Project

High-precision Diagnostic Devices

We are working on early detection, high accuracy and minimally invasive diagnostic approaches at the area’s core hospitals and advanced hospitals, by employing complex, high-precision diagnostic devices for early detection, featuring improved time and spatial high resolution thanks to advanced physical signal processing technology (such as ultrasound, acoustics, light, magnetic field and electrical field).

Research Representative
Hiroshi Kanai

Hiroshi Kanai, Graduate School of Engineering / Biomedical Engineering
Development of diagnostic devices using high-precision ultrasound echo

(1) Development of a Highly Sensitive Ultrasound-Based Diagnosis System for Visualization of Propagation of Myocardial Response to Electrical Excitation

For the realization of noninvasive and regional myocardial tissue characterization, in the present study, we attempted to elucidate the characteristics of the myocardial response to electrical excitation and its propagation by an ex vivo experiment using a rat left ventricular wall. To visualize such a propagation phenomenon, whose speed is up to several m/s, high-frame-rate ultrasound was used to measure the myocardial vibrations driven by electrical excitation at 72 points along the heart wall with 200 µm intervals at a frame rate of 3472 Hz. The propagation of myocardial vibration was visualized by estimating the delay time between vibration waveforms measured in the reference ultrasonic beam and each ultrasonic beam using the cross-correlation function between the vibration waveforms. From the estimated delay time, we visualized the propagation of myocardial vibration caused by electrical excitation. The propagation speed was estimated to be 2.5 m/s in the entire excised myocardium. It was also estimated to be 1.8 m/s in the middle of the heart wall and 2.2 m/s at the internal and external surfaces of the left ventricular wall. The results showed that the myocardial vibration driven by electrical excitation could be measured with high-frame-rate ultrasound. A new ultrasonic diagnosis system has been now developed so that these new-founded phenomena can be visualized in real time.

(2) Development of a Highly Sensitive Ultrasound-Based Diagnosis System for Red Blood Cell Aggregation

We developed a new method for assessment of the degree of red blood cell (RBC) aggregation by the scattering property of RBCs. In this method, the scattering property of RBCs is extracted from the power spectrum of RBC echoes normalized by that from the posterior wall of the vein. In an experimental study using a phantom, by use of the proposed method, the sizes of microspheres 5, 20 and 50 µm in diameter were estimated to be 4, 14 and 50 µm, respectively. In the in vivo experimental study, we compared the results between three healthy subjects and three diabetic patients. The averaged estimated scatterer diameters in healthy subjects at rest and during avascularization were 7 µm and 28 µm, respectively, while those in diabetic patients were 14 µm and 35 µm, respectively. These results show that the proposed method has high potential for clinical application to assess RBC aggregation.

Visiting Researcher
Yuji Kondo

Yuji Kondo, Graduate School of Engineering
Development of a Highly Sensitive Ultrasound-Based Diagnosis System for Measurement of Elasticity of Arterial Wall

It is effective to measure a blood vessel elasticity routinely to judge an arteriosclerotic risk. To that end, it is necessary to measure the vessel thickness following the vessel wall by a simple system with easily method. We developed algorithm to detect vessel wall effectively in real time and developed the special ultrasonic probe that can measure the blood vessel elasticity. The probe is connected to PC with USB and the special software installed in PC analyzes the ultrasound signal.

Researchers

Nobukazu Nakasato, Graduate School of Medicine
Wide band mapping of cerebral functions using room temperature magnetoencephalography
[from FY2012]

High frequency oscillations (HFOs) are measured for both epileptic activity and normal cortical function in human using scalp electroencephalography (EEG), intracranial EEG and superconducting quantum interference device (SQUID) based magnetoencephalography (MEG). Epilepsy-specific HFOs were clearly dominant during rapid-eye-movement (REM) sleep stage than in any different awake-sleep stages. Somatosensory and auditory HFOs can be visible clearly in intracranial EEG and moderately clearly in SQUID-MEG, but not visible in scalp EEG. Taking into consideration of various characteristic of tunnel magnetic resistance (TMR) based MEG system, HFOs can be one of the best application target of the upcoming new TMR-MEG system.

Kazuhiko Yanai, Graduate School of Medicine
Development of early diagnosis of cognitive dysfunction and cancer using molecular imaging
[from FY2012]

Molecular Imaging emerged in the early twenty-first century as a discipline at the intersection of molecular biology and in vivo imaging. It enables the visualization of the cellular function and the follow-up of the molecular process in living organisms without perturbing them. The multiple and numerous potentialities of this field are applicable to the diagnosis of neuropsychiatric diseases and cancer. This technique also contributes to improving the treatment of these disorders by optimizing the pre-clinical and clinical tests of new medication. They are also expected to have a major economic impact due to earlier and more precise diagnosis and application to drug development. Recently, molecular imaging is proving very valuable in the early and differential diagnosis of Alzheimer's disease and cancer. We have examined amyloid, -synuclein and tau deposits in the brain of patients with neurodegenerative disease using an automated synthesis unit. In addition, we have developed a new method for macromolecules labelling with a PET radionuclide 18F using a cell-free translation system. These techniques are useful for the early diagnosis of neurodegenerative diseases and cancer.

Yoshifumi SAIJO, Graduate School of Biomedical Engineering
High Resolution Photoacoustic Biomedical Imaging   [from FY2013]

Photoacoustic (PA) method which is based on PA phenomenon may realize high resolution and deep penetration imaging of the biological tissues. When a nano-second pulsed laser is illuminated to the biological tissue, light energy is absorbed. Local temperature rise leads to a thermal-elastic expansion and the generation of a pressure wave which is called as PA signal. The PA signal is then detected by ultrasonic transducer or hydrophone. Thus, PA signal depends on absorption coefficient of the tissues and the wavelength of the laser. The amplitude of the PA signal is expressed by the absorption coefficient and the tissue elasticity. Therefore, PA imaging provides not only the morphology or structure but also the information on the color and elasticity of the tissue beneath the opaque layers. In the present study, we develop a PA imaging system using a semiconductor laser for visualization of biological tissue for further development of diagnostic device.

Shigeru Shoji, Tohoku University Hospital
Development of lateral canal finding apparatus which treat the dental chronic pain   [from FY2014]

Aim: The aim of this study was to establish the method to find the position of a lateralcanal based on the value of two electric current readings in vitro to treat the dental chronic pain.
Methodology: We made the artificial lateral canal model in a transparent epoxy resin block. We measured; one apical foramen without a lateral canal (case A), no apical foramen with a lateral canal (case B) and one apical foramen with a lateral canal (case C). We measured the electric current (500 and 2000 Hz) between a top of reamer and apical foramen.
Result: In case A, the line of indicated value (I.V) was a rising diagonal stroke from bottom to top right. In case B, the line of I.V had one convex slope. And in case C, the line of I.V had one convex and one concave slope. We analyzed the relationship between the position of lateral canal and the x value of local maximum value using Mann-Whitney’s U test. We found the same population.
Conclusion: By detecting x value of local maximum value of I.V, we will be able to determine the position of lateral canal without Dental CT clinically.

Knowledge based Medical Device Cluster / Miyagi Area ICR

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