Meningioma in four patients with human immunodeficiency virus infection

We describe four patients infected with the human immunodeficiency virus (HIV) who had development of meningiomas. In contrast to those in the general population who have meningiomas, all our patients were young men; the mean age was 40 years (range, 32 to 50). Their risk behavior for HIV was homosexuality (three patients) and intravenous drug use (one patient). The CD4+ cell count in each of the three homosexual men was less than 50/microL and was 280/microL in the drug user. Imaging studies showed enhancing lesions in three of the patients. Although each of these meningiomas could have occurred in otherwise normal young to middle-aged men, we speculate that the meningiomas may have grown in these HIV-infected hosts because of either loss of immune function or dysregulation of cytokines.

Image-guided endoscopic surgery: results of accuracy and performance in a multicenter clinical study using an electromagnetic tracking system

Image-guided surgery has recently been described in the literature as a useful technology for improved functional endoscopic sinus surgery localization. Image-guided surgery yields accurate knowledge of the surgical field boundaries, allowing safer and more thorough sinus surgery. We have previously reviewed our initial experience with The InstaTrak System. This article presents a multicenter clinical study (n=55) that assesses the system's capability for localizing structures in critical surgical sites. The purpose of this paper is to present quantitative data on accuracy and performance. We describe several new advances including an automated registration technique that eliminates the redundant computed tomography scan, compensation for head movement, and the ability to use interchangeable instruments.

Imaging of the sella in the syndrome of inappropriate secretion of antidiuretic hormone

OBJECTIVE

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) results either from ectopic production or inappropriate release of antidiuretic hormone from the neurohypophysis. Although magnetic resonance imaging (MRI) has provided new insights into the morphological changes of the hypophysis in health and disease, no previous studies have evaluated its use in SIADH: The aim of this study was to evaluate the MRI appearance of the neurohypophysis in patients with SIADH:

DESIGN

Retrospective case-control study.

SETTING

Tertiary care teaching hospital.

SUBJECTS

We studied retrospectively eight patients with SIADH who had been hospitalized in Boston's Beth Israel between 1984 and 1994 and who had MRI scans including the sella turcica. We also evaluated prospectively the MRIs of the heads of 23 consecutive control patients who had no pituitary pathology and no serum osmolality or electrolyte abnormalities.

INTERVENTIONS

Clinical evaluation as well as sagittal and axial T1-MR images.

MAIN OUTCOME MEASURES

Presence or absence of the high intensity signal of the neurohypophysis.

RESULTS

In seven out of eight patients (87.5%) the normal high intensity signal of the neurohypophysis was not present. In one patient (12.5%), two interpreting radiologists disagreed about its presence. The high intensity signal was present in the neurohypophysis of 20 out of 23 controls (87.5%).

CONCLUSIONS

Our data indicate an association of SIADH with the absence of the normal hyperintense signal of the neurohypophysis, confirming the usefulness of MRI as a tool to visualize ADH processing. These data also raise the possibility that the absence of the high intensity signal may be useful diagnostic tool in cases of SIADH that are difficult to diagnose clinically. Additional studies to correlate this signal with various forms of SIADH will be needed.

Transaqueductal migration of a neurocysticercus cyst. Case report

The clearly documented transaqueductal migration of a solitary intraventricular neurocysticercus cyst is described. The cyst was fortuitously demonstrated on magnetic resonance imaging during migration through the aqueduct. The radiological appearance and clinical significance of this condition are discussed.

Improved time-of-flight MR angiography of the brain with magnetization transfer contrast

The authors hypothesized that magnetization transfer contrast (MTC) could be used to improve flow contrast in time-of-flight (TOF) magnetic resonance (MR) angiography. Two- and three-dimensional flow-compensated gradient-echo images were obtained with and without MTC. MTC images were obtained by applying low-power radio-frequency (RF) radiation with a frequency offset from the bulk "free" water resonance frequency before the excitation RF pulse. The signal intensity of stationary tissue decreased as the power applied for the MTC pulse was increased. A smaller decrease occurred in venous signal intensity as measured in the superior sagittal sinus, and less change was seen in the arterial signal intensity as measured in the middle cerebral artery. Cerebrospinal fluid showed no MTC effect. The use of MTC improved small-vessel depiction on maximum-intensity projection images. The authors conclude that use of MTC can substantially enhance the quality of TOF MR angiography of the brain.

