18F-FDG PET/CT Findings of Perineural Involvement in Head...
Transcript of 18F-FDG PET/CT Findings of Perineural Involvement in Head...
Perineural invasion (PNI) is the process of neoplastic
invasion of nerves and is an under-recognized route of
metastatic spread. It is emerging as an important
pathologic feature of many malignancies, particularly in
head and neck cancers, associated with decreased
survival, increased and earlier recurrence. PNI status
often significantly affects surgical strategies and
adjuvant treatments in head and neck cancers. MRI has
been the gold standard imaging modality for the
evaluation of PNI. FDG PET/CT has been increasingly
used for staging and restaging head and neck cancers.
Beyond locoregional disease and lymph node metabolic
characterization, different PET imaging patterns
suggesting PNI can also be identified. Our goal is to
demonstrate different examples of PNI visualized by
PET/CT and the correlation with other cross sectional
imaging modalities, such as CT and MRI.
• PNI is a poor prognostic indicator in head neck
malignancies.
• Asymmetric FDG uptake in the head and neck should
be always evaluated in all 3 planes and MIP on PET-
only images.
• FDG PET/CT patterns can suggest PNI and could be
described as such.
• Increased awareness of such patterns can be helpful in
the evaluation and cross sectional correlation of cases
suggestive of PNI.
• Review of the MIP of the head and neck
• Review of PET-only images in the axial, coronal and sagittal
plane. Asymmetries are noted.
• Foci of asymmetric FDG uptake get also identified in the other
planes and their pattern is recognized (focal, linear etc.)
• Findings are correlated with CT portion of PET/CT and other
available modalities
Introduction - Aim
Proposed Algorithm
Key points
References
Case 2: Hypoglossal n.
Case: 54 yo male with history of
squamous cell carcinoma of the right
tongue base, status post definitive
chemoradiation more than 1 year
before. PET/CT for evaluating
recurrence showed a large focus of
FDG uptake in the right tongue base,
suspicious for tumor recurrence, as well
as a linear focus of uptake extending
from the base of the tongue to the base
of the skull, concerning for perineural
spread along the hypoglossal n.
Perineural involvement was confirmed
with subsequent biopsy.
MIP, sagittal view Source: Wikipedia
Source: Radiology Anatomy Atlas Viewer
Case 4: Trigeminal Ganglion
Case: 76 y/o female with history of
SCCA of the right lower lip, extending
into mental nerve and foramen ovale,
status post surgical resection and
combined chemoradiation, referred for
restaging 4 months afterwards.
PET/CT shows linear extension of
FDG activity through the trigeminal
nerve, foramen ovale and petrous apex
to the mesencephalus (trigeminal
ganglion).
MRI: Perineural spread in the same
location, progression of disease.
Case: 49 yo male with radiation-induced malignant
histiocytoma of the right jaw and skull base, status post
right hemimandibulectomy, and remote history of
squamous cell carcinoma of the tongue 13 years before,
treated with primary external beam radiation without
chemotherapy.
PET/CT study performed for restaging shows an FDG-avid
right masticator space mass involving the mandible, as
well as a linear focus of uptake in the ramus of the
remaining right mandible, suspicious for perineural spread.
MRI was in accordance and also suggestive for perineural
spread through the foramen ovale and rotundum. These
findings were subsequently confirmed by biopsies twice.
Case 1: Inferior Alveolar n.
Case: 54 y/o male
with recent diagnosis
of large B-cell
lymphoma of the
mandible, stage IB.
PET/CT shows a focus
of increased uptake in
the ramus of the right
mandible along the
course of the right
inferior alveolar nerve,
highly suspicious for
lymphomatous
involvement.
CECT of the head
confirmed these
findings showing the
nerve foramina
expansion and bony
erosion.
Case 5: Mandibular n. Case 6: Mental n.
Case 3: Maxillary n.
Case: 79 yo female with biopsy proven meningioma of the skull base and
infratemporal fossa. She underwent PET/CT for staging, which showed a linear
focus of moderate uptake (SUVmax =3.67)
Corresponding to a soft tissue mass along the right foramen ovale and 2nd and 3rd
branch of the trigeminal n. MRI showed gross involvement of the right V3 foramen
ovale with no significant enlargement of the foramen, but a large amorphous
component of the mass is seen contiguous in the right infratemporal fossa.
Case 7: Inferior Alveolar n.
Source: Wikipedia
Source: Wikipedia
1. Gandhi, D., S. Gujar, et al. (2004). "Magnetic resonance imaging of
perineural spread of head and neck malignancies." Top Magn Reson
Imaging 15(2): 79-85.
2. Caldemeyer, K. S., V. P. Mathews, et al. (1998). "Imaging features and
clinical significance of perineural spread or extension of head and neck
tumors." Radiographics 18(1): 97-110; quiz 147.
3. Radiology Anatomy Atlas Viewer
(http://web.mac.com/rlivingston/RAAViewer/)
4. Wikipedia (www.wikipedia.org)
Materials and Methods
We identified cases of head and neck cancer patients
from our institution with suspected or established
perineural involvement. All patients underwent a whole
body PET/CT study and afterwards a separate head and
neck component, 90 mins after IV injection of 481 – 555
MBq (13-15 mCi) of 18F-FDG, in a Philips Gemini TF-
16 Time of Flight PET/CT scanner. Oral or IV contrast
was not used and low-dose CT was acquired for
attenuation correction and anatomical localization only.
Our algorithm for interpreting the head and neck part of
the PET/CT studies included careful review of PET only
images in all three planes and in maximum intensity
projection (MIP), and correlation with CT images.
Source: Radiology Anatomy Atlas Viewer
MIP, coronal and sagittal view
Case: 76 yo female with history of
SCCA of the right lower lip, with
involvement of the mental nerve
and intracranial progression (same
patient as case 4). PET/CT shows
the extension along the mandibular
nerve. MRI: Same findings.
Case: Again, the 76 y/o female with
history of SCCA of the right lower lip and
perineural extension along the mandibular
ramus of the trigeminal nerve. PET/CT
shows the initial extension to the mental
ramus of the mandibular nerve in the site
of the primary tumor in the right lower lip.
MRI: Focal area of low signal in the right
lip, suspicious for mental nerve
involvement.
Source: Radiology Anatomy Atlas Viewer
Source: Radiology Anatomy Atlas Viewer
Source: Radiology Anatomy Atlas Viewer
Source: Radiology Anatomy Atlas Viewer
Source: Wikipedia
Source: Wikipedia
18F-FDG PET/CT Findings of Perineural Involvement in Head and Neck
Malignancies Fabio Paes MD, Dimitrios Kalkanis MD, Osama Gomaa MD and Aldo Serafini MD
Department of Radiology, Division of Nuclear Medicine, University of Miami, Miami, Florida
Contact email: [email protected]