Orbitofrontal Cortex

Orbitofrontal Cortex

The orbitofrontal cortex (OFC) is located on the underside of the frontal lobes, directly above the eye sockets. It is a key component of the brain networks involved in cognition, emotion, and behaviour. The OFC plays an important role in reward processing, decision-making, emotional regulation, learning from experience, and adapting behaviour in response to changing circumstances. It helps individuals evaluate outcomes, assess risk and reward, and make appropriate social and behavioural choices. Because of its central role in cognitive and emotional functioning, there is increasing interest in understanding the potential impact of radiation dose to the orbitofrontal cortex. Accurate delineation is therefore important for studies investigating treatment-related neurocognitive and behavioural outcomes, as well as for treatment planning strategies aimed at preserving brain function.

Co-registration with a T1-weighted MRI is recommended to facilitate accurate identification of the structure. The orbitofrontal cortex is most easily identified on coronal images approximately halfway through the frontal lobe, typically 3–4 cm posterior to the frontal pole.

Important anatomical landmarks:

• Medial border: the olfactory sulcus.
• Lateral border: the lateral orbital sulcus.

When moving anteriorly through the frontal lobe:

• The medial border follows the olfactory sulcus, excluding the gyrus rectus.
• Once the olfactory sulcus is no longer visible, the medial border extends to the midline.
• The lateral border follows the lateral orbital sulcus.
• After the lateral orbital sulcus disappears, the border continues along an imaginary horizontal line at the same level towards the frontal pole.

When moving posteriorly:

• The medial border continues to follow the olfactory sulcus.
• The lateral border gradually transitions from the lateral orbital sulcus to the circular sulcus of the insula.

Careful assessment in the coronal plane is recommended, as the anatomical boundaries of the orbitofrontal cortex can be challenging to appreciate on axial images alone.

The accompanying video demonstrates a step-by-step approach for identifying and contouring the orbitofrontal cortex using readily recognizable anatomical landmarks. This educational resource is intended to support consistent, accurate, and reproducible delineation for clinical and research applications.

Please site as follows:

Hofstede, D., Di Perri, D., Roelofs, E., Postma, A., Troost, E., & Eekers, D. EPTN International Neurological Contouring Atlas (INCA) instruction videos. CancerData, 2022. doi:10.17195/candat.2022.02.1