MR angiography of the extracranial carotid arteries using a two-slab oblique 3-D acquisition

PURPOSE

To describe an oblique, two-slab 3-D acquisition technique for MR angiography of the extracranial carotid arteries, an approach chosen to minimize saturation effects when the body coil is used as transmitter, as is often the situation when a dedicated neck coil is used as receiver.

SUBJECTS

Five healthy subjects and 17 patients in whom carotid artery disease was suspected underwent MR angiography using the above technique.

RESULTS

Flow contrast was much better than in direct sagittal acquisition. Comparisons between multislab transverse 3-D acquisition and the oblique approach showed that a greater length of the carotid arteries was depicted and scan time was less for oblique acquisitions.

CONCLUSIONS

Use of oblique imaging is a simple and effective solution to the problem of coil-related saturation effects.

Degenerative disorders of the cervical spine

Magnetic resonance imaging is the study of choice in patients with suspected degenerative discogenic disease. It is a sensitive diagnostic modality offering multiplanar imaging capability and excellent soft-tissue and spatial resolution without ionizing radiation. Physiologic information, primarily relating to water content, is provided as is a myelographic effect, without the risks of intrathecal contrast. Computed tomography remains a valuable adjunct in those patients with extensive bony degenerative changes.

Rheumatoid arthritis of the cervical spine

This article discusses the pathologic and radiologic changes in the cervical spine that occur with rheumatoid arthritis. The relevance of radiologic evaluation using radiographs, conventional tomography, myelography, computed tomography, computed tomography-myelography, and magnetic resonance imaging is discussed. Magnetic resonance imaging is the pre-eminent radiologic modality in the examination of cervical rheumatoid arthritis.

Right hemisphere advantage for evaluating emotional facial expressions

The ability to evaluate the intensity of emotional facial expressions was investigated in patients undergoing the intracarotid sodium amytal procedure. It was found that when the hemisphere non-dominant for language (usually right) was anesthetized, the patients' ratings of the intensity of emotional expressions in photographs were lower than baseline ratings of these expressions. Such an effect was not seen with anesthetization of the hemisphere dominant for language (usually left). Ratings of shades of gray (which served as control stimuli) showed no such effect. The findings are interpreted in terms of a right hemisphere superiority in the perception and evaluation of emotional expression.

Cerebral venography with MR

The authors describe a two-dimensional time-of-flight magnetic resonance (MR) angiography technique to create projection venograms of the head. The technique was applied to 27 healthy volunteers and 39 patients. The superior sagittal and straight sinuses, the internal cerebral veins, and the Galen vein were visualized in all the volunteers. Other veins were seen in a high percentage of subjects. Systematic comparison of digital subtraction angiography (DSA) after intraarterial contrast medium injection and MR venography in patients showed good correlation between the two techniques. MR venography proved helpful in identifying thrombosis or patency of cerebral veins and sinuses and showed collateral venous drainage and venous drainage from arteriovenous malformations. There was good correlation between conventional contrast angiography and MR venography. In conclusion, MR venography is considered reliable for showing the cerebral venous system and provides information additional to that of conventional spin-echo imaging.

Stereoscopic display of MR angiograms

Recent developments in magnetic resonance (MR) allow high resolution imaging of flowing blood. To overcome the tomographic nature of conventional MR acquisitions, projection angiograms can be produced. These angiograms are similar in their display of blood vessels to plain film or digital subtraction angiograms. However, the three-dimensional information inherent in them is partly lost when single projections are viewed. We describe a method of three-dimensional display consisting of stereo pairs of the MR angiograms. With these an examiner experienced in stereo viewing can recover depth perception.

Extracranial carotid arteries: evaluation with "black blood" MR angiography

The authors evaluated the accuracy of "black blood" magnetic resonance (MR) angiography for depicting disease involving the extracranial carotid arteries. Two- and three-dimensional flow-compensated gradient-echo sequences were employed to create "bright blood" images. A thin-section spin-echo sequence with flow presaturation allowed the creation of black blood images. Projection angiograms were made from bright and black blood images with application of a maximum- or minimum-intensity projection algorithm, respectively. These methods were used in 13 healthy volunteers and 17 patients, and a prospective blinded comparison of MR angiography and conventional angiography was performed. Normal carotid arteries were well shown with both bright and black blood methods; in patients, both methods were sensitive for detecting carotid disease. However, bright blood angiography exaggerated the severity of carotid lesions in 13 of 33 arteries, mostly in severe disease; this problem was not encountered with black blood angiography. The authors conclude that bright blood angiography is a sensitive method for screening carotid disease; when a significant abnormality is found, black blood angiography should be performed for more precise delineation of the lesion.

