-For HoloLens2, use our new app "MR puncture". For HoloLens1, use this app. - MR Needle Guide is an application which guides needle insertion using HoloLens2 (for research purposes, for free). It assists three-dimensional needle puncture by placing a 3D virtual protractor at any location and angle against the CT plane. The XYZ-axes, 3D virtual protractor, needle trajectory, and target, can be placed by manually, using QR code scan, tap to place, or the coordinate systems obtained from CT images. In HoloLens1, some functions including QR code scan cannot be used.