What is the clinical evidence from this study?

Study design: Other. Population: Cardiac hypertrophy (n=24). Intervention: Magnetic resonance imaging (MRI) vs. Necropsy and wild-type controls. Primary outcome: Left ventricle (LV) mass (r2 = 0.95, p=< 0.0001).

February 1, 1998Open Access

Magnetic resonance imaging accurately estimates LV mass in a transgenic mouse model of cardiac hypertrophy

Q: What are the key findings of this study?

Magnetic resonance imaging accurately estimated LV mass in mice, showing excellent correlation with necropsy (r2 = 0.95) and detecting hypertrophy in GCA -/- mice (226 vs 156 mg; P<0.0001).

Key Result

Magnetic resonance imaging accurately estimated LV mass in mice, showing excellent correlation with necropsy (r2 = 0.95) and detecting hypertrophy in GCA -/- mice (226 vs 156 mg; P<0.0001).

Structured PICO

Does MRI accurately estimate LV mass compared to necropsy in a transgenic mouse model of cardiac hypertrophy?

Population

Transgenic mice with a dysfunctional guanylyl cyclase A gene (GCA -/-) that develop hypertension and cardiac hypertrophy, and wild-type siblings as controls (n=24 total; 14 GCA -/-, 10 controls).

Intervention

Gated multislice, multiphase cine MRI at 1.5 T using Simpson's rule to estimate left ventricle (LV) mass and volumes.

Comparator

Necropsy (for validation of LV mass) and wild-type siblings (for comparison of cardiac phenotype).

Outcome

Correlation between LV mass evaluated by MRI and at necropsy.surrogate

MRI at 1.5 T provides an accurate, noninvasive method to assess LV mass and cardiac phenotype in murine models of hypertrophy, correlating excellently with necropsy.

Main Result

Effect estimate: r2 = 0.95

Absolute Event Rate: 226% vs 156%

p-value: p=< 0.0001

Abstract

Transgenic mice with a dysfunctional guanylyl cyclase A gene (GCA -/-) are unable to transduce the signals from atrial naturetic peptide and develop hypertension and cardiac hypertrophy. Magnetic resonance imaging (MRI) was performed to assess cardiac hypertrophy in these animals, using wild-type siblings as controls. Anesthetized mice were studied by gated multislice, multiphase cine MRI at 1.5 T. Simpson's rule was used to estimate left ventricle (LV) mass and volumes from short-axis images. Correlation between LV mass evaluated by MRI and at necropsy was excellent, with LVnecropsy = 1.04 x LVMRI + 4.69 mg (r2 = 0.95). By MRI, GCA -/- LV mass was significantly different when compared with isogenic controls GCA -/-, 226 +/- 43 mg (n = 14) vs. controls, 156 +/- 14 mg (n = 10); P < 0.0001. LV volumes and ejection fraction in the two groups were not significantly different. MRI provides an accurate means for the noninvasive assessment of murine cardiac phenotype and may be useful in following the effects of genetic modification.

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