Imaging of Tumor Hypoxia With 18F-EF5 PET/MRI in Cervical Cancer.

PURPOSE OF THE REPORT: The aim of this study was to evaluate the distribution of hypoxia using 18F-EF5 as a hypoxia tracer in cervical cancer patients with PET/MRI. We investigated the association between this 18F-EF5-PET tracer and the immunohistochemical expression of endogenous hypoxia markers: HIF1α, CAIX, and GLUT1. PATIENTS AND METHODS: Nine patients with biopsy-proven primary squamous cell cervix carcinoma (FIGO 2018 radiological stages IB1-IIIC2r) were imaged with dual tracers 18F-EF5 and 18F-FDG using PET/MRI (Int J Gynaecol Obstet. 2019;145:129-135). 18F-EF5 images were analyzed by calculating the tumor-to-muscle ratio to determine the hypoxic tissue (T/M ratio >1.5) and further hypoxic subvolume (HSV) and percentage hypoxic area. These 18F-EF5 hypoxic parameters were correlated with the size and localization of tumors in 18F-FDG PET/MRI and the results of hypoxia immunohistochemistry. RESULTS: All primary tumors were clearly 18F-FDG and 18F-EF5 PET positive and heterogeneously hypoxic with multiple 18F-EF5-avid areas in locally advanced cancer and single areas in clinically stage I tumors. The location of hypoxia was detected mainly in the periphery of tumor. Hypoxia parameters 18F-EF5 max T/M ratio and HSV in primary tumors correlated independently with the advanced stage (P = 0.036 and P = 0.040, respectively), and HSV correlated with the tumor size (P = 0.027). The location of hypoxia in 18F-EF5 imaging was confirmed with a higher hypoxic marker expression HIF1α and CAIX in tumor fresh biopsies. CONCLUSIONS: The 18F-EF5 imaging has promising potential in detecting areas of tumor hypoxia in cervical cancer.

Iron overload in allogeneic hematopoietic cell transplantation outcome: a meta-analysis.

An elevated ferritin level before allogeneic hematopoietic cell transplantation (HCT) is an adverse prognostic factor for overall survival (OS) and nonrelapse mortality. Because ferritin is an imperfect surrogate of iron stores, the prognostic role of iron overload remains unclear. We conducted a patient-level meta-analysis of 4 studies that used magnetic resonance imaging to estimate pre-HCT liver iron content (LIC). An elevated LIC was not associated with a significant increase in mortality: the hazard ratio (HR) for mortality associated with LIC > 7 mg/g dry weight (primary endpoint) was 1.4 (P = .18). In contrast, ferritin >1000 ng/mL was a significant prognostic factor (HR for mortality, 1.7; P = .036). There was, however, no significant association between ferritin > 2500 and mortality. This meta-analysis suggests that iron overload, as assessed by LIC, is not a strong prognostic factor for OS in a general adult HCT population. Our data also suggest that ferritin is an inadequate surrogate for iron overload in HCT.

Prognostic impact of pretransplant iron overload measured with magnetic resonance imaging on severe infections in allogeneic stem cell transplantation.

OBJECTIVE: Infections and graft-versus-host disease (GVHD) are the main causes of transplant-related mortality (TRM) of patients undergoing allo-SCT. The role of iron overload (IO) has been debated in this context. Studies, performed with non-specific surrogate markers of iron, suggest that IO predicts poor outcome after allo-SCT. METHODS: In this prospective study, we quantified pretransplant IO with MRI-based hepatic iron concentration (HIC) measurement; the degree of IO was used to predict infections, GVHD, and mortality after allo-SCT. Logistic univariate, multivariate, and Cox's regression analyses were performed. RESULTS: Iron overload was present in 78% of the patients (HIC>36 µmol/g). The median HIC was 98 µmol/g (range 5-348). There were no cases of cardiac iron excess. IO was significantly associated with severe infections during the early post-transplant period (for every 10 µmol/g increase OR: 1.15, 95% CI 1.05-1.26, P = 0.003). The odds for severe infections increased 6.5- (>125 µmol/g OR: 6.5, P = 0.013) to 14-fold (>269 µmol/g OR: 14.1, P = 0.040) with increasing HIC. IO was found to be associated with reduced risk of acute and chronic GVHD. Although TRM was due to infection-related deaths, IO was not associated with TRM or OS. CONCLUSION: Pretransplant IO, measured with a direct MRI-based measurement, predicts severe infections in the early post-transplant period.

Quantitative liver iron measurement by magnetic resonance imaging: in vitro and in vivo assessment of the liver to muscle signal intensity and the R2* methods.

PURPOSE: To evaluate the liver-to-muscle signal intensity and R2* methods to gain a transferable, clinical application for liver iron measurement. MATERIALS AND METHODS: Sixteen liver phantoms and 33 human subjects were examined using three 1.5-T MRI scanners from two different vendors. Phantom-to-muscle and liver-to-muscle signal intensity ratios were analyzed to determine MRI estimated phantom and hepatic iron concentration (M-PIC and M-HIC, respectively). R2* was calculated for the phantoms and the liver of human subjects. Seven patients' biochemical hepatic iron concentration was obtained. RESULTS: M-PIC and R2* results of three scanners correlated linearly to phantom iron concentrations (r=0.984 to 0.989 and r=0.972 to 0.981, respectively), and no significant difference between the scanners was found (P=.482 and P=.846, respectively) in vitro. The patients' R2* correlated linearly to M-HIC of the standard scanner (r=0.981). M-HIC values did not differ from those obtained from the biopsy specimens (P=.230). The difference in M-HIC was significant, but the difference in R2* was not significant between the scanners (P<.0001 and P=.505, respectively) in vivo. CONCLUSION: Both methods, M-HIC and R2*, are reliable iron concentration indicators with linear dependence on iron concentration in vivo and in vitro. The R2* method was found to be comparable among different scanners. Transferability testing is needed for the use of the methods at various scanners.