Biomedical subjects

Kenya Murase

Publications and source records attributed to Kenya Murase.

60 records · Page 4Linked to original sources

PubMed2002

Renal uptake rate measurement of 99m Tc-dimercaptosuccinic acid using spectral analysis.

We developed a new method for measuring the rate of renal uptake of 99mTc-dimercaptosuccinic acid (DMSA) using spectral analysis. The renal uptake rate (per minute) of DMSA (K) was calculated by averaging the tissue impulse response function values obtained by spectral analysis between 10 min and 15 min. The K values obtained by spectral analysis correlated well with the renal uptake rates (%) measured 2h after DMSA administration (r=0.921 with background correction; r=0.924 without background correction). There was a good agreement between the K values obtained by spectral analysis using the kidney time-activity curves with (x) and without (y) background correction (r=0.993, y=1.089x+0.004), suggesting that our method requires no background correction. There was excellent correlation between the K values obtained by spectral analysis using the kidney time-activity curves with (y) and without (x) kidney depth correction (r=0.992, y=1.721x+0.000 with background correction; r=0.990, y=1.720x+0.000 without background correction), suggesting that our method requires no kidney depth correction. These results indicate that spectral analysis is appropriate and useful for the quantification of renal uptake rate of DMSA. We believe that this method will facilitate even more widespread utilization of the quantitative assessment of DMSA uptake by planar scintigraphy, since it needs only 10-15 min for imaging, and background and kidney depth correction and blood sampling are not required.

Female↗

PubMed2002

Pulsating renal blood flow distribution measured using power Doppler ultrasound: correlation with hypertension.

Arterial compliance is associated with the first stage of hypertension and atherosclerosis. We propose here a compliance index, which measures pulsating renal blood flow distribution using a power Doppler ultrasound (US). We assessed the relationship between the compliance index and blood pressure and between the compliance index and risk factors of atherosclerosis. The subjects consisted of 136 consecutive patients (96 males, 40 females) who underwent a physical checkup. Ages ranged from 40 to 60 years with a mean of 50.1 years. Patients with past renal disease and/or renal dysfunction were excluded. Using a power Doppler US combined with an ECG-gated and echo-tracking system, we recorded the vascular distribution of the renal parenchyma at 8 to 10 time points during an interval of the R wave of the ECG. Using a color pixel counting technique, we calculated the area (A) corresponding to the colored vascular distribution at power Doppler US. The relationships between A and the time points (t) were fitted to a quadratic equation. The compliance index of renal parenchymal vessels was obtained by twice differentiating the quadratic equation obtained above (d2A/dt2), and taking the result as a new hemodynamic index. In the univariate correlation analysis, the compliance index was correlated with age (r=-0.26, p=0.002), systolic blood pressure (r=-0.33, p=0.0001), diastolic blood pressure (r=-0.45, p<0.0001), serum uric acid (r=-0.28, p=0.001), and body mass index (r=-0.32, p=0.0002). On the multivariate stepwise regression analysis, the compliance index was significantly correlated with diastolic blood pressure (beta=-0.36, p<0.0001) and body mass index (beta=-0.18, p<0.0001). In conclusion, the compliance index is a candidate for a new hemodynamic marker of renal blood flow abnormality caused by hypertension.

Adult↗

PubMed2002

Quantitative evaluation of mean transit times obtained with dynamic susceptibility contrast-enhanced MR imaging and with (133)Xe SPECT in occlusive cerebrovascular disease.

OBJECTIVE: We report on quantitative mean transit time images obtained using dynamic susceptibility contrast-enhanced MR imaging after an IV bolus injection of a contrast agent. Our study compared cerebral hemodynamics measured using dynamic susceptibility contrast-enhanced MR imaging with the cerebral perfusion reserve obtained using dynamic (133)Xe single-photon emission computed tomography (SPECT). SUBJECTS AND METHODS: Seventeen patients with chronic cerebral artery occlusion or stenosis diagnosed by digital subtraction angiography were examined. Dynamic susceptibility contrast-enhanced MR imaging data were acquired using a multishot echoplanar sequence. Our procedure for quantification of mean transit time was based on the indicator dilution theory and deconvolution analysis. RESULTS: The increased mean transit time values obtained with dynamic susceptibility contrast-enhanced MR imaging correlated well (r=-0.789, p < 0.0001) with decreased cerebral perfusion reserve determined by performing dynamic (133)Xe SPECT before and after administration of acetazolamide. The mean transit time values in the regions with severely decreased perfusion reserve were significantly higher than those in the regions with normal or moderately decreased perfusion reserve (p < 0.0001 and p = 0.0004, respectively). CONCLUSION: Mean transit time images generated from dynamic susceptibility contrast-enhanced MR imaging data could be used to evaluate the extent of cerebral perfusion reserve impairment in patients with occlusive cerebrovascular disease.

