Hybrid positron emission tomography-magnetic resonance imaging for assessing different stages of cardiac impairment in patients with Anderson-Fabry disease: AFFINITY study group.

AIMS: Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with multi-organ dysfunction. While native myocardial T1 mapping by magnetic resonance (MR) allow non-invasive measurement of myocyte sphingolipid accumulation, 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) and MR are able to identify different pathological patterns of disease progression. We investigated the relationship between T1 mapping and 18F-FDG uptake by hybrid PET-MR cardiac imaging in AFD female patients. METHODS AND RESULTS: Twenty AFD females without cardiac symptoms underwent cardiac PET-MR using 18F-FDG for glucose uptake. In all patients and in seven age- and sex-matched control subjects, T1 mapping was performed using native T1 Modified Look-Locker Inversion-recovery prototype sequences. 18F-FDG myocardial uptake was quantified by measuring the coefficient of variation (COV) of the standardized uptake value using a 17-segment model. T1 values of AFD patients were lower compared with control subjects (1236 ± 49 ms vs. 1334 ± 27 ms, P < 0.0001). Focal 18F-FDG uptake with COV >0.17 was detected in seven patients. COV was 0.32 ± 0.1 in patients with focal 18F-FDG uptake and 0.12 ± 0.04 in those without (P < 0.001). Patients with COV >0.17 had higher T1 values of lateral segments of the mid ventricular wall, compared with those with COV ≤0.17 (1216 ± 22 ms vs. 1160 ± 59 ms, P < 0.05). CONCLUSION: In females with AFD, focal 18F-FDG uptake with a trend towards a pseudo-normalization of abnormal T1 mapping values, may represent an intermediate stage before the development of myocardial fibrosis. These findings suggest a potential relationship between progressive myocyte sphingolipid accumulation and inflammation.

First experience of simultaneous PET/MRI for the early detection of cardiac involvement in patients with Anderson-Fabry disease.

PURPOSE: Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder associated with severe multiorgan dysfunction and premature death. Early diagnosis and treatment strategies play a key role in patient outcome. We investigated the potential role of hybrid PET/MR imaging in the assessment of early cardiac involvement in AFD patients. METHODS: Thirteen AFD patients without cardiac symptoms and with normal left ventricular function underwent simultaneous cardiac PET/MR imaging after administration of (18)F-FDG. 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. RESULTS: Six patients exhibited focal late gadolinium enhancement (LGE) indicating intramyocardial fibrosis, and four of these also had positive short inversion time inversion recovery (STIR) sequences. All patients with LGE and positive STIR MR images showed focal FDG uptake in the corresponding myocardial segments indicating inflammation. Of the seven patients with negative LGE and STIR images, five showed homogeneous FDG cardiac uptake and two showed heterogeneous FDG uptake. The COV was significantly greater in patients with focal FDG uptake (0.25 ± 0.02) than in those without (0.14 ± 0.07, p < 0.01). CONCLUSION: PET/MR imaging is clinically feasible for the early detection of cardiac involvement in patients with AFD. Further studies evaluating the role of hybrid PET/MR imaging in management of the disease in larger patient populations are warranted.