Using image J to document healing in ulcers of the foot in diabetes

The aim of the study was to assess the reliability of measuring the cross-sectional area of diabetic foot ulcers using Image J software. The inter- and intra-rater reliability of ulcer area measures were assessed using digital images of acetate tracings of ulcers of the foot affecting 31 participants in an off-loading randomised trial. Observations were made independently by five specialist podiatrists, one of whom was experienced in the use of Image J software and educated the other four in a single session. The mean (±SD) of the mean cross-sectional areas of the 31 ulcers determined independently by the five observers was 1386·7 (±22·7) mm² . The correlation between all pairs of observers was >0·99 (P < 0·001). There was no significant difference overall between the five observers (ANOVA F1.538; P = 0·165) and no difference between any two (paired samples test t = -0·787-1·396; P ≥ 0·088). The correlation between the areas determined by two observers on two occasions separated by not less than 1 week was very high (0·997 and 0·999; P < 0·001 and <0·001, respectively). The inter- and intra-reliability of the Image J software is very high, with no evidence of a difference either between or within observers. This technique should be considered for both research and clinical use in order to document changes in ulcer area.