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Featured researches published by Showa Aoki.


Journal of Ultrasound in Medicine | 1989

Doppler ultrasound assessment of tumor vascularity in gynecologic disorders.

Toshiyuki Hata; Kohkichi Hata; D Senoh; K Makihara; Showa Aoki; O Takamiya; M Kitao

Real‐time two‐dimensional and pulsed‐wave Doppler ultrasonic examinations were performed on 8 normal volunteers and 97 patients with various gynecologic disorders; the objective was to assess uterine and tumor vascularities. Each arterial blood flow velocity wave‐form was classified into two types. The resistance indices of normal and abnormal flows were greater than .7 and less than .7, respectively. In normal volunteers, abnormal flows were nil. In 8 of 44 patients with benign tumors (18.2%), abnormal flows were evident and all proved to be cases of leiomyoma or adenomyosis. Doppler signals were not detected in 18 of 36 patients with cervical carcinoma (50%) and abnormal flows were noted in only 6 (16.7%). In all cases of endometrial carcinoma, ovarian carcinoma, and trophoblastic disease, typically abnormal flows were noted. Moreover, in most subjects a decrease in blood flows was observed after chemotherapy by anticancer drugs or irradiation. Therefore, Doppler ultrasound is a pertinent and noninvasive tool that can be used repeatedly for assessing the tumor vascularity in gynecologic disorders.


British Journal of Obstetrics and Gynaecology | 1990

Change in ovarian arterial compliance during the human menstrual cycle assessed by Doppler ultrasound

K. Hata; Toshiyuki Hata; D. Senoh; K. Makihara; Showa Aoki; O. Takamiya; M. Kitao

Summary. Ovarian arterial velocimetry, using real‐time two‐dimensional and pulsed Doppler ultrasound, was performed on 36 occasions in nine healthy women with regular menstrual cycles. The change in ovarian arterial compliance was based on the calculation of pulsatility index (PI). In the active ovary carrying a dominant follicle or corpus luteum, the PI in the early follicular phase (mean 6.97, SD 2.01) was significantly higher than that in the late follicular phase (mean 2.36, SD 0.31) (P<0.001), and the PI in the early luteal phase (mean 0.68, SD 0.09) was significantly lower than that in the late follicular phase (P<0.001). The PI in the late luteal phase (mean 0.93, SD 0.16) was significantly higher than that in the early luteal phase (P<0.01). In the inactive ovary, no cyclical changes were seen in the values of PI. There was a significant difference between the values of PI in the active ovary and the inactive ovary in the late follicular, the early and the late luteal phases [2‐36 (SD 0‐31)] vs [6‐29 (SD 1‐02)], [0‐68 (SD 0.09)] vs [6.18 (SD 1.33)], [0.93 (SD 0.16) vs [6‐57 (SD 1.72)] (P<0.001), respectively. Use of non‐invasive Doppler ultrasound to study physiology of ovarian haemodynamics during the menstrual cycle is of great clinical relevance and paves the way for further investigations on sterility.


Gynecologic and Obstetric Investigation | 1998

Three-dimensional ultrasonographic assessment of the umbilical cord during the 2nd and 3rd trimesters of pregnancy

Toshiyuki Hata; Showa Aoki; Kohkichi Hata; Kohji Miyazaki

Objective: To evaluate the umbilical cord and its abnormalities by use of three-dimensional ultrasonography with a specially developed abdominal three-dimensional transducer. Patients and Methods: Ninety-five pregnancies (92 normal, 2 with hydrops fetalis, and 1 with omphalocele) from 14 to 40 weeks of gestation were studied with a specially developed abdominal three-dimensional transducer (3.5 MHz). This system can provide conventional two-dimensional ultrasonography images and can also generate within seconds high-quality three-dimensional images in the surface and transparent mode with no need for an external workstation. A proportion of the umbilical cords (coiled or noncoiled free loop, abdominal insertion, and placental insertion) visualized at each gestational age interval is presented. Results: The proportion of the umbilical cords visualized during pregnancy except for between 24 and 27 weeks of gestation was about 70% (range 64–83%). Optimal visualization of the umbilical cord was achieved between 24 and 27 weeks of gestation. During this period it was possible to adequately depict the umbilical cord in 93% of the cases. The proportions of the noncoiled umbilical cord depicted during pregnancy ranged from 8 to 45%. The detection rate of abdominal insertion of the umbilical cord visualized at 14–19 weeks was 44%; the detection rate decreased thereafter. Placental insertion of the umbilical cord could not be identified after 28 weeks of gestation. In 2 cases with hydrops fetalis, edematous umbilical cord was evident. In 1 fetus, omphalocele was clearly depicted. Conclusions: The new three-dimensional ultrasound technology generates within seconds high-quality three-dimensional images of the umbilical cord, although limitation of viewing direction exists. These results suggest that the new three-dimensional ultrasonography has the potential to be a supplement to two-dimensional ultrasonography and might be useful in identifying abnormal umbilical cords in utero.


