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Biomedical subjects

L A Hayman

Publications and source records attributed to L A Hayman.

At least 37 records · Page 2Linked to original sources
PubMed1997

Neuro-ophthalmologic manifestations of adenoid cystic carcinoma.

Intracranial adenoid cystic carcinoma is uncommon. We report two unusual cases of intracranial adenoid cystic carcinoma. The first patient presented with a steroid-responsive optic neuropathy from an orbital mass that simulated orbital pseudotumor, and subsequently developed intracranial involvement, presumably by contiguous perineural spread. The second patient presented with proptosis of the left eye, right facial weakness and numbness, and an intracranial mass, presumably from hematogenous metastatic spread.

Adult↗
PubMed1995

MR imaging of the eyelids: normal and pathologic findings.

MR imaging is commonly used to evaluate orbital and facial soft-tissue disease. Although the eyelids are visible on these images, the radiographic appearance and the detailed anatomy of these structures has received little attention in the literature [1-4]. Anatomic correlation with MR images may be extremely helpful in the accurate interpretation and staging of eyelid malignancies and infections.

Adult↗
PubMed1995

Incidental asymptomatic orbital calcifications.

OBJECTIVE: To use modern computed tomography (CT) imaging to quantify the incidence of asymptomatic incidental orbital calcifications and describe their histological features. MATERIALS AND METHODS: One hundred orbital CT scans were reviewed. In addition, patients who had orbital calcification(s) detected on a brain CT scan were examined by the ophthalmology service. RESULTS: Of the orbital CT scans, 2% had bilateral drusen of the optic nerve head, 3% had calcified scleral plaques anterior to the medial or lateral rectus muscles, and 3% had bilateral ossification of the trochlear apparatus. Routine brain CT scans detected asymptomatic calcifications of the sclera and dura surrounding the proximal optic nerves. CONCLUSION: Incidental asymptomatic orbital calcifications are commonly encountered on modern high-resolution CT images of the brain and orbit. This article should help the clinician to confidently distinguish these densities from foreign bodies or pathological calcifications.

Adolescent↗
PubMed1994

Acute intracranial hemorrhage secondary to thrombocytopenia: CT appearances unaffected by absence of clot retraction.

PURPOSE: To describe the in vivo CT appearance of acute intracerebral blood clots formed from anemic platelet-depleted blood. METHODS: Three patients with intracerebral hemorrhage secondary only to thrombocytopenia were examined with CT within 2 1/2 hours after the onset of clinical symptoms. RESULTS: There were no unusual CT features found in the intracerebral hemorrhages of patients with only thrombocytopenia. Specifically, a hyperdense zone(s) surrounded by areas of decreased density was identified. CONCLUSION: Clot retraction (which cannot occur in patients with severe thrombocytopenia) is not necessary for the CT appearance of acute intracerebral hemorrhage.

Adult↗
PubMed1994

Sensitivity and specificity of fluid-blood levels for coagulopathy in acute intracerebral hematomas.

PURPOSE: To characterize the imaging features of intracerebral hemorrhages in coagulopathies that alter prothrombin time or partial thromboplastin time. METHODS: A fluid-blood level was defined as a horizontal interface between hypodense bloody serum layered above hyperdense settled blood. The prevalence of fluid-blood levels in acute intracerebral hemorrhages was determined on third-generation CT scans in 32 patients with elevation in prothrombin time or partial thromboplastin time. This was compared with the frequency of fluid-blood levels in 185 patients with intracerebral hemorrhage in which there was no laboratory evidence of coagulopathy. RESULTS: The probability of finding a fluid-blood level in an intracerebral hemorrhage of a patient with abnormal prothrombin time or partial thromboplastin time was 59% (sensitivity). The probability that there will be no fluid-blood level in a patient with a normal prothrombin time and partial thromboplastin time was 98% (specificity). CONCLUSION: Fluid-blood levels in acute intracerebral hemorrhage are moderately sensitive to the presence of coagulopathy (ie, abnormal prothrombin time and partial thromboplastin time) and highly specific for this condition. Thus, an intracerebral hemorrhage with a fluid-blood level should prompt a thorough search for coagulopathy because early treatment of this condition may improve the 40% mortality in these patients. Caution should be used to distinguish the horizontal interface of a fluid-blood level from a clot with a flat top. A decubitus CT is useful in these rare instances.

