PubMed Health⌕ Search

Biomedical subjects

M Zuguchi

Publications and source records attributed to M Zuguchi.

At least 19 recordsLinked to original sources
PubMed2005

FFT analysis of the X-ray tube voltage waveforms of high-frequency generators for radiographic systems.

PURPOSE: To present a novel method for analyzing the voltage waveform from high-frequency X-ray generators for radiographic systems. MATERIAL AND METHODS: The output signal of the actual voltage across the tube of a high-frequency generator was measured using the built-in voltage sense taps that are used for voltage regulation feedback in X-ray generators. The output signal was stored in an analyzing recorder, and the waveforms were analyzed using FFT analysis. The FFT analysis of high-frequency generators consisted of obtaining the power spectrum, comparing the major frequency components in the tube voltage waveforms, and examining the intensity of each frequency component. RESULTS: FFT analysis enables an objective comparison of the complex tube voltage waveforms in high-frequency X-ray generators. FFT analysis detected the change in the X-ray tube voltage waveform that occurred when there were problems with the high-frequency generator. CONCLUSION: High-frequency X-ray generators are becoming the universal choice for radiographic systems. The X-ray tube voltage and its waveform are important features of an X-ray generator, and quality assurance (QA) is important, too. As a tool for engineers involved in the design and development of X-ray generators, we can see that our methods (FFT analysis) might have some value as a means of describing generator performance under varying conditions. Furthermore, since the X-ray tube voltage waveform of a high-frequency generator is complex, FFT analysis may be useful for QA of the waveform.

Algorithms↗
PubMed2005

Feasibility of rapid-sequence 31P magnetic resonance spectroscopy in cardiac patients.

PURPOSE: To determine the clinical feasibility of rapid-sequence phosphorus-31 magnetic resonance spectroscopy (31P-MRS) of the heart with cardiac patients using a 1.5T clinical MR system. MATERIAL AND METHODS: Twenty cardiac patients, i.e. dilated cardiomyopathy (DCM) 13 cases, hypertrophic cardiomyopathy (HCM) 3 cases, hypertensive heart diseases (HHD) 3 cases, and aortic regurgitation (AR) 1 case were examined using rapid cardiac 31P-MRS. Complete three-dimensional localization was performed using a two-dimensional phosphorus chemical-shift imaging sequence in combination with 30-mm axial slice-selective excitation. The rapid-sequence 31P-MRS procedure was phase encoded in arrays of 8 x 8 steps with an average of 4 acquisitions. The total examination time, including proton imaging and shimming, for the rapid cardiac 31P-MRS procedure, ranged from 10 to 15 min, depending on the heart rate. Student's t test was used to compare creatine phosphate (PCr)/adenosine triphosphate (ATP) ratios from the cardiac patients with those of the control subjects (n = 13). RESULTS: The myocardial PCr/ATP ratio obtained by rapid 31P-MRS was significantly lower (P < 0.001) in DCM patients (1.82 +/- 0.33, mean +/- SD), and in patients with global myocardial dysfunction (combined data for 20 patients: 1.89 +/- 0.32) than in normal volunteers (2.96 +/- 0.59). These results are similar to previous studies. CONCLUSION: Rapid-sequence 31P-MRS may be a valid diagnostic tool for patients with cardiac disease.

Adenosine Triphosphate↗
PubMed2004

Rapid-sequence phosphorus-31 magnetic resonance spectroscopy of the human heart using a 1.5-T clinical system.

