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Fig 4. A, Conventional angiogram demonstrates a small right posterior communicating artery aneurysm after coil embolization. The unsubtracted image (left) depicts a tail of coil projecting anteriorly (arrow). The subtracted image (right) demonstrates that this coil tail projects toward the parent artery from which the aneurysm arises. A small amount of filling between the interstices of the coil mass is also noted along the anterior aspect of the aneurysm neck. B, Correlative TOF-MRA source image demonstrates the coil mass as a signal-intensity void. A linear signal-intensity void (arrow) projects anteriorly into the parent posterior communicating artery corresponding to the coil tail visualized on the native image. The small pocket of residual filling is also appreciated along the lateral aspect of the coil mass. Reading the MRA without the posttreatment angiographic correlation could lead to confusion with respect to the interpretation of these structures in the region of the aneurysm neck. A correlation of the 2 techniques provides a detailed and complimentary understanding of the anatomy in this region.
