Yoshikatsu Tanahashi

Transrectal ultrasonotomography of the prostate.

New equipment for transrectal ultrasonomography has been developed. Wth this equipment an excellent cross-section picture of various intrapelvic organs is easily obtained. Diagnostic application of the technique is particularly significant for abnormalities of the prostate because the shape of the prostate cannot be revealed by x-ray. Diagnostic criteria for prostatic disease are described, with the demonstration of typical cases. In a test by well trained physicians the diagnostic accuracy of the new technique was more than 80 per cent. Ultrasonotomography provided for precise measurement of prostatic size. Transrectal ultrasonotomography is a promising new diagnostic technique that yeilds abundant information not available with former methods of examination. The procedure is likely to become one of th most important diagnostic tools in the field of urology.

Clinical Evaluation of Inside Echo Patterns in Gray Scale Prostatic Echography

Improved gray scale echograms in transrectal ultrasonography clearly can visualize the anatomical structure of and pathological changes in the prostatic gland. This study includes the classification of ultrasonic findings from the prostatic gland into acoustical pattern groups--solid, cystic and mixed--as well as into pathological-anatomical pattern groups--internal gland, external gland, nodule, stone and miscellaneous. The diagnostic accuracy of prostatic diseases using pattern analysis of prostatic inside echoes was 89 per cent, a 9 per cent improvement over that provided by conventional display.

Mass Screening Program for Prostatic Diseases with Transrectal Ultrasonotomography

A special chair-type apparatus for transrectal ultrasonotomography was developed in our laboratory 3 years ago. We did a mass screening program for prostatic disease, using this equipment as the primary study in the system. The 132 apparently normal men evaluated ranged in age from 40 to 76 years (mean 55.0). The 48 patients suspected of having prostatic disease underwent secondary studies, consisting of the usual urological examinations. Prostatic disease was detected in 24 cases, including 18 cases of benign prostatic hyperplasia. Thus, the model program revealed an extraordinarily high prevalence of latent prostatic disease among apparently normal older men.

Development of an endoscopic tactile sensor using PVDF films

In this work, a prototype Polyvinylidene Fluoride (PVDF) tactile sensor for endoscopic application has been developed. The sensor aims to measure hardness, which is one of the information of tactile perceptions, of biomedical tissue. This sensor is composed of two PVDF films, a silicone cylindrical column, and an aluminum cylinder. And the classification of hardness is concerned with the ratio of these PVDF outputs. In this paper, two sensors are fabricated using two silicone cylindrical columns with different Youngs modulus. The performance evaluation of each sensor is conducted using 6 silicone rubbers as measuring object. The experimental results correspond with the simplified theoretical analysis and the proposed sensor can distinguish a difference of elastic property.

Palpation sensor using two PVDF films

In this work, a prototype polyvinylidene fluoride (PVDF) palpation sensor has been developed. The sensor aims to measure stiffness, which is one of the information of biomedical tissue by palpation. The sensor is composed of two PVDF films, a silicone cylindrical column, and an aluminum cylinder. And the classification of hardness is concerned with the ratio of these PVDF outputs. In this paper, the output behavior of the palpation sensor was evaluated in detail by the experimental and numerical approach, and the suitable design to diagnose by the stiffness of tissue was investigated. Using the finite element analysis, the sensor output behavior was predicted. It is confirmed that the analysis is available for investigation of the dimension and the limitation of the sensor against the measuring object.

Active palpation sensor for detecting prostatic cancer and hypertrophy

This paper is concerned with the development of an active palpation sensor for detecting the prostatic cancer and hypertrophy. The receptor of the sensor is a polyvinylidene fluoride (PVDF) film placed on the surface of a sponge rubber layer. It is mounted on a linear z-translation bar and inserted into the examinees rectum being protected by a medical rubber glove. After positioned faced to the prostate gland, the sensor probe is driven sinusoidally at about 50Hz with peak-to-peak amplitude 2mm. The voltage signal from the PVDF film is integrated over the sampling period and used as the output of sensor for extracting the features of the collected data. The evaluation of stiffness by the sensor on 27 normal and unhealthy prostate glands are compared with the results of diagnosis by the doctors palpation. It is shown that the output of sensor becomes greater with an increase of the stiffness of the prostate gland, which has good correlation with the doctors evaluation on the stiffness. Further results on the laboratory test reconfirm that the present sensor well discriminates the stiffness of the prostate glands in vivo and non-invasively.

Development of a three-dimensional tactile sensor for minimally invasive instruments

This paper proposes a three-dimensional tactile sensor that can be attached to the tip of an endoscope or catheter to detect the tip contact conditions. Because conventional minimally invasive instruments (MIIs) without a sensor cannot detect the posture and applied force at the tip, operators cannot obtain accurate information during minimally invasive surgery (MIS). The sensor consists of an elastic cylinder and three strain g auges. The gauges, located on the surface of the cylinder at intervals of 120 � , are used to detect deformation of the cylinder caused by contact with the inner walls of the patients organs. The output voltage signals of the gauges are approximated by a sinusoidal function with a phase difference of 120 � . The three-dimensional contact angle and applied force at the tip of the sensor can be estimated accurately from the three sinusoidal functions and measured output voltage signal from the gauges. The operating principle of the sensor is examined through several experimental conditions. To improve the effectiveness of minimally invasive surgery (MIS), it is necessary to develop better endoscope and catheter techniques. Conventional minimally invasive instruments (MIIs) improve the quality of life (QOL) of patients, because they can begin rehabilitation only a few days after MIS. However, the manipulation of MIIs is difficult because opera tors cannot obtain accurate information about the tip contact conditions of MIIs with the walls of the patients organs. In conventional MIS, the operator manipulates the MII based on both the tactile sensations transmitted to their hand via the MII and the two-dimensional X-ray image information. However, tactile sensations are a mixture of the contact and friction forces with the walls of organs, and it is difficult to discriminate these forces precisely. Therefore, operators need to be highly trained; a lack of this skill on their part may lead to critical accidents. The abovementioned issues have necessitated the development of mechanisms for detecting the posture of the MII tip. Some active devices (1-4) have been developed to help manipulate catheters (3) and endoscopes (4). In these devices, shape memory alloys (SMAs) are used as actuators. In addition, inchworm locomotion (5) has been developed. An inchworm-like robot with a bellows mechanism

Laser Litholapaxy of Renal and Ureteric Calculi

Department of Urology, Tohoku University School of Medicine, Sendai, Japan 980 Percutaneous nephrolithotomy was performed on 175 cases in our clinic during these 33 months. Clinical success was recognized in 99% of cases (complete removal =92%). Ten percents of these cases were treated with continous wave YAG laser irradiation. Laser litholapaxy is more effective than the other two methods of stone disintegration (intensive ultrasound and electrohydraulic effect ) in cases, where stones have dark colour, smooth surface or soft (organic) components.