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Biomedical subjects

L Kaufman

Publications and source records attributed to L Kaufman.

At least 325 records · Page 18Linked to original sources
PubMed1984

Magnetic resonance imaging of the pericardium: normal and pathologic findings.

Twenty normal subjects and ten patients with pericardial abnormalities underwent ECG-gated magnetic resonance (MR) imaging of the thorax using a 0.35-tesla superconducting system. The patients with pericardial abnormalities were also evaluated with serial chest radiographs, ultrasound, computed tomography, and/or angiography. ECG gating was necessary to identify the normal pericardium, which was visualized as a 1- to 2-mm-wide curvilinear structure of low signal intensity. Pericardial thickening in constrictive pericarditis was clearly delineated on gated MR images. Pericardial inflammation caused a marked increase in signal intensity as well as thickening of the pericardium. Pericardial effusions and pericardial adhesions were also demonstrated. A simple pericardial cyst and a complex pericardial mass were identified and differentiated from pericardial fat and diaphragmatic eventration. MR appears to be an important modality for the evaluation of pericardial disease.

Adult↗
PubMed1984

Magnetic resonance imaging: effects of magnetic field strength.

Magnetic resonance images of the head, abdomen, and pelvis of normal adult men were obtained using varying magnetic field strength, and measurements of T1 and T2 relaxations and of signal-to-noise (SN) ratios were determined. The T1 relaxation of gray matter, white matter, and muscle increases and T2 decreases with field strength, while T1 of fat remains relatively constant and T2 increases. As a consequence, for any one spin echo sequence, gray/white matter contrast decreases and muscle/fat contrast increases with field. SN levels rise rapidly up to 3.0 kgauss and then change more slowly, actually dropping for muscle. The optimum field for magnetic resonance imaging depends on tissue type, body part, and imaging sequence, so that it does not have a unique value. Magnetic resonance systems that operate in the 3.0-5.0 kgauss range achieve most or all of the gains that can be achieved by higher magnetic fields.

Abdomen↗
PubMed1984

Analytical tools for magnetic resonance imaging.

The response of different magnetic resonance (MR) techniques to tissue parameters - T1, T2, and N(H) - is a determinant of clinical efficacy. The large possible number of imaging techniques and range of variable parameters for each make it difficult to perform exhaustive evaluations in a single patient or even in animal models. In addition, changes in operating magnetic field strength change the relaxation times sufficiently so that the efficacy of a technique at a given field does not imply similar results at another field value. Tools are demonstrated that permit the evaluation of the efficacy of any model of response to tissue parameters, and also allow the investigation of the effects of changing magnetic field. Global maps of signal difference between tissues as well as calculated images are obtainable from a minimally sufficient data set. These tools serve as an important adjunct to experimental work.

Electron Spin Resonance Spectroscopy↗
PubMed1984

Magnetic resonance imaging strategies for heart studies.

Given a suitable trigger signal, cardiac synchronized magnetic resonance (MR) imaging is simple to implement; however, single section techniques are not efficacious, especially when the heart rate sets the repetition interval. We demonstrate multi-section, double, and single-echo imaging, any of which rapidly covers the cardiac volume; 3-D modes capable of achieving very thin sections; and cycled multi-section imaging capable of efficaciously providing dynamic data on heart motion. These modes form a complementary, powerful set of options for clinical work.

Heart↗
PubMed1984

Imaging by nuclear magnetic resonance in patients with chronic ischemic heart disease.

Cardiac anatomy was defined by gated nuclear magnetic resonance (NMR) imaging at a magnetic field strength of 3.5 kGauss in eight normal subjects and 10 patients with chronic myocardial infarctions. Multisectional imaging was performed with the spin-echo technique and encompassed most of the left ventricle in an imaging time of 5 to 12 min. In all subjects internal cardiac structure was well delineated without the use of any type of contrast medium. The myocardial wall-blood interface was sharply defined, resulting in visualization of trabeculations, papillary muscle, and chordal structures in both ventricles. In patients with ischemic heart disease, the extent of postinfarctional wall thinning, aneurysms, and mural thrombi were depicted on NMR images. Images obtained with the second spin-echo (delay time = 56 msec) demonstrated high signal intensity in regions of the left ventricular chamber adjacent to the site of aneurysms or infarctions; this finding suggested stasis of blood in a region of akinesis or dyskinesis. The results of this study show that gated NMR is feasible as a technique for imaging the human heart and is capable of demonstrating a variety of left ventricular abnormalities associated with chronic myocardial infarction. NMR is a completely noninvasive technique for clinical imaging of the cardiovascular system.

Adult↗
PubMed1984

Nuclear magnetic resonance: principles of blood flow imaging.

Nuclear magnetic resonance (NMR) imaging with spin-echo techniques defines vascular structures with superb anatomic detail. Contrast agents are not necessary as there is intrinsic contrast between flowing blood and the vascular wall. The signal intensity from blood within the vessel lumen varies with the sequence of gradient and radiofrequency pulses used to generate the image as well as with the velocity of blood flow. Appropriate imaging techniques can optimize anatomic detail, distinguish slow from rapidly flowing blood, and serve to identify marked impairment or complete obstruction of flow in an artery or vein. Some examples of these principles in the intracranial circulation are illustrated.

