Showing papers in "American Journal of Neuroradiology in 1996"

Clinical applications of proton MR spectroscopy

Abstract: Magnetic resonance (MR) spectroscopy has received little attention from the clinical radiology community. Indeed, most MR spectroscopic studies are performed by a small and dedicated group of individuals, mostly basic scientists. This behavior is partly because MR spectroscopy does not produce “pictures” but results in “graphs,” and until lately, it could only be obtained with dedicated units and software. At present, MR spectroscopy may be obtained with many clinical 1.5-T MR units and commercially available software. Adequate MR spectra may be obtained in periods of time as short as 10 to 15 minutes. Therefore, they may be added to routine MR imaging studies without significant time penalties. Moreover, MR spectroscopy provides greater information concerning tissue characterization than what is possible with MR imaging studies alone. This article will review the current status of proton MR spectroscopy with emphasis on its clinical utility for evaluation of neurologic disorders. Also, we include a section on some innovative and promising uses of proton MR spectroscopy. The information provided here is simplified in the hope that its understanding will lead to increased use of proton MR spectroscopy by clinical radiologists.

The spectrum of brain MR abnormalities in sickle-cell disease: a report from the Cooperative Study of Sickle Cell Disease

Abstract: PURPOSE To define the spectrum of abnormalities in sickle-cell disease, including infarction, atrophy, and hemorrhage, that are identified by brain MR imaging. METHODS All MR studies included T1, T2, and intermediate pulse sequences. Images were interpreted without knowledge of the clinical history or neurologic examination findings. Brain MR imaging was performed in 312 children with sickle-cell disease. RESULTS Seventy patients (22%) had infarction/ischemia and/or atrophy, infarction/ischemia was noted in 39 children (13%) who had no history of a stroke (the "silent" group). The prevalence rates for silent lesions were 17% for sickle-cell anemia and 3% for hemoglobin sickle-cell disease. For patients with sickle-cell anemia and a history of cerebrovascular accident, infarction/ischemia lesions typically involved both cortex and deep white matter, while silent lesions usually were confined to deep white matter. Within the age range studied, the prevalence of infarction/ischemia did not increase significantly with age, although older patients with lesions had more lesions than did younger patients with lesions. CONCLUSIONS Brain MR imaging showed infarction/ischemia in the absence of a recognized cerebrovascular accident in 13% of patients. The prevalence of these lesions did not increase significantly between the ages of 6 and 14 years, suggesting that lesions are present by age 6. However, the increase in the average number of lesions per patient with age may indicate progressive brain injury.

Prognostic value of the hyperdense middle cerebral artery sign and stroke scale score before ultraearly thrombolytic therapy.

Abstract: PURPOSE To determine the relationship between the hyperdense middle cerebral artery sign (HMCAS) and neurologic deficit, as evidenced by the National Institutes of Health (NIH) stroke scale score, and to determine the relationship of the HMCAS and the NIH stroke scale score to arteriographic findings after thrombolytic therapy. METHODS Fifty-five patients with acute ischemic stroke were rated on the NIH stroke scale, were examined with CT, and were treated with intravenous alteplase within 90 minutes of symptom onset. Presence of the HMCAS was determined on the baseline CT scan by a neuroradiologist blinded to the patient9s neurologic deficit. Patients with the HMCAS were compared with those without HMCAS with regard to baseline NIH stroke scale score, 2-hour NIH stroke scale score, findings at posttreatment arteriography, 3-month residual neurologic deficit, and 3-month ischemia volumes as evidenced on CT scans. RESULTS Eighteen patients (33%) had the HMCAS. These patients had a median baseline NIH stroke scale score of 19.5 compared with a median score of 10 for the patients lacking the HMCAS sign. At 3 months, one (6%) of the HMCAS-positive patients was completely improved neurologically compared with 17 (47%) of the HMCAS-negative patients. Restricting analysis to those patients with a stroke scale score of 10 or greater (n = 37), 18 HMCAS-positive patients showed less early neurologic improvement, were less likely to be completely improved at 3 months, and had larger infarcts compared with the 19 HMCAS-negative patients. Compared with the HMCAS-positive and HMCAS-negative patients with a stroke scale score of 10 or greater, patients with a stroke scale score of less than 10 had fewer occlusive changes of the internal carotid and middle cerebral arteries on posttreatment arteriograms and had a better neurologic recovery at 3 months. CONCLUSION The presence of the HMCAS on CT scans obtained within 90 minutes of stroke onset is associated with a major neurologic deficit, and in this study it predicted a poor clinical and radiologic outcome after intravenous thrombolytic therapy. However, a major neurologic deficit, defined as a stroke scale score of 10 or more, was better than a positive HMCAS as a predictor of poor neurologic outcome after thrombolytic therapy. Patients with a low stroke scale score (

MR of cerebral abnormalities concomitant with primary intracerebral hematomas.

Abstract: PURPOSE To determine whether arteriolar vessel wall degeneration in primary intracerebral hematomas might be associated with ischemic brain lesions and clinically silent (apparently intracerebral) previous hemorrhages. METHODS The MR images of 120 consecutive patients (mean age, 60 years; age range, 22 to 84 years) with their first stroke caused by a primary intracerebral hematoma were reviewed retrospectively for coexisting ischemic damage and previous bleeds. RESULTS Early confluent to confluent white matter hyperintensities, lacunes, or infarction were present in 83 (69%) of the patients, and 39 (33%) had had previous hemorrhages consisting of microbleeds or old hematomas. Extensive white matter hyperintensities and lacunes were most frequent in patients with thalamic primary intracerebral hematomas. There was no relationship between the frequency of old hemorrhages and the location of subsequent primary intracerebral hematomas. CONCLUSION Clinically silent ischemic lesions and previous hemorrhages are a common finding on MR images of patients with primary intracerebral hematoma. They may therefore serve as evidence of diffuse microangiopathy with a possible increased risk for cerebral hemorrhage.

