Widespread Skeletal Metastases in Medullary Thyroid Carcinoma: Diagnostic Superiority of 68 Ga-FAPI PET/CT Over Somatostatin Receptor-Targeted Imaging.
68 Ga-FAPI PET/CT may be more effective than SSTR-targeted imaging for detecting skeletal metastases in medullary thyroid carcinoma, but further research is needed.
Where it sits
this study against the rest of the octreotide corpusSummary and findings
A 78-year-old woman with medullary thyroid carcinoma showed elevated serum calcitonin levels despite previous treatments. 99m Tc-octreotide imaging did not detect skeletal metastases, whereas 68 Ga-FAPI PET/CT identified extensive skeletal involvement. This case suggests FAP-targeted imaging may be superior to SSTR-targeted imaging for detecting skeletal metastases in MTC.
Abstract
A 78-year-old woman with medullary thyroid carcinoma (MTC) demonstrated persistently elevated serum calcitonin despite prior surgery and radiotherapy. 99m Tc-octreotide imaging failed to detect skeletal metastases, while 68 Ga-FAPI PET/CT revealed extensive skeletal involvement. Biochemical markers were disproportionately low relative to disease burden, consistent with a low-secretory MTC. This case highlights the limitations of SSTR-targeted imaging in MTC and underscores the diagnostic superiority of FAP-targeted imaging.
Background
Medullary thyroid carcinoma (MTC) is a type of thyroid cancer that can be challenging to monitor and treat, particularly when it metastasizes to the skeleton. Traditional imaging techniques, like those targeting somatostatin receptors, may not always detect metastatic spread effectively. This study explores the potential of 68 Ga-FAPI PET/CT imaging as a more sensitive diagnostic tool for detecting skeletal metastases in MTC.
Methods
This is a case report of a 78-year-old woman with medullary thyroid carcinoma. The patient had persistently elevated serum calcitonin levels despite undergoing surgery and radiotherapy. Imaging was performed using both 99m Tc-octreotide and 68 Ga-FAPI PET/CT to assess skeletal metastases.
Results
The 99m Tc-octreotide imaging failed to detect any skeletal metastases in the patient. In contrast, the 68 Ga-FAPI PET/CT scan revealed extensive skeletal involvement. The biochemical markers were found to be disproportionately low compared to the disease burden, indicating a low-secretory form of MTC.
Interpretation
This case suggests that 68 Ga-FAPI PET/CT may offer superior diagnostic capabilities over traditional SSTR-targeted imaging for detecting skeletal metastases in MTC. However, as a single case report, these findings need to be validated in larger studies. The clinical significance of these findings is uncertain without broader evidence.
Key findings
- 78-year-old woman with medullary thyroid carcinoma.
- Persistently elevated serum calcitonin despite prior surgery and radiotherapy.
- 99m Tc-octreotide imaging failed to detect skeletal metastases.
- 68 Ga-FAPI PET/CT revealed extensive skeletal involvement.
- Biochemical markers were disproportionately low relative to disease burden.
Limitations
- Single case report.
- Findings may not be generalizable.
- No quantitative results reported.
- Imaging findings specific to low-secretory MTC.