Image evaluation of head and neck after radiation therapy: iconographic assay.

1. Image evaluation of head and neck after radiation therapy: iconographic assay. Department of Radiology, São Paulo University, Medical School Radiology Institute-HCFMUSP PATRICIO, B.N.T. ; SANTOS, G.T.; GOMES, R.L.E.; CEVASCO, F.I.; DANIEL, M.M.; GEBRIM, E.M.M.S.

2. The main modalities of treatment for the malignant tumors of head and neck are surgery, surgery combined with radiotherapy, radiotherapy alone or combined with chemotherapy and the procedure is defined by clinical and histological parameters, extension of primary lesion and presence of metastasis. The radiation-induced changes may be subdivided into expected changes and complication of radiotherapy, being important the distinction of radiation-induced changes from recurrent or residual tumors, usual situation, however difficult in the radiological practice. INTRODUCTION

3. The expected changes are observed after three months, persisting habitually until two years after radiation therapy, also being able to persist indefinitely. Inflammatory edema and fibrosis of subcutaneous fat of the anterior neck, laryngeal and pharyngeal mucosa and salivary glands are frequently observed. Other expected changes are carotid arteries accelerated arteriosclerosis and replacement of erythropoietic tissue by fatty tissue into vertebral bodies. EXPECTED CHANGES

4. Inflammatory edema and fibrosis of subcutaneous fat. Thickening of laryngeal and pharyngeal mucosa. Heterogeneous enhancement of salivary glands. Replacement of erythropoietic tissue by fatty tissue into vertebral bodies. EXPECTED CHANGES Click on hyperlinks below to see specific slides

5. Bone necrosis. Chondronecrosis. Soft tissue necrosis and fistulization. Radiation-induced angiopathy. Cranial nerve paralysis. Development of new primary tumors. RADIOTHERAPY COMPLICATIONS Click on hyperlinks below to see specific slides

6. SOFT TISSUESEXPECTED CHANGES The most common radiation-induced change in superficial soft tissue is edema in the acute phase and fibrosis in the chronic phase. These findings are seen radiologically as skin thickening and increased attenuation / stranding of subcutanous fat. The same changes are observed in deep larynx soft tissue, thickening of epiglottis and supraglottic mucosa.

7. SOFT TISSUE CHANGES • Larynx carcinoma treated with surgery and radiotherapy. • CECT shows skin thickening and stranding of subcutaneous fat.

8. SOFT TISSUE CHANGES B A • Another patient treated with radiotherapy. • T1W MR (A) and T1WC+ MR (B) with decreased signal in cervical anterior subcutaneous fat, heterogeneous enhancement of right submandibular gland and thickening of supraglottic larynx.

9. PHARYNGEAL MUCOSALSPACE THICKENING • Facial spinocellular carcinoma treated with radiotherapy. • CECT shows impregnation of the pharyngeal mucosal space of oropharynx and nasophanrynx, representing actinic mucositis.

10. SUPRAGLOTTIC LARYNGEAL THICKENING A A A B B B • Before (A) and after (B) radiotherapy CECT show thickening of epiglottis, ariepiglottic folds, enhancement of mucosa and right submandibular gland, right small laryngocele (arrow) and left laryngeal cyst (arrow head).

11. FLUID/EDEMA IN THE RETROPHARYNGEAL / DANGER SPACE • CECT shows fluid or edema in the retropharyngeal /danger space.

12. SALIVARY GLANDS Very sensitive to radiation. Symptoms of mucositis occur 1-3 weeks from the onset of 1000-2000 cGy doses radiotherapy. High-dose radiation causes degeneration of acini with accompanying decreased function of the salivary glands. CT heterogeneous enhancement may be caused by increased vascular permeability or by an increased extracellular space because of a diminished numbers of acini. Later CTs show fatty replacement and involution.

13. SUBMANDIBULAR GLANDS A B • CECT before (A) and after radiotherapy (B) shows heterogeneous enhancement of right submandibular gland, skin thickening and stranding of subcutaneous fat.

14. PAROTID GLANDS A B • Same patient CECT before (A) and after radiotherapy (B) shows heterogeneous enhancement of parotid glands.

15. PAROTID GLANDS A B • CECT before (A) and three months later, during radiotherapy (B), show enlargement and heterogeneous enhancement of left parotid gland, skin thickening and stranding of subcutaneous fat. A B

16. Most common osseous abnormality seen on MRI after radiotherapy. Asymptomatic, appears as increased intensity of bone marrow on T1 weighted images. Has been seen in patients with low doses (as 800 cGy) and may be evident as soon as 2 weeks into high doses radiotherapy. FATTY REPLACEMENT OF BONE MARROW

17. FATTY REPLACEMENT OF BONE MARROW 1 2 3 4 • Two years follow up T1W MR show increased signal in cervical vertebrae.

18. LARYNGEAL OSTEOCHONDRONECROSIS Radiation-induced osteochondronecrosis is an uncommon complication of radiotherapy for laryngeal carcinoma. Reported frequency of 1-15%. Laryngitis and biopsy of irradiated larynx may induce irreversible infectious perichondritis or osteomyelitis, may lead to necrosis and laryngeal collapse. Other predisposing factors include short treatment times to achieve a specific dose, large fields, arteriosclerosis and chronic respiratory disease. Usually occurs during radiation therapy, but may occur months and years after treatment. CT: inflammatory swelling, ulcerations, sclerotic appearance of the involved cartilages, strap muscles abscess or fistula formation.

