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Biomedical subjects

L Kaufman

Publications and source records attributed to L Kaufman.

At least 217 records · Page 12Linked to original sources
PubMed1989

Measuring signal-to-noise ratios in MR imaging.

The signal-to-noise ratio (S/N) in magnetic resonance imagining is one of the variables that must be measured when comparing the relative performance of different techniques. Although various investigators and official groups have proposed different methods for measuring S/N, these are generally not practical for use by a physician working in a clinical situation. The authors present a simple method that should serve for estimating S/N in most cases.

Magnetic Resonance Imaging↗
PubMed1989

Physics of thin-section MR imaging at low field strength.

Thin-section magnetic resonance imaging at low field strengths requires analysis of the relative merits of data collection techniques for direct three-dimensional versus multisection two-dimensional imaging. This analysis was done with specific emphasis on shortened relaxation times and the use of reduced magnetic field gradients. Three-dimensional Fourier transform techniques can provide thin-section images of good diagnostic quality when combined with partial flip-angle gradient-reversal techniques.

Humans↗
PubMed1989

Monitoring of bone mineral content in patients on regular hemodialysis.

Bone mineral content (BMC) was measured at the lumbar spine region by means of dual photon absorptiometry over a 3-year period in 20 patients on regular hemodialysis (RHD). Baseline mean BMC at the start of the monitoring was significantly decreased to 82.64% of predicted value (p less than 0.05). During a 3-year follow-up mean BMC rose significantly to 90.61% (p less than 0.05). Six patients received vitamin D supplements. Analysis of the data showed that rise of BMC was similar whether vitamin D was given or not. Our data suggest that (1) RHD inhibits bone loss at the lumbar spine level that occurred mainly before active uremia treatment and (2) the increment of BMC observed in this study can be attributed to the different site of measurement, the inaccuracy of the measurements by interference with soft tissue calcifications and the dialysis conditions.

Biomarkers↗
PubMed1989

Gauging MRI's value.

Explore the source record for details and available documents.

Hospital Departments↗
PubMed1989

Exoantigen tests for the rapid and specific identification of Apophysomyces elegans and Saksenaea vasiformis.

Apophysomyces elegans and Saksenaea vasiformis frequently fail to sporulate on routine media used in clinical laboratories, thus delaying or preventing their specific identification. We have developed exoantigen test reagents capable of identifying non-sporulating isolates of A. elegans and S. vasiformis. A reagent containing three specific A. elegans precipitins was produced when A. elegans antiserum was absorbed with S. vasiformis. Antigenic analyses showed that at least two serotypes of S. vasiformis exist. Only six of 10 S. vasiformis isolates studied produced bands of identity with S. vasiformis (B-2190) (serotype 1) antiserum absorbed with S. vasiformis (B-2189) (serotype 2) antigens. The remaining four isolates, however, produced bands of identity with S. vasiformis B-2189 antiserum absorbed with B-2190 antigens. Antigenic differences among the isolates of the two groups could be correlated to some extent with the morphologic differences observed, especially with respect to the size of the sporangia and sporangiospores.

Antigenic Variation↗
PubMed1989

Incidence and etiology of rhinosinusitis in children.

The authors discuss the incidence of chronic rhinosinusitis in children. From the study of 196 CT-scans, there follows that as well the ethmoidal as the maxillary sinuses are involved in the young child. In older children, however, the incidence of maxillary sinusitis is more frequent. The etiology of chronic rhinosinusitis is discussed stressing the importance of general factors such as environmental factors, congenital and acquired abnormalities and the influence of drugs, as well as of local factors such as again environmental factors, malformations, and upper respiratory infections. Most of these factors are discussed following personal studies.

Adolescent↗
PubMed1989

Accessible magnetic resonance imaging.

The cost of magnetic resonance imaging (MRI) is driven by magnetic field strength. Misperceptions as to the impact of field strength on performance have led to systems that are more expensive than they need to be. Careful analysis of all the factors that affect diagnostic quality lead to the conclusion that field strength per se is not a strong determinant of system performance. Freed from the constraints imposed by high-field operation, it is possible to exploit a varied set of opportunities afforded by low-field operation. In addition to lower costs and easier siting, we can take advantage of shortened T1 times, higher contrast, reduced sensitivity to motion, and reduced radiofrequency power deposition. These conceptual advantages can be made to coalesce onto practical imaging systems. We describe a low-cost MRI system that utilizes a permanent magnet of open design. Careful optimization of receiving antennas and acquisition sequences permit performance levels consistent with those needed for an effective diagnostic unit. Ancillary advantages include easy access to the patient, reduced claustrophobia, quiet and comfortable operation, and absence of a missile effect. The system can be sited in 350 sq ft and consumes a modest amount of electricity. MRI equipment of this kind can widen the population base than can access this powerful and beneficial diagnostic modality.

Costs and Cost Analysis↗
PubMed1989

Some remarks on nasal polyposis.

