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Biomedical subjects

U Tylen

Publications and source records attributed to U Tylen.

5 recordsLinked to original sources
PubMed2003

Evaluation of various attenuation corrections in lung SPECT in healthy subjects.

The effect of increasingly more sophisticated attenuation correction methods on image homogeneity has been studied in seven healthy subjects. The subjects underwent computed tomography (CT), single photon emission computed tomography (SPECT) and transmission computed tomography (TCT) of the thorax region in the supine position. Density maps were obtained from the CT and TCT studies. Attenuation corrections were performed using five different methods: (1) uniform correction using only the body contour; (2) TCT based corrections using the average lung density; (3) TCT based corrections using the pixel density; (4) CT based corrections using average lung density; and (5) CT based corrections using the pixel density. The isolated attenuation effects were assessed on quotient images generated by the division of images obtained using various attenuation correction methods divided by the non-uniform attenuation correction based on CT pixel density (reference method). The homogeneity was calculated as the coefficient of variation of the quotient images (CV(att)), showing the isolated attenuation effects. Values of CV(att) were on average 12.8% without attenuation correction, 10.7% with the uniform correction, 8.1% using TCT map using the average lung density value and 4.8% using CT and average lung density corrections. There are considerable inhomogeneities in lung SPECT slices due to the attenuation effect. After attenuation correction the remaining inhomogeneity is considerable and cannot be explained by statistical noise and camera non-uniformity alone.

Adult↗
PubMed1997

Stimulable phosphor plates in chest radiology

LANGUAGE="EN">Summary. The stimulable phosphor plate technique has revolutionised radiology with portable equipment. The image quality permits diagnosis under difficult control conditions (ICUs). In order to achieve a signal-to-noise ratio, and therefore a contrast resolution similar to the commonly used film/screen systems, a higher radiation dose is needed. However, overall, with this technique a radiation dose reduction may be achieved as a result of the elimination of the need for retakes. The available stimulable phosphor plate systems, with adequate image processing are reliable, and at least as good as conventional film/screen systems for diagnosis in chest radiography. There are, however, other aspects that make the stimulable phosphor plate technique particularly appealing. Firstly, its reproducibility, which particularly in chest radiography allows images to be obtained with the same grey scale and darkness. Secondly, as this technique permits digital archiving and visualisation of images on screen, images can be rapidly distributed over a network making them available when and where they are needed.

Journal Article↗
PubMed1991

Obliterative bronchiolitis following lung transplantation. Diagnostic utility of aerosol ventilation lung scanning and high resolution CT.

A serious and often fatal complication of heart-lung transplantation is the development of obliterative bronchiolitis (OB). Currently the screening for OB is based on symptoms, pulmonary function tests, and transbronchial biopsies. The chest radiographs are often normal with OB. Obliterative bronchiolitis produces luminal narrowing of both bronchioles and bronchi resulting in areas of peripheral consolidation and occasional bronchiectasis. We report a patient in whom a chest film was normal, an aerosol ventilation lung scan was abnormal while a perfusion study was mildly abnormal. Simultaneously, routine CT was essentially normal while high resolution CT with 1 mm thick sections was clearly abnormal and demonstrated areas of consolidation. These imaging modalities detected clear-cut abnormalities at a time when the patient was symptomatic but prior to the development of demonstrable abnormality on chest radiograph.

Adult↗
PubMed1988

Lung function in workers exposed to soft paper dust.

In a cross-sectional study, 13 nonsmoking men with heavy exposure to paper dust were compared with 14 unexposed men, mainly office workers, employed at the same paper mill. They were studied using questionnaires, physical examinations, pulmonary function studies, and chest radiographs. Among those exposed there was an increased lung elastic recoil pressure (Pel) compared with controls which was significant (p less than 0.05) at the maximal level of total lung capacity (100% TLC). Furthermore, among the exposed workers there was also a significantly (p less than 0.05) decreased residual volume (RV). Two of the exposed men underwent lung biopsies, one of which showed fibrotic alveolar walls. Among the exposed there was also a significant (p less than 0.05) predominance of symptoms from the lower respiratory tract. We suggest that the observed pulmonary function impairment taken together with the histological examination of the lung biopsies are signs of a nonspecific reaction to high levels of paper dust.

Adult↗