric distortions in coronal DWI/DTI, particularly at the frontal base and medial temporal lobe, were dramatically diminished when the isotropic-voxel acquisition technique was used. Quantitative measurement revealed a reduction in areas of misregistration, but not their absence, in reformatted coronal images, mainly because of distortion in the anteroposterior direction in the source images., Conclusion: The isotropic-voxel DWI/DTI technique enabled acquisition of coronal images that represented anatomical details accurately with permissible spatial distortion while maintaining spatial resolution, even at 3T.

A 67-year-old woman with a recent history of recurrent ischemic stroke secondary to right vertebral artery stenosis suffered acute onset of left homonymous hemianopsia and the medial longitudinal fasciculus syndrome, which resolved with hyperdynamic therapy. However, consciousness deteriorated 6 hours later. Perfusion computed tomography (CT) revealed regions of prolonged mean transit time in the bilateral cerebellar hemispheres, vermis, brainstem, and right occipital lobe, which were more extensive than the ischemic lesions demonstrated by diffusion-weighted magnetic resonance (MR) imaging. Subsequent cerebral angiography showed occlusion of the right vertebral artery. The patient underwent emergent left superficial temporal artery to left superior cerebellar artery bypass. Postoperatively she demonstrated resolution of the preoperative perfusion CT/diffusion-weighted MR imaging mismatch and improved neurological deficits. Early revascularization in a patient with perfusion CT/diffusion-weighted MR imaging mismatch following acute vertebrobasilar stroke can lead to improvement in cerebral perfusion and neurological function.

Accumulating evidence suggests that central thyrotropin-releasing hormone (TRH) administration induces gastric erosion 4 h after administration through the vagal nerves. However, early changes in the gastric mucosa during these 4 h have not been described. To assess early changes in the gastric mucosa after intracisternal injection of a stable TRH analog, pGlu-His-(3,3'-dimethyl)-ProNH2 (RX-77368), we measured the blood-to-lumen 51Cr-labeled EDTA clearance and examined the effects of vagotomy, atropine, omeprazole, and hydrochloric acid (HCl) on RX-77368-induced mucosal permeability. A cytoprotective dose of RX-77368 (1.5 ng) did not increase mucosal permeability. However, higher doses significantly increased mucosal permeability. Permeability peaked within 20 min and gradually returned to control levels in response to a 15-ng dose (submaximal dose). Increased mucosal permeability was not recovered after a 150-ng dose (ulcerogenic dose). This increase in permeability was inhibited by vagotomy or atropine. Intragastric perfusion with HCl did not change the RX-77368 (15 ng)-induced increase in permeability, but completely inhibited the recovery of permeability after the peak. Pretreatment with omeprazole did not change the RX-77368 (15 ng)-induced increase in permeability, but quickened the recovery of permeability after the peak. These data indicate that the RX-77368-induced increase in permeability is mediated via the vagal-cholinergic pathway and is not a secondary change in RX-77368-induced acid secretion. Inhibited recovery of permeability on exposure to an ulcerogenic RX-77368 dose or on exposure to HCl plus a submaximal dose of RX-77368 may be crucial for the induction of gastric mucosal lesions by central RX-77368 administration.

Although various biomaterials such as ceramics or titanium alloy are widely used in neurosurgery, the susceptibility artifacts that appear around these materials cause problems when a magnetic resonance (MR) imager is used to assess lesions after surgery. The purpose of the present study was to quantify the susceptibility artifacts produced by various biomaterials used for neurosurgical implants. Using a 3-tesla MR imaging unit, we obtained MR images of various biomaterials, including six types of ceramics, a cobalt-based alloy (Elgiloy), pure titanium, a titanium alloy, and stainless steel. All implants shared a uniform size and shape. In each image, a linear region of interest was defined across the center of the biomaterial in the transverse direction, and the diameter of the susceptibility artifact was calculated. The ceramics produced a considerably smaller artifact diameter than those produced by other biomaterials. Among the types of ceramics, zirconia was found to produce the smallest artifact diameter. Among the remaining biomaterials, the diameters of the artifacts decreased in order from that associated with stainless steel to those associated with cobalt-based alloys, pure titanium, and titanium alloy. Little difference was observed between the artifact diameters associated with pure titanium and titanium alloy. Ceramics are the most suitable biomaterials for minimizing artifacts in high-field MR imaging.

