1 - Imaging anatomy of the oral cavity
The oral cavity is the most ventral portion of the aerodigestive tract.
It is subdivided into:
- Lips
- Floor of the mouth
- Oral tongue (anterior two-thirds)
- Gingival and buccal mucosa (includes labial and jugal mucosas)
- Hard palate
- Retromolar trigone
Boundaries:
- Superiorly: nasal cavities
- Inferiorly: mylohyoid muscle (separates floor of mouth from submandibular space)
- Laterally: lips,
buccomasseteric region,
retromolar trigone
- Posteriorly: oropharynx
1.1 - Imaging anatomy: Computed tomography (CT)
Fig. 1: Contrast-enhanced computed tomography (CECT) images, axial plane. 1: Hard palate. 2: Hard palate mucosa. 3: Uvula/soft palate. 4: Anterior tonsillar pillar/soft palate. 5: Parapharyngeal space. 6: Medial pterygoid muscle. 7: Masseter muscle. 8: Parotid gland. 9: Retromandibular vessels. 10: Alveolar process of the maxilla. 11: Ascending ramus of the mandible.
References: Department of Radiology, University of Sao Paulo
Fig. 2: CECT images, axial plane. 1: Oral tongue. 2: Base of the tongue (part of the oropharynx). 3: Soft palate. 4: Retromolar trigone. 5: Glossotonsillar sulcus. 6: Anterior tonsillar pillar. 7: Buccinator muscle and buccal space. 8: Medial pterygoid muscle. 9: Ascending mandibular ramus.
References: Department of Radiology, University of Sao Paulo
Fig. 3: CECT images, axial plane showing the floor of the mouth. 1: Sublingual gland. 2: Lingual vessels. 3: Geniohyoid muscle. 4: Lingual septum. 5: Lingual tonsils. 6: Vallecula. 7: Submandibular gland. 8: Alveolar process of the mandible. 9: Inferior alveolar nerve canal.
References: Department of Radiology, University of Sao Paulo
Fig. 4: CECT images, sagittal plane. The oral cavity (OC) is anterior to the circumvallate, part of the oropharynx (OP). The OP is located between the rhinopharynx (RP - above the hard palate) and the hypopharynx (HP - below the vallecula). 1: Hard palate. 2: Soft palate. 3: Oral tongue. 4: Geniohyoid muscle. 5: Hyoid bone. 6: Epiglottis.
References: Department of Radiology, University of Sao Paulo
Fig. 5: CECT images, coronal plane. 1: Hard palate. 2: Hard palate mucosa. 3: Oral tongue. 4: Floor of mouth. 5: Lingual vessels. 6: Sublingual gland. 7: Mylohyoid muscle. 8: Anterior belly of the digastric muscle.
References: Department of Radiology, University of Sao Paulo
Fig. 6: CECT images, coronal plane. 1: Rhinopharynx. 2: Soft palate. 3: Oral tongue. 4: Lingual septum. 5: Mylohyoid muscle. 6: Anterior belly of the digastric muscle. 7: Uvula/soft palate. 8: Lingual tonsil. 9: Submandibular gland.
References: Department of Radiology, University of Sao Paulo
1.2 - Imaging anatomy: Magnetic resonance (MR)
Fig. 7: Axial T1-weighted magnetic resonance imaging (MRI) at the level of the oral tongue. TIM: Intrinsic muscles of the tongue. LS: Lingual septum. MB: Mandibular body. SP: Soft palate. MPM: Medial pterygoid muscle. PPS: Parapharyngeal space.
References: Garcia M et al. Postsurgical Imaging of the Oral Cavity and Oropharynx: What Radiologists Need to Know. RadioGraphics 2015.
Fig. 8: Axial T1-weighted MRI at the level of the floor of mouth. MB: Mandibular body. GHM: Geniohyoid muscle. SLG: Sublingual gland. MHM: Mylohyoid muscle. HGM: Hyoglossus muscle. DMPB: Digastric muscle, posterior belly. LT: Lingual tonsils.
References: Garcia M et al. Postsurgical Imaging of the Oral Cavity and Oropharynx: What Radiologists Need to Know. RadioGraphics 2015.
Fig. 9: Axial T1-weighted MRI showing the submandibular space. SMG: Submandibular glands. DMAB: Digastric muscle, anterior belly. HB: Hyoid bone. PCM: Pharyngeal constrictor muscle.
