Cardiovascular magnetic resonance by non contrast T1-mapping allows assessment of severity of injury in acute myocardial infarction

Abstract

BackgroundCurrent cardiovascular magnetic resonance (CMR) methods, such as late gadolinium enhancement (LGE) and oedema imaging (T2W) used to depict myocardial ischemia, have limitations. Novel quantitative T1-mapping techniques have the potential to further characterize the components of ischemic injury. In patients with myocardial infarction (MI) we sought to investigate whether state-of the art pre-contrast T1-mapping (1) detects acute myocardial injury, (2) allows for quantification of the severity of damage when compared to standard techniques such as LGE and T2W, and (3) has the ability to predict long term functional recovery.Methods3T CMR including T2W, T1-mapping and LGE was performed in 41 patients [of these, 78% were ST elevation MI (STEMI)] with acute MI at 12-48 hour after chest pain onset and at 6 months (6M). Patients with STEMI underwent primary PCI prior to CMR. Assessment of acute regional wall motion abnormalities, acute segmental damaged fraction by T2W and LGE and mean segmental T1 values was performed on matching short axis slices. LGE and improvement in regional wall motion at 6M were also obtained.ResultsWe found that the variability of T1 measurements was significantly lower compared to T2W and that, while the diagnostic performance of acute T1-mapping for detecting myocardial injury was at least as good as that of T2W-CMR in STEMI patients, it was superior to T2W imaging in NSTEMI. There was a significant relationship between the segmental damaged fraction assessed by either by LGE or T2W, and mean segmental T1 values (P < 0.01). The index of salvaged myocardium derived by acute T1-mapping and 6M LGE was not different to the one derived from T2W (P = 0.88). Furthermore, the likelihood of improvement of segmental function at 6M decreased progressively as acute T1 values increased (P < 0.0004).ConclusionsIn acute MI, pre-contrast T1-mapping allows assessment of the extent of myocardial damage. T1-mapping might become an important complementary technique to LGE and T2W for identification of reversible myocardial injury and prediction of functional recovery in acute MI.

Alterations in Cardiac Deformation, Timing of Contraction and Relaxation, and Early Myocardial Fibrosis Accompany the Apparent Recovery of Acute Stress-Induced (Takotsubo) Cardiomyopathy: An End to the Concept of Transience

“…The increased LV mass 24 is presumably a reflection of the significant myocardial edema seen in the myocardium during the acute stage, previously reported by us and others 7,21,25 . There is extensive evidence that pre-contrast T1 mapping is reflective of edema, previously provided from our group 26 and by others [27][28][29] . Here we replicate our previous findings 7 showing that LV edema subsides in the previously well contracting segments.…”

Cardiac Magnetic Resonance and Myocardial Viability: Why Is It so Important?

“…45 There are several studies that showed that T1-mapping is useful in identifying more diffuse forms of fibrosis in the remote myocardium and the peri-infarct area (the acquisition time is faster and the spatial resolution is better). 46,47 The notion of peri-infarct zone ("gray zone") was introduced by Schmidt et al The quantification of the peri-infarcted zone can be made by tracing the endo-and epicardial margins in the short-axis sequence and the hypersignal region. 41 The infarct nucleus is defined as the region from the myocardium with a signal intensity higher than 50%.…”

T 1 mapping for assessment of myocardial injury and microvascular obstruction at one week post myocardial infarction

“…LGE+ segments were used as the oedema-positive test state, as previously described, [3] and normal segments from healthy volunteers were used as the oedemanegative test state. All T1 map and T2W-SPAIR segments were categorised as LGE+ or LGE-, and were only included if they were artefact-free in both T1 maps and T2W-SPAIR images.…”

“…Quantitative T1 mapping has recently emerged as a powerful tool for myocardial tissue characterisation, [1] and previous work has already illustrated its utility for delineating myocardial oedema in acute myocardial infarction (AMI), [2,3] and acute stress-induced cardiomyopathy patients. [4,5] We have seen that, in the first 24 hours after acute myocardial injury, native T1 mapping assessment of oedema appears to be at least as good as that of T2-weighted (T2W) short tau inversion recovery imaging, [3] which is the current standard for oedema assessment with cardiovascular magnetic resonance (CMR).…”

“…[4,5] We have seen that, in the first 24 hours after acute myocardial injury, native T1 mapping assessment of oedema appears to be at least as good as that of T2-weighted (T2W) short tau inversion recovery imaging, [3] which is the current standard for oedema assessment with cardiovascular magnetic resonance (CMR). However, it is still unknown whether T1 mapping's strengths are maintained beyond 24 hours after AMI, asdespite promising initial studies with T1-weighted imaging at 1.5T-it has not yet been studied at this time point.…”