After a short historical and literature review the authors present their definition of nasal polyposis. The importance of CT scanning is stressed and the results of a CT-scan study of 350 patients with nasal complaints is presented. The authors discuss the incidence of sinusitis, presence of polypi and nasal anomalies in this population. Furthermore 111 biopsies of nasal polypi were studied and the cellular content, the ducts, glands, veins, aspect of the basal membrane and epithelial layer were described. As an oral ASA provocation test can be hazardous, the authors tested a nasal provocation test with acetylsalicylic acid. Although the test showed some interesting results, the reproducibility was poor. Finally the authors conclude that endoscopy and CT-scanning enable the diagnosis of nasal polyposis in an early stage of the disease.

Aspirin↗
PubMed1989

"Angiography" by magnetic resonance imaging: detailed vascular anatomy without ionizing radiation or contrast media.

Using software to transform magnetic resonance imaging (MRI) tomographic data into three-dimensional projections, we have produced "angiograms" of the abdominal aorta in 18 patients with occlusive (15) and aneurysmal (3) disease. This information may be displayed to demonstrate flow, cross-sectional diameter, or aortic surface anatomy. To test the accuracy of the MRI studies, we compared them at selected points with the transected aorta and with routine aortograms. Relative cross-sectional diameter estimated by MRI was within 15% of measured aortic diameter in 14 of the 18 vessels and enabled correct detection of thrombus in 16. We conclude that MRI may accurately image the diseased abdominal aortic wall. In addition, an angiographic display format may aid in the interpretation of these studies. Although MRI is not likely to replace aortography, it could be used adjunctively to define aortic wall thickness and the presence of thrombus.

Aged↗
PubMed1989

Identification of aortic thrombus by magnetic resonance imaging.

The unique properties of magnetic resonance imaging result in the potential to differentiate various components of the diseased arterial wall. In this article four cases are presented in which magnetic resonance imaging showed mural aortic thrombus and its anatomic relationship to the visceral and renal arteries. Once thrombus is identified and localized specific operative strategies can be undertaken to prevent recurrent embolic events and/or avoid perioperative thromboembolic complications.

Aged↗
PubMed1989

Recurrent polyposis nasi. Documentation.

After a short historical review a proposal is made for the definition of nasal polyposis. The authors studied 350 CT-scans of patients with nasal complaints. In a high percentage anatomical anomalies were observed. In 57.5% of the CT-scans sinus mucosal disease was visible. In all patients with maxillary sinus disease polyps (rounded structures) could be found; in 31% these polyps were mainly of grade 2. From a retrospective study of 111 biopsies of nasal polyposis (65 patients) it became clear that different polyps from the same patient showed substantial difference in cellular content, i.e. presence of eosinophils, neutrophils, plasma cells, glands, ducti and thickening of the basal membrane. As oral acetylsalicylic acid provocation may be hazardous in ASA-sensitive patients, the authors developed a nasal aspirin provocation test. This nasal ASA test was carried out in 10 normal test subjects, 10 patients with aspecific hyperreactivity, 10 atopic patients and 16 patients with polyposis nasi. The reproducibility of the test, however, was so poor that the nasal ASA challenge test in its present form does not appear to be of any great clinical value. Finally, the authors discuss the physiopathology of nasal polyposis.

Adult↗
PubMed1989

[New possibilities and aspects of low-field magnetic resonance tomography].

Worldwide, MRI is going up to higher field-strength. For imaging, magnets with field-strength between 0.2 and about 2.5 Tesla are installed. Below 0.2 Tesla, Low-Field-systems have been used in research-projects to optimize image quality. New developments of 0.064 Tesla Permanent-Magnet-MRI are hopeful for clinical work. Future possibilities of Low-Field-MRI are shown. The advantages of this system are good image quality by low initial start-up and operating costs as well as ease of sitting and lack of need for cryogens. The open design has excellent patient acceptance and allows to examine patients with claustrophobia feelings. It allows easier monitoring during the examination-especially children and patients with cancer or polytraumatic diseases. The introduction of more affordable MRI-systems of low-field-strength may decrease the cost of MRI to the point where it is competitive with computer tomography.

Costs and Cost Analysis↗
PubMed1989

[CAT-scan study of the prevalence of sinus disorders and anatomical variations in 196 children].

CT-scan was used to examine rhinosinusitis in the developing sinuses; 196 children aged from 3 to 14 years were selected on the base of their chronic rhinorrhea, nasal congestion and cough. The patient group was subdivided into six age groups (3-4, 5-6, 7-8, 9-10, 11-12 and 13-14 years). In the youngest age group, the authors noted maxillary involvement in 63%, ethmoidal involvement in 58%, and even sphenoidal sinus involvement in 29% of the children. Involvement decreased gradually with age, with 10% of ethmoidal and 0% of sphenoidal involvement in the 13-14 years age group. Maxillary sinusitis, however, persisted very frequently in the oldest age group (65%). Frontal involvement seems to become significant at the age of 7-8 years (7%) but it never exceeds 15% (11-12 age group). Septal deviations occurred in 16% of the youngest up to 72% in the oldest age group. A prevalence of bullous conchae increased with age too, although less prominently.

