You don't know that about Maria's case. The article does not say whether Maria had brain scans; and if she did, what they showed.
And, for that matter, you don't know that what you've asserted is true about Terri, either. All you have, in Terri's case, is the word of her so-called husband and his pro-euthanasia lawyer that the "cerebral cortex is virtually void of living tissue." (And what does "virtually" mean here, anyway?) I have not heard any doctor verify this.
For your statement to be believable, it would be necessary for new scans to be done, and interpreted by several independent doctors, not shills hired by Schiavo.
Even then, it's my understanding that doctors cannot be 100% sure of their interpretation of brain scans. It takes an autopsy for that -- and, hmmmmmmmmm, Schiavo has ordered that there be no autopsy upon Terri's death.
So it's not clear that these purported scans are "relevant," either. Maybe they could give some indication of whether Terri could be rehabiliated, or maybe not. What is the ethical reason for forbidding her parents to even try?
As for "relevance":
...Frank Tetto said doctors didn't believe at first that his daughter really smiled. The Tettos held their daughter's hand and she squeezed back. Doctors said that was a reflex rather than a sign of conscious behavior, said the Tettos...The Tettos said they had to convince doctors and insurance companies that their daughter would benefit from various kinds of therapy and come all the way out of a coma, and one day talk to them.
Substitute "the Schindlers" for "the Tettos," and "Michael Schiavo" for "insurance companies." Looks pretty relevant to me.