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Biomedical subjects

Y Itai

Publications and source records attributed to Y Itai.

At least 73 records · Page 4Linked to original sources
PubMed1999

Dynamic intravenous coronary angiography using 2D monochromatic synchrotron radiation.

A method of examination for coronary artery disease that is less invasive and easier than coronary angiography (CAG) has been sought. We have developed a dynamic intravenous coronary angiography (IVCAG) system using synchrotron radiation (SR) and have used it clinically. Four patients suspected of having angina pectoris underwent IVCAG. An SR beam was reflected asymmetrically with a silicon crystal to produce a wide (150 mm x 80 mm) and monochromatic (37 keV) X-ray beam, with an energy level to achieve high sensitivity to the contrast agent. Following an intravenous injection of contrast agent, irradiation was applied for 4 ms periods at 33 ms intervals for dynamic IVCAG at 30 images s-1. Images were acquired with an image intensifier and recorded with a digital fluorography system. The dynamic images permitted clear visualization of the coronary arteries and permitted evaluation of coronary anatomy. Two patients exhibited no stenotic lesions, one patient had a 90% stenosis in the right coronary artery, and the remaining patient had a 25% stenosis at the site of previous percutaneous transluminal coronary angioplasty in the left anterior descending artery (LAD). The total irradiation doses used for IVCAG were less than those for conventional angiography. Dynamic IVCAG can be readily used for the evaluation of coronary arteries.

Aged↗
PubMed1999

Does resection of small liver metastases from colorectal cancer improve survival of patients?

Because the size of metastases greatly affects their detection, we retrospectively investigated the influence of the size of liver metastases on survival after hepatic surgery. The subject group study consisted of 77 patients who underwent liver surgery for metastases from colorectal cancer. The survival rate after hepatic surgery was analysed using multivariate Cox's proportional hazards model with the following variables: (1) size of dominant metastases (Small: < 3 cm; Medium: > or = 3 cm and < 6 cm; Large: > or = 6 cm); (2) synchronous versus metachronous resection; (3) solitary versus multiple metastases. The size of dominant metastases (p = 0.035) and synchronous versus metachronous resection (p = 0.0009) were independently associated with survival after liver resection. No association was found, however, for solitary versus multiple metastases. The survival of the Large group was much poorer than that of the Small group (p = 0.0168) and that of the Medium group (p = 0.0205), with statistically significant differences. No statistically significant difference was seen between the Small and the Medium groups (p = 0.7963). This study showed that long-term survival following resection of metastases was much poorer when metastases were 6 cm or greater in diameter. With regard to metastases less than 6 cm in diameter, resection of the smallest of these (less than 3 cm) did not appear to improve survival.

Adult↗
PubMed1999

Differential diagnosis of gynaecological "stained glass" tumours on MRI.

Although multilocular cystic gynaecological masses in which the loculi show variable signal intensity on both T1 and T2 weighted images have been considered to be mucinous cystadenoma or adenocarcinoma, other gynaecological tumours can demonstrate this "stained glass" appearance. These include mature cystic teratoma, fibrothecoma, endometrioma, Brenner's tumour of the ovary and degenerated leiomyoma of the uterus, all of which may mimic mucinous tumours of the ovaries.

Diagnosis, Differential↗
PubMed1999

[Application of a new MR microscope using an independent console system (MRMICS) for biological tissues in vitro].

We studied microscopic MR images of the normal appendix in vitro using a new MR microscope system: MR Microscope using an Independent Console System (MRMICS). The MRMICS was placed in the clinical MR room, and the probe box was fixed on the bed of the 1.5 T clinical MR machine. T1-, T2-, and proton density-weighted images were obtained using spin echo sequences with an in-plane pixel size of 100 x 100 microns. Zonal structures of the appendix were clearly demonstrated with different contrast by different sequences. Therefore, the MRMICS is a useful add-on system for investigating microscopic MR images of biological tissues in vitro.

Appendix↗
PubMed1999

[MR imaging of the posterolateral aspect of the knee].

