Table 6.

Interobserver agreement on qualitative image quality and diagnosis

	Standard-dose CT	Low-dose CT
Qualitative image qualitya
Subjective image noise	0.930 (0.901–0.951)	0.891 (0.847–0.922)
Image sharpness
Cortex & trabecular bone	0.896 (0.810–0.957)	0.880 (0.815–0.952)
Intervertebral foramina, joints and pedicles	0.912 (0.875–0.938)	0.776 (0.714–0.840)
Spinous and transverse process	0.985 (0.979–0.989)	0.810 (0.734–0.865)
Disc & end plate of vertebra	0.892 (0.847–0.924)	0.849 (0.793–0.890)
Adjacent soft tissue	1.0 (NA)	0.916 (0.884–0.938)
Sacro-iliac joints	0.959 (0.942–0.971)	0.877 (0.831–0.910)
Abdominal structures	0.983 (0.976–0.988)	0.880 (0.835–0.912)
Diagnostic acceptability	0.930 (0.901–0.951)	0.868 (0.819–0.904)
Diagnosis
R1 vs R2	0.938 (0.853–0.971)	0.845 (0.674–1.000)
R1 vs Reference standard	0.909 (0.808–0.967)	0.802 (0.614–0.990)
R2 vs Reference standard	0.971 (0.914–1.000)	0.858 (0.700–1.000)

Data are intraclass correlation coefficients (qualitative image quality) or kappa values (diagnosis) and 95% confidence interval in parenthesis. NA, not applicable; R1, reviewer 1; R2, reviewer 2.

^aAgreement between reviewer 1 and reviewer 2.