References: Garcia M et al. Postsurgical Imaging of the Oral Cavity and Oropharynx: What Radiologists Need to Know. RadioGraphics 2015.
Fig. 10: Sagittal T1-weighted MRI emphasizing the tongue and its relationships. HP: Hard palate. SP: Soft palate. TIM: Tongue intrinsic muscles. GGM: Genioglossus muscle. GHM: Geniohyoid muscle. LT: Lingual tonsils. HB: Hyoid bone. Men: Mentum. Epi: Epiglottis.
References: Garcia M et al. Postsurgical Imaging of the Oral Cavity and Oropharynx: What Radiologists Need to Know. RadioGraphics 2015.
Fig. 11: Coronal T1-weighted MRI depicting the floor of the mouth. LS: Lingual septum. SLG: Sublingual gland. MB: Mandibular body. GGM: Genioglossus muscle. GHM: Geniohyoid muscle. DMAB: Digastric muscle, anterior belly. MPM: Medial pterygoid muscle.
References: Garcia M et al. Postsurgical Imaging of the Oral Cavity and Oropharynx: What Radiologists Need to Know. RadioGraphics 2015.
Fig. 12: Coronal T1-weighted MRI showing the oral tongue. HP: Hard palate. TIM:Tongue intrinsic muscles. LS: Lingual septum. MHM: Mylohyoid muscle. HB: Hyoid bone.
References: Garcia M et al. Postsurgical Imaging of the Oral Cavity and Oropharynx: What Radiologists Need to Know. RadioGraphics 2015.
2 - Imaging methods
- No imaging method is suitable to all occasions.
- The combination of modalities frequently improves radiologic evaluation.
- Advantages and disadvantages of each method must be considered when studying the oral cavity.
2.1 - Imaging methods: Radiography
- Panoramic radiographs are useful to detect bone invasion in advanced disease.
- Also used to evaluate the state of dentition and to plan dental extraction if high dose radiotherapy is needed.
- Advantages: Accessible and inexpensive.
- Disadvantages: Not suitable to perform local staging other than bone invasion.
Low sensitivity to detect small lesions.
Fig. 13: A and B (Patient 1): Visual inspection shows an ulcerated lesion on the alveolar ridge mucosa of the mandible on the right (A). Radiography (B) depicts extensive bone erosion of the body, angle and ramus of the mandible. C and D (Patient 2): Visual inspection shows a large ulcerated and vegetative lesion on the oral mucosa (C). The panoramic radiography (D) shows bone erosion.
References: Department of Radiology, University of Sao Paulo
2.2 - Imaging methods: Ultrasound
- Very useful as a screening method to detect nodal cervical metastasis.
- Also used to guide fine needle aspiration.
- Advantages: Accessible,
inexpensive,
radiation-free.
Doppler and elastography imaging may be used in addition to conventional evaluation.
- Disadvantages: Does not evaluate the primary oral cavity lesion (except for intraoral ultrasound,
used less frequently). Low specificity to differentiate inflammatory from neoplastic nodal compromise.
Fig. 14: A: Metastatic nodes are often enlarged and heterogeneous, with loss of the normal architecture and central fatty hilla. B: Doppler ultrasound detects peripheral and tortuous vessels suggesting neoangiogenesis. C: Cystic nodes are an important clue to HPV infection-associated oral malignancy.
References: Department of Radiology, University of Sao Paulo
2.2.1 - Imaging methods: Ultrasound in jugal tumours
- Ultrasound can be used as an adjunct to other imaging modalities.
- Examination is performed at rest,
positioning the transducer on the skin,
after the patient fills the mouth with water.
- Water distension of the oral vestible allows identification of anatomic layers in the cheeks,
depth of tumoral invasion and the relation of the lesion with adjacent structures.
Fig. 15: A: Normal ultrasound of the cheek with water distension. Red arrow (hypoecogenic layer): buccinator muscle. Asterisk (hyperecogenic layer): submucosa. Yellow arrow (slender hypoecogenic layer): mucosa. B: No lesion is identified in the left cheek with the conventional technique. C: After water distension, a small hypoecogenic lesion is seen in the mucosa and submucosa (arrow), blurring the buccinator muscle interface (arrowhead), not invading the adjacent subcutaneous fat.