Adolescent↗
PubMed1984

Multiplane magnetic resonance imaging of the heart and major vessels: studies in normal volunteers.

The feasibility of magnetic resonance imaging for defining anatomy of internal cardiac structures and major blood vessels was assessed in 14 normal subjects. Both electrocardiogram-gated and standard spin-echo images were obtained. The R-R interval determined the pulse repetition times in gated sequences. Gated images provided better visualization of internal cardiac morphology and of upper mediastinal vessels than did nongated images. Trabecular detail and components of the mitral valve could be resolved. All segments of the left ventricular wall could be evaluated by combining axial, coronal, and sagittal images. Gated acquisition of magnetic resonance images did not increase imaging time; five transverse slices of the left ventricle were obtained in 6.0-8.5 min. The good image quality, ease of gated acquisition, large field of view, capability of direct imaging in multiple planes, and noninvasiveness of the technique suggest that it will be an important imaging method in cardiovascular disease.

Adult↗
PubMed1984

Magnetic resonance imaging of aortic disease: preliminary results.

Fourteen patients with a variety of aortic diseases were evaluated with magnetic resonance imaging (MRI). These included abdominal aortic aneurysms (eight cases), aortoiliac aneurysm (one), thoracoabdominal aneurysm (one), aortic dissections (four), and Takayasu arteritis (one). The size and extent of aneurysms, the presence of thrombus or atherosclerotic debris, the relation to renal and iliac arteries, and the effect of aneurysms on adjacent structures were readily demonstrated by MRI. The size of the residual lumen in a variety of vascular diseases and abnormal blood flow patterns could be assessed. In aortic dissection, MRI permitted identification of intimal flaps and determination of the origin of aortic branches from either of two lumina. Thickening of the wall and luminal narrowing of the aorta and arch vessels in Takayasu arteritis were clearly defined. These early results indicated that MRI achieved precise and complete assessment of a number of aortic abnormalities without the administration of any type of contrast material. Thus, early experience suggests that an important application of MRI will be as a totally noninvasive and reliable method for evaluating aortic disease.

Adult↗
PubMed1984

Enzyme immunoassay detection of IgM to galactoxylomannan of Cryptococcus neoformans.

Antibodies against the major capsular polysaccharide of Cryptococcus neoformans, glucuronoxylomannan (GXM), and a minor secreted polysaccharide, galactoxylomannan (GalXM), were surveyed by indirect enzyme immunoassay (EIA) in patients with cryptococcosis, with other mycoses, and in normal controls. Measurement of IgG levels against GalXM revealed cross reactions in candidiasis patients that were reduced by adsorption with Candida albicans cell walls. Measurement of IgM levels were subject to fewer cross reactions. The combination of adsorption with C albicans cell walls and measurement of IgM detected antibodies in 12 of 55 cryptococcosis patients. An end point equal to or greater than a titer of 1/16 excluded reactions in normals and limited cross reactivity in candidiasis patients to below 7%. This test has potential diagnostic significance in cryptococcosis patients who show no evidence of cryptococcal antigen circulating in the cerebrospinal fluid or serum. Reactions in this IgM assay were not spuriously due to rheumatoid factor. The major capsular GXM was much less serologically active and was subject to cross reactions with agents of bacterial sepsis. The specificity of the GalXM is directed mainly by the mannose and to a lesser extent by galactosyl residues.

Antibodies, Anti-Idiotypic↗
PubMed1984

Antigenic relationships among Cladosporium species of medical importance.

We analyzed the exoantigens of 54 isolates belonging to the pathogenic Cladosporium species. Cladophialophora ajelloi was found to be antigenically identical to Cladosporium carrionii. All human and cat isolates of C. bantianum and C. trichoides were found to share the same antigens. Although cross-reactions were observed among the four species of Cladosporium: C. carrionii, C. bantianum, c. herbarum, and C. cladosporioides they were identified and differentiated specifically with four monospecific factor sera obtained through absorption procedures. The exoantigen serologic procedure also permitted us to identify cultures of these four Cladosporium spp. within 8 days.

Animals↗
PubMed1984

The effect of beclomethasone dipropionate treatment on the nasal provocation test.

A total of 50 patients with hay fever of perennial rhinitis were treated for 14 days with beclomethasone dipropionate nasal spray. Dosage was one puff (50 micrograms) in each nostril four times a day to a total daily dose of 400 micrograms. Rhinomanometry was used to determine the efficacy of beclomethasone dipropionate in immediate type allergic responses provoked by a nasal challenge with either grass pollen or house dust/house mite allergen. Treatment with beclomethasone dipropionate nasal spray resulted in a significant increase in tolerance to both house dust/house mite allergen (P = 0.01) and grass pollen allergen (P = 0.005). Passive anterior rhinomanometry would seem to offer an easy suitable technique for measuring nasal resistance during nasal provocation tests.

