Object. Pulsed water jet surgical instrumentation is intended to achieve both maximal lesion resection and functional maintenance through preservation of fine vessels and minimal surrounding damage. On the other hands, avoidance of splash is critical problem to exclude the potential occurrence of dissemination. The present study evaluated the mechanism of splash and investigated the method to control it.Methods. This system consisted of a pump chamber driven by a piezo actuator, a stainless steel tube, and a nozzle. The water was supplied at 4 ml/min. The relationship between input voltage, suction pressure, distance between nozzle and the target, material property of fluid and the amount of splash. The amount of splash was quantitatively evaluated using imaging software and high speed camera. Results. Input voltage, distance, and additional fluid supply significantly decreased the amount of splash. Presence of water at the ejection site was suggested to be an important factor.

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Object. Pulsed water jet surgical instrumentation is intended to achieve both maximal lesion resection and functional maintenance through preservation of fine vessels and minimal surrounding damage. On the other hands, improving usability and avoiding obstruction of suction system is critical. The present study evaluated the mechanism of suction obstruction and investigated the method to control it.Methods. This system consisted of a pump chamber driven by a piezo actuator, a stainless steel tube, and a nozzle. The water was supplied at 4 ml/min at energy of 20V. The relationship between additional water supply (0-25 ml/min), internal diameter of suction tube, suction pressure (10-80 kPa), material property of fluid and the frequency of obstruction using brain phantom. Visualization and pressure measurement were also performed to elucidate the mechanism of obstruction. Results. Additional water supply, suction pressure, internal diameter, and material property of fluid significantly related with the frequency of obstruction.

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Object. The purpose of present study is to report the safety and efficacy of piezo actuator-driven pulsed water jet (ADPJ) system in neurosurgery and spinal cord surgery. Methods. The ADPJ system have been used as a part of standard procedure for brain and spinal cord pathologies after approval from internal review board of Tohoku University Hospital. Results. The system have been used in 5 malignant glioma, 6 meningioma, 1 callosotomy for intractable epilepsy, 1 cerebrovascular disease, and 5 spinal cord tumor. There was no complication related to the use of the system. Tissue could be dissected under preservation of fine arteries (diameter 200 microns). The present power was not enough for certain pathologies, especially for hard lesions.Conclusion. Although additional effort to enhance efficacy is necessary, present study indicated that the ADPJ have possibility to become novel surgical tools to assist maximal lesion removal and preserving postoperative function.

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BACKGROUND Waterjet dissection has broad application in neurosurgery. It enables precise dissection of gyri or intracranial tumors with sparing adjacent tissue and vessels. OBJECTIVE: To evaluate feasibility of waterjet in dissecting the spinal cord.METHODS: Waterjet was applied to dissect posterior median sulcus of anesthetized swine spinal cords. Waterjets were delivered in different strengths and various durations. In 4 separate swine, somatosensory evoked potentials were simultaneously recorded during dissections. Histological analyses were performed for lesion measurements and evaluating tissue sparing.RESULTS: Increased strength and exposure time of waterjet led deeper and wider dissections of the spinal cord. Light microscopy demonstrated minimal tissue damages along the dissected fissures. During the dissection with 10 volts for 30 seconds, responses of the somatosensory evoked potentials were maintained.CONCLUSION: Waterjet is feasible and reliable option in dissecting the spinal cord. It could possibly achieve both spinal cord dissection and functional preservation.

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In this study, the handheld combining treatment system was fabricated for the increasing in a manipulating performance and was evaluated. The system consisted of Peltier device, an acrylic pipe with coolant and a stabilized DC power supply. In the fabrication of the system, Peltier device with heat-sink was fixed to an acrylic pipe as a hand piece. In the evaluation of the system performance, temperatures of the operation side and the coolant were measured at nine conditions changed the current supply to Peltier element in no-load running with water as a coolant (n=3). The minimum temperature of the operating side reached to -7.8 degrees C at three conditions and the 2.3A of current condition was lowest temperature at 5 minutes from the measuring start in the three conditions. In evaluation test of temperature cycle performance, the temperature of the operation side continually changed on the freezing and heating process.

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We have reported that low-energy extracorporeal shock wave (SW) therapy improves cardiac function in a pig model of chronic myocardial ischemia by up-regulating vascular endothelial growth factor and enhancing angiogenesis. We have also conducted a series of clinical studies in patients with refractory angina pectoris without indication of PCI or CABG. Low-energy SWs were applied from the body surface to ischemic myocardium. In the first open study, the SW therapy significantly improved symptoms and myocardial perfusion. In the second double-blind and placebo-controlled study, symptoms and cardiac function were significantly improved by the SW therapy but not by placebo therapy. No adverse effects were noted. We also demonstrated that the SW therapy significantly improved symptoms, walking ability, and peripheral perfusion in patients with peripheral arterial disease and intermittent claudication. These results suggest that the low-energy SW therapy is promising, non-invasive and effective regenerative option for wide a range of cardiovascular disorders.

