2. In patients with head and neck cancer, posttreatment imaging can
be complicated and difficult to interpret because of the complexity
of the surgical procedures performed and the postirradiation
changes, but such imaging is critical for the evaluation of
(a)the response to therapy and
(b)tumor control.
Posttreatment changes are affected by the type of surgery
performed, reconstruction, neck dissection and radiation therapy.
4. In general, the management of early-stage head and neck
cancer consists of single-modality treatment with either
radiation therapy or surgery.
For locally advanced head and neck cancer (stage III or IV)
without distant metastases, multimodality treatment consisting
of a combination of curative surgery followed by adjuvant
radiation therapy, with or without chemotherapy.
5. Surgery with or without Reconstruction
Curative resection requires a wide local excision to obtain negative
surgical margins.
Reconstructive techniques are mainly classified into three types of
flap reconstruction.
1- Local flap reconstruction involves a geometric repositioning of
adjacent tissue.
2- Pedicle flap reconstruction involves rotation of donor tissue to
cover a defect, with preservation of the original arterial and
venous systems.
3- Free flap reconstructive technique involves the transfer of
tissue that is vascularized by local vessels, with anastomosis to the
tissue defect by using microvascular techniques.
6. Depending on their tissue components, flaps are divided into:
1. Simple flap consists of one tissue type, such as skin or
subcutaneous tissues.
2. Composite flap consists of more than one tissue, for example,
myocutaneous, fasciocutaneous, free jejunal interposition and
osseous flaps.
The more common types of free flaps used are the rectus abdominis
myocutaneous free flap, radial forearm free flap, lateral arm flap,
anterior lateral thigh flap, iliac crest flap, fibula free flap and jejunal
free flap.
7. Myocutaneous flaps are initially depicted as a mass with soft-
tissue attenuation representing muscle.
8. These flaps will gradually show denervation atrophy, which
causes volume loss and fatty replacement of the muscle.
9. Sharp boundaries exist between the flap and the adjacent normal
structures, which is an important sign indicating benignity.
It is therefore important to assess the superior and inferior
margins of the flap, where local recurrence most commonly
occurs.
Myocutaneous flaps show a wide spectrum of enhancement
ranging from almost no contrast enhancement to diffuse intense
enhancement.
10. Neck Dissection
The three major types of neck dissection are;
1- Radical neck dissection involves the removal en bloc of all of the
ipsilateral lymph nodes (levels I–V), including the
sternocleidomastoid muscle, IJV, SMG and spinal accessory nerve.
2- Modified radical neck dissection is the same as radical neck
dissection but with preservation of one or more of the following
structures: the sternocleidomastoid muscle, IJV, SMG or spinal
accessory nerve.
3- Selective neck dissection has four common subtypes: the
supraomohyoid type (levels I–III), the lateral type (levels II–IV), the
posterolateral type (levels II–V) and the anterior compartment type
(levels VI and VII).
11. The main CT and MR finding after neck dissection is the absence
of the tissues resected with the cervical lymph nodes.
Another CT finding is an area of soft-tissue attenuation
surrounding the carotid sheath completely.
At MR imaging, the postoperative area shows low to intermediate
signal intensity on T1- and T2- weighted MR images, a finding that
represents fibrosis or scar.
Fat planes are obliterated, which makes the identification of
nodal recurrence more difficult.
12. Normal appearance after neck dissection for right cervical lymph node metastases of
unknown primary cancer.
A right-sided radical neck dissection with a pectoralis major pedicle flap was performed.
Axial CT shows an area of soft-tissue attenuation surrounding the right neurovascular
bundle. Note that the fat planes are obliterated.
13. Radiation Therapy
Radiation therapy for head and neck cancer is classified into two
types:
1.External beam radiation therapy which uses photon, electron
beam or proton beam radiation delivered from a source external
to the patient.
2.Brachytherapy which uses radioactive sources, such as iodine
seeds, iridium or cesium, that are implanted in the patient
permanently or temporarily.
14. Changes after radiation therapy are divided into :
1. Early reactions or complications are observed during the
course of RT or within 90 days after treatment.
2. Late complications, appear more than 90 days after the
completion of RT, may take months to years to emerge and are
often irreversible.
