Table 3:

Mean and median of qualitative image scores in various CT protocols with either IR or FBP^a

	Tube Current 320 mAs		Tube Current 275 mAs		Tube Current 225 mAs
	IR	FBP	IR	FBP	IR	FBP
Non-Enhanced
Noise	1.2 (1)	1.6 (1.5), P = .003	1.6 (2)	1.9 (1.75), P = .001	2.0 (2)	2.5 (2.5), P < .0001
GM/WM	1.4 (1)	1.8 (2), P = .002	1.6 (1.5)	2.2 (2.25), P = .009	2.2 (2)	2.9 (3.0), P < .0001
SS	1.4 (1)	1.7 (2), P = .007	1.6 (2)	2.0 (2), P = .01	2.1 (2)	2.7 (3), P = .0006
PF	1.6 (2)	2.0 (2), P = .1	2.0 (2)	2.7 (2.5), P = .001	2.8 (3)	3.4 (3), P = .0002
DA	1.3 (1)	1.7 (2), P = .002	1.7 (2)	2.2 (2), P = .0005	2.2 (2)	2.8 (2.5), P < .0001
Contrast-Enhanced
Noise	1.2 (1)	1.4 (1.5), P = .02	1.4 (1)	1.8 (1.75), P = .003	2.1 (2)	2.5 (2.5), P = .0002
GM/WM	1.3 (1)	1.6 (2), P = .002	1.6 (1.5)	2.1 (2), P = .001	2.1 (2)	2.7 (3), P = .0004
SS	1.3 (1)	1.6 (2), P = .004	1.5 (1.75)	1.9 (2), P = .008	2.0 (2)	2.6 (3), P < .0001
PF	1.6 (2)	2.0 (2), P = .01	2.2 (2)	2.5 (2.5), P = .09	2.8 (3)	3.0 (3), P = .2
DA	1.2 (1)	1.8 (2), P = .007	1.6 (2)	2.0 (2), P = .008	2.1 (2)	2.6 (2.5), P = .0003

Note:—SS indicates subarachnoid space margins; PF, distinctness of posterior fossa contents; DA, overall diagnostic acceptability.
↵a Image-quality grading is provided for noise, GM-WM matter differentiation, sharpness of SS, PF, and overall DA. Median is in parentheses.