Received: 22 June 2018
Accepted: 17 October 2018
First Online: 19 December 2018
Ethics approval and consent to participate
: The data used in this study were approved by the Research Ethics Committees from the various original studies used in this retrospective analysis and written informed consent was provided by all subjects.
: Consent to publish obtained in the written informed consent forms.
: XG declares that he is CEO, holds shares, and receives payment from Gold Standard Phantoms Limited. All the other authors declare that they have no competing interests.
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