Opencage radio frequency coil for magnetic resonance imaging

International audienc

3D MRI of explanted sheep hearts with submillimeter isotropic spatial resolution: comparison between diffusion tensor and structure tensor imaging

OBJECTIVE: The aim of the study is to compare structure tensor imaging (STI) with diffusion tensor imaging (DTI) of the sheep heart (approximately the same size as the human heart). MATERIALS AND METHODS: MRI acquisition on three sheep ex vivo hearts was performed at 9.4 T/30 cm with a seven-element RF coil. 3D FLASH with an isotropic resolution of 150 µm and 3D spin-echo DTI at 600 µm were performed. Tensor analysis, angles extraction and segments divisions were performed on both volumes. RESULTS: A 3D FLASH allows for visualization of the detailed structure of the left and right ventricles. The helix angle determined using DTI and STI exhibited a smooth transmural change from the endocardium to the epicardium. Both the helix and transverse angles were similar between techniques. Sheetlet organization exhibited the same pattern in both acquisitions, but local angle differences were seen and identified in 17 segments representation. DISCUSSION: This study demonstrated the feasibility of high-resolution MRI for studying the myocyte and myolaminar architecture of sheep hearts. We presented the results of STI on three whole sheep ex vivo hearts and demonstrated a good correspondence between DTI and STI

3D high resolution imaging of human heart for visualization of the cardiac structure

Imaging of cardiac structure is thus essential for understanding both electrical propagation and efficient contraction in human models. The processing pipeline of diffusion tensor imaging (DTI) and structure tensor imaging (STI) is described and the first ex vivo demonstration of this approach in a human heart is provided at 9.4T. A human heart was fixed in formaldehyde with gadolinium then immersed in Fomblin. MRI acquisitions were performed at 9.4T/30 cm with a 7 elements transmit/receive coil. 3D spin-echo DTI at 600 × 600 × 600 µm(3) and 3D FLASH echo image at 150 × 150 × 150 µm(3) were produced. Tensor extraction and analysis were performed on both volumes. 3D gradient echo at 150 × 150 × 150 (µ)m3 allows direct visualization of detailed structure of LV. Abrupt change in sheetlet orientation is observed in the LV and is confirmed with STI. The DTI helix angle has a smooth transmural change from endocardium to epicardium. Both the helix and transverse angles are shown to be similar between DTI and STI. The sheetlet organization between both acquisitions displays the same pattern even though local angle differences are demonstrated. In conclusion, these preliminary results are promising for investigating 3D structural characterization of normal/pathologic cardiac organization in human. It opens new perspectives to better understand the links between structural remodeling and electrical disorders of the heart