Concurrent chemo-radiation approaches, neoadjuvant
chemotherapy, and altered fractionation regimens have
improved treatment outcomes, although with increased early
toxic effects.
15. CT and MR imaging findings of early reactions to RT are
thickening of the skin and platysma, reticulation of the
subcutaneous fat, edema and fluid in the retropharyngeal
space, increased enhancement of the major salivary glands,
thickening and increased enhancement of the pharyngeal walls,
and thickening of the laryngeal structures .
16. SCC of the hypopharynx.
Axial contrast-enhanced CT 3 months after RT shows thickening of the skin and platysma,
reticulation of the subcutaneous fat, edema and fluid attenuation in the retropharyngeal
space, increased enhancement of the submandibular glands.
17. On the other hand, late reactions to radiation therapy include
atrophy of the salivary glands and thickening of the pharyngeal
constrictor muscle, platysma and skin.
18. SCC of the hypopharynx, 1 year after completion of RT.
Contrast-enhanced fat-saturated T1-weighted MR images show atrophy of the parotid
and submandibular glands and thickening of the pharyngeal constrictor muscle and
skin.
20. Tumor Recurrence
Tumors typically recur within the first 2 years after treatment.
The most common locations for tumor recurrence are in the
operative bed and at the margins of the surgical site.
CT demonstrates recurrence as an infiltrating slightly
hyperattenuating mass with enhancement, with or without bone
destruction.
Tumor recurrence has attenuation similar to that of muscle,
therefore, if a suspected mass has lower attenuation than that of
muscle, it is unlikely to be a malignancy and often is related to
edema.
21. Tumor recurrence in a 47-year-old man with SCC of the left maxillary sinus. A left
total maxillectomy and midface reconstruction with a flap had been performed.
An axial contrast-enhanced CT image shows a heterogeneously enhancing mass
adjacent to the flap.
22. MR imaging demonstrates tumor recurrence as an infiltrative
mass with intermediate T1-weighted signal intensity,
intermediate to high T2-weighted signal intensity and
enhancement.
23. The differential diagnosis for tumor recurrence includes a
vascularized scar, which represents early fibrosis.
Differentiation of a vascularized scar from tumor recurrence is
difficult because such a scar appears as a soft-tissue mass with ill-
defined margins and enhancement, which is similar to the findings
for tumor recurrence at both CT and MR imaging.
Retraction and decreased signal intensity on T2-weighted MR
images at the follow-up examination are suggestive of fibrosis.
In addition, diffusion-weighted MR imaging is a useful tool to
differentiate tumor recurrence from normal postoperative changes
and fibrosis.
High signal intensity on diffusion-weighted MR images with a
decreased value for the (ADC) is suspicious for recurrence.
24. Tumor recurrence in a
patient with SCC of the
oropharynx.
T1-weighted (a) DWI (b)
and ADC map (c)
obtained at 1 year 7
months after
chemoradiation therapy
show a mass in the right
tonsil.
The mass has low signal
intensity on the T1-
weighted image (a) and
high signal intensity on
the diffusion-weighted
image (b), with a reduced
value for the ADC (c).
25. Perineural tumor spread is a unique form of tumor recurrence.
Most commonly seen with SCC, followed by adenoid cystic
carcinoma, malignant lymphoma and malignant schwannoma.
The imaging findings of perineural tumor spread are nerve
enlargement with enhancement, foraminal enlargement, obliteration
of fat planes and replacement of the skull base foramina with soft
tissue.
However, granulation tissue and posttreatment scarring may also
result in obliteration of fat planes and apparent soft-tissue infiltration
into the skull base foramina.
Close correlation with prior images and clinical symptoms can help
distinguish perineural tumor spread from the effects of treatment.
Follow-up imaging may be required in equivocal cases.
26. A case of adenoid cystic
carcinoma of the left
sublingual gland.
Five years after surgery and
RT, she presented with left
cheek pain.
Coronal contrast-enhanced
fat-saturated T1-weighted
MR image shows a tubular
mass located along the
course of the left cranial
nerve V3 and involving the
cavernous sinus.
Note the enlargement of
the left foramen ovale and
the loss of the normal fat
pad.
