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Shared rotating control acquisition can shorten the imaging time of territorial arterial spin labeling (tASL) by 33% compared with the normal control acquisition scheme but potentially results in an inaccurate estimate of vascular territories due to imperfect magnetization transfer compensation. Our purpose was to validate the accuracy of the shared rotating control acquisition method in evaluation of vascular territories. Twenty-four patients underwent tASL at a 3.0-T MRI with the conventional normal control acquisition method. Composite vascular territory maps, in which the blood flows from the right and left internal carotid arteries and the posterior circulation were encoded in red–green–blue, were generated as a normal averaged control-label scheme and as a simulated shared rotating control scheme. Two observers independently reported the most dominant territorial flow in 26 brain regions corresponding to the arterial segments at three post-labeling time points. Inter-reader and inter-method agreements were analyzed using κ statistics. Overall inter-reader agreements were excellent for both the normal control and the shared rotating control methods (κ = 0.98, respectively). Overall inter-method agreement was also excellent (κ = 0.98), although relatively low agreement was noted in the bilateral posterior cerebral artery territories (κ = 0.79 to 0.93). Our results suggested that tASL using shared rotating control acquisition can provide information on the vascular territories comparable to that obtained using the normal control acquisition while substantially shortening the imaging time.

PURPOSE The purpose of this study was to examine interhemispheric asymmetry in volume of the caudate nucleus and its age dependency. METHODS High-resolution T1-weighted brain magnetic resonance (MR) images were obtained for each subject using a 3-dimensional fast field-echo pulse sequence. The volumes of the bilateral caudate nuclei on MR images were measured using an automated method. Right-to-left comparison was made using paired t-test. Age-related change of right-to-left volume ratio (R/L ratio) was examined using Pearson's correlation coefficient. RESULTS Fifty healthy right-handed Japanese male subjects (age 12 to 67 years, mean 39.6 years) were involved in this study. The volume of right caudate nucleus was larger than the left in 48 of 50 subjects (P < .001). R/L ratio increased with age (r= .420, P < .01). CONCLUSIONS Our results confirmed the rightward volumetric asymmetry of caudate nucleus in right-handed individuals, and revealed that this asymmetry becomes notable with age.

It is important to differentiate human herpesvirus 6 (HHV-6)-associated encephalopathy from herpes simplex encephalitis (HSE). Although these conditions are similar with regard to involvement of the mesial temporal lobe, HSE is sensitive to acyclovir but HHV-6 encephalopathy is not. We compared the imaging findings of the two conditions.We encountered eight cases of HHV-6 encephalopathy and nine cases of HSE. We divided an observation time into early, middle, and late periods defined as 0-2, 3-30, and more than 30 days from the onset of neurologic symptoms. Differences between HHV-6 encephalopathy and HSE on CT scans in the early period and in distribution and temporal changes in the affected regions on MR images in the three periods were analyzed.At MRI in the early and middle periods, all eight patients with HHV-6 encephalopathy had exclusive involvement of the mesial temporal lobes, and all nine patients with HSE had involvement of both the mesial temporal lobes and the extratemporal regions (p0.01). Among patients who underwent head MRI, six of six with HHV-6 encephalopathy but none of six with HSE had resolution of high signal intensity on T2-weighted and FLAIR images (p0.01). Among patients who underwent head CT in the early period, none of the four with HHV-6 encephalopathy and six of the seven with HSE had abnormal findings, including parenchymal swelling, decreased attenuation of affected regions, and abnormal gyral enhancement (p0.05).Serial MRI showed transient abnormal signal intensity in the mesial temporal lobes in patients with HHV-6 encephalopathy but persistent abnormal signal intensity in both the mesial temporal lobes and the extratemporal regions in patients with HSE. CT in the early period showed no abnormality in patients with HHV-6 encephalopathy but definite abnormal findings in patients with HSE. These differences may be useful in the differential diagnosis of the two conditions.

The purpose of this study was to determine whether arterial spin labelling (ASL) at 3-T MR imaging can be used to discriminate individuals with Alzheimer's disease (AD) from cognitively normal subjects. Twenty AD patients and 23 cognitively normal control subjects were studied using ASL on a 3-T MR imager. Absolute regional cerebral blood flow (rCBF) maps were calculated. In addition, normalized rCBF maps were obtained using CBF in the sensorimotor cortex for normalization. A voxel-wise comparison of these rCBF maps between the AD and control groups was performed using the two-sample t test. Individuals with AD were discriminated from control subjects based on mean rCBF values within a region-of-interest defined by the t test, and the discriminating performance was evaluated by the receiver operating characteristic (ROC) analysis. Comparisons of both absolute and normalized rCBF maps revealed areas of significant hypoperfusion caused by the effects of AD in the bilateral precunei and posterior cingulate gyri. ROC analyses resulted in area under the curve (AUC) values of 0.861 to 0.877 for absolute and 0.910 to 0.932 for normalized rCBF. Our results suggest that ASL at 3-T MR imaging can be used to help discriminate individuals with AD from normal subjects.

