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Biomedical subjects

H Manninen

Publications and source records attributed to H Manninen.

62 records · Page 4Linked to original sources
PubMed1984

An evaluation of different imaging chains in clinical chest radiography.

Six imaging techniques in clinical chest radiography have been evaluated: four film-screen combinations in the conventional grid technique and two combinations in the air gap technique. Five parameters characterising the quality of a chest radiograph were evaluated by three radiologists and one chest physician by using a nominal grading scale from -2 to +2 compared with the standard technique. The quality parameters judged were: the visibility of peripheral lung vessels, lung parenchyme, the pulmonary hilum, and lung structure behind the heart shadow, as well as the visibility of miscellaneous findings of clinical interest. The air gap technique was shown to be superior to the ordinary grid technique. The diagnostic quality of chest radiography does not necessarily deteriorate with the screen speed. However, statistically significant differences were noticed, even between techniques which had equal speed and physical resolution.

Aged↗
PubMed1982

Physical characteristics of four roentgenographic chains proposed for chest radiography.

Four types of roentgenographic chains have been studied in the present work: the ordinary grid technique with 1 screen-film combinations, the air gap technique with 8 screen-film combinations, the roentgen photofluorography (RP technique) and the spotfilm technique. To study resolution and contrast properties a gold plate was radiographed in a 20 cm thick water phantom and the equivalent passband and the inherent subject contrast were calculated. The effect of motion unsharpness on resolution was examined theoretically. The RMS nose and the speed of each technique were evaluated. The air gap technique proved to be a good alternative to the ordinary grid technique. Rare earth screens decrease the radiation dose to at least one third of that of a medium-speed film/calcium tungstate screen combination without noticeably impairing resolution, contrast or noise properties, but reducing motion unsharpness considerably. Differences between various screen-film combinations of equal speed were not very marked. The RP technique proved to be poorest in almost all respects. The spotfilm technique seems worth developing for chest radiography.

Humans↗
PubMedDate not supplied

Percutaneous endovascular stenting: development, investigation and application.

Percutaneous endovascular stenting (PES), a new and alternative approach of interventional radiologic techniques, has encouraging potentials for management of vascular obstructive diseases. The most important role of PES is to prevent the risk of abrupt closure and to reduce the rate of early and late post-angioplasty restenosis (PARS) of PTA. Because of different working mechanisms, various stents show different advantages and disadvantages. Specific indications of PES are: (1) further compensation for failed PTA, (2) management of complications due to PTA and (3) primary treatment of vascular obstructive diseases. Based on a preliminary comparison with atherectomy, laser angioplasty and PTA, PES seems to provide an advantage for long-term patency of large caliber vessels such as iliac arteries, while more significant problems still exist in PES with small caliber vessels such as femoral-popliteal and coronary arteries. Further comparative clinical research is required to establish the utility of PES among other intraluminal techniques of vascular interventions.

Animals↗
PubMedDate not supplied

Image processing in digital chest radiography: effect on diagnostic efficacy.

The usefulness of digital image processing of chest radiographs was evaluated in a clinical study. In 54 patients, chest radiographs in the posteroanterior projection were obtained by both 14 inch digital image intensifier equipment and the conventional screen-film technique. The digital radiographs (512 x 512 image format) viewed on a 625 line monitor were processed in three different ways: (1) standard display; (2) digital edge enhancement for the standard display; and (3) inverse intensity display. The radiographs were interpreted independently by three radiologists. The diagnoses were confirmed by CT, follow-up radiographs and clinical records. Chest abnormalities of the films analyzed included 21 primary lung tumors, 44 pulmonary nodules, 16 cases with mediastinal disease and 17 cases with pneumonia/atelectasis. Interstitial lung disease, pleural plaques, and pulmonary emphysema were found in 30, 18 and 19 cases, respectively. The sensitivity of conventional radiography when averaged overall findings was better than that of the digital techniques (P less than 0.001). The differences in diagnostic accuracy measured by sensitivity and specificity between the three digital display modes were small. Standard image display showed better sensitivity for pulmonary nodules (0.74 vs 0.66; P less than 0.05) but poorer specificity for pulmonary emphysema (0.85 vs. 0.93; P less than 0.05) compared with inverse intensity display. We conclude that when using 512 x 512 image format, the routine use of digital edge enhancement and tone reversal at digital chest radiographs is not warranted.

Adolescent↗
PubMedDate not supplied

A three-contrast, metal test pattern (Snellen E-plate) in evaluation of imaging techniques in clinical chest radiography.

A metal test pattern based on a minified Snellen-type E-plate was evaluated in testing six imaging techniques for chest radiography. The device consisted of three contrast zones and it was attached to the patient's back over the right lung during chest radiography. The values for visual detectability of the E-figures were compared with the film scores obtained by grading the radiographs with respect to visibility of diagnostically important anatomic details. The test plate proved to be a simple, quick and reproducible tool for testing several imaging techniques at the same time. The E-plate results were similar to those of the visual grading analysis in most respects. A few discrepancies existed, which were probably due to the inability of the test pattern to fully consider the effect of motion unsharpness and varying scattering conditions within the human thorax, as well as to great differences in roentgen ray absorption properties between Au and tissues.

Humans↗
PubMedDate not supplied

Large-screen image intensifier photofluorography compared with full-size screen-film technique in chest radiography.

Large-screen image intensifier photofluorography revealed a radiation dose and exposure time of about one third of those of a medium speed rare-earth screen/film (Trimax T4/XD) combination for full-size chest radiography. The resolving power of the former technique is somewhat poorer and there is a moderate electron-òptical distortion in the peripheral field. In clinical chest radiography photospot films showed excellent demonstration of the central areas of the image but slight deterioration in peripheral parts. The minification effect of the photofluorographic films is advantageous for visual perception of many anatomic details on chest radiographs. The type of viewing device for photospot films is important.

Aged↗
PubMedDate not supplied

Large-image intensifier photofluorography and conventional radiography in pulmonary emphysema. Correlation with computed tomography.

Large-screen image intensifier (II) photofluorography was compared with full-size screen-film chest radiography in the diagnosis of pulmonary emphysema in 84 patients. Photospot films and conventional radiographs were interpreted independently by three radiologists. Computed tomography (CT) was used as an independent reference technique, and diagnostic performance of chest radiography in various CT patterns of emphysema was evaluated. The difference in diagnostic sensitivity for emphysema in favor of conventional chest radiography over photofluorography (0.65 versus 0.56) was statistically significant (p less than 0.05). Specificity of the imaging modalities was equal: 0.78 in full-size films and 0.77 in photospot films. All CT patterns of emphysema had great false negative response rates in chest radiography, which is an inaccurate technique for the diagnosis of emphysema. CT is required for reliable radiologic evaluation of emphysema.

Emphysema↗