Role of MRI in Diagnosis of Brain Stem and Cervico­ Medullary Junction Lesions

Abstract

The signal intensity of MR images is dependent on three variables T 1 , T2 and proton density, unlike the signal variables in CT (attenuation coefficient)

MRI does not use any type of radiation and appears to be without hazards. The potential hazards which may exist, the effect of magnetic field on the pacemakers and the aneurysmal clips, this can be avoided as long as the precaution outline is observed.

The availability of direct sagittal and coronal imaging allows very accurate and rapid localizations of the spinal and cerebral pathology without the relatively high radiation dose extra-time involved in reformat information from the transverse sections as with CT.

In MRI there are no streaking artifacts which are often present in CT and which can degrade the quality of the image particularly in the posterior fossa.

However, MRI contrast agents may be useful in some cases especially when the examiner wants to define the border between the lesion and the associated edema (Kean and Smith, 1986).