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T Ishiguchi

Publications and source records attributed to T Ishiguchi.

At least 37 records · Page 2Linked to original sources
PubMed2000

An experimental teleradiology transmission system using a high-speed ATM backbone network.

We evaluated the performance of an experimental teleradiology system based on a high-speed ATM backbone network. Image acquisition, transmission and the disk-to-display processing times were measured. Computerized tomography (CT) scans printed on 14 inch x 17 inch (36 cm x 43 cm) films were digitized and transferred over the network. The average time for the entire process was 1 min 30 s. Three radiologists interpreted 20 cases. For CT image interpretation, the reading time for one case ranged from 2 to 12 min (mean 6 min 46 s) on a monitor, and from 1 to 3 min (mean 1 min 31 s) with the original film. The ATM backbone network operating at 156 Mbit/s provided sufficient speed for remote consultation. However, further improvements in the operability of the system, especially the image viewing station, are necessary before it will be satisfactory for clinical use.

Computer Systems↗
PubMed2000

[Study on evaluation method of patient dose in diagnostic radiology required for introducing the guidance level: investigation of entrance surface dose of patient using direct measurement by TLD].

Using direct measurement, we investigated entrance surface doses of patients for routine radiographs in attempt to develop evaluation methods of patient dose in order to establish the guidance level in Japan. To date, patient doses have been evaluated by calculations based on radiographic conditions, or model experiments using phantoms. Their patient doses are then evaluated based on several assumptions. Direct measurement of patient dose is difficult to perform in many patients due to its time requirement, level of expertise required and difficulty in providing an explanation of the procedure to the patient. However, such direct measurement is essential since it incorporates all aspects of radiography from the radiographic equipment used, to the actual conditions of each patient without assumption. In this study, we examined the (1) need for introducing the guidance level, (2) controversial points in the calculation method for patient dose evaluation, (3) evaluation accuracy required for introducing the guidance level, and (4) necessity for a standardized method.

Guidelines as Topic↗
PubMed2000

MR imaging of the enlarged endolymphatic duct and sac syndrome by use of a 3D fast asymmetric spin-echo sequence: volume and signal-intensity measurement of the endolymphatic duct and sac and area measurement of the cochlear modiolus.

BACKGROUND AND PURPOSE: In enlarged endolymphatic duct (EED) and sac (EES) syndrome, deformity of the EED and EES is congenital; however, hearing loss is acquired. To investigate the pathophysiology of progressive sensorineural hearing loss in EED and EES syndrome, we measured the volume of the EED and EES, the diameter of the EED and EES, the area of the cochlear modiolus, and the signal intensity of the EES and compared our findings against degree of hearing loss. METHODS: Thin-section MR images of 33 ears in 17 patients with EED and EES syndrome were studied. All studies were obtained on a 1.5-T MR unit using a quadrature surface phased-array coil. Heavily T2-weighted 3D fast asymmetric spin-echo images were obtained with a voxel size of 0.3 x 0.3 x 0.8 mm without zero-fill interpolation. Two radiologists traced the areas of the EED and EES manually, and the volume was calculated. The area of the cochlear modiolus, diameter of the EED and EES, and signal intensity of the EES were also measured by drawing regions of interest manually. The signal intensity ratio of EES/CSF was calculated. These measured values were compared against audiographic data, and the degree of linear correlation was determined. RESULTS: The volume of the EED and EES, the area of the modiolus, the diameter of the EED and EES, and the signal intensity of the EES did not show significant correlation with degree of hearing loss. CONCLUSION: These findings suggest that there is a microscopic area of damage or fragility in the inner ear not visible even with thin-section heavily T2-weighted MR imaging.

Adolescent↗
PubMed2000

[Radiation exposure to patient and radiologist during transcatheter arterial embolization for hepatocellular carcinoma].

