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Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode.

Chang FY, Tsai MT, Wang ZY, Chi CK, Lee CK, Yang CH, Chan MC, Lee YJ - Sci Rep (2015)

Bottom Line: Also, an algorithm for positioning of the treatment location from OCT images was developed.With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery.This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Chang Gung University, 259, Wen-Hwa 1st Rd., Kwei-Shan Dist., Taoyuan city, 33302, Taiwan.

ABSTRACT
Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

No MeSH data available.


Related in: MedlinePlus

OCT results obtained for various exposure periods to 450-nm LD.(a) Before exposure; after exposure for (b) 3, (c) 6, (d) 9, (e) 12, (f) 15, (g) 18, and (h) 21 s. The ball shape indicated by the white arrow represents the blood leakage from the vessel caused by the needle. The region indicated by the yellow square in (a) is enlarged as shown in the right-lower corners.
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f1: OCT results obtained for various exposure periods to 450-nm LD.(a) Before exposure; after exposure for (b) 3, (c) 6, (d) 9, (e) 12, (f) 15, (g) 18, and (h) 21 s. The ball shape indicated by the white arrow represents the blood leakage from the vessel caused by the needle. The region indicated by the yellow square in (a) is enlarged as shown in the right-lower corners.

Mentions: To evaluate the applicability of the integrated system to laser microsurgery, the ear skin of mice were experimented with the OCT-guided laser microsurgery system. To induce blood leakage, the vessel was punched with a needle before OCT scanning. Firstly, an LD with a center wavelength of 450 nm was used to induce blood coagulation. Figure 1 shows the OCT results obtained at various exposure periods: before laser exposure and after exposures for 3, 6, 9, 12, 15, 18, and 21 s. In Fig. 1(a), the ball shape indicated by the white arrow represents the blood leakage from the vessel, caused by the needle. To expose the specific area without damaging the surrounding tissue, the laser beam of the treatment LD was accurately positioned, according to the proposed method of image-based feedback positioning. During laser exposure, the optical beam of treatment LD was positioned at the center of blood drop and fixed without scanning to prevent from extra damage to surrounding tissue. From Fig. 1, it can be found that the leaked blood can be accurately exposed and the blood drop started to shrink after the laser exposure. Furthermore, the results of Fig. 1 showed that the blood started to coagulate after the laser exposure for 3 s. Then, the same experiment was repeated, and the other LD with a center wavelength of 532 nm was substituted for the 450-nm LD and used for laser treatment. Figure 2 shows the OCT images of the ear skin of the other mouse obtained before laser exposure and after the exposures for 3, 6, 9, 12, 15, 18, and 21 s, respectively. Similar to the results in Fig. 1, the blood started to coagulate after the laser exposure for 3 s. In addition, a blood clot can be observed after the laser exposure for 9 s, as shown in Fig. 2(d) and indicated by the white arrow. The results of Figs 1 and 2 showed that the areas indicated by the white arrow decreased as the exposure period increased.


Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode.

Chang FY, Tsai MT, Wang ZY, Chi CK, Lee CK, Yang CH, Chan MC, Lee YJ - Sci Rep (2015)

OCT results obtained for various exposure periods to 450-nm LD.(a) Before exposure; after exposure for (b) 3, (c) 6, (d) 9, (e) 12, (f) 15, (g) 18, and (h) 21 s. The ball shape indicated by the white arrow represents the blood leakage from the vessel caused by the needle. The region indicated by the yellow square in (a) is enlarged as shown in the right-lower corners.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4645164&req=5

f1: OCT results obtained for various exposure periods to 450-nm LD.(a) Before exposure; after exposure for (b) 3, (c) 6, (d) 9, (e) 12, (f) 15, (g) 18, and (h) 21 s. The ball shape indicated by the white arrow represents the blood leakage from the vessel caused by the needle. The region indicated by the yellow square in (a) is enlarged as shown in the right-lower corners.
Mentions: To evaluate the applicability of the integrated system to laser microsurgery, the ear skin of mice were experimented with the OCT-guided laser microsurgery system. To induce blood leakage, the vessel was punched with a needle before OCT scanning. Firstly, an LD with a center wavelength of 450 nm was used to induce blood coagulation. Figure 1 shows the OCT results obtained at various exposure periods: before laser exposure and after exposures for 3, 6, 9, 12, 15, 18, and 21 s. In Fig. 1(a), the ball shape indicated by the white arrow represents the blood leakage from the vessel, caused by the needle. To expose the specific area without damaging the surrounding tissue, the laser beam of the treatment LD was accurately positioned, according to the proposed method of image-based feedback positioning. During laser exposure, the optical beam of treatment LD was positioned at the center of blood drop and fixed without scanning to prevent from extra damage to surrounding tissue. From Fig. 1, it can be found that the leaked blood can be accurately exposed and the blood drop started to shrink after the laser exposure. Furthermore, the results of Fig. 1 showed that the blood started to coagulate after the laser exposure for 3 s. Then, the same experiment was repeated, and the other LD with a center wavelength of 532 nm was substituted for the 450-nm LD and used for laser treatment. Figure 2 shows the OCT images of the ear skin of the other mouse obtained before laser exposure and after the exposures for 3, 6, 9, 12, 15, 18, and 21 s, respectively. Similar to the results in Fig. 1, the blood started to coagulate after the laser exposure for 3 s. In addition, a blood clot can be observed after the laser exposure for 9 s, as shown in Fig. 2(d) and indicated by the white arrow. The results of Figs 1 and 2 showed that the areas indicated by the white arrow decreased as the exposure period increased.

Bottom Line: Also, an algorithm for positioning of the treatment location from OCT images was developed.With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery.This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering, Chang Gung University, 259, Wen-Hwa 1st Rd., Kwei-Shan Dist., Taoyuan city, 33302, Taiwan.

ABSTRACT
Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in biological tissues during laser microsurgery. Instead of high-cost pulsed lasers, continuous-wave laser diodes (CW-LDs) with the central wavelengths of 450 nm and 532 nm are used for blood coagulation, corresponding to higher absorption coefficients of oxyhemoglobin and deoxyhemoglobin. Experimental results showed that the location of laser exposure can be accurately controlled with the proposed approach of imaging-based feedback positioning. Moreover, blood coagulation can be efficiently induced by CW-LDs and the coagulation process can be monitored in real-time with OCT. This technology enables to potentially provide accurate positioning for laser microsurgery and control the laser exposure to avoid extra damage by real-time OCT imaging.

No MeSH data available.


Related in: MedlinePlus