Complementary roles of tumour specific PET tracer 18F-FAMT to 18F-FDG PET/CT for the assessment of bone metastasis

Purpose

The usefulness of ¹⁸F-FDG PET/CT for bone metastasis evaluation has already been established. The amino acid PET tracer ¹⁸F]-3-fluoro-alpha-methyl tyrosine (¹⁸F-FAMT) has been reported to be highly specific for malignancy. We evaluated the additional value of ¹⁸F-FAMT PET/CT to complement ¹⁸F-FDG PET/CT in the evaluation of bone metastasis.

Methods

This retrospective study included 21 patients with bone metastases of various cancers who had undergone both ¹⁸F-FDG and ¹⁸F-FAMT PET/CT within 1 month of each other. ¹⁸F-FDG-avid bone lesions suspicious for malignancy were carefully selected based on the cut-off value for malignancy, and the SUVmax of the ¹⁸F-FAMT in the corresponding lesions were evaluated.

Results

A total of 72 ¹⁸F-FDG-positive bone lesions suspected to be metastases in the 21 patients were used as the reference standard. ¹⁸F-FAMT uptake was found in 87.5 % of the lesions. In the lesions of lung cancer origin, the uptake of the two tracers showed a good correlation (40 lesions, r?=?0.68, P?<?0.01). Bone metastatic lesions of oesophageal cancer showed the highest average of ¹⁸F-FAMT uptake. Bone metastatic lesions of squamous cell carcinoma showed higher ¹⁸F-FAMT uptake than those of adenocarcinoma. No significant difference in ¹⁸F-FAMT uptake was seen between osteoblastic and osteolytic bone metastatic lesions.

Conclusion

The usefulness of ¹⁸F-FAMT PET/CT for bone metastasis detection regardless of the lesion phenotype was demonstrated. The fact that ¹⁸F-FAMT uptake was confirmed by ¹⁸F-FDG uptake suggests that ¹⁸F-FAMT PET/CT has the potential to complement ¹⁸F-FDG PET/CT for the detection of bone metastases.