Aged↗
PubMed1993

Invasive pressure monitoring of patients during magnetic resonance imaging.

The purpose of this paper is to describe a system for monitoring patients who require general anaesthesia, profound sedation or intensive care while undergoing high field (> or = 1.5 T) magnetic resonance (MR) imaging. Continuous evaluation of invasive and noninvasive pressures, inspired and end-tidal respiratory gas concentrations, body temperature, heart rate, ECG and pulse oximetry were measured successfully during the MR examination. Diagnostic quality MR images were acquired on all 15 monitored patients. The calculated signal-to-noise ratios were not different between the control and monitored patients. Commonly encountered technical problems and their solutions are described. This study demonstrates that invasive monitoring can be safely performed in critically ill patients who are undergoing high field MR examinations.

Adult↗
PubMed1990

Temporal changes in the oxidation state in in vitro blood.

The rates at which the paramagnetic compounds deoxyhemoglobin (Hb) and methemoglobin (MHb) form in vivo within an area of hemorrhage are unknown. The present experiment establishes the baseline concentrations and rates of change in paramagnetic hemoglobin concentrations, as well as the pH in normal heparinized and clotted human blood maintained in vitro at 37 degrees C under anaerobic conditions over 30 hours. There was a moderate increase in Hb concentration in normal heparinized blood (average increase was 15.5%, rate = 0.50%/hour) and a slight increase in MHb concentration in the heparinized blood and clots (average increase was 1.4%, rate = 0.044%/hour). A second experiment was done to verify the activity of the RBC systems responsible for maintaining the hemoglobin molecule in the reduced state. Conversion of MHb to Hb in these samples proceeded at a rate of 5.6%/hour. In a third experiment, blood from 11 normal subjects maintained at 4 degrees C 25 degrees C was analyzed for MHb concentration over the course of 28 days. The level of MHb formation remained in the range of normal for at least 11 days in all subjects. The authors conclude that at basal conditions created in vitro, the blood levels of both Hb and MHb remain at relatively low levels. Therefore, if the accumulation of Hb and/or MHb occurs in acute in vivo hematomas it must be driven by intrinsic tissue factors.

Cerebral Hemorrhage↗
PubMed1990

Pregnancy and maternity leave: AAWR survey results.

In 1987 to obtain information regarding pregnancy and maternity leave policies in academic and private radiology departments, the American Association of Women Radiologists (AAWR) surveyed academic and private diagnostic radiology departments and academic radiation oncology departments in the United States and Canada. One hundred thirty-one diagnostic radiology departments and 30 radiation therapy departments responded to the questionnaire. Despite the increasing number of women entering the field of radiology, many departments do not have formal policies. Of those that do, there was a wide range of responses regarding details of maternity leave and duties during pregnancy. The AAWR recommends that every department develop a written pregnancy and maternity leave policy, which should be available to all current and prospective employees.

Brachytherapy↗
PubMed1989

Pathophysiology of acute intracerebral and subarachnoid hemorrhage: applications to MR imaging.

In this review of the pathophysiology of acute intracerebral and subarachnoid hemorrhage, information from several disciplines is assembled to describe the bleeding process, hemostasis and coagulation, fibrinolysis, erythrocyte lysis, phagocytosis, and changes in the state of hemoglobin. The impact of these pathophysiologic processes upon MR imaging, CT, and angiography is noted.

Angiography↗
PubMed1988

T2 effect of hemoglobin concentration: assessment with in vitro MR spectroscopy.

