Fusion imaging of three-dimensional magnetic resonance cisternograms and angiograms for the assessment of microvascular decompression in patients with hemifacial spasms

OBJECT: The precise preoperative assessment of the complex nerve-vessel relationship at the root exit zone (RExZ) of the facial nerve is important when planning microvascular decompression (MVD) in patients with hemifacial spasms. The authors have developed an imaging technique-the fusion of 3D magnetic resonance (MR) cistemography and coregistered 3D MR angiography images-that allows clear visualization of the spatial relationship between the vessels and the rootlet of the facial nerve at the brainstem. METHODS: The authors reconstructed 3D MR cisternograms and 3D MR angiograms by using a perspective volume-rendering algorithm that they applied to the volumetric data sets of the following modalities: MR cisternography (a T,-weighted 3D fast spin echo sequence) and coregistered MR angiography (a 3D time-of-flight sequence). The complex anatomical relationship between the offending vessels and the facial nerve RExZ was inspected preoperatively by examining the fusion images from various perspectives within the cerebellopontine angle cistern, within the affected facial nerve, and through the simulated surgical route. The reconstructed 3D findings of the nerve-vessel relationship were compared with the intraoperative findings. Postoperatively, the fused 3D MR imaging technique was used to confirm that microsurgical dissection and the interposed prosthesis had succeeded in maintaining the causative vessels in a position away from the RExZ. CONCLUSIONS: The fusion of 3D MR cisternograms and 3D MR angiograms may prove useful in the pre- and postoperative assessment of MVD in patients with hemifacial spasm.     

Characterization of the volume data of three-dimensional CT and MR angiograms for the delineation of cerebral aneurysms

Three-dimensional CT angiography and MR angiography with perspective volume rendering were used to investigate two patients with cerebral aneurysms. Compared with the intraoperative photographs, volume data from CT angiogram and MR angiogram were characterized on simulated virtual 3D images with virtual neuro-endoscopic and transluminal imaging techniques. In a case of an unruptured double internal carotid (C2) blister aneurysm, CT angiogram showed a configuration of the distal aneurysm similar to that in the intraoperative photograph, but failed to show the margin of the proximal aneurysm adjacent to the anterior clinoid process bone due to a partial volume effect. The MR angiogram represented both aneurysms and the parent artery, including the C3-C2 internal carotid artery. The whole shape of the aneurysm, however, differed from that in the intraoperative photograph, showing instead an elongation of the aneurysmal dome. In a case of a ruptured tiny middle cerebral artery aneurysm, CT angiogram failed to show the subtle bulging of the aneurysm. In contrast, MR angiogram clearly demonstrated the bulging of the walls at the beginning of the ascending and descending branches of the M2, which is consistent with the aneurysmal convolution observed in the intraoperative photograph. In both cases, transluminal images of the 3D-CT and MR angiograms represented the intraluminal contour of the vessel and aneurysmal walls as a series of rings, and allowed a transluminal view from outside the vessel lumen through the spaces between the rings of the vessel wall. The orifices of the aneurysm and parent arteries were shown through the vessel and aneurysmal walls, providing an extensive perspective view of the angio-architecture of the aneurysm. Morphological configuration of the inner space of the vessel and aneurysm was well visualized on CT angiogram, which was consistent with the operative view. Due to a partial volume effect, the surrounding bony and venous structures overlapped with the aneurysm made them indistinguishable from each other. In contrast, the MR angiogram provided the flow-related volume information, so that dynamics of the flow in the vessel lumen visualized the elongation of the aneurysmal dome and subtle bulging of the tiny aneurysm.     

Children with cerebral venous thrombosis diagnosed with magnetic resonance imaging and magnetic resonance angiography.

