Iwao Fujimasa

Development of a new infrared imaging system: an infrared image superimposed on the visible image

The infrared imaging, especially far infrared thermography, is a typical non-invasive measurement method in clinical medicine. However, the applications have been used mainly in clinical testing laboratory, and not used in outpatient clinics or operation rooms with on-line mode. The reason exist on the difficulty of the positional identification from the infrared image. The authors have been testing combination of visible image and infrared image. Recently, compact non-cool infrared cameras become commercially available. Using the camera, a new infrared imaging system by which one can observe superimposed infrared image on its visible image have been developed. The image from an object is separated infrared and visible light using Inconel metal coated mirror and guides to an infrared camera (Thermal Vision LAIRD 3A) and a video camera (Handyscope) separately. The measured images are mixed digitally with a image mixer (Digital Video Mixer MX-1) and display a overlapped image on a monitor. The developed system was tested on an animal experiment and was evaluated its feasibility for clinical usage.

Implantable total artificial heart: history and present status at the University of Tokyo

The University of Tokyo has been involved in research and development of the artificial heart since 1959. This paper is a brief review of 40 years of total artificial heart research in the University of Tokyo. Many types of artificial heart and various kinds of materials, blood pumps, valves, drive units, control methods, and pathophysiology have been investigated in our original fashion. The longest survival was 532 days for a goat with a total artificial heart (TAH) placed on the chest wall. These results made us take a step toward the development of an implantable TAH. Two kinds of implantable TAH are now being developed: FTPTAH (flow-transformed pulsatile total artificial heart) and UPTAH (undulation pump total artificial heart). Recently, a goat survived for 31 days with an UPTAH.

Far infrared medical image database on World Wide Web

In order to set up international standards for medical infrared thermography the authors have been developing an international communication tool on the World Wide Web (WWW) named Biomedical Thermology Homepage (http://biomed.poli-sci.saitama-u.ac.jp/bmth/). The methodology and system concept have been reported (I. Fujimasa et al., 1996). In this report, the concept and methodology of the image database named Gallery are reported. The keynotes are how one establishes remote access of image handling software to analyze common source binary images in the database. The authors have developed software which was written with Visual Basic and JAVA. The system, which has included more than 20000 binary images, has been tested for its feasibleness from remote sites.

Structural and functional tissue analysis under skin using near infrared spectral imaging

The infrared imaging technique will become a typical noninvasive measurement method in clinical medicine. However, the pathophysiological meaning of infrared imaging has not been analyzed schematically. The authors have developed an infrared imaging system, which can detect spectroscopic images from near infrared images to far infrared thermography. Near infrared images are taken by a cooled charge-couple-device (cooled CCD) applying an active light source such as a halogen light and laser diodes in reflecting and transparent mode. Middle infrared images are measured by an infrared camera, which can detect short wavelengths less than 3.0 microns. Far infrared images are taken by a dynamic thermographic instrument to measure radiated rays. Using projected infrared rays of 880 nm, the vascular network in subcutaneous tissue has been observed in transparent and reflective mode. Using infrared rays of 760 nm and 800 nm, blood volume and oxygenation images of subcutaneous tissue have been obtained in dynamic mode. A near infrared image of subcutaneous tissue combined with a thermal image of skin surface which was simultaneously taken by an image overlapping method, and the pathophysiological function of cutaneous tissue was analyzed.

Development of an image processing software for medical thermogram analysis using a commercially available image processing system

The medical far infrared (FIR) imaging system has recently been modified to be more sensitive, rapid and cheap. Also, the image format for processing on a personal computer and output format from integrated circuit of a FIR sensor have gradually been standardized. The objective of the report is to develop an application software to analyze clinical FIR images. We developed new programs which are written as macro programs on commercially available image processing software and by which any digital image data with known data format becomes applicable to the standard FIR image analysis system. NIH Image was introduced as the image processing software. Sequences of calls or routines for medical oriented image processing were written with macro codes in Macintosh computers. We aimed to obtain the same image processing functions which had been developed for medical computer thermography systems. Every source FIR image was converted into temperature images (thermograms). Marking on the same temperature region (isotherm), making temperature profiles (line scan) and temperature histograms of region of interest (ROI), drawing temporal temperature difference images (dT thermogram), comparing the temperature difference of two ROI (asymmetry detection thermogram), and displaying thermography index thermogram (TI thermogram) have been developed.

System dynamics analysis of dynamic far infrared images in medicine

The objectives of the report are to develop a simulation model for thermal convection near the skin surface, to make an application software for analyzing dynamic far infrared images, and to establish a new analysis system of dynamic thermography for clinical medicine. Firstly, dynamic thermal images were taken by a FIR camera (Thermal Vision LAIRD 3A, Nikon) and stored in a digital-videotape. Secondary, the images were sent to a Macintosh computer using DVCap software (Canon) and converted to a QT movie. Thirdly, the QT movie was processed with a simulation model in the NIH image system. In order to analyze the dynamic images a thermal convection model was developed using system dynamics software (STELLA, High Performance Systems Inc.). After thermal and mechanical stresses were applied to a human body, the dynamic changes of skin temperature were observed by the system. Blood flow rate distribution of cutaneous tissue and sympathetic control factors were detected using the system.

Antithrombogenic Regimen for Clinical Use of Pneumatic Ventricular Assist Device

Antithrombogenic regimens for pneumatic ventricular assist devices (VADs) were evaluated in 77 VADs used clinically in a total of 70 patients. Macroscopic thrombus formation in the devices was assessed in relation to potential risk factors, including hematological and hemodynamic derangements, during use of the VAD. Effects of varions antithrombogenic regimens were assessed on the basis of this risk analysis. A thrombus score was used to quatititate the grade of thrombosis. As a linear increase in the thrombus score was noted in accordance with increase in support duration, a time-adjusted thrombus score was calculated to compare scores in anticoagulant groups with different pumping duration. The scores appeared to be high in patients in those groups which received gabexate mesilate (GM, a protease inhibitor). Heparin was not demonstrated to be effective in this study. Univariate risk analysis showed that the use of GM, low-flow pumping, prolonged pumping, and semi-normal platelet count were significantly correlated with the incidence and grade of thrombosis. A multivariate regression analysis also indicated that the use of GM, low-flow, and prolonged pumping were detrimental to anti-thrombogenicity. As the use of GM was demonstrated to be predominantly detrimental, its withdrawal from use should lead to a substantial reduction in the incidence and grade of thrombosis.