Gynecologic and Obstetric Investigation | 1990

Sonographic findings of uterine leiomyosarcoma.

Kohkichi Hata; Toshiyuki Hata; Ken Makihara; Showa Aoki; Osamu Takamiya; Manabu Kitao; Yuji Harada; Saburo Nagaoka

We describe herein various sonographic features of uterine leiomyosarcoma. Transabdominal scanning (TAS) revealed an image indistinguishable from benign leiomyoma, with evidence of degeneration. Transvaginal scanning (TVS) clearly showed the thinness of the myometrium, and the possibility of deep myometrial invasion was suspected at intraoperative open direct ultrasonography (ODU). A very high peak systolic velocity and a slightly increased diastolic component at the periphery of the tumor were evident with pulsed Doppler ultrasound. Thus, TAS, TVS, ODU and Doppler ultrasound will yield useful information for the physician attempting to evaluate the extent and vascularity of uterine leiomyosarcoma.


American Journal of Cardiology | 1987

Intracardiac blood flow velocity waveforms in normal fetuses in utero

Toshiyuki Hata; Showa Aoki; Kohkichi Hata; Manabu Kitao

Sixty-five continuous-wave Doppler ultrasonographic examinations were performed on 57 normal fetuses at 16 to 40 weeks of gestation. Maximal velocities of transmitral, transtricuspid, transaortic and transpulmonary blood flow velocity waveforms were assessed. Transmitral maximal velocity, transtricuspid maximal velocity, transaortic maximal velocity and transpulmonary maximal velocity correlated well with gestational age. The ratio of transtricuspid maximal velocity/transmitral maximal velocity was at least 1 in 44 of 45 fetuses (97.8%). In the ratio of transpulmonary maximal velocity/transaortic maximal velocity, the characteristic change was not evident. Therefore, continuous-wave Doppler ultrasonographic measurement of fetal intracardiac blood flow velocity waveforms in utero can aid in analyzing the physiologic circulatory hemodynamics.


Archives of Gynecology and Obstetrics | 2009

Microwave endometrial ablation as an alternative to hysterectomy for the emergent control of uterine bleeding in patients who are poor surgical candidates

Shamima Yeasmin; Kentaro Nakayama; Masako Ishibashi; Atsuko Katagiri; Kouji Iida; Naomi Nakayama; Showa Aoki; Yasushi Kanaoka; Kohji Miyazaki

BackgroundMicrowave endometrial ablation is a new, minimally invasive treatment option for menorrhagia. Its popularity in many countries is increasing due to its safety and simplicity.CasesWe treated menorrhagia due to submucosal myomas in two patients with a modified microwave endometrial ablation device. Surgery was contraindicated in the first patient secondary to medical co-morbidities and in the second patient because of acute hemorrhagic shock. In both cases, the operation was highly effective and each patient was satisfied with her treatment outcome.ConclusionGiven its safety, simplicity, and effectiveness, microwave endometrial ablation may be widely adopted for the emergent control of uterine bleeding in patients with poor surgical candidates.


