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Assessment of Myocardial Fibrosis in Mice Using a T2*-Weighted 3D Radial Magnetic Resonance Imaging Sequence.

van Nierop BJ, Bax NA, Nelissen JL, Arslan F, Motaal AG, de Graaf L, Zwanenburg JJ, Luijten PR, Nicolay K, Strijkers GJ - PLoS ONE (2015)

Bottom Line: Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis.Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts.However, in vivo contrast on subtraction images was rather poor, hampering a straightforward visual assessment of the spatial distribution of the fibrotic tissue.

View Article: PubMed Central - PubMed

Affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.

ABSTRACT

Background: Myocardial fibrosis is a common hallmark of many diseases of the heart. Late gadolinium enhanced MRI is a powerful tool to image replacement fibrosis after myocardial infarction (MI). Interstitial fibrosis can be assessed indirectly from an extracellular volume fraction measurement using contrast-enhanced T1 mapping. Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis.

Objective: To goal of this paper was to explore the use of a T2*-weighted radial sequence for the visualization of fibrosis in mouse heart.

Methods: C57BL/6 mice were studied with MI (n = 20, replacement fibrosis), transverse aortic constriction (TAC) (n = 18, diffuse fibrosis), and as control (n = 10). 3D center-out radial T2*-weighted images with varying TE were acquired in vivo and ex vivo (TE = 21 μs-4 ms). Ex vivo T2*-weighted signal decay with TE was analyzed using a 3-component model. Subtraction of short- and long-TE images was used to highlight fibrotic tissue with short T2*. The presence of fibrosis was validated using histology and correlated to MRI findings.

Results: Detailed ex vivo T2*-weighted signal analysis revealed a fast (T2*fast), slow (T2*slow) and lipid (T2*lipid) pool. T2*fast remained essentially constant. Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts. T2*slow correlated with the presence of diffuse fibrosis in TAC hearts (r = 0.82, P = 0.01). Ex vivo and in vivo subtraction images depicted a positive contrast in the infarct co-localizing with the scar. Infarct volumes from histology and subtraction images linearly correlated (r = 0.94, P<0.001). Region-of-interest analysis in the in vivo post-MI and TAC hearts revealed significant T2* shortening due to fibrosis, in agreement with the ex vivo results. However, in vivo contrast on subtraction images was rather poor, hampering a straightforward visual assessment of the spatial distribution of the fibrotic tissue.

No MeSH data available.


Related in: MedlinePlus

T2*-weighted MR images of a post-MI mouse heart.Two short-axis and long-axis cross-sections through an in vivo T2*-weighted dataset (TE = 21 μs) of a post-MI mouse heart. Indicated are the right ventricle (RV), left ventricle (LV), the papillary muscles (PM) and some small artefacts (↖). A dark saturation band with low signal intensity is visible in the two long-axis images.
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pone.0129899.g004: T2*-weighted MR images of a post-MI mouse heart.Two short-axis and long-axis cross-sections through an in vivo T2*-weighted dataset (TE = 21 μs) of a post-MI mouse heart. Indicated are the right ventricle (RV), left ventricle (LV), the papillary muscles (PM) and some small artefacts (↖). A dark saturation band with low signal intensity is visible in the two long-axis images.

Mentions: In vivo imaging of replacement and diffuse fibrosis in the mouse models was performed with cardiac triggered versions of the T2*-weighted sequence. The resulting basic image quality was adequate, as demonstrated for a post-MI mouse heart (Fig 4). Left and right ventricular wall, papillary muscles and infarct area, as well as the surrounding anatomy of ribs and lungs could be clearly distinguished. The dark bands in the long-axis images resulted from the saturation slice to suppress blood signal in the LV lumen.


