Intra- and inter-observer variation of region-of-interest methods in quantitative clinical diffusion tensor imaging

Abstract

Diffusion tensor imaging (DTI) is widely used as both a scientific and clinical tool in the assessment of brain white matter integrity in various diseases. Two different region- of-interest (ROI) methods were compared by analysing their intra- and inter-observer variation. Participants were thirty healthy volunteers (mean age 37.8 years, range 18 - 60). Using 3 Tesla MRI and DTI of the brain, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated at five different anatomical locations of the pyramidal tract. Inter- and intra-reader repeatability and variations were determined by circular and freehand ROI methods. The values for intra-and inter-observer variation were below 15 % with both methods and the repeatability showed excellent or substantial agreement in 68 % of cases. The values varied considerably between the different anatomical regions. For FA, the highest intraclass correlation coefficient (ICC) value was found in the capsula interna by the circular method and in the corona radiata by the freehand method. For ADC, the highest ICC was in the basal pons with circular ROIs and the centrum semiovale with freehand ROIs. The inter-observer measurements also varied regionally. For FA and ADC, good ICC values were reached in the capsula interna and centrum semiovale with the circular method and the capsula interna and corona radiata with the freehand method. Variation of the intra- and inter-observer measurements was lowest in area of the capsula interna (CV% < 6.0). Variation and repeatability were similar by both ROI methods. The results varied between different regions. From a clinical point of view, the freehand method gave a better general impression of brain matter integrity. © 2011 Springer-Verlag Berlin Heidelberg.