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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

Estimated areas of the blood drops before and after laser exposures at various time points. The representative results from mice exposed with either a 450-nm LD (n = 3) or a 532-nm LD (n = 3) are shown . The lower and upper figures represent the estimated areas of the blood drops with 450-nm and 532-nm laser exposures for various periods.
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f4: Estimated areas of the blood drops before and after laser exposures at various time points. The representative results from mice exposed with either a 450-nm LD (n = 3) or a 532-nm LD (n = 3) are shown . The lower and upper figures represent the estimated areas of the blood drops with 450-nm and 532-nm laser exposures for various periods.

Mentions: Blood coagulation is a process to protect the damaged tissue and vessel following repair. However, for patients with blood coagulation disorders or undergoing surgery, dysfunctional coagulation causes bleeding or obstructive clotting. In this study, we develop an OCT-guided laser microsurgery system for blood coagulation with CW-LDs which can efficiently reduce the system cost. In addition, a method is proposed for accurate selection and positioning of the treatment location to avoid additional damage to the surrounding tissue. To quantitatively evaluate the morphological change as a function of exposure time, the areas of blood drops at various exposure periods were estimated, which was according to the proposed algorithm in the previous study23. Figure 4 shows the representative results from mice exposed with either a 450-nm LD (n = 3) or a 532-nm LD (n = 3). The lower and upper figures in Fig. 4 represent the estimated areas of the blood drops with 450-nm and 532-nm laser exposures for various exposure periods, which were estimated from the top-view images of 3D OCT results. The results showed that the areas of blood drops became smaller after laser exposure, indicating that leaked blood coagulated after the laser exposure for 3 s. As the exposure time was continuous to be increased, the areas of blood drops didn’t show a significant change. Based on the higher extinction coefficients resulting from the absorption of oxyhemoglobin and deoxyhemoglobin, two CW-LDs centered at 450 and 532 nm were used for experiments, and the results showed that both LDs can successfully induce blood coagulation. In comparison of the results of 450-nm LD and 532-nm LD exposures, the blood can be more efficiently coagulated after 450-nm LD exposure with the same exposure power, resulting from the higher extinction coefficient at 450 nm. However, the velocity of blood coagulation can be further improved by increasing the output power of CW-LDs. The results also showed that the treatment location can be precisely positioned and that the treatment outcome can be monitored with real-time coregistration. In the evaluation of the correlation coefficients, blood leakage and the suspension of bleeding were observed. The results showed that the proposed OCT-guided microsurgery system could be a powerful tool for various clinical applications such as dermatology, ophthalmology, and liver and brain surgery.


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)

Estimated areas of the blood drops before and after laser exposures at various time points. The representative results from mice exposed with either a 450-nm LD (n = 3) or a 532-nm LD (n = 3) are shown . The lower and upper figures represent the estimated areas of the blood drops with 450-nm and 532-nm laser exposures for various periods.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Estimated areas of the blood drops before and after laser exposures at various time points. The representative results from mice exposed with either a 450-nm LD (n = 3) or a 532-nm LD (n = 3) are shown . The lower and upper figures represent the estimated areas of the blood drops with 450-nm and 532-nm laser exposures for various periods.
Mentions: Blood coagulation is a process to protect the damaged tissue and vessel following repair. However, for patients with blood coagulation disorders or undergoing surgery, dysfunctional coagulation causes bleeding or obstructive clotting. In this study, we develop an OCT-guided laser microsurgery system for blood coagulation with CW-LDs which can efficiently reduce the system cost. In addition, a method is proposed for accurate selection and positioning of the treatment location to avoid additional damage to the surrounding tissue. To quantitatively evaluate the morphological change as a function of exposure time, the areas of blood drops at various exposure periods were estimated, which was according to the proposed algorithm in the previous study23. Figure 4 shows the representative results from mice exposed with either a 450-nm LD (n = 3) or a 532-nm LD (n = 3). The lower and upper figures in Fig. 4 represent the estimated areas of the blood drops with 450-nm and 532-nm laser exposures for various exposure periods, which were estimated from the top-view images of 3D OCT results. The results showed that the areas of blood drops became smaller after laser exposure, indicating that leaked blood coagulated after the laser exposure for 3 s. As the exposure time was continuous to be increased, the areas of blood drops didn’t show a significant change. Based on the higher extinction coefficients resulting from the absorption of oxyhemoglobin and deoxyhemoglobin, two CW-LDs centered at 450 and 532 nm were used for experiments, and the results showed that both LDs can successfully induce blood coagulation. In comparison of the results of 450-nm LD and 532-nm LD exposures, the blood can be more efficiently coagulated after 450-nm LD exposure with the same exposure power, resulting from the higher extinction coefficient at 450 nm. However, the velocity of blood coagulation can be further improved by increasing the output power of CW-LDs. The results also showed that the treatment location can be precisely positioned and that the treatment outcome can be monitored with real-time coregistration. In the evaluation of the correlation coefficients, blood leakage and the suspension of bleeding were observed. The results showed that the proposed OCT-guided microsurgery system could be a powerful tool for various clinical applications such as dermatology, ophthalmology, and liver and brain surgery.

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