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Biomedical subjects

W W Orrison

Publications and source records attributed to W W Orrison.

At least 55 records · Page 3Linked to original sources
PubMed1993

Magnetic source imaging: a review of the Magnes system of biomagnetic technologies incorporated.

Magnetic source imaging (MSI) is a new, noninvasive technique for defining the relationship between brain function and structure on a patient-to-patient basis. It achieves this by combining detailed neurophysiological data derived from magnetoencephalography with high-quality neuroanatomical data derived via magnetic resonance imaging. By the use of mathematical models, the spatial locations of those neurons that generate neuromagnetic signals of interest are estimated and subsequently marked on spatially aligned magnetic resonance images. There are three prominent types of clinical MSI examinations. These are: 1) functional mapping examinations in which sensory and motor functions are localized; 2) examinations of interictal epileptiform activity; and 3) examinations of abnormal low-frequency magnetic activity, which has been found to be present in a wide range of pathophysiological conditions. Functional mapping provides useful information regarding the relationship between the cortical representation of eloquent function and the location of pathological lesions that may be surgically resectable. This application is of particular utility in cases of intracortical masses that distort and obscure the local neuroanatomy. By defining the primary sites of interictal epileptiform activity, MSI examinations are useful in the surgical planning for the implantation of depth electrodes and the planning of partial lobectomies. Abnormal low-frequency magnetic activity appears to be a neurophysiological correlate of ischemic penumbra associated with stroke, neoplasms, and vascular malformations. Abnormal low-frequency magnetic activity has also been found to be present in several other conditions, including head trauma and psychiatric dysfunction, although the exact pathophysiological mechanisms are presently unclear.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Mapping↗
PubMed1992

Calcification of the trochlear apparatus of the orbit: CT appearance and association with diabetes and age.

OBJECTIVE: Calcification can sometimes be observed on CT scans in the region of the trochlear apparatus of the orbit, the cartilaginous structure through which the superior oblique tendon and its sheath pass. We evaluated associations of trochlear calcifications with age and diabetes. MATERIALS AND METHODS: We retrospectively reviewed CT scans of the orbit in 159 patients to identify the presence of trochlear calcifications. The presence or absence of diabetes, duration of diabetes, type of therapy, and presence or absence of neuropathy were determined from medical charts of 139 patients. We calculated the odds ratio of detecting a trochlear calcification and used logistic regression to evaluate the associations of age, sex, and diabetes with trochlear calcification. RESULTS: Trochlear calcifications were present in seven of the 24 diabetic patients and in 10 of the 115 nondiabetic patients. The odds ratio for detecting trochlear calcifications in diabetic vs nondiabetic patients was 4.3 (p < .01). Logistic regression showed univariate associations with trochlear calcification for both increasing age (p < .001) and diabetes mellitus (p < .01). The effect of diabetes on the prevalence of trochlear calcifications was seen predominantly in those less than 40 years old (odds ratio = 24.0, p = .014). Sex, duration of diabetes, insulin dependence, and neuropathy were not significantly associated with an increase in trochlear calcifications. CONCLUSION: The results show that a trochlear calcification seen on CT is a benign condition that may serve as a marker for diabetes in young patients. Trochlear calcifications are observed frequently (25-30%) in persons more than 50 years old. When it is present in patients younger than 40 years, it is strongly associated with diabetes.

Adolescent↗
PubMed1991

Magnetic resonance imaging in minor head injury.

STUDY OBJECTIVES: To investigate the role of cranial magnetic resonance (MR) imaging in evaluating patients discharged from the emergency department after minor head injury. DESIGN: A prospective blinded cohort study. SETTING: University hospital ED. TYPE OF PARTICIPANTS: Fifty-eight patients with minor head injury who were discharged from the ED with written head injury instructions. Patients admitted to the hospital were excluded. INTERVENTIONS: Ultra-low-field cranial MR scans were performed on patients within 24 hours of discharge. Scans were read blindly by two radiologists. MEASUREMENTS AND MAIN RESULTS: Fisher's exact test was used to compare symptoms in patients with abnormal and normal MR scans. There was no significant difference in symptoms between patients with abnormal and those with normal scans (P greater than .10). The proportion of abnormal MR scans was analyzed using the binomial distribution. Six of the 58 patients (10.3%) had traumatic intracranial abnormalities (proportion, 0.103; SD, 0.04; 95% CI, 0.04-0.21). Three had cortical contusions, and three had small subdural hematomas. Two of the six patients with abnormal MR scans, both with small subdural hematomas, had normal computed tomography scans. CONCLUSION: Ten percent of patients discharged from the ED after minor head injury had abnormal ultra-low-field cranial MR scans. Additional research is needed to establish the clinical importance of this unexpected observation.

