Vertebral metastases from neuroendocrine tumours: How to avoid false positives on 68Ga-DOTA-TOC PET using CT pattern analysis?
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To develop criteria to improve discrimination between vertebral metastases from neuroendocrine tumours (NETs) and benign bone lesions on PET combined with CT using DOTA-D-Phe1-Tyr3-octreotide labelled with gallium-68 (68Ga-DOTA-TOC).
In 535 NET patients, 68Ga-DOTA-TOC PET/CT examinations were reviewed retrospectively for vertebral CT lesions and/or PET foci. For each vertebral PET abnormality, appearance on CT, biological volume (BV), standardized uptake value (SUVmax) and ratios to those of reference organs were determined. All vertebral abnormalities were characterized as a metastasis, a typical vertebral haemangioma (VH) or other benign lesion.
In 79 patients (14.8 %), we found 107 metastases, 34 VHs and 31 other benign lesions in the spine. The optimal cut-off values to differentiate metastases from benign lesions were BV ≥0.72 cm3, SUVmax ≥2, SUVmax ratio to a reference vertebra ≥2.1, to liver ≥0.28 and to spleen ≥0.14. They corresponded to lesion-based 68Ga-DOTA-TOC PET/CT sensitivity of 87 %, 98 %, 97 %, 99 % and 94 %, and specificity of 55 %, 100 %, 90 %, 97 %, 100 %, respectively.
The high sensitivity of 68Ga-DOTA-TOC-PET/CT in detecting NET vertebral metastases was confirmed; this study showed that specificity could be improved by combining CT features and quantifying 68Ga-DOTA-TOC uptake.
• Bone metastases in neuroendocrine tumours correlate with prognosis.
• Benign bone lesions may mimic metastases on 68 Ga-DOTA-TOC PET/CT imaging.
• The specific polka-dot CT pattern may be missing in some vertebral haemangiomas.
• Lesion atypical for haemangiomas can be better characterized by quantifying 68 Ga-DOTA-TOC uptake.
KeywordsNeuroendocrine tumours Haemangioma PET/CT Incidental findings Spinal neoplasms
Area under the curve
Magnetic resonance imaging
Negative predictive value
Ordered Subsets Expectation-Maximization
Positron emission tomography
Positive predictive value
Receiver operating characteristic
Standard of truth
Somatostatin receptors subtype 2
Standardized uptake value
Volume of interest
This study includes the data of a ‘Projet de recherche clinique’ PHRC P040303 sponsored by Assistance Publique-Hôpitaux de Paris monitored by Mrs Zakia Idir. We acknowledge the help of the Cancer Est Clinical Research Assistants during the clinical trial. We thank the referring physicians for their confidence and the medical technologists of our department for their commitment to PET/CT imaging. We thank Professor Ralph McCready for his assistance with editing the manuscript.
The authors state that this retrospective analysis of data of a prospective series has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Prof. J.N. Talbot.
Conflict of interest
The authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
One of the authors has significant statistical expertise.
No complex statistical methods were necessary for this paper.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional Review Board approval was obtained.
• diagnostic study
• performed at one institution
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