- Meeting abstract
- Open Access
2098 Magnetic resonance imaging at 3 Tesla to quantify regional myocardial blood flow after myocardial infarction: comparison with 13N-ammonia positron emission tomography and microspheres
© Schuleri et al; licensee BioMed Central Ltd. 2008
- Published: 22 October 2008
- Myocardial Blood Flow
- Post Myocardial Infarction
- Regional Myocardial Blood Flow
- Absolute Myocardial Blood Flow
- Patlak Plot
Cardiac MR perfusion imaging is emerging as a powerful clinical tool. However, PET is currently considered a noninvasive gold standard for quantification of myocardial blood flow (MBF). Direct validation of 3T-perfusion MRI after myocardial infarction (MI) has not been reported.
The purpose of this study was compare absolute MBF measurements from 3T-MRI, 13NH3-ammonia PET, and microsphere after MI.
MI was induced in 5 minipigs by a 120-min occlusion of the LAD followed by reperfusion. PET and 3T-MRI studies were performed on the same day 1 or 3 days post MI. Microspheres were injected directly after the MR perfusion acquisition. First pass contrast enhanced myocardial MR images were obtained at rest after a 0.05 mmol/kg BW Gd-injection with a FLASH sequence on a 3 Tesla magnet (TIM Trio, Siemens Medical Solutions). Myocardial perfusion (ml/min/g) was quantified from arterial input and myocardial output function by using a Patlak plot analysis. From dynamic 13N-ammonia PET studies, MBF was quantified by fitting to a validated 3-compartment model. Quantitative MBF measurements from 3T-MRI were compared to that of PET using a modified 17 segment AHA model. A total of 64 segments were evaluated. Post mortem the pig hearts were harvested and cut into 8 mm slices according to the short axis MRI prescription. Eight sectors per slice were used to compare matching microsphere flow measurements and MRI values.
Quantitative 3T-MRI MBF measurements showed a moderate correlation with percent uptake of ammonia (R = 0.44; p < 0.0001), and PET-derived absolute MBF(R = 0.46; p < 0.0001) (Figure 1C). Bland-Altman Analysis of PET and MRI absolute MBF demonstrated a mean difference -0.07 ml/min/g with confidence limits of 0.59 and 0.73 ml/min/g for PET and MRI, respectively. Quantitative 3T-MRI MBF measurements showed a better correlation with radioactive microsphere measurements (R = 0.54; p = 0.004).
Quantitative two-compartment analysis of myocardial perfusion MRI using a Patlak plot approach provides an accurate assessment of absolute regional MBF at rest post MI. Further evaluation over a wider range of flow, including high stress flow is warranted.
This article is published under license to BioMed Central Ltd.