Table 1:

Subjective image quality rating (1 = worst, 5 = best) for brain structures and intracranial hemorrhage for filtered back-projection and 5 strengths (S1–S5) of sinogram-affirmed iterative reconstruction technique

Image Reconstruction Technique	Rating Brain Structures				Rating Intracranial Hemorrhage
	340 mAs		260 mAs		340 mAs		260 mAs
		κ		κ		κ		κ
FBP	2.8 ± 0.4	0.71	2.0 ± 0.8	0.59	2.5 ± 0.7	0.9	2.1 ± 0.8	0.67
S1	3.5 ± 0.6^a	0.71	2.9 ± 0.6^a	0.48	3.15 ± 0.8^c	0.85	2.8 ± 0.8^a^,^c	0.9
S2	4.4 ± 0.6	0.77	3.7 ± 0.7^a	0.51	3.8 ± 0.7^c	0.82	3.4 ± 0.7^c	0.75
S3	4.5 ± 0.5^c	0.47	4.7 ± 0.5^c	0.62	4.39 ± 0.7^c	0.80	4.0 ± 0.7^c	0.72
S4	3.2 ± 0.7^a^,^c	0.86	3.4 ± 1.0^a^,^c	0.55	4.65 ± 0.6^c	0.81	4.65 ± 0.5^c	0.61
S5	2.0 ± 0.7^b^,^c	0.64	2.5 ± 0.9^b^,^c	0.37	4.44 ± 0.7^c	0.81	4.68 ± 0.6^c	0.55

↵Note:—^a P > .05 when compared with standard FBP at 340 mAs;
↵b P > .05 when compared with FBP at 260 mAs;
↵c P > 0.1 when compared with the same image reconstruction technique at different tube current–time product.
Interobserver agreement (slight [κ < 0.3], moderate [κ = 0.3–0.7], good agreement [κ > 0.7]).