Aged↗

PubMed2002

[Measurement of left ventricular chamber and myocardial volume in hypertrophic cardiomyopathy patients by ECG-gated myocardial perfusion SPECT: application of a newly developed edge-detection algorithm].

Quantitative gated SPECT (QGS) software has been reported to demonstrate inaccurate edge detection in the left ventricular chamber in hypertrophic cardiomyopathy patients. In this study we developed a method to calculate left ventricular volume (LVV) and left myocardial volume (LMV) from gated SPECT data using a newly developed edge-detection algorithm, and we compared it with the QGS method of calculating LVV and LMV in a phantom study. Our method gave more accurate measurements LVV and LMV whereas the QGS method underestimated LMV. Compared with QGS LVV and LMV, our method yielded better results in the phantom study.

Algorithms↗

PubMedDate not supplied

Measurement of tumor blood flow using dynamic contrast-enhanced magnetic resonance imaging and deconvolution analysis: a preliminary study in musculoskeletal tumors.

OBJECTIVE: To measure tumor blood flow (TBF) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). METHODS: A DCE-MRI was performed using inversion recovery-preparation fast-field echo sequences. Dynamic data were obtained every 3.2 seconds for 2 minutes, immediately after gadolinium injection. In 14 patients with malignant musculoskeletal tumors, TBF maps were generated pixel-by-pixel by deconvolution analysis. For preclinical studies, muscle blood flow in 5 volunteers and signal intensities of different gadolinium concentrations were measured. RESULTS: There was a good linear relationship between signal intensities and gadolinium concentrations (r = 0.989, P < 0.001, at gadolinium concentrations <or=2 mmol/L). The average value of muscle blood flow in volunteers was 11.1 +/- 2.7 mL.100 mL.min. In 14 patients with musculoskeletal tumors, TBF showed wide variances: the lowest of 9.6 mL.100 mL.min in liposarcoma and the highest of 182.0 mL.100 mL.min in osteosarcoma. After chemotherapy, the TBF values (7.9, 11.0, and 11.7 mL. 100 mL.min) in the good responders were lower than those (26.8, 31.0, and 62.4 mL.100 mL.min) in the poor responders. CONCLUSIONS: A functional map of TBF generated by DCE-MRI and deconvolution analysis would be a promising tool for evaluating tumor blood flow in vivo.

Adolescent↗

PubMedDate not supplied

Assessment of left ventricular volumes using multi-detector row computed tomography (MDCT): phantom and human studies.

PURPOSE: Multi-detector row CT (MDCT) is a new noninvasive modality for coronary artery imaging. Using the same MDCT data obtained for coronary artery assessment, left ventricular (LV) volumes such as end-diastolic (ED) and end-systolic (ES) volumes (EDV and ESV, respectively) and ejection fraction (EF) can potentially be assessed when ED and ES datasets are extracted. The purpose of this study was to evaluate the feasibility of MDCT in the assessment of LV volumes. METHODS: Using a pulsating heart phantom (EDV = 143 ml, ESV = 107 ml, stroke volume = 36 ml, EF = 25%) and MDCT, EDV and ESV were measured and EF was calculated. Clinical materials consisted of 11 consecutive human subjects who underwent MDCT. MDCT data were acquired during a single breathhold, using an intravenous injection of contrast medium. Left ventriculography (LVG) was performed in all patients as a gold standard. LV-EF was calculated by measuring ESV and EDV in all patients. RESULTS: In the phantom study, LV volumes were: EDV = 137 ml, ESV = 101 ml, stroke volume = 36 ml, and EF = 26%. Close correlations were observed between MDCT values and LVG values (EDV: r = 0.95, ESV: r = 0.98, EF: r = 0.93, p < 0.001). CONCLUSION: MDCT was useful for th e assessment of LV volumes and EF in various patients with CVD.

Adolescent↗