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10 Manganese-enhanced T1 mapping in myocardial infarction: validation with 18F-FDG PET/MR
  1. Nick B Spath1,
  2. Adriana Tavares1,2,
  3. Gillian A Gray1,
  4. Marc R Dweck1,3,
  5. David E Newby1,3,4,
  6. Phillip C Yang5,
  7. Maurtis A Jansen1,2,
  8. Scott I Semple4
  1. 1BHF/University Centre for Cardiovascular Science, University of Edinburgh, UK
  2. 2Edinburgh Preclinical Imaging, University of Edinburgh, UK
  3. 3Department of Cardiology, Royal Infirmary of Edinburgh, UK
  4. 4Clinical Research Imaging Centre, University of Edinburgh, UK
  5. 5Department of Cardiology, Stanford University, Stanford, CA, USA


Introduction Manganese-enhanced magnetic resonance imaging (MEMRI) is a promising non-invasive imaging tool in viability and cardiomyopathy, quantifying infarct size more accurately than late-gadolinium enhancement, as we previously demonstrated. We aimed to validate MEMRI viability against 18F-FDG positron emission tomography (PET).

Methods Sprague-Dawley rats (male; 180–300 g) underwent permanent surgical anterior myocardial infarction (n=11), or sham surgery (n=2), with dual MEMRI and 18F-FDG PET assessment at 12 weeks. MEMRI (7 T spectrometer, Agilent, UK) was achieved with intravenous manganese gluconate (EVP1001–1, Eagle-Vision-Pharmaceuticals, USA; n=6, 22 μmol/kg) and mangafodipir (Teslascan, IC-Targets, Norway; n=7, 44 μmol/kg). Anatomical and functional imaging preceded cardiac-gated Modified Look-Locker Inversion recovery (MoLLI) before and 20 min post-contrast (at maximal infarct slice). Commercially available software generated standardised T1 maps for ROI-contouring. For PET imaging, intravenous 18F-FDG (20–30 MBq) was administered with PET data acquired for 60 min, followed by cardiac-gated acquisition (10 min). PET/MR images were co-registered and fused for analysis.

Results Infarct size assessed by MEMRI T1 mapping was smaller than by native T1 at 12 weeks (mean 23.34 vs 18.68%; p=0.001). Native T1 mapping consistently overestimated infarct size (bias 25.76; 95% CI: 7.51 to 44.01; p=0.031) but there was excellent agreement between MEMRI T1 mapping and 18F-FDG (bias 1.30; 95% CI: −24.98 to 25.57; p=0.7). Post-MEMRI T1 values showed negative trend with increasing SUV (r2=0.25, p=0.08) whereas native T1 demonstrated no relationship (r2=0.0001, p>0.9).

Conclusion MEMRI T1 mapping identifies viable myocardium as well as 18F-FDG PET and was superior to native T1 mapping. Post-MEMRI T1 appears related to SUV where native T1 does not. This validation data informs the clinical translation of cardiac MEMRI.

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