19. LARYNGEAL OSTEOCHONDRONECROSIS 1 2 3 • Right vocal cord carcinoma treated with radiotherapy. • Follow up CECT show progressive sclerosis of thyroid cartilage and deep ulceration containing gas.

20. LARYNGEAL OSTEOCHONDRONECROSIS 2004 2008 2009 • Follow up CECT show progressive sclerosis, deformity and fragmentation of cricoid cartilage.

21. PHARYNGEAL FISTULA • Usually occurs 2 years after irradiation of oropharyngeal tumors. • Mucosal atrophy and continued alcohol and tobacco consumption are predisposing factors. • CT shows ulceration, gas and fluid on soft tissues.

22. MASTIGATORSPACE FISTULA • CECT shows masticator space necrosis and oropharyngeal fistula.

23. DANGERSPACEFISTULA • CECT shows pharyngeal mucosal and retropharyngeal space necrosis and a fistula to retropharyngeal/danger space.

24. DANGERSPACEFISTULA • Same patient CECT(A) shows gas in the prevertebral space, lateral ventricles and cavum septum pellucidum. • Three months later CECT(B) shows ventriculitis and massive pneumocranium. B A A

25. FARINGOCUTANEOUSFISTULA A • CECT shows a transglottic infiltrative lesion (A). • CECT after laryngectomy and radiotherapy (B), shows two faringocutaneus fistulae. A B B

26. FARINGOCUTANEOUSFISTULA • Same patient, three-dimensional CT reconstruction, shows faringocutaneus fistulae (arrows).

27. NERVEPARALYSIS Because cranial nerves are highly resistant to radiation, paralysis is an uncommon finding. The mechanism is nerve compression by perineural radiation-induced fibrosis. Nerve lesions may occur within 2-7 years after radiotherapy The hypoglossal and recurrent laryngeal nerve are most commonly affected.

28. TONGUEDENERVATION • Left vocal cord carcinoma treated with radiotherapy and local surgery. • T2W and T1W MR show increased signal with mild hemiatrophy in the left side of the tongue.

29. VOCAL CORD PARALYSIS • Esophagus carcinoma treated with surgery and radiotherapy. • CECT shows paralysis ofleft vocal cord. • Left recurrent laryngeal nerve lesion due to compromise of anterior mediastinal and left superior lobe of the lung.

30. OSTEONECROSIS Occurs secondary to a combination of damage to the vascular supply as a direct injury to the osteoblasts and osteoclasts. Can occur at any time after radiotherapy. CT Focal areas of demineralization, disorganization of the trabecular pattern, cortical thickening and areas of sclerosis. Pathological fractures are often present. MRI Acute T1W images show decreased signal intensity with correspond increased signal on T2W, representing edema. Later Persists low signal on T1W images, whereas T2W show mixed signal intensity, corresponding to edema and fibrosis. With chronicity, focal areas of fat may be deposited with increased signal on T1W images.

31. VERTEBRALOSTEONECROSIS A A • Nasopharynx carcinoma. • Earlier (A) and later (B) CECT, during radiotherapy, show progressive thickening and enhancement of right retropharyngeal and prevertebral space, C1 cortical erosion and fluid on right paravertebral space. B B

32. MANDIBLEOSTEONECROSIS 08/08/2008 • Rinopharynx lymphoepitelioma treated with radiotherapy. • Follow up CECT show areas of sclerosis and demineralization surrounding the right second and third molar root. 05/29/2009 06/18/2009

33. OSTEONECROSISOFTHETEMPORALBONE • Oral carcinoma treated with radiotherapy. • NECT shows sclerosis and fluid in the right mastoid.

34. OSTEONECROSISOF THE TEMPORAL BONE • Another patient, T2W MR shows fluid in the right mastoid.

35. CAROTIDARTERYTROMBOSIS Therapeutic irradiation may accelerate atherosclerosis, increasing the risk of vascular stenosis or occlusion several to many years following radiation. However, intimal damage following irradiation may result earlier in thrombosis without stenosis.

36. COMMOM CAROTIDARTERYTROMBOSIS A A • Left vocal cord carcinoma treated with radiotherapy and local surgery. • T1W (A) and Fat-Sat T2W (B) MR show increased signal in the left common carotid artery without flow-void. A B

37. RADIATION INDUCEDNEOPLASIA • The most common radiation induced SNC tumor is meningeoma. • The most common bone tumor is sarcoma and soft tissue tumor is fibrous histiocytoma. • Other radiation-induced tumors are osteochondroma, thyroid gland tumors, schwannoma and osteoblastoma. • Post-radiation sarcoma of bone can arise within the treatment area either in previously normal bone or in previously affected bone. • There is a long latent period.

38. RADIATION INDUCEDNEOPLASIA • Some patients with retinoblastoma have higher prevalence of secondary tumors because of a genetic defect, however, the prevalence of osteosarcoma in the patients after radiotherapy is increased. • Bilateral retinobastoma treated with right globe enucleation and radiotherapy. CT demonstrates a mass in the right orbital wall, after 10 years of treatment.

39. CONCLUSION • Radiation therapy continues to play a central role as an effective therapeutic modality for a variety of adult and childhood malignancies. • Accurate interpretation of CT and MR studies in patients who undergo radiotherapy requires knowledge of expected radiographic changes. • Understanding of these alterations and their evolution may prevent misinterpretation of these changes as residual/recurrent tumor.

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