Intra- and Inter-Rater Reliability of Processing Ultrasound Tissue Characterization Scans in Midportion Achilles Tendinopathy

Table 3

Intra-rater and inter-rater reliability for the processing of UTC scans in quantifying the structure of the Achilles tendon midportion (n = 50).

Echo-type	Intra-rater reliability			Inter-rater reliability
	ICC (95% CI)	SEM	MDC	ICC (95% CI)	SEM	MDC
Echo-type I%	0.98 (0.97–0.99)	1.7	4.7	0.99 (0.95–0.99)	1.2	3.3
Echo-type II%	0.97 (0.94–0.99)	0.9	2.5	0.98 (0.96–0.99)	0.7	2.1
Echo-type III%	0.98 (0.96–0.99)	1.3	3.6	0.99 (0.95–0.99)	0.9	2.6
Echo-type IV%	0.99 (0.97–0.99)	0.7	1.9	0.99 (0.99–1.00)	0.7	1.9
Echo-type I + II%	0.98 (0.96–0.99)	2.1	5.9	0.99 (0.97–1.00)	1.5	4.2
Echo-type III + IV%	0.99 (0.97–0.99)	1.5	4.2	0.98 (0.95–0.99)	2.2	6.0

Intra-rater and inter-rater reliability are calculated for echo-types I, II, III, and IV individually, and combined for aligned fibrillar structure (echo-types I + II) and disorganized tendon structure (echo-types III + IV). CI: confidence interval; ICC: intraclass correlation coefficient; MDC: minimal detectable change (%); SEM: standard error of measurement (%).