13 March 2006 CT acquisition technique and quantitative analysis of the lung parenchyma: variability and corrections
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Abstract
The fraction of lung voxels below a pixel value "cut-off" has been correlated with pathologic estimates of emphysema. We performed a "standard" quantitative CT (QCT) lung analysis using a -950 HU cut-off to determine the volume fraction of emphysema (below the cut-off) and a "corrected" QCT analysis after removing small group (5 and 10 pixels) of connected pixels ("blobs") below the cut-off. CT examinations two dataset of 15 subjects each with a range of visible emphysema and pulmonary obstruction were acquired at "low-dose and conventional dose reconstructed using a high-spatial frequency kernel at 2.5 mm section thickness for the same subject. The "blob" size (i.e., connected-pixels) removed was inversely related to the computed fraction of emphysema. The slopes of emphysema fraction versus blob size were 0.013, 0.009, and 0.005 for subjects with both no emphysema and no pulmonary obstruction, moderate emphysema and pulmonary obstruction, and severe emphysema and severe pulmonary obstruction, respectively. The slopes of emphysema fraction versus blob size were 0.008 and 0.006 for low-dose and conventional CT examinations, respectively. The small blobs of pixels removed are most likely CT image artifacts and do not represent actual emphysema. The magnitude of the blob correction was appropriately associated with COPD severity. The blob correction appears to be applicable to QCT analysis in low-dose and conventional CT exams.
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Bin Zheng, Bin Zheng, J. Ken Leader, J. Ken Leader, Harvey O. Coxson, Harvey O. Coxson, Frank C. Scuirba, Frank C. Scuirba, Carl R. Fuhrman, Carl R. Fuhrman, Arzu Balkan, Arzu Balkan, Joel L. Weissfeld, Joel L. Weissfeld, Glenn S. Maitz, Glenn S. Maitz, David Gur, David Gur, } "CT acquisition technique and quantitative analysis of the lung parenchyma: variability and corrections", Proc. SPIE 6143, Medical Imaging 2006: Physiology, Function, and Structure from Medical Images, 61432S (13 March 2006); doi: 10.1117/12.654532; https://doi.org/10.1117/12.654532
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