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Objective To compare short-term treatment outcomes at hospital discharge and hospital length of stay (LOS) in patients with spontaneous intracerebral hemorrhage (sICH) before and after introduction of resident physician work time limit (WTL). Methods We retrospectively reviewed consecutive patients treated for sICH at our institution between 2016 and 2019. Then we dichotomized these patients into two groups, pre-WTL and post-WTL. We analyzed demographic elements and clinical features, and hospital length of stay (LOS). We evaluated short-term outcome using modified Rankin scale score at hospital discharge and then divided it into "good" and "poor" outcome groups. We subsequently, compared short-term treatment outcome and hospital LOS between the pre-WTL and post-WTL groups. Results Out of 779 patients, 420 patients (53.9%) were included in the pre-WTL group, and 359 (46.1%) in post-WTL. The mortality rate in sICH patients was higher in the post-WTL group (pre-WTL; 13.6% vs. post-WTL; 17.3%), but there was no statistically significant difference in short-term outcome including mortality (p=0.332) between the groups. The LOS also, was not significantly different between the two groups (pre-WTL; 19.0 days vs. post-WTL; 20.2 days) (p=0.341). The initial Glasgow Coma Scale score, personal stroke history, and mean age were the only independent outcome predicting factors for patients with sICH. Conclusions Some neurosurgeons may expect poorer outcome for sICH after implementation of the WTL of the K-MHW for resident physician however, enforcement of the WTL did not significantly influence the short-term outcome and hospital LOS for sICH in our hospital. Further well-designed multi-institutional prospective studies on the effects of WTL in sICH patient outcome, are anticipated.

Objective We aimed to identify the relation between perioperative cerebrospinal fluid (CSF) drain through lumbar drainage (LD) and development of postoperative (POP) remote intracerebral hemorrhage (rICH) in craniotomy to treat ruptured intracranial aneurysms. Methods We retrospectively reviewed consecutive patients who underwent craniotomy for ruptured cerebral aneurysms at the authors’ institution between 1998 and 2004. We subsequently compared the incidence and characteristics of POP rICH between the patients who had a perioperative LD and those who did not. All statistical analyses were conducted using the software package SPSS 19.0 (SPSS Inc., Chicago, IL, USA). A p value of

The output network of the basal ganglia plays an important role in motor, associative, and limbic processing and is generally characterized by the pallidothalamic and nigrothalamic pathways. However, these connections in the human brain remain difficult to elucidate because of the resolution limit of current neuroimaging techniques. The present study aimed to investigate the mesoscopic nature of these connections between the thalamus, substantia nigra pars reticulata, and globus pallidus internal segment using 7 Tesla (7T) magnetic resonance imaging (MRI). In this study, track-density imaging (TDI) of the whole human brain was employed to overcome the limitations of observing the pallidothalamic and nigrothalamic tracts. Owing to the super-resolution of the TD images, the substructures of the SN, as well as the associated tracts, were identified. This study demonstrates that 7T MRI and MR tractography can be used to visualize anatomical details, as well as 3D reconstruction, of the output projections of the basal ganglia.

The cingulum bundle (CB) is a fasciculus in the white matter surrounded by the cingulate cortex, which is generally subdivided into the anterior, middle, and posterior parts based on their function and cytology. Interestingly, the cingulate cortex can also be divided into inner and outer layers based on their gross anatomy. Herein, we analyzed the CB pathway by considering the double-layered cingulate cortex using magnetic resonance (MR) tractography data. We used 7.0T diffusion-weighted MRI data from the Human Connectome Project dataset, from which 32 individual datasets were selected. Anatomical MR images in each dataset were parcellated into the cortical subdivisions automatically using the FreeSurfer software. The seed positions in both layers of the cingulate white matter (CWM) for fiber tracking were determined based on the parcellated MR image data. The cingulate cortex with double layers was found in 46.5% of the coronal section in the cingulate cortex’s dorsal part, with many individual differences in the outer-layered CWM. Fiber extraction from each determined seed position in both layers of the CWM was carried out using the MRtrix software. The fiber tracking results indicated that the anterior and posterior areas demonstrate major cortical connectivity through the inner-layered CB and the superior area of the brain through the outer-layered CB. From the results, we designed a new CB connectivity model considering the double-layered cingulate cortex to provide a more organized insight into the function of CB function and its connectivity with the cerebral cortex.

