1. A computer-implemented method of segmenting image data, comprising: accessing patient image data representative of a portion of a patient's internal anatomy containing an anatomical feature; accessing image data representative of a model of the anatomical feature, wherein the model of the anatomical feature comprises a plurality of internal structural features; aligning the model of the anatomical feature with a region of the patient image data corresponding to the anatomical feature; aligning each of the plurality of internal structural features with their corresponding internal structural feature in the patient image data; and. segmenting patient image data aligned with the model of the anatomical feature from patient image data not aligned with the model of the anatomical feature.