Developmental changes of cardiac function and mass assessed with MRI in neonatal, juvenile, and adult mice

Abstract

Cardiovascular transgenic mouse models with an early phenotype or even premature death require noninvasive imaging methods that allow for accurate visualization of cardiac morphology and function. Thus the purpose of our study was to assess the feasibility of magnetic resonance imaging (MRI) to characterize cardiac function and mass in newborn, juvenile, and adult mice. Forty-five C57bl/6 mice from seven age groups (3 days to 4 mo after birth) were studied by MRI under isoflurane anesthesia. Electrocardiogram-gated cine MRI was performed with an in-plane resolution of (78-117 microm)(2). Temporal resolution per cine frame was 8.6 ms. MRI revealed cardiac anatomy in mice from all age groups with high temporal and spatial resolution. There was close correlation between MRI- and autopsy-determined left ventricular (LV) mass (r = 0.95, SE of estimate = 9.5 mg). The increase of LV mass (range 9.6-101.3 mg), cardiac output (range 1.1-14.3 ml/min), and stroke volume (range 3. 2-40.2 microl) with age could be quantified by MRI measurements. Ejection fraction and cardiac index did not change with aging. However, LV mass index decreased with increasing age (P < 0.01). High-resolution MRI allows for accurate in vivo assessment of cardiac function in neonatal, juvenile, and adult mice. This method should be useful when applied in transgenic mouse models.

In vivo assessment of absolute perfusion and intracapillary blood volume in the murine myocardium by spin labeling magnetic resonance imaging

“…Combining this with typical body masses and cardiac outputs given in Ref. (22) shows that the whole blood volume circulates once in about 4.5 s. Since this is in the range of the duration of the T 1 quantification, a proper spin inversion within the whole mouse is mandatory.…”

In Vivo Echocardiographic Detection of Cardiovascular Lesions in Apolipoprotein E-Knockout Mice Using a Novel High-Frequency High-Speed Echocardiography Technique.

“…Magnetic resonance imaging (MRI) may be a promising technique for assessing the murine heart; 14, 15 Fayad et al reported noninvasive in vivo high-resolution MRI with a high field magnet (9.4 T) of atherosclerotic lesions in apoE-KO mice, 16 but no information was provided about the morphological and functional changes of the thoracic aorta, aortic valve or heart. Compared with echocardiography, MRI has potential limitations in time resolution and needs ECG and respiratory gating to obtain a motion image, which is then reconstructed after data acquisition of multiple cardiac beats.…”

Multimodality optical imaging of embryonic heart microstructure

“…Structural imaging of the heart in vivo has been demonstrated using a variety of noninvasive imaging modalities such as micro-MRI in adult pigs 35 and adult mice, 36 micro-CT in adult pigs 37 and adult mice, 38 ultrasound in mouse embryos, 39 and positron emission tomography (PET) in adult dogs 40 and adult mice. 41 Optical techniques enable imaging of the embryonic heart at higher resolution.…”