PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “EMI”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources

Anesthesia for EMI scanning in infants and small children.

Computerized transverse axial scanning is a new, noninvasive method of diagnosing intracranial and orbital lesions. It is mandatory that the patient's head be motionless throughout the scanning procedure. This requirement creates problems in managing infants and small children for the scanning process. Ketamine hydrochloride was given intramuscularly to produce the desired motionless stated in 47 consecutive infants and small children. Satisfactory scans were obtained in all except two cases. Contraindications and precautions to be observed using this technic are discussed. It is believed that intramuscularly administered ketamine is a safe, effective means of providing immobilization for EMI scanning in infants and small children who are normotensive and show no evidence of definitely increased intracranial pressure.

Anesthesia, General↗

H-Y antigen expression in temperature sex-reversed turtles (Emys orbicularis).

H-Y antigen has been used as a marker for the heterogametic sex and is assumed to be an organizing factor for the heterogametic gonad. In the turtle Emys orbicularis, H-Y antigen is restricted to the female cells, indicating a female heterogamety (ZZ/ZW) sex-determining mechanism. Moreover, the sexual differentiation of the gonads is temperature sensitive, and complete sex reversal can be obtained at will. In this framework the relationships between H-Y antigen, temperature, and gonadal phenotype were studied. Mouse H-Y antiserum was absorbed with blood and gonadal cells of control wild male and female adults, and with blood and gonadal cells from three lots of young turtles from eggs incubated at 25-26 degrees C (100% phenotypic males), at 30-30.5 degrees C (100% phenotypic females), or at 28.5-29 degrees C (majority of females with some males and intersexes). The residual activity of H-Y antiserum was then estimated using an immunobacterial rosette technique. In adults, both blood cells and gonadal cells were typed as H-Y negative in males and as H-Y positive in females. In each of the three lots of young, blood cells were H-Y negative in some individuals and H-Y positive in others. The proposed interpretation is that the H-Y negative individuals were genotypic males (ZZ) and the H-Y positive were genotypic females (ZW). The gonads of these animals were then pooled in different sets according to their sexual phenotype and to the presumed genotypic sex (i.e., blood H-Y phenotype). Testicular cells were typed as H-Y negative in genotypic males as well as in the presumed sex-reversed genotypic females; likewise, ovarian cells were typed as H-Y positive in genotypic females as well as in the presumed sex-reversed genotypic males. These results provide additional evidence that H-Y antigen expression is closely associated with ovarian structure in vertebrates displaying a ZZ/ZW sex-determining mechanism.

Animals↗

Resetting of DDD pacemakers due to EMI.

Multiprogrammable pacemakers have long been subject to inappropriate reprogramming and electromagnetic interference (EMI). A limited clinical experience with DDD pacing systems precludes the significance of such phenomena in these units. Since August 1981, in a series of 140 DDD systems, certain units demonstrated consistent and reproducible resetting to the back-up modes caused by electrocautery. One unit was permanently reset to the VOO mode. These observations suggest the need for renewed caution at the time of surgery; they also underscore the importance of a thorough understanding of any DDD system and careful follow-up so that such phenomena will not be misinterpreted as pacemaker failure, resulting in erroneous pacemaker removal.

Arrhythmias, Cardiac↗

Effects of blood processing techniques on sodium and potassium values: a comparison between Aldabra tortoises (Geochelone gigantea) and Burmese mountain tortoises (Manouria emys).

BACKGROUND: Hematologic and plasma biochemical evaluations are routinely used in evaluating the chelonian patient, but appropriate processing techniques have been minimally defined. OBJECTIVES: This study was designed to compare the effects of temperature, time, anticoagulant, and species on sodium and potassium values in the Aldabra tortoise (Geochelone gigantea) and the Burmese mountain tortoise (Manouria emys). METHODS: Blood samples from 7 Aldabra tortoises and 8 Burmese mountain tortoises were collected into tubes without anticoagulant and tubes containing lithium heparin. Sodium and potassium concentrations were measured by flame photometry in serum and plasma harvested immediately after collection and from aliquots of whole blood stored at 4 degrees C and 25 degrees C for 5 to 120 minutes. RESULTS: In Aldabra tortoises, storage time and temperature had no significant effect on potassium concentrations in heparinized blood and in blood without anticoagulant. However, sodium concentrations in serum and plasma decreased significantly in samples without anticoagulant stored at 4 degrees C and 25 degrees C and in heparinized samples stored at 4 degrees C. In Burmese mountain tortoises, potassium concentrations in serum and plasma increased significantly with time in samples without anticoagulant and in heparinized samples stored at 4 degrees C and 25 degrees C, but the increases were less at 4 degrees C. Sodium concentrations in serum and plasma decreased significantly in blood without anticoagulant and heparinized blood stored at 4 degrees C and 25 degrees C. CONCLUSIONS: Storage of blood samples with and without anticoagulant at 4 degrees C significantly improved the stability of potassium and sodium concentrations in both species of tortoises. Early separation of red cells from serum or plasma after blood collection is especially important to ensure the reliability of potassium measurements.

