Analysis of subgroups: To analyze statistical differences in diagnostic accuracy between modalities, we based the analyses on mathematical combinations and used the term "certainty" to refer to diagnostic accuracy that one imaging modality has over the other one; then we performed the meta-regression analysis for comparison of "certainty" between two imaging modalities at the same time. We used a graphic representation for the results. We did a post-hoc analysis by sub-groups to all other variables, common to every technique and/or specific for each imaging modality studied.