From 1985 to 1991, 13 children were diagnosed at the University of Illinois College of Medicine at Peoria, Saint Francis Medical Center, with cerebral venous thrombosis (CVT) by magnetic resonance imaging scan. Ages ranged from newborn to 5 years. Six children were premature neonates, five were term neonates and two were 5 years old. In the premature neonates, thrombosis was usually associated with other problems. All the term neonates had seizures. In all neonates, thrombosis resolved without any specific treatment. In the two older children, one presented with pseudotumor cerebri and one with coma. These children required neurosurgical intervention. Follow-up magnetic resonance imaging scans were obtained in 9 of 13 children and showed thrombus resolution in each case. Three children were studied in the acute and convalescent stages by magnetic resonance angiography using time-of-flight techniques. Each follow-up magnetic resonance angiogram showed improvement in venous flow consistent with their clinical course and other imaging studies. We conclude that 1) CVT in children encompasses a range of clinical conditions which may or may not require neurosurgical intervention; 2) magnetic resonance imaging is superior to other modalities for the diagnosis of CVT; and 3) magnetic resonance angiography is an alternative means to monitor the evolution of CVT and efficacy of therapeutic intervention.     

Evaluation of hyperacute cerebral ischemic lesions with transparent 3D visualization of echo-planar diffusion-weighted magnetic resonance imaging

Transparent three-dimensional (3D) visualization of hyperacute cerebral ischemic lesions was reconstructed using parallel volume-rendering algorithm by selecting the high signal intensity area for ischemic lesion and the low signal intensity area for parenchymal margin, respectively, from the volume dataset of echo-planar diffusion-weighted magnetic resonance imaging (DWI). The 3D DWI can depict the ischemic lesions at the hyperacute stage of cerebral ischemia, transparently through the contours of brain and ventricular structures. Application of 3D DWI and evaluation of ischemic lesions were discussed in three cases of hyperacute cerebral infarction.     

Evaluation of the contours and perianeurysmal environment of unruptured cerebral aneurysms, using three-dimensional magnetic resonance cisternogram

To evaluate the anatomical relationship between cerebral aneurysm and the perianeurysmal environment within a cisternal space, the contours of an unruptured cerebral aneurysm and pericisternal structures were depicted on a three-dimensional (3D) MR cisternogram. By using perspective volume-rendering algorithm, the 3D MR cisternograms were reconstructed from the source axial volume data set obtained by the T2-weighted 3D fast spin-echo sequence. Those images were shown together with the coordinated 3D MR angiograms through similar visual projections, and then compared with the intraoperative findings. The outer wall configurations of cerebral aneurysms within the cisternal space were shown in conjunction with the accompanying surface veins, adjacent cranial nerves, dura mater and tentorial edge, cranial base bone, and surrounding pericisternal brain surfaces. With application of 3D MR cisternograms in the management of unruptured cerebral aneurysm, the anatomical relationship between the aneurysmal contours and the perianeurysmal environment could be evaluated the within the cisternal space. This might provide another clinical factor when considering the potential risk of growth, rupture, and symptomatic cranial nerve signs of an unruptured cerebral aneurysm.     

Isolated cerebral varix with magnetic resonance imaging findings--case report.

A rare case of isolated cerebral varix of the left deep sylvian vein was discovered incidentally in an 11-year-old boy by computed tomographic scanning, magnetic resonance (MR) imaging, and cerebral angiography. MR imaging was most useful in diagnosis of cerebral varix. Review of 21 similar reported cases shows no significant in age, sex, location, or size character.     

Evaluation of the femoral midshaft in children with cerebral palsy using magnetic resonance imaging

Summary  Magnetic resonance imaging was used to show that children with quadriplegic cerebral palsy and unable to ambulate independently compared to typically developing children have a remarkably underdeveloped femoral midshaft as indicated by a very thin diameter, a very thin cortical wall, and very low strength estimates. Introduction  The femoral shaft is very susceptible to fracture in children with quadriplegic cerebral palsy (QCP); however, its structure and strength have not been evaluated. Methods  The volume and width of the middle third of the femur (midfemur) and its cortical wall and medullary cavity were assessed in children with QCP and unable to ambulate independently and typically developing children (n = 10/group) using magnetic resonance imaging (MRI). Estimates of cross-sectional moment of inertia (CSMI), section modulus (Z), and polar moment of inertia (J) were also determined. Results  Total volume of the midfemur and volume of its cortical wall and medullary cavity were substantially lower in children with QCP than controls (51–55%; p < 0.001). In addition, the total midfemur, its medullary cavity and the anterior, posterior, and lateral sections of its cortical wall were thinner (27–43%) in children with QCP (p < 0.001). The midfemur in children with QCP also had remarkably lower CSMI, Z, and J (60–71%; p < 0.001). Conclusions  Children with QCP who lack the ability to ambulate independently have midfemurs that are very thin with very thin cortical walls and very low estimated strength. The disparity can be detected using MRI.     

