Talc Pleurodesis With Intense 18F-FDG Activity But No 68Ga-DOTA-TATE Activity on PET/CT

Talc pleurodesis (TP) is a technique, widely employed in the management of patients with persistent pleural effusions or pneumothoraces not amenable to other treatment options. It is well documented, that talc deposits produce areas of highly increased 18F-FDG uptake, due to talc-induced inflammation. We present a case of a patient with history of TP who was evaluated with both 18F-FDG and 68Ga-DOTA-TATE. The hypermetabolic area seen on 18F-FDG-PET-CT in the region of talc placement, showed no uptake by 68Ga-DOTA-TATE, suggesting the potential role of 68Ga-DOTA-TATE-PET-CT in elucidating 18F-FDG-postitive lesions in patients with history of both neuroendocrine malignancy and TP

Utility of [18F]2-Fluoro-2-Deoxyglucose-PET in Sporadic and Tuberous Sclerosis-Associated Lymphangioleiomyomatosis

Mutations in tuberous sclerosis complex (TSC) genes are associated with dysregulated mammalian target of rapamycin (mTOR)/Akt signaling and unusual neoplasms called perivascular epithelioid cell tumors (PEComas), including angiomyolipomas (AMLs) and lymphangioleiomyomatosis (LAM). Tools that quantify metabolic activity and total body burden of AML and LAM cells would be valuable for the assessment of disease progression and the response to therapy in patients with TSC and LAM. Our hypothesis was that constitutive activation of mTOR in LAM and AML cells would result in increased glucose uptake of [18F]2-fluoro-2-deoxyglucose (FDG) on PET scanning, as has been suggested by a single prior case report. After institutional review board approval, FDG-PET scanning was performed in six LAM patients. Six additional LAM patients underwent FDG-PET scanning for clinical evaluation of suspected malignancy. Pleural uptake related to prior therapy was identified in four individuals with a remote history of talc pleurodesis. Focal increased uptake was observed in a supraclavicular lymph node in a patient with Hodgkin lymphoma and in a lung nodule in a patient with a biopsy-documented primary lung adenocarcinoma. In one TSC-LAM patient with a biopsy-documented malignant uterine PEComa, robust uptake was noted in metastatic nodules in the lung but not in the LAM-involved lung parenchyma or the patient's massive abdominal lymphangioleiomyomas. No abnormal uptake was identified in the AMLs or LAM lesions in any patients. This pilot study suggests that FDG-PET scans are negative in patients with benign PEComas and therefore are not likely to be useful for estimating the burden of disease in patients with TSC or LAM, but that FDG-PET scans can be used to identify or exclude other neoplasms in these patients