The Indianapolis-based drugmaker plans to make Amyvid available in parts of the European Union in the second quarter, after giving imaging centers time to prepare to receive orders. U.S. regulators approved Amyvid last spring.

The radioactive imaging agent binds to beta-amyloid plaques and causes them to show up on positron emission tomography, or PET, scans of a patient's brain. The presence of these plaques may help indicate that a patient with cognitive problems has Alzheimer's disease, although such a scan does not definitively show that.

Lilly said Tuesday that other neurological disorders, brain tumors and infections like HIV may cause the presence of plaque. It also can be found in older people with normal cognitive function.

The drugmaker has said Amyvid is one tool intended to help find the cause of a patient's cognitive decline, and it should be used in conjunction with a clinical exam. Doctors diagnose Alzheimer's disease by observing patients and administering physical and mental tests.

Researchers say the disease could be diagnosed sooner if they could detect the presence of amyloid plaques earlier.

Amyvid was developed by Avid Radiopharmaceuticals, which Eli Lilly bought for $300 million in 2010.

Alzheimer's disease is the most common form of dementia, a term for brain disorders that affect memory, judgment and other mental functions.

The European Committee for Medicinal Products for Human Use had recommended Amyvid's approval in October.

Lilly shares closed just shy of a 52-week high Tuesday, at $53.29 each.