The structures of the posterolateral aspect of the knee were evaluated with axial MR images. One hundred twelve knees of clinical cases without posterolateral injury were retrospectively reviewed, and 30 knees of 15 volunteers with no history of knee injury or pain were evaluated. The amount of joint effusion and visualization of the lateral collateral ligament (LCL) and popliteal tendon were classified according to three grades. The LCL and popliteal tendon were identified in 111 clinical cases (99%) and 28 volunteer knees (93%). Visualization of the LCL and popliteal tendon was facilitated in the presence of both joint effusion and fluid collection between the LCL and popliteal tendon. Fluid collection posterior to the femoral attachment of the popliteal tendon was seen in 79 clinical cases (71%) and 20 volunteer knees (67%). Based on cadaveric study, this was considered to be a potential fluid space for communication to the joint space.

Adolescent↗
PubMed1999

[Patterns of initial treatment failure of esophageal cancer following radiotherapy].

Sixty patients with stage I-III esophageal squamous cell cancer treated by definitive radiotherapy (RT) were analyzed for patterns of treatment failure. Patients were treated by external RT alone (n = 45) or in combination with intraluminal RT (N = 15) when suitable, with prescribed total doses ranging from 59.4 to 104.4 Gy. Concurrent chemotherapy consisting of cisplatin and/or 5-fluorouracil was administered to 19 patients. The two-year actuarial survival rate and two-year disease-free survival rate were 29.5% and 18.3%, respectively. Two-year failure rates were 66.5%, 36.9%, and 3.8%, for the esophagus, lymph nodes, and other sites, respectively. Two-year esophageal failure rates for patients with T1-2 (n = 8), T3 (n = 30), and T4 disease (n = 22) were 14.3%, 64.7%, and 87.9%, respectively (p < 0.05). A multivariate analysis of esophageal failure with descriptive variables of T classification, tumor length, and performance of intraluminal RT revealed that only T classification was an independent factor (p = 0.021). Two-year lymph node failure rates were 24.8% and 33.6% for patients with N0 (n = 36) and N1 disease (n = 24), respectively (p = 0.0035). Lymph node failure in N0 patients was found exclusively outside the treatment field. These results suggest that inclusion of potential lymph node metastases in the radiation field could lessen the lymph node failure rate in T1-3N0M0 patients.

Aged↗
PubMed1998

Phase-Contrast Tomographic Imaging Using an X-ray Interferometer.

Apparatus for phase-contrast X-ray computed tomography using a monolithic X-ray interferometer is presented with some observational results for human breast tissues. Structures characteristic of the tissues were revealed in the phase-contrast tomograms. The procedure of image analysis consists of phase retrieval from X-ray interference patterns and tomographic image reconstruction from the retrieved phase shift. Next, feasibility of phase-contrast imaging using a two-crystal X-ray interferometer was studied aiming at in vivo observation in the future. In a preliminary study, the two-crystal X-ray interferometer was capable of generating fringes of 70% visibility using synchrotron X-rays.

Journal Article↗
PubMed1998

Development of a two-dimensional imaging system for clinical applications of intravenous coronary angiography using intense synchrotron radiation produced by a multipole wiggler.

A two-dimensional clinical intravenous coronary angiography system, comprising a large-size view area produced by asymmetrical reflection from a silicon crystal using intense synchrotron radiation from a multipole wiggler and a two-dimensional detector with an image intensifier, has been completed. An advantage of the imaging system is that two-dimensional dynamic imaging of the cardiovascular system can be achieved due to its two-dimensional radiation field. This world-first two-dimensional system has been successfully adapted to clinical applications. Details of the imaging system are described in this paper.

Journal Article↗
PubMed1998

Medical applications with synchrotron radiation in Japan.

In Japan, various medical applications of synchrotron X-ray imaging, such as angiography, monochromatic X-ray computed tomography (CT), radiography and radiation therapy, are being developed. In particular, coronary arteriography (CAG) is quite an important clinical application of synchrotron radiation. Using a two-dimensional imaging method, the first human intravenous CAG was carried out at KEK in May 1996; however, further improvements of image quality are required in clinical practice. On the other hand, two-dimensional aortographic CAG revealed canine coronary arteries as clearly as those on selective CAG, and coronary arteries less than 0.2 mm in diameter. Among applications of synchrotron radiation to X-ray CT, phase-contrast X-ray CT and fluorescent X-ray CT are expected to be very interesting future applications of synchrotron radiation. For actual clinical applications of synchrotron radiation, a medical beamline and a laboratory are now being constructed at SPring-8 in Harima.

