Simultaneous cardiac ^sup 18^F-FDG PET/MR for the assessment of different stages of cardiac impairment in patients with Anderson-Fabry disease

Background: Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with severe multi-organ dysfunction. While native myocardial T1 mapping by magnetic resonance (MR) may allow non-invasive measurement of myocyte sphingolipid accumulation both positron emission tomography (PET) and MR are able to identify different pathological patterns of disease progression. Aim: We investigated the potential relationship between T1 mapping and 18F-FDG PET by cardiac simultaneous PET/MR imaging in AFD female patients. Methods: 17 AFD female patients without cardiac symptoms and with normal left ventricular (LV) function underwent simultaneous cardiac PET/MR (Biograph mMR; Siemens Healthcare, Erlangen, Germany) imaging after administration of 18F-FDG and contrast agent injection (gadolinium-DPTA) for assessment of late gadolinium enhancement (LGE). In all patients and in 7 female controls T1 mapping was performed using native pre-contrast T1 Modified Look-Locker Inversion-recovery (MOLLI) prototype sequences. For the T1 mapping quantification, LV apical, mid-ventricular and basal short-axis slices were considered. Mean T1 values were measured by drawing a 6-pixel size region of interest in the septal and lateral segments of each slice. Cardiac FDG uptake was quantified by measuring the standardized uptake value in 17 myocardial segments in each subject. The coefficient of variation (COV, i.e. the standard deviation divided by the average) of the uptake of the 17 segments was calculated as an index of heterogeneity in the heart and values >0.17 were considered abnormal. Results: 5 patients showed focal LGE indicating intra-myocardial fibrosis and were excluded from the final analysis. Compared with controls, mean T1 values of AFD female patients were significantly lower (1238±51.1 vs. 1334.32±26.6, p