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We studied the dependence of immediate myocardial cell response on irradiance and photosensitizer concentration by an extracellular photosensitization reaction. We have proposed a new methodology for tachyarrhythmia treatment using the extracellular photosensitization reaction. Immediate cell response is needed in the tachyarrhythmia treatment since electrical physiological diagnosis is performed during the operation to judge the treatment effect. Intracellular Ca²⁺ during and after the reaction was measured using a confocal microscope and Fluo-4 AM as Ca²⁺ dye. The photosensitizer concentration, irradiance, and radiant exposure were varied 10-30 μg/ml, 30-293 mW/cm², and 10-40 J/cm², respectively. We found that the necrosis occurrence timing after the laser irradiation beginning was decreased with the photosensitizer concentration and irradiance increasing. The minimum necrosis occurrence timing was 209 s with 30 μg/ml in photosensitizer concentration and 293 mW/cm² in irradiance.

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We studied the drug delivery methodology on a vascular wall with a heating to improve drug delivery performance. The drug delivery has been used for hyperplasia suppression such as the drug eluting stent. We think thermal denature of vascular collagen might lengthen drug penetration depth to the media because of collagen structure change. The drug concentration and penetration depth in vascular were measured by a fluorescent microscope after 15 s of immersing vascular pieces in heated 3.5 μg/ml Rhodamine B solution. The heating temperature was set to 50-70 and 37°C for control. The drug concentration and penetration depth increased with heating temperature increasing. The drug concentration was 10-10⁴ times higher than the control. The penetration depth was 2-9 times longer than the control. We found possibility of drug delivery performance improvement by the means of thermal denatured collagen in the vascular wall.

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Many orthoses and power assisting devices for the people with muscle weakness are developed in Japan. However, since these devices need motor or compressor and consist of hard parts, there is problem that it is heavy, large and difficult to follow a flexible motion of human. If the small device which can follow a flexible motion of human and consists of soft parts could be developed, we thought that this problem was solvable. Then, by applying the EAM (Electro Attractive Material) which is the functional material of the shape of a sheet and was developed by us, we developed the sheet type EAM brake device which can control brake force by applying voltage and is thin and flexible. This brake device is a device in which braking force exerting is possible, even if this is bent.

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The lower extremity orthosis is used, to assist people who have the gait disturbance by injury or cerebral apoplexy or muscle weakness. However, there are some problems that the existing lower extremity orthosis has the function of only relieving the load or only fixing the joint of a leg and is difficult to bend the knees after fixing. Then, to solve these problems, by applying the EAM (Electro Attractive Material) which is the sheet type of functional material and was developed by us, we developed the linear EAM brake device which can control shear resistance generated in linear motion by applying voltage. Furthermore, we developed new EAM brake device which connected two brake devices in parallel using toothed belt and pulley. And this new brake device is the device for the application to the new lower extremity orthosis which can synchronize the brake device to bending and stretching of leg.

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Number of deaf of Japan is 343,000 people. There is need through interpreter if healthy people and deaf to communicate. However, number of interpreters is clearly insufficient for deaf. Therefore it is aimed for construction of sign language automatic recognition system (SLARS) to be able to take the communication without interpreter in this study. We built recognition program of fingerspelling that became first stage of SLARS. The system was calculated thumb, number fingertip, wrist orientation, circularity, Feret's diameter ratio, area ratio as features from video data of fingerspelling input by Kinect for windows sensors. We construct neural network (NN) using obtained six features and evaluated for the system by fingerspelling recognition rate. As a result, fingerspelling exceeding 80% recognition rate as compared with NN by four features were performed as pre-experiment was increased to 28 characters of 13 characters, and improved 74.0% from 36.6% overall recognition rate.

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We developed an algorithm of a reversible structure converted a plane to a solid in a moment by pulling two endpoints. The proposed method has an advantage to make a solid such as sphere from a material such as sheet, while it seems difficult it generally. The proposed structure can be used in laparoscopic surgery which has been used widely because the burden on patient is light. Laparoscopic surgery has a disadvantage that the view is small for surgeon. We can insert the proposed structure as plane mode in body and convert plane to solid in order to expand space for operation. The procedure requires little time and the usage has flexibility.

