Estimating Flow Direction of Circle of Willis Using Dynamic Arterial Spin Labeling Magnetic Resonance Angiography.

BACKGROUND AND PURPOSE: The Circle of Willis (COW) is a crucial mechanism for cerebral collateral circulation. This proof-ofconcept study aims to develop and assess an analysis method to characterize the hemodynamics of the arterial segments in COW using arterial spin labeling (ASL) based non-contrast enhanced dynamic magnetic resonance angiography (dMRA). MATERIALS AND METHODS: The developed analysis method uses a graph model, bootstrap strategy, and ensemble learning methodologies to determine the time-curve shift from ASL dMRA to estimate the flow direction within the COW. The performance of the method was assessed on 52 subjects, using the flow direction, either antegrade or retrograde, derived from 3D phase contrast (PC) MRI as the reference. RESULTS: A total of 340 arterial segments in COW were evaluated, among which 30 (8.8%) had retrograde flow according to 3D PC. The ASL dMRA-based flow direction estimation has an accuracy, sensitivity, and specificity of 95.47%, 80%, and 96.34%, respectively. CONCLUSIONS: Using ASL dMRA and the developed image analysis method to estimate the flow direction in COW is feasible. This study provides a new method to assess the hemodynamics of the COW, which could be useful for the diagnosis and study of cerebrovascular diseases. ABBREVIATIONS: COW = Circle of Willis; ASL = arterial spin labeling; dMRA =dynamic magnetic resonance angiography; PC = phase contrast.

Accurate and robust segmentation of cerebral vasculature on four-dimensional arterial spin labeling magnetic resonance angiography using machine-learning approach.

Segmentation of cerebral vasculature on MR vascular images is of great significance for clinical application and research. However, the existing cerebrovascular segmentation approaches are limited due to insufficient image contrast and complicated algorithms. This study aims to explore the potential of the emerging four-dimensional arterial spin labeling magnetic resonance angiography (4D ASL-MRA) technique for fast and accurate cerebrovascular segmentation with a simple machine-learning approach. Nine temporal features were extracted from the intensity-time signal of each voxel, and eight spatial features from the neighboring voxels. Then, the unsupervised outlier detection algorithm, i.e. Isolation Forest, is used for segmentation of the vascular voxels based on the extracted features. The total length of the centerlines of the intracranial arterial vasculature, the dice similarity coefficient (DSC), and the average Hausdorff Distance (AVGHD) on the cross-sections of small- to large-sized vessels were calculated to evaluate the performance of the segmentation approach on 4D ASL-MRA of 18 subjects. Experiments show that the temporal information on 4D ASL-MRA can largely improve the segmentation performance. In addition, the proposed segmentation approach outperforms the traditional methods that were performed on the 3D image (i.e. the temporal average intensity projection of 4D ASL-MRA) and the previously proposed frame-wise approach. In conclusion, this study demonstrates that accurate and robust segmentation of cerebral vasculature is achievable on 4D ASL-MRA by using a simple machine-learning approach with appropriate features.

Intractable epilepsy due to angiocentric glioma: A case report and minireview.

The aim of this case report and minireview was to investigate the diagnosis of and therapeutic approaches for angiocentric glioma (AG) and to summarize the clinical manifestations and the pathological and imaging characteristics of the disease. Intraoperative cortical electroencephalogram (ECoG) monitoring was performed to locate the epileptic foci in a child with AG who presented with intractable epilepsy, prior to the total resection of the tumor being performed under the microscope. The clinical features, imaging characteristics, intraoperative conditions, surgical methods and pathological results were analyzed and compared with the literature. The review revealed that to date, the clinical features of the 52 reported cases of AG (including this case) have been mainly characterized by epilepsy. High T2-weighted image (WI) and fluid-attenuated inversion recovery (FLAIR) signals may be detected with magnetic resonance imaging (MRI) scanning of the cranium; however, no enhancement signals are detected by enhanced scanning. The prognosis following surgical resection is favorable. The lesions in the present case demonstrated clear boundaries with a central cystic affection accompanied by an arachnoid cyst on the left temporal pole. Pathological examination revealed that the lesion was positive for glial fibrillary acidic protein (GFAP), S-100 protein, vimentin, epithelial membrane antigen (EMA), cluster of differentiation 99 (CD99) and D2-40. The Ki-67/MIBk-1 labeling index was ~1%. In conclusion, AG exhibits characteristic features in imaging; however, its diagnosis depends on histopathological examination. The prognosis of total surgical resection is good and intraoperative ECoG may be used to assist positioning.

Histopathologic amelioration of fibroproliferative change in rat irradiated lung using soluble transforming growth factor-beta (TGF-beta) receptor mediated by adenoviral vector.

PURPOSE: To investigate whether an adenoviral-mediated soluble transforming growth factor-beta (TGF-beta) type II receptor could ameliorate fibroproliferative change in rat irradiated lung. METHODS AND MATERIALS: We used an adenoviral vector expressing a soluble TGF-beta receptor (AdT beta-ExR), which adsorbs TGF-beta and inhibits the function of the wild-type receptor as a dominant-negative mutant. Rats were i.v. injected with either 0.5 mL of AdT beta-ExR (1.0 x 10(9) plaque-forming units/mL) or AdLacZ (1.0 x 10(9) plaque-forming units/mL), a control adenovirus expressing bacterial beta-galactosidase, or saline, then 3 days later they received 4-MV X-ray irradiation of 30 Gy in a single fraction to the right lung. Eight weeks after irradiation, the rats were killed, and their right lungs were examined histopathologically. The respiratory rates of all rats were observed with a charge-coupled device video system before the rats were irradiated and killed. RESULTS: A significant increase in breathing rates was observed in the saline- or AdLacZ-infected rats. The respiratory rate of the AdT beta-ExR-treated rats was significantly lower than that in the saline- or AdLacZ-infected rats. Fibroproliferative change in the irradiated lung was markedly reduced in the AdT beta-ExR-treated rats in comparison with the saline- or AdLacZ-infected rats. With respect to active TGF-beta 1 expression, myofibroblast proliferation, and macrophage/monocyte infiltration, the findings were identical to those for fibroproliferative change. CONCLUSIONS: Our results indicate that TGF-beta plays a critical role in radiation-induced fibroproliferation of the lung and suggest that the adenoviral-mediated soluble TGF-beta receptor may have potential for use in the amelioration of this intractable pulmonary damage.

Combined argatroban and edaravone caused additive neuroprotection against 15 min of forebrain ischemia in gerbils.

We investigated whether or not a combination of the selective thrombin inhibitor, argatroban, and the free radical scavenger, edaravone (MCI-186), ameliorates postischemic hypoperfusion and decreases mortality after 15 min of forebrain ischemia in the gerbil. Argatroban or edaravone alone significantly increased postischemic cerebral blood flow and attenuated brain edema after reperfusion. However, only the combination increased the survival ratio (P<0.05 by Mantel-Cox) and protected the damage of neuronal cells. The present study indicates that anticoagulants and free radical scavengers reciprocally function to inhibit the progression of ischemic cell damage and that a combination of these types of drugs will help to improve the outcomes after cerebral ischemia.