[(68)Ga]-Pentixafor PET/CT for CXCR4-Mediated Imaging of Vestibular Schwannomas

We have recently demonstrated CXCR4 overexpression in vestibular schwannomas (VS). This study investigated the feasibility of CXCR4-directed positron emission tomography/computed tomography (PET/CT) imaging of VS using the radiolabeled chemokine ligand [(68)Ga]Pentixafor. Methods: 4 patients with 6 primarily diagnosed or pre-treated/observed VS were enrolled. All subjects underwent [(68)Ga]Pentixafor PET/CT prior to surgical resection. Images were analyzed visually and semi-quantitatively for CXCR4 expression including calculation of tumor-to-background ratios (TBR). Immunohistochemistry served as standard of reference in three patients. Results: [(68)Ga]Pentixafor PET/CT was visually positive in all cases. SUV(mean) and SUV(max) were 3.0 ± 0.3 and 3.8 ± 0.4 and TBR(mean) and TBR(max) were 4.0 ± 1.4 and 5.0 ± 1.7, respectively. Histological analysis confirmed CXCR4 expression in tumors. Conclusion: Non-invasive imaging of CXCR4 expression using [(68)Ga]Pentixafor PET/CT of VS is feasible and could prove useful for in vivo assessment of CXCR4 expression.