The FDA has approved the second imaging agent that can be used to detect a toxic protein found clustered in the fogged brains of Alzheimer's patients, but there's no guarantee it will ever find much of a market. The agency approved GE Healthcare's ($GE) Vizamyl (flutemetamol F18 injection), saying that doctors can use it to rule out Alzheimer's if the telltale clusters of beta amyloid are absent. But as the FDA's release notes, it can't be used alone to diagnose the disease--at least until more is known about the role that amyloid plays. Nor does it replace any of the current diagnostic tools now in place. Story