Endovascular therapy for the carotid blowout syndrome in head and neck surgical patients: diagnostic and managerial considerations.

Abstract: PURPOSE To review our institution9s recent experience with patients with carotid blowout syndrome who were referred for emergency diagnostic angiography and endovascular therapy. METHODS Eighteen consecutive patients who had had surgery for cancer of the head and neck and in whom carotid blowout syndrome had occurred were referred to our service in accordance with a standardized protocol. RESULTS Twenty-three angiographic pathoetiologic conditions were diagnosed in the 18 patients; the majority of these were pseudoaneurysms involving various segments of the carotid system. Multiple lesions were detected in five patients. Most patients were treated by means of permanent balloon occlusion; in 8 patients with either multiple lesions or impending rupture requiring flap reconstruction, a composite permanent balloon occlusion of the affected carotid system was performed. Hyperacute hemorrhages were arrested in all cases. Hemorrhages reoccurred in 2 cases, and in 2 patients who had permanent balloon occlusion of the internal carotid artery, transient ischemic attacks occurred, which appeared to be related to temporary collateral reserve failure. No permanent neurologic complications ensued. CONCLUSION Our recent experience with carotid blowout syndrome suggests that this clinical diagnosis represents a heterogeneous group of angiographic pathoetiologies that the physician should evaluate carefully before proceeding with endovascular therapy. Specific endovascular approaches depend on the pathoetiologic mechanism of active or impending hemorrhage and the urgency with which intervention is required.

Interobserver agreement in assessing early CT signs of middle cerebral artery infarction.

Abstract: PURPOSE To assess the reliability of detecting signs of hemispheric infarction on CT scans obtained within 6 hours of the onset of symptoms. METHODS A neuroradiologist selected 12 normal and 33 abnormal CT studies showing the hyperdense middle cerebral artery sign (HMCAS) (n = 10), brain swelling (n = 22), and parenchymal hypodensity (n = 33) from two series of 750 patients with recent onset of middle cerebral artery stroke. These selections served as the reference source for a nonblinded analysis of the initial and follow-up CT scans. Six neuroradiologists then reviewed the CT scans twice, first blinded then not blinded to clinical symptoms. They assessed the signs of infarction for each hemisphere separately and estimated the volume of abnormal parenchymal hypodensity in increments of 20% within the territory of the middle cerebral artery. RESULTS Unblinding the reviewers did not change interobserver agreement significantly. The chance adjusted agreement was moderate to substantial: kappa = .62 (95% confidence interval [CI], .46 to .78) and kappa = .57 (95% CI, .33 to .81) for the HMCAS of the right and left hemisphere, respectively; kappa = .59 (95% CI, .47 to .71) and kappa = .56 (95% CI, .38 to .74) for focal brain swelling of the right and left hemisphere, respectively; and kappa = .58 (95% CI, .50 to .66) and kappa = .55 (95% CI, .32 to .67) for parenchymal hypodensity of the right and left hemisphere, respectively. Weighted kappa was .65 and .57 for the estimation of the hypodense tissue volume in the right and left hemisphere, respectively. Agreement with the reference source ranged from 73% to 93% for all variables and both hemispheres. CONCLUSION Even with no clinical information, neuroradiologists can assess subtle CT signs of cerebral infarction within the first 6 hours of symptom onset with moderate to substantial interobserver agreement.

Chorea-Ballismus with Nonketotic Hyperglycemia in Primary Diabetes Mellitus

Abstract: PURPOSE To describe the neuroimaging (Ct, MR, and single-photon emission CT [SPECT]) findings in a series of patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus and to correlate the imaging findings with the clinical presentation. METHODS The neuroimaging and clinical data from 10 patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus were evaluated. Family and drug histories, as well as other causes of chorea, were excluded. All 10 patients had CT, 5 also had MR imaging, and 3 had SPECT examinations. Three had follow-up CT and MR imaging studies, and MR findings were correlated with CT findings in 5 cases. Two experienced neuroradiologists, aware of the diagnosis but blinded to the clinical status of the patients, evaluated all images and reached a consensus as to the final interpretation. RESULTS CT studies in 9 of 10 patients showed a hyperdense putamen and/or caudate nucleus; in 1, the CT findings were normal. T1-weighted MR images in all 5 patients who had MR imaging (including the patient with a normal CT study) showed hyperintense lesions without significant T2 signal alternation at the basal ganglia. In all 3 of the patients who had SPECT studies of the brain, the scans revealed hypoperfusion at corresponding areas. All 3 follow-up studies depicted resolution of the lesions in the abnormal basal ganglia. Increased hypointensity on T2-weighted and gradient-echo T2*-weighted images was also observed in the sequential MR images. In all patients, the initial side of involvement correlated well with the neuroimaging findings. The chorea resolved within 2 days after treatment of the hyperglycemia in 9 patients. CONCLUSION In patients with chorea-ballismus associated with nonketotic hyperglycemia in primary diabetes mellitus, CT and T1-weighted MR images show unilateral or bilateral lesions of the putamen and/or caudate. SPECT scans show hypoperfusion. These findings may be related to petechial hemorrhage and/or myelin destruction. Early recognition of these imaging characteristics may facilitate diagnosis of primary diabetes mellitus with hyperglycemia and prompt appropriate therapy.