Journal Article↗
PubMed1998

Phase-contrast X-ray CT image of breast tumor.

Phase-contrast X-ray CT images generated by differences in refractive indices can be used to visualize the internal structures of soft tissues without contrast enhancement. In this study, imaging of human breast tumor was performed on formalin-fixed samples. Experiments were carried out at the synchrotron source of the Photon Factory, Tsukuba, Japan. The X-ray energy was adjusted to 17.7 keV. Phase-contrast X-ray CT images revealed various structures of human breast tumor as clearly as optical images.

Journal Article↗
PubMed1998

High-spatial-resolution and real-time medical imaging using a high-sensitivity HARPICON camera.

A HARPICON(TM) camera has been applied to a digital angiography system with fluorescent-screen optical-lens coupling. It uses avalanche multiplication in the photoconductive layer for high-sensitivity imaging. The limiting spatial resolutions in the 1050 scanning-line mode of the camera are about 30 and 50 micro m at input field sizes of 20 x 20 and 50 x 50 mm on the screen, respectively. For high-speed imaging, the 525 scanning-line mode at a rate of 60 images s(-1) can be selected. High-quality images of coronary arteries in dogs were obtained by intra-aortic coronary angiography and superselective coronary angiography using a single-energy X-ray above the iodine K-edge energy.

Journal Article↗
PubMed1998

Tc-99m diethylenetriamine pentaacetic acid (DTPA)-human serum albumin (HSA) radionuclide lymphography for detecting the location of chyluria.

The cause of chyluria cannot be easily detected by CT scan or other imaging methods, except conventional lymphography, but Tc-99m diethylenetriamine pentaacetic acid radionuclide lymphography clearly revealed the location of chyluria in the left renal pelvic area. Radionuclide lymphography is one of the choices in investigating chyluria due to its noninvasive and simple technique.

Aged↗
PubMed1998

Mature teratoma of the posterior mediastinum.

The vast majority of germ cell tumors in the thorax arise at or near the thymus. We report a case of a 41-year-old man with mature teratoma of the posterior mediastinum. He was asymptomatic and was incidentally found to have a posterior mediastinal mass. Computed tomography was helpful in suggesting a diagnosis of mature teratoma by demonstrating the presence of fat and calcification. The differential diagnosis included neurogenic tumors, liposarcoma, and extramedullary hematopoiesis.

Adult↗
PubMed1998

Slightly flexed knee position within a standard knee coil: MR delineation of the anterior cruciate ligament.

The purpose of this study was to assess the value of positioning the knee slightly flexed within a standard MR knee coil in delineation of the anterior cruciate ligament (ACL). Within the confined space of a commercially available knee coil, knee could bend as much as 30 degrees , average 17 degrees of flexion. Sets of oblique sagittal MR images were obtained at both fully extended and slightly flexed positions. Twenty-two normal knees and 18 knees with ACL tears were examined and paired MR images were evaluated by two observers. Compared with knee extension, the MR images for knee flexion provided better clarity in 57 % of reviews of full length of the ACL and 53 % of the femoral attachment. In the extended position the anterior margin of the ligament was obscured due to partial averaging with the intercondylar roof. We recommend examining the knee in an achievable flexed position within the standard knee coil.

Adolescent↗
PubMed1998

Well-differentiated liposarcoma of the retroperitoneum with a fat-fluid level: US, CT, and MR appearance.

We report a case of retroperitoneal liposarcoma with a fat-fluid level that has not been previously described. A 36-year-old man presented with abdominal distension. Ultrasonography, CT, and MR imaging showed a tumor with a fat-fluid level; nondependent fluid was characteristic of fat. Liposarcoma should be included in the differential diagnosis of tumors exhibiting a fat-fluid level.

Adipose Tissue↗