Download Scanning the Post Thyroidectomy Neck

Scanning the Post Thyroidectomy Neck
Teresa M Bieker, MBA, RDMS, RDCS, RVT
Lead Sonographer
University of Colorado Hospital
Appearance of Normal Cervical Lymph Nodes
Appearance of Abnormal Cervical Lymph Nodes
Identifying Zones/Levels of the Neck
Scanning Technique and Protocol
Thyroid cancer is the most common endocrine cancer
In 2011, there where 48,020 new cases (26,550 women, 11,470 men) and 1,740
deaths
For 2013, American Cancer Society estimates 60,220 new cases (46,970 women,
13,250 men) and 1,850 deaths
Two thirds of patients are between 20-55 with a mean age of 45
Causes include:
occupational risks
diet
lifestyle
parity
family history
Well Differentiated Thyroid Cancer:
Papillary
Follicular
Arise from thyroid follicular cells
Account for 80-90% of all thyroid cancers
Poorly Differentiated Thyroid Cancer:
Medullary (5-10%)
Anaplastic (1-2%)
Thyroid cancer is treatable; however, outcome is dependent
on stage (I-IV)
Five year survival rates:
Papillary: 51% to >99%
Follicular: 50% to >99%
Medullary: 28% to near 100%
Anaplastic: 7%
Age
Distant metastasis
Local invasiveness
Cervical lymph node metastasis
Tumor size
Multifocality
Tumor subtype
T = Tumor
N = Node
M = Distal Metastasis
TX: Primary tumor cannot be assessed
T0: No evidence of primary tumor.
T1: Tumor ≤2 cm in greatest dimension limited to the thyroid.
T1a: Tumor ≤1 cm, limited to the thyroid.
T1b: Tumor >1 cm but ≤2 cm in greatest dimension, limited to the thyroid.
T2: Tumor >2 cm but ≤4 cm in greatest dimension, limited to the thyroid.
T3: Tumor >4 cm in greatest dimension limited to the thyroid or any tumor with minimal
extrathyroid extension (e.g., extension to sternothyroid muscle or perithyroid soft
tissues).
T4a: Moderately advanced disease.
Tumor of any size extending beyond the thyroid capsule to invade subcutaneous soft
tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve.
T4b: Very advanced disease.
Tumor invades prevertebral fascia or encases carotid artery or mediastinal vessels
NX: Regional lymph nodes cannot be assessed.
N0: No regional lymph node metastasis.
N1: Regional lymph node metastasis.
N1a: Metastases to Level VI (pretracheal, paratracheal, and
prelaryngeal/Delphian lymph nodes).
N1b: Metastases to unilateral, bilateral, or contralateral cervical
(Levels I, II, III, IV, or V) or retropharyngeal or superior
mediastinal lymph nodes (Level VII)
M0: No Distant metastasis
M1: Distant metastasis
Stage
T
N
M
Younger then 45 years
I
any T
any N
MO
II
any T
any N
M1
45 years and older
I
T1
N0
M0
II
T2
N0
M0
III
T3
N0
M0
T1
N1a
M0
T2
N1a
M0
T3
N1a
M0
T4A
N0
M0
T4A
N1a
M0
T1
N1b
M0
T2
N1b
M0
T3
N1a
M0
IVA
For well differentiated thyroid cancer, there is a 9-30%
recurrence rate within the first decade after diagnosis
Most recurrences occur within the thyroid bed or cervical
lymph nodes
60-75% occur in Z3 or Z4
20% occur in Z6
Tend to affect the ipsilateral neck
Total or near total thyroidectomy is the standard treatment for
thyroid cancer. Z6 lymph nodes can also be removed at this
time
If the lateral/cervical lymph nodes are involved, a neck
dissection is also performed
Ultrasound and FNA are essential for surgical management
Physical palpation exam by endocrinologist/surgeon
Depending on extent of disease:
Iodine 131 whole body scan
Radioactive iodine ablation therapy
Chest x-ray
CT/MRI/PET
Neck ultrasound/Labwork (6-12 months)
Typically drawn every 6-12 months
Thyroglobulin (Tg)
Specific protein secreted from thyroid tissue
Tg levels should be undetectable in disease free patients
If Tg increases, it is likely caused by recurrent tumor
Tg Antibodies
Present in 20-25% of thyroid cancer patients
If antibodies are positive, Tg levels are falsely decreased
Tg antibodies typically decrease over several years
When disease in present, antibodies can increase
Thyroid Stimulating Hormone (TSH) - suppressed by medication
There are approximately 300 lymph nodes in the neck
Normal nodes have a cortex and medulla covered by a fibrous
capsule
Cortex: contains lymphocytes packed together forming
spherical lymphoid follicles
Medulla: contains trabeculae and medullary cords and sinuses.
Multiple medullary sinuses form the echogenic hilum
A main artery and vein enter/exit the node at the hilum
training.seer.cancer.gov
Common Locations
Normal Appearance
Abnormal Appearance
Arranged in chains
Commonly visualized along:
Jugular chain
Submandibular gland
Supraclavicular region
Thyroid bed
ATA recommends U/S pre and post thyroidectomy
More sensitive in detecting lymph nodes and determining benign vs
malignant
More cost effective
Quicker, non-invasive
No radiation
Can detect disease as small as 2-3mm (often before palpated or detected
by Tg)
FNA
Very operator dependent
12-15 MHz, 8MHz curved
Patient Position
Supine with neck extended
Elevating the head 20o in obese patients may help
Neck rotation
Image optimization
Indications:
Routine screening
Elevated TG
Follow-up
Correlation with NM, CT, PET
Zones 1-7 are evaluated and imaged
Residual thyroid tissue
Recurrent thyroid tumor
Abnormal lymph nodes
ZONES
LANDMARKS
IA
Midline. Anterior to the digastric muscle and superior to the hyoid bone Submental
IB
Lateral to zone IA, but medial or anterior to the submandibular gland
IIA
IIB
III
IV
NODAL GROUP
Submandibular nodes
Anterior or medial to the interior jugular vein but Lateral/posterior to the Upper internal jugular chain. More superiorly,
submandibular gland. Superior to the hyoid bone
the parotid nodes.
