Papers by Kenichi Nakajima
Annals of nuclear medicine, Mar 13, 2024
Objective This study aimed to determine the prognostic value of the flare phenomenon in patients ... more Objective This study aimed to determine the prognostic value of the flare phenomenon in patients with metastatic castrationresistant prostate cancer (mCRPC) using the bone scan index (BSI) derived from 99m Tc-methylenediphosphonate (MDP) bone scintigraphy images. Methods We categorized 72 patients from the PROSTAT-BSI registry with mCRPC who were followed-up for 2 years after starting docetaxel chemotherapy to groups based on pre-chemotherapy BSI values of < 1, 1-4, and > 4. We assessed the effects of the flare phenomenon (defined as a > 10% increase in the BSI within 3 months of starting chemotherapy, followed by > 10% improvement within the next 3 months) on survival using Kaplan-Meier curves and Cox proportional hazard analyses. Results The flare phenomenon was found in 26 (36%) of the 72 patients. Prostate-specific antigen (PSA), alkaline phosphatase (ALP), and hemoglobin (Hb) levels steadily increased, then deteriorated in patients with and without flare, respectively. Elevated BSI and PSA values at 3 months after starting therapy and the absence of abiraterone or/and enzalutamide therapy led to poor 2-year overall survival (OS) in the group without flare. In contrast, no influence was noticeable in the group with flare. The results of multivariable analyses that included only factors associated with PSA and BSI showed that increased baseline BSI (hazard ratio [HR], 1.39; 95% confidence interval [CI], 1.04-1.86; P = 0.023) and PSA (HR, 7.15; 95% CI 2.13-24.04; P = 0.0015) values could be independent risk factors for patients with mCRPC without flare. However, these factors lost significance during flare. The risk for all-cause death was significantly higher among patients with BSI > 4 without, than with flare. The results of univariable analyses indicated that flare positively impacted survival (HR, 0.24; 95% CI 0.06-0.91; P = 0.035). Multivariable analysis did not identify any factors that could predict outcomes. Conclusion Favorable prognosis, with fewer disturbances from other factors such as the use of abiraterone or/and enzalutamide, PSA changes, and BSI, was attainable in cases when the mCRPC patient demonstrated flare phenomenon. Follow-up bone scintigraphy at least every 3 months could help to determine the prognosis of patients with bone metastasis of mCRPC.
Journal of Nuclear Cardiology
Background Absolute quantitative myocardial perfusion SPECT requires addressing of aleatory and e... more Background Absolute quantitative myocardial perfusion SPECT requires addressing of aleatory and epistemic uncertainties in conjunction with providing image quality sufficient for lesion detection and characterization. Iterative reconstruction methods enable the mitigation of the root causes of image degradation. This study aimed to determine the feasibility of a new SPECT/CT method with integrated corrections attempting to enable absolute quantitative cardiac imaging (xSPECT Cardiac; xSC). Methods We compared images of prototype xSC and conventional SPECT (Flash3DTM) acquired at rest from 56 patients aged 71 ± 12 y with suspected coronary heart disease. The xSC prototype comprised list-mode acquisitions with continuous rotation and subsequent iterative reconstructions with retrospective electrocardiography (ECG) gating. Besides accurate image formation modeling, patient-specific CT-based attenuation and energy window-based scatter correction, additionally we applied mitigation for p...
Annals of Nuclear Medicine
The purpose of this practice recommendation is to specifically identify the critical steps involv... more The purpose of this practice recommendation is to specifically identify the critical steps involved in performing and interpreting 123 I-β-methyl-iodophenyl-pentadecanoic acid (BMIPP) single-photon emission computed tomography (SPECT) and measurement of washout rate (WR) from the heart. This document will cover backgrounds, patient preparation, testing procedure, visual image interpretation, quantitation methods using planar and SPECT studies, and reporting of WR. The pitfall and some tips for the calculation of 123 I-BMIPP WR are also included. The targets of global and regional WR calculation include ischemic heart disease, cardiomyopathy, heart failure, and triglyceride deposit cardiomyovasculopathy, an emerging rare heart disease.
