Tomomoto Ishikawa

Ultrasonic Evaluation of Seminiferous Tubules by Frequency Map

This paper describes a seminiferous tubules evaluation system using an ultrasonic probe. This system evaluates diameters of seminiferous tubules for azoospermia patients. We employ a 5.0MHz ultrasonic single probe. In the experiment, we employ large and small nylon lines as the healthy and unhealthy seminiferous tubules. We acquired the waveforms by the ultrasonic probe and calculated frequency spectrum by short-time Fourier transform. The system visualizes the position of small and large line by a frequency map. The frequency map shows distance and frequency value. In the results, our proposed method detected the large and small lines. Additionally, the system evaluated distance between probe and these lines clearly. The proposed method thus successfully evaluated the position of the large lines.

Blood flow detection under skull by Doppler effect

This paper describes a trans-skull ultrasonic system that measures the blood flow velocity in brain under skull. In this system, we use an ultrasonic array probe with the center frequency of 1.0 MHz. The system determines the blood flow and locate blood vessel by Doppler effect. This Doppler effect is examined by the center of gravity shift in the frequency domain. We use three silicon tubes of different thickness imitated to blood vessel. We confirmed the change of frequency quantity of Doppler effect according to the water current velocity. The experimental result shows that the system detects the flow velocity by Doppler effect under skull and do automatic extracting method of water current.

Fuzzy object growth model for newborn brain using Manifold learning

To develop a computer-aided diagnosis system for neonatal cerebral disorders, some literatures have shown atlas-based methods for segmenting parenchymal region in MR images. Because neonatal cerebrum deforms quickly by natural growth, we desire an atlas growth model to improve the accuracy of segmenting parenchymal region. This paper proposes a method for generating fuzzy object growth model (FOGM), which is an extension of fuzzy object model (FOM). FOGM is composed of some growth index weighted FOMs. To define the growth index, this paper introduces two methods. The first method calculates the growth index from revised age. Because the growth index will be different from person to person even through the same age, the second method estimates the growth index from cerebral shape using Manifold learning. To evaluate the proposed methods, we segment the parenchymal region of 16 subjects (revised age; 0-2 years old) using the synthesized FOGM. The results showed that FOGM was superior to FOM, and the Manifold learning based method gave the best accuracy. And, the growth index estimated with Manifold learning was significantly correlated with both of revised age and cerebral volume (p<;0.001).

Fuzzy object shape model for newborn brain MR image segmentation

In magnetic resonance (MR) images, finding a small change of parenchyma in newborn babies brain significantly helps physicians to diagnose suspicious hypoxic-ischemic encephalopathy patients. However, there are no computer-aided methods because an automated segmentation algorithm has not been established yet. This paper proposes a new image segmentation method for parenchyma segmentation in T2-weighted MR images. The proposed method introduces a fuzzy object model, which has a fuzzy boundary and MR signal learned from training data. It segments the parenchyma by maximizing a fuzzy degree of deformable surface model. The fuzzy degree is estimated by using the fuzzy object model. To validate the proposed method, we recruited 12 newborn babies whose revised ages were −1 month to 1 month. 9 subjects were used to generate the fuzzy object model, and the remained subjects were used to evaluate the segmentation accuracy. The segmentation accuracy has been evaluated by using sensitivity and false-positive ratio, which were calculated by comparing delineation result (ground truth).

A neonatal brain MR image template of 1 week newborn.

PurposeMagnetic resonance imaging (MRI) is often used to detect and treat neonatal cerebral disorders. However, neonatal MR image interpretation is limited by intra- and inter-observer variability. To reduce such variability, a template-based computer-aided diagnosis system is being developed, and several methods for creating templates were evaluated.MethodSpatial normalization for each individual’s MR images is used to accommodate the individual variation in brain shape. Because the conventional normalization uses as adult brain template, it can be difficult to analyze the neonatal brain, as there are large difference between the adult brain and the neonatal brain. This article investigates three approaches for defining a neonatal template for 1-week-old newborns for diagnosing neonatal cerebral disorders. The first approach uses an individual neonatal head as the template. The second approach applies skull stripping to the first approach, and the third approach produces a template by averaging brain MR images of 7 neonates. To validate the approaches, the normalization accuracy was evaluated using mutual information and anatomical landmarks.ResultsThe experimental results of 7 neonates (revised age 5.6 ± 17.6 days) showed that normalization accuracy was significantly higher with the third approach than with the conventional adult template and the other two approaches (P <xa00.01).ConclusionThree approaches to neonatal brain template matching for spinal normalization of MRI scans were applied, demonstrating that a population average gave the best results.

