This paper describes the fundamentals of MRI (magnetic resonance imaging) and current related technologies. MRI measures the chemical structure distributed in biological tissues to reconstruct a two- or three-dimensional image. From the reconstructed image, the geometry and functions of biological tissues are analyzed. The basic principle of MRI is that the phase of magnetized spin depends on the applied magnetic field. Several imaging technologies based on this phenomenon have already been developed including MRI, MRS (MR spectroscopy), MRA (MR angiography), CSI (chemical shift imaging), MRSI (MR spectroscopic imaging), DPI (diffusion/perfusion imaging), f MRI (functional MRI) and tractography. New technologies such as MRE (MR elastography) for the imaging of mechanical characteristics, hyperpolarized MRI for high-sensitivity imaging and MRT (MR treatment) for navigated medical treatment are also now being actively studied.

Nowadays, medical ultrasound technologies are indispensable for both screening and work-up in different fields of clinical medicine because they are noninvasive, real-time, easy-to-use and low-cost. In particular, for the last ten years, the quality of medical ultrasound images has been markedly improved with technological innovations represented by a digital beamformer and a matrix array probe. Moreover, medical ultrasound imaging is becoming a more useful modality for clinical diagnosis owing to the recent practical use of tissue elasticity imaging for tissue characterization in addition to conventional B-mode imaging for morphological diagnosis and a Doppler method for circulatory evaluation. The principle and features of medical ultrasound imaging are discussed in this paper.

Nuclear medicine imaging enables us to investigate the spatial distribution of radionuclides in living bodies and their temporal variation. Using appropriate radiopharmaceuticals that are closely associated with the activity of cancers and tumors, it can be a sensitive and specific technique for detecting and diagnosing cancers and tumors. The instrumentation is based on the detection of externally emitted photons. Whereas gamma cameras record two-dimensional projection images, SPECT (single-photon emission computed tomography) and PET (positron emission tomography) scanners provide us with three-dimensional tomographic images. A variety of technological innovations that will realize the full potential of nuclear medicine imaging are anticipated.

More than 23 million people suffer from heart failure at this moment in developed countries including Japan. The current gold standard treatment for patients with irreversible heart failure is heart transplantation, but the global shortage of donors limits the number of patients who can receive this treatment. It is in this context that the long-term or permanent use of artificial hearts including ventricular assist devices and total artificial hearts is universally considered the most promising complementary or substitute treatments for heart transplantation. Meanwhile, clinical studies and surveys have revealed that the most frequent complications and the causes of death in the long-term use of artificial hearts are infection, thrombosis and mechanical failure; all of which are typical drawbacks of artificial hearts. It is therefore important to develop the next-generation artificial hearts that have excellent durability with at least 2 years of event-free operation that will provide superior quality of life and can be used for destination therapy to save the patients with irreversible heart failure.

A visual prosthesis is an artificial organ to restore vision in blind patients by applying electrical stimulation to the visual nervous system. My group has been studying “biohybrid” visual prostheses, which combine the characteristics of regenerative medicine and visual prostheses. We have recently been conducting trials on a new stimulation electrode, that contains tubular membrane proteins. Using this electrode, named a proteoelectrode, we can control the membrane potential through the pores formed by tubular membrane proteins. In experiments we observed the assembly of a lipid bilayer and the formation of pores by the fluorescence imaging of ion indicators. This method might be effective as a simple technique for evaluating proteoelectrodes.

It has been reported that the combined treatment with radiation and anti-cancer agents including platinum is useful for the anti-cancer treatment, because of the platinum absorbing the X-ray and releasing the secondary electron. However, the platinum can absorbe only the X-ray with the specific energy, whereas the X-ray used in clinical medicine has the white spectroscopy. And then, the dose of anti-cancer agents is limited due to the unpleasant effects. We try to make the novel chemoradiation treatment system with high specificity and high cytotoxicity, replacing the white X-ray to the monochromatic X-ray, and using the active targeting drug delivery system to increase the platinum concentration in cancer tissue.

The authors have conducted a research project on ultrahigh-resolution retinal imaging using liquid crystal adaptive optics, with the aim of achieving the early diagnosis of complications due to lifestyle-related diseases such as heart disease, diabetes and strokes. In this article, some of our latest achievements are outlined.

On the basis of LSI microfabrication technology, the author is developing innovative nano-bio analytical and/or synthetic systems, which will enable the direct operation and sensing of individual cells and molecules by the fusion of biochip technologies such as microfluidic devices and microarray chips with cell biology and molecular biology. In this article，noninvasive cell diagnosis by the zeta potential measurement using cell electrophoresis chips and microarray chip technology for the high-throughput function screening of the large-scale mutant protein library are introduced.

Polymer ultrathin films of thickness several to tens of nm are known as nanosheets. Here, we report on the fabrication methods, physical properties, and biomedical applications of nanosheets, which have desirable properties such as high flexibility and high adhesiveness. The high biocompatibility of nanosheets made from biomedical polymers and the small amount required to act as a wound dressing material are expected to lead to various biomedical applications.

Most microorganisms are composed of single cells and therefore it is very important to explore their dynamic movement and physiological functions to clarify the potential ability and functions of the single cells composing organisms including human beings. We proposed the employment of microchips fabricated by femtosecond three-dimensional micromachining to investigate the dynamics and functions of microorganisms. Such microchips, referred to as nanoaquariums, can be applied for the investigation of various microorganisms.

Surface plasmon resonance can be a powerful tool of photonic devices for reducing the size and increasing the efficiency of photonic devices. Nevertheless, it sometimes causes an additional source of loss in cases when the properties of surface plasmons are not well understood. This article illustrates the operating mechanisms of surface plasmon resonance in light detectors and light emitters.