CT Detection of Metastatic Lymphadenopathy in Papillary Thyroid Cancer
CT Detection of Metastatic Lymphadenopathy in Papillary Thyroid Cancer
Localized thyroid cancer is potentially curable. Before thyroid surgery, an ultrasound test
 is done to see if cancer has spread to the lymph nodes in the neck. Excellent for evaluation
 of the thyroid gland, this test has limitations in evaluating larger anatomic areas, like all
 groups of lymph nodes in the neck. It has a limited area of coverage making it difficult to
 define an area of interest, depends on the skill level of the person performing it, and is
 difficult to exactly reproduce on follow-up. For these reasons, CT is often performed in
 these patients but without intravenous (IV) contrast since iodine-based contrast agents may
 saturate the thyroid, limiting the usefulness of other iodine-based diagnostic and treatment
 options. However, contrast-CT can give more detailed information about tumor spread including
 spread to lymph nodes. We aim to determine if use of IV contrast agent during CT leads to
 earlier and more accurate detection of lymph node disease from thyroid cancer.
Papillary thyroid cancer represents 75% of all epithelial thyroid malignancies. Imaging not
 only delineates the primary tumour within the thyroid gland, but also helps assess lymph
 nodal metastatic disease helping guide the extent of surgical neck dissection.
 Ultrasonography (US) is the current imaging standard (American Thyroid Association
 guidelines). However, US is limited by operator skills and lacks specific anatomic references
 essential to plan surgery. CT is performed to address these issues, often without intravenous
 (IV) contrast for fear of saturating thyroid tissue with iodine present in it, thus rendering
 iodine-labeled nuclear testing/treatment ineffective for a finite period of time. But
 post-contrast nodal enhancement is a predominant morphologic feature of suspicious
 lymphadenopathy in papillary thyroid cancer, and contrast-CT can facilitate an earlier
 detection. Iodine-saturation is not a concern in these patients as its concentration will
 normalize during recovery.

 In pre-surgical thyroidectomy patients with proven papillary thyroid cancer, the use of
 intravenous (IV) CT contrast improves the reliability and accuracy of suspicious head and
 neck lymph node detection, in comparison to CT without IV contrast.

 This study will help define the accuracy and reliability of intravenous (IV) contrast use in
 the detection of metastatic neck lymph nodes from papillary thyroid cancer. Improved
 detection of suspicious metastatic lymphadenopathy in papillary thyroid cancer will directly
 impact the patient's management since the surgical plan will be based upon the detection of
 these suspicious lymph nodes. CT imaging provides an anatomically relevant approach to
 surgery and is consistently reproducible, thus providing direct benefits to the pre-surgical
 assessment. Ultimately, this will result in decreased nodal recurrences within the neck.
Inclusion Criteria:

 -  Pre-operative thyroidectomy patients with pathology-proven papillary thyroid cancer
 (PTC) needing lymph node staging for potential neck dissection.

 Exclusion Criteria:

 -  Patients with history of prior surgery within the head and neck.

 -  Patients with history of prior radiation to the head and neck.

 -  Patients with history of lymphoma, leukemia, or other lymphoproliferative disorders
 affecting the head and neck.

 -  Pregnant/breast feeding patients (by question).