A testicular tubule evaluation method by ultrasonic array probe

This paper describes a testicular tubules evaluation using 1.0MHz ultrasonic array probe. In this system, we evaluate a diameter of testicular tubules. We employ an ultrasonic array probe with the center frequency of 1.0MHz. We employ evaluation index that cumulative relative frequency of amplitude values. In the experiment, we employ 24 nylon lines as the testicular tubules. Amplitude of large nylon line echo is larger than that of small nylon echo. For the evaluation, we calculate cumulative relative frequency amplitude of acquisition data. Fuzzy if-then rules are made by the cumulative relative frequency of large and small lines. We evaluate a rate of large lines among all lines by using the fuzzy MIN-MAX center-of-gravity method. In this experiment, the proposed method successfully evaluated the rate of the large lines. We changed the rate of large lines in 24 nylon lines, and tested our method 20 times for each rate. We evaluated the rate with 5.77 % in mean absolute error.

Neonatal brain MRI normalization with 3-D cerebral sulci registration

MR image registration (IR) has been used in brain function analysis, voxel-based-morphometry, etc. The conventional IR methods mainly use MR signal based likelihood. However, they cannot prevent miss registration of different gyri because they do not evaluate correspondence of sulci. Also, we cannot directly apply methods for adult brain to neonatal brain because there are large differences in MR signal and sulcal width. This paper focuses on neonatal brain MR images, and introduces a new feature called sulcal-distribution index (SDI), which is calculated from MR signal around the cerebral surface. Next, this paper proposes a non-rigid 3-D IR method based on a flattening with SDI. The likelihood used is mutual information of SDI. The new method evaluates the correspondence of cerebral sulci. And, the method will be effective for neonatal brain in which the accurate delineation of cerebral surface is difficult because the method evaluates the MR signal around the cerebral surface. Results in 3 neonates (modified age; 3-5 weeks) showed that the method registered one brain with the other brain successfully.

An Ultrasonic Imaging for Seminiferous Tubules Beyond the Wavelength Limit

This paper describes an ultrasonic imaging technique for seminiferous tubules in testicle. An image is made by particular frequency data derived by short-time Fourier transform. Thus, the image has particular frequency components. The image indicates an object that has a frequency component being different from others. In our experiment, we employ two kind nylon lines with different diameter as seminiferous tubules. For a performance test, we make a measurement object consisting of the nylon lines. For a phantom test, we make a phantom of a testicle. The phantom consists of a water filled rubber tube including the nylon lines. We scan and acquire ultrasonic reflection wave data of them. Next, we make images of them by our imaging technique. As the results, the image of the object indicated the line depth with high accuracy, and the image of the phantom successfully extracted echoes of two kind lines.

Human brain ultrasound-mediated diagnosis in emergency medicine and home health care

This paper describes human brain ultrasound-mediated diagnosis in emergency medicine and home health care. The ultrasonic equipment has many advantages, for example, the very simple operation to touch to the body surface diagnosis enables real-time visual recognition for heart beat and unborn baby moving, and so on. The ultrasonic diagnosis is safety to human body and many repetitions. The goal of our research is the portable and real time brain diagnosis under the thick-skull. In our experiment, we employ two ultrasonic array probes with the center frequency of 1.0MHz and 0.5MHz. The choice of ultrasonic frequency is a trade-off between spatial resolution of the image and imaging depth. We perform the experiment with a cow scapula as a skull and a steel sulcus as a lateral cerebral sulcus. As the results, the synthesized image in Wavelet transform has higher efficiency than the other synthesizing on the images for the bone and the sulcus.

Foot age estimation for fall-prevention using sole pressure by fuzzy logic

This paper describes a foot age estimation system using fuzzy logic. The method employs sole pressure distribution change data. The sole pressure data is acquired by a mat type load distribution sensor. The proposed method extracts step length, step center of sole pressure width, distance of single support period and time of double support period as gait features. The fuzzy degrees for young age, middle age and elderly groups are calculated from these gait features. The foot age of the walking person on the sensor is estimated by fuzzy MIN-MAX center of gravity method. In the experiment, the proposed method estimated subject ages with good correlation coefficient.