28. Most complications related to surgery occur in the early period after
treatment.
1. A fluid collection is sometimes seen after surgery, and serous
retention often resolves spontaneously, requiring no further
treatment.
29. 2. Chylous fistula
Occurs in 1%–2% of patients after neck dissection, especially when
level IV nodes are dissected.
Chylous fistula is often located in the lower left portion of the neck,
so this characteristic location helps raise the suspicion of this
complication.
Early surgical complications such as serous retention, abscess,
hematoma and chylous fistula often show imaging findings similar to
those of a fluid collection with peripheral enhancement at CT and
MR imaging.
30. Fistula after tumor
resection, left-sided
radical neck dissection,
and tracheostomy in a 69-
year-old man with SCC of
the left side of the base of
the tongue.
At 10 days after surgery,
he presented with a fever.
Coronal contrast-
enhanced CT image shows
the formation of a
pharyngocutaneous fistula
in the left side of the neck.
31. 3. Flap necrosis is a rare complication.
Flap failure is associated with vascular thrombosis, the majority of
which is venous in origin, occurring within 3 days after surgery.
Therefore, the detection of thrombus in the artery and vein is
important in the evaluation of the viability of the flap.
SCC of the hypopharynx. A partial hypopharyngectomy, right-sided modified neck dissection, and
pharyngeal reconstruction with a free jejunal flap.
(a) Non enhanced CT image obtained 5 days after surgery shows slightly increased attenuation of the
jejunal free flap. (b) Contrast-enhanced CT image shows no enhancement in the flap. Note the occlusion
of the right internal jugular vein.
33. Mucosal Necrosis
Uncommon but important late toxic effect of RT, greatest during the
first 6–12 months after RT.
May cause pain and interferes with the patient’s ability to chew and
swallow.
In more than 95% of cases, soft-tissue necrosis heals spontaneously,
but healing may take 6 months or more.
At CT and MR imaging, mucosal necrosis shows a lack of mucosal
enhancement with or without ulceration. Pockets of gas adjacent to
the lesion should raise suspicion for tissue necrosis. Gas is better
identified by CT, compared with MRI.
Clinical correlation is essential for mucosal complications because it is
easier to be diagnosed clinically than by imaging.
34. SCC of the larynx. 5 months after RT, complained of severe odynophagia.
Contrast-enhanced CT shows the non enhancing area in the hypopharyngeal mucosa
and a small gas pocket adjacent to the lesion, findings that indicate tissue necrosis.
35. Osseous Complications
Osteoradionecrosis
in general, it is a condition in which irradiated bone becomes
devitalized and exposed through the overlying skin or mucosa,
persisting without healing for at least 3 months.
Occurs 1–3 years after radiation therapy.
Sites: skull base, temporal bone, mandible, maxilla and hyoid bone.
Of these, the mandible is the most commonly affected because of its
superficial location and relatively poor blood supply.
CT demonstrates a focal lytic area with cortical destruction, sequestra
formation and loss of the trabeculation pattern.
36. A 64-year-old man with SCC of the right tonsil. Coronal CT images show a focal lytic area with
cortical destruction and a pathologic fracture in the right mandibular ramus.
37. Osteoradionecrosis
MR images show abnormal signal intensity in the bone marrow, with
cortical destruction. Pathologic fracture, soft-tissue thickening, and
fistula formation are sometimes seen.
A 70-year-old man with SCC of the right tonsil. Surgery and RT.
Axial T1-weighted (a) and fat-saturated T2-weighted (b) MR images show a T1-hypointense and
heterogeneous slightly T2-hyperintense area in the right mandibular body.
38. Osteoradionecrosis
Although these imaging findings mimic those of tumor recurrence, the
presence of an associated soft-tissue mass favors a diagnosis of tumor
recurrence.
The identification of cortical defects remote from the primary tumor
site favors the diagnosis of osteoradionecrosis.
39. SCC of the left lower gingiva. Axial CT image shows a focal lytic area with
cortical destruction in the mandible.
Note the associated soft-tissue mass. The histopathologic findings from biopsy
helped confirm the tumor recurrence.
40. Vascular Complications
Accelerated atherosclerosis and thrombosis of the IJV or carotid
artery are well-known complications after RT.
