Scanning the Post Thyroidectomy Neck Teresa M Bieker, MBA, RDMS, RDCS, RVT Lead Sonographer University of Colorado Hospital

Objectives: Appearance of Normal Cervical Lymph Nodes Appearance of Abnormal Cervical Lymph Nodes Identifying Zones/Levels of the Neck Scanning Technique and Protocol

Background: 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

Types of Thyroid Cancer: 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%)

Outcomes: 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%

Factors Affecting Treatment/Outcomes: Age Distant metastasis Local invasiveness Cervical lymph node metastasis Tumor size Multifocality Tumor subtype

TNM Classification: T = Tumor N = Node M = Distal Metastasis

TNM Classification 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

TNM Classification: 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)

TNM Classification: M0: No Distant metastasis M1: Distant metastasis

TNM Staging: Stage T N M Younger then 45 years I any T any N MO II M1 45 years and older T1 N0 M0 T2 III T3 N1a IVA T4A N1b

Recurrence Rates: 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

Surgery: 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

Post Operative Evaluation: 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)

Labwork: 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

Lymph Nodes: 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

Cervical Lymph Nodes: jnccn.org

Lymph Node Anatomy: training.seer.cancer.gov

Lymph Nodes: Common Locations Normal Appearance Abnormal Appearance

Common Lymph Node Locations: Arranged in chains Commonly visualized along: Jugular chain Submandibular gland Supraclavicular region Thyroid bed

Why Ultrasound? 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

Post Thyroidectomy Scanning: 12-15 MHz, 8MHz curved Patient Position Supine with neck extended Elevating the head 20o in obese patients may help Neck rotation Image optimization

Image Optimization:

Post Thyroidectomy Scanning: 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

Zone Landmarks: ZONES LANDMARKS NODAL GROUP 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 Submandibular nodes IIA Anterior or medial to the interior jugular vein but Lateral/posterior to the submandibular gland. Superior to the hyoid bone Upper internal jugular chain. More superiorly, the parotid nodes. IIB Posterior to the interior jugular vein III From the level of the hyoid bone inferiorly to the cricoid arch. Lateral to the common carotid artery. Middle internal jugular chain IV From the level of the cricoid arch inferiorly to the level of the clavicle. Lateral to the common carotid artery. Lower internal jugular chain VA Posterior to the sternocleidomastoid muscle, from the base of the skull to the cricoid arch Supraclavicular fossa/posterior triangle (spinal accessory chain and transverse cervical chain VB Posterior to the sternocleidomastoid muscle from the croicoid arch to the level of the clavicle VI Anterior/medial to the common carotid arteries from the level of the hyoid to the manubrium Anterior cervical nodes, pre and paratracheal VII Anterior/medial to the common carotid arteries, inferior to the sternal notch Anterior, upper mediastinal nodes Sup Clav Lateral to the common carotid artery. At or inferior to the clavicle Supraclavicular nodes

Cervical Lymph 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

Normal Lymph Nodes: 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

Abnormal Lymph Nodes: 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

Lymph Node Doppler: 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

Zone 6 Abnormalities: 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

Zone 1: 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

Zone 6: 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

Zone 2: 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

Zone 3: 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

Zone 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

Zone 7/Notch: 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

Supraclavicular: Lateral to the CCA At or inferior to the clavicle Nodal group: supraclavicular nodes

Zone 5: Posterior to sternocleidomastoid, superior to clavicle Nodal group: supraclavicular fossa, posterior triangle Uncommon location for PTC recurrence

University of Colorado Hospital Protocol: 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

Common Pitfalls: 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

Mixed or peripheral flow Cystic in advanced disease Lymph Node Summary: Normal: Malignant: 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.