【演講】2010年皮膚科年會研究論文發表－王修含診所皮膚科王修含醫師皮膚科學研究小站

2010年台灣皮膚科醫學會年會研究論文發表-雷射光熱治療之即時定量式腫瘤活體熱影像技術

Technique for real-time in vivo quantitative thermal imaging during laser-induced thermotherapy in tumor treatment
雷射光熱治療之即時定量式腫瘤活體熱影像技術
王修含1, 2 魏振瑋3 李百祺1, 3 紀秀華2
1國立臺灣大學生醫電子與資訊學研究所
2國立臺灣大學醫學院附設醫院皮膚部
3國立臺灣大學電機工程學系

背景：連續波雷射誘導熱治療可藉由加熱來破壞腫瘤。與抗體連結的金奈米桿可特定性地與腫瘤結合，實現電漿光熱治療，以達到更好的治療效率。在電漿光熱治療的過程，非侵入式的光聲技術可用來監測局部溫度，並可結合超音波產生解剖學影像。但迄今尚未開發出可應用於活體治療的即時定量式光聲熱影像技術。

目的：利用光聲技術，實現可應用於電漿光熱治療的即時活體定量式熱造影，以增進治療安全性與效率。

方法：含有石墨的瓊脂糖凝膠可用於仿體研究。在活體動物實驗中，則使用皮下接種OECM1鱗狀細胞癌的NOD-SCID雄性小鼠。利用脈衝式雷射可產生光聲信號的振幅。在光聲造影時，金奈米桿可用來強化光聲信號的對比。我們設計一套結合超音波與光聲影像的雙模系統，可定位腫瘤並辨識奈米粒子。Grüneisen 參數可決定聲壓振幅，而在軟組織內，此參數與溫度呈線性相關，因此可用於監測溫度的技術，並進一步擴展為二維空間的定量式熱造影技術。

結果：在仿體實驗中，可精確地測量雷射照射區域的溫度，並進而描繪出定量式的熱影像。採用特定抗體連結的金奈米桿，可實現選擇性的標靶式熱治療。在活體實驗中，定量式熱影像可應用於受到雷射照射的腫瘤，並證實此技術之可行性。在熱治療後，對腫瘤進行病理檢查，可發現腫瘤架構受到破壞，但周邊與腫瘤內的非癌化細胞，雖然同時受到連續波雷射的照射，但卻未受到破壞。

Fig. 1 The temperature and the PA-signal amplitude have highly linear relationship.

Fig. 2 Bimodal images obtained before (a) and 30 minutes after (b) injecting nanorods. After injecting the nanorods but without LIT, a significant PA signal appeared in the hypoechoic tumor region which can be detected with pulsed laser (blue arrows). (US: grayscale, PA signal: pseudocolor)

Fig. 3 A quantitative 2-D in vivo thermal image of the laser irradiated tumor region. The core region reached the hyperthermic condition which can kill the tumor cells.

結論：本研究顯示標靶式電漿光熱治療可藉由連結抗體的金奈米桿，選擇性地滅殺腫瘤細胞。在活體熱治療的過程中，可利用光聲技術實現即時定量式的熱影像造影。

Fig. 4 (a) Thermotherapy selectively destroyed the tumor structure which compatible with the thermal imaging. The peripheral tissue was preserved. (b, c) Necrotic tumor cells (red arrows) and intact fibroblasts within the tumor (green arrows). (d) Intact hair follicles near the tumor (yellow arrows) despite being irradiated by the CW laser.

Technique for real-time in vivo quantitative thermal imaging during laser-induced thermotherapy in tumor treatment
雷射光熱治療之即時定量式腫瘤活體熱影像技術

Shiou-Han Wang1, 2, MD, MS; Chen-Wei Wei3, PhD; Pai-Chi Li1, 3, PhD; Shiou-Hwa Jee2, MD, PhD
1Graduate Institute of Biomedical Electronic and Bioinformatics, National Taiwan University
2Department of Dermatology, National Taiwan University Hospital and National Taiwan University College of Medicine
3Department of Electrical Engineering, National Taiwan University

BACKGROUND: Continuous wave (CW) laser-induced thermotherapy (LIT) can generate heat to destruct tumor. Antibody-conjugated gold nanorods (AuNRs) can specifically bind to tumor to facilitate higher therapeutic efficacy to implement plasmonic photothermal therapy (PPTT). During PPTT, a noninvasive photoacoustic (PA) technique may monitor the local temperature, and ultrasound (US) can be combined for anatomical imaging. However, in vivo real-time quantitative PA thermal mapping has not been carried out yet.

OBJECTIVES: With PA technique, we desired to achieve real-time in vivo thermal mapping quantitatively during PPTT for better therapeutic safety and efficacy.

METHODS: Agarose gel containing graphite was used for phantom study. NOD-SCID male mice subcutaneously inoculated with the OECM1 squamous cell carcinoma were used for in vivo animal experiment. The amplitude of the PA signal was generated with a pulsed laser. During PA imaging, the PA-signal contrast was augmented with AuNRs. We designed a bimodal system employing both US and PA images to locate the tumor and recognize nanoparticles. The Grüneisen parameter determines the acoustic pressure amplitude and is linearly related to the temperature of soft tissue. This parameter can be applied for temperature monitoring technique, and further utilized to construct the two dimensional quantitative thermal imaging.

RESULTS: The temperature and the thermal mapping of laser-irradiated area can be exactly measured and drawn quantitatively in the phantom study. Targeted thermotherapy could be implemented selectively by using specific antibodies-conjugated AuNRs. The quantitative thermal image of the laser-irradiated tumor was produced in the in vivo study to confirm this technique. The tumor was examined pathologically after thermotherapy. Destroyed tumor architecture and preserved peripheral and intratumor noncarcinoma cells were found despite irradiated by the CW laser simultaneously.

CONCLUSIONS: The study showed that targeted PPTT can be performed with antibody-conjugated AuNRs to selectively eradicate tumor cells. During in vivo thermotherapy, real-time quantitative thermal imaging can be achieved with PA technique.