Indicators of correct targeting in stereotactic biopsy of intracranial lesions.

Background: Confirmation of whether a stereotactic biopsy was performed in the correct site is usually dependent on the frozen section or on novel tumor-specific markers that are not widely available. Immediate postoperative computed tomography (CT) or magnetic resonance (MR) is routinely performed in our service after biopsy. In this retrospective study, we have carefully analyzed these images in an attempt to determine the presence of markers that indicate appropriate targeting. Methods: Medical records and neuroimages of patients who underwent stereotactic biopsy of intracranial lesions were reviewed. The following variables were assessed: age, sex, anatomopathology, lesion site, complications, diagnostic accuracy, and the presence of image markers. Results: Twenty-nine patients were included in this case series. About 96.6% of the biopsies were accurate according to the permanent section. Of the 86.2% of patients with intralesional pneumocephalus on the postoperative images, 51.7% additionally presented petechial hemorrhage. In 13.8% of the cases, no image markers were identified. Conclusion: This is the first report of intralesional pneumocephalus and petechial hemorrhage as indicators of appropriate targeting in stereotactic biopsy. In the majority of the cases, an immediate postoperative head CT, which is widely available, can estimate how adequate the targeting is. To use intralesional pneumocephalus/ petechial hemorrhages as not only postoperative but also as intraoperative markers of appropriate targeting, it is advised that the surgical wound should be temporarily closed and dressed after the biopsy so that the patient can undergo a CT/MR scan and be checked for the presence of theses markers before removing the stereotactic frame.