Delineation of radiation therapy target volumes for cutaneous malignancies involving the ophthalmic nerve (cranial nerve V-1) pathway.
OBJECTIVE
The ophthalmic nerve (cranial nerve V-1) runs in close proximity to the globe, optic nerve, chiasm, and brain. The purpose of this study was to provide contouring guidance using computed tomography (CT)-identifiable landmarks, based on an analysis of skin cancer patients with V-1 invasion.


METHODS
Radiation oncology planning CT scans were analyzed for landmarks to guide V-1 target delineation from the skin surface to the trigeminal ganglion. Axial and coronal magnetic resonance imaging (MRI) sequences were fused with the planning CT to confirm soft-tissue findings and identify enhancement related to perineural spread. CT/MRI-based anatomic landmarks were catalogued and described on an atlas.


RESULTS
Soft-tissue and bony landmarks were confirmed as consistently identifiable on CT with assistance from fused MRI. A reference atlas was developed that shows the entirety of the V-1 pathway on consecutive CT slices.


CONCLUSIONS
Initial delineation of the V-1 pathway can be accomplished using CT-visualized landmarks confirmed on fused MRI. This CT/MRI atlas will assist radiation oncologists in delineation of the V-1 pathway.
Department of Radiation Oncology, University of California, San Francisco, San Francisco, California.
Mekhail
M
Anwar
Department of Radiation Oncology, University of California, San Francisco, San Francisco, California.
Yao
Y
Yu
Department of Radiation Oncology, University of California, San Francisco, San Francisco, California; Department of Radiology, University of California, San Francisco, San Francisco, California; Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, San Francisco, California.
Christine M
CM
Glastonbury
Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, San Francisco, California.
Ivan H
IH
El-Sayed
Department of Radiation Oncology, University of California, San Francisco, San Francisco, California; Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, San Francisco, California. Electronic address: yoms@radonc.ucsf.edu.
Sue S
SS
Yom
D006258:Head and Neck Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D008279:Magnetic Resonance Imaging; D009361:Neoplasm Invasiveness; D009882:Ophthalmic Nerve / Q000000981:diagnostic imaging* / Q000473:pathology; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012878:Skin Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D014057:Tomography, X-Ray Computed