Table 2:

Quantitative assessment of image quality (N = 64 subjects)

	MBIR		ASiR		Difference (MBIR-ASiR)
	Mean	(95% CI)	Mean	(95% CI)	Mean	(95% CI)	P Valuea
Level 1 (angle of mandible)
Mean of IJV (HU)	130.3 ± 19.6	(125.4–135.1)	131.0 ± 19.2	(126.2–135.8)	−0.7 ± 2.7	(−1.4 to −0.1)	.030
Mean of SCM (HU)	62.9 ± 5.0	(61.7–64.2)	64.4 ± 4.9	(63.2–65.6)	−1.5 ± 2.2	(−2.0 to −0.9)	<.001
Mean of fat (HU)	−81.4 ± 23.2	(−87.2 to −75.6)	−77.1 ± 23.3	(−82.9 to −71.3)	−4.2 ± 8.1	(−6.3 to −2.2)	<.001
SD of IJV (HU)	6.3 ± 2.6	(5.7–7.0)	7.3 ± 2.0	(6.8–7.8)	−1.0 ± 1.9	(−1.5 to −0.6)	<.001
SD of SCM (HU)	6.6 ± 1.4	(6.3–7.0)	7.1 ± 1.6	(6.7–7.5)	−0.5 ± 1.5	(−0.8 to −0.1)	.020
SD of air (BN) (HU)	6.3 ± 9.2	(4.0–8.6)	7.8 ± 9.2	(5.5–10.1)	−1.5 ± 4.8	(−2.7 to −0.3)	.016
SNR of SCM	16.2 ± 7.2	(14.4–18.0)	12.1 ± 4.3	(11.0–13.2)	4.1 ± 5.7	(2.7–5.5)	<.001
CNR of IJV and SCM	7.6 ± 2.6	(7.0–8.3)	6.8 ± 2.4	(6.2–7.4)	0.9 ± 1.4	(0.5–1.2)	<.001
Lower level 2 (superior mediastinum)
Mean of SVC (HU)	119.8 ± 24.5	(113.7–125.9)	117.8 ± 23.7	(111.8–123.7)	2.0 ± 7.3	(0.2–3.9)	.030
Mean of PM (HU)	55.6 ± 11.0	(52.9–58.4)	53.3 ± 13.0	(50.1–56.5)	2.3 ± 7.9	(0.4–4.3)	.021
Mean of fat (HU)	−101.3 ± 19.4	(−106.2 to −96.5)	−98.9 ± 18.1	(−103.4 to −94.3)	−2.5 ± 7.7	(−4.4 to −0.6)	.012
SD of SVC (HU)	10.2 ± 4.5	(9.1–11.3)	13.7 ± 4.9	(12.5–14.9)	−3.5 ± 2.8	(−4.2 to −2.8)	<.001
SD of PM (HU)	8.5 ± 2.4	(7.9–9.1)	10.9 ± 2.9	(10.2–11.6)	−2.4 ± 3.0	(−3.2 to −1.7)	<.001
SD of air (BN) (HU)	32.1 ± 32.5	(23.9–40.2)	33.5 ± 30.5	(25.9–41.1)	−1.4 ± 23	(−7.1–4.2)	.61
SNR of PM	6.9 ± 8.1	(4.9–9.0)	3.9 ± 3.4	(3.0–4.7)	3.1 ± 6.4	(1.5–4.7)	<.001
CNR of SVC and PM	4.9 ± 2.0	(4.4–5.4)	3.7 ± 1.6	(3.3–4.1)	1.2 ± 1.3	(0.9–1.5)	<.001

Note:—IJV indicates internal jugular vein.

^aPaired t test.