M Matsudaira

Kanazawa Medical University, Kanazawa, Ishikawa, Japan

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Publications (56)64.3 Total impact

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    ABSTRACT: The aims of this study were (1) to evaluate the effect of surrounding materials on the iterative reconstruction-based line-source response function (IR-RF) of (18)F, (11)C, (13)N, and (15)O using a preclinical PET system, and (2) to determine whether and how annihilation outside the source can be visualized experimentally. We performed all the measurements using the LabPET-8 PET/CT subsystem built-in the Triumph II platform (TriFoil Imaging, Inc., Northridge, CA, USA). IR-RF was measured for (18)F, (11)C, (13)N, and (15)O, and was expressed as full-width at half-maximum (FWHM) and full-width at tenth maximum (FWTM) using a glass capillary phantom mounted in materials of various densities, which were chosen to cover the wide range of real tissues. To determine whether and how annihilation outside the source can be visualized, we designed a concentric ring paper phantom, which consisted of a source at the center with 4 ring-like paper layers. When the radionuclides were placed in air (material density 0 g/cm(3)), IR-RFs were similar among the radionuclides tested. As the surrounding material density increased, IR-RFs for higher energy-emitting radionuclides ((11)C, (13)N, and (15)O) became worse, whereas those of (18)F remained relatively constant over the range of surrounding material densities (0-2.17 g/cm(3)). Both FWHM and FWTM values were closely correlated with mean energy of radionuclides at middle to high material densities (material density 0.94-2.17 g/cm(3)). The FWTM/FWHM ratio of high energy-emitting radionuclides such as (15)O increased as a function of material density, which was followed by subsequent decrease at high material densities (1.2-2.17 g/cm(3)). Using a concentric ring paper phantom, annihilations outside the source were visible and measurable. The innermost layer was visible with all radionuclides, whereas the outer layers only with high energy positron emitters. The results indicate that surrounding material affects IR-RF particularly for high energy positron emitters. Furthermore, annihilation outside the radio-active source can be visualized with some circumstances such as those seen with a concentric ring paper phantom.
    Annals of Nuclear Medicine 03/2014; · 1.41 Impact Factor
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    ABSTRACT: The purpose of this study was to investigate the accuracy of cardiac PET with post-injection transmission scans. We performed a phantom study using 18F solution as well as 13N-ammonia PET study of ten patients. The average activities of no myocardial defect phantom model were estimated, and myocardial defect sizes of 12 phantom models were measured by pre- and post-injection transmission methods at various 18F activities. In 13N-ammonia PET at rest and during adenosine triphosphate (ATP) stress studies, measured defect sizes were compared between both methods. The ratios of average activity estimated by both methods (post/pre value) were almost 1.00 at each 18F activity and segment. Measured defect sizes by both methods showed an excellent correlation with true defect sizes (r = 0.98, p < 0.01 for pre vs. true value: r = 0.98, p < 0.01 for post vs. true value). The mean absolute errors of measurements were minimal up to 3.5% LV, and were similar between both methods. In 13N-ammonia PET, measured defect sizes by both methods also showed a good correlation (r = 0.97, p < 0.01). The results indicate that cardiac PET imaging with post-injection transmission scan provides information on myocardial tracer activity as well as myocardial defect size as does conventional pre-injection transmission method.
    Annals of Nuclear Medicine 04/2005; 19(2):83-9. · 1.41 Impact Factor
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    ABSTRACT: Dual-isotope simultaneous acquisition single-photon emission computed tomography (DISA SPECT) with 18F-fluorodeoxyglucose (FDG) and (99m)Tc-sestamibi appears attractive for the detection of viable myocardium because it permits simultaneous assessment of glucose utilisation and perfusion. Another potential benefit of this approach is that the measurement of left ventricular (LV) function may be possible by ECG gating. The aim of this study was to test the hypothesis that both myocardial viability and LV function can be assessed by a single ECG-gated 18F-FDG/(99m)Tc-sestamibi DISA SPECT study, based on comparison with 18F-FDG/13N-ammonia positron emission tomography (PET) and magnetic resonance imaging (MRI) as reference techniques. Thirty-three patients with prior myocardial infarction underwent ECG-gated 18F-FDG/(99m)Tc-sestamibi DISA SPECT and 18F-FDG/13N-ammonia PET on a single day. Of these, 25 patients also underwent cine-MRI to assess LV function. The LV myocardium was divided into nine regions, and each region was classified as viable or scar using a semiquantitative visual scoring system as well as quantitative analysis. The global and regional LV function measured by gated SPECT was compared with the results of MRI. There was good agreement in respect of viability (90-96%, kappa 0.74-0.85) between DISA SPECT and PET by either visual or quantitative analysis. Furthermore, although both global and regional LV function measured by gated SPECT agreed with those by MRI, (99m)Tc-sestamibi showed a closer correlation with MRI than did 18F-FDG. In conclusion, ECG-gated DISA SPECT provides information on myocardial viability, as well as global and regional LV function, similar to that obtained by PET and MRI.
