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.

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.

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.

Use of three-dimensional spiral computed tomography imaging for staging and surgical planning of head and neck cancer.

We compare four different three-dimensional (3D) reconstruction methods of spiral computed tomography (CT) data for head and neck cancer to establish the method best suited for specific uses, eg, staging of lymph nodes and viewing of spatial relationships between the tumor, fascial spaces, adjacent soft tissues, and others structures. We evaluated a series of 10 patients (six men and four women), aged 32 to 60 years. Of these, five were histologically diagnosed with squamous cell carcinoma, two with lymphoma, one with thyroid cancer, one with Kikuchi's disease or necrotizing lymphadenitis, and one with esthesioneuroblastoma. All scans were obtained using high-resolution spiral CT (General Electric Medical Systems, Milwaukee, WI). The collimations used were 3 mm and 5 mm, matrix 512 x 512, and reconstruction interval not more than 3 mm. Scanning was performed from the skull base to the aortic arch. Iodinated contrast medium was injected so that the blood vessels were clearly differentiated from nodes. Different techniques of three-dimensional reconstruction were employed, including shaded surface display (SSD), multiplanar reconstructions (MPR), maximum intensity projection (MIP), 3D volume rendering (VR), and combined techniques. The reconstructions were performed in a variety of planes, including sagittal, coronal, and oblique views. In our series of selected patients, the technique of 3D VR showed potential advantages over other techniques. The MIP technique was useful in analyzing the patency of vessels and to exclude thrombus, compression, or displacement by tumor. The use of combined techniques such as SSD and MPR, accurately demonstrated the levels of lymph nodes and the relationship between the tumor projection of interest and various anatomic structures. In conclusion, 3D reconstruction of CT data is useful in the localization and staging of neck tumors and assists in surgical planning and radiation treatment.

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.

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.

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.

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.

Multiple haemorrhagic brain metastases from papillary thyroid cancer.

We report a 40-year-old woman, who initially developed cerebellar symptoms, with multiple hemorrhagic brain metastases from a papillary thyroid cancer. Intracranial masses gave heterogeneous high signal on T1-weighted and T2-weighted images, hemosiderin rims on the latter. Some of the tumors showed contrast enhancement. Metastatic thyroid cancer is a consideration in a patient with multiple hemorrhagic masses.

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.

MRI of dumbbell-shaped spinal tumors.

PURPOSE: The purpose of our study is to review the clinical features and MR findings in patients with dumbbell-shaped spinal tumors that affect the intervertebral foramen. METHOD: Two radiologists retrospectively evaluated a total of 19 tumors from the period 1989-1994 that exhibited dumbbell configuration. These included 11 benign tumors, including 9 neurogenic ones, and 8 malignant tumors. RESULTS: The time between onset of symptoms and admission was shorter in patients with malignant tumors (mean 3.9 months) than in patients with benign tumors (mean 41.1 months). There was a statistically significant difference (p < 0.05) in the short/long axis ratios (minimum tumor diameter divided by maximum tumor diameter) in the vertebral canal components between benign and malignant tumors. All malignant tumors in this study were extradural and paraspinal type (p < 0.05). Most benign tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05). Many neurogenic tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05> Many neurogenic tumors had cystic lesions (77.8%) and a string-of-beads structure (44.4%). Those tumors that surrounded the thecal sac in the vertebral canal and whose adjacent vertebral bodies had abnormal signal intensities were infiltrating and malignant. CONCLUSION: There are many kinds of dumbbell-shaped spinal tumors other than neurogenic ones. MRI is useful in diagnosing dumbbell-shaped spinal tumors, especially those of neurogenic origin, and aids in distinguishing benign from malignant tumors.

Pachygyria in a neonate with prenatal cocaine exposure: MR features.

Clinical and MR findings of a neonate with diffuse severe pachygyria and prenatal exposure to cocaine are presented. The teratogenicity of cocaine is reviewed.

Plasma magnesium levels in a population of psychiatric patients: correlations with symptoms.

Plasma magnesium levels were tested in a group of 155 psychiatric in-patients with a variety of diagnoses and were correlated with the severity of their symptoms. We hypothesized that lower Mg levels would correlate with a higher degree of anxiety, tiredness and other symptoms characteristic of Mg deficiency. No such correlations were observed. However, Mg levels varied widely, with 22.4% below, and 10.4% above the normal range. There was a strong association for more disturbed and excitable patients to have abnormal (either high or low) levels. We speculate that more disturbed patients might have some abnormality of Mg metabolism with possible therapeutic implications.

CNS complications of cocaine abuse: prevalence, pathophysiology, and neuroradiology.

The United States is facing an epidemic of cocaine use by adolescents and young adults from all socioeconomic backgrounds. Epidemiologic data suggest that the use of the drug continues to increase on a year-by-year basis. This is a serious public health problem because cocaine is highly addictive and is associated with a variety of serious complications. In the CNS, these include stroke, intracerebral hemorrhage, vascular spasm, and possibly vasculitis. Seizures and sudden death have been reported. Cocaine use during pregnancy may be associated with fetal hypoxia, intracerebral hemorrhage, and possibly congenital malformations in the neonate. Many of these complications have been recognized only in the last 5-10 years. For example, ischemic changes in the brains of chronic cocaine abusers have been reported only recently. Because even further increases in cocaine use are predicted by drug enforcement officials, it is expected that radiologists will encounter its complications more frequently in the future. Therefore, radiologists should become familiar with the radiologic manifestations of the drug's effects. This article describes the drug's pathophysiology and complications and discusses the evolving role of imaging procedures.