Trisacryl gelatin microspheres for therapeutic embolization, I: development and in vitro evaluation.

Abstract: PURPOSE To develop a precisely calibrated, perfectly spherical, stainable, soft, and implantable but nonresorbable particulate embolization material. METHODS Calibrated particles with a trisacryl gelatin polymer core and hydrophilic surface characteristics were obtained by reversed emulsion synthesis followed by application of a wet-sieving technique. Particles were suspended in saline, bottled, and sterilized. Quality control included analysis of particle diameters before and after sieving and of suspension sterility and apyrogenicity. Particles were subsequently tested to ascertain their compatibility with commercially available microcatheters. RESULTS The resulting embolization material consisted of spherical, stainable microspheres of medical grade with diameters ranging from 130 microns to 1200 microns. Sieving the suspension produced particle groups of homogeneous size (accuracy, +/- 20-100 microns). At injection, the particles showed no tendency to build aggregates or to obstruct the microcatheters. CONCLUSION Precisely calibrated and easy-to-use microspheres were obtained that satisfied the biomedical requirements for implantation as an embolization material.

Posttraumatic Olfactory Dysfunction: MR and Clinical Evaluation

Abstract: PURPOSE To evaluate the sites of injury in patients with posttraumatic olfactory deficits and to compare damage with findings on clinical olfactory tests. METHODS Twenty-five patients with posttraumatic olfactory dysfunction were examined by means of olfactory testing, endoscopy, and MR imaging. MR surface-coil scans through the olfactory bulbs and tracts and head-coil scans of the temporal lobes were evaluated. Quantitative and qualitative gradings of damage to the olfactory bulbs, tracts, subfrontal region, hippocampus, and temporal lobes were compared with results on tests of odor identification, detection, memory, and discrimination. RESULTS Twelve patients were anosmic, eight had severe impairment, and five were mildly impaired. Injuries to the olfactory bulbs and tracts (88% of patients), subfrontal region (60%), and temporal lobes (32%) were found, but these did not correlate well with individual olfactory test scores. Volumetric analysis showed that patients without smell function had greater volume loss in olfactory bulbs and tracts than did those posttraumatic patients who retained some sense of smell. Qualitative and quantitative assessments of damage showed few significant correlations with olfactory tests, probably because of multifocal injuries, primary olfactory nerve damage, and the constraints of a small sample size on the detection of clinically significant differences. CONCLUSION MR imaging shows abnormalities in patients with posttraumatic olfactory dysfunction at a very high rate (88%), predominantly in the olfactory bulbs and tracts and the inferior frontal lobes.

Relationship of the optic nerve to the posterior paranasal sinuses: a CT anatomic study.

Abstract: PURPOSE To delineate the relationship between the optic nerves and the posterior paranasal sinuses using CT data. METHODS Direct coronal sinus CT scans of 150 consecutive patients with chronic inflammatory sinus disease were reviewed by two radiologists. Axial oblique reconstructions along the course of the optic nerve were obtained for the first 100 patients. The direct relationship between the optic nerve and the posterior ethmoid and sphenoidal sinuses was recorded, as were identations into the sinus wall, course of the nerve through the sinus region, pneumatization of the anterior clinoid process, and bone dehiscence. RESULTS The relationship of the optic nerve to the posterior paranasal sinus fell into one of four discrete categories, type 1 through type 4. All 300 nerves were intimately related to the sphenoidal sinus. A small minority (3%) were in contact with the posterior ethmoidal sinus. Only type 4 nerves had contact with the posterior ethmoid air cell. Type 1 nerves course adjacent to the sphenoid sinus without indentation of the wall (228 nerves, 76%). Type 2 nerves course adjacent to the sphenoidal sinus, causing indentation of the sinus wall (44 nerves, 15%). Type 3 nerves course through the sphenoid sinus (19 nerves, 6%). Type 4 nerves course immediately adjacent to the sphenoidal sinus and the posterior ethmoidal air cell (9 nerves, 3%). Bone dehiscence over the optic nerve was found in 24% of the nerves; 4% of the optic nerves in our study had an associated pneumatized anterior clinoid process and 77% of these had an associated dehiscence over the optic canal. CONCLUSIONS In all our cases the course of the optic nerve was adjacent to the sphenoidal sinus. Only 3% were in contact with the posterior ethmoidal sinus. Anatomic configurations that predispose the optic nerve to injury include type 2 or 3 optic nerves, bone dehiscence over the nerve, and pneumatization of the anterior clinoid process. These configurations are common and should be routinely sought out so that devastating complications from sinus surgery can be avoided.

Noninvasive evaluation of malignancy of brain tumors with proton MR spectroscopy.

