J Korean Soc Endocrinol.  1999 Sep;14(3):520-530.

FDG-PET as a Predictor of Recurrence with 131I Scan Negative Differentiated Thyroid Cancer: An Evaluation Compared with Pathologic Findings

Affiliations
  • 1Division of Endocrinology and Metabolism, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 2Department of Nuclear Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 3Department of General Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
  • 4Department of Nuclear Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.

Abstract

BACKGROUND
FDG-PET has been suggested to have a supplementary role in localizing recurred sites of differentiated thyroid carcinoma. This study was performed to show whether FDG-PET is feasible as an alternative diagnostic modality for patients with I-131 scan negative thyroid carcinoma by verification of post-surgical pathology findings.
METHODS
Eighteen patients of papillary thyroid carcinoma (M:F=4:14, age 41+/-16 year) who had total thyroidectomy and I-131 ablation therapy were included. All patients showed negative I-131 scan on therapeutic dose but they were suspected as disease recurrence because of elevated serum Tg or anti-Tg Ab during follow-up periods. FDG-PET was performed, and then cervical lymph node dissection on either side or both sides of the neck was done according to FDG-PET results.
RESULTS
A total of 77 cervical lymph node groups were dissected in 18 patients; internal jugular chain 49, spinal accessory 9, jugulodigastric 5, anterior jugular 4, paratracheal 3, supraclavicular 2, and others 5. Forty eight lymph node groups revealed metastatic papillary carcinoma on pathology and their largest diameter ranged from 0.4 to 7.0cm (1.2+/-0.7cm). All patients had at least one malignant lymph node group. FDG-PET detected 37 among 48 malignant lymph nodes (sensitivity 77%), and their count ratio ranged 1.7-31.1 (6.1+/-6.3). Among the 30 malignant lymph nodes less than 1cm, FDG-PET detected 20 lymph nodes. Of the 29 lymph node groups without malignant cells, FDG-PET was also negative in 24 groups (specificity S3%). Positive predictive value of FDG-PET on I-131 scan negative differentiated thyroid carcinoma was 88%; negative predictive value was 69%.
CONCLUSION
FDG-PET has been confirmed as a valuable diagnostic modality to detect cervical lymph nodes of differentiated thyroid carcinoma who are suspicious for recurrence but with negative I-131 scan, by pathologic findings.


MeSH Terms

Carcinoma, Papillary
Follow-Up Studies
Humans
Lymph Node Excision
Lymph Nodes
Neck
Pathology
Recurrence*
Thyroglobulin
Thyroid Gland*
Thyroid Neoplasms*
Thyroidectomy
Thyroglobulin
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