References: Department of Radiology, University of Sao Paulo
Fig. 16: A: Conventional ultrasound technique, panoramic view depicting a large lesion in the face. There is invasion of the skin and subcutaneous fat (arrow). B: Conventional ultrasound technique, axial plane. Deep invasion is difficult to assess, once anatomic planes are not individualised. C: Ultrasound after oral cavity distension with water demonstrates lesion invasion of the mucosa, submucosa and buccinator muscle (full extension of the cheek).
References: Department of Radiology, University of Sao Paulo
2.3 - Imaging methods: Computed tomography
- Most common radiologic modality used to assess oral cavity cancer.
- Good temporal and spatial resolution.
- Advantages: Relatively accessible in most centers.
Multiplanar reformat better depicts lesions and their anatomic relations.
Method of choice to detect bone involvement.
Dynamic maneuvers are possible due to fast acquisition time in multidetector row CT.
- Disadvantages: Beam-hardening artefacts due to dental amalgam may degrade images.
Relatively low soft tissue contrast.
Exposure to radiation.
Fig. 17: A: Post-contrast computed tomography, axial plane demonstrates large, ulcerated lesion in the anterolateral aspect of the oral tongue (arrowheads). B: A large oral cavity and oropharynx lesion determines bone erosion (arrow). CT is the method of choice to demonstrate bone involvement.
References: Department of Radiology, University of Sao Paulo
2.3.1 - Imaging methods: Dynamic Maneuvers in CT
2.3.1.1: "Puffed-cheeks” maneuver
- Jugal,
gingival and lingual mucosae are usually coapted at rest.
- Distention of the oral mucosa lumen with air improves detection and correct staging of small lesions of the lips and oral mucosa.
- Patient blows uniformly through pursed lips.
Fig. 18: Mucosal lesions sometimes can be better seen during the "puffed cheeks" maneuver.
References: Department of Radiology, University of Sao Paulo
2.3.1.2: Open mouth maneuver
- Patients commonly have dental amalgams which produce beam-hardening artefacts that degrade images.
- This maneuver is indicated to improve detection and correct staging of small lesions in the oral cavity whenever artefacts are present.
- A device (e.g.,
a syringe) is placed between teeth to ensure proper immobilization.
Fig. 19: Beam-hardening artefacts can obscure oral cavity lesions. The open mouth maneuver can be used to reduce its interference.
References: Department of Radiology, University of Sao Paulo
2.3.1.3: Tongue protrusion maneuver
- Small oral tongue lesions are difficult to appreciate due to apposition of soft tissues at rest and artefacts generated by dental amalgams.
- This maneuver improves detection and correct staging of small lesions in the oral tongue,
particularly in the lateral border and apex.
- Image is acquired while the patient protrudes the tongue.
Fig. 20: A and B: A suspicious area could be better interpreted as a lesion after the patient protrudes the tongue. C and D: Tongue protrusion can also be used to avoid beam-hardening artefacts.
References: Department of Radiology, University of Sao Paulo
2.4 - Imaging methods: Magnetic resonance
- Exceptional soft tissue detail.
- Generally preferred to assess the skull base,
pharynx and oral cavity.
- Advantages: Improved local staging and sensitivity to detect small lesions.
Study of choice to detect perineural spread.
Versatile: include different sequences such as diffusion-weighted MRI,
MR angiography,
perfusion/permeability,
etc.
Radiation-free.
- Disadvantages: Sensible to motion artefacts,
MRI contraindications (cardiac pacemaker,
claustrophobia,
etc).
Expensive,
not accessible in all areas.
Fig. 21: Infiltrative lesion in the lateral left border of the oral tongue with hyperintense signal in T2-weighted images (A), post-gadolinium enhancement (B) and restricted diffusion (C), confirmed on the ADC map (D). Restricted diffusion tends to occur in hypercellular lesions with dense nucleo-cytoplasmic ratio.
References: Department of Radiology, University of Sao Paulo
2.5 - Imaging methods: Positron emission tomography–computed tomography (PET-CT)
- 18F-fluorodeoxyglucose (FDG) PET.
- Uptake of FDG in metabolic active areas.
- Advantages: Increased sensitivity and specificity to detect nodal metastasis.
Assess clinically occult cancer.
Guide biopsy to most metabolic active area.
Newer tracers will potentially give additional molecular and receptor information.
- Disadvantages: False negatives-low metabolic tumours (salivary gland tumours),
necrotic lesions.
False positives-physiologic uptake (lymphoid tissue,
salivary glands).