Evaluation of live renal donors with three-dimensional contrast-enhanced magnetic resonance angiography in comparison to catheter angiography

BACKGROUND: Catheter angiography is traditionally used to determine renal arterial anatomy in live renal donors. Three-dimensional (3D) contrast-enhanced magnetic resonance imaging (MRA) has been suggested as a noninvasive replacement. We assessed the possibility of using MRA in live renal donors in Malaysia. METHODS: Twenty-six consecutive live renal donors were recruited from 2000 to 2002. All potential donors underwent evaluation of the renal arteries using both techniques. Angiographic findings from both modalities were subsequently compared with surgical findings at the time of donor nephrectomy. The total number and diameter of the arteries and the presence of early branching and renal abnormalities were noted. RESULTS: Both angiographic modalities were able to detect multiple renal arteries with catheter angiography having a sensitivity of 100% and MRA a sensitivity of 97%. MRA missed one 1-mm artery due to a low index of suspicion. Renal artery caliber measurements were not significantly different between the two methods. However, both techniques tended to overestimate the caliber of the renal arteries when compared with measurements taken at surgery. Early branching was found in two arteries at the time of surgery, but only one was detected by both techniques. Renal cysts seen on MR were not detected by catheter angiography. CONCLUSIONS: Our findings suggest that noninvasive MRA is a promising substitute for catheter angiography to evaluate the renal arteries of live donors.     

Results of nuclear magnetic resonance with cerebral glioma. Comparison with computed tomography

Our experience using nuclear magnetic resonance (NMR) in eight patients with abnormalities on computed tomography (CT) scans suggesting glioma is reported. Three patients underwent biopsies. Two patients had grade II astrocytomas. Difficulty was encountered confirming the diagnosis of astrocytoma on frozen sections in one patient, and permanent sections were required for diagnosis in the other. The third patient to undergo biopsy had a grade III anaplastic mixed glioma. Biopsy of subsequent patients with probable gliomas was not done because of the risk of producing neurological deficit. The NMR images suggest that lower-grade astrocytomas are well circumscribed, whereas higher-grade gliomas affect adjacent association bundles by direct extension of tumor cells or vasogenic edema.     

Bladder function in elderly men with subclinical brain magnetic resonance imaging lesions.

Among 43 men more than 60 years old who complained of urinary irritative symptoms 40 had subclinical lesions in the brain on magnetic resonance imaging (MRI). Of these 40 patients 23 (57.5%) had detrusor hyperreflexia. The mean age of the patients with and without detrusor hyperreflexia was 75.8 and 68.2 years, respectively, which is a statistically significant difference. Patients with detrusor hyperreflexia were more likely to have lesions of the basal ganglia than patients without detrusor hyperreflexia. This study suggests that detrusor hyperreflexia, subclinical MRI lesions in the brain and aging are intimately interrelated.     

Spinal leptomeningeal metastasis from cerebral glioblastoma. Appearance on magnetic resonance imaging.

A case of circumferential leptomeningeal metastasis to the spinal cord from an intracranial glioblastoma multiforme (spinal meningeal gliomatosis) is presented. The clinical, radiographic, and pathological features are described. Spinal magnetic resonance imaging with gadolinium-diethylenetriaminepentaacetic acid accurately demonstrated the spread of disease when compared with autopsy findings. The value of spinal magnetic resonance imaging in patients with symptoms attributable to cerebrospinal fluid metastases is discussed.     

