Human Transcranial Super Resolution Imaging

Transcranial ultrasound imaging in humans is challenging due to the significantly aberrating nature of the skull bone, which degrades the image and compromises the resolution. Here, we demonstrate the feasibility of human super-resolution transcranial imaging. A focused-wave, full-aperture emission at 2.5 MHz was used to image out-of-plane and in-plane 208μm sized targets (λ/3) at a depth of 68.5 mm. By correcting the skull's aberration, registration errors in the lateral and axial dimensions were reduced to as low as λ/8 and λ/3 respectively in the out-of-plane super resolved images. Phase correction improved microbubble detection sensitivity by a factor of 1.48. An in-plane tube with the same diameter was resolved even without applying a phase correction across a 30 mm lateral field. Further phase correcting reduced the axial registration error by approximately 3λ, improved the shape of the tube and increased sensitivity by a factor of 1.31. Using microbubble contrast agents at a clinically relevant concentration of 1.6 * 10 ⁶ bubbles/mL, it is shown that transcranial super-resolution imaging through a human skull is feasible with focused ultrasound, even without phase correcting. Phase correction further improved sensitivity and resolution. These findings imply the feasibility of super-resolution imaging in the in vivo human brain.