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Diagnostic Performance of Artificial Neural Network for Detecting Ischemia in Myocardial Perfusion Imagingmore
by Kenichi Nakajima and Koichi Okuda
The purpose of this study was to apply an artificial neural network (ANN) in patients with coronary artery disease (CAD) and to characterize its diagnostic ability compared with conventional visual and quantitative methods in myocardial... more
The purpose of this study was to apply an artificial neural network (ANN) in patients with coronary artery disease (CAD) and to characterize its diagnostic ability compared with conventional visual and quantitative methods in myocardial perfusion imaging (MPI).Methods and Results:A total of 106 patients with CAD were studied with MPI, including multiple vessel disease (49%), history of myocardial infarction (27%) and coronary intervention (30%). The ANN detected abnormal areas with a probability of stress defect and ischemia. The consensus diagnosis based on expert interpretation and coronary stenosis was used as the gold standard. The left ventricular ANN value was higher in the stress-defect group than in the no-defect group (0.92±0.11 vs. 0.25±0.32, P<0.0001) and higher in the ischemia group than in the no-ischemia group (0.70±0.40 vs. 0.004±0.032, P<0.0001). Receiver-operating characteristics curve analysis showed comparable diagnostic accuracy between ANN and the scoring ...
Publication Date: Jan 3, 2015
Publication Name: Circulation journal : official journal of the Japanese Circulation Society
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The importance of population-specific normal database for quantification of myocardial ischemia: comparison between Japanese 360 and 180-degree databases and a US databasemore
by Kenichi Nakajima and Koichi Okuda
Publication Date: 2009
Publication Name: Journal of Nuclear Cardiology
Research Interests: Nuclear medicine, Japan, Humans, United States, Female, and 11 moreMale, Middle Aged, Single Photon Emission Computed Tomography, Nuclear Cardiology, Reproducibility of Results, Myocardial Perfusion Imaging, Coronary Artery Disease, Sensitivity and Specificity, Reference Values, Area Under the Curve, and Quantitative Evaluation
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Semi-automated algorithm for calculating heart-to-mediastinum ratio in cardiac Iodine-123 MIBG imagingmore
by Kenichi Nakajima and Koichi Okuda
Publication Date: 2011
Publication Name: Journal of Nuclear Cardiology
Research Interests: Algorithms, Positron Emission Tomography, Humans, Female, Male, and 11 moreMiddle Aged, Image Enhancement, Observer Variation, Nuclear Cardiology, Myocardium, Reproducibility of Results, Correlation coefficient, Radiopharmaceuticals, Sensitivity and Specificity, Region of Interest, and Heart Diseases
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Publication Date: 2007
Publication Name: Journal of Nuclear Cardiology
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by Koichi Okuda and Kenichi Nakajima
Publication Date: 2013
Publication Name: European Journal of Nuclear Medicine and Molecular Imaging
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Attenuation correction of myocardial SPECT by scatter-photopeak window method in normal subjectsmore
by Koichi Okuda and Kenichi Nakajima
Publication Date: 2009
Publication Name: Annals of Nuclear Medicine
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Characterization of Japanese standards for myocardial sympathetic and metabolic imaging in comparison with perfusion imagingmore
by Kenichi Nakajima and Koichi Okuda
Publication Date: 2009
Publication Name: Annals of Nuclear Medicine
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Publication Date: 2010
Publication Name: Annals of Nuclear Medicine
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The aim of this study was to characterize the optimal reconstruction parameters for ordered-subset expectation maximization (OSEM) with attenuation correction, scatter correction, and depth-dependent resolution recovery (OSEMACSCRR). We... more
The aim of this study was to characterize the optimal reconstruction parameters for ordered-subset expectation maximization (OSEM) with attenuation correction, scatter correction, and depth-dependent resolution recovery (OSEMACSCRR). We assessed the optimal parameters for OSEMACSCRR in an anthropomorphic torso phantom study, and evaluated the validity of the reconstruction parameters in the groups of normal volunteers and patients with abnormal perfusion. Images of the anthropomorphic torso phantom, 9 normal volunteers and 7 patients undergoing myocardial perfusion SPECT were acquired with a SPECT/CT scanner. SPECT data comprised a 64×64 matrix with an acquisition pixel size of 6.6 mm. A normalized mean square error (NMSE) of the phantom image was calculated to determine both optimal OSEM update and a full width at half maximum (FWHM) of Gaussian filter. We validated the myocardial count, contrast and noise characteristic for clinical subjects derived from OSEMACSCRR processing. OSEM with depth-dependent resolution recovery (OSEMRR) and filtered back projection (FBP) were simultaneously performed to compare OSEMACSCRR. The combination of OSEMACSCRR with 90-120 OSEM updates and Gaussian filter with 13.2-14.85 mm FWHM yielded low NMSE value in the phantom study. When we used OSEMACSCRR with 120 updates and Gaussian filter with 13.2 mm FWHM in the normal volunteers, myocardial contrast showed significantly higher value than that derived from 120 updates and 14.85 mm FWHM. OSEMACSCRR with the combination of 90-120 OSEM updates and 14.85 mm FWHM produced lowest % root mean square (RMS) noise. Regarding the defect contrast of patients with abnormal perfusion, OSEMACSCRR with the combination of 90-120 OSEM updates and 13.2 mm FWHM produced significantly higher value than that derived from 90-120 OSEM updates and 14.85 mm FWHM. OSEMACSCRR was superior to FBP for the % RMS noise (8.52±1.08 vs. 9.55±1.71, p=0.02) and defect contrast (0.368±0.061 vs. 0.327±0.052, p=0.01), respectively. Clinically optimized the number of OSEM updates and FWHM of Gaussian filter were (1) 120 updates and 13.2 mm, and (2) 90-120 updates and 14.85 mm on the OSEMACSCRR processing, respectively. Further assessment may be required to determine the optimal iterative reconstruction parameters in a larger patient population.
Publication Date: 2014
Publication Name: Annals of Nuclear Medicine
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Background: To overcome differences in a collimator choice for a 123 I-MIBG heart to mediastinum (H/M) ratio, we examined multi-window correction methods with 123 I-dual-window (IDW) and triple-energy-window (TEW) acquisition. Methods and... more
Background: To overcome differences in a collimator choice for a 123 I-MIBG heart to mediastinum (H/M) ratio, we examined multi-window correction methods with 123 I-dual-window (IDW) and triple-energy-window (TEW) acquisition. Methods and Results: Standard phantoms which consisted of heart, mediastinum, lung and liver, were generated. Three correction methods were compared: TEW and two IDW methods (IDW 0 and IDW 1 ). Low-energy high-resolution (LEHR), medium-energy (ME) and 123 I specific low-medium-energy high-resolution (LMEHR) collimators were used. Clinical studies were performed in 10 patients. In the phantom study, the H/M ratio was significantly underestimated without correction both with the LEHR and ME collimators (70% and 88% of the true value). When H/M with the LEHR collimator was divided by uncorrected H/M with the ME collimator, the ratio was 80%+/-4%, 98%+/-5%, 104%+/-7%, 98%+/-5% for no correction, TEW, IDW 0 and IDW 1 methods, respectively. Clinical studies with the...