Optic Disc Drusen (Pseudo-papilledema)

A 22-year-old woman is referred for evaluation of bilateral "swollen optic discs" found incidentally on routine examination. She is completely asymptomatic with normal visual acuity (20/20), normal color vision, and no relative afferent pupillary defect. Fundus examination reveals bilateral lumpy elevation of the optic discs with blurred margins, absent physiologic cups, and anomalous retinal vessel branching. The structure marked **B** in the diagram—calcified drusen at the disc margin—is visible as glistening globular bodies. B-scan ocular ultrasonography is performed. Which finding on B-scan would MOST reliably confirm the diagnosis of optic disc drusen and exclude true papilledema?