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It was reported the possibility to improve chronic inflammatory diseases and ischemic diseases by angiogenic or regenerative activity inducted by low-power shock wave. The purpose of present study was to evaluate the effect of shock wave on the liver function and the extent of fibrosis in the rat liver cirrhosis. Rats aged 7 weeks were treated with carbon tetrachloride intraperitoneal administration to create rat liver cirrhosis model. Shock wave (1000 impulses, 0.25 mJ/mm², 4Hz) was applied to the liver (SW); the controls were left untreated (C). Four days after irradiation, serum AST and T-Bil levels were significantly low in the SW group (AST: SW; 94.5±19.6 IU/L, C; 152.9±45.7 IU/L, T-Bil: SW; 3.1± 0.18 mg/dl, C; 3.94±0.44 mg/dl). Extent of liver fibrosis is tends to be reduced in the SW group pathologically. It may be possible to improve the liver function and fibrosis of the cirrhotic liver using shock wave therapy.

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Background: We have previously demonstrated that extracorporeal low-energy shock wave (SW) therapy ameliorates left ventricular (LV) remodeling through enhanced angiogenesis after acute myocardial infarction (AMI) in pigs in vivo. However, it is unclear whether the SW therapy also exerts anti-inflammatory effects on AMI.Methods and results: After AMI was created by coronary ligation, rats were randomly assigned to the 2 groups with or without the SW therapy (1, 3 and 5 days after AMI). The SW therapy ameliorated LV remodeling and fibrosis at 4 weeks after AMI. The SW therapy suppressed the infiltration of neutrophils and macrophages early after AMI, in addition to angiogenesis. The SW therapy also enhanced the expression of eNOS and suppressed the infiltration of TGF-β1-positive cells and pro-inflammatory cytokines. Conclusions: These results suggest that the low-energy SW therapy exerts beneficial effects on LV remodeling after AMI through anti-inflammatory effects in addition to its angiogenic effects.

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We have shown that electrical vagal stimulation (VS) markedly prevents cardiac remodeling and improves long-term survival in post-myocardial infarction (MI) rats survived for 2 weeks. It is well known that death within 2 weeks is mainly caused by lethal arrhythmia. We, therefore, started VS from an early stage after MI and examined its effects. One hour after left coronary artery ligation, VS or sham stimulation (SS) was started and continued for 4 weeks. The impact of VS was evaluated by deaths, echocardiography, cardiac catheterization, neurohumoral states and histological examination. VS significantly suppressed mortality within 24 hours (7% vs. 39%, p=0.02) and decreased heart rate (294±36 vs. 328±9 bpm, p=0.03). VS significantly prevented the progression of ventricular remodeling and improved indices of cardiac function. It is concluded that VS from an early phase of MI markedly suppressed arrhythmic death within 24 hours and prevented cardiac remodeling and dysfunction after acute MI.

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Although VNS benefits for heart failure, up titrations are limited in 72 % of human subject because of respiratory side effects. Since vagal nerves are connected to the respiratory center in brainstem, VNS is possible to change respiratory rhythms. In this study, we investigated how the frequency differences in VNS impact on respiration. In Sprague-Dawley rats (N=4), we changed the stimulus frequencies (5, 10, 20, and 50 Hz) and amplitude of VNS (0-8 V). In low frequencies (5 and 10 Hz), VNS slightly inhibited respiration with stimulus amplitudes. Maximum inhibition of minute ventilation was -18.4 ± 0.1 % in 5 Hz and -47.1 ± 2.7 % in 10 Hz. While in high frequencies (20 and 50 Hz), VNS induced apnea above 2-4 V. In conclusion, high stimulus frequency induced remarkable respiratory inhibition and apnea. It is negligible effect to titrate VNS.

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Background: Although VNS is known to have an anti-infarct effect, the technical difficulty associated with VNS precludes its application under clinical settings of AMI. We developed a novel technique where we stimulate the vagal system transvenously and evaluated how the VNS affects the infarction size and cardiac function in the long term.Method: We ligated the left anterior descending coronary artery for 3 hours, then reperfused. For transvenous VNS, we performed the field electrical stimulation in the superior vena cava. One month after the ischemia-reperfusion, we compared the infarct size and cardiac function with/without VNS. Results: Transvenous VNS significantly decreased the infarction size by more than 80% (1.1±1.2 vs. 7.8±1.2cm2, p<0.05), doubled left ventricular systolic elastance (6.5±1.7 vs. 13.2±0.6 mmHg/ml, p<0.05), and decreased NT-pro BNP (3667±1637 vs. 843±256 pmol/ml, p<0.05).Conclusion: Transvenous VNS in AMI markedly reduces the infarct size and improves cardiac function in the chronic phase.

