Department of Radiology, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto, 602-8566, Japan.
Department of Mechanical Engineering, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
Cardiovasc Intervent Radiol. 2020 Mar;43(3):514-519. doi: 10.1007/s00270-019-02401-8. Epub 2020 Jan 2.
To elucidate the basic thermophysical properties at low temperatures of lipiodol, which is used as a marker by transarterial injection before CT-guided cryoablation for solid tumors, by fundamental experiments with pure lipiodol phantom.
The freezing point of lipiodol was measured using differential scanning calorimeter (DSC) by detecting differences in the heating rate during heating from - 30 °C. Freezing experiments were conducted using pure lipiodol and a tissue phantom, which were prepared in an acrylic container at 37 °C. The growth of the frozen region was observed for 10 min. Temperatures were monitored at the cryoprobe surface and designated positions around the cryoprobe.
The DSC experiment showed that freezing was observed between - 5 and - 30 °C, which indicated that the freezing point was approximately - 5 °C. Freezing experiments revealed that the diameter of frozen region in the lipiodol was smaller than that in the tissue phantom (5 mm vs 24 mm) after 10-min freezing. The temperature at the probe surface was - 130 °C in lipiodol, which was 25 °C lower than that in the tissue phantom. There was a larger temperature gradient near the cryoprobe in lipiodol due to lower thermal conductivity.
The present results suggest that an extremely high concentration of lipiodol (close to pure lipiodol) potentially reduces frozen region because of its lower freezing point and smaller thermal conductivity. However, since lipiodol concentrations in clinical cases differ from the current model, further studies using models that are close to clinical conditions are required.
No level of evidence, laboratory investigation.
通过使用纯碘化油模型进行基础实验，阐明用于经动脉注射 CT 引导下冷冻消融治疗实体瘤前的标记物——碘化油在低温下的基本热物理性质。
使用差示扫描量热仪（DSC）通过检测从-30°C 加热过程中的升温速率差异来测量碘化油的冰点。在 37°C 的丙烯酸容器中制备纯碘化油和组织模型进行冻结实验。观察 10 分钟内冻结区域的生长情况。监测冷冻探针表面和冷冻探针周围指定位置的温度。
DSC 实验表明，在-5 至-30°C 之间观察到冻结，这表明冰点约为-5°C。冻结实验表明，10 分钟冻结后，碘化油中冻结区域的直径小于组织模型（5mm 比 24mm）。碘化油中探针表面的温度为-130°C，比组织模型低 25°C。由于导热系数较低，碘化油中靠近冷冻探针处的温度梯度较大。
目前的结果表明，极高浓度的碘化油（接近纯碘化油）由于其较低的冰点和较小的导热系数，可能会减小冻结区域。然而，由于临床病例中的碘化油浓度与当前模型不同，因此需要使用更接近临床情况的模型进行进一步研究。
无证据级别，实验室研究。
