1. Post operative ultrasound evaluation of the neck in Thyroid cancer patients
Stephen D. Chapman, D.O.
Lansing Radiology Associates, P.C.

2. Well differentiated thyroid cancer
Thyroid cancer is the most common endocrine cancer
Papillary and follicular types are classified as well-differentiated thyroid arising from thyroid follicular cells.
Account for approximately 80% to 90% of all thyroid cancers.

3. Well differentiated thyroid cancer
Sonography can detect recurrent disease as small as 2 to 3 mm; before they become palpable and visualized with other imaging modalities or before laboratory values become abnormal

4. Lymph node anatomy
Normal lymph nodes are composed of a cortex and a medulla covered by a fibrous capsule
Each lymph node contains a main artery that enters at the hilus and branches into multiple arterioles.
Cortex contains tightly packed lymphocytes and is hypoechoic.
Medulla is made of trabeculae and medullary cords and sinuses and is echogenic

5. Lymph node anatomy
Normal cervical lymph nodes are typically oblong, oval, cigar, or kidney bean shaped.
Reported size criteria are variable; normal nodes have a short- to long-axis ratio of less than 0.5.
The presence of an echogenic hilus is a strong predictor of a benign node

6. Lymph node anatomy
Small nodes, less than 5 mm, often appear to be avascular.
Flow within the larger submandibular and upper cervical lymph nodes may be increased.
Peripheral vascularity should not be seen in normal lymph nodes.

7. Lymph node anatomy
Multiple characteristics should be visualized to confirm benignity.
A sole benign criterion is not sufficient for an accurate diagnosis.

8. Well differentiated thyroid cancer
When recurrent disease is present, the lymph node will lose its ovoid, elliptical shape and become more rounded.
Lymph nodes that are increasing in size on serial sonograms should be concerning for metastases.

9. Well differentiated thyroid cancer
In addition to a lack of a fatty hilum, malignant lymph nodes typically are hypoechoic when compared with the surrounding tissues. This is the case with medullary thyroid cancer and lymphoma.
With recurrent papillary thyroid cancer, however, the lymph node is commonly hyperechoic. This hyperechoic appearance is likely due to the presence of thyroglobulin within the lymph node.
Peripheral or mixed (peripheral and hilar) flow has been shown to be highly suggestive of malignancy.

10. Well differentiated thyroid cancer
Calcifications are typically small (microcalcifications) and peripherally located.
Shadowing from the calcification may or may not be visualized.
When the cervical lymph node becomes cystic, it is highly suggestive of recurrent papillary thyroid cancer
The cystic change is caused by necrosis secondary to tumor invasion.

11. Figure 1. Normal oval-shaped lymph node with an echogenic hilum located in zone III.

12. Figure 3. (A, B) Reactive lymph nodes within zone II in two different patients. It is not unusual to see larger lymph nodes near the submandibular gland.

13. Figure 2. Jugular lymph nodes are commonly located in chains
Figure 2. Jugular lymph nodes are commonly located in chains. Each lymph node should be evaluated for normal characteristics. These three normal lymph nodes with echogenic hilum are located within zone IV.

14. Figure 4. Normal lymph node within zone VI
Figure 4. Normal lymph node within zone VI. Note the hypoechoic cortex and echogenic hilum.

15. Precise anatomic localization with cervical US of WBS-depicted recurrence.
Precise anatomic localization with cervical US of WBS-depicted recurrence. (a) Diagnostic WBS image shows focus of radioiodine uptake in right “thyroid bed” (arrow), which is suspicious for local recurrence. Lesion is poorly localized owing to inherent limited resolution of 131I WBS. (b) Cervical US image shows partially cystic right level IV lymph node (arrow).
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

16. Precise anatomic localization with cervical US of WBS-depicted recurrence.
Precise anatomic localization with cervical US of WBS-depicted recurrence. (a) Diagnostic WBS image shows focus of radioiodine uptake in right “thyroid bed” (arrow), which is suspicious for local recurrence. Lesion is poorly localized owing to inherent limited resolution of 131I WBS. (b) Cervical US image shows partially cystic right level IV lymph node (arrow).
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

17. Technique
The patient is positioned supine with the neck hyperextended.
Typically, a 10 to12-MHz or higher linear array transducer is used.