Adolescent↗
PubMed1991

Validation of quantification of breast implant capsule surface area and volume using magnetic resonance imaging.

Capsular contracture has been among the most frequent and frustrating complications of augmentation and reconstructive mammoplasty with silicone breast implants. Experimental evaluation of methods designed to modify the capsule has been limited by the lack of an effective method for quantification of contracture. It has been suggested that measurement of capsule surface area would be the most direct way to quantify capsular contracture. A method using magnetic resonance imaging for calculation of implant surface area is demonstrated; validation of this method using silicone phantoms with geometrically known surface areas is presented. The surface areas of two implants were also measured in a human subject; this represents the first reported measurement of an implant capsule surface area in vivo. Calculation of surface area according to the tiling method appears to be valid, whereas the circumference method consistently underestimates capsule surface area. Although clinical correlation has not been proved, it is hoped that further experimental studies of capsular contracture will incorporate this quantitative method.

Breast↗
PubMed1991

Magnetic resonance imaging of severely disturbed children--a preliminary study.

This study investigates the relationship between brain pathology and psychiatric disturbance in 37 psychiatric inpatients between 5 and 14 years of age referred for magnetic resonance imaging (MRI). Of 37 images, 13 were categorized as abnormal by neuroradiologists who were blind to the diagnoses of subjects. Three of six children with schizophrenia-related diagnoses had abnormal scans. In contrast, only one of 15 children with a primary disruptive behavior disorder diagnosis had an abnormal magnetic resonance image. A greater proportion of children with schizophrenia spectrum diagnoses had greater left than right frontal horns of the lateral ventricles than children with other diagnoses.

Adolescent↗
PubMed1991

Magnetic resonance imaging for stenosis and subluxation in Klippel-Feil syndrome.

Magnetic resonance imaging and radiographs in neutral flexion and extension were used to evaluate 20 pediatric Klippel-Feil patients for subluxation and stenosis. Radiographs showed subluxation of 5 mm or greater in 5 (25%) of the 20 patients for an incidence of 25%. Magnetic resonance imaging documented stenosis of 9 mm or less below C1 in 5 (25%) of the 20 patients. Cord abnormalities were discovered in three (12%) of the patients: one hydromyelia with Arnold-Chiari I malformation and diplomyelia in two. The incidence of stenosis and subluxation was higher than the literature would suggest in this pediatric population. Magnetic resonance imaging is a useful tool and should be used to evaluate Klippel-Feil patients for cord abnormalities and cord compression.

Adolescent↗
PubMed1991

Ocular hazard of metallic fragments during MR imaging at 0.06 T.

The hazard of magnetic resonance (MR) imaging at low field strength (0.06 T) was examined by using both in vitro and in vivo animal experiments. Ferromagnetic fragments, 0.25-2.2 mm in diameter, were placed in vitreous humor obtained from excised cow eyes and in rabbit eyes. The magnetic field strength at which motion occurred was measured for each fragment size. Two types of motion, rotation and translation, were observed. The authors found that fragments that could not be seen on plain radiographs did not appear to move enough to be a significant ocular hazard during MR imaging at a field strength of 0.06 T.

Animals↗
PubMed1991

Comparison of CT, low-field-strength MR imaging, and high-field-strength MR imaging. Work in progress.

To assess objectively the sensitivity and specificity of low-field-strength (0.064 T) magnetic resonance (MR) imaging, a prospective blind study of 280 examinations was performed to compare low-field-strength MR imaging with computed tomography (CT) and with high-field-strength (1.5-T) MR imaging of the cranium. The sensitivity (defined as the true-positive rate) with high-field MR imaging was superior to that with low-field MR imaging and CT in helping detect overall abnormalities. Sensitivities were generally similar over a broad range of specific cranial central nervous system diseases. Low-field and high-field MR imaging were equivalent in the blind diagnoses of neoplasms and white matter disease, whereas low-field MR and CT were equivalent in the blind diagnoses of contusion, subdural and epidural hematoma, sinus disease, normality, and abnormality. The specificities with low-field MR imaging and CT were substantially better than those with high-field MR imaging.

Brain↗
PubMed1990

Neoplastic angioendotheliomatosis.

