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Biomedical subjects

L Kaufman

Publications and source records attributed to L Kaufman.

At least 361 records · Page 20Linked to original sources
PubMed1983

The potential impact of nuclear magnetic resonance imaging on cardiovascular diagnosis.

Nuclear magnetic resonance (NMR) is used to generate cross-sectional images of the human body that show excellent anatomic and functional definition. The NMR imaging process involves interactions between electromagnetic fields and the hydrogen nuclei being imaged. These interactions occur on time scales of milliseconds to seconds. Consequently, the motion of these nuclei, for instance, when carried by blood, produces distinct signatures that are used to assess flow in major vessels. Myocardial dyskinesis also produces visible effects. Because of these effects, NMR imaging may be a safe and effective tool in the diagnosis and assessment of cardiovascular disease.

Blood Flow Velocity↗
PubMed1983

NMR demonstration of cerebral abnormalities: comparison with CT.

Sixty-eight patients with a wide spectrum of brain pathology were imaged with both computed tomography (CT) using a G.E. 8800 scanner and nuclear magnetic resonance (NMR) imaging with a 3.5 kG prototype device. NMR was more advantageous in the detection and/or characterization of pathology in 20 of the 68 patients, especially when demyelination was part of the disease process or when the lesion was obscured on CT by beam-hardening artifact. Punctate foci of calcification identified on CT were not detected on NMR, but larger calcifications were seen. NMR was sensitive to detection of both normal and abnormal vascular structures. The ability of NMR to differentiate among different pathologic entities remains to be fully evaluated. NMR currently complements CT in the evaluation of many disease entities and may actually supplant CT in some. The full future potential of NMR and its role with respect to CT has only begun to be elucidated.

Adolescent↗
PubMed1983

Nuclear magnetic resonance imaging of vasculature of abdominal viscera: normal and pathologic features.

Nuclear magnetic resonance (NMR) imaging of intraabdominal vascular anatomy and the effect of various lesions on retroperitoneal and splanchnic vessels was assessed in 67 patients and volunteers using a superconducting magnet (0.35 tesla) and the spin-echo imaging techniques. Because of the low signal generated by flowing blood in most images, blood vessels, including intraparenchymal vessels, were well demonstrated. Clear delineation of the splenic vein facilitated visualization of the normal pancreas and pancreatic masses. Variation in the size and shape of the inferior vena cava and portal venous system reflected constricting and mass lesions. Preliminary observations from this initial experience suggest conspicuity of splanchnic vessels out of proportion to the current spatial resolution of NMR imaging due to the marked natural contrast between flowing blood and solid organs.

Abdomen↗
PubMed1983

Magnetic resonance imaging of the spinal cord and canal: potentials and limitations.

Preliminary experience with magnetic resonance imaging (MRI) of the spinal cord and canal in 17 patients indicates considerable promise in the diagnosis of neoplastic, degenerative, and congenital lesions. The ability to image the cord directly rather than indirectly as in myelography, the absence of bone artifact as in computed tomography, and the multiplanar capabilities indicate that MRI will be the procedure of choice in the examination of the spinal cord. Current limitations include partial-volume effects due to slice thickness and the inability to perform contiguous sections when using multiplanar techniques. The relative increase in signal from cerebrospinal fluid with long TR and TE sequences in spin-echo imaging may result in less sensitivity than in the brain for detection of cord edema and/or infarction.

Humans↗
PubMed1983

National case-control study of Kaposi's sarcoma and Pneumocystis carinii pneumonia in homosexual men: Part 2. Laboratory results.

The Centers for Disease Control conducted a case-control study to investigate an outbreak of Kaposi's sarcoma and Pneumocystis carinii pneumonia in homosexual men. The occurrence of these diseases was found to be associated with certain aspects of lifestyle, including a greater number of male sex partners per year, exposure to feces during sex, history of syphilis and non-B hepatitis, treatment for enteric parasites, and use of various illicit substances. Laboratory studies reflected both this lifestyle and the probable underlying cause of the Kaposi's sarcoma and P. carinii pneumonia--cellular immune deficiency. Patients were found to have lymphopenia, specifically a deficiency of the T-helper subpopulation, resulting in a reversal of the T-helper to T-suppressor ratio. Levels of IgG and IgA were increased. When compared with controls, patients were also found to have significantly higher titers of antibody to Epstein-Barr virus and cytomegalovirus, a higher prevalence of antibody to hepatitis A virus and Treponema pallidum, a lower prevalence of antibody to varicella zoster virus, and a higher frequency of isolation of cytomegalovirus.

Acquired Immunodeficiency Syndrome↗
PubMed1983

Cardiovascular imaging with nuclear magnetic resonance.

This article provides some examples of what the previous article outlined. The sections on Image Display and Myocardial Characterization contain numerous illustrations of gating, cross-sectional images, flow signals, and ischemic injury. The possibility of metabolic imaging with NMR and quantitating blood flow is also considered.

Aorta, Abdominal↗
PubMed1983

Active anterior rhinomanometry in pre- and postoperative evaluation, use of Broms' mathematical model.

