Safety and efficacy of sodium and meglumine ioxaglate (Hexabrix) and Hypaque M60% in contrast-enhanced computed cranial tomographic scanning. A double-blind clinical study.

The safety and efficacy of sodium and meglumine ioxaglate (Hexabrix, Mallinckrodt, Inc., St. Louis, MO), a new low-osmolality contrast agent, and Hypaque Meglumine 60% (Wintrop-Breon, Inc., New York, NY) were compared for contrast-enhanced computed cranial tomographic scanning. Fifty-two patients with possible enhancing lesions of the brain received a total of 59 injections of either Hexabrix or Hypaque M60 in a double-blind, randomized fashion. Hexabrix was superior to Hypaque M60 in both subjective and objective patient tolerance. A lower incidence of heat and pain in patients receiving Hexabrix was believed to be related to its lower osmolality. Lesion enhancement with both Hexabrix and Hypaque M60 was excellent. There was a statistically significant increase in the degree of enhancement immediately after injection with Hexabrix. Hexabrix had less effect on the cardiovascular system than Hypaque M60. No neurologic complications or adverse reactions requiring treatment occurred in either group. Hexabrix is a suitable agent for intravenous contrast-enhancement for cranial CT.

MR angiography of aneurysm models of various shapes and neck sizes.

PURPOSE: To investigate the signal intensity of lateral and terminal saccular aneurysm models with differing neck sizes using three-dimensional time-of-flight (TOF) MR angiography with various imaging parameters. METHODS: The study included four lateral and four terminal saccular aneurysm models with pulsatile flow. The height and fundus diameter were 10 mm; the neck diameters were 2.5 mm, 5 mm, 7.5 mm, and 10 mm, respectively. Each aneurysm model was examined with fast imaging with steady-state precession MR sequences with parameters of 20-140/7 (repetition time/echo time) and flip angles of 10 degrees to 30 degrees. Signal intensity was measured and compared among the models. RESULTS: Three-dimensional TOF MR angiography with the shorter repetition time and/or larger flip angle showed weaker signal intensity in the aneurysm models. Stronger signal intensity was obtained in the terminal saccular aneurysm models and/or the models with a wider neck than in the lateral saccular aneurysm models and/or the models with a narrower neck. In some aneurysm models, longer repetition times produced greater signal intensity than that of background brain models, but not in aneurysms with narrow necks. CONCLUSION: Noncontrast 3-D TOF MR angiography delineated terminal saccular aneurysms and/or aneurysms with wider necks and did not delineate lateral saccular aneurysms and/or aneurysms with narrower necks. Longer repetition times are recommended to allow the spins flowing into the aneurysms to recover.

Chemonucleation and changes observed on lumbar MR scan: preliminary report.

This study examines the relation between the postchemonucleation clinical outcome and changes observed on the lumbar MR scan. Eight of 12 chemonucleated disks showed clinical improvement at the last follow-up, while the other four showed no improvement. In the cases that showed improvement there was a decrease in one or both dimensions of the defect in the thecal sac. Seven of eight showed an increase in the peridisk signal. Where there was no clinical improvement there were fewer decreases in the size of the defect, and three of four showed no increase in the peridisk signal.

Extradural lymphoma presenting as an acute surgical emergency.

Extradural lymphoma can present as an acute neurosurgical emergency. The clinical presentation and radiological appearance may suggest epidural hematoma or meningioma. Lymphoma should be considered as a rare but possible diagnosis before operation. High resolution computed tomography using direct coronal imaging with and without contrast enhancement may aid in suggesting the correct preoperative diagnosis.

Intracranial vasculitis and multiple abscesses in a pregnant woman.

Cerebral vasculitis is an unusual disorder with many causes. Infectious causes of cerebral vasculitis are predominantly bacterial or viral in nature. Purulent bacterial vasculitis is most often a complication of severe bacterial meningitis. The patient is a 25-year-old African American female, 25 weeks pregnant, who presented to the neurology service after a consult and referral from an outside hospital. She had a 1-month history of right sixth nerve palsy. Initial workup included a negative lumber puncture and a noninfused magnetic resonance imaging (MRI). Three days later, the patient developed right-sided migraine headaches and right third nerve palsy. The angiogram revealed diffuse irregularity and narrowing of the petrous, cavernous, and supraclinoid portions of the internal carotid and right middle cerebral arteries. Shortly thereafter, an MRI examination revealed diffuse leptomeningeal enhancement and abscess and a right parietal subdural empyema. Infectious vasculitis secondary to purulent meningitis has a rapidly progressive course and presents with cranial nerve palsy with involvement of the cavernous sinus. Although the association of this disease with pregnancy has not been established, it should be recognized that the early imaging studies may be negative or discordant and follow-up imaging might be necessary.

Intraosseous sacral myxopapillary ependymoma and the differential diagnosis of sacral tumors.

Although involvement of other regions of the spinal cord and brain stem is seen, myxopapillary ependymoma is most commonly found at the filum terminale or cauda equina. Less commonly, myxopapillary ependymoma may occur outside the central nervous system from direct metastatic extension of an intrathecal tumor, and rarely it may present as a primary tumor outside the thecal sac. The authors present a case of primary sacral myxopapillary ependymoma, which was first diagnosed as a chordoma. They then discuss the magnetic resonance imaging findings of this and other sacral tumors. Myxopapillary ependymoma should be considered in the differential diagnosis for a primary expansile sacral mass along with other lesions such as chordoma, aneurysmal bone cyst, and giant cell tumor.