Beclomethasone↗
PubMed1984

Dimensions of first year university student behavior.

Eight hundred and seventy-four freshmen underwent a structured interview to search for characteristics in student behavior. The scores were analysed using agglomerative and divisive hierarchical clustering methods. The results demonstrate the presence of two opposite dimensions in freshman behavior: the first referred to study involvement, the second referred to campus participation.

Female↗
PubMed1984

[The effect of swimming on the nasal passages and on tube function in children].

In two studies the authors want to confirm experimentally what is assumed in every day ENT-practice: otitis and sinusitis are not infrequent complications of swimming. The first study, involving 60 children with chronic non-specific lung diseases shows that swimming in a sea water pool increases the nasal airway resistance during two days. In the second study, performed in 32 normal children swimming in a chlorous pool, a negative relationship is found between the number of days after the swimming and the increased nasal airway resistance. Probably other factors also play a part in this phenomenon. Due to the too small number of children showing an otitis media with effusion, the influence of swimming on the function of the Eustachian tube could not be determined.

Acoustic Impedance Tests↗
PubMed1983

Exoantigen tests for the immunoidentification of fungal cultures.

Exoantigen tests for the immunoidentification of fungal pathogens are playing a new and significant role in the diagnostic laboratory. Properly performed and controlled exoantigen tests lead to rapid, accurate identification of cultures of many fungal pathogens. The tests are particularly valuable in identifying dimorphic pathogens that are difficult to convert or with atypical cultures. We review the value of exoantigen tests for identifying mycelial form fungi: Aspergillus spp. Blastomyces dermatitidis, Coccidioides immitis, Exophiala jeanselmei, Histoplasma spp., Paracoccidioides brasiliensis, Penicillium marneffei, Pseudallescheria boydii, Sporothrix schenckii, Wangiella dermatitidis and certain dermatophytes. We discuss procedures for performing the tests and sources of error.

Antigens, Fungal↗
PubMed1983

Nuclear magnetic resonance imaging of mammary adenocarcinomas in the rat.

A study of 24 rats implanted in the hind leg with mammary adenocarcinomas and five sham-implanted rats, followed from the second to the eight week postimplantation, showed nuclear magnetic resonance imaging capable of detecting all the tumors without yielding any false-positives in the control rats. The T1 relaxation time of tumors overlapped that of muscle, and the T2 times overlapped fat, but the combination was unique when comparing tumors to muscle and fat. Necrotic regions of the tumor and the bladder contents tended to have very long T1 and T2 relaxation times. The difference in relaxation time between tumors and muscle could be accounted for in terms of water content, which was approximately 8% higher for the tumors. The study corroborates data from previous studies indicating that NMR imaging is a highly sensitive modality, although T1 and T2 times are not exclusive indicators of malignancy.

Adenocarcinoma↗
PubMed1983

Nuclear magnetic resonance imaging in multiple sclerosis.

Ten patients with definite multiple sclerosis underwent hydrogen nuclear magnetic resonance imaging with a 3.5 kilogauss superconducting magnet, using the inversion recovery and spin-echo techniques of signal acquisition. Results were compared with high-resolution x-ray computed tomography. Spin-echo images demonstrated abnormal regions as areas of variably increased signal intensity. The contrast between abnormal and normal white matter improved as the intervals between sequential radiofrequency pulses and between pulse administration and signal sampling were increased. Inversion recovery images demonstrated abnormal areas as regions of decreased signal intensity but did not visualize lesions as well as spin-echo imaging. Spin-echo and inversion recovery imaging each demonstrated more extensive abnormalities than did computed tomography.

Adult↗
PubMed1983

Nuclear magnetic resonance imaging of acute myocardial infarction in dogs: alterations in magnetic relaxation times.

Nuclear magnetic resonance (NMR) imaging was used to study 24-hour-old acute myocardial infarctions in 8 dogs. Images and measurements of excised hearts were obtained in a 6.5 ml bore-resistive NMR imager (0.35 Tesla). Spin echo NMR imaging in each instance demonstrated the area of infarction as a region of increased signal intensity compared with that in normal myocardium. The T1 and T2 values of the area of infarction were greater than those of normal myocardium in all dogs. For each dog the T1 value was greater for the infarct region; however, the group mean value for T1 (ms) of the infarct region (728 +/- 94) was not significantly greater than that for the normal region (650 +/- 87). The T2 value (ms) was discriminate for all dogs, and the mean value for the infarct region (48 +/- 2) was significantly different (p less than 0.01) from the value for normal myocardium (42 +/- 1). The percent water content of the infarct (79 +/- 1%) was significantly greater (p less than 0.01) than that of normal regions (76 +/- 1%). The linear relationship between T2 value and percent water content showed a good correlation coefficient (r = 0.90; p less than 0.01). NMR imaging detects acute myocardial infarction as a positive image without contrast media. Increased signal intensity of the infarct is related to increased hydrogen density and increased T2 relaxation time.

Animals↗