18F-FDG-PET/CT in the diagnosis of paraneoplastic neurological syndromes: a retrospective analysis.

ABSTRACT

OBJECTIVES: Paraneoplastic neurological syndromes (PNS) constitute a challenging diagnostic problem, as the underlying tumour often remains unidentified for a long time, even with frequent conventional diagnostic procedures. For appropriate patient management timely identification of the tumour is critical. We evaluated the value of (18)F-FDG-PET/CT in the investigation of PNS. METHODS: The case notes of 46 consecutive patients with clinically suspected PNS who underwent (18)F-FDG-PET/CT were reviewed retrospectively and the performance of PET/CT for detecting underlying tumours was assessed. RESULTS: PET/CT detected foci of increased (18)F-FDG uptake in 10 out of 46 patients. In six of these 10 patients combined PET/CT identified the underlying disease four patients suffered from PNS; vasculitic and local metastatic disease was detected in two other patients. CONCLUSIONS: Based on our results, we believe that the role of positron emission tomography in the detection of occult neoplasms in patients with PNS has been overestimated in the past. In clinical practice, PNS is far more often suspected than proven. In our study combined PET/CT identified malignancy as the underlying cause of suspected PNS in only 8.7% (4/46). We believe that combined PET/CT should be reserved for stringently selected patients with a high clinical index of suspicion for PNS and after conventional imaging techniques fail to detect a tumour.