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M Akisada

Publications and source records attributed to M Akisada.

At least 19 recordsLinked to original sources
PubMed1992

Phosphorus-31 nuclear magnetic resonance study on the effects of endurance training in rat skeletal muscle.

To evaluate changes in muscle energetics following endurance training, we measured phosphorus-31 nuclear magnetic resonance (31P NMR) spectra on rat muscle in vivo before and after training in the same animals. The endurance training lasted for 3 months. The 31P NMR spectra were obtained serially at rest, during exercise by electrical stimulation, and during recovery. Intramuscular phosphocreatine (PCr), inorganic phosphate (P(i)), adenosine 5'-triphosphate (ATP) and pH were determined from the NMR spectra. The ratio of PCr:(PCR + P(i) at rest showed no difference between the trained and control groups even after 3 months of training. During exercise, however, this ratio was significantly higher in the trained group than in the control group. The ratio also recovered more rapidly after exercise in the trained group. The intramuscular pH decreased slightly by approximately 0.1 pH unit during exercise but did not show a significant difference between the groups. These results indicated that endurance training of 3 months duration improved the ATP supply system in the muscle. They also demonstrated that 31P NMR is a potent method for evaluating the effects of training in the same individuals.

Adenosine Triphosphate↗
PubMed1992

User requirements and standards for PACS. 2nd Japan-Nordic PACS Symposium.

PACS has been regarded as a system which will bring a new era to image handling, radiology departments and its services to other departments of the hospital. However, many recently held international conferences indicate that a worldwide consensus on 'what is PACS, why is PACS needed and who is PACS for' has not been established. Although the actual PACS implementation will vary among the countries and according to each situation, a worldwide consensus of PACS should be possible. This would help those involved to speed up the implementation of PACS. It is suggested that this consensus needs to be developed by convergence of three points of view; the availability, maturity and cost of the technologies on which PACS is built, the user requirements for PACS and standardization in PACS. These themes were the topics of the 2nd Japan-Nordic PACS Symposium which was arranged in Tampere, Finland, June 9-11th 1991. A summary of the papers and discussions of the symposium is produced in this paper.

Cost-Benefit Analysis↗
PubMed1992

User and manufacturer's requirements for IMAC standardization in Japan.

Many radiologists and radiological technologists understand that Picture Archiving and Communication Systems (PACS) are useful not only for image management but also for improving the quality of patient care. However, such systems have not yet been widely installed in hospitals. In order to determine why radiologists have not installed a PACS in their hospitals, we carried out a written survey of 400 Japanese hospitals asking them to describe the current image management activities, the problems inherent in PACS and the problems related to standardization. 216 hospitals responded, and the following suggestions were compiled concerning possible improvements to PACS. (1) PACS benefit needs to be improved with respect to patient care. (2) The cost of PACS should be reduced. (3) The system should be easier to operate and should save time. (4) Standardization is needed to allow simplified, cost-effective networking. We also carried out a written survey of 25 PACS and related equipment manufacturers asking them to describe the opinions inherent in current PACs and the problems related to standardization. Ten manufacturers responded, and the various suggestions were compiled concerning possible improvements to the PAC system.

Japan↗
PubMed1992

Left atrial function in ischemic heart disease assessed by intravenous digital subtraction angiography.

