Among the parameters that can be used to quantify emphysema, percentage of lung attenuation area under −950 HU, mean lung density and 15 percentile point for lung density are the most commonly used.
Both a decrease in mean lung density and the percentage of low attenuation area on expiratory CT have been used in various study and correlated with disease severity in COPD and asthma [ 15- 17].
Finally, while biodegradation processes are often used synonymously with the term "natural attenuation," the mass balance approach in this study suggests that hydrodynamic processes such as advective mixing and dispersion account for a much greater percentage of overall attenuation than biodegradation processes in this aquifer system.
The score in each lung field was calculated according to the percentage of low-attenuation areas (%LAA): score 0, %LAA <5%; score 1, %LAA ≥5%– < 25%; score 2, %LAA ≥25%– < 50%; score 3, %LAA ≥50%– < 75%; and score 4, %LAA ≥75%.
Analogously, s r C (t) and s v C (t) are the clean recto and verso text patterns at pixel t, channel C. The positive elements a nm C, n = (r,v) and m = (r,v), of the so-called mixing matrix A, represent the unknown percentage of ink intensity attenuation of the two texts in the two sides, due to ageing factors, or transparency of the paper or ink seeping from the back to the front page.
Thereafter, the percentage of change in attenuation from the pretreatment scan to the first evaluation during sunitinib was calculated for each patient.
The radiology core lab quantified the percent of emphysema in a lobe using the objective Density Mask method in which the percent of emphysema is defined as the percentage of voxels with attenuation values below a specified level in a given lobe.
We investigated whether percentages of high-attenuation areas (HAA%) and cystic areas (CA%) quantified from CT images were useful as indices of fibrotic IP.
The results were expressed as percentages of each subrange of attenuation as compared with the total lung area.
gain attenuation, whether represented in absolute grams or in percentage-of-initial or in body weight change in grams or in percentage-of-initial.