BACKGROUND AND PURPOSE: Cerebral hemodynamics abnormality in Alzheimer disease (AD) is not fully understood. Our aim was to determine whether regional hypoperfusion due to AD is associated with abnormalities in regional arterial blood volume (rABV) and regional arterial transit time (rATT) as measured by quantitative arterial spin-labeling (ASL) with multiple-delay time sampling. MATERIALS AND METHODS: Nineteen patients with AD (9 men and 10 women; mean age, 74.5 ± 8.6 years) and 22 cognitively healthy control subjects (11 men and 11 women; mean age, 72.8 ± 6.8 years) were studied by using a quantitative ASL method with multiple-delay time sampling. From the ASL data, maps of regional cerebral blood flow (rCBF), rABV, and rATT were generated. A region of hypoperfusion due to AD was determined by statistical parametric mapping (SPM) analysis. Mean rCBF, rABV, and rATT values within the hypoperfused region were compared between the AD and control groups. RESULTS: Despite the significantly lower rCBF ( P = .0004) in patients with AD (27.8 ± 7.1 mL/100 g/min) in comparison with control subjects (36.7 ± 6.3 mL/100 g/min), no significant difference in rATT was observed between the control (0.48 ± 0.09 seconds) and AD (0.47 ± 0.10 seconds) groups. Mean rABV was lower in the AD group (0.22 ± 0.10%) than in the control group (0.27 ± 0.12%), though the difference did not reach the level of statistical significance. CONCLUSIONS: Our results revealed that regional hypoperfusion in AD is not associated with rATT prolongation, suggesting that the mechanism of hypoperfusion is distinct from that in cerebrovascular diseases.

Hemothorax due to rupture of metastatic hepatocellular carcinoma (HCC) is a very rare complication with high mortality because of uncontrollable hemorrhage. A 71-year-old man treated by transcatheter arterial embolization for HCC with massive bleeding from chest wall metastasis is reported. Enhanced computed tomography and selective intercostal angiogram showed a hypervascular mass in the right chest wall and extravasation of contrast agent. After successful transcatheter arterial embolization with gelatin sponge particles and metallic coils, the patient recovered from shock without major complication. To our knowledge, a successfully treated case of hemothorax due to rupture of metastatic HCC has not previously been described.

We investigated the time interval from labeling to peak (TLP) of perfusion-signal intensity (SIs) in normal brain using a multiphase arterial spin-labeling (ASL) magnetic resonance imaging (MRI) technique as a fundamental study to assess the temporal characteristics of perfusion SIs.Twenty temporal phases of a pulsed ASL-MRI [QUASAR, quantitative signal targeting by alternating radiofrequency pulses (STAR) labeling of arterial regions] in single-slice imaging were performed in 9 volunteers. Perfusion SIs were measured and TLPs were calculated in 14 regions of interest (ROIs), 7 in each hemisphere: thalamus, lentiform nucleus, medial frontal cortex in the anterior cerebral artery (ACA) territory, temporal cortex in the middle cerebral artery (MCA) territory, medial occipital cortex in the posterior cerebral artery (PCA) territory, anterior watershed region (AWR) and posterior watershed region (PWR).Mean TLP varied with ROI (region and mean ± standard deviation in seconds): thalamus, 1.60 ± 0.11; lentiform nucleus, 1.52 ± 0.11; ACA territory, 1.53 ± 0.16; MCA territory, 1.59 ± 0.18; PCA territory, 1.68 ± 0.20; AWR, 1.79 ± 0.14; PWR, 2.00 ± 0.20. TLP in the PWR was significantly longer than those in all other regions except the AWR, and TLP in the AWR was significantly longer than those in the lentiform nucleus and the ACA territory.Our results revealed regional differences in the temporal characteristics of perfusion SIs on ASL-MRI.

