In the weeks after Pope Francis blessed their ailing daughter during his visit to Philadelphia, Joe and Kristen Masciantonio probably spent more time in the cancer ward at Children's Hospital of Philadelphia than at Mass at St. Cyril of Jerusalem in Bucks County.

But last week, Joe said, scans showed that a troublesome tumor in 1-year-old Gianna's brain shrank significantly after rounds and rounds of surgeries and chemotherapy, to the point where it's "basically gone."

The girl's stunning reversal of fortune - following a dire diagnosis from her doctors - led one family friend to call Gianna's encounter with the pontiff "the Miracle on Market Street."

That same friend, Donny Asper, was the sympathetic FBI agent who tipped off the family that Pope Francis would pass the James A. Byrne U.S. Courthouse on Market Street near Seventh when leaving Independence Hall after his Sept. 26 address.

Her parents knew she needed help. Gianna, whose first birthday was that same month, had a rare brain tumor; she'd already gone through several chemotherapy sessions.

Initially, doctors were skeptical that anything could be done: The tumor was inoperable.

"They said go home, enjoy the last weeks, maybe months that you have with her," said her father, a 37-year-old graduate of St. Joseph's University.

But his wife had dreamed of Gianna meeting the pope weeks before it was announced that he would arrive in Philadelphia.

"She was just dead set," he said. "I'm the dad who didn't want to see the pope."

He was worried about the effect that a hectic day in public would have on his daughter's immune system, already weakened by the treatment. So they left it up to their doctor, who encouraged them to head down there.

They made it to the city from Warrington in 40 minutes, a record time. By the courthouse, they held little Gianna out as far as they could, while officers from the Philadelphia Police Department waved the Popemobile over.

"He just caught our eye . . . it's like God told him," Joe Masciantonio said Sunday.

Domenico Giani, head of security for Vatican City, brought Gianna over to Pope Francis, who kissed her on the head, right where her tumor was.

"It was truly blessed," her father said. "God really let her know he heard her prayers."

Uniformed law enforcement and military were cheering for Gianna after the convoy whisked the Holy Father away. Some teared up.

The family then joined hands in prayer with several FBI agents and the bureau's chaplain in Philadelphia, Monsignor Mike Mannion.

"Sometimes coincidence is God's way of remaining anonymous," Mannion said. "The fact that they were literally able to flag the pope down, he stopped and blessed the baby. . . . It's very special.

"I don't even know how to describe that feeling," Joe Masciantonio said. "The miracle is all the people who prayed. The pope is just the messenger that God heard."

brandtj@phillynews.com215-854-4890@JBrandt_TU