IDENTIFYING THE CENTRAL SULCUS ON CT-SCAN AND MRI

Methods to directly and indirectly identify the central sulcus are pre sented. In the axial plan. direct method is remarkable but obviously r equires good visualization of the sulci in the central region. Sulci a re readily visible in 90% of the cases on CT scans and in 50% of the c ases on MRI. The method can also be applied when tumoral development e rases the cerebral sulci by direct lecture of the contralateral roland ic region and right-left transfer. Within the precision limits of the method, it can be considered that the central sulci are symmetrical. T he main signs are : the relative morphologies of the superior frontal sulcus and the precentral sulcus, the hook-shaped aspect of the middle part of the central sulcus, the internal end of the central sulcus pr ojection anteriorly to the pars marginalis, the bifid nature of the in ternal end of the posterior central sulcus contouring the pars margina lis. and the lesser thickness of the posterior central gyrus compared with die precentral gyrus. The indirect method is less precise and is used when the direct method is unsuccessful, The central sulcus is ide ntified on the sagittal images and, using the lateral view of the skul l as a reference image, the topographic information is transferred to the axial images.