PURPOSE: To compare a 'standard' slow phosphorus-31 magnetic resonance spectroscopy (31P-MRS) sequence with two faster sequences in phantoms and healthy volunteers using a 1.5-T clinical system. MATERIAL AND METHODS: Complete 3D localization was performed using a 2D phosphorus chemical-shift imaging sequence in combination with 30-mm axial slice-selective excitation. Two 31P-MRS rapid sequences (RS8-4: 8 x 8 phase-encoding, with an average of 4 acquisitions, and RS16-1: 16 x 16 phase-encoding, 1 acquisition) were compared with the standard sequence (StdP: 16 x 16 phase-encoding, with an average of 8 acquisitions) in phantom and healthy volunteers. RESULTS: Acquisition time for the 31P-MRS procedure with StdP, RS8-4, and RS16-1 in the healthy volunteer studies ranged from 30 to 45, 3 to 5, and 3 to 5 minutes, respectively. Metabolite measurements of healthy volunteers obtained from 31P-MRS using RS8-4 correlated with values obtained using StdP (PCr r2=0.63, P<0.001; ATP r=0.41, P<0.01 and PCr/ATP ratio r2=0.25, P<0.05). There was no correlation between StdP and RS16-1 for either ATP or the PCr/ATP ratio (r2=0.03, P=0.60, and r2=0.11, p=0.26, respectively). Reproducibility (intensity of phosphorus signal) with RS16-1 was worse than that of RS8-4 or StdP. CONCLUSION: 31P-MRS using RS8-4 may be a valid diagnostic tool for patients with cardiac diseases.

Adult↗
PubMed2001

Bronchial artery aneurysm treated with percutaneous transluminal coil embolization.

We present a case with asymptomatic mediastinal bronchial artery aneurysm at the origin of the left bronchial artery. This bronchial artery aneurysm was successfully treated with percutaneous transluminal coil embolization. Complete embolization of the feeding artery and tributaries from the aneurysm is the key to successful isolation of a large bronchial artery aneurysm from the circulation. Percutaneous transluminal embolization is one of the treatment options for a patient with asymptomatic, incidentally-identified bronchial artery aneurysm.

Aneurysm↗
PubMed2001

Cine viewing of abdominal CT.

A few studies have been reported that CT cine viewing on the CRT is superior to film-based viewing of CT images (Seltzer et al., Radiology 197 (1994) 119; Bonaldi et al., Am. J. Roentgenol. 170 (1998) 373; Tillich et al., Am. J. Roentgenol. 169 (1997) 1611). The purpose of our study is to know how to use cine viewing of abdominal CT. Thirty CT studies on the abdomen with both precontrast and postcontrast images were examined. The suitable rate of cine viewing ranged from 1 to 6 frames per second according to the size, the contrast and the complexity of the anatomical structures, and the slice thickness. For small or complex structures, checking each image might be required to know the full detail of them. Positional sorting among multiphase images, which is followed by consecutive display of a precontrast image, postcontrast early and late phase images at one position and so on, is useful to see the dynamic pattern of enhancement of the anatomical structures. However, there was no significant difference between cine viewing and film-based viewing concerning both the detectability of the anatomical structures and the conspicuity of enhancement of the liver and the pancreas, so that cine viewing might be an alternative to film-based viewing for CT diagnosis of the abdomen.

Abdomen↗
PubMed2000

Relationship between the pixel value in digital subtraction angiography and iodine concentration: study in high iodine concentration with original phantom.

Quantitative digital subtraction angiography (DSA) image analysis based on densitometry is widely accepted and used. For the densitometoric DSA image analysis, it is required that there is a linear relationships between the pixel values on DSA images (DSA values) and contrast medium iodine concentration or the thickness of the vessels or the chambers filled with contrast material. We studied on relationship between the DSA value and iodine concentration especially in high iodine concentration. As for the relationship between DSA values and iodine concentration on the DSA images at low concentration, DSA phantom had a good linear relationship. However, the relationship at the high iodine concentration, DSA phantom sometimes lost this linear relationship. Our results suggested that it was necessary to identify relationship between DSA values and iodine concentration in each DSA system, especially in high iodine concentration setting, for densitometoric DSA image analysis.

Angiography↗
PubMed1999

[Acquired pulmonary stenosis caused by mediastinal mature teratoma: a case report].

A 13-year-old girl was admitted with a sudden onset of chest oppression. Mediastinal teratoma was suspected on chest X-ray and CT scan. A grade 2/6 systolic murmur was heard at the upper left sternal area and cardiac catheterization showed mild pulmonary stenosis. After resection of the tumor, the murmur disappeared and histopathological diagnosis was mature teratoma. This is a rare case report of pulmonary stenosis caused by mediastinal mature teratoma.

