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Sylwia Heinze-Paluchowska
Department of Magnetic Resonance Imaging (NZ56)
Introduction
Coronary heart diseases - the single most common cause of death in the EU and US
The animal model of the mouse is gaining increasing popularity in basic cardiovascular research
Deaths by cause, latest available year,Europe
The purpose of our project was to:
design and construct specialized hardware components
develop MR protocols dedicated to measurements of cardiac function of small animals in vivo
evaluate cardiac dynamics in mice receiving pharmacotherapy (clopidogrel, canrenon, antiplatelet teraphy)
Purpose
Animal modelMouse heart’s weight 0,1 g; heart dimensions 13 mm (long axis) and 8 mm (short axis). Heart rate: 400-600 bpm (RR 100-150 ms).
Left atrium Left ventricle
Right atriumRight ventricle
30 mm
End-systole and end-diastole MR images of the left ventricle (LV)
Subjects and Methods:
Cardiac function in TG (Tgq*44) and wild-type (FVB) mice was analyzed using MRI.
Tgq* 44 mice mimics many of the phenotypic characteristics of dilated cardiomyopathy in humans.
Cardiac function was measured in TG and wild-type mice at the age of 2-14 months.
Dobutamine induced stress was used to unmask the alterations in cardiac function at early stage of heart failure progression that was not clearly visible by monitoring cardiac function at rest.
MRI system
4,7T/310 magnet (Bruker, Germany)
MARAN DRX Console (Resonance Instruments Ltd., GB)
Animal monitoring system (SA Instruments Ltd, USA)
Dedicated, homebuilt probehead :
Unshielded gradient system RF birdcage coil Animal handling system Temperature controller
Homebuilt gradient system and RF probehead
MRI of the mice heart MRI of the mice heart in vivoin vivo
Mouse (FVB, Tgq*44)
Animal handling system
RF birdcage coil
4,7 T magnet with MARAN DRX console , device to anaesthesia and animal monitoring system
ECG Anaesthesia
All animal experimental procedures were in accordance with institutional guidelines, given by the Ethic Commission of the Jagiellonian University Medical College.
8
Methodology
MR images acquired through 120% of the cardiac cycle in the short-axis plane at papillary muscles level.
ProtocolECG triggered fast gradient echo (cine-like FLASH with flow-compensation)
TR = 5 ÷ 6 ms TE = 2,5 ms FOV = 30 x 30 mm Slice thickness1,5 mm (1mm) Matrix 128128 NS 8 Flip angle =30
TG mouse
Wild-type mouse
Image analysis
Semiautomatic analysis of the LV images with the use of Aphelion software (prof. L. Wojnar, Cracow University of Technology)
T. Skórka, S. Heinze-Paluchowska, et al., XL Seminar on Nuclear Magnetic Resonance and Its Applications, 2007
Analysis of cardiac function in vivo by MRI
Assessment of cardiac parameters using ECG gated MRI
Ejection Rate ER [1/ms],
Filling Rate FR [1/ms],
Fractional Area Change FAC [%]:
where:
ESA - End Systolic Area
EDA - End Diastolic Area.
100%EDA ESA
FACEDA
Ejection rate (ER) and Filling rate (FR) are equal to absolute value of regression line slopes.
Fractional Contraction is equal to normalized difference between end-diastolic and end-systolic LV slice areas.
Results
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The mean values of the Fractional Area Change for both TG and FVB mice at various ages
Application of homebuilt hardware components and advanced image analysis allowed for rapid image acquisition
Good quality MR images of mouse heart in vivo enabled quantification of cardiac systolic and diastolic dynamics in mice.
Our methodology enabled us to demonstrate that the progression of systolic and diastolic cardiac dysfunction in Tgaq*44 mice displays a different pattern.
Four chamber view of the mouse heart
AcknowledgementsIFJ PAN
dr T. Skórka mgr U. Tyrankiewicz mgr inż. P. Skóra inż. P. Borowiec R. Wiertek prof. dr hab. A. Jasiński dr W. Węglarz
CM UJ dr Ł. Drelicharz prof. dr hab. S. Chłopicki
Politechnika Krakowska prof. dr hab. L. Wojnar
THANK YOU THANK YOU FOR YOUR ATTENTIONFOR YOUR ATTENTION
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