Interobserver and intraobserver variation of two-dimensional and three-dimensional anal endosonography in the evaluation of recurrent anal cancer

PURPOSE: This study was designed to evaluate the interobserver and intraobserver agreement of two-dimensional (2-D) and three-dimensional (3-D) anal endosonography for the detection of local recurrence anal carcinoma.

METHODS: Thirty-six patients were treated for anal carcinoma, and seven had recurrent disease. They were investigated by using 3-D endosonography at Rigshospitalet from July 2001 to January 2005 because of suspected local recurrence. The 3-D endosonographic examinations were reviewed from the hard disc by two observers who twice reviewed all 2-D examinations (the axial projection) as well as all 3-D examinations (the axial, as well as the reconstructed coronal and sagittal projections). The observers scored each examination according to the following scale regarding presence of local recurrence: 1 = no finding/benign findings; 2 = properly benign findings; 3 = suspicious findings/malignant findings. Kappa statistic-statistic was used to evaluate interobserver and intraobserver variation.

RESULTS: Three-dimensional endosonography achieved better interobserver agreement than 2-D endosonography: kappa 3-D 0.34-047 vs. kappa 2-D 0.15-0.28 and better intraobserver agreement: kappa 3-D 0.34-0.62 vs. kappa 2-D 0.22-0.28. These differences showed P < 0.05.

CONCLUSIONS: Three-dimensional endosonography proved to have significantly better interobserver and intraobserver agreement than 2-D endosonography concerning detection of recurrent anal cancer. Three-dimensional endosonography seems to be less dependent of the individual examiner than 2-D endosonography.