Adolescent↗
PubMed1998

[Percutaneous transcatheter coil embolization of the patent ductus arteriosus for elderly patient with left ventricular disfunction].

We performed the coil embolization for 64-year-old male with patent ductus arteriosus and left ventricular dysfunction. We used "snare method" and "cross catheter technique" delivering one coil transvenously and one coil transarterially. Echocardiograms at 7 month after the procedure demonstrated complete occlusion of the ductus, though small shunt was detected at discharge.

Catheterization, Peripheral↗
PubMed1997

Stent angioplasty for renovascular disease associated with acute aortic dissection.

Aortic replacement was performed in a patient with acute type A aortic dissection originating from the descending thoracic aorta. Postoperatively, a persistent false lumen resulted in severe stenosis of the right renal artery. Percutaneous stent angioplasty improved renovascular hypertension and renal function. This procedure is useful for management of patients with branch complications of aortic dissection.

Aortic Dissection↗
PubMed1997

[Cine display of postprocessed 3D MR images of the thoracic aorta].

We have developed a cine display of postprocessed 3D MR images of the thoracic aorta. Maximum intensity projection (MIP) images of the thoracic aorta in each phase were reconstructed from consecutive 2D-cine MR data sets, and displayed in a cine loop. The postprocessed 3D MR images clearly showed the relationship between major cervical branches and aortic pathologies such as aneurysms, and cine display presented the flow pattern in the aorta. 3D-cine MR angiography seems to be useful for follow-up studies of thoracic aortic diseases especially in patients with renal dysfunction.

Adult↗
PubMed1996

Coronary angioplasty ameliorates hypoperfusion-induced endothelial dysfunction in patients with stable angina pectoris.

OBJECTIVES: This study sought to investigate the effect of coronary angioplasty on chronic hypoperfusion-induced endothelial dysfunction in patients with coronary heart disease. BACKGROUND: The endothelium is an important component for organ flow regulation. Ischemia with or without reperfusion is known to cause endothelial dysfunction. We tested the hypothesis that chronic hypoperfusion impairs endothelial function in the angiographically normal coronary artery segment distal to stenosis and that the impairment by chronic hypoperfusion is reduced by coronary angioplasty. METHODS: In 13 patients with stable angina pectoris, substance P (10, 30 and 100 pmol) and nitroglycerin (200 micrograms) were sequentially infused into the coronary artery in a cumulative manner on the day after coronary angioplasty. In 10 of these patients, vascular responses to these agents were again investigated 3 months after angioplasty. Changes in vascular diameter were evaluated in vessels located proximal and distal to the target lesion, both of which were angiographically normal, by performing computer-assisted quantitative coronary angiography. In five patients, the transstenotic pressure gradient was also measured with a pressure sensor-mounted guide wire before angioplasty. RESULTS: On the day after angioplasty, the magnitude of dilation by substance P in distal segments was significantly less than that in proximal segments and inversely correlated with the transstenotic pressure gradient (p < 0.05) and lesion stenosis (p < 0.05). There was no difference in nitroglycerin-induced vasodilation between the two vessel segment groups. Three months later, the impaired response to substance P in the distal segment was restored to normal. CONCLUSIONS: We conclude that chronic hypoperfusion impairs endothelium-dependent dilation of coronary artery distal to critical stenosis in patients with ischemic heart disease and that coronary angioplasty ameliorates the endothelial dysfunction within 3 months.

Aged↗
PubMed1996

[MR imaging of carbon monoxide intoxication: evaluation of 13 cases to discuss the relation between MR findings and clinical course].

MR images of the brain were retrospectively reviewed in 13 patients with carbon monoxide (CO) poisoning to examine the relation between the MR findings and clinical course. The patients included 11 men and 2 women whose ages ranged from 6 to 88 years (mean, 38 years). Repeated MR studies of at most five times were performed on 9 patients. Lesions in the bilateral globus pallidi were found in 5 cases showing hyperintensity on T2-weighted images (T2WI) and iso-to hypointensity on T1-weighted images (T1WI). The patients with only pallidi lesions clinically recovered well. Hyperintense white matter lesions were recognized on T2WI in 8 patients, including all 5 with delayed encephalopathy. Sequential studies generally showed a tendency of regression of these hyperintense lesions with improvement of symptoms, indicative of reversible demyelination as documented in the pathological literature. One patient with poor prognosis revealed white matter lesions, that were hyperintense on T2WI and very hypointense on T1WI, which may represent irreversible change. Thus, clinical course seems to be closely related with white matter lesions, but not with pallidi lesions. In cases of CO intoxication, therefore, MR study provides valuable information on patients' clinical prognoses.

