X @tb_doc Contributors AA, GL, MM and WMR were involved in review of the imaging. AP drafted and revised the manuscript with input from AA, GL, MM and WMR. The images were reconstructed and captions written by AA. Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors. Competing interests None declared. Provenance and peer review Not commissioned; externally peer reviewed.
