Visualization Of Intracranial Arteries Research Articles

Vessel Wall Magnetic Resonance Imaging in Cerebrovascular Diseases.

Cerebrovascular diseases are a leading cause of disability and death worldwide. The definition of stroke etiology is mandatory to predict outcome and guide therapeutic decisions. The diagnosis of pathological processes involving intracranial arteries is especially challenging, and the visualization of intracranial arteries’ vessel walls is not possible with routine imaging techniques. Vessel wall magnetic resonance imaging (VW-MRI) uses high-resolution, multiparametric MRI sequences to directly visualize intracranial arteries walls and their pathological alterations, allowing a better characterization of their pathology. VW-MRI demonstrated a wide range of clinical applications in acute cerebrovascular disease. Above all, it can be of great utility in the differential diagnosis of atherosclerotic and non-atherosclerotic intracranial vasculopathies. Additionally, it can be useful in the risk stratification of intracranial atherosclerotic lesions and to assess the risk of rupture of intracranial aneurysms. Recent advances in MRI technology made it more available, but larger studies are still needed to maximize its use in daily clinical practice.

Comparison Between Transcranial Color-Coded Duplex Doppler and Contrast Enhanced Transcranial Color-Coded Duplex Doppler After Subarachnoid Aneurysmal Hemorrhage.

Transcranial color-coded duplex Doppler (TCCD) is commonly used to detect and monitor vasospasm in subarachnoid aneurysmal hemorrhage (aSAH). However, contrast enhanced TCCD (CE-TCCD) may be more effective. The objective of this study was to compare the accuracy of TCCD and CE-TCCD in the detection of vasospasm. This study was a prospective comparison of TCCD and CE-TCCD for the detection of vasospasm, using computed tomography angiography (CT Angio)as a reference examination. The setting was the Department of Anesthesiology and Intensive Care at the Bicêtre University Hospital in Le Kremlin Bicêtre, France. TCCD and CE-TCCD were performed in 47 patients admitted to the intensive care unit (ICU) following aSAH over a 7-month period. TCCD and CE-TCCD were performed at ICU admission and between days 7 and 10. We aimed to visualize the seven intracranial arteries of the circle of Willis. Vasospasm diagnosis was assessed byCT Angio and graded as moderate when the percentage change in arterial diameter since admission was between 25 and 50% or as severe when the percentage change was greater than 50%. On ICU admission, TCCD allowed visualization of all intracranial arteries in 16 (34%) of 47 patients, whereas CE-TCCD allowed visualization of all vessels in 37 (79%) of 47 patients (p < 0.001). These results were consistent between days 7 and 10. The proportions of middle cerebral arteries (MCAs), anterior cerebral arteries(ACAs) and posterior cerebral arteries(PCAs) visualized were greater with CE-TCCD. There was no difference in the visualization of basilar arteries(BAs). We performed vasospasm analysis on 67 of 94 MCAs in 47 patients. Area under the curve(AUC) of mean flow velocity to detect MCA vasospasm (moderate and severe) was 0.86 (0.58-1.00) for TCCD and 0.90 (0.77-1.00) for CE-TCCD. AUC of mean velocity to detect severe MCA vasospasm was 0.86 (0.58-1.00) for TCCD and 0.90 (0.77-1.00) for CE-TCCD, without any significant difference between the two techniques. For other arteries, the accuracy of TCCD and CE-TCCD to diagnose vasospasm was poor. CE-TCCD allows better visualization of intracranial arteries in patients with aSAH. The accuracy of CE-TCCD to screen severe MCA vasospasm is similar to that of TCCD. CE-TCCD is an alternative tool for monitoring patients with aSAH without a temporal bone window for an ultrasound.

