Molecular imaging of bone metastases using tumor-targeted tracers

Bone metastasis is a disastrous manifestation of most malignancies, especially in breast, prostate and lung cancers. Since asymptomatic bone metastases are not uncommon, early detection, precise assessment, and localization of them are very important. Various imaging modalities have been employed in the setting of diagnosis of bone metastasis, from plain radiography and bone scintigraphy to SPECT, SPECT/CT, PET/CT, MRI. However, each modality showed its own limitation providing accurate diagnostic performance. In this regard, various tumor-targeted radiotracers have been introduced for molecular imaging of bone metastases using modern hybrid modalities. In this article we review the strength of different cancer-specific radiopharmaceuticals in the detection of bone metastases. As shown in the literature, among various tumor-targeted tracers, Ga-68 DOTA-conjugated-peptides, Ga-68 PSMA, F-18 DOPA, F-18 galacto-RGD integrin, F-18 FDG, C-11/F-18 acetate, C-11/F-18 choline, In-111 octreotide, I-123/131 MIBG, Tc-99m MIBI, and Tl-201 have acceptable capabilities in detecting bone metastases depending on the cancer type. However, different study designs and gold standards among reviewed articles should be taken into consideration.