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Cineangiography and arterial flow disturbances
- 1992
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Proceedings (redaktörskap) (refereegranskat)abstract
- Disturbances in arterial flow are believed to influence the localization and development of atherosclerotic plaques. The femoral arteries of 26 patients were studied with cineangiography, after which the films were digitized and analyzed with an image analysis computer. The image sequence was converted to a set of time-intensity curves, from which time parameters were calculated, representing the arrival time of the contrast medium at each pixel. In the resulting parametric images, zones of delayed contrast filling (ZDF) were identified by an adaptive thresholding, which identifies lighter regions within the vessel, excluding the smallest ones. The ZDF, which have been shown, in a model study, to correspond to disturbed flow, were more frequent in the inner curvature than in the outer curvature of the curved vessels. Accordingly, they were more frequent along the lateral wall than along the medial wall of the artery. Several ZDF were also found in the vicinity of bifurcations. Most of the findings tally closely with fluid mechanical theory. In future studies, flow disturbances are to be correlated with the progression of atherosclerotic lesions.
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| 4. |
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| 5. |
- Henriksson, Lars, et al.
(författare)
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Assessment of congestive heart failure in chest radiographs : Observer performance with two common film-screen systems
- 1990
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 31:5, s. 469-471
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Tidskriftsartikel (refereegranskat)abstract
- The effect of observer variations and film-screen quality on the diagnosis of congestive heart failure based on chest radiographs was studied in 27 patients. For each patient, two films were exposed, one with the Kodak Lanex Medium system and one with the Agfa MR 400 system. The films were presented to three observers who assessed the presence of congestive heart failure on a three-graded scale. The results showed no significant difference between the two systems but large systematic differences between the observers. There were also differences between the two ratings by the same observer that could not be explained by the film-screen factor. It is concluded that the choice between these two systems is of little importance in view of the interobserver and intraobserver variability that can exist within the same department.
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| 6. |
- Henriksson, L, et al.
(författare)
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Assessment of congestive heart failure in chest radiographs. Observer performance with two common film-screen systems.
- 1990
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Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 31:5, s. 469-471
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Tidskriftsartikel (refereegranskat)abstract
- The effect of observer variations and film-screen quality on the diagnosis of congestive heart failure based on chest radiographs was studied in 27 patients. For each patient, two films were exposed, one with the Kodak Lanex Medium system and one with the Agfa MR 400 system. The films were presented to three observers who assessed the presence of congestive heart failure on a three-graded scale. The results showed no significant difference between the two systems but large systematic differences between the observers. There were also differences between the two ratings by the same observer that could not be explained by the film-screen factor. It is concluded that the choice between these two systems is of little importance in view of the interobserver and intraobserver variability that can exist within the same department.
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| 8. |
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| 9. |
- Smedby, Örjan
(författare)
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A scanning system for digital analysis of cineangiography films
- 1992
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Ingår i: Computer Methods and Programs in Biomedicine. - 0169-2607 .- 1872-7565. ; 39:1-2, s. 103-111
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Tidskriftsartikel (refereegranskat)abstract
- A system for scanning and digital analysis of cinefilms is presented and its performance is compared with entirely digital radiographic equipment. Apart from the difference between logarithmic and linear gray-scale representation, a higher noise level was found in the scanning system. When its spatial resolution was assessed visually, it was comparable to that of the digital system, although lower than when the cinefilming and scanning steps were evaluated separately. Algorithms for the correction of varying exposure and geometric ("pin-cushion") distortion are also presented. It is concluded that digital analysis after scanning of cinefilms can be a useful alternative to completely digital cineradiographic studies.
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| 10. |
- Smedby, Örjan, et al.
(författare)
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Flow disturbances in early femoral atherosclerosis : An in vivo study with digitized cineangiography
- 1993
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Ingår i: Journal of Biomechanics. - 0021-9290 .- 1873-2380. ; 26:9, s. 1105-1115
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Tidskriftsartikel (refereegranskat)abstract
- Disturbances in arterial flow are believed to influence the localization and development of atherosclerotic plaques. The femoral arteries of 26 patients were studied with cineangiography, after which the films were digitized and analyzed with an image analysis computer. The image sequence was converted to a set of time-intensity curves, from which time parameters were calculated, representing the arrival time of the contrast medium at each pixel. In the resulting parametric images, zones of delayed contrast filling (ZDF) were identified by an adaptive thresholding, which identifies lighter regions within the vessel, excluding the smallest ones. The ZDF, which have been shown, in a model study, to correspond to disturbed flow, were more frequent in the inner curvature than in the outer curvature of the curved vessels. Accordingly, they were more frequent along the lateral wall than along the medial wall of the artery. Several ZDF were also found in the vicinity of bifurcations. Most of the findings tally closely with fluid mechanical theory. In future studies, flow disturbances are to be correlated with the progression of atherosclerotic lesions.
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