OpticChiasm
Model: HeadNeckBPlexus
Model Information
Metrics
Average Volume (cc)
Dice Coefficient
95th Percentile Hausdorff Distance (mm)
Median Distance to Conformity (mm)
Undercontouring MDC (mm)
Overcontouring MDC (mm)
Delineation Information
Guidelines
Taken from Eekers DBP, Di Perri D, Roelofs E, Postma A, Dijkstra J, Ajithkumar T, et al. Update of the EPTN atlas for CT- and MR-based contouring in Neuro-Oncology. Radiother Oncol 2021;160:259–65. https://doi.org/10.1016/j.radonc.2021.05.013.
Method
Manual The optic chiasm (14 mm transverse, 8 mm antero-posterior and 2–5 mm thick) is located 1 cm superior to the pituitary gland, which has high signal on T1 MRI, and just anterior to the pituitary stalk (located above the sella turcica). The lateral border is the internal carotid artery. The chiasm is superiorly located in the antero-inferior part of the third ventricle, below the supra-optic recess and above the infundibular recess of the third ventricle, with the optic nerves in front and the divergence of the optic tracts behind. The anterior cerebral arteries and the anterior communicating artery are located ventral to the chiasm.
Structure Boundaries
Cranial Boundary
supraoptic recess
Caudal Boundary
1 cm superior to the pituitary gland
Lateral Boundary
Internal carotid artery
Ventral Boundary
Optic nerves
Dorsal Boundary
Divergence of the optic tracts