Abstract: PURPOSE To test clinical proton MR spectroscopy as a noninvasive method for predicting tumor malignancy. METHODS Water-suppressed single-voxel point resolved spectroscopy in the frontal white matter of 17 healthy volunteers and 25 patients with brain tumors yielded spectra with peaks of N-acetyl aspartate (NAA), choline-containing compounds (Cho), creatine/phosphocreatine (Cre), and lactate. These peak intensities were semiquantitated as a ratio to that of the external reference. The validity of the semiquantitation was first evaluated through phantom and volunteer experiments. RESULTS The variation in measurements of the designated region in the volunteers was less than 10%. Normal ranges of NAA/reference, Cho/reference, and Cre/reference were 3.59 +/- 0.68, 1.96 +/- 0.66, and 1.53 +/- 0.64 (mean +/- SD), respectively. In 17 gliomas, the Cho/reference value in high-grade gliomas was significantly higher than in low-grade gliomas. Levels of NAA/reference were also significantly different in low-grade and high-grade malignancy. In eight meningiomas (four newly diagnosed and four recurrent), the level of Cho/reference was significantly higher in recurrent meningiomas than in normal white matter or in newly diagnosed meningiomas. CONCLUSIONS Higher grades of brain tumors in this study were associated with higher Cho/reference and lower NAA/reference values. These results suggest that clinical proton MR spectroscopy may help predict tumor malignancy.

Intracranial hemangiopericytomas: MR and CT features.

Abstract: PURPOSE To describe the MR and CT imaging features of hemangiopericytoma and to identify the characteristics that might distinguish them from meningioma. METHODS We retrospectively reviewed the CT and MR findings in 34 pathologically proved cases of hemangiopericytoma. We evaluated the size, shape, and location of the tumor; the presence of hydrocephalus, edema, and mass effect; the type of dural attachment (broad-based or narrow-based) and bone changes (erosion, hyperostosis); and the tumor9s density, signal, and contrast-enhancement characteristics. RESULTS Thirty of 34 tumors were 4 cm or more in greatest dimension, 32 were lobular, and only seven were in the posterior fossa. Hydrocephalus was present in 18, edema in 30, and mass effect in 33. Twenty-three had broad-based dural attachment and 11 had narrow-based attachment. All 26 unenhanced CT scans showed hyperdense tumors; 19 were heterogeneous and seven homogeneous. All 27 contrast-enhanced CT scans showed enhancement; 17 were heterogeneous and 10 homogeneous. Bone erosion was present in 17 of 29 hemangiopericytomas imaged with CT. None had hyperostosis or tumor calcifications. On T1-weighted MR images, 13 of 17 tumors were isointense with cortical gray matter; on T2-weighted image, 10 of 17 were isointense. All 14 tumors imaged with contrast enhanced T1-weighted MR imaging showed enhancement, and 13 of these were heterogeneous; eight of the 14 had a "dural tail" sign. CONCLUSION Intracranial hemangiopericytomas are multilobulated, extraaxial tumors, sometimes associated with narrow-based dural attachment and bone erosion. Unlike with meningiomas, hyperostosis and intratumoral calcification are not present.

MR Evaluation of Developmental Venous Anomalies: Medullary Venous Anatomy of Venous Angiomas

Abstract: PURPOSE To present characteristic MR findings of developmental venous anomalies (DVAs) in terms of location of caput and draining veins, to correlate these findings with normal medullary venous anatomy, and to suggest an approach to the evaluation of DVAs by means of MR imaging. METHODS We reviewed the contrast-enhanced MR examinations of 61 patients with DVA, which were selected from 4624 consecutive cranial MR examinations. Site of the DVA and size and direction of draining veins were recorded. RESULTS Seventy-two DVAs with 78 draining veins were located: 18 were juxtacortical, 13 were subcortical, and 41 were periventricular or deep. Twenty-six of the DVA caputs were frontal, 16 were parietal, 13 were in the brachium pontis/dentate, seven were in the temporal lobe, three were in the cerebellar hemisphere, three were in the occipital lobe, three were in the basal ganglia, and one was in the pons. The draining veins were superficial in 29 cases and deep in 49. Of the 36 supratentorial deep draining veins, 16 were in the trigone/occipital horn, 11 were in the mid-body of the lateral ventricle, seven were in the frontal horn, and two were in the temporal horn. Among the 14 infratentorial deep draining veins, five were in the lateral recess of the fourth ventricle, four were anterior transpontine veins, three were lateral transpontine veins, and two were precentral cerebellar veins. CONCLUSION The DVA caputs and their draining veins occurred in typical locations that could be predicted from the normal medullary venous anatomy, with the frontal, parietal, and brachium pontis/dentate being the most common locations. Drainage can occur in superficial cortical veins or sinuses or in deep ventricular veins or in both, no matter where the caput is located. Whether drainage was superficial or deep could not be predicted on the basis of the site of the DVA caput. Contrast-enhanced T1-weighted MR images showed the DVAs best, but diagnosis could be made from T2-weighted MR images.

Trisacryl gelatin microspheres for therapeutic embolization, II: preliminary clinical evaluation in tumors and arteriovenous malformations.

Abstract: PURPOSE To evaluate an embolic agent that is precisely calibrated, perfectly spherical in shape, and soft but nonresorbable for use in the embolization of vascular disease of the head, neck, and spine in humans. METHODS We used supple, hydrophilic, and calibrated trisacryl gelatin microspheres 200, 400, 600, 800 and 1000 microns in diameter for superselective embolization in 105 patients (27 tumors, 14 facial arteriovenous malformations [AVMs], 37 spinal cord AVMs, 21 cerebral AVMs, and 6 miscellaneous diseases). We used particles in 200 to 600 microns in diameter for tumors and for facial AVMs, particles 400 to 600 microns in diameter for spinal cord AVMs, and particles over 1000 micros in diameter for cerebral AVMs. RESULTS Delivery of the embolic material was easy: microspheres did not aggregate and catheters did not become obstructed by particles. It was possible to control the embolization through precise accounting of the amount of microspheres and matching of the particle size to the size of the pathologic vascular network. CONCLUSION The microspheres are easy to use and allow precise control of the embolization procedure. Their physical characteristics make them a safe embolic agent.