    European journal of nuclear medicine and molecular imaging 03/2005; 32(2):195-202. · 5.11 Impact Factor
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    ABSTRACT: Electrocardiographic gated 13N-ammonia positron emission tomography (PET) enables simultaneous assessment of myocardial blood flow and left ventricular (LV) function. The aim of this study was to assess the accuracy of gated 13N-ammonia PET for evaluating global and regional LV function in patients with coronary artery disease (CAD) in comparison with conventional left ventriculography (LVG). Fifty-four patients with CAD underwent gated 13N-ammonia PET and LVG. The LV end-diastolic and end-systolic volumes (LVEDV, LVESV) and ejection fraction (LVEF) by gated 13N-ammonia PET were calculated using Cedars-Sinai automated quantitative gated single photon emission computed tomography (QGS) and compared with those obtained by LVG. The regional wall motion (RWM) was visually scored, and compared with that on LVG. There were good correlations between the 2 methods for LVEF, LVEDV and LVESV (R=0.828, R=0.821 and R=0.874 respectively). The RWM assessed by gated 13N-ammonia PET also agreed well with that by LVG (complete agreement was 70.4%, kappa=0.58). Gated 13N-ammonia PET combined with QGS works reasonably well for the assessment of both global and regional LV function in CAD patients, although additional calibration may be necessary.
    Circulation Journal 03/2005; 69(2):177-82. · 3.58 Impact Factor
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    ABSTRACT: A 79-year-old man with unstable angina underwent an emergency coronary angiography, and percutaneous balloon angioplasty was performed for LCX. Left ventriculography showed hypokinesis in the posterior wall, inferior and apical wall immediately after the PCI therapy. The defects on 123I-BMIPP SPECT seen in the inferior, posterior and lateral wall were more extensive than those observed on 99mTc-MIBI SPECT, and a flow-fatty acid metabolism mismatch pattern was observed. The 18F-FDG PET showed reduced uptake in the lateral segment, although 13N-NH3 PET showed normal perfusion, and a reverse flow-glucose metabolism mismatch pattern was observed. Left ventriculography showed significant improve to normal contraction on the 3-month follow up, and there was not significantly reduced uptake in 99mTc-MIBI SPECT, 123I-BMIPP SPECT, 13N-NH3 PET or 18F-FDG PET.
    Annals of Nuclear Medicine 01/2004; 17(8):699-702. · 1.41 Impact Factor
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    ABSTRACT: Objectives: Recently, we have used animal and clinical PET for new drug research and development. In such clinical investigation, Good Manufacturing Practice (GMP) and Good Clinical Practice (GCP) regulations are required, and a series of the PET studies of FK960 [N-(4-acetyl-1-piperazinyl)-p-fluorobenzamide monohydrate], a novel antidementia drug, was examined for predicting accurate clinical dose. Methods: (1) Synthesis of [18F]FK960: We developed a rapid synthesis method and an automated apparatus, and constructed the quality control system which is applicable for GMP regulation. (2) Pharmacokinetics study of FK960 in monkey PET: [18F]FK960 was mixed with unlabeled FK960 in saline to administer at dose of 0.1 mg/kg and about 370 MBq for each monkey, and arterial blood samples were withdrawn during the study for metabolite correction. FK960 concentration in the brain was calculated in units of mol/l. (3) Pharmacokinetics study of FK960 in clinical PET: Three male normal volunteers underwent PET imaging for 6 h after oral administration of a mixture of [18F]FK960 (185 MBq) which was synthesized under GMP regulation and unlabeled FK960 (6 mg), and the concentration was also calculated in the similar manner to that of the monkey PET. Results: [18F]FK960 penetrated the blood–brain barrier and perfusion-dependently distributed in the whole brain. In the monkey study, maximal mean concentrations and time of maximal in brain were 1.11×10−7 mol/l (M) and 3.0 h, respectively. On the other hand, the mean concentration in the human brain was highest (2.73×10−7 M) at 1.67 h and was 1.82×10−7 M at 6 h after administration, both of which were considered to be within the range of efficacy in literature. Conclusion: This clinical study is the first GCP PET in Japan and the synthesis of [18F]FK960 succeeded under GMP regulation. In this study, PET can detect the distribution of the new drug candidate in the living body and calculate the brain concentration. The pharmacokinetic study using PET is useful for estimating the clinical dose of the drug candidate and will be a powerful tool for new drug research and development.
