To understand the pathophysiology and to develop a new diagnostic/therapeutic technique for ischemic stroke, we performed near-infrared diffuse reflectance imaging for a rat stroke model and examined whether an infarct core and periinfarct depolarization (PID) can be visualized by detecting light-scattering signal. After middle cerebral artery occlusion, light scattering increased in the ischemic core, around which a wave-like scattering change was generated and spread over the cortex repetitively, indicating occurrence of PIDs. The region with increased scattering in the ischemic core almost corresponded to the infarct area observed by TTC staining, suggesting that the scattering increase reflected cell morphological change associated with infarction.

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Recently, terrorism using explosive devices has been increasing, resulting in a large number of patients suffering from blastinduced traumatic brain injury (bTBI). However, the pathophysiology and mechanism of bTBI are not well understood and thus, methods for diagnosis and treatment of bTBI have not yet been established. We applied a laser-induced shock wave (LISW) to the rat brain, for which various real-time diagnoses were performed. We observed spreading depolarization, longlasting vasoconstriction and hypoxemia-oligemia in the brain even under the LISW conditions causing no changes in systemic physiological parameters and limited hemorrhage and contusion in the cortex.

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Wideband ultrasonic waves (referred to as photoacoustic waves) are induced as a result of transient thermoelastic expansion of biological tissues irradiated by a laser light. The magnitude of the photoacoustic (PA) waves is proportional to the local optical-energy deposition; hence, the waves divulge physiologically specific optical absorption contrasts. For visualizing the internal structure, PA image reconstruction which is a mathematical process with use of photoacoustic pressure is employed. Since image reconstruction has a fundamental impact on the image quality, various algorithms have been proposed. In this review article, we summarize reports regarding image reconstruction algorithms and introduce our approaches for the quantitative image reconstruction.

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The present investigation was to evaluate new bone formation of light emitting diode (LED) irradiation around the periosteum within the space formed by a polytetrafluoroethylene (PTFE) ring on the surface of rat calvaria periosteal elevation model. Experimental rats were divided into the following groups: control group (n=5), and LED irradiation group (n=5). LED group was irradiated with LED (850 nm) three times weekly for 1 and 3 months in at a dose of 8 J/cm² for 250 s. Analysis of new bone formation was performed in the area containing the inner cavity of the PTFE ring by micro-computed tomography (Micro-CT) and histology staining with hematoxylin and eosin. The bone mineral content (BMC), bone volume/tissue volume ratio (BV/TV), and bone mineral density (BMD) increased at 1 and 3 months after surgery in the control group and LED irradiation group. LED irradiation group increased BMC, and BV/TV in LED-treated new bone formation of the inner cavity of the PTFE ring compared with controls. In the LED irradiation group, the histological analyses confirmed newly formed bone around the PTFE ring. These results suggest that LED irradiation might be effective in new bone formation.

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Estimation error of the scattering coefficient in high absorption wavelength range about hemoglobin has been observed in optical property calculation of blood-rich tissues. In this study, relationship between accuracy of diffuse reflectance measurement in the integrating sphere and calculated scattering coefficient was evaluated with the optical property calculation system combined with an integrating sphere optics and inverse Monte Carlo method. Diffuse reflectance was measured by the integrating sphere with a small incident port diameter and optical properties were calculated. As a result, estimation error of scattering coefficient was improved by accurate measurement of diffuse reflectance. In the high absorption wavelength range, an accuracy of diffuse reflectance measurement effect on the calculated scattering coefficient.

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Recently access to the coronary arteries became available to laser coronary angioplasty because of a new technique utilizes a pulsed laser source and multifiber guided catheters. Potential advantages of excimer laser revascularisation include concomitant plaque debulking and thrombus removal and facilitation of adjunct stenting. Improved catheter design and improved technique and firmer indications have led to expansion of applications for laser coronary angioplasty. These include long lesions, ostial disease, saphenous veins, chronic total occlusions, moderately calcified lesions, thrombus rich lesions, failed balloon angioplasty and in stent restenosis. Laser coronary angioplasty represents a powerful tool to prepare the resistant lesions during conventional balloon angioplasty.

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Coagulation, thermal control, penetration in blood and laser-vein wall interaction are key factors for endovenous laser ablation. Although continuous-wave laser is popularly used, we have introduced a new concept of clear tip mode according to the micropulsation theory as pulse duration is limited in microsecond. Details of clear tip mode based on laser-tissue optics and initial clinical experience are discussed.

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The sympathetic nerve has vaso-motor action to give tension for the vascular smooth muscle of the very small artery. This contributes to blood pressure regulation and has a major role on a life support autonomously.However, the details are unknown which regional vaso-motor action each sympathetic nerve controls. We applied LASER Speckle Flow Meter (we abbreviate it to LSFG as follows) to thoracic sympathectomy of the local hidrosis patient and observed a change of the face / cervical part / in front of skin of chest blood flow, and we added some discussion.

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In recent years, much attention has been paid to treat cardiovascular diseases by laser techniques. That is, 1) Transmyocardial laser revascularization (TMLR) for end-stage of ischemic heart disease, 2) Laser vascular anastomosis, 3) Laser vascular angioplasty, these three categories are documented as follows. We have each performed experimentally and done clinically well, because of good experimental results. Consequently, feasibility of endovascular laser intervention could be recognized for the treatment of peripheral arterial diseases.

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