Formation of a pseudoaneurysm of the internal carotid artery is
another rare complication.
It occurs most often in patients who have undergone high-dose
radiation therapy, with a latency period between 4 months and 20
years.
The imaging findings mimic those of other atherosclerotic disease
and cannot be differentiated from them.
Radiation-induced vasculopathy is often bilateral and related to the
irradiated field.
41. SCC of the larynx treated with RT.
Axial contrast-enhanced CT images obtained at 2 years (a) and 5 years (b) after radiation
therapy show the progression of bilateral thickening of the walls of the common carotid
arteries.
42. Radiation-induced Lung Disease
RT for patients with head and neck cancer often includes the apical
aspect of the thorax, to encompass the supraclavicular and level IV
nodal areas and results in bilateral apical radiation-induced lung
changes.
Clinical manifestations:
1- Acute radiation pneumonitis; occurs within 1–3 months after RT.
2-Late radiation lung fibrosis; occurs within 6–12 months after RT.
Imaging findings of radiation pneumonitis are focal ground-glass
attenuation or consolidation or both.
Radiation pneumonitis gradually resolves but progresses to radiation
lung fibrosis if the damage is severe.
Radiation lung fibrosis is shown to be a well-defined area of volume
loss, linear scarring and traction bronchiectasis
43. A 60-year-old woman with SCC of the tongue after surgery and RT.
(a)Radiation pneumonitis: CT obtained 3 months after RT shows multiple foci of ground-glass
attenuation and consolidation in the bilateral lung apices.
(b)Radiation fibrosis: CT obtained 6 months after RT shows an area of well-defined ground-
glass attenuation with volume loss and linear scarring.
44. Radiation-induced Brain Necrosis
Irradiation of the skull base for the treatment of patients with skull
base tumors or skull base invasion may cause damage to adjacent
brain tissue.
Radiation-induced focal brain necrosis often occurs within 2 years
after radiation therapy.
Focal brain necrosis is depicted as a ring-enhancing mass with variable
edema on CT and MR images.
45. A 54-year-old woman after radiation therapy for a chondrosarcoma of the left cavernous sinus
and skull base. Two years after RT, she complained of nausea and memory loss.
(a)Axial T2-weighted MR image shows the mass with surrounding edema in the left temporal
lobe.
(b)Coronal contrast-enhanced fat-saturated T1-weighted MR image shows irregular ring
enhancement of the mass.
46. Differentiation from metastasis, high-grade glioma or abscess is
difficult.
Diffusion-weighted MR imaging, MR spectroscopy, and PET/CT may
be used for differentiation.
With DW MR imaging, there is elevated values of the ADC in areas of
brain necrosis, compared with the values in intact normal brain
parenchyma and tumor.
MR spectroscopy demonstrates the metabolite changes, such as
reduced N-acetylaspartate and elevated lactate levels, in the necrotic
tissues.
At PET/CT, decreased metabolic activity in brain necrosis may be
seen.
47. Radiation-induced Neoplasm
Radiation-induced neoplasm is rare.
Various types including meningioma, sarcoma (osteosarcoma,
malignant fibrous histiocytoma), osteochondroma, schwannoma,
osteoblastoma, squamous cell carcinoma and lymphoma.
The diagnostic criteria of postirradiation osteosarcoma include a
lesion centered in irradiated bone without a primary malignant
osteoblastic lesion, arising after a latency period of at least 3 years
after the completion of RT.
Imaging findings mimic those of primary osteosarcoma.
48. A 45-year-old woman after RT for a SCC of the nasopharynx. 9 years after RT, she
presented with left mandibular pain and swelling.
Contrast-enhanced fat-saturated T1- weighted MR shows a heterogeneously
enhancing mass at the location of the left lateral pterygoid muscle, with destruction of
the left mandibular ramus.
49. Conclusions
In patients who have been treated for head and neck cancer,
the typical posttreatment changes are based on the various
types of therapy, including surgery with and without
reconstruction, neck dissection and radiation therapy.
Knowledge of the various treatment methods and their
expected and unexpected posttreatment imaging findings helps
to make an accurate diagnosis and avoid unnecessary further
diagnostic work-up.
