Fig. 1

Radiological imaging of the tumor in the pineal region in Case 1. a, b Gadolinium-enhanced T1-weighted magnetic resonance imaging (MRI) in Case 1 shows a well-defined tumor within the quadrigeminal cistern, compressing the dorsal part of the midbrain with resulting mild hydrocephalus (a, axial view, b sagittal view). The vein of Galen (white arrow) and splenium of the corpus callosum (white asterisk) are displaced upward and the pineal body cannot be identified. c, d Preoperative internal cerebral angiography (ICAG) shows occlusion of the vein of Galen and development of a large collateral venous channel (white arrowhead) on the right medial surface of the occipital lobe, draining into the superior sagittal sinus (c, right venous phase, d left venous phase)