Evaluating Positron Emission Tomography Use in Differentiated Thyroid Cancer

Area of Science:

• Oncology
• Nuclear Medicine
• Diagnostic Imaging

Background:

• Positron emission tomography (PET) scan utilization has significantly increased in differentiated thyroid cancer (DTC) patients since 2004.
• The reasons for this increased use were unclear from previous data.
• This study evaluated the indications and outcomes of PET scans in DTC patients at an academic institution.

Purpose of the Study:

• To evaluate the indications for positron emission tomography (PET) scans in differentiated thyroid cancer (DTC) patients.
• To assess the outcomes and impact on management of PET scans performed in DTC patients.
• To characterize the positivity rate and disease localization identified by PET scans in DTC.

Main Methods:

• A retrospective cohort study of DTC patients who underwent surgery between 2006 and 2011 at an academic medical center.
• Identification of patients who underwent PET scans, with subsequent evaluation of indications, positivity rates, and impact on patient management.
• Characterization of positive PET scan findings, including disease location and comparison with other imaging modalities.

Main Results:

• Of 585 DTC patients, 111 (19%) underwent 200 PET scans.
• Common indications included elevated thyroglobulin with negative radioiodine scan (26%), follow-up (28.5%), and evaluation of extent of disease (16.5%).
• PET scans were positive in 62% of cases, identifying disease in lymph nodes (105 scans), thyroid bed (25 scans), and lungs (28 scans). Management was altered in 29.5% of cases.

Conclusions:

• PET scans were utilized in 19% of DTC patients at this academic center.
• Indications ranged from conventional (e.g., elevated thyroglobulin) to controversial (e.g., evaluating extent of disease).
• PET scan results influenced management decisions in approximately 30% of patients.