The Short Version
The claim conflates two different study conditions. When radiologists were not told deepfakes were present, only 41% spontaneously flagged something unusual — but this measures unprompted suspicion, not detection accuracy. When explicitly told synthetic images were included (the standard controlled detection task), radiologists achieved 75% mean accuracy, well above the "fewer than half" threshold. The claim cherry-picks the lower figure and mischaracterizes it as a controlled detection result.