Chi magazine made the revelation after an interview with Dr Franca Corfini Strata, the wife of Pavarotti's dietician.
"Luciano and Nicoletta told us together one day, when we were staying with them," Telegraph quoted her, as telling 'Chi'.
The magazine said the treatment had been extremely costly and this could be the reason for Pavarotti's debts of 12 million pounds with a local bank at the time of his death.
Multiple sclerosis causes weakness, muscle spasms, and difficulty in speaking, swallowing, seeing and acute pain.
However, according to Mantovani's pals she is suffering from relatively mild symptoms of the disease and is able to lead a normal life.
Mantovani, 37, has been treated for the disease at the Multiple Sclerosis Research Centre in New York for the last two years.
Mantovani's rep was unwilling to comment on the magazine.