18f-Fluorodeoxyglucose Positron-Emission Tomography for the Investigation of Malignancy in Patients with Suspected Paraneoplastic Neurologic Syndromes and Negative or Indeterminate Conventional Imaging: A Retrospective Analysis of the Ontario Pet Access Program, with Systematic Review and Meta-Analysis

Objective: Paraneoplastic neurologic syndrome (pns) is a rare condition indirectly caused by an underlying malignancy. In many cases, the malignancy is occult at the time of the pns diagnosis, and the optimal diagnostic modality to detect the underlying tumour is unclear. In the present study, we aimed to assess the utility of 18F-fluorodeoxyglucose positron-emission tomography (fdg-pet) or pet integrated with computed tomography (pet/ct) in the investigation of these patients. Methods: We retrospectively analyzed data from the PET Access Program (pap) database in the province of Ontario to identify patients who underwent fdg-pet/ct imaging as part of a workup for pns. In all patients, prior conventional imaging was negative or indeterminate. To determine the diagnostic accuracy of fdg-pet/ct, data about demographics, presenting symptoms, and biochemical and radiologic workup, including fdg-pet/ct imaging results, were compared with data collected by the Ontario Cancer Registry (ocr). A systematic review of the literature and meta-analysis using our study inclusion criteria were performed for studies of fdg-pet accuracy. Results: Of 29 patients identified in the pap database, 9 had fdg-pet/ct results suspicious for malignancy. When correlated with data from the ocr, 5 fdg-pet/ct results were informative, resulting in a detection rate of 17%. Local sensitivity and specificity were 0.83 and 0.83 respectively. Two studies meeting our criteria were identified in the literature. The pooled sensitivity and specificity from the literature and local data were 0.88 and 0.90 respectively. Conclusions: When investigating for underlying malignancy in patients with suspected pns and negative conventional imaging, pet has high sensitivity and specificity.