To investigate changes in left atrial morphology and dimensions during the cardiac cycle, the atrium was visualized by intravenous digital subtraction angiography (DSA). The study subjects consisted of 22 male patients whose average age was 54.5 +/- 8.6 years. They had ischemic heart disease without mitral valve disease and were in sinus rhythm. They were 11 patients with old myocardial infarction (OMI group) and 11 who had chest pain without evidence of infarction (AP group). DSA was performed in the continuous mode. Contrast material (35 ml) was injected at a rate of 18 ml/sec via a catheter in the superior vena cava and subtraction images were obtained at a speed of 30 frames/sec in the right anterior oblique projection. The left atrial and left ventricular margins were traced manually, their areas were calculated, and fractional changes in area were analyzed. The left ventricular ejection fraction (LVEF) was calculated by densitometry. Cardiac catheterization was performed in 16 patients and the left ventricular end-diastolic pressure (LVEDP) and mean pulmonary arterial wedge pressure (PAWP) were measured. The entire left atrium was clearly imaged using DSA. Phase analysis of the time-area curves in the right anterior oblique projection revealed that the left atrial area was maximal during left ventricular end-systole (%LA1 = 100%), it decreased during early left ventricular diastole (%LA2), and then increased slightly again during mid-diastole (%LA3). After left atrial contraction, the minimum area was obtained (%LA4). The left atrium showed a two-stage decrease in the area due to passive emptying and active contraction during left ventricular diastole. Passive emptying (%LA1-%LA2) was significantly less in the OMI group than in the AP group (6.3 +/- 3.6 vs 13.3 +/- 4.8%, p < 0.01, respectively). In all 22 subjects, passive emptying correlated with LVEF (r = 0.70, p < 0.001) and LVEDP (r = -0.58, p < 0.05). There was no difference in active contraction (%LA3-%LA4) between the 2 groups (26.0 +/- 5.7% in the OMI group, 28.2 +/- 8.4% in the AP group), and it did not correlate with LVEF or LVEDP. The ratio of passive emptying to active contraction [(%LA1-%LA2)/(%LA3-%LA4)] correlated with LVEF (r = 0.63, p < 0.01). These findings suggested that impaired left ventricular diastolic function and a relative increase in atrial contraction were present in patients with a lower LVEF. The %LA4 correlated with LVEDP and PAWP (r = 0.65, r = 0.63, p < 0.01, respectively). In conclusion, DSA proved to be a useful method for investigating left atrial morphology and function.

Aged↗
PubMed1991

Tears of cruciate ligaments and menisci: evaluation with cine MR imaging.

A cine magnetic resonance (MR) imaging technique, involving the acquisition of kinematic sagittal images during knee movement, was used to evaluate 52 symptomatic knee joints. Results were compared with those obtained by means of static three-dimensional (3D) MR imaging. Twenty-seven of the 28 anterior cruciate ligament (ACL) tears and 22 of 24 normal ligaments were correctly identified at cine MR imaging for a sensitivity of 96% and a specificity of 92%. Static 3D MR imaging yielded a sensitivity of 71% and a specificity of 88%. All four posterior cruciate ligament tears were identified at cine and 3D MR imaging. For meniscal tears, cine MR imaging yielded a sensitivity of 48% and a specificity of 96%; the sensitivity and specificity for 3D MR imaging were 71% and 96%, respectively. Cine MR imaging proved to be more useful than static MR imaging in assessing the tightness of cruciate ligaments, especially of those that were partially torn, and in assessing the movement of meniscal-free fragments. The increased information obtained with cine MR imaging may warrant continued investigation and clinical application.

Adult↗
PubMed1991

Early skin reaction following superficial proton irradiation.

Balb/c mice were irradiated on the leg in the area of the spread out Bragg peak (SOBP) of a 30 MeV proton beam. The proton beam was modulated to different ranges in order to determine the early skin reaction versus beam quality at different portions of the SOBP. The respective 50% moist desquamation doses of 1, 3, and 8.5 mm penetration were 25.9, 30.0, and 30.4 Gy. Irradiation of the superficial layer with the distal portion of the SOBP produced a significantly more severe reaction than did whole layer irradiation.

Animals↗
PubMed1990

[A case of double primary malignancy of intracranial germinoma and thymoma controlled by radiotherapy].

We report a case of double primary malignancy, in which intracranial germinoma and thymoma occurred successively and independently. As curative therapies, the former lesion was treated by definitive irradiation and the latter by postoperative irradiation. Excellent local control has been maintained for 79 and 49 months, respectively, since the beginning of the radiotherapy. The accumulated dose to the thoracic spinal cord was 63.5 Gy. No symptoms suggesting the onset of radiation myelopathy, the most critical late radiation injury, have been observed up to now. We also investigated radiobiological effect to the spinal cord assessed by the formulae of CRE and TDF.

Adult↗
PubMed1990

[Radiation tolerance of partially irradiated liver in a multidisciplinary treatment for hepatoma].