Hemangiomas of the head, neck, and chest with associated vascular and brain anomalies: a complex neurocutaneous syndrome.

Abstract: PURPOSE To describe the vascular and nonvascular intracranial and extracranial anomalies associated with hemangiomas and vascular malformations of the face, neck, and/or chest. METHODS Seventeen patients had a physical examination and imaging studies consisting of one or more of the following: pneumoencephalography, conventional carotid and vertebral arteriography, CT, MR imaging, and MR angiography. RESULTS Conventional arteriography revealed persistence of the trigeminal artery in 5 cases, absence of internal or external carotid and/or vertebral arteries in 11 cases, persistence of intervertebral arteries in 1 case, deformities of the aortic arch in 3 cases, and anomalies of the intracranial arteries in 3 cases. MR angiography revealed persistence of the trigeminal artery in 1 case in which conventional arteriography failed to show the malformation, and permitted visualization of narrowing of the intracranial arteries. CT and MR imaging showed a cerebellar anomaly in 8 cases and cerebral cortical dysplasia with cerebral hemispheric hypoplasia in 1 case. Vascular and nonvascular anomalies appeared ipsilateral to the external vascular abnormalities in most cases. CONCLUSION This study demonstrates the association of cutaneous angiomas with anomalies affecting intracranial and extracranial arteries, the cerebellum, and, less frequently, the cerebral hemispheres and aortic arch. This association constitutes a relatively frequent neurocutaneous disorder, which we call the cutaneous hemangioma-vascular complex syndrome.

Cerebral aneurysms: evaluation with three-dimensional CT angiography.

Abstract: PURPOSE: To evaluate the usefulness of three-dimensional CT angiography (CTA), in which contrast material is used to create reformations of dynamic scans, in the diagnosis and the preoperative evaluation of cerebral aneurysms. METHODS: We used 3-D CTA to examine 65 patients with suspected or angiographically verified cerebral aneurysms. A blind study was performed to evaluate the diagnostic accuracy of 3-D CTA for cerebral aneurysms with the use of conventional angiography as the reference standard. RESULTS: In 50 patients, conventional angiography revealed 73 cerebral aneurysms ranging from 2 to 32 mm in maximum diameter. Three of the 73 cerebral aneurysms were located outside the imaging volume of 3-D CTA. The sensitivities of the two neuroradiologists for the remaining 70 aneurysms were 67% and 70%, respectively. Although 3-D CTA depicted cerebral aneurysms 5 mm or larger with good accuracy, it was less useful for the detection of smaller aneurysms. For the evaluation of giant aneurysms, this technique elucidated the relationships among the aneurysm, surrounding arteries, and neighboring bone structure. CONCLUSION: Three-dimensional CTA is useful for the diagnosis of cerebral aneurysms with diameters of 5 mm or more. This technique is especially useful in the preoperative evaluation of giant aneurysms.

Normal appearance of arachnoid granulations on contrast-enhanced CT and MR of the brain: differentiation from dural sinus disease.

Abstract: PURPOSE To determine the imaging appearance and frequency with which arachnoid granulations are seen on contrast-enhanced CT and MR studies of the brain. METHODS We retrospectively reviewed 573 contrast-enhanced CT scans and 100 contrast-enhanced MR studies of the brain for the presence of discrete filling defects within the venous sinuses. An anatomic study of the dural sinuses of 29 cadavers was performed, and the location, appearance, and histologic findings of focal protrusions into the dural sinus lumen (arachnoid granulations) were assessed and compared with the imaging findings. RESULTS Discrete filling defects within the dural sinuses were found on 138 (24%) of the contrast-enhanced CT examinations. A total of 168 defects were found, the majority (92%) within the transverse sinuses. One third were isodense and two thirds were hypodense relative to brain parenchyma. Patients with filling defects were older than patients without filling defects (mean age, 46 years versus 40 years). Discrete intrasinus signal foci were noted on 13 (13%) of the contrast-enhanced MR studies. The foci followed the same distribution as the filling defects seen on CT scans and were isointense to hypointense on T1-weighted images, variable in signal on balanced images, and hyperintense on T2-weighted images. Transverse sinus arachnoid granulations were noted adjacent to venous entrance sites in 62% and 85% of the CT and MR examinations, respectively. Arachnoid granulations were found in 19 (66%) of the cadaveric specimens, in a similar distribution as that seen on the imaging studies. CONCLUSION Discrete filling defects, consistent with arachnoid granulations, may be seen in the dural sinuses on 24% of contrast-enhanced CT scans and on 13% of MR studies. They are focal, well-defined, and typically located within the lateral transverse sinuses adjacent to venous entrance sites. They should not be mistaken for sinus thrombosis or intrasinus tumor, but recognized as normal structures.

Intraarterial thrombolysis in vertebrobasilar occlusion.

