Eli Lilly and Co. said U.S. regulators have delayed approval of Amyvid, its product to help detect Alzheimer’s disease.

The Food and Drug Administration said the company needed to create a training program to ensure brain scans are interpreted properly, Indianapolis-based Lilly said Friday in a statement.

Lilly acquired Amyvid in its $300 million purchase of Avid Radiopharmaceuticals Inc. in December. Outside advisers to the FDA voted in January against immediate approval of the imaging agent, unless Lilly established a training program. CEO John Lechleiter said earlier this month that he was confident of gaining U.S. regulatory approval and that Lilly aimed to resolve the FDA panel’s concerns in a few months.

“Lilly and Avid have been engaged in an active and ongoing dialogue with the FDA,” Wei-Li Shao, Lilly’s brand director for Amyvid, said in the prepared statement. “We remain confident in the data submission package for Amyvid.”

On Jan. 20, an advisory panel of outside experts told the FDA that Lilly’s treatment should be approved.

Amyloid plaques are protein deposits that fill the brains of Alzheimer’s disease patients. New York-based Pfizer Inc. and Lilly are among drug companies testing medicines that remove plaque from the brain or prevent buildup in hopes of slowing the progression of the disease.

Doctors have no way to detect Alzheimer’s disease plaques until a patient dies and an autopsy is performed. Amyvid is an injected radioactive drug that adheres to plaques in the brain. This allows the plaques to be seen on a living patient using three-dimensional scan known as positron emission tomography.

Lilly spokeswoman Stefanie Prodouz said she didn’t know how long it would take to address the FDA’s concerns.

“We arranging to be having a conversation with the FDA soon to determine exactly what it is the FDA wants us to address,” she said in a telephone interview Friday. “It looks like there doesn’t need to be new trials.”

Exactly what role amyloid plays in the disease is a matter of debate. A leading theory holds that amyloid fragments cause the disease by harming brain cells. A vocal minority of researchers, including the late Mark Smith of Case Western Reserve University, have argued that amyloid is not the cause of the disease. Several agents that target amyloid have failed in patient trials.

Last August, Eli Lilly said its experimental Alzheimer’s disease drug semagacestat did not slow disease progression in two patient studies. Lilly is running two final-stage trials of another drug, solanezumab, that works against .amyloid by a different mechanism.

Lilly shares increased 34 cents, or 1 percent, to $34.47 each in mid-morning trading