PURPOSE: To evaluate radiation exposure to patients and radiologists during transcatheter arterial embolization(TAE) for hepatocellular carcinoma. MATERIALS AND METHODS: In 39 TAE procedures performed at eight institutes, skin doses were evaluated with thermoluminescence dosimeters at the patient's back(entrance surface) and lower abdomen, and at the radiologist's forehead and abdomen. Real-time dosimeters were also used to evaluate patient skin dose. RESULTS: The patients' mean entrance surface dose was 973 +/- 681 mGy(range, 185 to 3543 mGy) with the mean fluoroscopic time of 21 minutes and 6 digital subtraction angiography(DSA) acquisitions. The dose at the patients' lower abdomen was 0.98 +/- 0.77 mGy. Doses for the radiologists were 0.04 +/- 0.04 mGy at the forehead and 0.15 +/- 0.19 mGy and 0.005 +/- 0.01 mGy at the abdomen over and under the apron, respectively. Fifty-six percent of the patients' skin dose was from DSA and 44% from fluoroscopy. CONCLUSIONS: Patient skin dose may occasionally exceed the dose for transient erythema. Because a patient may have repeated TAEs, skin doses or X-ray conditions should be recorded. The exposed doses of radiologists were considered to be acceptable with proper techniques. Further efforts to reduce radiation should be directed toward both DSA and fluoroscopy.

Aged↗
PubMed1999

Magnitude subtraction vs. complex subtraction in dynamic contrast-enhanced 3D-MR angiography: basic experiments and clinical evaluation.

Magnitude subtraction and complex subtraction in dynamic contrast-enhanced three-dimensional magnetic resonance (3D-MR) angiography were compared using a phantom and 23 human subjects. In phantom studies, complex subtraction showed far better performance than magnitude subtraction, especially for longer echo times, with thicker slices, and without fat suppression. With complex subtraction, non-fat-suppressed studies showed contrast-to-noise ratios comparable to those in fat-suppressed studies. In human subjects, complex subtraction was superior to magnitude subtraction in 9 subjects, but comparable to magnitude subtraction in 14 subjects. There were no cases in which magnitude subtraction was superior to complex subtraction. Although the differences observed in human studies when complex subtraction was applied with thinner slices, shorter echo times, and the fat-suppression technique were not as pronounced as those seen in phantom studies, complex subtraction should be performed in dynamic contrast-enhanced 3D-MR angiography because there are no drawbacks in complex subtraction. Further research is necessary to assess the feasibility of dynamic contrast-enhanced 3D-MR angiography without fat suppression in human subjects using complex subtraction, as suggested by the results of phantom studies. If it is found to be feasible, dynamic contrast-enhanced 3D-MR angiography without fat suppression using complex subtraction may prove to be a robust technique that eliminates the need for shimming and can reduce the acquisition time. J. Magn. Reson. Imaging 1999;10:813-820.

Adult↗
PubMed1999

Implantation of an endovascular covered stent-graft for distal aortic arch aneurysm via midsternotomy under pigtail catheter guidance.

We implanted an endovascular covered stent-graft for distal aortic arch aneurysm involving the left subclavian artery in 12 cases. A stent-graft was delivered just below the aneurysm via aortotomy with direct vision using a 12 F delivery sheath under guidance of a pigtail catheter placed via the groin artery. The proximal anastomosis of the stent-graft was performed with inclusion technique, and the aortotomy was then closed with it. This technique reduces operative damage by eliminating distal anastomosis and should reduce operative mortality and morbidity.

Adult↗
PubMed1999

Hereditary angioedema with gastrointestinal involvement: endoscopic appearance.

We present the first reported case of hereditary angioedema (HAE) with gastric involvement to be successfully evaluated by endoscopy both during and after an attack. A 31-year-old man who had a family history of angioedema was admitted to our hospital with complaints of abdominal pain and swelling of extremities. Computed tomography scan and endoscopy carried out during this attack revealed transient gastrointestinal wall edema which, along with decreased levels of serum C4 and C1 inhibitor, confirmed the diagnosis of HAE with gastrointestinal involvement. During the attack, the gastric mucosa was erythematous and edematous, and parts of its surface bulged into the gastric lumen, resembling a submucosal tumor, as a result of massive submucosal edema. During the healing process, a number of small nodules and raised erosions developed over the entire gastric mucosal surface after healing of prominent gastric edema. Within 55 days, the gastric mucosa had returned to normal. The endoscopic findings for the stomach in HAE have not, to our knowledge, been previously described.

Adult↗
PubMed1999

[Preprocedural and procedural imaging modalities for transluminally placed endovascular grafting].

The vascular system can be evaluated with computed tomography (CT), magnetic resonance angiography (MRA), angiography, and computer-based CT image processing systems before successful transluminally placed endovascular grafting (TPEG). Noninvasive modalities are useful, but angiography is mandatory to determine whether TPEG is indicated. During the procedure, fluorography with a wide-image intensifier and high-resolution digital subtraction angiography are known to be essential, but intravascular ultrasonography is also indispensable to achieve accurate TPEG.