Rosai-Dorfman disease presenting multiple intracranial lesions with unique findings on magnetic resonance imaging. Case report.

Rosai-Dorfman disease (RDD) is a rare idiopathic histoproliferative disease affecting the systemic lymph nodes. Although an extranodal lesion has also been recognized, central nervous system involvement is extremely rare. To the authors' knowledge, only 20 cases of intracranial lesions have been reported previously. Intracranial RDD is clinically and radiologically difficult to distinguish from meningioma, and histological examination is essential for a definitive diagnosis. The authors treated a large frontal lobe tumor associated with multiple meningeal nodules in a 67-year-old patient presenting with diplopia and headache. Radiological examination indicated that the mass was an inflammatory lesion rather than a meningioma. Microscopically the lesion consisted of mixed inflammatory infiltrate with marked emperipolesis, which is characteristic of RDD. A review of the literature and a discussion of the differential diagnosis of this rare lesion are also presented.     

Multiple cerebral hydatid disease: case report with magnetic resonance imaging study.

A case of multiple hydatid cysts of the brain is reported. Computed tomographic and magnetic resonance imaging scanning revealed a thick and calcified pericystium. These findings allowed appropriate surgical planning, with a marked recovery of the neurological deficits and absence of relapse in the follow-up period.     

Delineating gray and white matter involvement in brain lesions: three-dimensional alignment of functional magnetic resonance and diffusion-tensor imaging

OBJECT: The role of functional magnetic resonance (fMR) imaging has become increasingly important in the presurgical mapping of gray matter. Neurosurgical interventions often involve fiber bundles that connect critical functional areas. Recently, diffusion-tensor (DT) imaging has enabled the visualization of fiber bundle direction and integrity, thus providing the ability to delineate clearly white matter from gray matter tissue. The main objective of this study was to improve the presurgical assessment of critical functionality in the vicinity of brain lesions by combining DT and fMR imaging methodologies. METHODS: Twenty patients with various space-occupying brain lesions underwent imaging for presurgical evaluation of motor and/or somatosensory functions. The authors focus on five patients with diverse space-occupying brain lesions. Diffusion tensor-based fiber tracking and fMR imaging activation maps were superimposed in three dimensions to visualize pyramidal tracts corresponding to motor and somatosensory regional activation. CONCLUSIONS: The combination of DT and fMR imaging for presurgical functional brain mapping provides valuable information that cannot be extracted using either method alone. The validity and sensitivity of noninvasive functional mapping for surgical guidance could be improved by considering results obtained with both methods. Furthermore, the use of three-dimensional visualization seems crucial and unique for viewing and understanding the complicated spatial relationship among the lesion, gray matter activation, and white matter fiber bundles.     

Bypass surgery in patients with intracranial stenotic lesions. Postoperative morbidity and angiographic findings

Postoperative morbidity in patients with intracranial stenotic lesions following extracranial-intracranial arterial (EC-IC) bypass is not well defined. A high rate of neurological complications associated with occlusion of the stenotic arteries after surgery has recently been reported. In the period June, 1976, to March, 1984, the authors performed EC-IC bypass procedures in 19 patients with intracranial stenotic arteries. Most of the patients were initially treated pharmacologically (usually by anticoagulant therapy). Surgery was performed if the symptoms recurred while the patients were under pharmacological treatment and if angiography confirmed arterial stenosis. Antiplatelet therapy was given until the day of surgery and during the entire follow-up period. No permanent postoperative morbidity was observed in the series. One patient, with stenosis of the left siphon, the A1 segment of the anterior cerebral artery, and the M1 segment of the middle cerebral artery, had a transient dysphasia and right hemiparesis (lasting 3 days) in the presence of an unchanged arterial stenosis. In five patients early postoperative angiography (at 5 to 21 days) revealed occlusion of previously stenotic arteries. In one patient the occlusion was disclosed only on a later angiographic study, 2 months after surgery. Although EC-IC bypass is generally not a very high-risk operation in patients with intracranial arterial stenosis, there is a high percentage of immediate postoperative occlusion, and the authors suggest caution in determining indication for surgical treatment.