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- Birnbaum, Bernard A., et al.
(författare)
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Hepatic hemangiomas: diagnosis with fusion of MR, CT, and Tc-99m-labeled red blood cell SPECT images
- 1991
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Ingår i: Radiology. - : Radiological Society of North America. - 0033-8419 .- 1527-1315. ; 181:2, s. 469-474
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Tidskriftsartikel (refereegranskat)abstract
- A method of image analysis was developed for correlation of hemangiomas detected at computed tomography {(CT)} and/or magnetic resonance {(MR)} imaging with increased blood pool activity evident at single photon emission {CT} {(SPECT)} performed after labeling of red blood cells with technetium-99m. Image analysis was performed in 20 patients with 35 known hepatic hemangiomas. After section thickness and pixel sizes of the different studies were matched, intrinsic landmarks were chosen to identify anatomically corresponding locations. Regions of interest {(ROIs)} drawn on the {CT} and/or {MR} images were translated, rotated, and reprojected to match the areas of interest on the corresponding {SPECT} images by means of a two-dimensional polynomial-based warping algorithm. Analysis of {ROIs} on 30 {SPECT-MR} and 20 {SPECT-CT} pairs of registered images provided absolute confirmation that 34 suspected hemangiomas identified on {SPECT} images correlated exactly with lesions seen on {CT} and/or {MR} images. Accuracy of fusion was within an average of 1.5 pixels +/- 0.8 (+/- 1 standard deviation). The technique enabled diagnostic confirmation of hemangiomas as small as 1.0 cm and proved useful for evaluating lesions located adjacent to intrahepatic vessels.
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| 2. |
- Weinstein, M.C., et al.
(författare)
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A Note on QALYs, Time Tradeoff, and Discounting
- 1994
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Ingår i: Medical Decision Making. - 1552-681X .- 0272-989X. ; 14:2, s. 188-193
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Tidskriftsartikel (refereegranskat)abstract
- The theoretical model of QALYs is based on risk neutrality with respect to life years or constant proportional risk posture with respect to life years. It is shown that discounting of QALYs is inconsistent with these assumptions. For discounting to be consistent with individual preferences in a QALY model, individuals have to be risk-neutral with respect to discounted life years or exhibit constant proportional risk posture with respect to discounted life years. For the time-tradeoff method to be consistent with these assumptions, the QALY weights have to be derived by dividing the number of discounted life years in full health by the number of discounted life years in the assessed health states. Key words: quality-adjusted life years; discounting; time tradeoff; standard gamble; individual preferences. (Med Decis Making 1994;14:188-193)
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