Journal of Nuclear Cardiology
Kaku igaku. The Japanese journal of nuclear medicine
Kaku igaku. The Japanese journal of nuclear medicine, 1981
Rinsho hoshasen. Clinical radiography, 1982
Kaku igaku. The Japanese journal of nuclear medicine, 1980
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 1984
A new method for evaluating segmental wall motion by length-based Fourier analysis is described. ... more A new method for evaluating segmental wall motion by length-based Fourier analysis is described. Fourier analysis is performed on a series of lengths from a center to edges of the ventricle, generating parameters of percent length shortening (%LS) and phase of the segment (length-based phase). The reproducibility of the result was good, since the algorithm was automatic except for the setting of the ventricular region as a mask image to exclude surrounding blood pools. This program can be applied for quantification of ventricular wall-motion abnormalities in gated blood-pool studies, and for analysis of the timing of ventricular contraction in gated blood-pool emission computed tomography to detect the site of an accessory conduction pathway in patients with Wolff-Parkinson-White syndrome.
Annals of Nuclear Medicine
While coronary heart disease remains a global cause of mortality, the prevalence of heart failure... more While coronary heart disease remains a global cause of mortality, the prevalence of heart failure (HF) is increasing in developed countries including Japan. The continuously increasing aging population and the relatively low incidence of ischemic origins are features of the HF background in Japan. Information about nuclear cardiology practice and prognosis has accumulated, thanks to the multicenter prognostic J-ACCESS investigations (Series 1‒4) over two decades in Japan. Although the rate of hard cardiac events is lower in Japan than in the USA and Europe, similar predictors have been identified as causes of major adverse cardiac events. The highest proportion (50–75%) of major events among patients indicated for nuclear cardiology examinations in the J-ACCESS registries is severe HF requiring hospitalization. Therefore, the background and the possible reasons for the higher proportion of severe HF events in Japan require clarification. Combinations of age, myocardial perfusion def...
Annals of Nuclear Medicine
Objective This study aimed to optimize various methods of calculating washout rates (WRs) of 123I... more Objective This study aimed to optimize various methods of calculating washout rates (WRs) of 123I-β-methyl-p-iodophenyl-pentadecanoic (BMIPP), as they are essential to diagnose triglyceride deposit cardiomyovasculopathy (TGCV) which is a rare disease entity identified in Japan and has been encoded in Orphanet (ORPHA code 565612). Methods We calculated WRs of 123I-BMIPP from early (20 min) and delayed (200 min) images. We evaluated six methods of calculating WRs to discriminate TGVC patients (age, 56.8 ± 14.6 y; male, n = 13; female, n = 4) and 21 123I-BMIPP studies were involved including 4 follow-up studies. Washout rates were calculated by two planar methods using anterior images with cardiac and background regions of interest (ROIs) and by four SPECT methods using either array and polar plots or summed short-axis images. The final diagnoses of TGCV were confirmed according to the 2020 diagnostic criteria, and the diagnostic accuracy of WRs calculated using the six methods was ana...
Journal of Nuclear Cardiology
Annals of Nuclear Cardiology
Machine learning has become popular in clinical practice, and the amount of research that uses ar... more Machine learning has become popular in clinical practice, and the amount of research that uses artificial intelligence is rapidly increasing. In contrast to conventional statistical and rule-based methods, machine learning creates algorithms based only on combinations of input and output databases. Basic understanding of the internal workings of artificial intelligence, its structures and need for appropriate databases, as well as its strengths and weaknesses is important for efficient machine learning application. The cardiological applications of machine learning include diagnosing coronary artery diseases and heart failure, and examples are addressed herein. A preliminary application of machine learning to a 123 I-metaiodobenzylguanidine-based risk model appears promising, and further studies using similar approaches are anticipated. Nuclear medicine physicians and cardiologists should play key roles in developing machine learning-based methods to ensure practical and reliable decisions.
