Stator for a gas turbine including a stator structure having a continuous through-duct for a gas through-flow, a circumferential member, which is arranged at a radial distance from the stator structure and is operatively coupled to the stator structure, and at least one member for maintaining the distance between the stator structure and the circumferential member. The apparatus 26 includes an electric motor 28, a first drive train 30 and a second drive train 32. The comb has at least two branch connection plugs secured to a single fixing plate, and handle means for said fixing plate. For each of at least two particular sub-sections, the method then computes a statistical parameter regarding the image values of the particular sub-section.