Assessment of Myocardial Fibrosis in Mice Using a T2*-Weighted 3D Radial Magnetic Resonance Imaging Sequence.

van Nierop BJ, Bax NA, Nelissen JL, Arslan F, Motaal AG, de Graaf L, Zwanenburg JJ, Luijten PR, Nicolay K, Strijkers GJ - PLoS ONE (2015)

T2*-weighted MR images of a post-MI mouse heart.Two short-axis and long-axis cross-sections through an in vivo T2*-weighted dataset (TE = 21 μs) of a post-MI mouse heart. Indicated are the right ventricle (RV), left ventricle (LV), the papillary muscles (PM) and some small artefacts (↖). A dark saturation band with low signal intensity is visible in the two long-axis images.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482648&req=5

pone.0129899.g004: T2*-weighted MR images of a post-MI mouse heart.Two short-axis and long-axis cross-sections through an in vivo T2*-weighted dataset (TE = 21 μs) of a post-MI mouse heart. Indicated are the right ventricle (RV), left ventricle (LV), the papillary muscles (PM) and some small artefacts (↖). A dark saturation band with low signal intensity is visible in the two long-axis images.
Mentions: In vivo imaging of replacement and diffuse fibrosis in the mouse models was performed with cardiac triggered versions of the T2*-weighted sequence. The resulting basic image quality was adequate, as demonstrated for a post-MI mouse heart (Fig 4). Left and right ventricular wall, papillary muscles and infarct area, as well as the surrounding anatomy of ribs and lungs could be clearly distinguished. The dark bands in the long-axis images resulted from the saturation slice to suppress blood signal in the LV lumen.

Bottom Line: Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis.Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts.However, in vivo contrast on subtraction images was rather poor, hampering a straightforward visual assessment of the spatial distribution of the fibrotic tissue.

View Article: PubMed Central - PubMed

Affiliation: Biomedical NMR, Department of Biomedical Engineering, Eindhoven University of Technology, Eindhoven, The Netherlands.

ABSTRACT

Background: Myocardial fibrosis is a common hallmark of many diseases of the heart. Late gadolinium enhanced MRI is a powerful tool to image replacement fibrosis after myocardial infarction (MI). Interstitial fibrosis can be assessed indirectly from an extracellular volume fraction measurement using contrast-enhanced T1 mapping. Detection of short T2* species resulting from fibrotic tissue may provide an attractive non-contrast-enhanced alternative to directly visualize the presence of both replacement and interstitial fibrosis.

Objective: To goal of this paper was to explore the use of a T2*-weighted radial sequence for the visualization of fibrosis in mouse heart.

Methods: C57BL/6 mice were studied with MI (n = 20, replacement fibrosis), transverse aortic constriction (TAC) (n = 18, diffuse fibrosis), and as control (n = 10). 3D center-out radial T2*-weighted images with varying TE were acquired in vivo and ex vivo (TE = 21 μs-4 ms). Ex vivo T2*-weighted signal decay with TE was analyzed using a 3-component model. Subtraction of short- and long-TE images was used to highlight fibrotic tissue with short T2*. The presence of fibrosis was validated using histology and correlated to MRI findings.

Results: Detailed ex vivo T2*-weighted signal analysis revealed a fast (T2*fast), slow (T2*slow) and lipid (T2*lipid) pool. T2*fast remained essentially constant. Infarct T2*slow decreased significantly, while a moderate decrease was observed in remote tissue in post-MI hearts and in TAC hearts. T2*slow correlated with the presence of diffuse fibrosis in TAC hearts (r = 0.82, P = 0.01). Ex vivo and in vivo subtraction images depicted a positive contrast in the infarct co-localizing with the scar. Infarct volumes from histology and subtraction images linearly correlated (r = 0.94, P<0.001). Region-of-interest analysis in the in vivo post-MI and TAC hearts revealed significant T2* shortening due to fibrosis, in agreement with the ex vivo results. However, in vivo contrast on subtraction images was rather poor, hampering a straightforward visual assessment of the spatial distribution of the fibrotic tissue.

No MeSH data available.


Related in: MedlinePlus