18. Landmarks and Zones
Table 1. Anatomical Landmarks for Each Zone of the Neck22–24
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 Upper internal jugular chain; more
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
Supraclavicular Lateral to the common carotid artery; at or inferior to the clavicle Supraclavicular nodes

20. Standardized neck imaging classification scheme for reporting findings in lymph nodes is critical for effective communication with referring clinicians and surgeons.
Standardized neck imaging classification scheme for reporting findings in lymph nodes is critical for effective communication with referring clinicians and surgeons. (Reprinted, with permission, from reference 61.)‏
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

21. Figure 6. Chain of abnormal, rounded, hyperechoic lymph nodes within zone III. Note the lack of an echogenic hilum

22. US images of clustered malignant lymph nodes at (a) conventional and (b) compound imaging. Microcalcifications in smaller lymph node (white arrows) and cystic degeneration of larger node (black arrows) are specific findings of DTC nodal metastases.
US images of clustered malignant lymph nodes at (a) conventional and (b) compound imaging. Microcalcifications in smaller lymph node (white arrows) and cystic degeneration of larger node (black arrows) are specific findings of DTC nodal metastases. Note decrease in low-level echoes in the cystic node and increased conspicuity of microcalcifications when compound imaging is used.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

23. US images of clustered malignant lymph nodes at (a) conventional and (b) compound imaging. Note decrease in low-level echoes in the cystic node and increased conspicuity of microcalcifications when compound imaging is used.
US images of clustered malignant lymph nodes at (a) conventional and (b) compound imaging. Microcalcifications in smaller lymph node (white arrows) and cystic degeneration of larger node (black arrows) are specific findings of DTC nodal metastases. Note decrease in low-level echoes in the cystic node and increased conspicuity of microcalcifications when compound imaging is used.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

24. US image of 6-mm malignant left level IV lymph node.
Round and echogenic
US image of 6-mm malignant left level IV lymph node. Note rounded configuration and hyperechogencity of node (arrow). With optimal US technique, very small-volume recurrence can be readily identified and sampled, if neces-sary.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

25. US features of nodal recurrence
US features of nodal recurrence. Two closely opposed nodal metastases smaller than 1 cm. Note cystic degeneration (arrow) and subtle microcalcifications (arrowhead). Small benign lymph node (*) was also confirmed after focused dissection. Note oblong shape and echogenic fatty hilum.
US features of nodal recurrence. (a) Two closely opposed nodal metastases smaller than 1 cm. Note cystic degeneration (arrow) and subtle microcalcifications (arrowhead). Small benign lymph node (*) was also confirmed after focused dissection. Note oblong shape and echogenic fatty hilum. (b) Malignant round echogenic lymph node. (c) Microcalcifications in PTC of right lobe and adjacent right level IV lymph node (arrows). (d) Cystic degeneration of large left level III lymph node (arrow). Thick septations and nodular solid components are typical of DTC recurrence.

26. US features of nodal recurrence.
Malignant round echogenic lymph node
US features of nodal recurrence. (a) Two closely opposed nodal metastases smaller than 1 cm. Note cystic degeneration (arrow) and subtle microcalcifications (arrowhead). Small benign lymph node (*) was also confirmed after focused dissection. Note oblong shape and echogenic fatty hilum. (b) Malignant round echogenic lymph node. (c) Microcalcifications in PTC of right lobe and adjacent right level IV lymph node (arrows). (d) Cystic degeneration of large left level III lymph node (arrow). Thick septations and nodular solid components are typical of DTC recurrence.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

27. US features of nodal recurrence.
Microcalcifications in PTC of right lobe and adjacent right level IV lymph node (arrows).
US features of nodal recurrence. (a) Two closely opposed nodal metastases smaller than 1 cm. Note cystic degeneration (arrow) and subtle microcalcifications (arrowhead). Small benign lymph node (*) was also confirmed after focused dissection. Note oblong shape and echogenic fatty hilum. (b) Malignant round echogenic lymph node. (c) Microcalcifications in PTC of right lobe and adjacent right level IV lymph node (arrows). (d) Cystic degeneration of large left level III lymph node (arrow). Thick septations and nodular solid components are typical of DTC recurrence.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

28. US features of nodal recurrence. Cystic degeneration
US features of nodal recurrence. Cystic degeneration. Thick septations and nodular solid components are typical of DTC recurrence.
US features of nodal recurrence. (a) Two closely opposed nodal metastases smaller than 1 cm. Note cystic degeneration (arrow) and subtle microcalcifications (arrowhead). Small benign lymph node (*) was also confirmed after focused dissection. Note oblong shape and echogenic fatty hilum. (b) Malignant round echogenic lymph node. (c) Microcalcifications in PTC of right lobe and adjacent right level IV lymph node (arrows). (d) Cystic degeneration of large left level III lymph node (arrow). Thick septations and nodular solid components are typical of DTC recurrence.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

29. Figure 8. Multiple examples of abnormal lymph nodes showing microcalcifications. (A) Complex lymph node that is recurrent papillary carcinoma by biopsy. (B) Hypoechoic lymph node with microcalcifications that was biopsy-proven recurrent medullary carcinoma. (C) Hyperechoic lymph node with microcalcifications. This lymph node was recurrent papillary carcinoma.