Annals of Nuclear Medicine
Objectives 123I-ioflupane has been clinically applied to dopamine transporter imaging and visual ... more Objectives 123I-ioflupane has been clinically applied to dopamine transporter imaging and visual interpretation assisted by region-of-interest (ROI)-based parameters. We aimed to build a multivariable model incorporating machine learning (ML) that could accurately differentiate abnormal profiles on 123I-ioflupane images and diagnose Parkinson syndrome or disease and dementia with Lewy bodies (PS/PD/DLB). Methods We assessed 123I-ioflupane images from 239 patients with suspected neurodegenerative diseases or dementia and classified them as having PS/PD/DLB or non-PS/PD/DLB. The image features of high or low uptake (F1), symmetry or asymmetry (F2), and comma- or dot-like patterns of caudate and putamen uptake (F3) were analyzed on 137 images from one hospital for training. Direct judgement of normal or abnormal profiles (F4) was also examined. Machine learning methods included logistic regression (LR), k-nearest neighbors (kNNs), and gradient boosted trees (GBTs) that were assessed us...
Annals of Nuclear Medicine
Purpose Selecting patients with coronary multivessel disease (MVD) or no stenosis using myocardia... more Purpose Selecting patients with coronary multivessel disease (MVD) or no stenosis using myocardial perfusion imaging (MPI) is challenging. We aimed to create a model to predict MVD using a combination of quantitative MPI values and background factors of patients. We also assessed whether patients in the same database could be selected who do not require rest studies (stress-only imaging). Methods We analyzed data from 1001 patients who had been assessed by stress MPI at 12 centers and 463 patients who had not undergone revascularization in Japan. Quantitative values based on MPI were obtained using cardioREPO software, which included myocardial perfusion defect scores, left ventricular ejection fractions and volumes. Factors in MPI and clinical backgrounds that could predict MVD were investigated using univariate and multivariate analyses. We also investigated whether stress data alone could predict patients without coronary stenosis to identify candidates for stress-only imaging. R...
Scientific Reports, 2020
The 123I-labeled meta-iodobenzylguanidine (MIBG) is an analogue of noradrenaline that can evaluat... more The 123I-labeled meta-iodobenzylguanidine (MIBG) is an analogue of noradrenaline that can evaluate cardiac sympathetic activity in scintigraphy. Quantitative analysis of 123I-MIBG images has been verified in patients with heart failure and neurodegenerative diseases. However, quantitative results differ due to variations in scintigraphic imaging procedures. Here, we created and assessed the clinical feasibility of a calibration method for 123I-MIBG imaging. The characteristics of scintigraphic imaging systems were determined using an acrylic calibration phantom to generate a multicenter phantom imaging database. Calibration factors corresponding to the scintigraphic imaging procedures were calculated from the database and applied to a clinical study. The results of this study showed that the calibrated analysis eliminated inter-institutional differences among normal individuals. In summary, our standardization methodology for 123I-MIBG scintigraphy could provide the basis for improv...
Journal of Nuclear Cardiology, 2019
See related article, pp. 1692-1701 A weather forecast of rain tomorrow is a dichotomic prediction... more See related article, pp. 1692-1701 A weather forecast of rain tomorrow is a dichotomic prediction, whereas a forecast that predicts a chance of rain is probabilistic as opposed to a prediction of either sunshine or rain is deterministic. When the probability of rain is 40%, precautions could include bringing an umbrella, or wearing a raincoat before going out, or both, or neither. The final choice of a subsequent action depends on having appropriate information. Although an approach based on probability is essentially included in the process of any medical decision, specific thresholds of normal and abnormal values are often applied. For example, anemia can be defined when hemoglobin values are \ 12 and 13 g/dL in women and in men, respectively (though these values might differ slightly among laboratories). Heart-to-mediastinum (H/M) ratios of 1.6, 1.68, and 1.75 in 123 I-metaiodobenzylguanidine (mIBG) images might signal a poor prognosis for patients with heart failure. 1-3 Such thresholds are straightforward and help to guide subsequent actions in clinical practice; however, the question remains as to how appropriate thresholds are determined. In this issue of the Journal of Nuclear Cardiology, Roberts and colleagues described using 123 I-mIBG to discriminate dementia with Lewy bodies (DLB) and Alzheimer disease (AD) and compared their findings Volume 28, Number 4;1702-6 Diagnostic threshold and probability
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Papers by Kenichi Nakajima