Late temporal lobe necrosis in patients with nasopharyngeal carcinoma: evaluation with combined multi-section diffusion weighted and perfusion weighted MR imaging.

Late temporal lobe necrosis is a well-known and serious complication in patients with nasopharyngeal carcinoma (NPC) following radiotherapy. Owing to the close proximity to the skull base, the medial temporal lobes are inevitably included in the target volume of irradiation. Patients with NPC provide a unique opportunity in study of delay radiation effect in normal human brain. The objective of this study was to evaluate late temporal lobe radiation injury by combined multi-section diffusion weighted and perfusion weighted MR imaging. We prospectively studied 16 patients with typical clinical symptoms of late temporal lobe necrosis or other abnormalities in the temporal lobes incidentally detected by conventional MR imaging. All patients had a previous history of radiotherapy for histologically proven NPC. Conventional T1- and T2-weighted images, fast gradient echo with echo-planar diffusion-weighted and perfusion-weighted MR imaging were performed. Apparent diffusion coefficient (ADC) map and relative cerebral blood volume (rCBV) map were computed via commercially available software. MR diffusion and perfusion images were then analyzed and graded by two independent observers with focusing on the diffusion and perfusion mismatch. The temporal lobe lesions displayed marked high diffusion on the ADC map. The rCBV map also revealed marked hypoperfusion in these temporal lobe lesions in all patients. The areas of abnormality on the rCBV map were significantly larger than the lesions on the ADC map in 14 patients (observer 1) and 13 patients (observer 2). Since late temporal lobe necrosis is probably caused by damage of the endothelium of vessels and ischemia, perfusion and diffusion mismatch might imply injured tissue but potentially salvageable brain tissue. A mismatch may be potentially used to predict the response to treatment in-patients with late temporal lobe necrosis.

Neuroimaging of AIDS. I. Central nervous system toxoplasmosis.

Toxoplasmosis is the most common cerebral mass lesion encountered in HIV-positive patients. Previously uncommon, this disease has increased markedly since the AIDS epidemic. There are occasionally unusual appearances of central nervous system toxoplasmosis that make diagnosis by standard imaging techniques difficult or impossible. More recently, MR spectroscopy has increased the ability to differentiate between various central nervous system lesions.

Epidural hematomas of the posterior fossa.

The authors report four cases of epidural hematoma of the posterior fossa. The presenting signs and symptoms are discussed. Emphasis is placed on the need for early recognition and treatment and the fact that concomitant supratentorial lesions may be present. The radiologic findings are discussed, and special note is made of the value of computed tomographic (CT) scanning. Suboccipital craniectomy may result in complete recovery, even in moribund cases, once the lision is suspected and treated.

Sphenoid sinus mucoceles presenting as intracranial masses on computed tomography.

Two cases of mucocele of the sphenoid sinus that presented as sellar and parasellar masses on computed tomography (CT) are presented. One mucocele was isodense while the other was hyperdense (100 Hounsfield units). Neither lesion demonstrated contrast enhancement. By delineating the total extent of the lesions, CT facilitated pre-operative diagnosis and surgical management.

MR imaging of acute transverse myelitis (myelopathy).

The purpose of our study was to review the MR characteristics of acute transverse myelitis (ATM) retrospectively and to review the literature. The subjects were 26 patients (two males, 24 females). MR examinations were carried out using a 1.5 Tesla scanner. MR imaging in eight of 16 lesions in nine subjects with preexisting MS showed multiple areas of increased signal intensity on T2-weighted sagittal images, and 11 lesions had no cord swelling. Twelve of 16 lesions showed heterogeneous enhancement. MR imaging in 10 of 13 lesions in 12 subjects with preexisting HTLV-1 infection, mycoplasma pneumonia infection, hepatitis B vaccinations, and uncertain etiologies revealed fusiform increased signal intensity areas on T2-weighted sagittal images and cord swelling. Seven of 11 lesions in the patients who underwent injection of contrast medium showed heterogeneous enhancement, whereas others showed no enhancement. MR examination is recommended for the evaluation of ATM.

The distribution of nasal erectile mucosa as visualized by magnetic resonance imaging.

We analyzed the distribution of nasal erectile tissue by reviewing five sets of magnetic resonance imaging scans that were obtained pre- and post-decongestion. We found that cavernous tissues were located at three sites: the inferior turbinate, the middle turbinate, and the nasal septum. This study reaffirms the findings of previous studies that were performed with other modalities such as computed tomography scanning and cadaver dissections.

Syringomyelia.

Syringomyelia is not a single disease, but rather a descriptive term for any fluid cavity in the spinal cord. Regardless of the underlying etiology, the signs and symptoms of syringomyelia are related to the location, size, and extent of the cavity. With the advent of magnetic resonance imaging (MRI) and improved surgical procedures for decompression of the cavity, syringomyelia is an increasingly recognized cause of disability and even death in patients with clinical signs and symptoms of central spinal cord lesions. In this review, the etiology, pathophysiology, imaging, and treatment will be concisely discussed.