We investigated the differential spatial covariance pattern of blood oxygen level-dependent (BOLD) responses to single-task and multitask functional magnetic resonance imaging (fMRI) between patients with psychophysiological insomnia (PI) and healthy controls (HCs), and evaluated features generated by principal component analysis (PCA) for discrimination of PI from HC, compared to features generated from BOLD responses to single-task fMRI using machine learning methods. In 19 patients with PI and 21 HCs, the mean beta value for each region of interest (ROIbval) was calculated with three contrast images (i.e., sleep-related picture, sleep-related sound, and Stroop stimuli). We performed discrimination analysis and compared with features generated from BOLD responses to single-task fMRI. We applied support vector machine analysis with a least absolute shrinkage and selection operator to evaluate five performance metrics: accuracy, recall, precision, specificity, and F2. Principal component features showed the best classification performance in all aspects of metrics compared to BOLD response to single-task fMRI. Bilateral inferior frontal gyrus (orbital), right calcarine cortex, right lingual gyrus, left inferior occipital gyrus, and left inferior temporal gyrus were identified as the most salient areas by feature selection. Our approach showed better performance in discriminating patients with PI from HCs, compared to single-task fMRI.

Demands for in-vivo human molecular imaging with high resolution and high sensitivity in positron emission tomography (PET) require several new design formulae. A classical problem of the PET design, however, was the trade-off between sensitivity and resolution. To satisfy both requirements, the brain-body convertible PET with wobbling and zooming is proposed. The features of this new proposed system are wobble sampling for high-resolution imaging and zooming mode for high sensitivity, especially for the brain dedicated imaging. For the high resolution, wobbling with a linear interpolation and line spread function (LSF) deconvolution reconstruction algorithm was introduced. The result of the proposed system provided resolution up to 1.56 mm full width at half maximum (FWHM) in the brain mode and resulting in the detector-to-resolution ratio (DRR) was 2.47. For both brain phantom and in-vivo rat brain imaging, the proposed system demonstrated superior image quality compared with the commercial PET systems. The newly designed PET with wobbling and zooming also demonstrated the possibility of developing practically usable high-resolution human brain PET-MRI fusion system, especially for the neuroscience research.

Background MR tractography from diffusion tensor imaging provides a non-invasive way to explore white matter pathways in the human brain. However, a challenge to extracting reliable anatomical information from these data is the use of reliable and effective clustering methodologies. In this paper, we implemented a new version of a robust unsupervised clustering method from MR tractography data using the density-based spatial clustering of applications with noise (DBSCAN) algorithm. New method Conventional DBSCAN clustering methods for MR tractography data use each fiber’s start and end point as well as the distance between start and end points. Instead, in this study, we extracted and used a fiber-distance matrix generated for all fiber combinations from the tractography dataset in DBSCAN clustering. The two DBSCAN parameters—minimum point number and maximum radius of the neighborhood—were selected according to the value generated with the cluster stability index (CSI). Results Performing the proposed CSI-optimized DBSCAN-based clustering method on MR tractography data of the superior longitudinal fasciculus generated 6 robust, non-overlapping, clusters that are neuroanatomically related. Comparison with existing methods Conventional DBSCAN-based clustering methods have intrinsic error potential in the clustering results due to deviations in fiber shape and fiber location. The proposed method did not exhibit clustering error caused by deviation in fiber trajectory or fiber location. Conclusions We implemented a new, robust DBSCAN-based fiber clustering method for MR tractography data. The CSI-optimized DBSCAN-based unsupervised clustering is applicable to investigation of the neuroconnectome and the fiber structure of the brain.

The Papez circuit has been considered as an important anatomical substrate involved in emotional experience. However, the circuit remains difficult to elucidate in the human brain due to the resolution limit of current neuroimaging modalities. In this article, for the first time, we report the direct visualization of the Papez circuit with 7-Tesla super-resolution magnetic resonance tractography. Two healthy, young male subjects (aged 30 and 35 years) were recruited as volunteers following the guidelines of the institutional review board (IRB). Track density imaging (TDI) generation with track tracing was performed using MRtrix software package. With these tools, we were able to visualize the entire Papez circuit. We believe this is the first study to visualize the complete loop of the Papez circuit, including the perforant path (PP), thalamocortical fibers of the anterior nucleus (AN), and mammillothalamic tract (MTT), which were hitherto difficult to visualize by conventional imaging techniques.

7 T arterial spin labeling (ASL) faces major challenges including the increased specific absorption rate (SAR) and increased B0 and B1 inhomogeneity. This work describes the design and implementation of a dual-coil system that allows for continuous ASL (CASL) at 7 T. This system consisted of an actively detunable eight-channel transceiver head coil, and a three-channel transceiver labeling coil. Four experiments were performed in 5 healthy subjects: (i) to demonstrate that active detuning during ASL labeling reduces magnetization transfer; (ii) to measure the B1 profile at the labeling plane; (iii) to quantify B0 off-resonance at the labeling plane; and (iv) to collect in vivo CASL data. The magnetization transfer ratio in the head coil was reduced to 0.0 ± 0.2% by active detuning during labeling. The measured B1 profiles in all 5 subjects were sufficient to satisfy the flow-driven adiabatic inversion necessary for CASL, however the actual labeling efficiency was significantly impacted by B0 off-resonance at the labeling plane. The measured CASL percent signal change in gray matter (0.94% ± 0.10%) corresponds with the low labeling efficiency predicted by the B0 off-resonance. This work demonstrates progress in the technical implementation of 7 T CASL, and reinforces the need for improved B0 homogeneity at the labeling plane.

