Native T1-mapping using cardiovascular magnetic resonance detects myocardium at risk during the first week following myocardial infarction in a swine model and in patients - comparison to contrast-enhanced cine steady-state free precession
摘要
Myocardium at risk (MaR) can be evaluated by cardiovascular magnetic resonance (CMR) imaging using contrast-enhanced steady state free precession (CE-SSFP) in patients after ST-elevation myocardial infarction (STEMI). However, CE-SSFP utilizes gadolinium contrast, which is contraindicated in patients with severe renal insufficiency. Native T1-mapping is a non-contrast CMR method which has been shown feasible in assessing MaR, enabling patients with gadolinium contrast contraindications to be examined. However, native T1-mapping data have been presented in the sub-acute phase suggesting to also depict infarct size (IS), as assessed by late gadolinium enhancement (LGE). Therefore, it is unclear whether native T1-mapping depicts MaR or IS during the first week after reperfusion. We hypothesized that native T1-mapping agrees with MaR as assessed by CE-SSFP and overestimates IS as assessed by LGE in an experimental pig model and in patients during the first week after STEMI.
MethodsA retrospective analysis was performed using CMR images from an infarct/reperfusion experimental pig model. CMR imaging was performed at 2 h, 24 h and 7 days after reperfusion in a serially imaged group (n = 7) and at 4 days in a single-timepoint imaged group (n = 4). Also, STEMI patients with a single vessel LAD occlusion (n = 11) were CMR imaged between 3 to 7 days after reperfusion. Native T1-mapping MOLLI, CE-SSFP and LGE were acquired for each scan in both animals and patients. In animals, images with an additional T1-mapping sequence, SASHA, were acquired. Enhanced areas on T1-maps, CE-SSFP and LGE images were quantified and compared.
ResultsIn pigs, native T1-mapping MOLLI agreed with CE-SSFP in the single-timepoint- and serially imaged groups (bias: 0.3 ± 6.6% (mean ± 2SD), and 0.9 ± 18%), respectively. Native T1-mapping SASHA also agreed with CE-SSFP in the serially imaged group (bias: -0.1 ± 18%). However, MOLLI overestimated IS by LGE in pigs in the serially- and single-timepoint imaged groups (bias: 21 ± 26%, and 18 ± 17%), respectively. Similar results were seen in patients (MOLLI vs. CE-SSFP: 0.8 ± 7.5%, and MOLLI vs. LGE: 31 ± 22%).
ConclusionOur findings suggest that native T1-mapping agrees with CE-SSFP during the first week after myocardial infarction when evaluating MaR. Also, native T1-mapping overestimates the LGE hyperintense area, indicating that native T1-mapping does not primarily depict infarct size.