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[Background] Baroreflex is known as a quick and strong negative feedback system to stabilize arterial pressure through modulating the autonomic nervous system. In the clinical settings such as aortic dissection and hypertensive emergency, cardiovascular drugs often fail to lower arterial pressure to the target level. So a new therapeutic strategy is warranted. [Method] In an anesthetized dog preparation, we inserted an electrode catheter into the right carotid artery and positioned at the carotid sinus level. Then we stimulated the carotid sinus while measuring the arterial pressure. [Results] Stimulation of carotid sinus decreased arterial pressure from 129 mmHg to 76 mmHg and the steady state was reached within 1 minute. [Conclusion] Intravascular electrical stimulation of carotid sinus activated the baroreflex and successfully decreased the arterial pressure. This system would be a novel therapeutic modality to treat patients who require immediate control of arterial pressure.

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Soft-heating method is one type of hyperthermia that necrotizes malignant tumors in cancer treatment by means of heat generated by a ferromagnetic material. The magnetic permeability of ferromagnetic particle decreases immediately when its temperature increases over the Curie point (43°C). Therefore, we can concurrently use the ferromagnetic particles as a thermal probe for wireless temperature measurement during hyperthermia treatment. A challenge remains when dealing with body movement artifact as the relative position between the detection coil and the material is fluctuated by breathing or beating of the heart. As a result, the accuracy of temperature detection decreases. In this report we suggest and verify the validity of the new inspection system for the body movement artifact removal by regularly circling a unit of the magnetic field supply coil and the detection coil around the upper surface of the tumor region.

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Hyperthermia is a cancer therapy by using thermosensitivity of cancer cells. We previously developed a wireless temperature measurement system for Hyperthermia using Ferromagnetic Implant with Low Curie Temperature (FILCT). However, when initial bias, caused by the position and posture of the detection coil, is large enough, change of feeble voltage in the detection coil cannot detect. In this report, therefore, we suggest a method for reducing the initial bias by analog signal superimposition. A reverse phase voltage of an additional coil is added to the voltage of the original detection coil, as a result the initial bias value is by 0V. Furthermore, as the reverse phase voltage changes concurrently, the influence caused by the fluctuation in applied magnetic field can be also reduced. We verified our analog signal superimposition method and confirmed its validity by physical experiments.

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The essential requirements for implants utilized in magnetic hyperthermia are high calorific power in alternating magnetic field, high corrosion resistance in body. In addition, the fabrication process is require simple and stable with low cost from a practical application perspective. In this research, we investigate calorific property of micro implants dispersed ferromagnetic particles. The implants was molded into beads needle and capsule by simple mechanical processing. The amount of heat generation of ferromagnetic particles was increased with increasing magnetic hysteresis loss by mechanical milling treatment which is able to pulverize and provide strong strain. Temperature rising of the implants in chicken meat as a mock tumor and thermal alteration of surrounding cells will be reported.

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Artificial heart needs power supply from outside of the body at the present time. Therefore, the patients have a risk of bacterial infection. Contactless power transmission by electromagnetic is one solution, but is hard to be applied to practical use due to a size and an embedded part of the coil for the transmission. In this study, we made flexible coils out of flexible board and studied the possibility of implantation into side chest, the part mostly unaffected by a patient's motion. The coil is air-core, 90mm in diameter, has 35 turns, and width and an interval of wire is 4mm. To search influence of curving coils on the transmission, we curved the coils into 60mm at the curvature radius and changed distance a between primary and secondary coils simultaneously. As a result, the flat and curving coil magnetic coupling efficiency is 0.99, 0.97 (a=0), 0.84, 0.81 (a=1.6), 0.48, 0.51(a=11.6).

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Artificial organs using shape memory (SMA) fibers have possibilities to achieve small size and simple control. However, there was a problem of the instant heavy load; we proposed an efficient transcutaneous energy transmission system with internal energy storage circuit for SMA fibered devices.In this system, the internal storage capacitor was charged slowly while the fibers are turned off and discharge the energy when the fibers are turned on. We examined the effect of the system. Firstly we changed capacitance from 500uF to 34100uF. Secondly we changed the input current limitation. With largest capacitance, the device could be driven,however with smallest capacitance devece did not worked.With the cuurent limitattion,the input current was reduced to 0.5A. It was found that the size and maximum output of the TETS would able to be reduced and drive the SMA fibers efficiently.

