MRI-based synthetic CT for assessment of the bony elements of the sacroiliac joints in children

Insights into Imaging

Table 4 Cohen’s kappa (%) for the categorical scoring for inter- and intra-reader reliability of synthetic CT (sCT) and CT

Measurement	For inter-reader reliability						For intra-reader reliability
Measurement	Kappa sCT (%)			Kappa CT (%)			Kappa sCT (%)			Kappa CT (%)
		Right side	Left side		Right side	Left side		Right side	Left side		Right side	Left side
Lumbosacral transitional anomaly:	100			100			100			100
Fusion of the growth plates of the sacrum S1/S2:	100			84.8			100			83.9
Fusion of the growth plates of the sacrum S2/S3:	84.8			70.6			100			70.6
Cortical delineation of the joint space of the iliac side:		100^a	100^a		100^a	100^a		100^a	100^a		100^a	100^a
Cortical delineation of the joint space of the sacral side:		100^a	0		100^a	100^a		100^a	100^a		100^a	100^a
Joint facet defect (≥ 3 mm) on the iliac side:		100^a	61.5		100^a	100		100^a	61.5		100^a	100
Joint facet defect (≥ 3 mm) on the sacral:		100^a	100^a		100^a	100^a		100^a	100^a		100^a	100
Presence of ossified nuclei of the SI joint:		83.1	83.1		67.2	100		100	100		65.5	100
Bony bridges of the SI joint:		0	61.5		100^a	100^a		100^a	61.5		100^a	100^a

Abbreviations: sCT synthetic CT, S sacral, SI joint sacroiliac joint
^a100% perfect agreement between the readers, kappa could not be calculated because of lack of variability