Upper internal jugular chain. More superiorly,
Posterior to the interior jugular vein
the parotid nodes.
From the level of the hyoid bone inferiorly to the cricoid arch. Lateral to
Middle internal jugular chain
the common carotid artery.
From the level of the cricoid arch inferiorly to the level of the clavicle.
Lower internal jugular chain
Lateral to the common carotid artery.
VA
Posterior to the sternocleidomastoid muscle, from the base of the skull to Supraclavicular fossa/posterior triangle (spina
the cricoid arch
accessory chain and transverse cervical chain
VB
Posterior to the sternocleidomastoid muscle from the croicoid arch to the Supraclavicular fossa/posterior triangle (spina
level of the clavicle
accessory chain and transverse cervical chain
VI
VII
Sup Clav
Anterior/medial to the common carotid arteries from the level of the
hyoid to the manubrium
Anterior/medial to the common carotid arteries, inferior to the sternal
notch
Lateral to the common carotid artery. At or inferior to the clavicle
Anterior cervical nodes, pre and paratracheal
Anterior, upper mediastinal nodes
Supraclavicular nodes
It is not unusual to see multiple normal nodes in the neck
The number of normal nodes visualized increases with age
Characterized by:
Location
Shape
Size
Echogenicity
Vascular pattern
Presence of echogenic hilum
Hypoechoic cortex
Echogenic hilum
Strong predictor of a normal node
Maybe difficult to visualize in small nodes
One feeder vessel (hilar flow)
Cylindrical or cigar shape
Lose elliptical shape and become more rounded
Malignant cells invade the node, disrupting the hilum
96% of malignant nodes lack a fatty hilum
Become hyperechoic with papillary invasion but hypoechoic with
medullary and lymphoma.
Increase in echogenicity due to the presence of Tg within the
lymph node
Microcalcifications
Mixed or peripherial flow
Cystic in advanced disease
Hilar: flow branches radially from the hilum
Peripheral: flow is present along the periphery of the node but
does not arise from the hilar vessels
Mixed: hilar and peripheral flow
Absence of flow despite optimal Doppler settings
Literature is inconsistent on benefit of color and pulsed Doppler
Following thyroidectomy, the paratracheal region should be
homogeneous
Z6 masses can include:
Postoperative scarring
Muscle
Necrosing fat
Suture granulomas
Parathyroid gland
Lymph node
Remnant tissue
Metastasis
Medial or anterior to the SMG
Midline/superior to hyoid bone
Nodal group:
submental/submandibular
Unusual to have papillary
involvement in Zone 1
Often see reactive nodes
Anterior/medial to the CCA
From the hyoid inferiorly to the
manubrium
Nodal group: anterior cervical
nodes, pre and para tracheal
20% of recurrences are in Zone
6
Lateral/posterior to the SMG
Superior to the hyoid bone (CCA
bifurcation)
Nodal group: upper IJ chain,
parotid nodes
Reactive nodes can be seen in
Zone 2
Uncommon for PTC, but can occur
From the level of the hyoid (CCA
bifurcation) to the cricoid
cartilage (level of expected
thyroid bed)
Lateral to CCA
Nodal group: middle IJ chain
60-75% of recurrences are in
Zone 3 or 4
From the cricoid arch to the level
of the clavicle (thyroid bed level)
Lateral to the CCA
Nodal group: lower IJ chain
60-75% of recurrences are in
Zone 3 or 4
Anterior/ medial to CCA
At or inferior to the sternal notch
Nodal group: anterior, upper
mediastinal nodes
Zone 7 vs Notch:
Zone 7 is inferior to the
subclavian
This changes surgical
management. “Notch” nodes
can be removed during
standard thyroidectomy. Zone
7 nodes requires a more
extensive surgery
Lateral to the CCA
At or inferior to the clavicle
Nodal group: supraclavicular
nodes
Posterior to sternocleidomastoid,
superior to clavicle
Nodal group: supraclavicular
fossa, posterior triangle
Uncommon location for PTC
recurrence
We do not label A or B for Zones 1, 2, 5
Evaluate Zone 5 only if palpable
Arrow normal nodes
If no nodes are seen, take image labeled “lateral neck”
Zone 2 is lateral to SMG only. It does not extend midline.
Measure largest or most worrisome node in each zone, can number others
Measure largest or most worrisome thyroid nodule
Take cine if unsure
If less then 5mm, nodes are difficult to track
Is the abnormality in Zone 6 reproduceable in all 3 planes? If
not, don’t measure
Can this be biopsied?
To determine Zone 3/4 vs Zone 6, put the patient in a neutral
position
Thyroid bed vs Zone 6 labeling: Use Z6 after thyroidectomy or
to measure abnormality superior or inferior to the thyroid
Echogenic fatty hilum
No echogenic hilum
Cylindrical in shape
Round
Hilar flow
Mixed or peripheral flow
Echogenic (PTC)
Microcalcifications
Cystic in advanced disease
Additional Reference:
Bieker T. Scanning the Post-Thyroidectomy Neck:
Appearance and Technique.
Journal of Diagnostic Medical Sonography.
2010. 26(5): 215-223.