How likely a CT scan with contrast would miss diagnosing acoustic neuroma?

My friend has almost all symptoms of it. But a CT scan did not show tumor. Should she take an MRT?
She has long history of vertigo, and is told by her ENT to have meniere. A couple of years ago she consulted a specialist, who said to her that she did not have meniere, but then she did not ask why the doctor thought so. Recently, about 10 months, her vertigo if getting worse, and lost hearing (one ear), so that's why she had the CT. Besides the worsening of usual vertigo symptoms she developed headache, in the back of head, and now so easily getting dizzy (if head moves even a bit).