    International Congress Series 01/2004; 1264:40-43.
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    ABSTRACT: A dual-isotope simultaneous acquisition (DISA) single-photon emission tomography (SPET) protocol with fluorine-18 fluorodeoxyglucose ((18)F-FDG) and a technetium-99m labelled flow tracer is attractive because it permits assessment of both myocardial glucose utilisation and flow within a single study. Differences in physical and physiological characteristics between (18)F-FDG and the (99m)Tc-labelled flow tracer, however, may cause differences in myocardial activity distribution between the agents. The aim of this study was to investigate the relation between the myocardial distribution of (18)F-FDG and a (99m)Tc-labelled flow tracer on DISA SPET in comparison with nitrogen-13 ammonia/(18)F-FDG positron emission tomography (PET). Nine normal volunteers without cardiac disease and ten patients with known coronary artery disease (CAD) underwent (13)N-ammonia/(18)F-FDG PET and (99m)Tc-sestamibi/(18)F-FDG DISA SPET. Using a semiquantitative polar map approach, the left ventricular myocardium was divided into nine segments, and relative regional activity was calculated for each segment. A segment was considered to have concordant uptake between (18)F-FDG and flow tracer if the difference in measured regional activity between the tracers was < or =10% of peak activity, and the percentage of concordant segments was calculated for each subject. There was a good overall concordance of myocardial activity between the agents on DISA SPET (84.0%+/-14.8%) in normals, which was comparable to that seen on PET (86.4%+/-14.5%, NS vs DISA SPET). However, the myocardial activity distributions of (18)F-FDG and flow tracer were not identical in that reduced flow tracer activity was seen in the basal segments on DISA SPET in both normals and CAD patients. It is concluded that there is good overall concordance of activity between (18)F-FDG and flow tracer in normal myocardium on DISA SPET, which is comparable to that on PET, supporting the use of combined (99m)Tc-flow tracer/(18)F-FDG imaging for the detection of viable myocardium. However, there is a difference in the myocardial activity distribution between the agents in both normals and CAD patients, the difference being particularly evident in the basal segments. Therefore, careful image interpretation that takes into consideration the different normal activity distribution between the tracers and/or a tracer-specific normal database is necessary for comparison with patient studies.
    European journal of nuclear medicine and molecular imaging 10/2002; 29(10):1357-64. · 5.11 Impact Factor
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    ABSTRACT: SPECT with (18)F-FDG has emerged as an alternative to dedicated PET for the assessment of myocardial viability. However, whether FDG SPECT can reliably quantify the extent of viable and scarred myocardium is uncertain. The aim of this study was to investigate whether SPECT with an (18)F-labeled agent would provide information on defect size similar to that provided by dedicated PET. Imaging was performed using an elliptic cylinder chest phantom with simulated bone, lung, mediastinum, liver, and heart. (18)F was administered into the myocardium, mediastinum, right and left ventricular cavities, and liver. Plastic inserts (n = 11) ranging in size from 2% to 60% of the myocardium were used to simulate transmural myocardial infarctions. The chest phantom was imaged with a dedicated PET camera and with a double-head SPECT camera equipped with ultra-high-energy collimators. Both SPECT and PET data were analyzed using a semiquantitative polar map approach. Defects were quantified using various cutoff thresholds ranging from 30% to 80% of peak activity and were expressed as a percentage of the left ventricular myocardium. Defect size as measured by SPECT or PET was compared with true defect size. The measured SPECT defect size was highly variable depending on the cutoff used, whereas PET defect size was relatively constant over the range of cutoffs tested. The mean absolute difference between measured and true defect sizes was minimal at a cutoff of 50% of peak activity for both SPECT (3.3% +/- 3.3%) and PET (2.7% +/- 2.5%). For this threshold, both SPECT and PET measurements showed an excellent correlation with true defect size (r = 0.98 for SPECT and 0.99 for PET). The correlation between SPECT and PET measurements was also excellent (r = 0.99; P < 0.01). If an appropriate threshold is used to define a defect, SPECT with an (18)F-labeled agent can accurately measure defect size similarly to the manner of PET.
