> Can a human reliably carefully study for hours on end imaging from screening tests
This is actually very common in radiology where some positions have shifts of 8-12 hours, where one isn't done until all the studies on the list have been read.
> think of a future world where whole-body MRI scanning for asymptomatic people becomes affordable and routine thanks to AI processing) and not miss subtle anomalies?
The bottleneck in MRI is not reading but instead the very long acquisition times paired with the unavailability of the expensive machinery.
If we charitably assume that you're thinking of CT scans, some studies on indiscriminate imaging indicate that most findings will be false positives: