Biomedical subjects

Kiyoshi Murata

Publications and source records attributed to Kiyoshi Murata.

At least 19 recordsLinked to original sources

PubMed2007

Magnetic resonance voiding cystourethrography for vesicoureteral reflux.

PURPOSE: To assess the feasibility of magnetic resonance voiding cystourethrography (MRVCUG) using MR fluoroscopy for evaluation of vesicoureteral reflux (VUR), and its use as a noninvasive alternative to standard VCUG. MATERIALS AND METHODS: A total of 22 MR studies of 16 patients (five months to 41 years old) with primary VUR diagnosed by standard VCUG were evaluated. Six patients underwent MR studies and standard VCUG pre- and postoperatively. MR fluoroscopy was executed with a non-enhanced heavily T2-weighted single-shot fast spin-echo (FSE) sequence. The MR findings were correlated with those obtained by the gold standard, standard VCUG. RESULTS: Of the 44 kidney-ureter units, 20 were refluxing on MRVCUG and 21 were refluxing on standard VCUG. There were one false-positive and two false-negative units. MRVCUG was 90% sensitive with a specificity of 96% for detecting VURs that were calculated based on kidney-ureter units. Two false-negative units were found in mild cases (grade I and II). For the units of grade III, IV, and V (high-grade reflux), MRVCUG detected all of the refluxing renal collecting systems. CONCLUSION: MRVCUG can demonstrate high-grade reflux without ionizing radiation or catheterization.

Adolescent↗

PubMed2007

Multidetector-row computed tomography coronary angiography: optimization of image reconstruction phase according to the heart rate.

BACKGROUND: To optimize the image reconstruction phase of multidetector-row computed tomography (MDCT) coronary angiography according to the heart rate is crucial. METHODS AND RESULTS: Scan data were reconstructed for 10 different phases in 58 sequential patients who underwent 8-row cardiac MDCT. The obtained images were scored and compared in terms of motion artifacts and visibility of the vessels, and moreover, ECG record-based evaluations were added for clarification of the temporal relationships among these 10 phases. In the cases with lower heart rates (<65 beats/min), the best quality images were obtained when the end of the image reconstruction phase was positioned at the peak of the P wave. In some cases with higher heart rates (>65 beats/min), they were obtained in the late systolic period. CONCLUSION: As the heart rate increased, the optimal image reconstruction phase changed from mid diastole to late systole. However, it is recommended to try to decrease the heart rate of patients before data acquisition.

Aged↗

PubMed2006

Preparation of PEG-conjugated fullerene containing Gd3+ ions for photodynamic therapy.

A novel photosensitizer with magnetic resonance imaging (MRI) activity was designed from fullerene (C(60)) for efficient photodynamic therapy (PDT) of tumor. After chemical conjugation of polyethylene glycol (PEG) to C(60) (C(60)-PEG), diethylenetriaminepentaacetic acid (DTPA) was subsequently introduced to the terminal group of PEG to prepare PEG-conjugated C(60) (C(60)-PEG-DTPA). The C(60)-PEG-DTPA was mixed with gadolinium acetate solution to obtain Gd(3+)-chelated C(60)-PEG (C(60)-PEG-Gd). Following intravenous injection of C(60)-PEG-Gd into tumor-bearing mice, the PDT anti-tumor effect and the MRI tumor imaging were evaluated. The similar O(2)(*-)generation was observed with or without Gd(3+) chelation upon light irradiation. Both of the C(60)-PEG-Gd and Magnevist(R) aqueous solutions exhibited a similar MRI activity. When intravenously injected into tumor-bearing mice, the C(60)-PEG-Gd maintained an enhanced MRI signal at the tumor tissue for a longer time period than Magnevist(R). Injection of C(60)-PEG-Gd plus light irradiation showed significant tumor PDT effect although the effect depended on the timing of light irradiation. The PDT efficacy of C(60)-PEG-Gd was observed at the time when the tumor accumulation was detected by the enhanced intensity of MRI signal. This therapeutic and diagnostic hybrid system is a promising tool to enhance the PDT efficacy for tumor.

Animals↗

PubMed2006

Refraction contrast 11x-magnified X-ray imaging of large objects by MIRRORCLE-type table-top synchrotron.

The high-quality aspects of magnified X-ray images recorded using MIRRORCLE-6X are reported. MIRRORCLE-6X is inherently suitable for hard X-ray imaging owing to its magnified projection X-ray imaging, micrometre-size X-ray source point, wide radiation emission angle, X-ray spectrum ranging from 10 keV to 6 MeV, natural refraction contrast imaging and high flux output. Images produced with 11x geometrical magnification display a sharply enhanced edge effect when generated using a 25 microm rod electron target. Image contrast is enhanced 2x owing to refraction when compared with absorption contrast images. An imitation tumour implanted in a human chest phantom was made clearly visible by using edge enhancement on images. Soft tissue becomes highly visible as a natural consequence of refraction contrast when using hard X-rays for imaging. The authors believe that novel imaging provided by MIRRORCLE makes it a superior instrument for medical diagnosis.

Absorption↗

PubMed2006

Alcohol consumption and coronary artery calcium in middle-aged Japanese men.

Epidemiologic studies have investigated the relation between alcohol intake and coronary calcification, with controversial results. Furthermore, the influence of heavy drinking has not been well elucidated. In the present study, a random sample of community-based Japanese men aged 40 to 49 years without a history of cardiovascular disease (n=245) were examined for coronary artery calcium (CAC) determined by electron-beam computed tomography and drinking status. There was a J-shaped association between alcohol intake and CAC. There was an increase of CAC in heavy drinkers (>or=46 g/day), and participants who were drinking>or=69 g/day showed a significant increase in CAC compared with never drinkers after adjusting for other cardiovascular risk factors.

Adult↗

PubMed2006

CT-guided needle biopsy of lung lesions: a survey of severe complication based on 9783 biopsies in Japan.

PURPOSE: The aim of our study was to update the rate of severe complications following CT-guided needle biopsy in Japan via a mailed survey. MATERIALS AND METHODS: Postal questionnaires regarding CT-guided needle biopsy were sent out to multiple hospitals in Japan. The questions regarded: the total number and duration of CT-guided lung biopsies performed at each hospital, and the complication rates and numbers of pneumothorax, hemothorax, air embolism, tumor seeding, tension pneumothorax and other rare complications. Each severe complication was followed with additional questions. RESULTS: Data from 9783 biopsies was collected from 124 centers. Pneumothorax was the most common complication, and occurred in 2412 (35%) of 6881 cases. A total of 39 (35%) hospitals reported 74 (0.75%) cases with severe complications. There were six cases (0.061%) with air embolism, six cases (0.061%) with tumor seeding at the site of the biopsy route, 10 cases (0.10%) with tension pneumothorax, six cases (0.061%) with severe pulmonary hemorrhage or hemoptysis, nine cases (0.092%) with hemothorax, and 27 cases (0.26%) with others, including heart arrest, shock, and respiratory arrest. From a total of 62 patients with severe complications, 54 patients (0.55%) recovered without sequela, however one patient (0.01%) recovered with hemiplegia due to cerebral infarction, and the remaining seven patients (0.07%) died. CONCLUSIONS: This is the first national study documenting severe complications with respect to CT-guided needle biopsy in Japan. The complication rate in Japan is comparable to internationally published figures. We believe this data will improve both clinicians as well as patients understanding of the risk versus benefit of CT-guided needle biopsy, resulting better decisions.

Biopsy, Needle↗

PubMed2006

Pluronic F127: application in arterial embolization.

PURPOSE: Pluronic is a substance that is widely used in medical and pharmaceutical fields. In particular, 20% Pluronic F127 solution is a unique substance that is liquid at less than 15 degrees C and gelatinous at 25 to 60 degrees C. In this study, the authors took advantage of the gelation property of Pluronic F127 at human body temperature to simulate embolization and dissolution of the embolism in the renal artery and the superior mesenteric artery (SMA) using a rabbit model. MATERIALS AND METHODS: Four female Japanese rabbits (weight, 2.5-3 kg each) were used. The renal artery was fitted with a 4-F cobra-type catheter and embolized with a 20% Pluronic F127 solution at a temperature of 20 degrees C. The embolic effect was evaluated by angiography immediately after the initial injection and every 15 minutes for 2.5 hours after embolization. After 24 hours, pathologic changes of the renal parenchyma were also evaluated. The embolic effect for SMA and ischemic changes of the intestine were evaluated in the same manner. RESULTS: Angiographic findings showed that Pluronic F127 caused embolization immediately after injection and dissolved in the renal artery and the SMA after 90 to 120 minutes. The pathologic findings showed no ischemic change in the renal parenchyma. Necrosis was not found in the intestine, but focal hemorrhagic changes were extensively present when the gel had dissolved. This suggested that Pluronic F127 dissolved before severe tissue damage could occur. CONCLUSION: Pluronic F127 can potentially be used as a temporary embolic material.

Angiography↗

PubMed2006

[Plasma platinum concentration and anti-tumor effects after intra-arterial infusion of lipiodol-CDDP suspension evaluation with VX 2 rabbit liver cancer model and 7.0 Tesla MRI system].

To evaluate the usefulness of combination chemotherapy with cisplatin powder, which was newly designed for intra-arterial infusion (IA CALL) and lipiodol, for the VX 2 liver cancer model of the rabbit, sequential change of the plasma platinum concentration within the first 24 hours, as well as the tissue platinum concentration at 24 hours was measured after intra-arterial infusion of IA CALL. The infused materials were either IA CALL alone (C) or the combination of lipiodol+IA CALL (CL). In addition,the reduction rate of the VX 2 tumor was calculated among four therapeutic groups (C, CL, lipiodol alone (L), and saline alone (S)) after one week of intra-arterial infusion on the basis of 7.0 Tesla MR images. Total plasma platinum concentrations within the first 24 hours were kept low in group CL. No increase in the tissue platinum concentration in group CL was observed. On the other hand, the tumor reduction rate tended to be higher in group CL (group CL>group L=group C>group S). These results suggested that the intra-arterial infusion of IA CALL with lipiodol is more effective than that of IA CALL alone.

Animals↗

PubMed2005

MR imaging of the normal appendix and acute appendicitis.

PURPOSE: To describe the MR appearance of the normal appendix and the MR imaging characteristics of acute appendicitis with correlation to pathological severity. MATERIALS AND METHODS: A total of 20 volunteers participated in this study to demonstrate normal appendices by MR imaging. A total of 37 consecutive patients with clinically diagnosed acute appendicitis were also scanned. T1-weighted (T1WI) spin-echo images, T2-weighted (T2WI) fast spin-echo, and fat-suppressed spectral presaturation inversion recovery T2-weighted (T2SPIR) fast spin-echo images were obtained. The MR criteria for considering acute appendicitis were as follows: 1) thickening of the appendiceal wall with high intensity on T2WI or T2SPIR; 2) dilated lumen filled with high intensity material on T2WI or T2SPIR; and 3) increased intensity of periappendiceal tissue on T2WI or T2SPIR. RESULTS: The visibility of a normal appendix on MR imaging was 90% (18/20). It appeared as a cord-like structure of medium intensity without fluid collection in the lumen. A total of 30 cases with clinically diagnosed acute appendicitis had positive MR findings and all except one were pathologically proven. The one had cecal diverticulitis. These cases demonstrated filled lumen, with a hypointense wall on T1WI and slightly hyperintense on T2WI or T2SPIR. MR findings correlated well with pathological severity, especially a thicker wall, periappendiceal high intensity, and ascites were useful for suspecting severe appendicitis. CONCLUSION: Correct diagnosis of acute appendicitis was obtained with MRI, and correlated well with its pathological severity. MRI is a powerful alternative for diagnosing acute appendicitis especially for the patients in whom the radiation is major concern.

Acute Disease↗

PubMed2005

Percutaneous transluminal angioplasty for Brescia-Cimino hemodialysis fistula dysfunction: technical success rate, patency rate and factors that influence the results.