    Journal of Nuclear Medicine 11/2001; 42(10):1579-85. · 5.77 Impact Factor
  • Journal of Nuclear Cardiology 01/2001; 8(1). · 2.85 Impact Factor
  • Journal of Nuclear Cardiology 01/2001; 8(1). · 2.85 Impact Factor
  • Journal of Nuclear Cardiology 01/2001; 8(1). · 2.85 Impact Factor
  • M Matsudaira, K Nakajima, N Tonami, K Hisada
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    ABSTRACT: We devised "four-energy-window" (FEW) method which permits simultaneous acquisition for dual isotope single photon emission tomography (SPECT) studies using 99mTc and 123I of which photopeak is in close vicinity to each other. This acquisition method requires a total of four energy windows: two main windows for 99mTc (126-143 keV) and 123I (156-175 keV), respectively, and two 5% sub-windows which are set below the 99mTc window and above the 123I window, respectively. Two virtual windows (5%) are additionally set above the 99mTc and below the 123I window, respectively, to apply the triple-energy-window (TEW) method for the scatter correction. A phantom study demonstrated that photocounts from the two radionuclides could be completely separated from each other and that SPECT images obtained had preferable property for quantitative analysis. This method was applied to clinical, dual-radionuclide myocardial studies using 99mTc-MIBI and 123I-BMIPP, and was found to provide excellent images each tracer.
    Kaku igaku. The Japanese journal of nuclear medicine 12/1997; 34(11):1013-20.
  • M Matsudaira, K Nakajima
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    ABSTRACT: It is important for obtaining a left ventricular volume curve and ejection fraction from a multigated blood pool image (MGBP image) to accurately subtract the background (BG) from the image. We devised a new method of accurately subtracting the BG with good reproducibility. This method (tentatively called the ICS method) is as follows. An image, on which n times (n = 0, 1, 2, 3,..., N-1) an adequately low constant (k) is subtracted from the MGBP image at every pixel of the image matrix, is prepared. When n equals 0, constant is not subtracted from the image, therefore it is original MGBP image. Then the original (n = 0) and constant (nk: n = 1, 2, 3,..., N-1) subtraction MGBP images were prepared. The constant was defined as about 5% of the maximum pixel count in the end-diastole of the left ventricle. Rough region of interest (ROI) were set at the left ventricle on these MGBP images, and time activity curves (TACs, left ventricular volume curves) on each image were prepared. These N kinds of curves are shifted in parallel for normalization in the first frame (end-diastole). The first frame count on the original MGBP image is normalized. As a result, TACs obtained by inadequate subtraction in which subtraction of the constant does not reach the BG count, overlap completely, while TACs obtained by subtraction over the BG gradually separate from the overlapping curves. The MGBP image including a curve located in the border between the overlapping curve and the separated curve is regarded as the image accurately subtracting the BG, and the constant of subtraction (nk) as the BG count for each pixel. The border is obtained by analyzing changes in count of the end-systolic frame of each TAC normalized. The ICS method provides computer software that is performed automatically within a short time by setting a rough ROI at the left ventricle on the end-diastolic MGBP image.
    Kaku igaku. The Japanese journal of nuclear medicine 11/1996; 33(10):1053-63.