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Ultrasound-guided needle placement such as radiofrequency ablation has been widely used for safe and low-invasive procedures. Meanwhile, an ultrasound probe has to be placed for monitoring tumor and needle positions. Therefore, we have developed a probe scanning robot using pneumatic actuators to automatically visualize a needle in 2D echogram plane. However, it was difficult that the system with a conventional 2D probe follows both the target tumor and the needle. Thus, focusing on xPlane imaging of a 3D probe, which provides two cross-sectional echograms in real-time, we developed an improved system to compensate three-dimensional motion of a target by the visual feedback.

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We developed a transformable endoscopic hood using hydraulic actuators for endoscopic surgery. This device can be attached onto the tip of an endoscope to assist physicians operating endoscopic submucosal dissection (ESD), which is an operation for removing lesions in digestive organs. In this paper, we designed and fabricated a transformable hood using hydraulic actuators. The hydraulic actuator consists of biocompatible parylene membrane and stainless steel coil. By changing the pressure applied on the hood, the tip radius of the hood changes, and the radius ranged from 4.5 mm to 11.5 mm. When the tip diameter was fixed to 16 mm, the maximum force generated by the hood was 123 mN.

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A bending mechanism of conventional endoscope bends by traction of wires from outside the human body. A shaft structure of endoscope is relatively complex to avoid buckling by wire traction force. In this study, thin diameter active bending electric endoscope was developed using shape memory alloy (SMA) wire. The SMA wires are driven by Joule heat provided electrical current. Therefore active bending device using SMA wire makes it possible to simplify the bending mechanism and the shaft structure. Fabricated device is mounted commercial CMOS imager, three LEDs and bending mechanism. This device accomplishes multi direction bending and the curvature radius is 40 mm at 300 mA.

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We studied the Monte-Carlo model based on the measurement of the irradiance distribution of 663 nm light in porcine myocardium emitted from photodynamic ablation catheters to investigate treatment region by a photodynamic reaction. Since adjacent organs are behind the myocardium, irradiation conditions not to injure the organs are needed. Irradiance distribution in the porcine left ventricle 3-4 hours passed after the removal was measured at 1-5 mm in vertical direction, at ±5 mm in horizontal direction by the light-receiving fiber (core diameter:200 μm, NA:0.53) and the catheters. Monte-Carlo model was adjusted under the constant absorption coefficient based on the measurement. The error of the exponent by exponential approximation associated with vertical and horizontal distance variation was less than 5%. The estimated treatment region approximately matched to the previous result of a dog experiment by the Monte-Carlo model and a published cell lethality measurement data.

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Aim:We aimed to construct a method of finite element analysis (FEA) on a coronary stent deployed in cyclically-bended artery.Method:A CoCr alloy stent was analyzed using ADINA8.9 in three steps: (1) crimp the stent onto a balloon, (2) deploy the stent in the artery model by balloon inflation, (3) bend the artery model in the angle range from 105 deg to 125 deg. Finally, the fatigue safety factor (FSF) was calculated by stress amplitude and mean stress.Result and Discussion:We found that the FSF is higher at the links and crowns connected to links at the bended region. The portion of stent fracture observed in the durability tests was coincident with the higher FSF region. Conclusion:We constructed the FEA method of the coronary stent in the successive processes of crimping onto the balloon, deploying and bending in the artery model.

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Normally since a guide wire, which diameter is 0.4 mm in minimum, is needed to induce a catheter, there is limit in adaptation area. Therefore, there is no way to induce a catheter, which diameter is less than the wire. In this study, we consider the induction of the thin catheter using acoustic radiation force instead of the wire. First we have estimated the force acting on the catheter by cantilever theory. Using the result, we have confirmed that the catheter (φ 0.2 mm, PFA) was induced to the desired area using ultrasound on multiple bifurcations as shown in the figure. From the result, it is suggested that thin catheter induction using ultrasound is possible to clinical applications.

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Recently, drug delivery to a brain tissue has extensively been investigated, but a method for real-time, in vivo monitoring of the drug has not been established. We have been applying photoacoustic (PA) imaging method to visualize both the blood vessels and drug in a brain. In this study, we performed label-free in vivo imaging of the cerebral blood vessels in a rat by using an originally developed compact PA imaging system (Fig.1). By compensating the attenuation of excitation light in the tissue, blood vessels with diameters larger than 50 μm were visualized in the depth range up to 2 mm (Fig.2).

