Lawrence Livermore National Laboratory, Livermore, CA, USA.
Acad Radiol. 2011 Mar;18(3):270-6. doi: 10.1016/j.acra.2010.09.010. Epub 2010 Nov 13.
The aims of this study were to assess resistive heating of microwires used for remote catheter steering in interventional magnetic resonance imaging and to investigate the use of alumina to facilitate heat transfer to saline flowing in the catheter lumen.
A microcoil was fabricated using a laser lathe onto polyimide-tipped or alumina-tipped endovascular catheters. In vitro testing was performed on a 1.5-T magnetic resonance system using a vessel phantom, body radiofrequency coil, and steady-state pulse sequence. Resistive heating was measured with water flowing over a polyimide-tip catheter or saline flowing through the lumen of an alumina-tip catheter. Preliminary in vivo testing in porcine common carotid arteries was conducted with normal blood flow or after arterial ligation when current was applied to an alumina-tip catheter for up to 5 minutes.
After application of up to 1 W of direct current power, clinically significant temperature increases were noted with the polyimide-tip catheter: 23°C/W at zero flow, 13°C/W at 0.28 cm(3)/s, and 7.9°C/W at 1 cm(3)/s. Using the alumina-tip catheter, the effluent temperature rise using the lowest flow rate (0.12 cm(3)/s) was 2.3°C/W. In vivo testing demonstrated no thermal injury to vessel walls at normal and zero arterial flow.
Resistive heating in current carrying wire pairs can be dissipated by saline coolant flowing within the lumen of a catheter tip composed of material that facilitates heat transfer.
本研究旨在评估用于介入磁共振成像的远程导管转向的微波丝的电阻加热，并研究使用氧化铝来促进向在导管管腔中流动的盐水中的传热。
使用激光车床在聚酰亚胺尖端或氧化铝尖端的血管内导管上制造微线圈。在 1.5-T 磁共振系统上使用血管体模、体部射频线圈和稳态脉冲序列进行体外测试。在聚酰亚胺尖端导管上流动的水或在氧化铝尖端导管的管腔中流动的盐水测量电阻加热。在猪颈总动脉中进行了初步的体内测试，在正常血流或动脉结扎后，当向氧化铝尖端导管施加电流长达 5 分钟时，进行了测试。
施加高达 1 W 的直流电后，聚酰亚胺尖端导管出现临床显著的温度升高：零流量时为 23°C/W，0.28 cm³/s 时为 13°C/W，1 cm³/s 时为 7.9°C/W。使用氧化铝尖端导管，最低流速（0.12 cm³/s）下的流出物温度升高为 2.3°C/W。体内测试表明在正常和零动脉血流下，血管壁没有热损伤。
在由促进传热的材料制成的导管尖端内流动的盐水中，可以消散载流导线对中的电阻加热。
