[Size of acoustic neurinomas assessed by CT and magnetic resonance scanning].

Some acoustic neuromas do not grow or grow very slowly. It is therefore of value to compare the results of measuring the size of acoustic neuromas by either CT or Magnetic Resonance Imaging (MRI) scanning with a view to being able to observe the growth rate of these tumours. Fifteen patients with acoustic neuromas had both CT- and MRI-scans performed. Two trained radiologists evaluated the size of the tumours in a blinded fashion. There was a significant difference between one observer's calculations from the CT- and the MRI-scans, and also a significant difference between the two observers' calculations from the CT-scans. No difference in calculating tumour size was found between the two observers' calculations from the MRI-scans. It is concluded that the size of acoustic neuromas i evaluated more equally by two observers using MRI-scans than when using CT-scans. By the use of repeated MRI-scanning it is possible to keep patients with acoustic nouromas under observation and avoid operation in those patients where the tumour does not grow.