Post-treatment imaging appearances in head and neck cancer

Clinical information:
Histopathology:
TNM staging:
Surgery: Radical/ modified radical neck dissection, laser, no surgery
Reconstruction surgery: yes/ no
If yes, flap details:
Radiotherapy: yes/ no
If yes, type of radiotherapy

Primary site review:
Residual disease/ recurrence/ post-op change
Radiation induced sarcoma: latent period is 5 years, radiation induces SCC, lymphoma and meningioma

Post RT changes:
Acute post-RT changes (within 2-4 weeks): skin, platysma, neck space edema, enhancing salivary glands, enhancement of mucosal lining, increased attenuation of paralaryngeal fat
Subacute post-RT changes (few months to 18 months): chronic mucositis (polyps), chronic sialadenitis, i.e, loss of volume (virtually in ALL), especially parotids, fibrosis (may or may not enhance, stop enhancing after 18 months), persistent reactive nodes

Radionecrosis:
Sites: larynx, mandible, temporal bone, basisphenoid, maxillary bone
6- 15 months
Sclerosis, fragmentation, mottled appearance, sloughing, break of cartilage and bone with sequestration, pathological fracture, loss of trabeculae. Subluxation/ dislocation (of arytenoids). Soft tissue thickening, abscess, fistula, gas in the soft tissue. Enhancement of the adjacent muscles and fat.

Neurological changes:
Radiation cerebral necrosis: Deep white matter of medial and inferior temporal lobes or frontal lobes (depending on site of RT)
Brainstem encepahlopathy, myelopathy and transverse myelitis
RT induced brachial plexopathy
Traumatic neuroma
Denervation od V, XI and XII nerves

Reference:
Post-treatment imaging appearances in head and neck cancer patients

Vestibular schwannoma

85% of CP angle mass

90% from inferior division (superior division 6%) of vestibular nerve, within or near vestibular (Scarpa) ganglion, at porus acousticus, or just within IAC (near Obersteiner-Redlich zone = transition from glial cells to Schwann cells)

Surgerical approach:
Middle cranial fossa, translabyrinthine and suboccipital (retrosigmoid)

Reference:
http://radiographics.rsna.org/content/29/7/1955.abstract

Skull base foramen

Optic canal: Optic nerve
Superior orbital fissure: Nerves III, IV, V1 and VI, superior ophthalmic vein
Inferior orbital fissure:


Foramen ovale: Mandibular divison of trigeminal (V3)
Foramen rotundum: maxillary division of trigeminal (V2)
Foramen spinosum: Middle meningeal artery
Foramen lacerum: Meningeal branches of ascending pharyngeal artery
Vidian canal: Vidian artery and nerve
Stylomastoid foramen: exit of facial nerve
Hypoglossal canal: XII cranial nerve

IAC: VII and VIII cranial nerves

Jugular foramen/fossa: IX, X, XI cranial nerves, IJV
Carotid canal: ICA

Imaging cholesteatoma

Classification:

Congenital (2%)


Acquired (98%)


--Pars flaccida (82%)


--Pars tensa (18%)


---- Posterosuperior (78%)


---- Anteroinferior (22%)

Congenital cholesteatoma:

= Epidermoid Epithelial rest cells

Can be seen in middle ear, mastoid, squamous temporal, petrous apex, CP angle

Common in anterior middle ear cavity near ET tube and stepes

Acquired cholesteatoma:

= Prusaac's cholesteaoma, attic cholesteatoma

Sequele to middle ear infection

MRI:




Useful in evaluating post operative/ recurrent cholesteatomas; differentiating




Delayed post-Gd T1 SE is useful




Cholesterol granuloma: increased signal on T1, no change on delayed Gd T1, low signal on DWI


with b factor of 800 sec/mm².




Granulation tissue without recurrence: low signal on T1, high signal on T2, enhance on delayed


Gd T1, low signal on DWI b factor of 800 sec/mm²




Recurrent cholesteatoma: low signal on T1, no change on delayed Gd T1, and high signal on DWI


with b factor of 800 sec/mm²






Cholesteatoma shows increased signal on DWI, whereas granulation tissue, fibrous tissue, cholesterol granuloma, or serous fluid show low


signal intensity.






Reference:




http://radiology.rsnajnls.org/cgi/content/full/238/2/604




Diffusion-weighted MR Imaging Sequence in the Detection of Postoperative Recurrent Cholesteatoma


Radiology 2005;238:604-610

Imaging Neck

Approach to ultrasound of the neck