Fig. 3. Cerebral angiogram of Case 18. (A) A mask image of a vertebral angiogram (anterior–posterior working projection view) after the insertion of the first coil. (B) An illustration of the mask image (A) after the first coil insertion. (C) A mask image of a vertebral angiogram following the detachment of the first coil. (D) An illustration of the mask image (C) after the first coil detachment. The white arrows (A–D) indicates the first marker, the white arrowheads (A–D) points to the sub-marker, and the black arrowheads (C and D) shows the microcatheter shaft. Although the first marker on the microcatheter was obscured by the coil mass, the sub-marker and microcatheter shaft allowed verification that the microcatheter tip, initially on the left side of the aneurysm before coil detachment, had moved to the right side afterward.