Impact of combined FDG-PET/CT and MRI on the detection of local recurrence and nodal metastases in thyroid cancer.
BACKGROUND
Suspected recurrence of thyroid carcinoma is a diagnostic challenge when findings of both a radio iodine whole body scan and ultrasound are negative. PET/CT and MRI have shown to be feasible for detection of recurrent disease. However, the added value of a consensus reading by the radiologist and the nuclear medicine physician, which has been deemed to be helpful in clinical routines, has not been investigated. This study aimed to investigate the impact of combined FDG-PET/ldCT and MRI on detection of locally recurrent TC and nodal metastases in high-risk patients with special focus on the value of the multidisciplinary consensus reading.


METHODS
Forty-six patients with suspected locally recurrent thyroid cancer or nodal metastases after thyroidectomy and radio-iodine therapy were retrospectively selected for analysis. Inclusion criteria comprised elevated thyroglobulin blood levels, a negative ultrasound, negative iodine whole body scan, as well as combined FDG-PET/ldCT and MRI examinations. Neck compartments in FDG-PET/ldCT and MRI examinations were independently analyzed by two blinded observers for local recurrence and nodal metastases of thyroid cancer. Consecutively, the scans were read in consensus. To explore a possible synergistic effect, FDG-PET/ldCT and MRI results were combined. Histopathology or long-term follow-up served as a gold standard. For method comparison, sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were calculated.


RESULTS
FDG-PET/ldCT was substantially more sensitive and more specific than MRI in detection of both local recurrence and nodal metastases. Inter-observer agreement was substantial both for local recurrence (κ = 0.71) and nodal metastasis (κ = 0.63) detection in FDG-PET/ldCT. For MRI, inter-observer agreement was substantial for local recurrence (κ = 0.69) and moderate for nodal metastasis (κ = 0.55) detection. In contrast, FDG-PET/ldCT and MRI showed only slight agreement (κ = 0.21). However, both imaging modalities identified different true positive results. Thus, the combination created a synergistic effect. The multidisciplinary consensus reading further increased sensitivity, specificity, and diagnostic accuracy.


CONCLUSIONS
FDG-PET/ldCT and MRI are complementary imaging modalities and should be combined to improve detection of local recurrence and nodal metastases of thyroid cancer in high-risk patients. The multidisciplinary consensus reading is a key element in the diagnostic approach.
Department of Radiology, Diagnostic and Interventional Neuroradiology, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, D-72076, Tübingen, Germany. johann-martin.hempel@uni-tuebingen.de.|Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany. johann-martin.hempel@uni-tuebingen.de.
Johann-Martin
http://orcid.org/0000-0002-9647-5136
JM
Hempel
Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Roman
R
Kloeckner
Department of Nuclear Medicine, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Sandra
S
Krick
Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Daniel
D
Pinto Dos Santos
Department of Diagnostic and Interventional Radiology, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Simin
S
Schadmand-Fischer
Department of Otolaryngology and Head and Neck Surgery, AMEOS Hospital Haldensleben, Kiefholzstr. 4 & 27, D-39340, Haldensleben, Germany.
Patrick
P
Boeßert
Department of Radiology, Diagnostic and Interventional Neuroradiology, Eberhard Karls University Tübingen, Hoppe-Seyler-Str. 3, D-72076, Tübingen, Germany.|Department of Neuroradiology, National Hospital of Neurology and Neurosurgery, University College London Hospitals, London, United Kingdom.
Sotirios
S
Bisdas
Department of Endocrinology and Metabolism, I. Medical Clinic, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Matthias M
MM
Weber
Department of Endocrinology and Metabolism, I. Medical Clinic, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Christian
C
Fottner
Clinic of General, Visceral- and Transplantation Surgery, Endocrine Surgery Section, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Thomas J
TJ
Musholt
Department of Nuclear Medicine, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Mathias
M
Schreckenberger
Department of Nuclear Medicine, Johannes Gutenberg-University Medical Center, Langenbeckstr. 1, D-55131, Mainz, Germany.
Matthias
M
Miederer
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D006801:Humans; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis*; D000072078:Positron Emission Tomography Computed Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000175:diagnosis* / Q000556:secondary
D019788:Fluorodeoxyglucose F18
Consensus reading; Iodine-negative; Lymph node metastases; MRI; Negative ultrasound; Nodal metastases; PET/CT; Recurrent thyroid cancer; Recurrent thyroid carcinoma; Thyroid cancer