Animals↗

An evaluation of the performance characteristics of different types of collimators used with the EMI brain scanner (MKI) and their significance in specific clinical applications.

The characteristics of various types of collimators have been studied systematically for the EMI Mark I brain scanner. The degree of collimation ranged from the 13-mm adjacent A and B slices to 3-mm separated slices. Multiple phantom studies (including variable density immiscible liquid interfaces) have been performed to evaluate the effect of collimation on (a) the line-spread function, (b) the change in effective absorption number, and (c) volume averaging. Effects associated with the technique settings involving the kVp, the mA, and the scan time were also investigated. The results of TLD dose measurements as a function of collimation are presented. The significance of collimation in specific clinical studies involving small, fairly well-circumscribed lesions is discussed.

Brain Diseases↗

A clinical study of the EMI scanner: implications for provision of neuroradiological services.

The records of the first 571 patients to be examined with an EMI brain scanner were assessed. The patients were divided into diagnostic categories according to their clinical presentation. The intracranial investigations that would have been performed had the scanner not been available were compared with the investigations that were actually performed. As expected, the number of contrast investigations fell, but the reduction surpassed expectation. If the full clinical impact of the scanner is to be realised the patient's illness must be defined in detail and strict attention paid to radiographic detail. By reducing the number of special contrast investigations use of the scanner enables existing contrast facilities to serve a wider population; and use of the brain scanner in district general hospitals would improve the service to patients, especially those with head injuries.

Angiography↗

Computed tomography with the EMI scanner in the diagnosis of primary and metastatic intracranial neoplasms.

The findings and diagnostic results in 600 examinations of primary and metastatic intracranial neoplasms performed at one hospital with the EMI scanner are presented and the effectiveness of this method is compared with that of radionuclide imaging, cerebral angiography, and pneumoencephalography. The computed scan proved to be highly reliable in the diagnosis of glioma, cerebral metastases, meningioma, and acoustic neuroma.

Adenocarcinoma↗

A thin-section collimator for the EMI scanner.

The thinnest pair of slices provided by the EMI scanner is 8 mm, producing an overlap of 6 mm. Resolution is reduced by averaging the density of structures throughout the thickness of the slice. The authors described special collimators which provide thinner slices with no overlap and thereby improve the quality of orbital scans.

Humans↗

Performance evaluation and quality assurance of computed tomography scanners, with illustrations from the EMI, ACTA, and Delta scanners.

Performance evaluation of equipment for computed tomography (CT) involves the integration of: (a) establishing performance criteria; (b) designing and implementing test procedures; and (c) reconciling test results in terms of desired performance. Precision (noise), contrast scale, linearity, accuracy, spatial independence, spatial resolution, artifacts, reproducible performance, and patient exposure are several parameters discussed, as are problems of measurement with regard to non-water bath scanners. Performance and quality control tests for the ACTA, Delta, and EMI scanners are outlined. Guidance for the prospective purchaser of CT equipment is presented as a summary of the ideas discussed.

Computers↗

Comparative modulation transfer functions of the EMI and Delta scanners.

Spatial resolution of the EMI and Delta computed tomographic scanners has been measured by recording the response to a nylon and water sunburst phantom (Siemens star) and calculating the modulation transfer function at radii corresponding to various spatial frequencies. The resolution appears to be related primarily to the size of the matrix element, and exhibits an upper cut-off frequency somewhat in excess of 3 cycles/cm.

Computers↗

Cerebrospinal fluid spectrophotometry and computerized transverse axial tomography (EMI scanning) in cerebrovascular diseases. Comparative study between two actual diagnostic methods in cerebrovascular disorders.