Gynecologic and Obstetric Investigation | 1987

Ultrasonographic Identification of the Human Fetal Gallbladder in utero

Kohkichi Hata; Showa Aoki; Toshiyuki Hata; Fuminori Murao; Manabu Kitao

Ultrasonographic studies of the human fetal gallbladder were performed in utero on 149 fetuses ranging from 20 to 39 weeks of gestation. The gallbladder could be identified in 37.5% (20-23 weeks) to 64.7% (24-27 weeks) after 20 weeks of gestation. The normal sonographic characteristics of the fetal gallbladder were described and the area of fetal gallbladder, the length and the width were measured, respectively. The ultrasonographic identification of the fetal gallbladder is a first step in antenatal detection of congenital anomalies affecting the gallbladder.


Gynecologic and Obstetric Investigation | 1998

Three-Dimensional Ultrasonographic Visualization of Multiple Pregnancy

Toshiyuki Hata; Showa Aoki; Kohji Miyazaki; Osamu Iwanari; Kohji Sawada; Toshihiro Tagashira

Our purpose was to describe interrelationships and contacts between twins in utero by use of three-dimensional ultrasonography with a specially developed abdominal three-dimensional transducer. Thirteen twin pregnancies (3 monochorionic and 10 dichorionic pairs) and one triplet pregnancy (trichorionic triplet) from 9 to 36 weeks of gestation were studied with a specially developed abdominal three-dimensional transducer (3.5 MHz). This imaging system can provide conventional two-dimensional ultrasonography images and can also generate within seconds high-quality three-dimensional images in the surface and transparent mode with no need for an external workstation. Interrelationships and contacts between twins or triplets are described. Various types of contacts (head/body/arm/leg) and interrelationships were clearly visualized. Crowding of in utero twin fetuses increased with advancing gestation. Sometimes two placentas and dividing membrane were beautifully depicted. In one triplet pregnancy, the interrelationships among 3 fetuses and dividing membranes were easily recognized. Three-dimensional ultrasonography provides a novel means of visualizing multiple pregnancies in utero. These results suggest that three-dimensional ultrasonography has the potential to be a supplement to two-dimensional ultrasonography and would be useful in evaluating the interhuman contacts and crowdings of twin and triplet fetuses in utero.


Gynecologic and Obstetric Investigation | 1990

Magnetic Resonance Imaging of the Fetus: Initial Experience

Toshiyuki Hata; Ken Makihara; Showa Aoki; Kohkichi Hata; Manabu Kitao

Magnetic resonance imaging (MRI) examinations were made on 9 high-risk fetuses (poor fetal growth, 3; maternal manic-depressive psychosis, 1; maternal systemic lupus erythematosus, 1; habitual intraut


Gynecologic and Obstetric Investigation | 1997

Interleukin-4, interleukin-10, and soluble tumor necrosis factor receptors in cord blood.

Toshiyuki Hata; Takae Kawamura; Ritsuto Fujiwaki; Showa Aoki; Kohkichi Hata; Katsuya Inada

OBJECTIVE We assessed cord blood for levels of interleukin-4 (IL-4), interleukin-10 (IL-10), and p55 (sTNFR-I) and p75 (sTNFR-II) soluble tumor necrosis factor receptors. STUDY DESIGN Umbilical cord IL-4, IL-10, tumor necrosis factor alpha (TNF alpha), sTNFR-I, and sTNFR-II were measured in 21 normal appropriately grown newborns delivered vaginally (normal pregnancy), and 3 abnormal pregnancies (1 preterm delivery, 1 premature rupture of membranes with chorioamnionitis, and 1 abruptio placentae with fetal and neonatal distress). Umbilical cord arterial blood pH and PO2 were also measured. RESULTS The TNF alpha, sTNFR-I, and sTNFR-II were detectable in all cord blood samples in normal pregnancies. IL-4 was detected in 10 of 21 samples (47.6%), and IL-10 was undetectable in normal pregnancies. IL-10 could be detected in the cases with chorioamnionitis and abruptio placentae. Soluble tumor necrosis factor receptors in the case with preterm delivery and the case with abruptio placentae were elevated compared with the levels in control samples. CONCLUSION Both the p55 and p75 soluble tumor necrosis factor receptors are physiologic constituents of term cord blood. An immunosuppressive role of IL-10 and a protective role of soluble tumor necrosis factor receptors are suggested in abnormal pregnancies. However, in view of the small number of abnormal pregnancies, these observations must be considered preliminary.

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Daisaku Senoh

Kagawa Prefectural College of Health Sciences

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