International Conference on Medical Imaging & Diagnosis October 20-21, 2016 Chicago, Illinois, USA

Bin Zhu is the Director of the Department of Radiology, Affiliated Drum Tower Hospital, Nanjing University School of Medicine. He has published more than 30 papers in reputed journals and has been serving as an Editorial Board Member of repute.

Magnetic resonance (MR) imaging along with the development of SPIO nanoparticle have a promising effect on tracking of stem cells. However, SPIOs are no longer being manufactured. Therefore, it is urgent to find out a new reagent to label cells for in vivo monitoring. The present study aims to evaluate the efficiency and the safety of labeling minipigmesenchymal stem cells (MSCs) with ferumoxytol- poly-l-lysine (PLL). MSCs were cultured and incubated with ferumoxytol-PLL. Labeling efficiency was. The effect of ferumoxytol-PLL at iron concentration of 50ug/ml on cell viability, cell migration, proliferation and cell cycle were determined by MTT assay, transwell migration assay, 5-ethynyl-2´-deoxyuridine (EdU) staining assay and flow cytometryanlaysis respectively. A 1.5T MR system with T2*mapping sequences was used for in-vitro and in-vivo MR imaging. The labeling efficiency was 100%. The iron content of each cell was liner correlated with the iron concentration of the labeling media (p<0.05). There were not significant impairments were documented in cell viability, proliferation, migration and cell cycles at 50 μg/ml (p>0.05).The ferumoxytol-PLL labeling caused a stronger low signal attenuation effect on T2*WI. T2*value were negatively correlated with cell numbers and iron concentration of the labeling media, and positively correlated with cell culturing passages (p<0.05). Hypointense signals on T2*-weighed images were detected in infarcted myocardium after transplantation of MSCs pre-labeled with ferumoxytol-PLL. Significant increases in graft area and T2* value were observed 7 days follow-up versus 1 day (p<0.05). Further increase in T2*value occurred at 15 days (p<0.05), paralleled with a decrease in graft area (p<0.05). The result of Prussian blue staining was closely corresponded to MR findings. Ferumoxytol-PLL labeled MSCs can significantly shorten the T2* value without interference in cells’ biological features. In-vivo MRI visualization in infarcted myocardium is feasible.

Shivaram Poigai Arunachalam is a Research Engineer in the Department of Radiology, in Mayo Clinic, Rochester, MN USA. He works on developing technical tools for cardiac magnetic resonance eleastorgraphy imaging for non-invasive assesment of myocardial stiffness in vivo which can be useful in the prognosis and diagnosis of vareity of cardiac diseases. He is also a final year PhD candidate in the Department of Biomedical Engineering at the University of Minnesota, Minneapolis, MN working on developing novel cardiac mapping systems for Atrial Fibrillation (AF).

Myocardial stiffness is a novel biomarker with both diagnostic and prognostic potential in a range of cardiac diseases such as ischemia or myocardial infarction known to have increased stiffness. Application of Magnetic Resonance Elastography (MRE) to the heart enables measurement of myocardial stiffness in vivo. This study was performed to assess the feasibility of measuring in vivo myocardial stiffness during systole and diastole in a pig using 3D MRE. A custom passive driver was placed on the chest and imaging was performed in prone position on a 1.5 Tesla whole body MR imager (Signa Excite; GE) with a 4-channel coil in oblique plane using ECG-gated spin-echo echo planar imaging sequence at 140 Hz vibration frequency with 5 breath holds of approximately 25 seconds. Systolic and diastolic short-axis acquisition was performed prescribing corresponding time delays observed from a FIESTA cine scan. Acquisition parameters: 1 shot, NEX=1; TR/TE=4600/52ms; FOV=28.8 cm; 96x96 image matrix; 11 continuous 3 mm thick slices with 0 mm spacing, isotropic acquisition; 2 motion-encoding gradient (MEG) pairs; x, y, and z motion-encoding directions; ASSET=2, and 4 phase offsets. MRE stiffness was obtained using 3D direct inversion algorithm and an ROI covering the left ventricle was used to report stiffness. The mean stiffness of the myocardium in systole was 6.3 kPa and 4.5 kPa in diastole. The results indicate that 3D MRE can differentiate systolic and diastolic myocardial stiffness. Follow up studies with a larger sample size are underway to further validate these findings.