Aortic Aneurysm↗
PubMed1998

Vena cava occlusion with balloon to control blood pressure during deployment of transluminally placed endovascular graft.

Transluminally placed endovascular graft (TPEG) replacement has been applied to treat various aortic diseases. At the moment of deployment, TPEG receives a pressure pulse force to shove it distally, which possibly results in misplacement. Moreover, deploying the TPEG in the aorta increases cardiac afterload, which may damage myocardial function. To avoid these risks, we developed a new technique to control blood pressure by almost complete venous return occlusion. Two occlusion balloon catheters are inserted into the superior and inferior vena cava via the femoral vein. TPEG is deployed at the proper position during inflation of the vena cava balloon to maintain a blood pressure as low as 60 mm Hg by cardiac preload blockage. We, thus far, have not experienced even a trivial sequela with this technique.

Aortic Diseases↗
PubMed1997

[A case of the tuberculous abscess in the abdominal wall].

A case of the tuberculous abscess in the abdominal wall is reported. A 84-year-old female was admitted to our hospital with evaluation of soft tumor at the left lower abdomen. She has a mass in the abdominal wall measuring 4 cm in diameter, and abscess in the abdominal wall was detected by ultrasonogram and CT. The confirmed diagnosis of abdominal wall tuberculosis was made by means of bacterial culture and polymerase chain reaction (PCR method) of the aspirated fluid from a mass. Multiple calcified lesions on the abdominal X-ray were seen, which were thought to past history of tuberculous peritonitis. Antituberculosis therapy of three-drug regimens was not effective. Four month later, resection of the abscess was then performed. Adhesion was demonstrated between greater omentum and peritoneum, therefore the abscess in the abdominal wall was considered to arise and advance directly from the abdominal cavity.

Abdominal Muscles↗
PubMed1997

Endovascular stenting of a traumatic dissecting aneurysm of the extracranial internal carotid artery--case report.

A 57-year-old male presented with a traumatic dissecting aneurysm of the distal, extracranial internal carotid artery (ICA). Stent placement resulted in complete occlusion of the aneurysm and preservation of the carotid blood flow. He also had an atherosclerotic stenosis of the ipsilateral middle cerebral artery, which was uneventfully treated by angioplasty 3 months after stent placement. Endovascular reconstruction of the ICA with a stent may be the best way to occlude dissecting aneurysms, especially in patients who cannot tolerate ICA occlusion, are at risk from delayed ischemia, or have wide-necked or multiple aneurysms.

Aortic Dissection↗
PubMed1996

Selective fallopian tube catheterisation in female infertility: clinical results and absorbed radiation dose.

Clinical results of fluoroscopic fallopian tube catheterisation and absorbed radiation doses during the procedure were evaluated in 30 infertility patients with unilateral or bilateral tubal obstruction documented on hysterosalpingography. The staged technique consisted of contrast injection through an intrauterine catheter with a vacuum cup device, ostial salpingography with the wedged catheter, and selective salpingography with a coaxial microcatheter. Of 45 fallopian tubes examined, 35 (78%) were demonstrated by the procedure, and at least one tube was newly demonstrated in 26 patients (87%). Six of these patients conceived spontaneously in the follow-up period of 1-11 months. Four pregnancies were intrauterine and 2 were ectopic. This technique provided accurate and detailed information in the diagnosis and treatment of tubal obstruction in infertility patients. The absorbed radiation dose to the ovary in the average standardised procedure was estimated to be 0.9 cGy. Further improvement in the X-ray equipment and technique is required to reduce the radiation dose.

Adult↗
PubMed1996

Palliative therapy using polyurethane-covered self-expandable metallic stents for malignant esophageal strictures: experiences in six patients.

To evaluate the utility and limitations of palliative stenting with polyurethane-covered self-expandable metallic stents, 6 patients (3 males and 3 females ranging in age from 58-85 [mean 72.1] years) with malignant esophageal strictures were treated with these stents between April 1993 and October 1995. Three had esophageal carcinoma, two had gastric carcinoma and one had lung carcinoma. Song-type self-expandable metallic stents were inserted by intubation under local laryngeal anesthesia. A retriever was attached in 4 stents and an anti-reflux mechanism was attached in 2 stents placed over the esophagocardiac strictures. The stents were placed successfully in all patients, and no major complication related to intubation was encountered. All the stents fully expanded within 3 days after insertion. The grade of dysphagia was improved in 5 (83%) of the 6 patients. One stent was extracted using a retriever in one patient with no improvement. No reflux symptoms were observed in 2 patients whom received stents with an anti-reflux mechanism. No blockage of the stent due to food impaction or secondary stricture occurred in any patient during the observation period. One stent migrated into the stomach in one patient 27 days after insertion. Esophageal stenting with polyurethane-covered self-expandable metallic stents is a relatively safe and effective palliation for malignant esophageal strictures.

