A polyline tree representation of a coronary artery tree imaged in a volume data set is obtained, and its topology is extracted to give a topological representation indicating the relative positions of vessels in the tree. The gas supply valve itself may be magnetically operable. In an implementation, the marking mechanism of the device marks tissue based on an oxygen saturation measurement obtained by the device. The remote controlling part switches the display screen image displayed by the cloud service connecting part to the display screen image acquired by the information processing device.