The authors studied the value of the Broms' mathematical model for active anterior rhinomanometry in a pathological population. They compared all different variables of a pathological group with a normal group and found significant differences for v0, v2 and R. There existed no difference between the means of v0 before and after surgery. There existed, however, a strongly positive correlation between the expiration and inspiration value. The influence of surgery was always significant for the variables v1, v2, v3 and R. Furthermore, the absolute deviation between the computed values and the recorded values tended to be very small. So, the authors concluded that rhinomanometry is a valuable aid in judging pre- and postoperative results.

Adolescent↗
PubMed1983

Nuclear magnetic resonance imaging clinical experience in San Francisco.

NMR is a new extremely promising imaging modality that combines the advantages of X-ray computed tomography by giving high resolution tomograms, of ultrasound by allowing imaging in any desired plane without the dangers from ionizing radiation and nuclear medicine by offering information about physiology and metabolic processes. These advantages are not combined with any of the drawbacks of the other modalities, and are due to the ability of NMR to provide information from four imaging parameters: 1) H density; 2) T1--the spin lattice relaxation parameters; 3) T2--the spin-spin relaxation parameter; and 4) information about proton motion. NMR is already a useful clinical tool in the study of brain, cord, mediastinum, pelvis, and is promising in the study of heart, kidneys, adrenals, liver, pancreas, and spleen.

Abdomen↗
PubMed1983

Search for the relationship between academic performance and some psychosocial factors. The use of a structured interview.

Eight hundred and seventy-four freshmen underwent a structured interview to study the relationship of psychosocial factors to academic performance. The scores were measured using the SPSS computer package. The results demonstrate positive significant relationships between study success and sex, fulfilled study expectations, fulfilled college expectations, informal contacts with faculty members, introversion and confidence. The scores indicate negative significant relationships between study success and regular alcohol drinking, abuse of medication and some psychopathological symptoms.

Achievement↗
PubMed1983

Search for the relationship between interrupted university attendance of first year students and some psychosocial factors.

Eight hundred and seventy-four freshmen underwent a structured interview to study the relationship of some psychosocial factors to interrupted university attendance. The scores were measured using the SPSS computer package. The scores indicate negative significant relationships between interrupted university attendance and satisfactory housing, own study choice, study motivation, campus participation and irregular alcohol consumption. The results demonstrate a positive significant relationship between withdrawal and the distance from the university.

Adolescent↗
PubMed1982

[Nuclear magnetic resonance imaging. Clinical applications].

Nuclear magnetic resonance (NMR) imaging is based on selective excitation of proton magnetic properties by means of a dual magnetic field. In the human body, NMR gives sectional images which represent hydrogen atom densities in the different tissues. The first results obtained in tomography of the brain, spinal cord, intrathoracic and abdominal organs and some vessels have been remarkable. The magnetic fields ans radiofrequency waves involved appear to be harmless. NMR imaging favourably compares with X-ray computerized tomography or with ultrasonography and will no doubt be increasingly used for its special qualities.

Abdomen↗
PubMed1982

Tonotopic organization of the human auditory cortex.

Neuromagnetic measurements of responses to auditory stimuli consisting of pure tones amplitude-modulated at a low frequency have been used to deduce the location of cortical activity. The evoked field source systematically increased in depth beneath the scalp with increasing frequency of the tone. The tonotopic progression can be described as a logarithmic mapping.

Acoustic Stimulation↗
PubMed1982

Characterization of the human auditory cortex by the neuromagnetic method.

Neuromagnetic studies show that the location of cortical activity evoked by modulated tones and by click stimuli in the steady state paradigm can be determined non-invasively with a precision of a few millimeters. The progression of locations for tones of increasing frequency establish an orderly tonotopic map in which the distance along the cortex varies as the logarithm of the frequency. The active region responding to clicks lies at a position that is consistent with this map if the stimulus is characterized by the frequency of the peak of its power spectrum. A latency of about 50 ms observed for the response to clicks is in close correspondence with a strong component of the transient response to an isolated click reported in the literature. Monaural stimulation of the ear contralateral to the hemisphere being monitored produces a latency which is about 8 ms shorter than stimulation of the ipsilateral ear, in agreement with previous studies of transient responses. The amplitudes of the responses for binaurally presented clicks for sleeping subjects is substantially diminished for repetition rates above 20 Hz but is enhanced for lower rates.

Acoustic Stimulation↗
PubMed1982

Modulation transfer functions of the human visual system revealed by magnetic field measurements.

Properties of a neural source of magnetic field localized in the occipital lobe was measured in a steady-state paradigm using contrast reversing gratings. Comparisons with scalp potentials provided evidence that the evoked field was associated with intracellular currents. Its modulation transfer functions were similar to the analogous functions for the scalp potential and the detection of a grating. Moreover, the amplitude of the evoked field was linearly related to the potential amplitude and their phases were nearly identical. An analysis of the results in terms of theoretical relations between evoked field and potential led us to conclude that these two measures may yield a similar characterization of the source when one dipolar source predominantly gives rise to both measures, but they may yield complementary information when multiple sources contribute to the measures.

Evoked Potentials, Visual↗