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Erschienen in:
12.03.2018 | Musculoskeletal
Vertebral metastases from neuroendocrine tumours: How to avoid false positives on 68Ga-DOTA-TOC PET using CT pattern analysis?
Erschienen in: European Radiology | Ausgabe 9/2018
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Objectives
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).
Methods
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.
Results
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.
Conclusions
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.
Key Points
• 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.