Head and Neck ImagingOsteoradionecrosis
rare complication of
radiotherapy in the head and neck region. Osteoradionecrosis is a late complication, usually appearing months to years after the end of radiation treatment. Several risk factors have been identified, including high radiation doses and large radiation fields. Osteoradionecrosis may involve the
mandible, the ossified
cartilage of the larynx, the
temporal bone and the hyoid bone. The pathogenesis is not fully understood. A popular theory is that irradiation produces hypoxic, hypocellular and hypovascular tissue, unable to remodel following tissue loss, thus leading to breakdown.
Trauma is often associated with the appearance of osteoradionecrosis as it creates a demand for tissue repair beyond the capabilities of the irradiated tissue. The radiological findings include bony abnormalities (cortical interruptions and loss of spongiosa trabeculation), sequestration,
pathological fractures, soft tissue thickening (sometimes gas-containing), and fistula formation (
Fig.1). Differentiation from
tumour recurrence may be difficult. Also, see
chondronecrosis laryngeal.
RH
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Axial contrast-enhanced CT images. Patient irradiated 4 years earlier for left-sided squamous cell carcinoma of the floor of the mouth. High resolution bone window (a) and soft tissue window (b). Pathological fracture on the left side, with broad interruption of the lingual and buccal cortex. There is thickening and enhancement of the surrounding soft tissues. Note similar type of bone destruction on the opposite side (resorption of the spongiosa trabeculae and destruction of the buccal cortex); there was no soft tissue enhancement on the right side (from: Hermans R., Fossion E., Ioannides C., Ghekiere J., Van den Bogaert W., Baert A.L.: CT findings in osteoradionecrosis of the mandible. Skelet Radiol 1996, 25: 31-36, with permission).
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Osteoradionecrosis, Fig.1 (a) | | Osteoradionecrosis, Fig.1 (b) | |