Radiation Induced Bone Necrosis MRI

A 60 y o male with known case of Naso pharyngeal Carcinoma under Radiotherapy.

Now presents with severe neck pain, reduced neck movements. 

Here is MRI study of Cervical spine, Sagittal T1, T2 and STIR sections, Post Contrast Sagittal T1w images. 

This MRI study of Cervical spine shows:
Radiation Induced fatty marrow signal noted as diffuse high marrow signal on T1 involving cervical vertebrae confined to Radiation field which is an expected finding.
But the altered marrow signal, marrow edema involving Odontoid process of C2 with adjacent abnormal enhancing soft tissue is suggestive of Radiation Induced Osteonecrosis.
No cord compression.

In this case the history of Naso Pharyngeal Carcinoma and Radiotherapy is vital otherwise the case is likely to get confused with Infective etiology.

Osteoradionecrosis

Osteoradionecrosis refers to a severe delayed radiation-induced injury and is characterised by bone tissue necrosis and failure in healing.
There is some overlap with the term radiation osteitis.

Pathology is thought to be alteration in blood supply to the bone from microvascular damage limits the ability of tissues to adjust to normal wear and turnover, resulting in tissue breakdown

Usually large radiation doses are required for osteoradionecrosis to occur.

While it can involve any bone which is in an irradiation field, there are specific sites in which osteoradionecrosis is more commonly seen. These include mandible during radiation required to radically treat naso-oro-pharyngeal tumours, chest wall-shoulder-humerus-scapula, Spine and Bony pelvis.