Aged↗
PubMed1996

[Fundamental study for lung-cancer screening by helical CT. First report: evaluation of radiation dose and image quality using a phantom].

In a fundamental study on the early detection of lung cancer by helical computed tomography (CT), we evaluated the effect of scanning parameters on radiation dose and image quality using a phantom. The exposure dose at the center of the gantry and the absorbed dose at the center of an acrylic phantom changed linearly in proportion to tube current. On the other hand, as the table feed speed increased, the rate of reduction in these doses became smaller. While the change in CT value of an acrylic sphere in the longitudinal axis, the difference in CT value between an acrylic sphere and styrofoam in the horizontal plane and the CT profile curve of an acrylic sphere in the horizontal plane did not change according to tube current, an increase in table feed speed brought about the degradation of these items. In conclusion, reduction of the tube current in helical scanning is able to reduce radiation dose without causing a significant change in image quality, but an excessive increase in table feed speed does not reduce radiation dose effectively and is associated with degradation in image quality.

Humans↗
PubMed1995

[CT findings of mass-forming pancreatitis: correlation with histopathologic findings].

We attempted to analyse the computed tomographic (CT) characteristics of mass-forming pancreatitis. Thirty inflammatory masses were studied using the combined method of dynamic CT (Dy-CT) and high dose enhancement CT (HD-CT) with a thin-section scan. From the correlation between the CT enhancement effect and the histopathologic changes, injury of the glandular element and proliferation of fibrous tissue were more prominent in inflammatory masses showing a different enhancement effect from the surrounding pancreatic parenchyma. In addition to these changes, constriction of the intrapancreatic artery caused a poor enhancement effect on Dy-CT, whereas marked round cell infiltration with lymphoid follicle formation increased the enhancement effect on HD-CT. This combined CT method is valuable for the diagnosis of mass-forming pancreatitis and adequately reflects its histopathologic condition.

Adult↗
PubMed1995

[Interventional radiology: current and future].

The current status and the future development of interventional radiology in Japan were reviewed and discussed. The recent development of interventional radiology has been supported by the technological advances in medical imaging modalities, catheters or other devices. Superselective catheterization and embolization of small vessels have been realized by digital subtraction angiography and microcatheters. Intravascular occlusion with detachable coils is an effective treatment for cerebral aneurysms. Results of balloon angioplasty for arterial occlusive disease have been promoted with the use of vascular stents. Stent-grafts for the treatment of aortic aneurysms are under clinical trials in the western countries. New devices such as specially designed balloons for local drug delivery, angioscopic catheters, intravascular ultrasound and atherectomy catheters are now clinically used. Micromachine technologies will also be applied for new therapeutic catheters. In the field of non-vascular interventional radiology, the use of open-magnet MRI and real-time MR fluoroscopy will be useful in lesion localization, needle tracking and monitoring of treatment such as interstitial laser irradiation, radio frequency tumor ablation or ethanol injection. Interventional radiology will be more widely accepted for the treatment of vascular and non-vascular diseases in the future.

Catheterization↗
PubMed1993

[Kinetics of flomoxef sodium monitored with in vivo 19F NMR spectroscopy].

The potential usefulness of in vivo 19F NMR spectroscopy for the monitoring of flomoxef sodium (FMOX) kinetics was evaluated. In the experimental study using phantom the minimum concentration of FMOX of which signals could be monitored with 19F NMR spectroscopy was 16 micrograms/ml. In patients with intravenous bolus injection and drip infusion of FMOX (2 g/100 ml), signals from normal heart, liver, and kidney were clearly monitored with 19F NMR spectroscopy. In normal lung any signal was not detected, but in a lung with a cancer associated massive atelectasis the monitoring of signals was possible with 19F NMR spectroscopy in both intravenous and intraarterial injections. Monitoring of FMOX kinetics with in vivo 19F NMR spectroscopy will be useful in clinical applications.

Cephalosporins↗