Cone beam CT-guided biopsy of a petrous apex lesion via the contralateral subzygomatic transclival approach.

Percutaneous biopsy of petrous apex lesions is technically challenging due to deep skull base anatomy and proximity to critical neurovascular structures.1-5 In this technical video 1, we present a cone beam CT-guided biopsy using a contralateral subzygomatic transclival approach, initially described under CT guidance.6 The minimally invasive route provides a safe, direct trajectory to the petrous apex while preserving the internal carotid artery. The step-by-step workflow includes cone beam CT-based trajectory planning, fluoroscopic guidance, and coaxial bone sampling using an 11-gauge biopsy needle. Two clinical cases are demonstrated: one revealing metastatic breast cancer and another confirming Erdheim-Chester disease. Both procedures were completed without complications and allowed definitive histopathological diagnosis. This approach expands the interventional neuroradiologist's toolkit for skull base access and represents a valuable alternative to open surgical biopsy in selected patients, combining precision, safety, and diagnostic efficacy. neurintsurg;18/3/893/V1F1V1Video 1Cases presentation.