AUTHOR=Vehof Volker , Büther Florian , Florian Anca , Drakos Stefanos , Chamling Bishwas , Kies Peter , Stegger Lars , Yilmaz Ali 

TITLE=Hybrid CMR- and FDG-PET-Imaging Gives New Insights Into the Relationship of Myocardial Metabolic Activity and Fibrosis in Patients With Becker Muscular Dystrophy

JOURNAL=Frontiers in Cardiovascular Medicine

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/cardiovascular-medicine/articles/10.3389/fcvm.2022.793972

DOI=10.3389/fcvm.2022.793972

ISSN=2297-055X

ABSTRACT=Cardiac-involvement in Becker muscular dystrophy (BMD) patients is an important predictor of mortality. The cardiac-phenotype is characterized by slowly progressive myocardial-fibrosis starting in LV free-wall segments and extends into septal-wall during disease-course. The reason for this characteristic cardiac-phenotype is unknown and comprehensive approaches using hybrid imaging combining CMR with FDG-PET are limited. The present study comprises  function and fibrosis(LGE)-imaging by CMR and assessment of metabolism by FDG-PET applied 65 minutes after tracer injection. Uptake values from 60-65 minutes p.i. are divided by area under blood activity curve and reported as percentages relative to the segment with maximal myocardial FDG-uptake. A characteristic pattern of LGE in LV lateral-wall was observed in 13/14, an additional septal LGE-pattern in 6/14 patients, while one patient had no LGE at all. Segmental FDG-uptake was 88±6%(lateral-wall) vs. 77±10%(septal-wall);p<0.001. An inverse-relationship between segmental FDG-activity and segmental LGE extent (r=-0.33;p=0.09) was observed. There were six LGE-positive patients with segmental difference in FDG-uptake of >15% in LV lateral-wall compared to septal-wall (=∆FDG-high group, lateral-FDG=91±3% vs. septal-FDG=69±8%;p<0.001). The remaining seven LGE-positive patients showed a segmental difference in FDG-uptake of ≤15% (=∆FDG-low group, lateral-FDG=85±7% vs. septal-FDG=83±5%;p=0.37). While only minor differences in LGE extent were observed in ∆FDG-high group (LV lateral-wall vs. septal-wall;p=0.09), there were large differences in ∆FDG-low group (p<0.004). Presumably due to a higher workload, segmental myocardial metabolic activity is higher in LV free-wall of BMD patients as reflected by FDG-uptake - this however seems to be dependent on and limited by the extent of myocardial fibrosis revealed by LGE-imaging.