Masahiko Kanda

Clinical applications of ICG Finger Monitor in patients with liver disease

The indocyanine green (ICG) Finger Monitor system is a non-invasive indication of ICG concentrations in the blood. In this study, significant correlation was found between the sensor signal voltage and plasma ICG concentrations ranging from 0.04 mg/dl to 1.0 mg/dl (r = 0.998, P < 0.001) in vivo. The ICG clearance curve showed an initial sharp rise 20-30 s after bolus injection, followed by a small rise. The concentration then deceased exponentially. In 196 patients with chronic liver disease, there was a close correlation between the KICG (plasma disappearance rate) and R15 (blood retention ratio at 15 min) (r = 0.886, P < 0.001, r = 0.912, P < 0.001) and corresponding values calculated by the conventional ICG method. In 263 cases with chronic liver disease, the plasma disappearance rates calculated using this monitor (mean +/- S.D.) were 0.156 +/- 0.064 (n = 20) in the control group, 0.129 +/- 0.060 (n = 92) in the chronic hepatitis group, 0.048 +/- 0.025 (n = 59) in the cirrhosis group and 0.059 +/- 0.03, (n = 92) in the group with hepatocellular carcinoma. A significant difference in the plasma disappearance rate and blood retention ratios 15 min after injection of ICG using this system was observed between control cases and the chronic hepatitis and cirrhosis groups (P < 0.0001). In 36 cases, the time from injection to the appearance of ICG in the fingertip significantly decreased in the cirrhosis group (P < 0.01). The ICG Finger Monitor system was shown to be useful clinically as well as for research due to its accuracy and non-invasive nature.

Fiber optic reflectance spectrophotometry system for in vivo tissue diagnosis.

Fiber optic probes for a small portable reflectance spectrophotometry system for noninvasive clinical diagnosis have been developed. A slender fiber optic probe, 3 m long, 2.4-mm diameter, which goes into the channel of a fiber optic endoscope, has been developed as the standard probe. To expand the availability and capability of this reflectance spectrophotometry system, some variations of the fiber optic probes were developed: contact sensor, pressure sensor, attachments for dental use, and a modified-shape probe head for continuous monitoring. The feasibility of these fiber optic probes was examined experimentally.

Continuous Monitoring Of Cardiogreen Removal By A Diseased Liver Using An Optical Sensor

A non-invasive monitoring instrument of Cardiogreen (Indocyanine green) dye removal by a liver, which uses a new optical sensor and analytical method, was developed. The optical sensor utilizes 2 light emitting diodes operating at 810 and 940 nm wavelength, and 1 photodiode to sample the transmittance of light through the tip of the index finger. Since the transmittance of light is affected most by changes in both blood volume and the concentration of the dye in blood, adequate analysis must be taken to eliminate the change of blood volume in vivo. Fortunately, for a wavelength near the 805 nm isobestic wavelength, the transmittance of light does not vary with hemoglobin oxygen saturation, however it varies with hemoglobin content. In addition, at 805 nm wavelength, absorption by the dye is quite high, but it is quite low at 940 nm wavelength. Accordingly, the authors developed a new analytical. method by using the transmittance of light measured through the tip of the index finger before and after the dye injection. As a result, the change of blood volume in vivo was eliminated by using the newly developed analytical method. Therefore, the dye information was only measured. A quantitative estimation of plasma disappearance rate (PDR) in hepatic diseased patients which was obtained using this instrument showed that PDR values concurred fairly well with the PDR values from the blood sampling method.

Development of a noninvasive monitoring instrument for serum Indocyanine Green dye concentration.

A noninvasive instrument to monitor serum Indocyanine Green (ICG) dye removal by the liver, which uses a new analytical method and an optical sensor, has been developed. The principal elements of the optical sensor are two light-emitting diodes at 810- and 940-nm wavelengths and a photodiode to detect light transmittance through the fingertip. A new analytical calibration method to compensate for the effect of blood volume variations has been developed. Thereby, only ICG concentration could be extracted. In addition, through clinical evaluation of hepatic disease patients, the correlation between serum ICG disappearance rates by this method and the conventional blood sampling method has been confirmed as evidence of its usefulness.

Flow cytometer using a fiber optic detection system

A flow cytometer with a new hybrid flow cell has been developed. The hybrid flow cell was constructed closed-type quarts curvets which produces a parabolic profile of flow velocities. It was involved a fiber-optic detecting unit for a high sensitivity collection and had a jet nozzle and a PZT device for droplet formation aimed to cell sorting. A optical fiber that consists of a glass core and have a core diameter of 200 micrometers with NA of 0.5 have been successfully used for the collection of side scatter and fluorescent signals. Two detecting fibers mounted in a hybrid flow cell with pith of 250 micrometers are designed to individually detect fluorescent signals excited by 2 lasers, which are a compact air-cooled AR laser (488 nm: 20 mW) and a semiconductor laser (640 nm: 15 mW). As a result, a sensitivity of our flow cytometer is 300 MESF determined using fluorescein-labeled beads and 2 scatter and 6 fluorescent signals could successfully be detected. Typical patterns of cell cycle were observed with Daudi human Burkitt Lymphoma cell lines stained with PL. Furthermore, the alignment requirements are more simplified because of a hybrid flow cell stably mounted.