Adolescent↗
PubMed1995

A simple maneuver in follow-up digital subtraction angiography for multiple coronary-aorta bypass grafts.

A simple maneuver in intraarterial digital subtraction angiography (DSA) is proposed to improve the images of left internal thoracic artery bypass grafts (LITAGs). A contrast flush in the left subclavian artery, using a catheter that had been percutaneously introduced from the left brachial artery, was carried out in 14 patients with multiple coronary-aorta bypass grafts (CABGs) after aortic DSA. The side-hole portion of the catheter tip was positioned in the proximal left subclavian artery as the coiled portion remained in the aortic arch. Nonionic contrast medium (350 mg/ml of iodine) was injected with an automatic injector in a volume of 6-8 ml and at a flow rate of 3-4 ml/sec. Left subclavian arterial flush DSA delineated the LITAGs excellently in 11, well in 3, and fairly or poorly in none of the 14 cases. There were no complications in any of these cases. A supplemental contrast flush of the left subclavian artery with a pigtail catheter following aortic DSA improves the diagnosis of multiple CABG patency.

Aged↗
PubMed1994

[CT and MR imaging findings of sphenoidal masses].

CT and MR imaging findings of 57 sphenoidal masses were retrospectively reviewed to assess the possibility of differential diagnosis between them. Various kinds of masses such as pituitary adenoma, epipharyngeal cancer, mucocele, chordoma, chondroma, chondrosarcoma, distant metastasis, multiple myeloma, fibrous dysplasia, craniopharyngioma, hemangiopericytoma, giant cell tumor, primary sphenoidal cancer, malignant melanoma, leukemia, histiocytosis X, and giant cell tumor were included in this series. CT scanning was performed in all cases, while MR images were obtained in 48 cases using a spin-echo pulse sequence. The relative density of the masses, bony changes and calcification were evaluated on CT, and on MR images, signal intensity of the masses relative to the normal gray matter, contrast enhancement and extension/contour were evaluated. Although no single feature appeared to be specific to the masses, detection of calcification on CT, identification of the normal pituitary gland as deformed or displaced on T1-weighted images, signal intensity on T2-weighted images, and extension of the masses seemed to be useful and should be examined in terms of their ability to assist in differential diagnosis. Finally, accommodative classification of sphenoidal masses primarily based on presumed origin or mode of extension was attempted.

Adolescent↗
PubMed1993

[Right ventricular endomyocardial biopsy from the femoral vein].

Several methods are used for percutaneous right ventricular endomyocardial biopsy, including the subclavian venous approach, internal jugular venous approach and femoral venous approach. The femoral venous approach is the most suitable for routine cardiac catheterization, but the risk of right bundle branch block may be increased because the specimens often must be taken from a high position in the right ventricle. We modified the femoral venous approach using King's biotome, and obtained adequate tissue specimens in 14 cases without any complications. We reformed the tip of the biotome into an inverted S shape by scrubbing with the thumb, and we reformed the tip of the long sheath (Cordis) into a J shape by warming with steam, for easy introduction of the biotome and safe biopsy. We describe here the methodological details of our technique.

Biopsy↗
PubMed1993

Cranial MRI and MR angiography in Menkes' syndrome.

We report two boys with Menkes' syndrome who underwent cranial MRI and MR angiography (MRA). In both, CT and MRI revealed progressive cerebral atrophy with a subdural haematoma or effusion. Delayed myelination or dysmyelination of the white matter was suggested. Tortuosity of the cervical and intracranial vessels was well demonstrated by MRA, obviating more invasive conventional angiography should it be thought necessary to demonstrate the characteristic systemic vascular changes of this syndrome.

Atrophy↗