Sir,

We thank Vatankulu et al. [1] for their interest in our recent paper in the European Journal of Nuclear Medicine and Molecular Imaging on FDG PET/CT in patients with suspected paraneoplastic syndromes (PNS) [2]. As discussed in their comment, the paraneoplastic antibodies may have some merit in certain settings, but also seem controversial as addressed by Vatankulu et al. in their mentioned recent paper (which was not available at the time of the literature search for our paper). They concluded that the value of FDG PET/CT is independent of the presence of paraneoplastic antibodies [3]. We opted not to address the paraneoplastic antibodies for several reasons. Firstly, they only apply to the neurological syndromes in suspicious PNS, which were the focus in most other studies on FDG PET/CT in PNS [2]. However, we wanted to specifically assess the value of FDG PET/CT in an unselected, heterogeneous population of PNS patients, and neurological PNS accounted for less than half of our patients, and only 25 % of the patients with a cancer diagnosis initially presented with neurological PNS. Secondly, for practical reasons we included patients from a clinical database who underwent a PET/CT scan at our institution. Because of legal constraints we were unable to identify patients with suspected PNS unless they had undergone a PET/CT scan, and therefore we could not assess the true value of paraneoplastic antibodies in these patients.

We agree with Vatankulu et al. that the most prominent characteristics of our study were the heterogeneity of the patients, the long follow-up period, and the high negative predictive value of FDG PET/CT in the setting of PNS. Thus, in line with what has been suggested in the literature and most recently by Vatankulu and coworkers, we consider FDG PET/CT a potent modality in suspected PNS, but not only in well-selected patients, but also in populations with more heterogeneous appearances, which in our experience is exactly what characterizes patients with suspected PNS.