OBJECTIVE: To evaluate the initial clinical success and long-term patency rates of percutaneous transluminal angioplasty (PTA) using a venous approach for dysfunctional Brescia-Cimino fistula and to identify factors that may affect initial success and long-term patency. MATERIALS AND METHODS: A total of 99 PTA procedures were performed in retrograde fassion for 60 mature Brescia-Cimino shunts with dysfunction caused by anastomotic or peripheral outflow vein stenosis or occlusion. The initial clinical success rates were compared between stenosis and occlusion using Fisher's exact test. The Kaplan-Meier method was used to calculate the primary and secondary cumulative patency rates, and the log-rank test was used for comparison. Relative risks of patency loss according to clinical characteristics were determined with multivariate Cox models. RESULTS: The initial clinical success rate of all interventions was 92%, and the rates for stenosis and occlusion were 99 and 65%, respectively (P < 0.0001). The primary and secondary cumulative patency rates for fistulas (excluding initial failure) at 12 months were 53 and 84%, respectively. The relative risks were 5.2 (P = 0.004) for longer lesions and 4.5 (P = 0.007) for younger fistulas. The primary cumulative patency rate of four patients with a younger fistula and a longer stenosis at 4 months was 0%. CONCLUSION: Favorable primary and secondary cumulative patency rates are obtained in most patients. Long lesion length and younger age of fistulas were the two factors that reduced the patency rate after PTA.

Adult↗

PubMed2005

The first trial of phase contrast imaging for digital full-field mammography using a practical molybdenum x-ray tube.

RATIONALE AND OBJECTIVES: The image quality of a newly developed full-field digital phase contrast mammography (PCM) system and of a conventional screen-film (SF) mammography system were compared via images of a phantom and receiver operating characteristic (ROC) analysis of clinical images. METHODS: Magnified (1.75X) PCM images were scanned (sampling rate, 43.75 microm) and then reduced to original-sized, 25-micron pixel images printed on photothermographic film. Along with corresponding SF images, the phantom images were evaluated subjectively, and the clinical images of 38 patients were subjected to ROC analysis of mass and microcalcification. RESULTS: In the image quality of a phantom, the PCM exceeded the SF. In both mass and microcalcification, the ROC analysis Az values of the PCM clinical images surpassed those of the SF images. CONCLUSION: The PCM provides better images than the SF. Clinical trials suggest superior detection of both mass and microcalcification by full-field digital PCM over conventional SF mammography.

Breast Diseases↗

PubMed2005

Evaluation of treatment-induced cerebral white matter injury by using diffusion-tensor MR imaging: initial experience.

BACKGROUND AND PURPOSE: Treatment with chemotherapy and radiation therapy for brain tumors can cause white matter (WM) injury. Conventional MR imaging, however, cannot always depict treatment-induced transient WM abnormalities. We investigated the ability of diffusion-tensor (DT) MR imaging and proton MR spectroscopy to detect the treatment-induced transient changes within normal-appearing WM. METHODS: DT MR imaging and proton MR spectroscopy were performed in 8 patients treated with a combination of surgery, chemotherapy, and radiation therapy for brain tumors (17 examinations) and 11 age-matched controls. Apparent diffusion coefficient (ADC) value, fractional anisotropy (FA) value, and N-acetylaspartate (NAA)/creatine (Cr) ratio were obtained from 27 hemispheres with normal-appearing WM in the patients. We divided the datasets of isotropic ADC, FA, and NAA/Cr, on the basis of the time period after completion of radiation therapy, into 4 groups: group 1 (0-2 months; n = 10), group 2 (3-5 months; n = 5), group 3 (6-9 months; n = 7), and group 4 (10-12 months; n = 5). We compared averages of mean isotropic ADC, mean FA, and NAA/Cr of each patient group with those of the control group by using a t test. RESULTS: In the group 2, averages of mean FA and NAA/Cr decreased and average of mean isotopic ADC increased in comparison with those of the control group (P = .004, .04, and .0085, respectively). There were no significant differences in the averages between the control group and patient groups 1, 3, and 4. CONCLUSION: DT MR imaging and proton MR spectroscopy can provide quantitative indices that may reflect treatment-induced transient derangement of normal-appearing WM.

Adult↗

PubMed2004

Percutaneous vertebroplasty immediately relieves pain of osteoporotic vertebral compression fractures and prevents prolonged immobilization of patients.