Fig. 22: A: Increased FDG uptake in a large oral tongue lesion. B: A small lesion on the right lateral border of the tongue (arrow) with extensive bilateral nodal metastasis (arrowheads). C and D: Physiologic uptake of FDG in the lingual tonsil (arrow in C and D), sublingual (arrowheads) and submandibular glands (asterisks).
References: Department of Radiology, University of Sao Paulo
2.6 - Imaging methods: Positron emission tomography–magnetic resonance (PET-MR)
- Novel hybrid method that simultaneously acquires MR and FDG-PET images,
eliminating the need to register images
- Advantages: Combines excellent anatomic resolution,
angiographic and diffusion information provided by MRI with molecular and functional PET data.
Simultaneous anatomic and functional acquisition reduces registration error.
- Disadvantages: Expensive.
Restricted to few tertiary centers.
Recent method,
still under investigation.
Fig. 23: PET-RM images showing (A) necrotic lymphadenopathy in the left IIA level (arrow) with extensive FDG uptake (B) in the fused image.
References: Department of Radiology, University of Sao Paulo
3 - Oral cavity cancer and anatomic subsites
- The most common oral cavity cancer (90%) is squamous cell carcinoma (SCC).
- General imaging aspect: infiltrative soft tissue mass with moderate contrast enhancement.
- Routes of extension: submucosa,
direct invasion into adjacent structures,
perineural spread and lymph node metastasis.
- Each subsite has their own inherent peculiarities.
3.1 - Anatomic subsites: lips
- The lips are the most common site for SCC in the oral cavity.
- 90-95% occur in the inferior lip.
- As a superficial lesion,
clinical exam is sufficient to detect local extension in most cases.
- In small lesions,
careful inspection may detect subtle bony erosions along the alveolar process.
- In more advanced cases,
the tumour may invade the mandible and spread through the mental nerve.
Fig. 24: A and B (Patient 1): Superficial lesion on the lower lip without bone invasion. C and D (Patient 2): Advanced disease with extension to the floor of mouth and oral tongue, as well as large level IB lymphadenopathy (arrowhead).
References: Department of Radiology, University of Sao Paulo
3.2 - Anatomic subsites: floor of mouth
- Second most common oral cavity site for SCC.
- Generally tumours are more common in the anterior portion of the floor of mouth.
- In general,
anatomic structures are better seen on the coronal plane.
- Obstruction of the Warthon’s duct may lead to submandibular syaloadenitis.
- Invasion of the mylohyoid muscle: possible extension to the submandibular space.
- Denervation atrophy of the intrinsic muscles of the tongue may indicate hypoglossal nerve invasion.
Fig. 25: A and B (Patient 1): Lesion in the floor of the mouth and oral tongue with invasion of the mylohyoid muscle (arrows), better seen in the MRI (B), suggesting possible submandibular space extension. Also note metastatic level IB lymphadenopathy (asterisk in B).C (Patient 2): This small floor of mouth lesion (arrow) obstructs both main submandibular ducts (arrowhead). D (Patient 3): A large floor of mouth and gingival mucosa lesion (arrow) with bone erosion and dilation of the contralateral submandibular duct (arrowhead).
References: Department of Radiology, University of Sao Paulo
3.3 - Anatomic subsites: oral tongue
- Generally occur in the ventrolateral surface.
- Commonly extends beyond gross tumour margin seen on surgery,
particularly because of deep invasion (floor of the mouth,
oropharyngeal structures).
- Tumour thickness: should be measured preferably on the T1 post-gadolinium sequence.
Included in the new AJCC TNM classification and is an independent prognostic factor for recurrence and survival.
- Contralateral spread across the midline,
particularly if the lingual septum is involved,
should be carefully assessed.
- Relation with neurovascular bundle is important for surgical planning.
Fig. 26: A (Patient 1): Axial MRI of a lesion in the anterior tongue with contralateral spread and proximity with the lingual vessels (arrowheads). B (Patient 2): Axial MRI of a large lesion in the oral tongue with extension to the retromolar trigone (arrow) and oropharynx (arrowhead). C and D (Patient 3): Coronal CT of a discrete lesion in the tongue, better appreciated with the open mouth maneuver (D).
References: Department of Radiology, University of Sao Paulo
3.4 - Anatomic subsites: retromolar trigone
- Indolent growth and late clinical presentation.
- Important source of multidirectional tumour spread.
- Surgical resection is often difficult.
- Spread is clinically difficult to evaluate - imaging has a central role in staging.