Visual neglect during intracarotid amobarbital testing

The unilateral suppression of hemispheric function by sodium amobarbital may result in hemispatial visual neglect, as measured by performance on a random letter cancellation task. Our study not only investigates this hypothesis but also attempts to identify more precisely the anatomic locus of control for directed attention to extrapersonal space by correlating scanning performance with EEG activity. Forty-eight consecutive patients with epilepsy underwent preoperative intracarotid amobarbital tests. The results indicated that disruption of scanning and contralateral neglect occurred only after right-hemisphere suppression and seemed specifically related to changes in right frontal lobe EEG activity. This pattern of performance held not only for right-handed subjects, but also for those who were left-handed, and even for those who had right-hemisphere language dominance.

Cerebral blood flow: assessment with dynamic contrast-enhanced T2*-weighted MR imaging at 1.5 T

The authors assessed regional cerebral blood flow dynamics with magnetic resonance (MR) imaging enhanced with gadolinium diethylenetriaminepentaacetic acid (DTPA). After bolus administration of Gd-DTPA, rapid T2*-weighted gradient-echo images were acquired. Image acquisition time ranged from 2 to 3 seconds. The signal intensity (SI) of brain tissue and blood vessels markedly decreased during the first pass of contrast agent through the brain due to the local field inhomogeneity caused by the concentrated paramagnetic contrast agent. The method was used in 18 subjects with no cerebrovascular disease and 32 patients with stroke, vascular stenosis, arteriovenous malformation, and cerebral neoplasm. Comparison with intracranial angiography was performed in three patients and with single-photon emission computed tomography of blood flow in four. The change in T2* relaxation rate was approximately linearly related to the dose of contrast agent. The SI change increased as the echo time was lengthened. Regions in cerebral infarcts, metastases, and arteriovenous malformations showed different enhancement patterns than those of edema around a lesion and of normal brain tissue. Abnormal circulation times in patients with vascular stenoses were demonstrated. The method provides information about cerebral blood flow dynamics not available from conventional MR imaging and MR angiography.

Quantification of blood flow with dynamic MR imaging and presaturation bolus tracking

A technique is described for rapid imaging of blood flow and dynamic measurement of its velocity. The method is a combination of bolus tracking and low-flip-angle gradient-echo cine angiography. This method provides precise determination of velocity with high temporal resolution in a single measurement. Unlike what occurs in phase imaging techniques, flow is displayed directly, eliminating potential errors that result from non-flow-related sources of phase shifts. Manipulation of raw data sets is avoided. Results obtained from a flow phantom, healthy volunteers, and a patient with an aortic aneurysm demonstrate the capability of the technique to track flow at low and high velocities and to differentiate flowing blood from thrombus. Because of its conceptual simplicity, rapidity, and lack of susceptibility to extraneous phase shifts, this technique may prove ideal for in vivo flow measurement and evaluation of flow patterns.

Embolization of solitary spinal metastases from renal cell carcinoma: alternative therapy for spinal cord or nerve root compression

Four patients with a solitary vertebral metastasis from a renal cell carcinoma presented with acute spinal cord or nerve root compression. Because of the markedly hypervascular nature of the metastases it was decided to palliate the lesions by transarterial catheter embolization. The embolization reduced the venous blood pool within the tumors, resulting in progressive neurological improvement often lasting for 12 weeks or more. With such palliation, surgical decompression may be obviated, postponed, or at least made manageable.

Biplane stereoscopic magnification cerebral angiography

An angiographic system capable of simultaneous biplane stereoscopic magnification cerebral angiography was evaluated. Stereoscopic imaging improved the morphologic depiction of aneurysms and of arteriovenous malformations. In a series of 357 patients, procedure time was reduced because the initial biplane stereoscopic series was nearly always diagnostic, obviating the need for additional angiographic views.