Summary The purpose of this study was to combine a dual-Helmholtz (DH) transmit (Tx)-only coil and 12-channel receive (Rx)-only bended phased array (PA) coil to improve the magnetic flux (|B1|) sensitivity in the superior-to-inferior (S-I) direction during human brain magnetic resonance imaging (MRI) at 7-T. The proposed coil combination was primarily implemented by electromagnetic (EM) simulation and compared with the 16-leg birdcage coil and 8-channel PA coil, which are generally used for the Tx- and Rx-only modes, respectively. The optimal coil combinations for the proposed structure were determined by |B1| field calculations using the |BT+| and |BR−| fields, which are respectively the transmit and receive components of the |B1| field. The coil performance was then evaluated by a bench test and 7-T MRI experiment. The results of the computational calculations indicated that the |BT+| field of the DH coil was distributed similarly to that of the 16-leg birdcage coil despite the fewer conducting legs of the former. However, the 12-channel Rx-only bended PA coil had clearly higher |BR−| profiles compared to the 8-channel PA coil. The results of the 7-T in vivo experiment showed that the proposed combination of the DH Tx-only coil and 12-channel Rx-only bended PA coil had better |B1| field homogeneity in the sagittal slice as well as higher |B1| field sensitivity during human brain MRI compared to an 8-channel Rx-only PA coil. SCANNING 9999:1–10, 2015. © 2015 Wiley Periodicals, Inc.

Self-transcendence is an inherent human personality trait relating to the experience of spiritual aspects of the self. We examined the relationship between self-transcendence and serotonin transporter (SERT) availability in brainstem raphe nuclei, which are collections of five different serotonergic nuclei with rostro-caudal extension, using ultra-high resolution magnetic resonance imaging (MRI) and positron emission tomography (PET) with (11)C-3-amino-4-(2-dimethylaminomethylphenylthio)benzonitrile ([(11)C]DASB) to elucidate potential roles of serotonergic neuronal activities in this personality trait. Sixteen healthy subjects completed 7.0T MRI and High Resolution Research Tomograph (HRRT) PET. The regions of interest (ROIs) included the dorsal raphe nucleus (R1), median raphe nucleus (R2), raphe pontis (R3), and the caudal raphe nuclei (R4 and R5). For the estimation of SERT availability, the binding potential (BPND) was derived using the simplified reference tissue model (SRTM2). The Temperament and Character Inventory was used to measure self-transcendence. The analysis revealed that the self-transcendence total score had a significant negative correlation with the [(11)C]DASB BPND in the caudal raphe (R5). The subscale score for spiritual acceptance was significantly negatively correlated with the [(11)C]DASB BPND in the median raphe nucleus (R2). The results indicate that the self-transcendence trait is associated with SERT availability in specific raphe subnuclei, suggesting that the serotonin system may serve as an important biological basis for human self-transcendence. Based on the connections of these nuclei with cortico-limbic and visceral autonomic structures, the functional activity of these nuclei and their related neural circuitry may play a crucial role in the manifestation of self-transcendence.

In order to increase 1,3-BD yield, ordered mesoporous materials (OMMs) was synthesized and used as supporting materials of heterogeneous catalysts for ethanol conversion into 1,3-BD. To make acidic and basic sites acting as active sites on the surface of catalysts, a moderate (5 wt%) amount of zinc oxide (ZnO) and zirconium oxide (ZrO2) were impregnated on as-prepared various supporting materials at a time. Prepared catalysts showed different acid-base properties according to used supporting materials. The ordered mesoporous silicas (OMSs) based catalysts were proven to exhibit higher ethanol conversions and 1,3-BD selectivities because they have not only adequate number and strength of acidic sites and basic sites but also very regular mesoporous structure. Especially ZnO-ZrO2/KIT-6 revealed a higher 1,3-BD selectivity above 54.0% at ethanol conversion of 82.5% at 400 °C. On the other hand, the selectivity of diethylether (DEE) was grown to over 68% in the case of ordered mesoporous alumina (OMA) based catalyst for example ZnO-ZrO2/OMA catalyst with a higher ethanol conversion above 80% at the same temperature. A similar type of catalyst with the ZnO-ZrO2/KIT-6, ZnO-ZrO2/a-SiO2 exhibited relatively low ethanol conversion and selectivity toward 1,3-BD. Through these results, it was confirmed that adequate number and strength of strong acidic and basic sites are key factors for full conversion of ethanol to 1,3-BD with well-developed ordered mesoporous structure.

