A method for designing a patient-customized EA or selecting an existing EA that fits the patient best includes segmenting shapes of SOIs of the cochlea in a pre-operative CT image using a shape model； defining a 3D curve of interest within the shape model of the SOIs as a sequence of points-； automatically transforming the defined 3D curve to the pre-operative CT image so as to obtain a structure curve in the cochlea； determining a length and curvatures of the structure curve at the sequence of points； and designing a patient-customized EA or selecting an existing EA based on the determined length and curvatures of the structure curve such that after the EA shape model, which estimates the resting state shape of the EA, is rigidly registered to the structure curve in the cochlea, the EA shape model has a registration error smaller than a preset value.
