IJCS | Volume 32, Nº1, January/ February 2019

72 Figure 1 – “Images illustrating different combinations of FDG uptake and LGE transmurality. First column: FDG ≥ 50%/LGE non- transmural (‘PET viable/MRI viable); second column: FDG < 50%/LGE transmural (‘PET non-viable/MRI non-viable’); third column: FDG < 50%/LGE non-transmural (‘PET non-viable/MRI viable’). White arrows indicate the respective area of ischaemically affected myocardium.” – With permission from Rischpler et al, Eur Heart J Cardiovasc Imaging. 30 Erthal et al. Myocardial viability: from PARR-2 to IMAGE HF - current evidence and future directions Int J Cardiovasc Sci. 2019;32(1)70-83 Review Article assessment at 6 months. 30 The study has concluded that simultaneous assessment of glucose metabolismand scar assessment using a hybrid PET/MRI scanner is feasible. Moreover, the agreement between the techniques was high (82% of the segments were either non-viable or viable for both PET andMRI, k = 0.65). In only 18% of the segments was there disagreement, and, in all of them, PET suggested non-viability while MRI suggested viability. 30 The recovery was higher in the segments in which there was agreement between the techniques (78% versus 41% for PET viable/MRI viable and PET non-viable/MRI viable, respectively). Recovery was similar between PET non-viable/MRI viable and PET non-viable/MRI non- viable segments, suggesting PET better dichotomized the degree of recovery between viable and non-viable myocardium. In the PETnon-viable/MRI viable segments, there was some recovery (41%), suggesting a lower threshold for % FDG uptake cutoff (40-45% instead of 50%) may have detected some viable segments identified by MRI. Overall the techniques appear complementary. Their combined use as PET/MRmay offer comprehensive tissue characterization of metabolism, scar and function and may refine our ability to define viable myocardium. Further studies are warranted (Figures 1 and 2). 30 Clinical relevance of viability assessment: PARR-2 and STICH Several non-randomized studies have reported data that suggest a benefit of viability imaging in patients