- Potential spread into the masticatory space,
buccal space,
oral tongue,
floor of mouth,
oropharynx and superior constrictor muscles should not be missed.
- Look carefully for erosions in the ascending ramus of the mandible.
Fig. 27: A (Patient 1): Axial CT of a lesion in the right retromolar trigone (RMT) with extension to the oral tongue (long arrow), buccinator muscle (arrowhead), glossotonsillar sulcus and medial pterygoid muscle (short arrows). B and C (Patient 2): Axial CT of a lesion in the left RMT (arrow) with extension to the soft palate (asterisk). Also note discrete bone erosion in the left mandibular ramus (arrowhead).
References: Department of Radiology, University of Sao Paulo
3.5 - Anatomic subsites: alveolar ridge/gingival mucosa
- SCC that originates in the mucosa that covers the superior and inferior alveolar processes.
- Smaller lesions can be better appreciated with the puffed cheeks maneuver.
- Bone invasion: since there is proximity with the alveolar process,
lesions may determine bone erosion earlier.
- Radiologists must look for perineural spread along the inferior alveolar nerve and palatine canals
- Invasion of the maxillary sinus if the lesion originates in the upper alveolar ridge.
Fig. 28: A and B (Patient 1): Axial CT of a lesion in the jugal and gingival mucosa/alveolar ridge of the mandible (arrow) associated with extensive bone invasion (arrowheads). C and D (Patient 2): Axial CT of a lesion which invades the floor of mouth, inferior lip (arrow) and determines bone erosion (arrowhead in D).
References: Department of Radiology, University of Sao Paulo
3.6 - Anatomic subsites: hard palate
- SCC rarely arise from the hard palate.
Generally these lesions occurs associated with adjacent gingival tumours.
- More common hard palate lesions are minor salivary gland tumours (generally on the posterior aspect of the hard palate).
- Invasion of the overlying bone,
nasal cavity and maxillary sinus may occur
- Perineural spread along the greater and lesser palatine canals,
pterygopalatine fossa and even to the cavernous sinus (particularly if the histologic type is adenoid cystic carcinoma) must be identified
Fig. 29: A and B (Patient 1): Coronal CT of an enhancing lesion in the hard palate and right alveolar process of the maxilla (arrow) associated with bone erosion (arrowhead). C and D (Patient 2): Coronal CT of a larger, exophytic lesion which determines erosion of the right nasal cavity floor (arrow in C) and bone erosion of the alveolar process of the maxilla (arrowhead in D).
References: Department of Radiology, University of Sao Paulo
4 - Role of imaging in staging
4.1 - Local staging
- The new 8th edition of the AJCC TNM classification revised the primary tumour (T) category in oral cavity cancer.
- Deeply invasive tumours are more aggressive than superficial or exophytic lesions.
To reflect this,
depth of invasion (DOI) was incorporated into the new classification.
- DOI x tumour thickness: a pathological concept
- DOI: Measured from the basement membrane to tumour invasion (requires biopsy)
- Tumour thickness: Measured from the surface of the lesion to tumour invasion → Imaging methods can only measure tumour thickness (may be used as an imaging surrogate to the DOI).
Table 1: Local staging criteria for oral cavity cancer.
References: Department of Radiology, University of Sao Paulo
Fig. 30: Scheme showing the differences between superficial diameter, tumour thickness (TT) and depth of invasion (DOI, which can only be assessed with pathology). Superficial diameter is measured by visual inspection, but it frequently does not represent the true extension of the tumour invasion. Tumour thickness may be measured by imaging methods as a surrogate for the DOI, however exophitic or ulcerated tumours do not have coincident TT and DOI.
References: Department of Radiology, University of Sao Paulo
Fig. 31: This lesion would be previously classified as T2 (tumoral size between 2 and 4 cm) (A). However, tumour thickness measured in the coronal plane (20,0 mm) (B) upstages this disease to T3 according to the new criteria.
References: Department of Radiology, University of Sao Paulo
Fig. 32: Another example of a lesion which would be classified as T1 (tumoral size ≤ 2 cm) (C) but is upstaged to T3 due to tumour thickness of 10 mm (D).
References: Department of Radiology, University of Sao Paulo
4.2 - Bone involvement
- Imaging is pivotal since bone involvement is clinically difficult to evaluate.
- Must be actively searched: if present,
upstages disease to T4.
- Bone involvement manifests as erosive and/or infiltrative patterns.