Radiation tolerance of the partially irradiated liver was studied in eight patients with primary hepatoma treated by a multimodal approach. Seven patients were treated by transarterial embolization therapy (TAE) with Lipiodol-MMC, and two patients were treated by operation, combined with radiotherapy. Six patients had liver cirrhosis and the other one had renal dysfunction. Respiration-gated irradiation was employed to reduce a treatment volume for seven patients. Radiation portals were carefully tailored using the embolized Lipiodol or a metal clip inserted into the tumor as references. Two or three portals were used for each patient. The treatment volume ranged from 64 to 1400 cm3. The target dose ranged from 50.4 Gy to 81.0 Gy, from 73.5 to 108.6 in TDF. Liver function tests (GOT, GPT, LDH, ALP, ChE and total Bilirubin) were examined for 30 weeks after initiation of irradiation. Three patients showed abnormal value in more than 5 tests. Of these three patients, the hepatic hilum was included in the treatment volume in two, and the tumor progressed during the observation period in two. Leukopenia and thrombopenia were observed, but these values were not below 2000 and 40000/mm3, respectively, although the thrombocyte count before irradiation was below 100000/mm3 in 7 patients. AFP titers decreased after the treatment in six out of seven patients with abnormally elevated pretreatment titer. The survival period after staring irradiation was 6.5 to 25 months. "The volume dose" did not correlate well with the degree of the liver function aggravation.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1990

Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition.

The effect of muscle hypertrophy on the relationship between magnetic resonance (MR) relaxation time and muscle fibre composition was investigated. Relaxation time and muscle fibre composition were measured in five subjects before and after a 20-week period of strength training. Muscle fibre composition in all subjects exhibited a significant shift to a predominance of fast-twitch (FT) fibres as a result of 20-week strength training (% area FT fibres: mean values from 49.8%, SD 17.9% to 57%, SD 5.6%; P less than 0.05). Longitudinal relaxation time (T1) and transverse relaxation time (T2) were prolonged significantly after strength training (T1 mean values from 334.9 ms, SD 13.6 to 359.0 ms, SD 9.0, P less than 0.001; T2 from 27.5 ms, SD 0.9 to 30.8 ms, SD 2.3, P less than 0.05). A constant relationship was observed in changes caused by strength training in muscle fibre composition (% area FT) and relaxation time, with a high correlation obtained between both parameters. These results indicate that MR relaxation time can be used for non-invasive estimation of muscle fibre composition.

Adult↗
PubMed1990

Moving knee joint: technique for kinematic MR imaging.

A system for magnetic resonance imaging of the knee joint during movement was developed by using a gating system and cine acquisition. The technique was used in 10 subjects: five with no history of knee pain or injury and five with tears of the anterior cruciate ligament. The normal ligaments and menisci appeared as low-intensity structures against intermediate-intensity hyaline cartilage. The ligament tears appeared discontinuous and faint against the background of the to-and-fro moving joint fluid.

Adult↗
PubMed1990

New trend of cardiac imaging--intravenous coronary arteriography by synchrotron radiation.

Synchrotron radiation is a broadspectrum intense X-ray beam. Selected X-ray wavelength was obtained by Bragg reflex. That is a monochromatic beam, which has a high spatial resolution, and has a K-edge discontinuity in attenuation coefficient, which, by energy subtraction, contributes to improve time resolution. An attempt to apply this method to intravenous coronary arteriography was performed in 7 anesthetized dogs. The beam was obtained by synchrotron radiation from accumulation ring, was reflected by silicon crystal, and was detected by 7 inch image intensifier system. Two-dimensional real time images were recorded on video tape. Phantom experiment was also performed. In dogs, coronary arteries were clearly distinguished by synchrotron radiation, especially at real time by video system. Phantom experiment suggested that coronary arteries could be visualized even over the visualized left ventricle. In conclusion, synchrotron radiation using two-dimensional real time images is expected to be useful in intravenous coronary arteriography in man.

Animals↗
PubMed1990

Evaluation of exercise muscle energetics by NMR.

Magnetic resonance imaging (MRI) is superior to ultrasonography and X-CT especially in density resolution in soft tissue. 31P NMR provides information on metabolism, which has not been obtained in vivo by conventional methods, such as phosphocreatine (PCr), inorganic phosphate (Pi), ATP, and intracellular pH. We used MRI and 31P NMR spectroscopy to study skeletal muscle metabolism of human and rat. These NMR results suggested that 1) estimation of muscle fiber composition, 2) evaluation of muscle ATP turnover and 3) imaging of local muscle fatigue are possible.

Animals↗
PubMed1990

The role of preoperative radiotherapy for invasive thymoma.

