Gayathri K, Shailendhra K
Department of Mathematics, Amrita School of Engineering, Coimbatore, Amrita Vishwa Vidyapeetham, Coimbatore, 641 112, India.
Cardiovasc Eng Technol. 2019 Jun;10(2):242-256. doi: 10.1007/s13239-019-00400-x. Epub 2019 Jan 28.
To explore if there are any adverse effects on blood flow in human beings when they are exposed to high or ultra high intensity magnetic fields in MRI, by investigating both qualitatively and quantitatively the effects of such fields on the velocity of blood and medically significant hemodynamic wall parameters such as wall shear stress (WSS), oscillatory shear index (OSI) and relative residence time (RRT) in four human large arteries.
Blood flow in an artery is approximated as a flow through a uniform circular tube with rigid porous walls and the well-known McDonalds model is employed by using pressure gradient waveforms reported in the medical literature.
No significant change in the above parameters is observed up to 3T in all these arteries except a discernible change in the velocity and RRT in the pulmonary artery. Very significant changes are noticed in the above parameters beyond 8T in the pulmonary artery. The common hypothesis that low WSS and high OSI co-locate is not acceptable.
Our results suggest that the clinical consequences are to be carefully considered before exposing human beings to ultra high field MRI. It may not be appropriate to conclude anything about the effect of magnetic field on blood flow in human beings based on experimental studies on animals, which is one of the reasons for the contradicting reports found in the literature. A slip condition at the wall which is appropriate to hemodynamics is yet to be developed.
通过定性和定量研究高强度或超高强度磁场对人体四根大动脉中血液流速以及医学上重要的血液动力学壁参数（如壁面切应力（WSS）、振荡剪切指数（OSI）和相对停留时间（RRT））的影响，探讨人体在磁共振成像（MRI）中暴露于高强度或超高强度磁场时对血流是否有任何不良影响。
将动脉中的血流近似为通过具有刚性多孔壁的均匀圆形管的流动，并使用医学文献中报道的压力梯度波形采用著名的麦克唐纳模型。
在所有这些动脉中，高达3T时上述参数均未观察到显著变化，但肺动脉中的流速和RRT有明显变化。在肺动脉中，超过8T时上述参数出现非常显著的变化。低WSS和高OSI共定位的常见假设是不可接受的。
我们的结果表明，在让人体暴露于超高场MRI之前，应仔细考虑其临床后果。基于对动物的实验研究来推断磁场对人体血流的影响可能并不合适，这也是文献中出现相互矛盾报告的原因之一。尚未建立适合血液动力学的壁面滑移条件。
