No, not at all. Mostly because these tests to discover the brain structure of a patient requires physically sectioning the brain. It’s not something you can do to a living person.
Secondly, this is one possible explanation for why some people are trans. It does not preclude the possibility that there are other etiologies that lead to the same condition, that do not display the same symptoms.
Lastly, and I think this is the big one, someone “pretending” to be trans in America today makes about as much sense as someone “pretending” to be gay in the 1950s. It gets you absolutely no advantages, and opens you up to an enormous range of legal prejudice and potential violence. People who undergo transition almost never are able to keep their jobs. They rarely are able to find employment at the level they held it before they transitioned. The process can be hugely destructive to personal relationships, family relationships in particular.
Una got some stories about women she knows who went from six figure salaries as men, to street prostitution after they transistioned, lost their jobs, were divorced by their spouse, shunned by their children, and turned away from even the most menial employment. If, when one of these women died, someone were to slice up their brain to check for female structure, and they didn’t find any, would it make any sense at all - after everything they gave up and suffered through - to say they were “faking” it?
ETA: As always, ignore anything DerekMichaels has to say on the subject. He’s got absolutely no fucking clue what he’s talking about.