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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

Top view of 3D OCT images and depth-encoded projection view of OCT angiography recorded (a,e) before blood leakage was induced by a needle, (b,f) during blood leakage, (c,g) after exposure to 532-nm laser for 5 s, and (d,h) after exposure to 532-nm laser for 10 s. The white arrows represent the region of leaked blood.
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f3: Top view of 3D OCT images and depth-encoded projection view of OCT angiography recorded (a,e) before blood leakage was induced by a needle, (b,f) during blood leakage, (c,g) after exposure to 532-nm laser for 5 s, and (d,h) after exposure to 532-nm laser for 10 s. The white arrows represent the region of leaked blood.

Mentions: Moreover, to observe the blood leakage and obtain angiography in three dimensions, the ear skins of the mice were scanned with OCT to obtain 3D microstructural images, and the cross-correlation coefficients of the OCT images were estimated to acquire the angiography of the mouse ears and observe the blood leakage. Here, the moving particles, such as leaking blood cells from the vessels and moving blood cells in vessels, cause larger variations in backscattered intensities between two OCT images captured at the same location, resulting in low correlation. In contrast, the static particles or static tissue structures correspond to higher correlation between OCT images obtained at the same location. Therefore, the leaking blood cells and the moving blood cells can be visualized by extracting the regions of low correlation. To remove the contribution from the static particles, the regions of high correlation are rejected to acquire angiography and observe blood leakage. Again, the same procedures were repeated. Figure 3 shows the top view of the 3D OCT images and the depth-encoded projection view of the OCT angiography: (a, e) before blood leakage, (b, f) during blood leakage induced with a needle, (c, g) after exposure to the 532-nm laser for 5 s, and (d, h) after exposure to the 532-nm laser for 10 s. Before inducing blood leakage, no morphological change can be found in Fig. 3(a) and only angiography can be observed in Fig. 3(e). Then, the blood leaked from the vessel due to the punch of a needle. In Fig. 3(b), a ball shape indicated by the white arrow represents the leaking blood drop and then, the correlation coefficients were also estimated as shown in Fig. 3(f). In Fig. 3(f), the red spot indicated by the white arrow shows the leaking blood drop, corresponding to the lower correlation. Then, the laser beam of 532-nm laser was accurately controlled to focus on the leaking blood. After the 5-s laser exposure, the cross-correlation coefficients of the exposure area indicated by the white arrow in Fig. 3(g) became larger than those for Fig. 3(f). This was the result of the bleeding being suspended owing to blood coagulation. Moreover, the black area in Fig. 3(h) decreased when the exposure time was increased because of blood clotting. Additionally, it can be found from Fig. 3(d) that the skin surface became tightened. Therefore, the results showed that the OCT-guided laser microsurgery system enables accurate control of the treatment location to avoid extra damage and to monitor the treatment outcome with real-time coregistration.


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)

Top view of 3D OCT images and depth-encoded projection view of OCT angiography recorded (a,e) before blood leakage was induced by a needle, (b,f) during blood leakage, (c,g) after exposure to 532-nm laser for 5 s, and (d,h) after exposure to 532-nm laser for 10 s. The white arrows represent the region of leaked blood.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Top view of 3D OCT images and depth-encoded projection view of OCT angiography recorded (a,e) before blood leakage was induced by a needle, (b,f) during blood leakage, (c,g) after exposure to 532-nm laser for 5 s, and (d,h) after exposure to 532-nm laser for 10 s. The white arrows represent the region of leaked blood.
Mentions: Moreover, to observe the blood leakage and obtain angiography in three dimensions, the ear skins of the mice were scanned with OCT to obtain 3D microstructural images, and the cross-correlation coefficients of the OCT images were estimated to acquire the angiography of the mouse ears and observe the blood leakage. Here, the moving particles, such as leaking blood cells from the vessels and moving blood cells in vessels, cause larger variations in backscattered intensities between two OCT images captured at the same location, resulting in low correlation. In contrast, the static particles or static tissue structures correspond to higher correlation between OCT images obtained at the same location. Therefore, the leaking blood cells and the moving blood cells can be visualized by extracting the regions of low correlation. To remove the contribution from the static particles, the regions of high correlation are rejected to acquire angiography and observe blood leakage. Again, the same procedures were repeated. Figure 3 shows the top view of the 3D OCT images and the depth-encoded projection view of the OCT angiography: (a, e) before blood leakage, (b, f) during blood leakage induced with a needle, (c, g) after exposure to the 532-nm laser for 5 s, and (d, h) after exposure to the 532-nm laser for 10 s. Before inducing blood leakage, no morphological change can be found in Fig. 3(a) and only angiography can be observed in Fig. 3(e). Then, the blood leaked from the vessel due to the punch of a needle. In Fig. 3(b), a ball shape indicated by the white arrow represents the leaking blood drop and then, the correlation coefficients were also estimated as shown in Fig. 3(f). In Fig. 3(f), the red spot indicated by the white arrow shows the leaking blood drop, corresponding to the lower correlation. Then, the laser beam of 532-nm laser was accurately controlled to focus on the leaking blood. After the 5-s laser exposure, the cross-correlation coefficients of the exposure area indicated by the white arrow in Fig. 3(g) became larger than those for Fig. 3(f). This was the result of the bleeding being suspended owing to blood coagulation. Moreover, the black area in Fig. 3(h) decreased when the exposure time was increased because of blood clotting. Additionally, it can be found from Fig. 3(d) that the skin surface became tightened. Therefore, the results showed that the OCT-guided laser microsurgery system enables accurate control of the treatment location to avoid extra damage and to monitor the treatment outcome with real-time coregistration.

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