The government will let patients receiving

Johnson & Johnson's

(JNJ) - Get Report

Cypher drug-coated stent undergo immediate magnetic resonance imaging.

Previously, patients had to wait two months after the stent was inserted to take an MRI exam. Holding the exam sooner can help doctors keep a closer eye on stent patients' health.

Wednesday's action by the Food and Drug Administration comes two weeks after the FDA granted similar approval to

Boston Scientific

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for its competing Taxus drug-coated stent.

The Cypher stent, made by J&J's

Cordis

unit, had to undergo lab tests to ensure that the stainless steel Cypher wasn't affected by the magnetic fields of the MRI.

Drug-coated stents are tube-like devices inserted into arteries to improve the flow of blood after artery-clogging plaque has been cleared. These stents periodically release a chemical into the arteries to help reduce the rate of reclogging. Drug-coated stents do a better job of reducing that risk than do uncoated ones.

On Wednesday, J&J fell 49 cents to $68.56.