T2 values were measured at 0.23 and 4.7 T for deoxygenated blood samples (43%-73% O2 saturation) with hematocrits of 18%-100%. An increase in the hematocrit produced a marked reduction in T2 at both field strengths. Cell lysis did not abolish the T2 effect at either field strength. The authors conclude that the increase in hemoglobin concentration caused by formation of a retracted clot is a cause of the hypointense appearance of acute hemorrhage compared with brain on T2-weighted clinical magnetic resonance images. This is particularly important on low-field-strength systems, which are not sensitive to the T2 shortening effects of paramagnetic intracellular deoxyhemoglobin.

Animals↗
PubMed1987

White-matter lesions in MR imaging of clinically healthy brains of elderly subjects: possible pathologic basis.

Patchy white-matter lesions occur in the magnetic resonance (MR) imaging brain studies of 20%-30% of neurologically healthy elderly subjects. To determine the frequency of histologically verifiable white-matter lesions at autopsy in such subjects the authors examined serial, microscopic, whole brain sections from 15 clinically healthy subjects aged 52-72 years. Small white-matter lesions were found in 12. In these 12, zones of atrophic perivascular demyelination were present in eight brains. These are not the familiar thrombotic, embolic, or ischemic vascular lesions that produce acute necrosis. This mild vascular insufficiency produces atrophy, which has been recognized in the pathology literature but whose clinical significance remains unknown. Other lesions seen were small vascular malformations in the centrum ovale in four brains, diverticula of the lateral ventricle extending into the white matter in three, and an isolated central white-matter infarction in one. All of these lesions are probably the basis of the patchy white-matter lesions seen on MR imaging studies in the neurologically healthy elderly population.

Aged↗
PubMed1984

Prophylactic diazepam in prevention of contrast media-associated seizures in glioma patients undergoing cerebral computed tomography.

Five milligrams of intravenous diazepam given prior to contrast media injection statistically significantly reduced the incidence of contrast media-associated seizures from 16% to 2% in a prospective, randomized series of glioma patients. Factors related to increased risk of contrast media-associated seizures are (1) prior seizure history due to glioma and/or prior contrast media and (2) prior or concurrent brain antineoplastic therapy. Factors not related to an increased risk of contrast media-associated seizures are (1) contrast media dosage, (2) type or grade of glioma, and (3) computerized tomographic appearance of the glioma. Theories regarding the etiology of contrast media-associated seizures are discussed.

Adolescent↗
PubMed1984

Myocardial ischemia during intravenous DSA in patients with cardiac disease.

A prospective study was performed for 48 patients who had histories of angina and were referred for digital subtraction angiography (DSA). Cardiac disease was graded according to the American Heart Association (AHA) functional classification system. Each patient received 2-5 injections of 40-ml diatrizoate meglumine and diatrizoate sodium (Renografin-76, Angiovist-370, or MD-76) at 15 ml per second in the superior vena cava. Of the 28 patients in functional Classes I or II (no or slight limitation of activity), 11% had angina and 32% had definite ischemic ECG changes after the DSA injections. Of the 19 patients in functional Class III (marked limitation of activity), 63% had angina, and 58% had definite ischemic ECG changes after the injections. One patient in functional Class IV (total disability) developed ventricular fibrillation after the second injection. These observed cardiac effects following bolus injections of hypertonic ionic contrast media indicate that special precautions are necessary when performing intravenous DSA examinations on this group of high risk patients.

Aged↗
PubMed1984

Chordomas: their CT appearance in the cervical, thoracic and lumbar spine.

We reviewed 25 CT scans of 21 patients who had chordomas in the cervical, thoracic, or lumbar spine. Nine patients were studied at the time of initial presentation and 12 after tumor recurrence. All scans showed vertebral body destruction coupled with an associated soft tissue mass located anteriorly or laterally. Additional CT findings included septated areas of low attenuation within the tumor, amorphous soft tissue calcification, tumor extension into the spinal canal, disk space involvement, and contrast enhancement.

Adolescent↗