Information processing apparatus, ultrasound endoscope, information processing method, and program

An endoscope system comprising:

• an ultrasound endoscope, and
• an information processing apparatus comprising a processor, wherein the processor is configured to:
• acquire an actual ultrasound image generated as an image showing an aspect of an observation target region including a specific part on the basis of reflected waves obtained by emitting ultrasonic waves from the ultrasound endoscope to the observation target region,
• acquire a virtual ultrasound image group including a plurality of virtual ultrasound images, each virtual ultrasound image virtually showing the aspect of the observation target region on the basis of volume data indicating the observation target region, the volume data being obtained by imaging a subject by a modality, wherein metadata is given to each virtual ultrasound image in the virtual ultrasound image group, and the metadata includes three-dimensional coordinates and an angle around a luminal-organ pathway,
• specify a positional relationship between a first position where the ultrasound endoscope is present and a second position where the specific part is present, for enhancing accuracy of movement of the ultrasound endoscope, by:
• selecting, from the virtual ultrasound image group, a first virtual ultrasound image whose rate of match with the actual ultrasound image is equal to or greater than a predetermined value,
• acquiring, as metadata of the first position, metadata given to the selected first virtual ultrasound image,
• identifying, from the virtual ultrasound image group, a second virtual ultrasound image corresponding to a target position of the specific part,
• acquiring, as metadata of the second position, metadata given to the identified second virtual ultrasound image,
• and comparing the metadata of the first position and the metadata of the second position,
• perform a first presentation process of presenting, on a display, the first position toward the second position in a direction that shortens a distance between the first position and the second position, on the basis of the positional relationship, and
• guide the ultrasound endoscope from the first position toward the second position on the basis of the positional relationship.