[Novel 3D MR angiographic findings of neurovascular compressive sites in patients with trigeminal neuralgia].

Neurovascular compressive sites at the root entry zone of the trigeminal nerve were investigated in 25 patients with trigeminal neuralgia by using the fine three-dimensional (3D) magnetic resonance (MR) angiogram, obtained by a 3D time-of-flight, spoiled gradient-recalled sequence. The characteristic 3D MR angiographic findings of the offending vessels were obtained at the neurovascular compressive sites 19/23 (83%), including intermittent MR signal intensity within the vessels in 14/23 (61%), and unclear margin of the vessels in 5/23 (22%). Those abnormal 3D MR angiographic findings were commonly observed at the site of neurovascular compression in conjunction with moderate degree (grade II) and severe degree (grade III) in 19/20 (95%) of the actual nerve compression by the offending vessels. Abnormal findings with 3D MR angiograms may provide flow-related information to suggest a certain neurovascular compression upon the trigeminal nerve by the offending vessels. Those novel 3D MR angiographic findings may be useful for the diagnosis and decision-making process to execute the microvascular decompression surgery in patients with trigeminal neuralgia.

[Assessment of neurovascular compression in patients with trigeminal neuralgia with a boundary fusion three-dimensional magnetic resonance cisternogram/angiogram].

Precise assessment of the complex nerve-vessel relationship at the root entry zone (REZ) the trigeminal nerve is useful for the planning of the microvascular decompression (MVD) in patients with trigeminal neuralgia. We have applied a boundary imaging of fusion three-dimensional (3D) magnetic resonance (MR) cisternogram/angiogram. The boundary imaging allows virtual assessment of the spatial relationship of the neurovascular compression at the REZ of the trigeminal nerve. The boundary images depicted complex anatomical relationship of the offending vessels to the trigeminal nerve REZ. The presence of offending vessels, compressive site, and degree of neurovascular compression were assessed from various viewpoints in thl cistern and virtually through the brainstem and trigeminal nerve per se. The 3D visualization of the nerve-vessel relationship with fusion images was consistent with the intraoperative findings. The boundary fusion 3D MR cisternogram/angiogram may prove a useful adjunct for the diag nosis and decision-making process to execute the MVD in patients with trigeminal neuralgia.

[Fusion imaging of the 3D MR cisternography/angiography for the assessment of the intracranial major cerebral arterial stenosis].

The fusion imaging of the 3D MR cisternography (MRC) and 3D MR angiography (MRA) was applied for the assessment of the major cerebral arterial stenosis. The outer wall configurations of the stenotic lesions of the intracranial major cerebral arteries within a cisternal space were depicted by 3D MRC. Flow-related vascular structures were shown by 3D MRA. Fusion imaging was created by compositing volumetric data of MRC and co-registered MRA by using a workstation with transparent perspective volume-rendering technique. Stenotic lesions of the intracranial cerebral arteries were assessed as a discrepancy of 3D MRC and 3D MRA findings on a fusion image. Fusion imaging of 3D MRC/MRA could visualize stenotic lesions of the intracranial major cerebral arteries caused by atherosclerotic plaques; and this may provide useful information in the management of acute and chronic ischemic stroke caused by atherosclerosis of the intracranial major cerebral arteries.

[Fusion imaging of 3D MR cisternography/angiography for differential diagnosis of internal carotid-posterior communicating artery aneurysms and infundibular dilations].

By using a fusion imaging of three-dimensional (3D) magnetic resonance cisternography (MRC) and coregistered magnetic resonance angiography (MRA), protrusions at the bifurcation of the internal carotid-posterior communication artery, detected by MRA, were investigated to differentiate between the infundibular dilations and aneurysms. The MRA, obtained by the 3D time-of-flight sequence, showed the flow-related arterial structures by means of an inflow effect mainly induced by the peak systolic flow velocity. The MRC, obtained by 3D fast spin-echo sequence, depicted the contours of the vascular structures within the cisternal space in contrast to the surrounding cerebrospinal fluid. Fusion images of 3D MRC/MRA showed the anatomy of protrusions from the different viewpoints with flow-related intraluminal images (MRA) in conjunction with outer-wall configuration images of the vascular structures (MRC). This imaging technique may be useful to differentiate the infundibular dilations from the internal carotid-posterior communicating artery aneurysms.