Craniopharyngioma in an elderly patient

Craniopharyngioma, a tumor most commonly diagnosed in the young, may occur at any age. The oldest patient known to have histologic documentation of a craniopharyngioma, an 82.5-year-old woman, presented with visual field changes, panhypopituitarism, and mental status changes. This diagnosis should be considered in such patients, because craniopharyngioma is a potentially curable tumor by either surgery or radiation therapy.

Cerebral infarction: shortcomings of angiography in the evaluation of intracranial cerebrovascular disease in 25 cases

We studied the utility and limitations of conventional cerebral angiography in 25 patients with cerebral infarction unassociated with extracranial cerebrovascular disease during a 7-year period. In only one-third of cases was the angiogram diagnostic, and in a single case it altered the pre-angiogram diagnosis by revealing a previously unsuspected embolus. Among the cases clinically diagnosed as cerebral emboli, the 2 confirmatory angiograms were performed early (within 48 hours), and demonstrated medium-large or large vessel filling defects. Two-thirds of the negative angiograms in the embolic clinical category were delayed, but there was no statistically relevant predilection for specific vessel size involvement. The category, primary cerebral vasculopathy, comprised the largest group, 10 in all, and one-half had angiographic confirmation despite time delays. Angiographic recognition was dependent on a characteristic picture of vascular involvement, and not on timing or vessel size predilection. Mitral valve prolapse figured prominently in the clinical cases of vasculopathy of uncertain etiology, which contained a total of 4 cases. The 3 cases with nondiagnostic angiograms were all delayed and demonstrated nonspecific radiographic changes. Clinically, these cases demonstrated signs or symptoms of autoimmune dysfunction, raising the specter of primary cerebral vasculopathy as a cause of cerebral infarction, in contrast to recurrent cerebral emboli.

Thoracic chordoma with unusual radiographic features

A case of chordoma involving the thoracic spine (T12) is reported. The plain film findings included lytic obstruction and partial collapse of a single vertebral body. Noncontrast CT and CT following Metrizamide myelography revealed vertebral body destruction with paravertebral and intraspinal soft tissue masses. Unusual findings in the case included a photon deficient area on nuclear medicine corresponding to the lesion and normal vascularity on spinal angiography. We know of no previous report describing chordoma as a "cold" defect on bone scanning.

Neuroimaging and the lesion of multiple sclerosis

In a patient with long-standing multiple sclerosis (MS), a double-dose delayed contrast-enhanced CT scan obtained during exacerbation revealed many areas of enhancement. Vigorous treatment with corticotropic hormone was followed by almost complete disappearance of these abnormalities. No areas of low attenuation were seen on a later unenhanced CT scan. Finally, MR imaging showed only a single area compatible with a plaque of MS. It is suggested that pathologic alteration of the blood-brain barrier seen in MS is not necessarily followed by demyelination and plaque formation. Restoration of the integrity of the blood-brain barrier may thus possibly prevent the formation of plaques in some MS patients, in particular if this can be accomplished early in the course of the exacerbation.

Balloon occlusion of a recurrent carotid-cavernous fistula previously treated by carotid ligations

A carotid-cavernous fistula recurred 16 years after a Hamby procedure. The recurrence was manifested by subarachnoid hemorrhage originating from dilated draining pial veins. The fistula was closed with a balloon catheter introduced through a patent remnant of the cervical carotid artery. Patients who have previously undergone Hamby trapping and embolization should be reassessed for an occult fistula that could predispose them to intracranial bleeding.

The clinical spectrum of hemorrhagic infarction

The hospital records and head CT scans of 44 patients with hemorrhagic infarction were retrospectively analyzed. The majority of cases (73%) were embolic or possibly embolic in etiology, and 55% were not associated with anticoagulant therapy. Adverse prognosis was most clearly related to infarct size, underlying systemic illness, and symptomatic hemorrhage. Of the nineteen patients in whom serial CT scans documented conversion from bland to hemorrhagic infarction, 12 exhibited no clinical worsening at the time that hemorrhagic infarction was observed; the remaining seven, all of whom worsened, were receiving anticoagulant therapy at the time of documented conversion. Fourteen patients in whom anticoagulant therapy was used despite the findings of hemorrhagic infarction remained stable or improved during hospitalization.