Adolescent↗
PubMed1989

The Budd-Chiari syndrome caused by a zygomycete. A new pathogenesis of hepatic vein thrombosis.

The clinical history of a 60-year-old woman suffering from chronic lymphocytic leukemia with sudden deterioration and death is reported. The postmortem macroscopic and microscopic findings included pulmonary aspergillosis and pulmonary zygomycosis (mucormycosis). Hematogenous dissemination of the zygomycete causing cardiac zygomycosis, cerebral infarcts due to vascular occlusion by hyphae, and thrombosis of the major hepatic veins (Budd-Chiari syndrome) with submassive necrosis of the right liver lobe were also observed. To our knowledge, this is the second report dealing with occlusion of the hepatic veins caused by a fungus and the first study reporting the Budd-Chiari syndrome due to a mold of the subclass Zygomycetes.

Budd-Chiari Syndrome↗
PubMed1988

Localization of human breast tumors grafted in nude mice with a monoclonal antibody directed against a defined cell surface antigen of human mammary epithelial cells.

A mouse monoclonal antibody (BLMRL-HMFG-Mc5) prepared against a defined cell surface antigen of human mammary epithelial cells, non-penetrating glycoprotein (NPGP), was used in imaging and distribution studies in athymic nude mice grafted with human breast tumors. For in vivo tissue distribution studies, 125I-labeled monoclonal antibody was injected into nude mice carrying simulated metastases of human tumors (breast and colon carcinomas). After 22-24 hr the amount of radioactivity per gram of tissue was 3-4 times higher in the breast tumor than in liver, brain, lung, muscle, or spleen. In contrast, colon carcinoma tissue, grafted and treated likewise, did not show higher accumulation of radioactivity relative to other tissues. At 4 days, the incorporation in breast tumors remained almost as high, while the circulating radioactive tracer and the incorporation in tissues other than breast had fallen significantly. In tumor imaging studies, breast tumor masses as small as 4 mm in diameter were clearly localized on a whole body scan using 131I-labeled BLMRL-HMFG-Mc5 antibodies with a High-Purity germanium gamma camera. Normalization of 131I-distribution to that of 99mTc-pertechnetate increased the specificity of this imaging methodology. The quantitative density of 131I-label was 2-3 fold higher over the breast tumor than over comparable areas of the mouse. No positive localization images were obtained for similar implants of colon and lung carcinomas or melanomas after injections of 131I-labeled BLMRL-HMFG-Mc5. Localization of human breast tumors in this model can be achieved with 131I-labeled anti-breast epithelial monoclonal antibodies.

Animals↗
PubMed1988

Magnetic localization of neuronal activity in the human brain.

The performance of a cryogenic system that monitors the extracranial magnetic field simultaneously at 14 positions over the scalp has been evaluated to determine the accuracy with which neuronal activity can be located within the human brain. Initially, measurements were implemented on two model systems, a lucite sphere filled with saline and a model skull. With a magnetic field strength similar to that of a human brain, the measurement and analysis procedures demonstrated a position accuracy better than 3 mm, for a current dipole 3 cm beneath the surface. Subsequently, measurements of the magnetic field pattern appearing 100 ms after the onset of an auditory tone-burst stimulus were obtained in three human subjects. The location of the current dipole representing intracellular ionic current in active neurons of the brain was determined, with 3-mm accuracy, to be within the cortex forming the floor of the Sylvian fissure of the individual subjects, corresponding closely to the Heschl gyrus as determined from magnetic resonance images. With the sensors placed at appropriate positions, the locations of neuronal sources for different tone frequencies could be obtained without moving the recording instrument. Adaptation of activity in human auditory cortex was shown to reveal long-term features with a paradigm that compared response amplitudes for three tones randomly presented.

Brain↗
PubMed1988

Epidemiologic and immunologic evaluation of an outbreak of canine blastomycosis.

Five confirmed cases of canine blastomycosis occurred over the 10-month period of December 1983 to September 1984 in a south-eastern Wisconsin colony of 30 dogs maintained for sled competition. Contrary to other published reports of canine blastomycosis, the sex-specific attack rates were higher among females than males. Four of the five confirmed cases and all four deaths occurred among young female dogs. Differences in the age distribution and/or the micro-environment of the females may have contributed at least in part to the difference in sex-specific attack rates. The serologic response and leukocyte function of the clinically affected and apparently healthy dogs from this colony were assessed during the outbreak. A survey of the adult dogs in the colony suggested that the mitogen-induced lymphocyte blastogenesis of dogs with clinical signs of blastomycosis was suppressed compared with that of dogs that remained free of clinical signs. In contrast to previous reports that autologous sera from dogs and humans with clinical blastomycosis inhibited mitogen-induced lymphocyte blastogenesis, lymphocyte responsiveness was similar to, or greater in the presence of autologous canine serum than it was in the presence of fetal bovine serum.

Animals↗