A 60-year-old white man presented with aphasia, seizures, paraparesis, and incontinence. His serologic and hematologic profiles were unremarkable. His cerebrospinal fluid showed pleocytosis, increased daily central nervous system IgG synthesis, increased myelin basic protein, and negative cytology and cultures. Cerebral computed tomography exhibited multiple areas of hypodensity but spinal computed tomography and myelography showed no abnormalities. Cranial and spinal magnetic resonance imaging revealed areas of increased signal on T2-weighted images. The use of gadolinium-pentetic acid on T1-weighted images delineated smaller areas of cortical enhancement with surrounding rim of decreased signal. Brain biopsy showed intravascular malignant cells positive for leukocyte common antigen and B-cell markers. The diagnosis was neoplastic angioendotheliomatosis (intravascular lymphomatosis). To our knowledge, this is the first report on the use of both cranial and spinal magnetic resonance imaging in this condition.

Brain↗
PubMed1990

Percutaneous choledochoscopic choledocholithotomy in Caroli's disease.

Communicating cavernous ectasia of the intrahepatic bile ducts (Caroli's disease) is frequently accompanied by calculus formation. Percutaneous choledocholithotomy was successfully performed using a choledochoscope in a young adult with multiple calculi. To our knowledge this is the first reported case of choledocholithotomy using this technique in Caroli's disease.

Adult↗
PubMed1990

Scintigraphic appearance of uncommon soft-tissue osteogenic sarcoma metastases.

The advent of improved chemotherapy has changed the natural course of osteosarcoma. The role of bone scintigraphy in the workup of metastatic osteosarcoma is being re-evaluated. Extra-osseous osteogenic sarcoma metastases, particularly pulmonary metastases, are known to accumulate bone-avid agents. In this case, there is also uptake by noncalcified metastases to the brain and to soft tissues of the leg and arm which has not been previously reported. Correlation with computed tomography and magnetic resonance imaging is made.

Adult↗
PubMed1989

Anatomic evaluation of cisternal puncture.

Cisternal puncture, although less frequently used since the advent of computed tomography and magnetic resonance imaging, is an important tool in the neurodiagnostic armamentarium. An anatomic study of cisternal puncture was conducted on fresh cadavers by direct visualization and fluoroscopic guidance of cisternal puncture. Anatomic and radiographic analyses demonstrated a dramatic dynamic anatomy of the cisternal space during cisternal puncture and indicated that "tenting" of the dura mater over the needle occurs reliably during cisternal puncture. Lateral fluoroscopy may decrease the risk of cisternal puncture by allowing visualization of needle depth in the cisternal space.

Cerebrospinal Fluid Shunts↗
PubMed1989

Arteriography with portable DSA equipment.

Fifty-one arteriograms were obtained outside of the radiology department with portable digital subtraction angiographic equipment. Thirty-five studies were performed in the emergency room, 12 in the operating room, and four in the intensive care unit. There was a significant decrease in the time interval from arrival in the emergency room to arteriogram completion for examinations performed in the emergency room with portable equipment, compared with those performed in the radiology department. One of the 51 examinations yielded questionable results and was repeated with the conventional screen-film technique. Accurate angiographic diagnoses can be obtained by means of portable equipment in a variety of hospital locations.

Angiography↗
PubMed1989

Clinical significance of MRI white matter lesions in the elderly.

The clinical relevance of white matter hyperintensities (WMH) seen on MRIs of elderly individuals is controversial. To resolve this issue, we performed MRI and neuropsychological testing on 46 healthy participants in the longitudinal Aging Process Study at the University of New Mexico. We graded the MRIs for severity of WMH using a scale tested on an elderly patient population. We found that 22% of normal subjects had moderate lesions and 9% had severe lesions. All subjects had normal neurologic examination findings and were within normal limits on a battery of neuropsychological tests. Neuropsychological performance decreased and the severity of WMH increased with age. However, when the data were corrected for age, there was no correlation between neuropsychological function and the presence of WMH. We conclude that white matter changes in the elderly by themselves are of doubtful clinical significance.

Aged↗
PubMed1988

Familial cavernous angiomas of the brain in an Hispanic family.

We found cavernous angiomas (CA) in 10 of 22 members of a large Hispanic family. The proband had seizures, and a CA was found at surgery. He and two sisters with seizures had normal angiograms, but CT or MRI showed lesions compatible with CA. Similar abnormalities were found in two cousins with seizures and 5 of 17 asymptomatic relatives studied. MRI proved to be more sensitive than CT for identifying CA. Hispanic families appear to have a predisposition for dominantly inherited CA of the brain.

Adult↗
PubMed1987

Venous air embolism.

This case report describes a new radiologic finding, that of an air-fluid level in the pulmonary artery. This is pathognomonic of venous air embolism when the patient has a chest film made in the upright position.

Catheters, Indwelling↗