ABSTRACT
PURPOSE: Long axial field-of-view (LAFOV) PET/CT systems enable PET/CT scans with reduced injected activities because of improved sensitivity. With this study, we aimed to examine the foetal radiation dose from an 18F-FDG PET/CT scan on a LAFOV PET/CT system with reduced injected activity. METHODS: Two pregnant women were retrospectively included and received an 18F-FDG PET/CT scan on a LAFOV PET/CT system with an intravenous bolus injection of 0.30 MBq/kg. Foetal radiation exposure from the PET was estimated using dose conversion factors from three published papers. Radiation exposure from the CT scans was estimated using CT-Expo. RESULTS: Foetal radiation dose from the PET scan ranged between 0.11 and 0.44 mGy. Foetal radiation exposure from the CT scan ranged between < 0.10 - 0.90 mGy depending if the foetus was included in the field-of-view. CONCLUSION: Foetal radiation dose could be reduced to < 1.5 mGy when scanning pregnant patients on a LAFOV PET/CT system. The radiation dose to the foetus was reduced significantly in our study due to the increased sensitivity of the LAFOV PET/CT system.
ABSTRACT
Direct oral anticoagulants (DOACs) are increasingly prescribed in treatment of cancer-associated thrombosis, but limited data exist regarding safety of DOACs in patients with brain metastases. We aimed to determine the incidence of intracranial hemorrhage (ICH) in patients with brain metastases receiving DOACs or low-molecular-weight heparin (LMWH) for venous thromboembolism or atrial fibrillation. An international 2-center retrospective cohort study was designed. Follow-up started on the first day of concomitant anticoagulation and brain tumor diagnosis. At least 2 brain imaging studies were mandated. The primary outcome was the cumulative incidence of any spontaneous ICH at 12-month follow-up with death as a competing risk. Major ICH was defined as spontaneous, ≥10 mL in volume, symptomatic, or requiring surgical intervention. Imaging studies were centrally reviewed by a neuroradiologist blinded for anticoagulant type. PANWARDS (platelets, albumin, no congestive heart failure, warfarin, age, race, diastolic blood pressure, stroke) score for prediction of ICH was calculated. We included 96 patients with brain metastases (41 DOAC, 55 LMWH). The 12-month cumulative incidence of major ICH was 5.1% in DOAC-treated patients and 11.1% in those treated with LMWH (hazard ratio [HR], 0.45; 95% confidence interval [CI], 0.09-2.21). When anticoagulation was analyzed as a time-varying covariate, the risk of any ICH did not differ between DOAC- and LMWH-treated patients (HR, 0.98; 95% CI, 0.28-3.40). PANWARDS score was not associated with ICH risk. This international 2-center study suggests comparable safety of LMWH and DOACs in patients with brain metastases.