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Multichannel functional near-infrared spectroscopy (fNIRS) has been increasingly used for exploring functional activation in human cerebral cortex. To avoid false negative detections of cerebral activation, however, a high-density measurement with appreciable numbers of NIRS optodes is indispensable. This leads an elongated experiment time and subjects' affliction. To reduce the number of optodes required for multichannel high-density measurement, we developed a new optode whose one end was bifurcated. The bifurcated ends were separately connected to the source and detector equipped in the main NIRS system. Each optode was used as the source- and detector-optode by temporally switching with system. Optodes were hexagonally arranged with a lattice pitch of 30 mm. The distance between the measurement channels (middle points of lattices) was 15 mm in this arrangement. This newly designed method achieved a high-density fNIRS measurement at the same region with fewer (almost half) optodes than the conventional double-density optode arrangement requires.

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In brain functional measurement by near-infrared spectroscopy, it is important to improve the measurement accuracy and to expand the measurement region. Expansion of the measurement region is effective for analyzing the brain functional connectivity. Further, it is necessary to detect a signal for correcting the disturbance and skin blood flow change for improvement of the measurement accuracy. Especially, for the purpose of cancellation of the disturbance, multi-channel signals are required and an increase in the system size has become an issue. In this study, we propose a method of separating multiple signals using digital encoding technology and apply it to our cancellation method. The signal processing method and the cancellation method were verified by computer simulation and phantom measurements.

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Selective detection of peripheral nerve during surgery is a key technique to avoid neural disturbance following surgery as an aspect of realizing better functional outcome. In general procedure of surgery, peripheral nerve is identified by human eye or under white light imaging. However, functional deficits due to neural injury following surgery were reported because of invisible of thin but important peripheral nerves. To obtain better functional outcome, the intraoperative detection of peripheral nerves including thin peripheral nerves that is important for sustained functions is desired. In this study, we investigated the feasibility of Raman spectroscopy in selective detection of peripheral nerves against adjacent tissues. We analyzed Raman spectrum of peripheral nerves and adjacent tissues of rats and human periprostatic tissues, and revealed spectral features of peripheral nerves. Moreover, selective detection of peripheral nerves was demonstrated by multivariate Raman spectral analysis of peripheral nerves and its adjacent tissues in ex vivo.

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In the conventional time-resolved measurement, an analytical solution of the diffusion equation is fit to the experimentally measured time-resolved reflectance. The diffusion approximation does not hold for the time-resolved reflectance measured with a small source-detector spacing. In this study, time-resolved reflectance was calculated by a Monte Carlo simulation to measure the optical properties of the cortical tissue of rats in vivo. The optical property measurement from the time-resolved reflectance measured with a small source-detector spacing using the simulated data calculated by the anisotropy factor of 0.9 was able to reduce errors in comparison with that calculated under the diffusion approximation. The experimentally measured time-resolved reflectance of the rat cortex was compared to those calculated by Monte Carlo simulation convoluted with the instrument response function to determine the optical properties.

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Laser angioplasty is suitable for difficult-to-treat lesions. However, conventional excimer laser (wavelength: 308 nm) has a risk of injuring normal vessels by erroneous or excess irradiations. Atherosclerotic plaques mainly consist of cholesteryl esters. Radiation at a wavelength of 5.75 μm is strongly absorbed in C=O stretching vibration mode of cholesteryl esters. Our previous study achieved to make cutting differences between a rabbit atherosclerotic plaque and a normal vessel by a compact quantum cascade laser (QCL) in the 5.7 μm wavelength range. However, wide thermal damage was occurred. The QCL worked as a pseudo-continuous wave laser because the pulse interval of QCL was shorter the thermal relaxation time of the samples. Therefore, we tried irradiation of pulses at intervals (macro pulse irradiation) and compared with conventional continuous irradiation. As a result, there was no significant difference in thermal damage width. Therefore, more improvement of output power and pulse structure is required.

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Frequent maintenance for the arteriovenous fistula for hemodialysis is essential, since it often causes stenosis and occlusion. We have developed a simple and noninvasive technique to obtain transillumination images of the arteriovenous fistula using near-infrared light. The image of the blood vessel is significantly blurred due to the strong scattering in the body tissue. To solve this problem, we applied the decovolution technique with a point spread function. In the experiment using the human forearm phantom, we attempted to detect the diameter change of the blood-filled tube. As a result, we could detect the diameter change with the spatial resolution of 1 mm at 1 mm depth from the body surface. This suggests the possibility that we can detect the temporal change of the arteriovenous fistula and that this enables us the daily monitoring of its condition.