Influence of perianeurysmal environment on the deformation and bleb formation of the unruptured cerebral aneurysm: assessment with fusion imaging of 3D MR cisternography and 3D MR angiography.

BACKGROUND AND PURPOSE: Surface irregularity and bleb formation are anatomical factors that are associated with aneurysm rupture. The perianeurysmal environment has been proposed as one factor that may influence aneurysm morphology. We have developed a fusion imaging technique of 3D MR cisternography and angiography that allows clear visualization of an aneurysm and its environment. This technique may prove useful in further understanding of the natural history of intracranial aneurysms. METHODS: Fusion images of 3D MR cisternography and angiography were reconstructed by a perspective volume-rendering algorithm from the volume datasets of MR cisternography, obtained by a T2-weighted 3D fast spin-echo sequence, and coordinated MR angiography, by a 3D time-of-flight sequence. On the fusion images, the anatomic relationship of an aneurysm to the perianeurysmal structures was assessed, and the influence of perianeurysmal environment on the deformation and bleb formation of the aneurysm was investigated. RESULTS: Marked and minor deformation and bleb formation of the aneurysmal dome were found at the areas confronted or adjacent to a certain contact with perianeurysmal structures, including cranial nerves, brain parenchyma, cranial base bones, petroclinoidal dural folds, and dura mater. CONCLUSION: Fusion images of 3D MR cisternography and angiography can depict the contact of an aneurysm with its perianeurysmal environment; this may provide an additional parameter in consideration for the natural history of cerebral aneurysms.

[Assessment of the perianeurysmal environment of unruptured internal carotid-posterior communicating artery aneurysms with fusion imaging of three-dimensional magnetic resonance cisternography and angiography].

The anatomical relationship of an unruptured internal carotid-posterior communicating artery aneurysm and the perianeurysmal environment was investigated by using three-dimensional (3D) magnetic resonance cisternography (MRC), angiography (MRA) and newly developed fusion images of 3D MRC and 3D MRA. Contact of an aneurysm with the adjacent intra- and pericisternal structures was observed in cases with the aneurysm developing and extending beyond the capacity of the surrounding subarachnoid space. Deformation and bleb formation of the aneurysmal dome was depicted at the dome in contact with the perianeurysmal environment, including the tentorial edge, the anterior petroclinoid dural fold, the oculomotor nerve, the posterior clinoid process, the dorsum sellae and the cranial base bone. By using the fusion imaging technique of 3D MRC and 3D MRA, assessment of the contact of an unruptured cerebral aneurysm with its perianeurysmal environment can be made. Such contact gives ride to risk of deformation and bleb formation of the aneurysmal dome; and may result in cranial nerve symptoms and accelerate rupture from an unruptured cerebral aneurysm.

[Assessment of the signal intensity distribution pattern within the unruptured cerebral aneurysms using color-coded 3D MR angiography].

To evaluate the interaction between the MR signal intensity distribution pattern and bleb formation/ deformation of the aneurysmal dome, fifty cases of the unruptured cerebral aneurysms were investigated with the color-coded 3D MR angiography. Patterns were categorized into central-type, neck-type and peripheral-type according to the distribution of MR signals with low-, moderate- and high signal intensity areas. Imaging analysis revealed the significant relationship (P < 0.02) of the peripheral-type aneurysms to the bleb formation and deformation of the dome, compared with those of central- and neck-type. Additionally, peripheral-type signal intensity distribution pattern was shown with aneurysms harboring relatively large dome size and lateral-type growth including internal carotid aneurysms. Prospective analysis of intraaneurysmal flow pattern with the color-coded 3D MR angiography may provide patient-specific analysis of intraaneurysmal flow status in relation to the morphological change of the corresponding aneurysmal dome in the management of unruptured cerebral aneurysms.

Visualization of aneurysmal contours and perianeurysmal environment with conventional and transparent 3D MR cisternography.

We have developed conventional and transparent 3D MR cisternography to investigate the spatial relationship between the contours of aneurysmal complex and the perianeurysmal structures including the cranial nerves, dural fold, cranial base bone, and brain parenchyma. Volume data obtained by a T2-weighted 3D fast spin-echo sequence were reconstructed by using a perspective volume-rendering algorithm with a transluminal imaging technique. 3D MR cisternograms provide useful anatomic information in the therapeutic and follow-up management of unruptured cerebral aneurysms.