Semiautomatic Volumetry of Low Attenuation of Thoracic Aortic Plaques on Curved Planar Reformations Using MDCT Angiographic Data with 0.5 mm Collimation

Figure 3

Volume rendering images of thoracic aorta in a 67-year-old man with AAA and long-term hypertension. Predetermined attenuation ranges: 0~29 HU in orange (low attenuation), 30~69 HU in light green, 70~150 HU in dark green, 151~500 HU in light blue (mixture of blood and contrast material), and 501 HU~ in yellow (calcification).

(a) The ascending aorta. Scattered small plaques with light and dark green codes (arrowheads) are shown in a segmented ascending thoracic aorta (arrows). A 17.7 mm³ of the low-attenuation (0~29 HU) was measured. The volume of total noncalcified plaque in 0~149 HU is measured as 1841.8 mm³

(b) The aortic arch. Dense plaques with green codes (short arrows) and orange code in 0~29 HU (long arrows) are shown in the left anterior wall of a segmented arch. A 187.7 mm³ of the low attenuation is measured. The volume of total noncalcified plaque is measured as 5794.3 mm³. Note. Red color code indicates minus attenuation

(c) The upper descending aorta. Dense plaques with mixed codes of greens and orange (arrows) are shown in the left lateral wall of a segmented descending thoracic aorta. A 77.6 mm³ of the low attenuation in the plaques was measured. The volume of total noncalcified plaque is measured as 2790.9 mm³