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Vol 17, No 2 (2014)
Original articles
Published online: 2014-07-31
Submitted: 2014-04-01
Accepted: 2014-06-10
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The role of 18F-Fluorodeoxyglucose Positron Emission Tomography in patients with suspected recurrence or metastatic differentiated thyroid carcinoma with elevated serum thyroglobulin and negative I-131 whole body scan

Tomasz Trybek, Aldona Kowalska, Jacek Lesiak, Jacek Młynarczyk
DOI: 10.5603/NMR.2014.0023
·
Nucl. Med. Rev 2014;17(2):87-93.

open access

Vol 17, No 2 (2014)
Original articles
Published online: 2014-07-31
Submitted: 2014-04-01
Accepted: 2014-06-10

Abstract

BACKGROUND: The aim of this study is to evaluate the role of 18F-FDG PET/CT in the detection of recurrence or distant metastasis in patients with differentiated thyroid carcinoma (DTC) with elevated serum thyroglobulin (Tg) and negative 131I whole-body scan.

MATERIAL AND METHODS: The study included 19 patients (13 female, 6 male, average age 64 years) with DTC after total thyroidectomy and 131I ablation therapy that had elevated stimulated Tg and negative whole-body radioiodine scan. In all patients, standard imaging methods showed no suspicious changes. 18F-FDG PET/CT was performed after TSH stimulation with rhTSH or withdrawal of thyroid hormone. An evaluation of the dependence of the result of 18F-FDG PET/CT on the stimulated Tg levels was made accordingly. The statistical analysis was performed using Kruskal-Wallis test and ROC curves.

RESULTS: Based on the results of the study 18F-FDG PET/CT in 6 patients, the suspicion of metastasis involved: the cervical lymph nodes (3 patients, ~16%) and lungs (3 patients, ~16%). The patients underwent surgery. The histopathology confirmed metastatic thyroid cancer in all cases. High levels of TSH-stimulated Tg (Tg from 32 to >300 ng/ml, median of 59.7 ng/ml) in patients were reported. The group of remaining 13 patients (~68%) with negative 18F-FDG PET/CT had low levels of TSH-stimulated Tg (Tg of from 1.76 to 10.2 ng/ml, median of 4.0 ng/ml). A particular correlation was observed between 18F-FDG PET positivity and stimulated Tg levels. The receiver operating characteristic curve (ROC) analysis demonstrated a stimulated Tg cut-off of 28.5 ng/ml with 100% sensitivity and specificity. Stimulated Tg has a large and statistically significant (p<0.0001) accuracy in the detection of recurrence/metastasis.

CONCLUSION: 1. 18F-FDG PET/CT is useful in the diagnosis of radioiodine-negative DTC in patients with high levels of stimulated Tg. 2. The sensitivity of 18F-FDG PET/CT increases with stimulated Tg levels. At stimulated Tg > 28.5 ng/ml, the sensitivity of the study reaches 100%.

 

Abstract

BACKGROUND: The aim of this study is to evaluate the role of 18F-FDG PET/CT in the detection of recurrence or distant metastasis in patients with differentiated thyroid carcinoma (DTC) with elevated serum thyroglobulin (Tg) and negative 131I whole-body scan.

MATERIAL AND METHODS: The study included 19 patients (13 female, 6 male, average age 64 years) with DTC after total thyroidectomy and 131I ablation therapy that had elevated stimulated Tg and negative whole-body radioiodine scan. In all patients, standard imaging methods showed no suspicious changes. 18F-FDG PET/CT was performed after TSH stimulation with rhTSH or withdrawal of thyroid hormone. An evaluation of the dependence of the result of 18F-FDG PET/CT on the stimulated Tg levels was made accordingly. The statistical analysis was performed using Kruskal-Wallis test and ROC curves.

RESULTS: Based on the results of the study 18F-FDG PET/CT in 6 patients, the suspicion of metastasis involved: the cervical lymph nodes (3 patients, ~16%) and lungs (3 patients, ~16%). The patients underwent surgery. The histopathology confirmed metastatic thyroid cancer in all cases. High levels of TSH-stimulated Tg (Tg from 32 to >300 ng/ml, median of 59.7 ng/ml) in patients were reported. The group of remaining 13 patients (~68%) with negative 18F-FDG PET/CT had low levels of TSH-stimulated Tg (Tg of from 1.76 to 10.2 ng/ml, median of 4.0 ng/ml). A particular correlation was observed between 18F-FDG PET positivity and stimulated Tg levels. The receiver operating characteristic curve (ROC) analysis demonstrated a stimulated Tg cut-off of 28.5 ng/ml with 100% sensitivity and specificity. Stimulated Tg has a large and statistically significant (p<0.0001) accuracy in the detection of recurrence/metastasis.

CONCLUSION: 1. 18F-FDG PET/CT is useful in the diagnosis of radioiodine-negative DTC in patients with high levels of stimulated Tg. 2. The sensitivity of 18F-FDG PET/CT increases with stimulated Tg levels. At stimulated Tg > 28.5 ng/ml, the sensitivity of the study reaches 100%.

 

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Keywords

18F-FDG PET/CT, differentiated thyroid cancer, radioactive-negative, elevated human serum thyroglobulin

About this article
Title

The role of 18F-Fluorodeoxyglucose Positron Emission Tomography in patients with suspected recurrence or metastatic differentiated thyroid carcinoma with elevated serum thyroglobulin and negative I-131 whole body scan

Journal

Nuclear Medicine Review

Issue

Vol 17, No 2 (2014)

Pages

87-93

Published online

2014-07-31

DOI

10.5603/NMR.2014.0023

Bibliographic record

Nucl. Med. Rev 2014;17(2):87-93.

Keywords

18F-FDG PET/CT
differentiated thyroid cancer
radioactive-negative
elevated human serum thyroglobulin

Authors

Tomasz Trybek
Aldona Kowalska
Jacek Lesiak
Jacek Młynarczyk

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