AIM The aim of this study was to assess neuropsychological correlations with the T2* relaxation time (T2*-RT) of hippocampal subregions in adolescents using ultra-high-field (UHF) 7.0-T magnetic resonance imaging (MRI). METHODS We assessed the T2*-RT of hippocampal subregions in 31 healthy 11th- or 12th-grade high school students using an UHF 7.0-T MRI system. T2*-RT of the cornu ammonis (CA) 1, CA2, CA3, and CA4 subregions and the subiculum were calculated for both the left and right hippocampus. Seven subtests of the Cambridge Neuropsychological Test Automated Battery were administered to the subjects to assess visuospatial memory. RESULTS Poor performances in delayed recall in the pattern-recognition test were significantly correlated with longer T2*-RT in the bilateral subiculum (right, r = -0.480, P = 0.006; left, r = -0.648, P

Objective The aim of this study was to assess the benefit of using a prophylactic surgical site closed suction drain in pterional craniotomy. Materials and Methods A retrospective review was conducted on 607 consecutive patients who underwent a pterional craniotomy for treatment of intracranial anterior circulation aneurysms over a 5-year period. Between January 2000 and December 2004, 607 patients were divided into two groups, those who had a prophylactic suction drain during closure of the surgical site (drain group, DG) and those who did not (non-drain group, NDG). Head computed tomography (CT) was taken routinely on postoperative day (POD) 1, 7, and 14. Patients' demographics, incidence of surgical site complications, and courses of surgical site healing which were evaluated radiologically by the thickness of the surgical site myocutaneous layer, were analyzed between DG and NDG. Results Patients' demographics and characteristics did not differ significantly between the two groups. The head CT showed that the degree of changes in the postoperative surgical site thickness was 148% at POD 1, 209% at POD 7, and 198% at POD 14 in DG, and 118% at POD 1, 152% at POD 7, and 158% at POD 14 in NDG compared to the preoperative value. Postoperative surgical site hematoma was 7.9% (22/274) in DG and 2.4% (8/333) in NDG. Conclusion Prophylactic use of an epidural and/or subgaleal closed suction drain does not appear to be necessary for prevention of postoperative surgical site hematoma as well as for promotion of surgical site healing in pterional craniotomy.

Purpose To propose a new Extended Monopole antenna Array with individual Shields (EMAS) coil that improves the B1 field coverage and uniformity along the z-direction. Methods To increase the spatial coverage of Monopole antenna Array (MA) coil, each monopole antenna was shielded and extended in length. Performance of this new coil, which is referred to as EMAS coil, was compared with the original MA coil and an Extended Monopole antenna Array coil with no shield (EMA). For comparison, flip angle, signal-to-noise ratio (SNR), and receive sensitivity maps were measured at multiple regions of interest (ROIs) in the brain. Results The EMAS coil demonstrated substantially larger flip angle and receive sensitivity than the MA and EMA coils in the inferior aspect of the brain. In the brainstem ROI, for example, the flip angle in the EMAS coil was increased by 45.5% (or 60.0%) and the receive sensitivity was increased by 26.9% (or 14.9%), resulting in an SNR gain of 84.8% (or 76.3%) when compared with the MA coil (or EMA). Conclusion The EMAS coil provided 25.7% (or 24.4%) more uniform B1+ field distribution compared with the MA (or EMA) coil in sagittal. The EMAS coil successfully extended the imaging volume in lower part of the brain. Magn Reson Med 75:2566–2572, 2016. © 2015 Wiley Periodicals, Inc.

Purpose The purpose of this study was to measure the velocity and direction of blood flow in microvessels, such as lenticulostriate arteries (LSAs), using PC MRA. Methods Eleven healthy subjects were scanned with 7 Tesla (T) MRI. Three velocity encoding (VENC) values of 15, 50, and 100 cm/s were tested for detecting the flow velocity in LSAs. The flow directions in Circle of Willis (CoW) were also examined with images obtained by the proposed method. Three subjects were also scanned with 3T MRI to determine the possibility of velocity measurement in LSAs. Difference between 3T and 7T was quantitatively analyzed in terms of signal-to-noise ratio and velocities in vessels and static tissues. Results In 7T MRI, use of VENC = 15 cm/s provided great visualization and velocity measurements in small and slow flowing vessels, such as the LSAs. The mean of peak velocities in LSAs was 9.61 ± 1.78 cm/s. The results obtained with low VENC also clearly depicted the directions of flow in CoW, especially in posterior communicating arteries. However, 3T MRI could not detect the velocity of blood flow in LSAs. Conclusion This study demonstrated the potential for measuring the velocity and direction of blood flow in the targeted microvessels using an appropriate VENC and 7T MRI. Magn Reson Med, 2015. © 2015 Wiley Periodicals, Inc.

