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.

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

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

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

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Bone necrosis. Chondronecrosis. Soft tissue necrosis and fistulization. Radiation-induced angiopathy. Cranial nerve paralysis. Development of new primary tumors.

RADIOTHERAPY COMPLICATIONS

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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.

SOFT TISSUE CHANGES

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

SOFT TISSUE CHANGES

• 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.

A B

PHARYNGEAL MUCOSALSPACE THICKENING

• Facial spinocellular carcinoma treated with radiotherapy.• CECT shows impregnation of the pharyngeal mucosal space of oropharynx and nasophanrynx,

representing actinic mucositis.

SUPRAGLOTTIC LARYNGEAL THICKENING

• 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).

A

B

AA

BB

FLUID/EDEMA IN THE RETROPHARYNGEAL / DANGER SPACE

• CECT shows fluid or edema in the retropharyngeal /danger space.

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.

SUBMANDIBULAR GLANDS

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

A B

PAROTID GLANDS

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

A B

PAROTID GLANDS• 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

B

A

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 REPLACEMENTOF BONE MARROW

• Two years follow up T1W MR show increased signal in cervical vertebrae.

FATTY REPLACEMENTOF BONE MARROW

2

4

1

3

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.

LARYNGEALOSTEOCHONDRONECROSIS

• Right vocal cord carcinoma treated with radiotherapy.• Follow up CECT show progressive sclerosis of thyroid cartilage and deep ulceration containing gas.

LARYNGEALOSTEOCHONDRONECROSIS

1

2

3

• Follow up CECT show progressive sclerosis, deformity and fragmentation of cricoid cartilage.

LARYNGEALOSTEOCHONDRONECROSIS

2004

2009

2008

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.

PHARYNGEAL FISTULA

MASTIGATORSPACE FISTULA

• CECT shows masticator space necrosis and oropharyngeal fistula.

DANGER SPACE FISTULA

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

DANGER SPACE FISTULA

• 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.

A

A

B

FARINGOCUTANEOUS FISTULA

• CECT shows a transglottic infiltrative lesion (A).

• CECT after laryngectomy and radiotherapy (B), shows two faringocutaneus fistulae.

BB

AA

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

FARINGOCUTANEOUS FISTULA

NERVE PARALYSIS

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.

TONGUE DENERVATION

• 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.

VOCAL CORD PARALYSIS

• Esophagus carcinoma treated with surgery and radiotherapy.• CECT shows paralysis of left vocal cord.• Left recurrent laryngeal nerve lesion due to compromise of

anterior mediastinal and left superior lobe of the lung.

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.

VERTEBRAL OSTEONECROSIS

• 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.

A A

B B

MANDIBLE OSTEONECROSIS

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.

06/18/2009

05/29/2009

OSTEONECROSISOF THE TEMPORAL BONE

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

• Another patient, T2W MR shows fluid in the right mastoid.

OSTEONECROSISOF THE TEMPORAL BONE

CAROTID ARTERY TROMBOSIS

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.

COMMOM CAROTID ARTERY TROMBOSIS

• 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

BA

A

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.

RADIATION INDUCEDNEOPLASIA

RADIATION INDUCEDNEOPLASIA

• Bilateral retinobastoma treated with right globe enucleation and radiotherapy. CT demonstrates a mass in the right orbital wall, after 10 years of treatment.

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.

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.

CONCLUSION

Becker M, Schroth G, Zbaren P, et al. Long-term changes induced by high-dose irradiation of the head and neck region: imaging findings. Radiographics 1997;17:5–26.

S.K. Mukherji, A.A. Mancuso, I.M. Kotzur et al., Radiologic appearance of the irradiated larynx. Part 1. Expected changes. Radiology 193 (1994), pp. 141–148.

S.K. Mukherji, A.A. Mancuso, I.M. Kotzur et al., Radiologic appearance of the irradiated larynx. Part 2. Primary site response. Radiology 193 (1994), pp. 149–154.

B.M. Rabin, J.R. Meyer, J.W. Berlin, M.H. Marymount, P.S. Palka and E.J. Russell , Radiation-induced changes in the central nervous system and head and neck. Radiographics 16 (1996), pp. 1055–1072.

J.A. Castelijns, M.W.M. van den Brekel, H. Tobi et al., Laryngeal carcinoma after radiation therapy: correlation of abnormal MR imaging signal patterns in laryngeal cartilage with the risk of recurrence. Radiology 198 (1996), pp. 151–155.

REFERENCES