Abstract: PURPOSE: To report our experience using intraarterial thrombolysis in the treatment of vertebrobasilar occlusion. METHODS: Twelve patients with 13 angiographically proved thromboses of the vertebrobasilar system underwent local intraarterial thrombolysis with urokinase. Angiographic and clinical outcomes were analyzed with respect to clinical examination at presentation, arterial occlusion patterns, and time to recanalization. RESULTS: The overall mortality was 75%. Recanalization could not be achieved in 3 of 13 treatments; all patients in whom recanalization failed died. The mortality rate was 60% in those patients in whom recanalization was successful. Coma or quadriparesis at the time of therapy uniformly predicted death. There were two cases each of bilateral proximal vertebral occlusions and midbasilar occlusions and nine cases of bilateral distal vertebral occlusions. There were three cases of fatal rethrombosis after initial successful thrombolysis. The mortality rate in the recanalized group before rethrombosis was 30%. There were two fatal hemorrhages of the central nervous system. CONCLUSION: Recanalization of the vertebrobasilar system is necessary but not sufficient for effective treatment of vertebrobasilar occlusive disease. The site of occlusion may help predict angiographic and clinical outcome. Time to initiation of thrombolysis is not an invariable correlate of survival, although clinical condition at presentation may be. Rethrombosis and hemorrhage are significant problems affecting mortality after successful thrombolysis.

MR of carcinoma-specific monoclonal antibody conjugated to monocrystalline iron oxide nanoparticles : The potential for noninvasive diagnosis

Abstract: PURPOSE To determine if tumor-specific monoclonal antibodies conjugated to superparamagnetic monocrystalline iron oxide nanoparticles can be used to yield specific diagnoses with the use of MR imaging. METHODS Monoclonal antibodies conjugated to monocrystalline iron oxide nanoparticles were given to nude rats with intracranial tumors either by intravenous injection, intraarterial injection with osmotic blood-brain barrier disruption, or direct intratumoral inoculation. Either L6, a tumor-specific antibody, or P-1.17, a control isotype-matched antibody, was used. Coronal T1-weighted, T2-weighted, and spoiled gradient-recalled acquisition in the steady state images were obtained before, 30 minutes after, 6 hours after, and 24 hours after injection. RESULTS Intravenous injection of greater than 2 mg of the tumor-specific antibody showed a specific pattern of enhancement of the tumors with the largest concentration of antibody in the area with the greatest density of tumor cells. The control antibody showed nonspecific changes. After intraarterial injection with barrier disruption to increase delivery globally or direct inoculation to increase delivery focally, no specific enhancement pattern was seen. CONCLUSION Monoclonal antibodies conjugated with monocrystalline iron oxide particles may provide a method to obtain specific diagnoses with the use of MR imaging.

A proposed model of cerebrospinal fluid circulation: observations with radionuclide cisternography.

Abstract: PURPOSE To determine the mechanisms of the tracer distribution at radionuclide cisternography (RC). METHODS Ten patients with venous vasculitis were studied with RC. Flow phantom studies were performed mimicking cerebrospinal fluid (CSF) circulation with and without a main outlet comparable to the pacchionian granulations. RESULTS Nine of the 10 patients had normal findings on RC images, including a maximum uptake over the vertex at 24 hours. In all patients, a second maximum occurred in the lumbosacral area. The flow phantom studies showed no tracer accumulation at an open outlet corresponding to the pacchionian granulations. On the contrary, a maximum arose without such an outlet. A maximum always arose at the closed dead ends of the phantom, including the lumbosacral area. CONCLUSION The commonly accepted flow model for CSF circulation needs to be revised. The pattern of the normal RC cannot be explained by a bulk flow transport of the tracer to an outlet at the pacchionian granulations but rather by a primary mixing caused by pulsatile flow with a secondary dilution by newly formed CSF from the ventricular system. We suggest that the main absorption of the CSF is through the central nervous system to the blood.

Three-dimensional CT Angiography in the Detection and Characterization of Intracranial Berry Aneurysms

Abstract: PURPOSE To assess the accuracy of three-dimensional CT angiography (CTA) in the detection and characterization of intracranial aneurysms and to help determine its role as a screening test for aneurysms in the asymptomatic population and as an adjunct to angiography in subarachnoid hemorrhages and in the follow-up of untreated aneurysms. METHODS In a blinded, prospective study, the 3-D CTA studies in 80 patients with symptomatic aneurysms were analyzed for the presence and morphology of aneurysms. Angiography or surgery acted as the control. RESULTS Ninety-four aneurysms were found in 63 patients. Negative findings at angiography were noted in 17. Sensitivity and specificity of 3-D CTA for all aneurysms, all patients, and aneurysms 5 mm or smaller were 90.4% and 50%, 98.4% and 82.4%, and 78.8% and 51.9%, respectively. CONCLUSION Three-dimensional CTA may have a role in noninvasive screening for asymptomatic aneurysms in the general population, but caution is advocated when data obtained from symptomatic patients are extrapolated to the asymptomatic population who harbor smaller aneurysms. Also, 3-D CTA may be useful as an adjunct to angiography in the characterization of berry aneurysms and in the follow-up of untreated aneurysms.

Linear measures of atrophy in mild Alzheimer disease.