An ultra-high-field magnetic resonance (MR) scanner and a specially-optimized radiofrequency (RF) coil and sequence protocol are required to obtain high-resolution images of the inner ear that can noninvasively confirm pathologic diagnoses. In phantom studies, the MR signal distribution of the gradient echo MR images generated by using a customized RF coil was compared with that of a commercial volume coil. The MR signal intensity of the customized RF coil decreases rapidly from near the RF coil plane toward the exterior of the phantom. However, the signal sensitivity of this coil is superior on both sides of the phantom, corresponding to the petrous pyramid. In in-vivo 7-T MR imaging, a customized RF coil and a volumetric-interpolated breath-hold examination imaging sequence are employed for visualization of the inner ear’s structure. The entire membranous portion of the cochlear and the three semicircular canals, including the ductus reunions, oval window, and round window with associated nervous tissue, were clearly depicted with sufficient spatial coverage for adequate inspection of the surrounding anatomy. Developments from a new perspective to inner ear imaging using the 7-T modality could lead to further improved image sensitivity and, thus, enable ultra-structural MR imaging.

Visualization of the membranous structures of the inner ear has been limited to the detection of the normal fluid signal intensity within the bony labyrinth by using magnetic resonance imaging (MRI) equipped with a 1.5 Tesla (T) magnet. High-field (HF) MRI has been available for more than a decade, and numerous studies have documented its significant advantages over conventional MRI with regards to its use in basic scientific research and routine clinical assessments. No previous studies of the inner ear by using HF MRI have been reported, in part because high-quality resolution of mastoid pneumatization is challenging due to artifacts generated in the HF environment and insufficient performance of radiofrequency (RF) coils. Therefore, a hybrid RF coil with integrated circuitry was developed at 7 T and was targeted for anatomical imaging to achieve a high resolution image of the structure of the human inner ear, excluding the bony portion. The inner-ear’s structure is composed of soft tissues containing hydrogen ions and includes the membranous labyrinth, endolymphatic space, perilymphatic space, and cochlear-vestibular nerves. Visualization of the inner-ear’s anatomy was performed in-vivo with a custom-designed hybrid RF coil and a specific imaging protocol based on an interpolated breath-held examination sequence. The comparative signal intensity value at 30-mm away from the phantom side was 88% higher for the hybrid RF coil and 24% higher for the 8-channel transmit/receive (Tx/Rx) coil than for the commercial birdcage coil. The optimized MRI protocol employed a hybrid RF coil because it enabled high-resolution imaging of the inner-ear’s anatomy and accurate mapping of structures including the cochlea and the semicircular canals. These results indicate that 7 T MRI achieves high spatial resolution visualization of the inner-ear’s anatomy. Therefore, MRI imaging using a hybrid RF coil at 7 T could provide a powerful tool for clinical investigations of petrous pathologies of the inner ear.

The serotonin transporter (SERT) is an integral protein that provides an index of serotonergic innervation. Until recently, few studies have investigated SERT binding in thalamic subregions in schizophrenia. The purpose of this study was to examine SERT availability in thalamic subdivisions (anterior nucleus, mediodorsal nucleus, and pulvinar) using 7.0-T magnetic resonance imaging (MRI) and high-resolution positron emission tomography (PET) with (11)C-3-amino-4-(2-dimethylaminomethylphenylthio)benzonitrile ([(11)C]DASB) in schizophrenia. Antipsychotic-free patients with schizophrenia (n=12) and healthy controls (n=15) underwent PET and MRI scans. For SERT availability, the binding potential with respect to non-displaceable compartment (BPND) was derived using the simplified reference tissue model (SRTM2). The analysis revealed that there were no significant differences in SERT availability between the two groups. In patients with schizophrenia, the severity of negative symptoms had a negative correlation with SERT availability in the anterior nucleus of the left thalamus. The present study did not reveal significant differences in SERT availability in thalamic subdivisions between patients with schizophrenia and control subjects. The association of SERT availability in the anterior nucleus with negative symptoms may suggest a role for the anterior thalamic nucleus in the pathophysiology of symptoms of schizophrenia. The ultra-high resolution imaging system could be an important asset for in vivo psychiatric research by combining structural and molecular information.

Here, we have employed recently developed super-resolution tractography using 7.0T-MRI to analyze the fine structures involved in thalamocortical connections, something that has proved difficult using conventional techniques. We detail a newly observed thalamocortical pathway connecting the anterior nucleus of the thalamus and the cingulate cortex not via the internal capsule but via the septal area. The observed pathway is believed to be a classical pathway of the Papez circuit but had not been previously identified.