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In order to study condition of arrhythmia treatment by a photosensitization reaction, we developed in vitro cardiomyocyte electrical conduction (EC) line to study EC block by photosensitization reaction. Cardiomyocytes were cultivated on 10 mmφ cover glasses. Cultivated and non-cultivated width were 60 and 300 μm, respectively; for 3-4 days, 37C°, 5% CO₂. Cardiomyocyte cultivate concentration were 2.0-8.0×10⁵ cells/ml. EC of cardiomyocite was measured by 5 μM Fluo-4 AM (Ca²⁺ probe) with a confocal microscope system. Frame rate of EM-CCD was 400 ms. Cadiomyocyte was cultivated in a confluent line by 4.0×10⁵ cells/ml. In 4 days cultivated 4.0×10⁵ cells/ml cardiomyocite line, 1 /s synchronized pulsation was measured as Fluo-4 AM intensity change. Cross correlation coefficient was about 0.8. This result indicated that cardiomyocyte EC was occurred.

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Raman spectroscopy is an optical technique that enables us to analyze pathological changes based on molecules without labeling. In the present study, we sought to examine Raman spectroscopic changes in rat myocardial infarction. Raman spectra were acquired from normal and infarcted myocardium through sequential stages of myocardial necrosis, granulation and fibrosis. The latent variable weights calculated by partial least squares-discriminant analysis showed information on the spectral differences among the types of tissues based on molecules. We conclude that Raman spectroscopy is applicable to label-free analysis of myocardial infarction.

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For transcutaneous imaging of arteriovenous fistula in dialysis treatment, we have developed a technique to improve the transillumination image. In this technique, we obtain an appropriate point spread function (PSF) using a fluorescent source implanted near the fistula inside the body. First, the reproducibility and the appropriateness of the measured PSF were verified using different shape of fluorescent source. Then the possibility to detect the diameter-change in blood vessel was confirmed using a known structure phantom. Finally, the applicability to animal tissue was verified in the experiment. Fig. 1 shows the improvement of the image of a blood-filled tube in chicken breast meat.

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We developed a nonlinear optical multimodal microscopy system for diagnostic tool of atherosclerosis. Nonlinear optical microscopy is based on the nonlinear optcal phenomena originated from optical properties of materials. It avoids the need for invasive dyes. In particular, coherent Raman scattering (CRS) techniques provide label-free detection due to the intrinsic vibrational signatures of the specific molecules. Therefore it offers a non-invasive imaging of lipid in atherosclerotic plaques. The second harmonic generation (SHG) is exclusively sensitive to noncentrosymmetric materials. Hence, it enables a label-free detection of collagen which is known to be unpredictably formed around the plaques. Therefore, CRS/SHG multimodal microscopy system is a potential tool for quantitative diagnosis of atherosclerosis.
In this study, we provided a histological assessment of abnormally produced collagen in aorta samples of mice, and our results indicated that the collagen had a correlation with the progression of lesion. Furthermore, we performed CRS/SHG imaging with the developed system.

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Optical coherence tomography (OCT) is a very useful technique to acquire high-resolution cross-sectional imaging under the skin surface in vivo. We have demonstrated dynamic analysis of the physiological function of eccrine sweat glands of human finger by OCT. We propose a novel method for extraction of the target eccrine sweat gland on the fingertip by use of the connected component extraction process and the adaptive threshold method, where the en-face OCT images are constructed by the SS-OCT. We confirm the spiral structure of the sweat gland from the 3D volume rendering of OCT images. Furthermore, we measure precisely the volume of one sweat gland and the diameter of the sudoriferous duct. There is a significant difference in the structure of the sweat gland between patients with palmo-planter hyperhidrosis and healthy subjects.

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In order to understand pathogenic mechanism of allergic dermatitis, it is important to find morphological changes of the internal structure of the skin by non-invasive imaging. We proposed temporal observation of internal skin tissue of guinea pigs induced allergic dermatitis by OCT. In the case of male animals, the affected part of the epidermis thickened immediately, and we observed microvessel in dermis. The epidermis thickened corresponding to passing of day. On the other hand, in the case of female animals, the degree of thickness was lower than that of male, and the difference of thickness among each day was not confirmed.In this research, we succeeded to evaluate the thickness of epidermis on allergic dermatitis quantitatively. It was suggested that OCT has important role for diagnosis of severity or follow up this disease.

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Optical coherence tomography using a swept light source (SS-OCT) offers the potential for high-speed data acquisition. SS-OCT reduces the quality degradation of in-vivo OCT images of moving artifacts caused by the movement of the body, and it also achieves rapid imaging with 3D-OCT. In order to achieve the high repetition rates, we have successfully developed a new light source incorporating the electro-optical deflector. The deflector is based on a KTa1-xNbxO3 (KTN) single crystal. The deflection effect of the KTN is caused by a non-uniform electric field generated by injected carriers, and it exhibits a fast response and a fairly large light deflection angle. In this study, we demonstrated a high-speed three dimensional OCT system based on a swept light source incorporating a KTN deflector with an A-scan rate of 400,000 lines/s. The further improvement of the current system performance can be expected.

