Complications of Neck Radiation Therapy



Complications of Neck Radiation Therapy


Christine M. Glastonbury, MBBS





Key Facts


Terminology



  • Uncommon, unwanted side effects from radiation therapy (XRT) seen in small proportion of patients


Imaging



  • Potentially involves any radiated neck tissue



    • Excessive inflammation, tissue necrosis, or tumor induction


  • CT or MR may be complementary for detection and characterization of abnormality


  • CECT typically first-order examination; evaluates soft tissues and bones



    • Mucosal ulceration and fistulae, myositis, osteoradionecrosis, chondronecrosis


  • MR best for nervous system complications



    • Cerebral radionecrosis, myelopathy, brachial plexitis, cranial neuropathy


  • PET may be misleading; focal FDG uptake common


Top Differential Diagnoses



  • Recurrent tumor


  • Skull base or mandible-maxilla osteomyelitis


Pathology



  • XRT results in obstructive arteriopathy


  • Tissues less able to withstand additional stress


  • Infection, tumor recurrence, or biopsy may precipitate necrosis


Clinical Issues



  • Uncommon; ˜ 1% of patients receiving neck XRT


  • Most complications occur ≤ 2 years after XRT


  • May occur up to 5-8 years post XRT


  • Treatment is largely conservative


Diagnostic Checklist



  • Key differential is always residual/recurrent tumor


  • Look for solid enhancing mass






(Left) Axial T1 MR image in a patient treated a decade prior for nasopharyngeal carcinoma (NPC) with chemoXRT demonstrates an enlarged nasopharyngeal airway following necrosis of left lateral nasopharyngeal wall tissues image. (Right) Axial T2 MR image slightly more inferiorly at the oropharynx shows the left medial pterygoid muscle image to be hyperintense and smaller than the contralateral side, suggesting radiation-induced myositis and fibrosis. There is no mass or other imaging feature of tumor recurrence.






(Left) Axial bone CT image in the same patient shows frank destruction and “crumbling” of the lateral aspect of the sphenoid body, creating a sequestrum image. This is osteoradionecrosis (ORN) of the sphenoid bone. (Right) Axial T1 C+ FS MR image in the same patient reveals abnormal irregular enhancement of anteromedial left temporal lobe image, indicating cerebral radionecrosis. This case illustrates potential for radiation-induced complications involving multiple tissues in same field.



TERMINOLOGY


Definitions



  • Uncommon, unwanted side effects from radiation therapy (XRT) seen in small proportion of patients


IMAGING


General Features



  • Best diagnostic clue



    • No. 1 diagnostic feature, as this potentially involves any radiated tissue in neck and may be marked inflammation, tissue necrosis, or tumor induction



      • Tissue necrosis: Soft tissue, muscle, cartilage, bone, brain parenchyma


      • Marked inflammation: Brachial plexus, cervical cord, cranial nerves, muscles


      • Radiation arteriopathy: Carotid vessels


      • Tumor induction: Radiation-induced neoplasm


Imaging Recommendations



  • Best imaging tool



    • CT or MR may be used for detection and characterization of abnormality



      • Modalities often complementary, particularly for bone lesions


      • Solid enhancing mass raises concern for tumor recurrence


    • MR best for evaluation of nervous system complications


    • PET/CT often misleading in neck



      • Focal FDG uptake may be seen with necrosis


      • Probably due to accompanying infection/inflammatory response


      • Must interpret with CECT or MR


CT Findings

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Sep 20, 2016 | Posted by in HEAD & NECK IMAGING | Comments Off on Complications of Neck Radiation Therapy

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