Phenotyping emphysema and airways disease: Clinical value of quantitative radiological techniques

Figure 1 The process of computed tomography scanning. X-rays are passed from the source through the subject laid on the table, and received by the detectors that rotate 360° around the patient. The reduction of the intensity of the XR beam passed through the subject is calculated as an attenuation co-efficient, which from all the slices is reformatted into a digital image.

Figure 2 Calculation of densitometric indices. Example of a density histogram, and how the area under the curve at a given threshold is calculated. In this figure, with a threshold of -910HU, 12% of the pixels are between -910 and -1000HU.

Figure 3 Airways disease measurements. Diagram to demonstrate various values calculated in assessing either the luminal or wall contribution to airway thickening.