Hsu Christopher P, Razavi Mahmood K, So Samuel K, Parachikov Ilian H, Benaron David A
Santa Clara Valley Medical Center, San Jose, California, USA.
J Vasc Interv Radiol. 2005 Nov;16(11):1473-8. doi: 10.1097/01.rvi.000017833.30967.39.
To determine whether tissue visible light spectroscopy (VLS) used during radiofrequency (RF) ablation of liver tumors could aid in detecting when tissue becomes adequately ablated, locate grossly ablated regions long after temperature and hydration measures would no longer be reliable, and differentiate tumor from normal hepatic tissue based on VLS spectral characteristics.
Studies were performed on human liver in vivo and animal liver ex vivo. In three ex vivo cow livers, RF-induced lesions were created at 80 degrees C. A 28-gauge needle embedded with VLS optical fibers was inserted alongside an RF ablation array, and tissue spectral characteristics were recorded throughout ablation. In one anesthetized sheep in vivo, a VLS needle probe was passed through freshly ablated liver lesions, and ablated region spectral characteristics were recorded during probe transit. In two human subjects, a VLS needle probe was passed through liver tumors in patients undergoing hepatic tumor resection without ablation, and tumor spectral characteristics were recorded during probe transit.
In bovine studies, there was significant change in baseline absorbance (P < .0001) as a result of increased light scattering as liver was ablated. Liver exhibited native differential absorbance peaks at 550 nm that disappeared during ablation, suggesting that optical spectroscopy detects markers of tissue altered during ablation. In sheep, liver gross ablation margins were clearly defined with millimeter resolution during needle transit through the region, suggesting that VLS is sensitive to gross margins of ablation, even after the temperature has normalized. In humans, absorbance decreased as the needle passed from normal tissue into tumor and normalized after emerging from the tumor, suggesting that absence of native liver pigment may serve as a marker for the gross margins and presence of tumors of extrahepatic origin.
In human subjects, VLS during RF liver tumor ablation depicted gross hepatic tumor margins in real time; in animal subjects, VLS achieved monitoring of when and where RF ablation endpoints were achieved, even long after the tissue cooled. Real-time in vivo monitoring and treatment feedback may be possible with the use of real-time VLS sensors placed along side of, or embedded into, the RF probe, which can then be used as an adjunct to standard imaging during tumor localization and RF ablation treatment.
确定在肝脏肿瘤射频消融过程中使用组织可见光光谱（VLS）是否有助于检测组织何时充分消融，在温度和水化测量不再可靠后很长时间定位大体消融区域，并根据VLS光谱特征区分肿瘤与正常肝组织。
对人体肝脏进行体内研究，对动物肝脏进行体外研究。在三个离体牛肝脏中，在80℃下产生射频诱导损伤。将一根嵌入VLS光纤的28号针与射频消融阵列并排插入，在整个消融过程中记录组织光谱特征。在一只麻醉的绵羊体内，将VLS针式探头穿过刚消融的肝脏病变，在探头穿过期间记录消融区域的光谱特征。在两名人类受试者中，将VLS针式探头穿过正在接受肝肿瘤切除但未进行消融的患者的肝肿瘤，在探头穿过期间记录肿瘤光谱特征。
在牛的研究中，由于肝脏消融导致光散射增加，基线吸光度有显著变化（P <.0001）。肝脏在550nm处呈现天然的差分吸收峰，在消融过程中消失，这表明光谱学检测到了消融过程中组织改变的标志物。在绵羊中，当针穿过该区域时，肝脏大体消融边缘以毫米分辨率清晰界定，这表明VLS对大体消融边缘敏感，即使在温度恢复正常后也是如此。在人类中，当针从正常组织进入肿瘤时吸光度降低，从肿瘤中穿出后吸光度恢复正常，这表明缺乏天然肝色素可能是大体边缘和肝外起源肿瘤存在的标志物。
在人类受试者中，射频肝脏肿瘤消融期间的VLS实时描绘了肝脏肿瘤的大体边缘；在动物受试者中，VLS实现了对射频消融终点何时何地达到的监测，即使在组织冷却后很长时间也是如此。使用与射频探头并排或嵌入其中的实时VLS传感器可能实现实时体内监测和治疗反馈，然后可在肿瘤定位和射频消融治疗期间用作标准成像的辅助手段。
