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Assessment of myocardial infarction in mice by late gadolinium enhancement MR imaging using an inversion recovery pulse sequence at 9.4T.

Chapon C, Herlihy AH, Bhakoo KK - J Cardiovasc Magn Reson (2008)

Bottom Line: Contrast-to-noise (CNR) and signal-to-noise ratio (SNR) were measured and compared for each myocardial region of interest (ROI).The optimal TI, which corresponded to a minimum SNR in the normal myocardium, was 268 ms +/- 27.3.The SNR in the viable myocardium was significantly different from that found in the infarcted myocardium (17.2 +/- 2.4 vs 82.1 +/- 10.8; p = 0.006) leading to a maximal relative SI (Signal Intensity) between those two areas (344.9 +/- 60.4).

View Article: PubMed Central - HTML - PubMed

Affiliation: Stem Cell Imaging, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, UK. catherine.chapon@univ-angers.fr

ABSTRACT

Purpose: To demonstrate the feasibility of using an inversion recovery pulse sequence and to define the optimal inversion time (TI) to assess myocardial infarction in mice by late gadolinium enhancement (LGE) MRI at 9.4T, and to obtain the maximal contrast between the infarcted and the viable myocardium.

Methods: MRI was performed at 9.4T in mice, two days after induction of myocardial infarction (n = 4). For cardiovascular MR imaging, a segmented magnetization-prepared fast low angle shot (MP-FLASH) sequence was used with varied TIs ranging from 40 to 420 ms following administration of gadolinium-DTPA at 0.6 mmol/kg. Contrast-to-noise (CNR) and signal-to-noise ratio (SNR) were measured and compared for each myocardial region of interest (ROI).

Results: The optimal TI, which corresponded to a minimum SNR in the normal myocardium, was 268 ms +/- 27.3. The SNR in the viable myocardium was significantly different from that found in the infarcted myocardium (17.2 +/- 2.4 vs 82.1 +/- 10.8; p = 0.006) leading to a maximal relative SI (Signal Intensity) between those two areas (344.9 +/- 60.4).

Conclusion: Despite the rapid heart rate in mice, our study demonstrates that LGE MRI can be performed at 9.4T using a protocol similar to the one used for clinical MR diagnosis of myocardial infarction.

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Mean relative SI (%) (± SEM) of infarcted compared with viable myocardium at varying TIs.
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Figure 4: Mean relative SI (%) (± SEM) of infarcted compared with viable myocardium at varying TIs.

Mentions: Transmural myocardial infarction was confirmed in all mice using TTC staining (Figure 2). The TI0 was defined as the TI value, which s the SI of the non-infarcted (viable) myocardium. This value was unique for each mouse and ranged from 220 to 300 msec (Figure 3). The SNR in the viable myocardium was at its minimum (17.2 ± 2.4, ranging from 12.8 to 23.1) for a mean TI of 268 msec ± 27.3 corresponding to the optimal TI (referred to as TI0). Mean SNR, CNR and relative SI at TI0 are reported in Table 1. The minimum SNR, at TI0, in the viable myocardium (17.2 ± 2.4) was significantly different from that found in the infarcted myocardium (82.1 ± 10.8; p = 0.006) but not from the SNR in the blood (48.7 ± 16.6, p = 0.126). The mean CNR of infarcted tissue compared with viable myocardium was 76.6 ± 19.8, whereas infarcted tissue compared with blood was 25.7 ± 14.7, and blood compared with viable myocardium was 40.6 ± 21.2. The mean maximum relative SI of the infarcted tissue compared with viable myocardium was 344.9 ± 60.4% (Figure 4), and occurred at TI0 when SI of the viable myocardium was minimum, leading to an optimal CNR between viable and infarcted myocardial areas.


Assessment of myocardial infarction in mice by late gadolinium enhancement MR imaging using an inversion recovery pulse sequence at 9.4T.

Chapon C, Herlihy AH, Bhakoo KK - J Cardiovasc Magn Reson (2008)

Mean relative SI (%) (± SEM) of infarcted compared with viable myocardium at varying TIs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2244610&req=5

Figure 4: Mean relative SI (%) (± SEM) of infarcted compared with viable myocardium at varying TIs.
Mentions: Transmural myocardial infarction was confirmed in all mice using TTC staining (Figure 2). The TI0 was defined as the TI value, which s the SI of the non-infarcted (viable) myocardium. This value was unique for each mouse and ranged from 220 to 300 msec (Figure 3). The SNR in the viable myocardium was at its minimum (17.2 ± 2.4, ranging from 12.8 to 23.1) for a mean TI of 268 msec ± 27.3 corresponding to the optimal TI (referred to as TI0). Mean SNR, CNR and relative SI at TI0 are reported in Table 1. The minimum SNR, at TI0, in the viable myocardium (17.2 ± 2.4) was significantly different from that found in the infarcted myocardium (82.1 ± 10.8; p = 0.006) but not from the SNR in the blood (48.7 ± 16.6, p = 0.126). The mean CNR of infarcted tissue compared with viable myocardium was 76.6 ± 19.8, whereas infarcted tissue compared with blood was 25.7 ± 14.7, and blood compared with viable myocardium was 40.6 ± 21.2. The mean maximum relative SI of the infarcted tissue compared with viable myocardium was 344.9 ± 60.4% (Figure 4), and occurred at TI0 when SI of the viable myocardium was minimum, leading to an optimal CNR between viable and infarcted myocardial areas.

Bottom Line: Contrast-to-noise (CNR) and signal-to-noise ratio (SNR) were measured and compared for each myocardial region of interest (ROI).The optimal TI, which corresponded to a minimum SNR in the normal myocardium, was 268 ms +/- 27.3.The SNR in the viable myocardium was significantly different from that found in the infarcted myocardium (17.2 +/- 2.4 vs 82.1 +/- 10.8; p = 0.006) leading to a maximal relative SI (Signal Intensity) between those two areas (344.9 +/- 60.4).

View Article: PubMed Central - HTML - PubMed

Affiliation: Stem Cell Imaging, MRC Clinical Sciences Centre, Hammersmith Hospital, Imperial College London, UK. catherine.chapon@univ-angers.fr

ABSTRACT

Purpose: To demonstrate the feasibility of using an inversion recovery pulse sequence and to define the optimal inversion time (TI) to assess myocardial infarction in mice by late gadolinium enhancement (LGE) MRI at 9.4T, and to obtain the maximal contrast between the infarcted and the viable myocardium.

Methods: MRI was performed at 9.4T in mice, two days after induction of myocardial infarction (n = 4). For cardiovascular MR imaging, a segmented magnetization-prepared fast low angle shot (MP-FLASH) sequence was used with varied TIs ranging from 40 to 420 ms following administration of gadolinium-DTPA at 0.6 mmol/kg. Contrast-to-noise (CNR) and signal-to-noise ratio (SNR) were measured and compared for each myocardial region of interest (ROI).

Results: The optimal TI, which corresponded to a minimum SNR in the normal myocardium, was 268 ms +/- 27.3. The SNR in the viable myocardium was significantly different from that found in the infarcted myocardium (17.2 +/- 2.4 vs 82.1 +/- 10.8; p = 0.006) leading to a maximal relative SI (Signal Intensity) between those two areas (344.9 +/- 60.4).

Conclusion: Despite the rapid heart rate in mice, our study demonstrates that LGE MRI can be performed at 9.4T using a protocol similar to the one used for clinical MR diagnosis of myocardial infarction.

Show MeSH
Related in: MedlinePlus