18 F-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.

Detection of extra-regional tumour recurrence with 18F-FDG-PET/CT in patients with recurrent gynaecological malignancies being considered for radical salvage surgery.

AIM: To compare the detection rate of extra-regional metastases in patients with recurrent gynaecological malignancies being considered for radical salvage surgery with combined 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) positron-emission tomography (PET)/computed tomography (CT) compared to conventional imaging. MATERIALS AND METHODS: A retrospective review was performed of all patients in a provincial database with recurrent gynaecological malignancies being considered for pelvic exenteration that underwent restaging with CT/PET between March 2011 and October 2014. Findings on PET and conventional imaging (CT±pelvic MRI) were abstracted. Disease sites were classified according to the location (regional nodal metastases, extra-regional nodal metastases, peritoneum, or other distant sites) and diagnostic certainty (definitive or equivocal). The proportion of patients positive for extra-regional recurrence was calculated for PET and conventional imaging. In addition, the proportion of patients with indeterminate lesions only was calculated for each modality and the sites of indeterminate findings were tabulated. RESULTS: There were 85 patients (median age, 50 years; range: 30-81 years) with carcinoma of cervix (n=51), endometrium (n=18), vagina (n=6), or vulva (n=10). Extra-regional recurrence was detected in 8/85 (9.4%) and 24/85 (28.2%) patients on conventional imaging and PET, respectively (p=0.0017). The greatest impact of PET compared to conventional imaging was in the detection of extra-regional nodal metastases. PET had significantly fewer examinations equivocal for extra-regional recurrence versus conventional imaging (6/85 [7.1%] and 38/85 [44.7%], respectively, p<0.001). CONCLUSION: In patients with recurrent gynaecological malignancies being considered for radical salvage surgery, PET may identify significantly more extra-regional recurrence than conventional imaging. PET may also result in fewer equivocal lesions. The impact of these results on patient management and outcome should be confirmed in future prospective trials.