51 patients with cerebrovascular diseases were examined by CSF spectrophotometry (CSF-SPE) and computerized transverse axial tomography (CTAT: EMI scanning), most cases being followed by several examinations. Specific diagnoses were detected in 98 (CSF-SPE) and 75% (CTAT) of the cases, generally by only one examination. In cases examined angiographically or by isotope encephalography, the corresponding figures were 50 and 0%. The combination of CSF-SPE and CTAT examination obviously means a breakthrough in diagnosis of cerebrovascular diseases which is naturally a prerequisite for the more rational therapy of these common and frequently disabling disorders.

Angiography↗

A comparative study of EMI shielding properties of carbon nanofiber and multi-walled carbon nanotube filled polymer composites.

Electromagnetic interference shielding properties of carbon nanofiber- and multi-walled carbon nanotube-filled polystyrene composites were investigated in the frequency range of 8.2-12.4 GHz (X-band). It was observed that the shielding effectiveness of composites was frequency independent, and increased with the increase of carbon nanofiber or nanotube loading. At the same filler loading, multi-walled carbon nanotube-filled polystyrene composites exhibited higher shielding effectiveness compared to those filled with carbon nanofibers. In particular, carbon nanotubes were more effective than nanofibers in providing high EMI shielding at low filler loadings. The experimental data showed that the shielding effectiveness of the composite containing 7 wt% carbon nanotubes could reach more than 26 dB, implying that such a composite can be used as a potential electromagnetic interference shielding material. The dominant shielding mechanism of carbon nanotube-filled polystyrene composites was also discussed.

Dose-Response Relationship, Radiation↗

Computer subtraction in regional cerebral blood-volume measurements using the EMI-Scanner.

A computerized subtraction technique has been described to measure regional cerebral blood volume (rCBV) using the EMI-Scanner in a group of 13 patients. Sodium iothalamte was injected intravenously (1-75 ml./kg) to increase the absorption of X rays in the cerebral circulation. Significant regional differences in CBV were shown, values in the frontal and temporal regions being lower than the mean hemisphere value (4-9 +/- 0-7) and higher in the occipital region. The left hemisphere showed a significantly higher CBV when compared with the right. Measurements of CBV in the cortex showed no regional variation, but the mean cortical value of 6-0 +/- 1-8 was significantly higher than the hemisphere mean.

Blood Volume↗

Computerized tomography using the EMI general purpose scanner.

The EMI general Purpose Scanner is briefly described, with particular reference to the use of window height and window width variations. Patient preparation in relation to movement artefacts and contrast medium is considered, and a method of localization of tomographic sections is described. The Scanner produces brain examinations of high quality. Because a head water bath is no longer required, the base of the skull can also be examined. In the thorax computerized tomography is particularly valuable in showing pleural disease in the forms of thickening, plaques or tumours, and in demonstrating retrosternal lymph node enlargement. Small peripheral metastases can be identified when not shown by conventional tomography. In the abdomen lymph node masses, retroperitoneal tumours and pancreatic disease has been identified, often more completely than by other methods, or where other methods have failed. This has proved particularly valuable in the grading of malignant disease and in the monitoring of subsequent treatment. It is particularly helpful in the planning of radiotherapy. Metastases in liver and bone can be clearly defined when still quite small (0-5.1 cm), but comparison with other methods of diagnosis such as grey scale ultrasound and isotope scanning will be needed before the role of computerized tomography in evaluating these lesions is known.

Evaluation Studies as Topic↗

Measurement of regional cerebral blood volume using the EMI 1010 scanner.

Regional cerebral blood volume (rCBV) was measured in 14 patients with normal CT scans. An EMI CT 1010 scanner was used in combination with a computer subtraction technique. The mean CBV in the cortex was 5.0 ml/100 ml of tissue and 2.2 in the white matter. Regional differences were not significant and no difference was found between the right and left hemispheres.

Adolescent↗

Determination of cerebral blood flow with the EMI CT scanner.

Cerebral blood flow (CBF) detemination were made in seven baboons and two patients with the EMI CT dedicated head scanner. The method for determining the CBF was tested and measurements were made during physiological states elicited by changes in pCO2 and depth of anaesthesia. The method has a number of advantages, particularly for assessing CBF responses to pCO2 changes.

Animals↗