- CT: Most sensitive method to detect erosions.
Cortical erosion,
aggressive periosteal reaction,
pathological fractures,
bone marrow sclerosis (may represent tumoral infiltration).
- MRI: Excellent to detect bone marrow infiltration (hypointense T1,
hyperintense T2,
post-gadolinium enhancement),
but unspecific: same aspect can be seen in inflammatory reaction,
periodontal disease,
osteoradionecrosis.
Fig. 33: A (Patient 1): Curved reformatted CT, bone window depicts a lesion with extensive cortical erosion (arrow). Also note bone marrow sclerosis and involvement of the inferior alveolar nerve canal (arrowheads) and the mental foramen (asterisk). Reformatted images are useful to see the relationship of the lesion with adjacent structures. B (T1) and C (T2) (Patient 2): MRI showing a subtle lesion with cortical interruption (arrowhead) and bone marrow infiltration (asterisk).
References: Department of Radiology, University of Sao Paulo
4.3 - Perineural spread
- Imaging is again crucial since perineural spread is frequently unsuspected clinically.
- Upstages disease to T4.
- If not detected may lead to ineffective treatment with unnecessary morbidity without changing the survival rate.
- Imaging findings: Foraminal enlargement; replacement of normal fat within the neural foramen; nerve thickening and post-gadolinium enhancement.
- Lesions may be not contiguous - complete nerve pathway must be evaluated!
Fig. 34: Patient with adenoid cystic carcinoma of the palate. MR images, T1 post-contrast. Lesion in the right palate (long arrow in A) with extension to the right pterygopalatine fossa (short arrows in B and C) along the course of the palatine nerves (arrowheads in C and D). Through the pterygopalatine fossa, the lesion disseminates along the foramen rotundum (dashed arrow in D).
References: Department of Radiology, University of Sao Paulo
4.4 - Nodal metastasis
- Lymph node status has important prognostic value in head and neck cancer.
- Classic criteria that influence staging: number,
size (largest diameter) and laterality of metastatic lymphadenopathy.
- The 8th edition of the AJCC TNM classification added extranodal extension (ENE) to the criteria.
- Radiological signs of ENE: Irregular borders,
perinodal fat stranding,
invasion of adjacent structures.
- If present,
ENE upstages disease to N3.
- Imaging may lack sensitivity to detect ENE in smaller nodes.
- Radiologic criteria must be used in addition to the physical examination to assign ENE.
Table 2: Nodal metastasis criteria for oral cavity cancer, p16-HPV negative.
References: Department of Radiology, University of Sao Paulo
Fig. 35: A and B: Axial CT shows lymphadenopathy with a hypoattenuating center (necrosis/liquefaction) (asterisks), which suggests metastatic spread regardless of nodal size. Also note radiological signs of extranodal extension (ENE) such as indistinct margins with adjacent structures (arrows) and stranding of the fat planes (arrowheads). C and D: PET-CT images show high FDG uptake in a right level IIA node (C) and in the periphery of a large right necrotic conglomerate (asterisk in D), as well as in other lymph nodes (arrowheads in D). Although reactive lymph nodes may show FDG uptake, it is usually lower compared with neoplastic lymphadenopathy, since in general neoplasias have increased glycolytic metabolism. E and F: Metastatic lymph nodes tend to have restricted diffusion on MRI (E), confirmed on the ADC map (F), owing to their increased cellularity, particularly when ADC values are low.
References: Department of Radiology, University of Sao Paulo
4.5 - Distant metastasis
- Knowledge of the presence of distant metastasis is crucial to plan further treatment.
- Most common targets: lung,
bone and liver.
- Imaging plays a key role in detecting distant metastasis,
since many are clinically silent.
- Whole-body diffusion MRI,
PET-CT and PET-MRI are very useful since they study multiple anatomic sites concomitantly.
Fig. 36: A: PET-MRI whole-body diffusion imaging. There is restricted diffusion in a left IB lymph node, favouring metastatic spread. Other sites did not demonstrate suspicious lesions. B: PET-CT shows FDG uptake in a large right cervical nodal conglomerate, in a small left cervical lymph node and two metastatic nodules on the inferior lobe of the left lung. C: CT depicts metastatic lesion on the left clavicle associated with a soft tissue mass. CT may be used to study specific anatomic sites or when PET-CT and whole-body diffusion are not available.
References: Department of Radiology, University of Sao Paulo