To assess the immediate efficacy of percutaneous vertebroplasty (PVP) in relief of pain and improving mobility of patients with vertebral compression fractures (VCF) secondary to osteoporosis, 205 cases (175 patients) underwent 250 percutaneous injections of polymethylmethacrylate (PMMA; unilateral, 247 levels; bilateral, 3 levels) into vertebrae under CT and fluoroscopic guidance for 34 months. Patients were prospectively asked to quantify their pain on a visual analog scale (VAS) before and a day after PVP. The interval to mobilization was recorded in those who were immobilized because of pain and/or bed-rest therapy (115 cases). PVP was technically successful in all patients, with three cases of minimal complications. The mean VAS score available for 196 cases was improved from 7.22+/-1.89 (range, 3-10) to 2.07+/-1.19 (range, 0-10) by PVP. Ninety-four of 115 immobilized cases (81.7%) were mobile by 24 h after PVP, and the mean value was 1.9+/-2.8 days. The incidence of recurrent and new fractures was 15.6% in 4-25 months (mean, 15.3 months). PVP is a safe and effective treatment for relieving the pain associated with osteoporotic VCF and strengthening the vertebrae, avoiding refractures. This therapy leads to early mobilization and avoidance of the dangers of conservative therapy of bed-rest.

Aged↗

PubMed2004

Much lower prevalence of coronary calcium detected by electron-beam computed tomography among men aged 40-49 in Japan than in the US, despite a less favorable profile of major risk factors.

BACKGROUND: Since World War II (WWII), exposures to westernized lifestyle have occurred in many non-Western countries, including Japan. National surveys showed that risk factor profiles for atherosclerosis around 1990 were similar in men in the post WWII birth cohorts in the US and Japan. We compared the degree of coronary calcium and other factors in men in the post WWII birth cohort: men aged 40-49 in the US and Japan. METHODS: We conducted a cross-sectional study examining randomly selected 100 men from Kusatsu, Japan, and 100 men from Allegheny County, US. Coronary calcium was assessed using electron-beam computed tomography. RESULTS: Systolic blood pressure, total cholesterol, low density lipoprotein (LDL)-cholesterol, and smoking rates were higher among the Japanese (122.6 +/- 14.1 versus 113.7 +/- 9.6 mmHg, P < 0.01; 5.72 +/- 0.90 versus 4.99 +/- 0.81 mmol/l (220.9 +/- 34.6 versus 192.8 +/- 31.3 mg/dl), P < 0.01; 3.52 +/- 1.01 versus 3.10 +/- 0.78 mmol/l (136.0 +/- 39.0 versus 119.7 +/- 30.0 mg/dl), P < 0.01; and 48 versus 15%, P < 0.01, respectively). Triglycerides and fibrinogen were similar. High density lipoprotein (HDL)-cholesterol was higher among the Japanese. Body mass index, fasting insulin, and C-reactive protein were higher among the Americans. Prevalence of coronary artery calcium score >0 was strikingly lower among the Japanese than the Americans (13% versus 47%, P < 0.01). CONCLUSIONS: Much lower prevalence of coronary calcium despite a less favourable profile of many major independent risk factors in the Japanese might imply that there are strong protective factors against atherosclerosis in the Japanese. Further investigation is of critical importance.

Adult↗

PubMed2004

Diaphragmatic motion in the sitting and supine positions: Healthy subject study using a vertically open magnetic resonance system.

PURPOSE: To determine the postural difference of diaphragmatic motion between the sitting and supine positions. MATERIALS AND METHODS: A total of 10 healthy men were examined using a vertically open 0.5-T magnetic resonance (MR) system. A total of 40 sequential MR images were obtained in both the sitting and supine positions during two to five respiratory cycles. The diaphragmatic excursions (DEs) were measured on three diaphragmatic points of six sagittal planes for both positions. The differences in DEs between the anterior and posterior parts of the diaphragm were also determined. RESULTS: DEs in the supine position were significantly greater than those in the sitting position at 15 of the 18 points. In five of the six sagittal planes, the difference of DE between posterior and anterior points was significantly larger in the supine position than in the sitting position. CONCLUSION: Diaphragmatic movement in the supine position is greater than that in the sitting position, especially in the posterior part of the diaphragm.

