It's possible it scanned his brainwaves or whatever in that time
Exactly. Scanning for brainwaves was dead easy in late 24th century already in UFP... and ships internal sensors would likely be able to provide same if not better amount of information than a medical tricorder for that matter.
In short, the onboard sensors are so powerful and accurate, that computers can extrapolate data even based on incomplete analysis... and it would still be extremely (or mostly) accurate.