Background and Purpose: A reduction in the area of the substantia nigra (SN) has been shown in patients with Parkinson disease. The substantia nigra is anteroinferolateral to the red nucleus, and it is important to precisely locate its true anatomic location to accurately measure SN area. Our purpose was to determine the exact location of the substantia nigra by correlating imaging and anatomic findings. We also attempted to quantitate SN area in patients with Parkinson disease compared with that in healthy control subjects on the basis of proton density-weighted spin-echo (SE) and fast short inversion time inversion-recovery (STIR) MR imaging findings., Methods: In four healthy volunteers, dual-echo SE and fast STIR MR images were obtained in three orthogonal planes and an oblique coronal plane. These images were correlated with anatomic specimens to determine the location of the SN. The area of the SN was also measured on oblique coronal fast STIR images obtained at a plane perpendicular to the SN in 22 patients with Parkinson disease and in 22 age- and sex-matched healthy volunteers., Results: The true anatomic location of the SN, anteroinferolateral to the red nucleus, was accurately identified, not on T2-weighted images, but on proton density-weighted SE images and fast STIR images as an area of hyperintense gray matter. The hypointense area seen on T2-weighted images corresponded to the anterosuperior aspect of the SN and to the adjacent crus cerebri. No statistically significant differences were noted in the size of the SN when the oblique coronal images of patients with Parkinson disease were compared with those of the control groups., Conclusion: The SN is located mainly beneath the red nucleus. Its location cannot be determined on the basis of T2-weighted imaging results but rather on the basis of proton density-weighted SE or fast STIR findings. SN volume loss is not found in Parkinson disease, and this finding is compatible with that of recent pathology reports in the literature.

Characteristic pathologic changes of cranial computed tomography (CT) and magnetic resonance imaging (MRI) have never been reported in "Alice in Wonderland" syndrome (AIWS) caused by Epstein-Barr (EB) virus infection. We present here a 10-year-old girl with AIWS with an abnormal MR finding. During the course of serologically confirmed EB virus encephalopathy, she had distortion of the body image, visual hallucinations and depersonalization characteristic of AIWS. MRI demonstrated transient T2 prolongation and swelling of the cerebral cortex, especially at the bilateral temporal lobes, bilateral cingulate gyrus, right upper frontal gyrus, bilateral caudate nucleus, and bilateral putamen, whereas CT showed no abnormalities. Transient MRI lesions were occasionally reported in patients with EB virus encephalopathy/encephalitis who presented visual illusions and psychotic reactions, although the diagnosis of AIWS was not described. We consider that any patient with symptoms of AIWS should have MRI because the abnormal MRI findings may disappear in a short period.

The five questions answered in this article revolve around the different parameters resulting from perfusion imaging processing, and this clarifies the frequently confusing terminology used to describe these parameters. More specifically, the article discusses the different imaging techniques and main mathematical models behind perfusion imaging, reviews the perfusion attributes of brain tissue, and proposes a standardized parameter terminology to facilitate understanding and avoid common misinterpretations. [ABSTRACT FROM AUTHOR]

A delay-insensitive probabilistic method for estimating hemodynamic parameters, delays, theoretical residue functions, and concentration time curves by computed tomography (CT) and magnetic resonance (MR) perfusion weighted imaging is presented. Only a mild stationarity hypothesis is made beyond the standard perfusion model. New microvascular parameters with simple hemodynamic interpretation are naturally introduced. Simulations on standard digital phantoms show that the method outperforms the oscillating singular value decomposition (oSVD) method in terms of goodness-of-fit, linearity, statistical and systematic errors on all parameters, especially at low signal-to–noise ratios (SNRs). Delay is always estimated sharply with user-supplied resolution and is purely arterial, by contrast to oSVD time-to-maximum TMAX that is very noisy and biased by mean transit time (MTT), blood volume, and SNR. Residue functions and signals estimates do not suffer overfitting anymore. One CT acute stroke case confirms simulation results and highlights the ability of the method to reliably estimate MTT when SNR is low. Delays look promising for delineating the arterial occlusion territory and collateral circulation. [ABSTRACT FROM AUTHOR]