Abstract: PURPOSE To assess the sensitivity of linear measures of brain atrophy in the diagnosis of Alzheimer disease (AD) in the early stages. METHODS Linear measures of regional frontal (Bifrontal index, interhemispheric fissure width), medial temporal lobe (interuncal distance, minimum thickness of the medial temporal lobe), and hippocampal (hippocampal height, width of the choroid fissure, width of the temporal horn) atrophy were made on magnified MR images obtained in 46 patients with AD (33 with mild severity and 13 with moderate severity) and in 31 control subjects. Gaussian modeling was used to compute sensitivity with specificity set at 95%. Discriminant analysis was used to identify measures independently contributing to the ability to discriminate AD patients from control subjects. RESULTS The measure with the best sensitivity in discriminating AD patients from control subjects was the width of the temporal horn. A compound measure of width of the temporal horn, width of the choroid fissure, height of the hippocampus, and interuncal distance could discriminate patients with mild AD from control subjects with 86% sensitivity. Cross validation in patients with moderate AD confirmed the usefulness of the model (81% sensitivity). Measures of hippocampal atrophy alone could discriminate patients with mild AD from control subjects with 83% sensitivity; in patients with moderate AD, cross validation produced 87% sensitivity. CONCLUSIONS Linear measures of hippocampal atrophy can be a useful adjunct in the routine diagnosis of AD, even in its early stages.

Preoperative endovascular embolization of craniospinal hemangioblastomas

Abstract: PURPOSE To determine whether hemangioblastomas, highly vascular tumors requiring surgery that is potentially complicated by excessive bleeding, can be embolized safely by using interventional techniques that furnish a more avascular surgical field. METHODS Nine hemangioblastomas involving either the cerebellum or the spinal cord were embolized preoperatively. In each case the feeding artery was selectively catheterized with a microcatheter and the hypervascular tumor nidus was devascularized with polyvinyl alcohol particles. RESULTS Two patients who had undergone recent attempts as surgical resection at another institution had repeat surgery after endovascular embolization rendered the tumor nidus avascular. At surgery, the tumor was completely removed in one case and markedly debulked in the other. In all nine cases, blood loss after embolization was reported to be less than expected by experienced surgeons. In addition, manipulation and removal of the tumor was reported to be subjectively easier in these embolized tumors. The embolization procedure caused no permanent complications; however, one patient with a posterior fossa hemangioblastoma and hydrocephalus worsened clinically within 12 hours of embolization. This event was thought to be caused by obstructive hydrocephalus resulting from tumor swelling. Emergency craniotomy, ventricular decompression, and surgical resection of the tumor produced complete resolution of the signs and symptoms. CONCLUSIONS Our results indicate that preoperative embolization of hemangioblastomas is a safe procedure that is useful in aiding surgical resection of these highly vascular tumors.

Craniopharyngioma: radiologic and histologic findings and recurrence.

Abstract: Purpose To identify the CT and MR characteristics of craniopharyngiomas, to evaluate the histologic types of craniopharyngioma, and to compare the radiologic/histologic appearance and type of therapy with tumor recurrence. Methods We reviewed the records of 45 patients with craniopharyngiomas for which surgical specimens (n = 45), preoperative MR or CT studies (n = 27), or other MR or CT studies or reports (n = 18) were available. Radiologic appearance, histologic morphology, treatment, and tumor recurrence were studied. Results Adamantinomatous epithelium was found in 40 of 45 surgical specimens, keratin in 34 of 45, and squamous epithelium in 11 of 45. A continuum of mixed morphology rather than distinct subtypes of tumors was found. The radiologic appearance did not correlate with the histologic features. No statistically significant difference was found between children and adults with respect to tumor size, calcification, histology, or tumor recurrence. Patients treated with radiation after subtotal resection had far fewer tumor recurrences (n = 3) than patients treated with surgery alone (n = 18). Conclusion Craniopharyngiomas could not be divided into distinct histologic types. No differentiating radiologic or histologic characteristics could be established for craniopharyngiomas in children versus adults. Radiation treatment was strongly associated with tumor regression or lack of recurrence.

Dysembryoplastic neuroepithelial tumors: MR and CT evaluation.

Abstract: PURPOSE To evaluate dysembryoplastic neuroepithelial tumors (DNTs) on MR and CT studies and to compare DNT with other frequently encountered epileptogenic glioneuronal lesions. METHODS We analyzed the MR images and CT scans of 16 patients who had complex partial epilepsy and DNT with respect to tumor location, size, CT density, MR signal intensity, mass effect, contrast enhancement, and heterogeneity, and compared these features with CT and MR findings in 51 cases of ganglioglioma and 33 cases of glioneuronal malformation. RESULTS DNTs were located in the temporal lobe in 14 patients and in the frontal lobe in 2 patients. The cortex was involved in all cases and the subcortical white matter in 10 cases. Fifty percent of the tumors had poorly defined contours. On MR images, 14 DNTs had multiple cysts and 2 had single cysts. Contrast enhancement was observed in 6 DNTs, and mass effect was present in 9. CT scans disclosed moderately hypodense lesions in 7 patients and markedly hypodense cystic lesions in 6 patients. Two DNTs were calcified. Tumor hemorrhage with perifocal edema was observed in 1 case. Contrary to previous reports, slow but definite tumor growth was present during a 13-year period in 2 of 6 patients in whom serial CT or MR studies were obtained. CONCLUSION A multicystic appearance on MR images is a characteristic feature of DNT and corresponds to its myxoid matrix and multinodular architecture. This feature is rare in gangliogliomas and glioneuronal malformations, and, as such, may help differentiate DNTs from these disorders.