Fast acceleration of ASL-based time-resolved magnetic resonance angiography by acquisition of control and labeled images in the same shot (fast ACTRESS): An optimization study

PurposeTo establish an optimized sequence design for fast acceleration of arterial spin labeling (ASL)-based time-resolved magnetic resonance angiography (MRA) by acquisition of control and labeled images in the same shot (fast ACTRESS) and a scan time of <1min, for the evaluation of intracranial vessels. Materials and methodsTen healthy volunteers with no unilateral symptomatic arterial stenosis, who underwent 3-tesla MRI, were investigated. Imaging parameters for the fast ACTRESS sequence were set with an acquisition time of 45s. During post-processing, the first phase in the multi-phase readout, which was defined as the control image, was subtracted from each of the other phases. Thus, four-dimensional (4D)-MRA images of each phase were obtained. The maximum intensity projection was used for the reconstruction of 4D-MRA images and time-to-signal intensity curves (TIC) obtained for each vessel. The area under the curve (AUC), peak time, and maximum signal intensity were obtained from TIC. The different labeling types were broadly divided into six groups: L1, L2, L3, L4, L5, and L6 according to the actual number of labeling pulse. ResultsA total of 5040 regions of interest were evaluated. The peak SI of L3, except for those in the A2 segment of the anterior cerebral artery, was significantly higher than that of L5. However, there were no significant differences between L4 and L5. Although the AUCs of L3 and L4 for anterior circulation were relatively higher than that of the other subgroups, the AUC of L3 was significantly higher than that of L4. ConclusionThe fast ACTRESS was optimized and indicated that the labeling type of L3 was the most appropriate for the well visualization of intracranial arteries. The fast ACTRESS sequence was useful to acquire well-delineated images of intracranial vessels in ˂1min.

Reduction of Contrast Material Volume in 3D Angiography of the Brain Using MDCT

Our aim was to investigate the image quality of MDCT angiography of the brain at a low-volume of contrast material. One hundred patients were randomly assigned to one of two groups, which differed with regard to contrast material volume and subsequent saline bolus: group A was administered 300 mg I/mL, 50 mL at an injection rate of 3.0 mL/s followed by a 20-mL saline bolus at 3.0 mL/s; group B was administered 300 mg I/mL, 100 mL at 3.0 mL/s. Of 100 total patients, 82 were analyzed: 45 in group A and 37 in group B. The attenuation and visualization of intracranial arteries were compared between the two groups. The regions of interest (ROIs) were drawn throughout the data set: internal carotid artery (ROI 1), anterior cerebral artery (ROI 2), middle cerebral artery (ROI 3), vertebral artery (ROI 4), basilar artery (ROI 5), and posterior cerebral artery (ROI 6). The differences were assessed with a Student's t test. Two readers evaluated images and graded vascular delineation of intracranial arteries by consensus. Eighty-two patients were investigated strictly according to the study protocol and were included in the per-protocol population. There were no statistically significant differences between the two groups in average attenuation (p = 0.21) and visual analysis (p = 0.84). When performing 3D angiography of the brain using 16-MDCT, the use of a 20-mL saline flush allows reduction of contrast material from 100 mL to 50 mL if all other factors are unchanged.

An autostereoscopic 3D display can improve visualization of 3D models from intracranial MR angiography

An autostereoscopic display with image quality comparable to ordinary 2D displays has recently been developed. The purpose of our study was to evaluate whether the visualization of static 3D models from intracranial time-of-flight (TOF) MR angiography (MRA) was improved by this display. Maximum Intensity Projection (MIP) and Volume Rendering (VR) 3D models of intracranial arteries were created from ten TOF MRA datasets. Thirty-one clinically relevant intracranial arterial segments were marked in the TOF source images. A total of 217 markings were used. The markings were displayed in the 3D models as overlying red dots. Three neuroradiologists viewed the static 3D models on the autostereoscopic display, with the display operating either in autostereoscopic mode or in 2D mode. The task of the neuroradiologists was to correctly identify the marked artery. A paired comparison was made between arterial identification in autostereoscopic and 2D display mode. In 314 MIP 3D models, 233 arterial markings (74%) were correctly identified with the display operating in autostereoscopic mode versus 179 (57%) in 2D mode. Odds ratio for correct identification with autostereoscopic mode versus 2D mode was 2.17 (95% confidence interval 1.55-3.04, P < 0.001). In 337 VR 3D models, 256 markings (76%) were correctly identified using autostereoscopic mode and 229 (68%) using 2D mode (odds ratio 1.49, 95% confidence interval 1.06-2.09, P = 0.021). The visualization of intracranial arteries in static 3D models from TOF MRA can be improved by the use of an autostereoscopic display.