30. Figure 9. Multiple enlarged cystic lymph nodes extending from zone III to zone IV. Pathology confirmed recurrent papillary thyroid cancer.

31. Figure 10. Another example of an enlarged cystic lymph node within zone IV. Also note the multiple microcalcifications.

32. Figure 11. It is important to correlate sonography findings with the patient’s surgical history. In this case, the focal areas within the sternocleidomastoid muscle are autotransplanted parathyroid glands.

33. Figure 5. Normal hilar flow within a cervical lymph node.

34. Figure 7. (A, B) Abnormal, peripheral flow within an abnormal lymph node in two different patients. Also note the rounded, echogenic appearance, microcalcifications, and lack of an echogenic hilum.

35. Color Doppler US image of malignant lymph node demonstrates peripheral vascularity (arrows), in contrast to hilar vascularity typical of reactive lymph nodes.
Color Doppler US image of malignant lymph node demonstrates peripheral vascularity (arrows), in contrast to hilar vascularity typical of reactive lymph nodes.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

36. Well differentiated thyroid cancer
Zone VI masses can include postoperative scarring, muscle, necrosing fat, suture granulomas, parathyroid glands, lymph nodes, remnant tissue, and metastasis

37. (a) Transverse gadolinium-enhanced T1-weighted MR image shows enhancement of round right-sided level VI (arrow) and level IV lymph nodes (arrowheads), typical of recurrence.
(a) Transverse gadolinium-enhanced T1-weighted MR image shows enhancement of round right-sided level VI (arrow) and level IV lymph nodes (arrowheads), typical of recurrence. (b) Corresponding transverse unenhanced CT image also shows slightly enlarged lymph nodes. The need to avoid iodinated contrast material in these patients often decreases the conspicuity of cervical and mediastinal nodal metastases. (c) Transverse US image through right thyroid resection bed in same patient demonstrates the right level VI recurrence (arrow). C = common carotid artery, T = trachea. Additional central-compartment pretracheal tumor not apparent at either CT or MR imaging was also identified at US performed prior to focused dissection.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

38. Johnson N A , Tublin M E Radiology 2008;249:429-444
(a) Transverse gadolinium-enhanced T1-weighted MR image shows enhancement of round right-sided level VI (arrow) and level IV lymph nodes (arrowheads), typical of recurrence. (b) Corresponding transverse unenhanced CT image also shows slightly enlarged lymph nodes. The need to avoid iodinated contrast material in these patients often decreases the conspicuity of cervical and mediastinal nodal metastases. (c) Transverse US image through right thyroid resection bed in same patient demonstrates the right level VI recurrence (arrow). C = common carotid artery, T = trachea. Additional central-compartment pretracheal tumor not apparent at either CT or MR imaging was also identified at US performed prior to focused dissection.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

39. Johnson N A , Tublin M E Radiology 2008;249:429-444
(a) Transverse gadolinium-enhanced T1-weighted MR image shows enhancement of round right-sided level VI (arrow) and level IV lymph nodes (arrowheads), typical of recurrence. (b) Corresponding transverse unenhanced CT image also shows slightly enlarged lymph nodes. The need to avoid iodinated contrast material in these patients often decreases the conspicuity of cervical and mediastinal nodal metastases. (c) Transverse US image through right thyroid resection bed in same patient demonstrates the right level VI recurrence (arrow). C = common carotid artery, T = trachea. Additional central-compartment pretracheal tumor not apparent at either CT or MR imaging was also identified at US performed prior to focused dissection.
Johnson N A , Tublin M E Radiology 2008;249:
©2008 by Radiological Society of North America

40. Figure 12. Hypoechoic oval mass within zone VI
Figure 12. Hypoechoic oval mass within zone VI. The differential diagnosis includes recurrent disease, parathyroid, or abnormal lymph node.

41. Figure 13. Zone VI abnormalities
Figure 13. Zone VI abnormalities. (A) Hyperechoic oval mass within zone VI is a biopsy-proven recurrent papillary carcinoma. (B) A more hypoechoic mass deep within zone VI in another patient. This was also recurrent papillary carcinoma.

42. Figure 14. Small, hypoechoic area within zone VI
Figure 14. Small, hypoechoic area within zone VI. The differential diagnosis includes recurrent disease, parathyroid, abnormal lymph node, granuloma, or scarring.

43. Well differentiated thyroid cancer
US was found to be far more sensitive than WBS for the detection of local recurrence (sensitivity, 70% for US vs 20% for WBS); when thyroglobulin measurement was combined with US, the sensitivity and specificity were 96.2% and 100%, respectively, versus 92.7% and 100% for thyroglobulin measurement combined with WBS