Progressive polyradiculopathy in acquired immune deficiency syndrome

We studied three patients with acquired immune deficiency syndrome (AIDS) and progressive polyradiculopathy. Postmortem examination of one patient disclosed extensive necrosis, inflammatory infiltrates, and focal vasculitis of spinal roots. Typical cytomegaloviral (CMV), intranuclear, and intracytoplasmic inclusions were noted within enlarged endoneurial and endothelial cells. Progressive polyradiculopathy is an unusual complication of AIDS; CMV may be the causative agent in certain cases.

Primary amenorrhea and pseudoprolactinoma in a patient with primary hypothyroidism. Reversal of clinical, biochemical, and radiologic abnormalities with levothyroxine

A 15-year-old girl presented with primary amenorrhea, galactorrhea, hyperprolactinemia and an enlarged pituitary gland. She proved to have primary hypothyroidism. Therapy with levothyroxine resulted in prompt induction of regular menses, normalization of hormone levels, and a reduction in the size of the pituitary. Although hypothyroidism is known to produce secondary amenorrhea, hyperprolactinemia, and pituitary enlargement, this is believed to be the first computed tomographic documentation of such a "pseudoprolactinoma" presenting as primary amenorrhea.

Fabrication of microballoons for interventional neuroradiology: preliminary report

A simple and inexpensive method of making latex microballoons for neuroradiologic procedures is described. The balloons have been tested in experimental animals and used in human clinical procedures. Preliminary experience and results are presented.

Iopamidol in lumbar myelography

Iopamidol is a new, nonionic, water-soluble contrast material currently undergoing clinical trials for intravascular and intrathecal use in Europe and the United States. In this study, 12 patients underwent lumbar myelography with this agent. For each subject, up to 12 mL of iopamidol (at 200 mg I/mL) was employed. The myelograms obtained were highly satisfactory. No serious adverse reactions were observed. The most common side effect--headache--occurred in seven patients. However, six of the seven headaches were mild and transient, and did not require treatment. Nausea occurred in two patients, back pain in two patients, hypotension and hypertension each in one patient. All of these reactions were mild and self-limited. Iopamidol appears to be a safe and conveniently used agent for lumbar myelography.

Cerebral hemisphere asymmetry in CT and functional recovery from hemiplegia

Cerebral hemispheric asymmetries were assessed in relation to motor and functional recovery in nine patients with stroke. All were globally aphasic, assuring similar location and extent of lesion. Initial motor and functional ability were appraised from medical records and compared with neurologic and functional outcome. Frontal and occipital hemispheric widths and lengths were determined from CT. Patients were classified into three groups on the basis of mean combined asymmetry for width (typical asymmetry, atypical asymmetry, and equal symmetry). Patients with the most atypical cerebral asymmetries showed greater recovery than patients in other groups. Two patients with atypical mean occipital asymmetry (width) fared best functionally, whereas the patient who showed the greatest motor recovery had the most atypical mean occipital asymmetry (width). Cerebral asymmetries may contribute to recovery after stroke.

Giant intracranial aneurysms of the anterior circulation: clinical characteristics and diagnosis by computed tomography

The computed tomography (CT) characteristics and clinical features of giant (globoid) aneurysms of the anterior circulation are reviewed. These lesions appear on the CT scan as smoothly encapsulated ovoid masses, within which a partially patent lumen is seen after the infusion of iodinated contrast material. With careful analysis of the CT scan it may be possible to differentiate giant internal carotid artery, anterior cerebral artery, and middle cerebral artery aneurysms from other parasellar and hemispheric lesions.

Computed tomography in metrizamide cisternography--importance of coronal and axial views

Computed tomographic scans were performed in 34 patients following lumbar introduction of metrizamide. Imaging of the cranial spaces was obtained with horizontal and inclined (25 degrees) as well as coronal planes. Mass lesions within and encroaching upon the cisternal spaces were demonstrated, and the ventricular system was shown with varying degrees of opacification. Coronal and semicoronal views facilitated the localization of parasellar and incisural mass lesions.

Computed tomography of tumors of the pineal region

Eight pathologically proven cases of pineal region tumors examined by computed tomography (CT) were found upon reviewing 11,000 consecutive CT studies at the Massachusetts General Hospital. The CT scan findings of the eight cases are described and related to a pathological classification of pineal tumors.