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Biomedical subjects

R G Ramsey

Publications and source records attributed to R G Ramsey.

At least 19 recordsLinked to original sources
PubMed2001

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.

Adult↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Adult↗
PubMed2000

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.

Adult↗
PubMed1999

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.

Adult↗
PubMed1997

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.

Brain↗
PubMed1997

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.

AIDS-Related Opportunistic Infections↗
PubMed1997

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.

Artifacts↗
PubMed1996

Neuroradiology.

Explore the source record for details and available documents.

Humans↗
PubMed1994

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.

Adolescent↗
PubMed1992

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.

Brain↗
PubMed1990

The pattern of vertebral involvement in metastatic vertebral breast cancer.

The spine is a common site of bony metastasis. To date, studies have not identified the initial site and pattern of vertebral metastasis in a homogeneous group of patients. Twenty-seven magnetic resonance imaging studies performed on 25 patients with metastatic vertebral breast cancer were reviewed retrospectively. The location and extent of metastatic vertebral involvement were determined. The vertebral body is the most frequent initial site of metastatic seeding. Although radiographically an absent pedicle is often the first sign of metastatic disease, involvement of the pedicle is by direct extension from either the vertebral body or the posterior elements and is therefore a late occurrence in the disease process.

Breast Neoplasms↗
PubMed1988

CNS complications of AIDS: CT and MR findings.

AIDS is now a common disease, seen daily in large metropolitan medical centers. Neuroimaging techniques such as CT and MR are critical to the detection and diagnosis of CNS complications. Intracerebral infections are common. These infections frequently are caused by opportunistic organisms; less commonly, they are bacterial infections. The cranial imaging features on CT and MR are not pathognomonic, but their distribution or appearance (e.g., asymmetric target lesions of toxoplasmosis) may have predictive value in a known AIDS patient. The superior contrast resolution of MR makes it a more sensitive cross-sectional imaging tool for evaluating intracerebral abnormalities associated with a variety of infectious processes. Differential diagnoses still include metastatic disease, lymphoma, and infarcts. When MR is used as the initial cross-sectional imaging study, contrast-enhanced CT may still be necessary to further characterize a lesion. Currently, more experience exists with CT for follow-up of the AIDS patient with CNS manifestations. MR, particularly with gadolinium-DTPA as a contrast medium, will probably become the imaging method of choice.

Acquired Immunodeficiency Syndrome↗
PubMed1987

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.

Adult↗