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    ABSTRACT: Triple-energy window (TEW) method is a simple and practical approach for correcting Compton scatter in single-photon emission tracer studies. The fraction of scatter correction, with a point source or 30 ml-syringe placed under the camera, was measured by the TEW method. The scatter fraction was 55% for 201Tl, 29% for 99mTc, 57% for 123I. Composite energy spectra were generated and separated by the TEW method. Combination of 99mTc and 201Tl was separated well, and 201Tl and 123I were separated within an error of 10%; whereas asymmetric photopeak energy window was necessary for separating 123I and 99mTc. By applying this method to myocardial SPECT study, the effect of scatter elimination was investigated in each myocardial wall by polar may and profile curve analysis. The effect of scatter was higher in the septum and the inferior wall. The count ratio relative to the anterior wall including scatter was 9% higher in 123I, 7-8% higher in 99mTc and 6% higher in 201Tl. Apparent count loss after scatter correction was 30% for 123I, 13% for 99mTc and 38% for 201Tl. Image contrast, as defined myocardium-to-left ventricular cavity count ratio, improved by scatter correction. Since the influence of Compton scatter was significant in cardiac planar and SPECT studies; the degree of scatter fraction should be kept in mind both in quantification and visual interpretation.
    Kaku igaku. The Japanese journal of nuclear medicine 09/1995; 32(9):959-67.
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    ABSTRACT: High-resolution three-headed single photon emission computed tomography (SPET) equipped with fan-beam collimators was applied to myocardial perfusion imaging in infants aged from 1 to 11 months (n = 5). A tabletop designed specifically for infants was fixed on the SPET couch to reduce the radius of camera rotation to 13.2 cm. Significant improvement in resolution was achieved with the fan-beam collimators compared to parallel-hole high-resolution collimators. With the administration of approximately 37 MBq (26-44 MBq) 201Tl, 5 min acquisition time was possible for SPET imaging, which provided good image quality in all patients. Thus, a smaller administration dose is possible within a practical short acquisition time. High-resolution fan-beam SPET imaging can be a routine diagnostic method for heart disease in newborn babies and infants.
    Nuclear Medicine Communications 09/1992; 13(8):604-8. · 1.38 Impact Factor
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    ABSTRACT: A method for SPECT data acquisition, "continuous repetitive rotation acquisition," was developed with a high-sensitivity three-headed SPECT system. The method was applied to the dynamic imaging of 99mTc-SQ30217, a new myocardial imaging agent. After acquisition and reconstruction of SPECT data every minute, projection images at arbitrary intervals were used for tomographic reconstruction to determine the best timing of SPECT imaging in 99mTc-SQ30217. Based on a comparison of several possible acquisition intervals, SPECT data acquisition within 9 min after injection is recommended because of high myocardial uptake (myocardium-to-lung ratio, 2.83 +/- 0.42 (mean +/- s.e.m.) at 3-6 min) and relatively low hepatic uptake (myocardium-to-liver ratio, 0.85 +/- 0.13 at 3-6 min). The rate constant of the clearance of 99mTc-SQ30217 from the myocardium obtained by SPECT was: k1 = 0.249 +/- 0.050 per min (average half-life = 2.8 min) and k2 = 0.012 +/- 0.004/min (average half-life = 58 min). The continuous repetitive rotation acquisition SPECT study appears useful for imaging SQ30217 with its rapidly changing myocardial distribution.
    Journal of Nuclear Medicine 07/1991; 32(6):1273-7. · 5.77 Impact Factor
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    ABSTRACT: A three-headed single-photon emission computed tomography (SPECT) system was developed, and the fundamental SPECT performance and clinical applications were investigated. The full width at half maximum (FWHM) of the SPECT system is 10.8 mm at the center of rotation with a radius of 20 cm. In clinical applications, 201Tl myocardial images with the three-headed system demonstrated a distincter and thinner myocardium compared to those with the dual-headed system. The right ventricular wall was observed even in patients without right ventricular overload. Owing to both the increased sensitivity and resolution, the three-headed system has high performance capability in clinical use such as ECG-gating and dynamic studies.
    Kaku igaku. The Japanese journal of nuclear medicine 06/1990; 27(5):493-7.
  • Kaku igaku. The Japanese journal of nuclear medicine 10/1986; 23(10):1423-34.
  • Kaku igaku. The Japanese journal of nuclear medicine 01/1986; 22(12):1781-7.
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    01/1986;