Native T<sub>1</sub> mapping for characterization of acute and chronic myocardial infarction in swine: Comparison with contrast‐enhanced MRI

Xi, Liu; Hou, Jianglong; Yang, Zhi-Gang; Xia, Chunchao; Xie, Linjun; Ye, Pengfei; Peng, Wanlin; Li, Lei; Yang, Manshu; Guo, Yingkun

doi:10.1002/jmri.26043

Cited by 3 publications

(5 citation statements)

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“…We note that, while our resting T1 values are in line with those from other studies done on a 3 T system, 26,62 our changes in T1 from rest to stress (1.3% at the 4× adenosine dose, Table 1) are lower than what others have reported (2.8‐6.2%) 26,29,49 . Similarly, when using a conversion factor derived from Nickander et al, where a 34.4% change in MBV corresponded to a 6.2% change in T1, 29 our measured T1 values equate to an MBV increase of 7.31% at the 4× adenosine dose (Table 6), whereas other studies using systemic adenosine infusion reported increases of 30‐34% 29,52 .…”

Section: Discussionsupporting

confidence: 90%

“…Both our T1 and T2 values were similar to those reported by other groups using a 3 T system 26,50,62 . While we did not make reproducibility measurements in this study, T1 and T2 measures as made by our group have been shown to be reproducible 33,37,66–69 : rest T1 values were in the range 1148‐1230 ± 45.97 with a coefficient of variation (CV) of 0.038, and rest T2 values in the range 36.5‐39.8 ± 1.38 with a CV of 0.036.…”

Section: Discussionsupporting

confidence: 87%

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Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2

et al. 2021

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Stress imaging identifies ischemic myocardium by comparing hemodynamics during rest and hyperemic stress. Hyperemia affects multiple hemodynamic parameters in myocardium, including myocardial blood flow (MBF), myocardial blood volume (MBV), and venous blood oxygen levels (PvO2). Cardiac T2 is sensitive to these changes and therefore is a promising non‐contrast option for stress imaging; however, the impact of individual hemodynamic factors on T2 is poorly understood, making the connection from altered T2 to changes within the tissue difficult. To better understand this interplay, we performed T2 mapping and measured various hemodynamic factors independently in healthy pigs at multiple levels of hyperemic stress, induced by different doses of adenosine (0.14‐0.56 mg/kg/min). T1 mapping quantified changes in MBV. MBF was assessed with microspheres, and oxygen consumption was determined by the rate pressure product (RPP). Simulations were also run to better characterize individual contributions to T2. Myocardial T2, MBF, oxygen consumption, and MBV all changed to varying extents between each level of adenosine stress (T2 = 37.6‐41.8 ms; MBF = 0.48‐1.32 mL/min/g; RPP = 6507‐4001 bmp*mmHg; maximum percent change in MBV = 1.31%). Multivariable analyses revealed MBF as the dominant influence on T2 during hyperemia (significant β‐values >7). Myocardial oxygen consumption had almost no effect on T2 (β‐values <0.002); since PvO2 is influenced by both oxygen consumption and MBF, PvO2 changes detected by T2 during adenosine stress can be attributed to MBF. Simulations varying PvO2 and MBV confirmed that PvO2 had the strongest influence on T2, but MBV became important at high PvO2. Together, these data suggest a model where, during adenosine stress, myocardial T2 responds predominantly to changes in MBF, but at high hyperemia MBV is also influential. Thus, changes in adenosine stress T2 can now be interpreted in terms of the physiological changes that led to it, enabling T2 mapping to become a viable non‐contrast option to detect ischemic myocardial tissue.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionsupporting

confidence: 87%

Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2

et al. 2021

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“…14,15 The performance of native T 1 mapping on characterizing MI has also been validated in animal models. [16][17][18] The heightened native T 1 values of MI observed in those studies have been ascribed to increased extracellular volume (ECV) fractions resulting from the edematous and fibrotic myocardium 19 and enhanced water proton diffusion. 20,21 Besides native T 1 , water-macromolecular proton magnetization transfer (MT) has long been used to enhance contrast between normal and infarcted tissue 22,23 and between blood and healthy myocardium [24][25][26] using off-resonance MT preparation pulses.…”

Section: Introductionmentioning

confidence: 96%

“…Recently, there is emerging data that native T 1 mapping at 3T provides significantly greater sensitivity and specificity for chronic MI over native T 1 mapping at 1.5T and can reliably determine the location, size, and transmurality of chronic MI . The performance of native T 1 mapping on characterizing MI has also been validated in animal models . The heightened native T 1 values of MI observed in those studies have been ascribed to increased extracellular volume (ECV) fractions resulting from the edematous and fibrotic myocardium and enhanced water proton diffusion …”