Background and Purpose Atrophy of the hippocampus is an important clinical diagnostic marker of Alzheimer's disease (AD), and so assessments of hippocampal activity and its subdivisions might provide invaluable information. This study compared the glucose metabolism of hippocampal subdivisions in mild-AD patients and healthy controls. Methods High-resolution T2*-weighted gradient-echo magnetic resonance imaging (MRI) images and 18F-fluorodeoxyglucose (FDG) positron-emission tomography (PET) images were acquired using 7.0-T MRI and high-resolution research tomograph FDG-PET, respectively, in 9 early-stage AD patients and 10 healthy subjects. The hippocampal body was divided into three equal parts (anterior, middle, and posterior), and in each part a region of interest (ROI) was drawn over the cornus ammonis (CA)1, CA2/3, CA4/dentate gyrus (DG), and subiculum. The standardized uptake values of the hippocampal subdivisions were calculated for each ROI as ratios relative to the pons standardized uptake value. Statistical analysis was conducted using the Mann-Whitney U test. Results Patients with early-stage AD patients showed significantly less metabolic activity than healthy controls focally in the middle (p=0.050) and posterior (p=0.034) CA2/3 regions of the right hippocampus, and significantly less activity throughout the left hippocampal body in the anterior CA2/3 (p=0.027) and CA4/DG (p=0.027) regions, the middle CA1 region (p=0.011), and the posterior CA1 (p=0.034), CA2/3 (p=0.007), and CA4/DG (p=0.014) regions. Conclusions It was possible to use high-resolution PET-MRI fusion images to identify hippocampus subdivisions and assess glucose metabolism in the subfields. Reductions in metabolic activity were found to vary along the hippocampal axis in early-stage AD patients.

Neurolinguistic circuitry for two different scripts of language, such as phonological scripts (PhonoS) versus logographic scripts (LogoS) (e.g., English versus Chinese, resp.), recruits segregated neural pathways according to orthographic regularity (OrthoR). The purpose of this study was to identify the effect of VSF for cortical representation according to different OrthoR to represent Hangul versus Hanja as PhonoS versus LogoS, respectively. A total of 24 right-handed, native Korean undergraduate students with the first language of PhonoS and the second language of LogoS were divided into high- or low-competent groups for L2 of LogoS. The implicit word reading task was performed using Hanja and Hangul scripts during functional magnetic resonance imaging (fMRI) acquisition. Fluctuations of fMRI BOLD signal demonstrated that the LogoS was associated with the ventral pathway, whereas PhonoS was associated with the dorsal pathway. By interaction analysis, compared with high-competent group, low-competent group showed significantly greater activation for Hanja than for Hangul reading in the right superior parietal lobule area and the left supplementary motor area, which might be due to neural efficiency such as attention and cognition rather than core neurolinguistic neural demand like OrthoR processing.

Surgical or endovascular approaches have proved effective for large-vessel diseases over the past decade. However, approaches for small vessel diseases are unlikely to be accomplished by those for large vessels and only few have been applied, because it is hard to access to those small vessels and one could not directly delineate the affected small vessels due to a lack of detection modalities. This study is to examine patients with vascular diseases using ultra-high field 7T MRI with conventional time-of-flight TOF sequence, 3D fast low-angle shot FLASH gradient-echo. We have evaluated several radio-frequency RF coils to find the optimal one for 7T magnetic resonance angiography MRA, especially for micro-vascular imaging. We have conducted several comparison studies with vascular disease patients. The results showed that micro-vessels such as lenticulostriate arteries in the subjects with risk factors like hypertension or stroke patients were significantly less than in the healthy subjects. 7T MRA images in steno-occlusive patients also showed clearly numerous collateral vessels not visible by 1.5T or 3T MRA. Furthermore, 7T MRA images were comparable to those obtained by digital subtraction angiography DSA, particularly for micro-vascular imaging. In this article, we would like to share the clinical experiences on 7T MRA that vascular images of 7T MRA were superior to conventional angiography images including 1.5T and 3T MRA, and even comparable to DSA. We also expect that further technical development and clinical applications of 7T MRA would be a clinically important diagnostic tool, in terms of an early detection of the stroke in a totally non-invasive manner. © 2014 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 24, 121-128, 2014

The effect of caffeine as a cognitive enhancer is well known; however, caffeine-induced changes in the cortical regions are still not very clear. Therefore, in this study, we conducted an investigation of the activation and deactivation with blood-oxygenation-level-dependent (BOLD) functional magnetic resonance imaging (fMRI) and of metabolic activity change with positron emission tomography (PET) in the human brain. Fourteen healthy subjects performed a visuomotor task inducing attention with 3T MRI, and PET imaging was also carried out in seven subjects to determine the cerebral glucose metabolic changes of caffeine at rest. The result by fMRI showed increased BOLD activation in the left cerebellum, putamen, insula, thalamus and the right primary motor cortex, and decreased BOLD deactivation in the posterior medial and the left posterior lateral cortex. Also, the resting state PET data showed reduced metabolic activity in the putamen, caudate nucleus, insula, pallidum and posterior medial cortex. The common cortical regions between fMRI and PET, such as putamen, insula and posterior medial cortex, where significant changes occurred after caffeine ingestion, are well known to play an important role in cognitive function like attention. This result suggests that the effect of caffeine as a cognitive enhancer is derived by modulating the attentional areas.

