急性心筋梗塞後の心臓リハビリテーション継続への退院支援および連携に関する実態調査 [in Japanese] Survey on discharge planning and cooperation on cardiac rehabilitation after acute myocardial infarction [in Japanese]
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Objectives : In this study, we evaluated a computerized scheme for automated setting of grayscale display for diffusion-weighted magnetic resonance images (DWI) of brains based on the density histogram analysis against existing standard methods for setting display conditions for DWI to ascertain whether the automated methods provided more consistent display. Methods : We used 60 brain DWI cases, which were scanned within the first 6 hours after stroke onset. In our computerized scheme, the existing method of setting the display conditions for DWI using the thalamic signal intensity in a b0 image was first applied for one DWI case. The display grayscale was converted into 8-bits by the linear grayscale transfer technique. The density histogram was then determined, and the full width of pixel values corresponding to half of the maximum (FWHM) in density histogram was determined. The DWI volumes were then created for 60 cases, and the density histogram was determined from the brain region based on DWI volumes. The pixel value corresponding to the maximum in density histogram was determined for DWI volume. The display grayscale for DWI volumes was adjusted by setting the determined pixel value as a window center, and the pixel value that FWHM in the density histogram of adjusted DWI is corresponding to FWHM previously obtained as a window width. To compare the existing manual method to the automated method, the variation in signal intensity and image contrast was evaluated subjectively using a two-alternative-forced-choice test for pairs of images prepared by each method. Results : The subjective similarity for pairs of DWI volumes adjusted using our computerized scheme was judged to be more similar than those using existing manual methods by 71.7%, which indicated clearly our automated method provided more consistent display. Conclusions : Our computerized scheme is a promising technique for accurate, prompt automated setting of display conditions in brain DWI, and may be useful to radiologists in decision-making for radiological diagnosis.
- Bulletin of Gunma Prefectural College of Health Sciences
Bulletin of Gunma Prefectural College of Health Sciences 4, 67-76, 2009-03
Gunma Prefectural College of Health Sciences