Table 5.

Intrarater agreement of two readings stratified across two raters.

1st Rating	2nd Rating	Level of Agreement	Cohen’s kappa *	95% Lower CI	95% Upper CI	z-Statistic	p-Value
Rater 1
Black Hole	Black Hole	100%	1.00	1.00	1.00	21.75	<0.001
Island Sign	Island Sign	97.9%	0.94	0.91	0.98	20.50	<0.001
Hypodensities	Hypodensities	97.3%	0.93	0.90	0.97	20.34	<0.001
Spot Sign	Spot Sign	99.2%	0.96	0.92	1.00	20.92	<0.001
Blend Sign	Blend Sign	96.0%	0.85	0.78	0.91	18.44	<0.001
Rater 2
Black Hole	Black Hole	99.4%	0.98	0.97	1.00	21.40	<0.001
Island Sign	Island Sign	98.5%	0.96	0.93	0.99	20.93	<0.001
Hypodensities	Hypodensities	98.3%	0.96	0.93	0.99	20.91	<0.001
Spot Sign	Spot Sign	98.9%	0.95	0.91	0.99	20.77	<0.001
Blend Sign	Blend Sign	97.0%	0.89	0.83	0.95	19.33	<0.001

Legend: Intrarater agreement of four noncontrast computed tomography imaging signs and spot sign on computed tomography angiography specified with percentage agreement and stratified kappa with 95% confidence interval (CI). * stratified Cohen’s kappa across one rater in two ratings.