Section: Introductionmentioning

confidence: 99%

Non‐contrast myocardial infarct scar assessment using a hybrid native T₁ and magnetization transfer imaging sequence at 1.5T

Duan

Zhu

Jang

et al. 2018

Magnetic Resonance in Med

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Purpose To develop a gadolinium‐free cardiac MR technique that simultaneously exploits native T1 and magnetization transfer (MT) contrast for the imaging of myocardial infarction. Methods A novel hybrid T one and magnetization transfer (HYTOM) method was developed based on the modified look‐locker inversion recovery (MOLLI) sequence, with a train of MT‐prep pulses placed before the balanced SSFP (bSSFP) readout pulses. Numerical simulations, based on Bloch‐McConnell equations, were performed to investigate the effects of MT induced by (1) the bSSFP readout pulses, and (2) the MT‐prep pulses, on the measured, “apparent,” native T1 values. The HYTOM method was then tested on 8 healthy adult subjects, 6 patients, and a swine with prior myocardial infarction (MI). The resulting imaging contrast between normal myocardium and infarcted tissues was compared with that of MOLLI. Late gadolinium enhancement (LGE) images were also obtained for infarct assessment in patients and swine. Results Numerical simulation and in vivo studies in healthy volunteers demonstrated that MT effects, resulting from on‐resonance bSSFP excitation pulses and off‐resonance MT‐prep pulses, reduce the measured T1 in both MOLLI and HTYOM. In vivo studies in patients and swine showed that the HYTOM sequence can identify locations of MI, as seen on LGE. Furthermore, the HYTOM method yields higher myocardium‐to‐scar contrast than MOLLI (contrast‐to‐noise ratio: 7.33 ± 1.67 vs. 3.77 ± 0.66, P < 0.01). Conclusion The proposed HYTOM method simultaneously exploits native T1 and MT contrast and significantly boosts the imaging contrast for myocardial infarction.

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“…Due to the concern for contrast induced nephrogenic systemic fibrosis in patients with kidney dysfunction, the use of native non-contrast mapping with T1 weighted imaging has been studied in which the T1 relaxation times are measured to look for myocardial edema and fibrosis. It was shown recently by Liu et al [2017] that native T1 images are good at picking up both acute myocardial infarct and chronic myocardial infarct areas, however, they cannot differentiate between the two (33). However, this study presents another method for imaging in patients who cannot undergo other modalities to find the site of infarct.…”

Section: The Role Of Mrimentioning

confidence: 99%

Incidence and predictors of acute coronary syndrome within a year following a negative stress test—a false sense of security: is routine screening any useful?

et al. 2018

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One of the major issues in management of the acute coronary syndrome (ACS) is classification of patients with atypical presentation who have low risk of having a coronary episode at presentation. There have been multiple studies on the stratification of high risk patients and medical management of such cases, however, there is a sub-class of patients who do not fit any category. In this paper, we have looked at the current literature on stratification of patients based on the study tools available and the risk of having a coronary episode during the following year. In our overview, we have found that the current methods in place namely, cardiac stress test and stress echocardiogram have a good prognostic factor in terms of mortality in the next one year and can safely stratify the patients at low risk when correlated with clinical presentation and laboratory studies. However, such data are limited for computerized tomography or magnetic resonant imaging and their application might be limited due to accessibility and cost of studies. Current guidelines for classification of high risk patient do an excellent job and we believe that proper application of stress tests together with other imaging modalities together with laboratory, clinical judgment, and proper use of medical management can help with safe discharge of patients from the emergency department (ED) and reduction of burden from healthcare.

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Native T₁ mapping for characterization of acute and chronic myocardial infarction in swine: Comparison with contrast‐enhanced MRI

Cited by 3 publications

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Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2

Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2

Non‐contrast myocardial infarct scar assessment using a hybrid native T₁ and magnetization transfer imaging sequence at 1.5T

Incidence and predictors of acute coronary syndrome within a year following a negative stress test—a false sense of security: is routine screening any useful?

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Native T1 mapping for characterization of acute and chronic myocardial infarction in swine: Comparison with contrast‐enhanced MRI

Cited by 3 publications

References 0 publications

Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2

Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2

Non‐contrast myocardial infarct scar assessment using a hybrid native T1 and magnetization transfer imaging sequence at 1.5T

Incidence and predictors of acute coronary syndrome within a year following a negative stress test—a false sense of security: is routine screening any useful?

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Product

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Native T₁ mapping for characterization of acute and chronic myocardial infarction in swine: Comparison with contrast‐enhanced MRI

Non‐contrast myocardial infarct scar assessment using a hybrid native T₁ and magnetization transfer imaging sequence at 1.5T