Topography and identification of the inferior precentral sulcus in MR imaging

Sagittal MR imaging was used to investigate cerebral sulci bordering the functionally important areas on the lateral suprasylvian surface. The aim of the study was to identify characteristic relationships of the inferior precentral sulcus to nearby sulci and gyri. MR findings in 20 healthy volunteers were compared with those in 62 intact postmortem hemispheres. MR techniques are described for the direct identification of the anterior ascending ramus of the sylvian fissure and the inferior precentral sulcus. These sulci, which border Broca's area and the primary motor area, can be reliably identified with sagittal MR. Four different types of sulcus topography were recognized. Most frequently, the inferior precentral sulcus is the sulcus posterior to the anterior ascending sylvian ramus (95% in the MR study, 87% in the anatomic study). Occasionally, an additional sulcus is interposed (5%, 10%), or an ascending ramus is absent (0%, 3%). Identification of these landmarks is important for the exact preoperative localization of cortical lesions as well as for the intraoperative interpretation of individual sulcus patterns.