To the Editor.—
The recent discussion1 of the value of magnetic resonance imaging (MRI) in multiple sclerosis that appeared in JAMA is somewhat misleading.
While it is undoubtedly true that MRI may reveal many more lesions than the enhanced computed tomographic (CT) scan, there are instances where a double-dose delayed enhanced CT scan has shown lesions that were not seen by either inversion recovery or spin echo.1 More important, however, is the fact that contrast enhancement of the CT scan gives information regarding activity of the disease process (in fact the only such evidence) that as yet MRI does not.2
The two procedures provide different types of data. One would hope that at some time in the future, MRI will be able to reflect the state of the blood-brain barrier and thus replace the enhanced CT scan.
The CT remains the only means for evaluating the effects
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