Preoperative Percutaneous Injection of Methyl Methacrylate and N-Butyl Cyanoacrylate in Vertebral Hemangiomas

Abstract: PURPOSE: To investigate the usefulness of preoperative percutaneous injections in vertebral hemangiomas. METHODS: Four patients presented with complicated vertebral hemangioma (spinal cord compression in three cases, intermittent spinal claudiction in one case). A three-part treatment was performed: initially, arterial embolization in three cases; 1 day later, percutaneous injections of methyl methacrylate into the vertebral body to strengthen it and of N-butyl cyanoacrylate into the posterior arch to optimize hemostasis during surgery; finally, the day after percutaneous injections, decompressive laminectomy and epidural hemangioma excision (when present). RESULTS: Laminectomy was performed with minimal blood loss. The epidural component present in three cases was excised without any difficulty. The follow-up (average, 20 months) showed no evidence of vertebral collapse. CONCLUSION: Percutaneous injections of methyl methacrylate and N-butyl cyanoacrylate might be useful before surgery for vertebral hemangiomas.

Clinical positron emission tomography for brain tumors: comparison of fludeoxyglucose F 18 and L-methyl-11C-methionine.

Abstract: PURPOSE To evaluate the differences between fludeoxyglucose F 18 (FDG) and L-methyl-11C-methionine (11C-methionine) as tracers for positron emission tomography (PET) in the evaluation of brain tumors. METHODS We analyzed 10 patients with histologically verified cerebral glioma or meningioma and 1 patient with a neuroradiologic diagnosis of low-grade glioma by using FDG, 11C-methionine, and PET. We qualitatively and quantitatively evaluated the extent and degree of accumulation of FDG and 11C-methionine in the tumor tissue. RESULTS Although PET with FDG depicted malignant tumors as a hot spot in all cases, it was not able to delineate the extent of the tumor. Conversely, PET with 11C-methionine outlined the tumors as areas of increased accumulation of 11C-methionine, regardless of the degree of malignancy. CONCLUSION PET with FDG and with 11C-methionine can play complementary roles in the evaluation of brain tumors.

MR determination of hippocampal volume: comparison of three methods

Abstract: PURPOSE To determine whether measurements of the volume of the hippocampal formation obtained from a three-dimensional acquisition not perpendicular to the hippocampus are statistically different from those obtained from a perpendicular acquisition. METHODS Both hippocampi were studied in 10 healthy volunteers with two three-dimensional acquisitions, allowing three different volume-calculation protocols: (a) on sections from a coronal 3-D acquisition not perpendicular to the axis of the hippocampal formation (NOPERP protocol), (b) on sections obtained with the same acquisition but reformatted perpendicular to the axis of the hippocampal formation (REFOR protocol), and (c) on sections from a coronal 3-D acquisition perpendicular to the axis of the hippocampal formation (PERP protocol) obtained with the patient's head tilted backward. To obtain measurements of the volume of the hippocampal formations, an accurate 3-D processing technique was used to segment the hippocampus. In all subjects, two hippocampal formation right-left asymmetry indexes were calculated by using each of the three protocols. RESULTS For the right hippocampus, the mean volume was 3.42 cm3 (NOPERP protocol), 4.18 cm3 (REFOR protocol), and 3.91 cm3 (PERP protocol). For the left hippocampus, the mean volume was 3.29 cm3 (NOPERP protocol), 4.02 cm3 (REFOR protocol), and 3.74 cm3 (PERP protocol). For both hippocampi, the differences of the mean volumes were significant between each protocol. However, for both hippocampi, a high correlation was observed between volumes obtained with the different protocols. For the two asymmetry indexes, there were no significant differences for the means obtained with the three protocols. CONCLUSION With the use of 3-D acquisitions in the study of hippocampal formation biometry, different procedures lead to significant variations in the absolute values of the volume of the hippocampal formation. However, there is a strong correlation between the results obtained by each method.

Intraorbital wooden foreign body: CT and MR appearance

Abstract: A case of an intraorbital wooden foreign body mimicking air on standard CT window setting and on MR is presented. Its higher attenuation with higher CT window setting as well as its elongated and well-delineated shape on both CT and MR helped to distinguish it from air.

Spinal cord lesions in patients with multiple sclerosis: comparison of MR pulse sequences

Abstract: PURPOSE To compare T2-weighted conventional spin-echo (CSE), fast spin-echo (FSE), shorttau inversion recovery (STIR) FSE, and fluid-attenuated inversion recovery (FLAIR) FSE sequences in the assessment of cervical multiple sclerosis plaques. METHODS Twenty patients with clinically confirmed multiple sclerosis and signs of cervical cord involvement were examined on a 1.5-T MR system. Sagittal images of T2-weighted and proton density-weighted CSE sequences, T2-weighted FSE sequences with two different sets of sequence parameters, STIR-FSE sequences, and FLAIR-FSE sequences were compared by two independent observers. In addition, contrast-to-noise measurements were obtained. RESULTS Spinal multiple sclerosis plaques were seen best on STIR-FSE images, which yielded the highest lesion contrast. Among the T2-weighted sequences, the FSE technique provided better image quality than did the CSE technique, but lesion visibility was improved only with a repetition time/echo time of 2500/90; parameters of 3000/150 provided poor lesion contrast but the best myelographic effect and overall image quality. CSE images were degraded by prominent image noise; FLAIR-FSE images showed poor lesion contrast and strong cerebrospinal fluid pulsation artifacts. CONCLUSIONS The STIR-FSE sequence is the best choice for assessment of spinal multiple sclerosis plaques. For T2-weighted FSE sequences, shorter echo times are advantageous for spinal cord imaging, long echo times are superior for extramedullary and extradural disease. FLAIR-FSE sequences do not contribute much to spinal imaging for multiple sclerosis detection.