Purpose We have developed and evaluated a monopole antenna array that can increase sensitivity at the center of the brain for 7T MRI applications. Methods We have developed a monopole antenna array that has half the length of a conventional dipole antenna with eight channels for brain imaging with a 7T MRI. The eight-channel monopole antenna array and conventional eight-channel transceiver surface coil array were evaluated and compared in terms of transmit properties, specific absorption ratio (SAR), and sensitivity. The sensitivity maps were generated by dividing the SNR map by the flip angle distribution. Results A single surface coil provides asymmetric sensitivity resulting in reduced sensitivity at the center of the brain. In contrast, a single monopole antenna provides higher sensitivity at the center of the brain. Moreover, the monopole antenna array provides uniform sensitivity over the entire brain, and the sensitivity gain was 1.5 times higher at the center of the brain compared with the surface coil array. Conclusion The monopole antenna array is a promising candidate for MRI applications, especially for brain imaging in a 7T MRI because it provides increased sensitivity at the center of the brain. Magn Reson Med 71:1944–1952, 2014. © 2013 Wiley Periodicals, Inc.

ObjectiveHuman impulsivity is a complex multidimensional construct encompassing cognitive, emotional, and behavioural aspects. Previous animal studies have suggested that striatal dopamine receptors play a critical role in impulsivity. In this study, we investigated the relationship between self-reported impulsiveness and dopamine D2/3 receptor availability in striatal subdivisions in healthy subjects using high-resolution positron emission tomography (PET) with [11C]raclopride.MethodsTwenty-one participants completed 3-T magnetic resonance imaging and high-resolution PET scans with [11C]raclopride. The trait of impulsiveness was measured using the Barratt Impulsiveness Scale (BIS-11). Partial correlation analysis was performed between BIS-11 scores and D2/3 receptor availability in striatal subregions, controlling for the confounding effects of temperament characteristics that are conceptually or empirically related to dopamine, which were measured by the Temperament and Character Inventory.ResultsThe analysis revealed that the non-planning (p = 0.004) and attentional (p = 0.007) impulsiveness subscale scores on the BIS-11 had significant positive correlations with D2/3 receptor availability in the pre-commissural dorsal caudate. There was a tendency towards positive correlation between non-planning impulsiveness score and D2/3 receptor availability in the post-commissural caudate.ConclusionThese results suggest that cognitive subtrait of impulsivity is associated with D2/3 receptor availability in the associative striatum that plays a critical role in cognitive processes involving attention to detail, judgement of alternative outcomes, and inhibitory control.

Recent MRI studies have demonstrated that the relative orientation of white matter fibers to the B 0 field significantly affects R 2 ⁎ measurement. In this work, the origin of this effect was investigated by measuring R 2 and R 2 ⁎ in multiple orientations and fitting the results to magnetic susceptibility-based models and magic angle-based models. To further explore the source of magnetic susceptibility effect, the contribution of tissue iron to the orientation dependent R 2 ⁎ contrast was investigated. Additionally, the effects of temperature on R 2 ⁎ and orientation dependent R 2 ⁎ contrasts were studied to understand the differences reported between a fixed specimen at room temperature and in vivo at body temperature. The results suggest that the B 0 dependent R 2 ⁎ variation is better explained by the magnetic susceptibility-based model with susceptibility anisotropy. However, extracting tissue iron did not reduce the orientation dependent R 2 ⁎ contrast, suggesting iron is not the origin of the contrast. This leaves susceptibility effects from myelin as the most probable origin of the contrast. Temperature showed large contribution on both R 2 ⁎ and orientation dependent R 2 ⁎ contrasts, explaining a portion of the contrast difference between the in-vivo and in-vitro conditions.

The fusiform face area, a high-level visual area, is pivotal in processing facial information. This area receives inputs from the left and right visual fields unlike the primary visual area, which only receives inputs from its contralateral visual field. Response of the fusiform face area to ipsilateral stimulation depends on the signals crossing over at the corpus callosum. We investigated the distribution of voxel-wise activation to determine whether ipsilateral-dominant voxels exist in the fusiform face area using high spatial resolution functional MRI at 7 T. We further examined the possible functional differences between ipsilateral-dominant and contralateral-dominant voxels. By unilateral visual field stimulation, we detected ipsilateral-dominant voxels in the right fusiform face area. Their distribution was spatially heterogeneous. We tested upright and inverted facial stimulation confined to unilateral visual fields and found that these ipsilateral-dominant voxels had a different functional nature from contralateral-dominant voxels.