BACKGROUND AND PURPOSE: MSDE preparation is a technique for black-blood imaging. Our purpose was to evaluate the usefulness of a 3D TSE sequence with MSDE preparation in detecting brain metastases by comparing it with conventional sequences. MATERIALS AND METHODS: Postcontrast images of 227 patients who were suspected of having brain metastasis were prospectively obtained by using 3 T1-weighted 3D sequences: a gradient-echo sequence (MPRAGE), TSE-noMSDE, and TSE-MSDE. The number of visualized blood vessels and the lesion-to-normal CNR were compared among the 3 sequences. An observer test involving 9 radiologists was performed, and their diagnostic performance by using TSE-MSDE, MPRAGE, and combined TSE-MSDE and MPRAGE was compared by means of an FOM as an index of diagnostic performance derived by the JAFROC analysis, sensitivity, FP/case, and reading time. RESULTS: TSE-MSDE resulted in significantly better vessel suppression than the other 2 methods. TSE with and without MSDE resulted in significantly higher CNRs than MPRAGE. In the observer test, significantly higher sensitivity and FOM as well as significantly shorter reading time were achieved by TSE-MSDE compared with MPRAGE, but FP/case was significantly higher with TSE-MSDE. Combined TSE-MSDE/MPRAGE resulted in significantly higher sensitivity and FOM and similar FP/case and reading time compared with MPRAGE alone. CONCLUSIONS: With blood vessel suppression and increased CNR, TSE-MSDE improves radiologists9 performances in detecting brain metastases compared with MPRAGE, but it may increase FP results. Combined with MPRAGE, TSE-MSDE achieves high diagnostic performance while maintaining a low FP rate.

Imaging has been increasingly recognized as a powerful tool for diagnosing Alzheimer's disease (AD). Magnetic resonance imaging (MRI) is advantageous over other imaging modalities due to its non-invasiveness and multi-parametric capabilities. In addition to the morphological assessment, several new MR imaging approaches have shown potential for improved AD diagnosis. This paper focuses on two of these advanced MRI-based approaches: diffusion-weighted imaging and arterial spin labeling.

Our purpose was to reveal potential regional variations in water molecular diffusivity within each cerebral hemisphere and across the right and left hemispheres. Diffusion-weighted images of 44 healthy right-handed adult male subjects were obtained using a diffusion tensor imaging sequence. Mean diffusivity (MD) values in subcortical white matter (WM) within 39 regions in each hemisphere were measured using an automated method. Intrahemispheric comparisons of MDs in subcortical WM were performed among six brain regions (frontal, parietal, occipital and temporal lobes and pre- and postcentral gyri). Interhemispheric comparisons of MDs were performed between the right and left counterparts of the 39 regions. In both hemispheres, diffusivity in the precentral gyrus was lower than those in other regions, while diffusivity in the parietal lobe was higher than others. MD asymmetry in which the left was lower than the right was found in the parietal lobe, middle occipital gyrus, and medial and orbital aspects of the frontal lobe. The converse asymmetry was revealed in the frontal operculum, supplementary motor cortex, temporal lobe, limbic cortices, precuneus and cuneus. Our results revealed significant intra- and interhemispheric regional variations in MD in subcortical WM, which may be related to different densities of axons and myelin sheaths.

BACKGROUND AND PURPOSE: We investigated the relationship between tumor blood-flow measurement based on perfusion imaging by arterial spin-labeling (ASL-PI) and histopathologic findings in brain tumors. MATERIALS AND METHODS: We used ASL-PI to examine 35 patients with brain tumors, including 11 gliomas, 9 meningiomas, 9 schwannomas, 1 diffuse large B-cell lymphoma, 4 hemangioblastomas, and 1 metastatic brain tumor. As an index of tumor perfusion, the relative signal intensity (SI) of each tumor (%Signal intensity) was determined as a percentage of the maximal SI within the tumor per averaged SI within normal cerebral gray matter on ASL-PI. Relative vascular attenuation (%Vessel) was determined as the total microvessel area per the entire tissue area on CD-34–immunostained histopathologic specimens. MIB1 indices of gliomas were also calculated. The differences in %Signal intensity among different histopathologic types and between high- and low-grade gliomas were compared. In addition, the correlations between %Signal intensity and %Vessel or MIB1 index were evaluated in gliomas. RESULTS: Statistically significant differences in %Signal intensity were observed between hemangioblastomas versus gliomas (P < .005), meningiomas (P < .05), and schwannomas (P < .005). Among gliomas, %Signal intensity was significantly higher for high-grade than for low-grade tumors (P < .05). Correlation analyses revealed significant positive correlations between %Signal intensity and %Vessel in 35 patients, including all 6 histopathologic types (rs = 0.782, P < .00005) and in gliomas (rs = 0.773, P < .05). In addition, in gliomas, %Signal intensity and MIB1 index were significantly positively correlated (rs = 0.700, P < .05). CONCLUSION: ASL-PI may predict histopathologic vascular densities of brain tumors and may be useful in distinguishing between high- and low-grade gliomas and in differentiating hemangioblastomas from other brain tumors.