Adult↗

PubMed2004

Prognostic value of ECG-gated thallium-201 single-photon emission tomography in patients with coronary artery disease.

BACKGROUND: The phenomenon of reversible impairment in LV function has been well described and is known as myocardial stunning. OBJECTIVE: Thallium-201 myocardial perfusion gated SPECT was used to evaluate myocardial stunning and its incremental prognostic value in patients with coronary artery disease. PATIENTS AND METHODS: Fifty-six patients (aged 63+/-11 years) with coronary artery disease were included in this study. All subjects underwent exercise thallium scintigraphy. ECG-gated SPECT was obtained both at post-stress (10 minutes after the injection of 111 MBq of thallium at the time of peak exercise) and at rest (180 minutes). The left ventricular ejection fraction (LVEF) and end-systolic and end-diastolic volume (ESV, EDV) were determined by a quantitative gated SPECT (QGS) program. RESULTS: Follow-up was complete in all patients (mean 569 days). The magnitude of the depression of post-stress LVEF relative to the rest LVEF was correlated with the severity of ischemia (p < 0.05). The group with a median LVEF of more than 45% had a significantly higher event-free rate (p < 0.01). CONCLUSION: Assessment of post-stress left ventricular function by gated-SPECT provides incremental prognostic information and is useful in predicting cardiac events in patients with suspected or definite coronary artery disease.

Causality↗

PubMed2004

Role of combined CT hepatic angiography and CT during arterial portography in the management of patients with hepatocellular carcinomas and liver metastases.

The purpose of this study was to evaluate the role of combined CT hepatic angiography (CTHA) and CT during arterial portography (CTAP) in the diagnosis and management of patients with hepatocellular carcinomas (HCC) and liver metastases. Fifty patients with HCC and 19 patients with liver metastases were referred for CTHA and CTAP prior to surgery or interventional therapy. Diagnosis was established by either surgery or clinical observation. Alterations of diagnosis and management resulting from CTHA and CTAP information were recorded. In patients with HCC, diagnosis was altered either by number, location or extent of lesions in 46% of patients and was 78% correct. Alterations of management were performed in 32% of the patients in total, and were correct in all but one. In patients with liver metastases, diagnosis was altered regarding either number, location or extent of lesions in 21% of patients and were 50% correct. Management was not altered after CTHA and CTAP in the patients with liver metastases. We conclude that CTHA and CTAP provide valuable clinical information for patients with HCC and significantly corrected their previous diagnosis and plans of management. CTHA and CTAP should be performed in patients with HCC when either surgical or interventional therapy is the treatment option.

Journal Article↗

PubMed2004

Visual assessment of coronary artery stenosis with electrocardiographically-gated multislice computed tomography.

BACKGROUND: With faster image acquisition times and thinner slice widths, multislice detector computed tomography (MSCT) allows visualization of human coronary arteries. Significantly improved image quality, with high resolution and new software for three-dimensional post-processing, has made noninvasive examination of the cavities within human body possible. OBJECTIVE: The aims of this study are to evaluate the diagnostic accuracy of ECG-gated MSCT for the detection of significant coronary artery stenosis and occlusions. METHODS: In 25 patients (19 male and 6 female aged 65+/-9 years) with suspected obstructive coronary artery disease, ECG-gated MSCT angiography was performed with an 8-slice MSCT scanner. Visual coronary arteries were simulated in three coronary arteries. Conventional coronary angiographies were performed in all patients. And coronary lesions in MSCT were estimated by two observers, who did not know the results of the coronary angiography. RESULTS: Current MSCT allows visual coronary artery with good image quality. The overall sensitivity for diagnosing significant coronary stenosis were 75.0%, the specificity was 95.6%. The positive and negative predictive values were 84.9 and 92.2%, respectively. The accuracy of MSCT for detecting coronary stenosis is the highest in the left main tranck and left anterior descending coronary artery, and lowest in the circumflex coronary artery. CONCLUSION: MSCT was feasible for the detection of coronary artery stenosis.

Adult↗