To improve the radiofrequency (RF) field strength and uniformity in a local imaging region, individual RF transmitting phases were controlled in surface coil elements in a 7T transceive array coil; the RF field distribution was compared with the conventional in-phase approach at 7 T. Optimal RF transmitting phases in the individual coil elements in a four-channel transceive array coil were numerically calculated using the electromagnetic (EM) field solver to obtain uniform RF field in a local imaging region. In 7 T phantom experiments, the RF field uniformity and mean SNR were evaluated on gradient echo images. In addition, a flip angle map was obtained by the double angle method. Experimental results clearly show that the EM calculation yielded an improved RF field strength and uniformity in the specific imaging region along the center of the coil array when the RF transmitting phase offset was 180° between the left and right rows of surface coil elements. In a 7 T experiment, B1 field uniformity and mean SNR with this phase offset were better than the other cases and the FA map showed a more focused and symmetric distribution as compared to other cases. Even though the RF field distribution in the transceive array coil is still strongly affected by dielectric properties at 7 T, the 180° phase offset between the left and right rows of the coil elements gave the highest magnetic flux density in the specific imaging.

7 T arterial spin labeling (ASL) faces major challenges including the increased specific absorption rate (SAR) and increased B0 and B1 inhomogeneity. This work describes the design and implementation of a dual-coil system that allows for continuous ASL (CASL) at 7 T. This system consisted of an actively detunable eight-channel transceiver head coil, and a three-channel transceiver labeling coil. Four experiments were performed in 5 healthy subjects: (i) to demonstrate that active detuning during ASL labeling reduces magnetization transfer; (ii) to measure the B1 profile at the labeling plane; (iii) to quantify B0 off-resonance at the labeling plane; and (iv) to collect in vivo CASL data. The magnetization transfer ratio in the head coil was reduced to 0.0 ± 0.2% by active detuning during labeling. The measured B1 profiles in all 5 subjects were sufficient to satisfy the flow-driven adiabatic inversion necessary for CASL, however the actual labeling efficiency was significantly impacted by B0 off-resonance at the labeling plane. The measured CASL percent signal change in gray matter (0.94% ± 0.10%) corresponds with the low labeling efficiency predicted by the B0 off-resonance. This work demonstrates progress in the technical implementation of 7 T CASL, and reinforces the need for improved B0 homogeneity at the labeling plane.

Over the past few decades, vascular flow-dependent imaging techniques have proven to be effective for the visualization of large vessel diseases. However, these approaches are unlikely to be efficacious for small vessels because the affected small vessels cannot always be visualized directly, owing to a lack of detection sensitivity. Recently, many researchers have introduced state-of-the-art imaging techniques to visualize cerebral microvessels using ultra-high-field (UHF) magnetic resonance angiography (MRA). They have demonstrated the superiority of UHF MRA, especially for visualization of the microvasculature compared with clinical MRA images using 1.5T or 3T magnetic resonance imaging (MRI). Thus, UHF MRA may become an important investigative tool for research, facilitating examinations of vascular mechanisms for small vessel diseases and contributing to the early detection of cerebrovascular diseases in clinics. Furthermore, new imaging methods for visualizing vascular dynamics or flow effects may help investigate brain functions, especially in conjunction with blood oxygenation level-dependent contrast functional MRI modalities, as well as situations in which small vessel abnormalities are clinically important. The present article reviews recent technological advances in UHF MRA, especially 7T MRA, and discusses the potential benefits and future directions of UHF MRA.

The effects of caffeine on cognitive function have been investigated with pharmaceutical and metabolic activities, providing the enhanced cognitive performance, such as working memory and sustained attention. In this chapter, caffeine-induced changes in the cortical regions are investigated using functional imaging techniques, such as blood oxygenation level-dependent functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) in the human brain. The common cortical regions between fMRI and PET, such as putamen, insula, and posterior medial cortex, where significant changes occurred after caffeine ingestion, are well known to play an important role in cognitive function like attention. This suggests that the effect of caffeine correlates with the reduced metabolism in the basal ganglia and default mode network, derived by modulating the attentional areas.

The thalamus is one of the most important brain structures, with strong connections between subcortical and cortical areas of the brain. Most of the incoming information to the cortex passes through the thalamus. Accurate identification of substructures of the thalamus is therefore of great im- portance for the understanding of human brain connectivity. Direct visualization of thalamic substruc- tures, however, is not easily achieved with currently available magnetic resonance imaging (MRI), including ultra-high field MRI such as 7.0T, mainly due to the limited contrast between the relevant structures. Recently, improvements in ultra-high field 7.0T MRI have opened the possibility of observ- ing thalamic substructures by well-adjusted high-resolution T1-weighted imaging. Moreover, the recently developed super-resolution track-density imaging (TDI) technique, based on results from whole-brain fiber-tracking, produces images with sub-millimeter resolution. These two methods enable us to show markedly improved anatomical detail of the substructures of the thalamus, including their detailed locations and directionality. In this study, we demonstrate the role of TDI for the visualization of the substructures of the thalamic nuclei, and relate these images to T1-weighted imaging at 7.0T MRI. Hum Brain Mapp 34:2538-2548, 2013. V C 2012 Wiley Periodicals, Inc.