Six patients with large invasive thymomas were treated by preoperative irradiation with 12 to 20 Gy before total or partial resection of the tumor. The responses of these 6 thymomas were estimated on the chest radiograms as follows; complete response in 2 patients, partial response in 3 and no response in one. Although the clinical responses varied, the surgical specimens of all the tumors pronounced severe fibrosis, probably not related to irradiation, and necrotic foci with a few viable tumor cells. Total resection of the thymoma was performed in 3 patients and subtotal resection in 3. Adhered or involved surrounding tissues such as the pericardium, pleura and/or veins were also resected in most patients. Preoperative radiotherapy facilitated total or subtotal resection of the invasive thymoma mass by reducing the tumor volume.

Adult↗
PubMed1990

[MR imaging of the arm].

Thirty arms of healthy adults were studied with MR imaging using surface coil. Fine structures of the arm, such as muscular bundles, small vessels and nerves were clearly demonstrated. Deep fascia dividing muscular bundles appeared as high intensity on T1-weighed image due to fat deposition beneath the fascia. Aponeurosis is also flat sheet of densely arranged collagen fibers. With rather thicker layer of collagen fibers than fascia, aponeurosis appeared as low intensity sheet that was frequently demonstrated on MR images of the extremities.

Adult↗
PubMed1989

[Pulmonary infarction associated with bronchogenic carcinoma].

Pulmonary infarction may be associated with bronchogenic carcinoma. Radiopathological correlation was performed in four patients. There were two cases of squamous cell carcinoma, one case of adenocarcinoma and one case of large cell carcinoma. Infarcts in patients with squamous cell carcinoma were obscured on plain radiographs by a large primary tumor or atelectasis of the affected lobe. Infarcts in adenocarcinoma and large cell carcinoma were clearly demonstrated on plain radiographs; 1 to 2 cm in size, round or polygonal in shape, blurred in margin, and located at the periphery of the same lobe as the primary tumor. Rapid appearance of infarcts was helpful in distinguishing from intrapulmonary metastasis. Invasion of the pulmonary artery, pulmonary vein and bronchial wall in hilar region was thought to be responsible for pulmonary infarction. Pulmonary infarct should be considered in patients with centrally invasive bronchogenic carcinoma, when a small ill-defined opacity appears at the periphery of the involved lobe over a short period.

Aged↗
PubMed1989

[Field localization and verification system for proton beam radiotherapy in deep-seated tumors].

It has been recognized that, for precise localization and verification of radiation fields, a marking drawn on the skin surface is not entirely reliable because its position relative to bony structures or internal organs is not stationary. This is especially true when treating deep-seated tumors located below the clavicle. In proton beam radiotherapy at the University of Tsukuba, we ristrict the margins around the target volume. Therefore, special care in field localization and verification is needed, and we make it a rule to take X-ray pictures on each treatment day. To accomplish this, we have developed a localize-and-verify system by using fluoroscopic techniques and combining it with a real-time digital image processing device. This allows for the formation of a digital image of the proton field and storage it in the optic disc. By using this system as well as verification films, filed placement errors were measured in 10 patients with deep-seated tumors. Out of a total of 190 localizations, 22% exhibited a field placement error of more than 5 mm, where patient positioning and field localization were done by using skin drawings aligned with laser beams. This result strongly suggests the necessity for daily localization and verification of radiation fields, as is being done by us, for precision in the execution of proton beam radiation therapy.

Adult↗
PubMed1989

Intense accumulation of indium-111 leukocytes in peritonitis carcinomatosa.

In order to detect the infectious foci in a case of terminal recurrent cancer of the sigmoid colon with intense inflammation, In-111 oxine leukocyte scintigraphy was performed. Leukocytes labeled with In-111 oxine quickly localized within the region of peritonitis carcinomatosa and could be imaged after 4 hours. With time, high activity appeared in this area. And 48 hours after injection, the large intestine was clearly seen. However, no activity was seen in the main recurrent tumor. This suggested that the labeled leukocytes had accumulated in regions of inflammation rather than in malignant tissue. When performing In-111 leukocyte scintigraphy for diseases in which tumor cells and inflammation are mixed, distinguishing the two components is particularly important, and time-sequential scanning is very useful.

Adenocarcinoma, Papillary↗