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Recently, we have proposed two-photon absorption-induced photoacoustic microscopy (TP-PAM) to visualize deep tissues with high spatial resolution. Generally, photoacoustic imaging uses nanosecond pulse lasers which can easily achieve high pulse energy. However, the optimization of laser parameters is still insufficient to improve the generation efficiency of photoacoustic signals and signal-to-noise ratio. In this paper, we developed TP-PAM using a pulse-duration-variable ultrashort pulse laser (200fs - 7ps) and sub-nanosecond pulse laser (600ps). We investigated the pulse-duration dependence in the region of femtosecond to nanosecond and the energy dependence in the region of nanojoule to microjoule. As a result, we found that the generation efficiency of two-photon photoacoustic signals is improved with decreasing in pulse duration, while that of one-photon photoacoustic signals is kept constant. This means that the shorter pulse duration improves generation efficiency of two-photon photoacoustic signals and imaging contrast.

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Optical tweezers is a major technique to manipulate cells. 3D observation method of cell manipulation is required for the purpose of visualizing rotations and 3D position. However, this method is especially difficult because optical path of both optical tweezers and 3D observation will interfere. We developed a system to resolve the difficulty with using a variable-focus lens (VFL). We continuously acquire slice images having modified focal position and reconstruct them to get 3D image. The VFL changes focal position rapidly and is set at a position not to interfere the optical tweezers. We succeeded to get slice images in 30 fps and to reconstruct into 3D images in the experiment.

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Tissue optical properties are determined by the combination of an integrating sphere optical measurement and inverse Monte Carlo caluculation. However, the estimation error of scattering coefficients have been confirmed at a high absorption wavelength range with hemoglobin (Hb) containing samples. It is because that distributions of diffuse reflection lights are different between low and high absorption samples. The purpose of this study is to determine a high-precise scattering spectrum without the estimation error. The relationship between Hb concentrations and angular distributions of diffuse reflection lights, and effects of an incident port diameter on the estimation error were evaluated. In the low absorption wavelength at 664 nm, angular distributions were similar regardless of Hb concentrations. In the high absorption wavelength at 405 nm, diffuse reflection lights had biased angular distributions toward specular reflection direction as Hb concentrations increased. The estimation error was improved as incident port diameter became smaller.

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We have sought the possibility to suppress the scattering in trasillumination image by analyzing the beam wave propagation in a turbid medium. If incident light is homogeneous, the scattering effect is suppressed with a point spread function of a point light source using the negative image of the observation. We newly introduced this principle to the case with inhomogeneous light beam illumination. Fig. 1 shows the result of the experiment. It shows that the background scattering in homogeneity is effectively suppressed by the proposed technique.

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With the view toward the realization of optical CT imaging, we have developed the simultaneous estimation technique of scattering (μ'_s) and absorption (μ_a) distributions. The usefulness of the proposed technique was verified in experiment with three-layer-structure models. Fig. 1 shows an example of estimation result of μ_a distribution. The error was less than 20% in the range of μ'_s = 0.75 - 2 /mm. Fig. 2 shows the results of the comparison between the former and present techniques. We used to assume that μ'_s is homogeneous and known, a priori. With the proposed technique, the estimation error was reduced by 95%. Through these analyses, the usefulness of the proposed technique was verified.

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We measured brain blood flow in the sensory-motor areas during wrist extension with Trigger mode(T mode) TES and Power Assisted mode(PA mode) TES. Brain blood flow was measured by Near-Infra-Red Spectroscopy system(NIRS).The subjects were healthy eight male(21-23 ages). The data were analyzed using the software package NIRS-SPM. The blood flow was slightly increased in PA mode; but it was reduced in T mode. In PA mode, it was required continuously voluntary muscle contraction for the continuously electrical stimulation. In T mode, the contraction was needed only at the start of stimulation then passive muscle contraction continues which was evoked by stimulation, so blood flow was decreased.

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We have developed a technique to estimate the absorption coefficient (μ_a) distribution of turbid medium using the backscattered light, and verified its feasibility. For accurate estimation of μ_a, accurate scattering property (μ'_s) is essential. Here, we newly developed the simultaneous estimation technique for μ'_s and μ_a by attaching the diffuser plate with known μ'_s and μ_a. The validity of the proposed technique was verified in simulation. Fig. 1 shows an example of the μ_a estimation with former and new techniques. The accuracy was apparently improved. Fig. 2 shows the result of the error analysis of 20 cases with various μ'_s and μ_a. The estimation error was significantly suppressed.

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