Vilanova needs more cancer treatment in USA
Vilanova, 44, will receive a "pioneering treatment" that was "proving particularly effective", Barca said on their website without giving further details.
"It was originally planned for this summer but as Barca has now clinched the league title it has been advanced to next week," they added.
Barca captain Carles Puyol will be presented with the league trophy after Sunday's match at home to Real Valladolid, the club's fourth title in five years.
Vilanova told a news conference on Saturday he and his players were targeting Real Madrid's record of 100 points set last season, which they can equal if they win their remaining three matches.
The host Valladolid on Sunday, play at city rivals Espanyol next weekend before Malaga's visit on the final matchday of the campaign.
"We have 91 points, which is already a lot," Vilanova said.
"We have the chance to get 100 and we will play to win in the three matches left.
"We can't let it slip now, that would be the only thing that I wouldn't like. We owe it to the fans and we have to finish the year well."