Freehand Ultrafast Doppler Ultrasound Imaging With Optical Tracking Allows for Detailed 3D Reconstruction of Blood Flow in the Human Brain

Ultrafast Doppler ultrasound imaging allows for detailed images of blood flow inside the brain during neurosurgical interventions. In this work, we extend this new imaging technique to geometrically accurate volumetric reconstructions using freehand 2D ultrafast ultrasound acquisitions in conjunction with optical position tracking. We show how the Doppler signal can be derived from a moving freehand ultrasound scan. These filtered 2D images are subsequently mapped onto a shared 3D reference space using a normalized convolution function. The proposed methodology allows for highly detailed volumetric reconstructions of cerebral and tumor blood flow. The dense vascular networks show intriguing blood vessel morphology with vessels down to several hundred micrometers in diameter. By adding patient-co-registered volumetric reconstruction to ultrafast Doppler ultrasound, we have created a 3D intra-operative imaging technique that is unmatched in terms of resolution, ease of use, and visualization capabilities.