PMC

Intra and inter-observer ICC (denoted by filled diamond) for linear and semi-automated volumetric measurements with 95% confidence intervals displayed as high-low lines

Image of volumetric measurement being made with the Olea Sphere programme. The left VS is highlighted as the ROI (VS vestibular schwannoma, ROI region of interest)

MRI of left VS showing long axis of tumour at 40° angle to the horizontal when viewed in coronal plane (left image), with the obliquely reformatted axial image displayed on the right

a–d Display standard Bland–Altman plots for all four paired measurement sets to show levels of intra and inter-observer agreement for linear and semi-automated volumetric measurement techniques. These plot the difference between the values against the mean for each pair of measurements. The dashed line represents the overall mean of the differences between sets of measurements. The dotted lines are calculated as ± 1.96 × SD and represent the upper and lower limits of agreement