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Objective To improve image quality for low-count bone scintigraphy whole-body images using deep learning and evaluate their applicability in clinical practice.Methods Five hundred fifty patients were included in the study. Low-count Original images (75%, 50%, 25%, 10%, and 5% counts) were generated from Reference images (100% counts) using Poisson resampling. Patients were randomly divided into training (500) and evaluation (50) groups. Output (DL-filtered) images were obtained after training with U-Net using Reference images as teacher data. Gaussian-filtered images were generated for comparison. Peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) to the Reference image were calculated to determine image quality. Artificial neural network (ANN) value, bone scan index (BSI), and number of hotspots (Hs) were computed using BONENAVI analysis for patients with and without bone metastases, to assess diagnostic performance. Accuracy of bone metastasis detection and area under the curve (AUC) were calculated. Original, Gaussian-filtered, and DL-filtered images were compared with Reference images.Results PSNR and SSIM for DL-filtered images were highest in all count percentages. BONENAVI analysis values for DL-filtered images did not differ significantly regardless of the presence or absence of bone metastases. BONENAVI analysis values for Original and Gaussian-filtered images differed significantly at Conclusions Our deep learning model improved image quality and bone metastasis detection accuracy for low-count bone scintigraphy whole-body images, suggesting its applicability in clinical practice.

A 14-year-old boy presented to the hospital with pain in the right lower abdomen. His condition was diagnosed as acute appendicitis. An emergency operation was performed, and histopathological examination revealed an actinomycete-related organism in the excised appendicitis specimen. On 16S rRNA gene sequence analysis, "Candidatus Actinobaculum timonae" was identified, which is the first known case in a pediatric patient.

PURPOSE Computed tomography (CT)-based attenuation correction (CTAC) in single-photon emission computed tomography (SPECT) is highly accurate, but it requires hybrid SPECT/CT instruments and additional radiation exposure. To obtain attenuation correction (AC) without the need for additional CT images, a deep learning method was used to generate pseudo-CT images has previously been reported, but it is limited because of cross-modality transformation, resulting in misalignment and modality-specific artifacts. This study aimed to develop a deep learning-based approach using non-attenuation-corrected (NAC) images and CTAC-based images for training to yield AC images in brain-perfusion SPECT. This study also investigated whether the proposed approach is superior to conventional Chang's AC (ChangAC). METHODS In total, 236 patients who underwent brain-perfusion SPECT were randomly divided into two groups: the training group (189 patients; 80%) and the test group (47 patients; 20%). Two models were constructed using Autoencoder (AutoencoderAC) and U-Net (U-NetAC), respectively. ChangAC, AutoencoderAC, and U-NetAC approaches were compared with CTAC using qualitative analysis (visual evaluation) and quantitative analysis (normalized mean squared error [NMSE] and the percentage error in each brain region). Statistical analyses were performed using the Wilcoxon signed-rank sum test and Bland-Altman analysis. RESULTS U-NetAC had the highest visual evaluation score. The NMSE results for the U-NetAC were the lowest, followed by AutoencoderAC and ChangAC (P

The most recent statement published by the International Commission on Radiological Protection describes a reduction in the maximum allowable occupational eye lens dose from 150 to 20 mSv/year (averaged over 5-year periods). Exposing the eye lens to radiation is a concern for nuclear medicine staff who handle radionuclide tracers with various levels of photon energy. This study aimed to define the optimal dosimeter and means of measuring the amount of exposure to which the eye lens is exposed during a routine nuclear medicine practice. A RANDO human phantom attached to Glass Badge and Luminess Badge for body or neck, DOSIRIS and VISION for eyes, and nanoDot for body, neck, and eyes was exposed to

Targeted radioisotope therapy (TRT) is a radiotherapy using radioisotope or drug incorporating it and has been used as a treatment for selectively irradiating cancer cells. In recent years, interest in TRT has increased due to improvements in radionuclide production technology, development of new drugs and imaging modalities, and improvements in radiation technology. In order to enhance the effect of TRT, measurement of individual radiation doses to tumor tissue and organs at risk is important using highly quantitative nuclear medicine images. In this paper, we present a review of literature on optimization of TRT, which is a new research area from the perspective of radiation technology.

Background: Triglyceride (TG) deposit cardiomyovasculopathy (TGCV) is a novel cardiovascular disorder and was recently encoded as an orphan disease in Europe (ORPHA code: 565612). Defective lipolysis results in TG accumulation in the myocardium and coronary arteries in TGCV. The myocardial washout rate (WR) of iodine-123-β-methyl iodophenyl-pentadecanoic acid (BMIPP) is an essential indicator to evaluate myocardial lipolysis in vivo. TGCV is classified into primary and idiopathic type with and without PNPLA2 mutation, respectively. Here, we present the clinical correlation perspectives of TGCV patients in Chiba, Japan, to increase the awareness of this orphan disease and facilitate its diagnosis. Methods: We enrolled 234 patients who underwent BMIPP scintigraphy between September 2015 and July 2019. The diagnosis of TGCV was made based on the criteria we reported previously. Blood smear tests were performed for TGCV classification. The distributions of TGCV in each comorbidity were investigated. Results: In total, 104 patients were diagnosed with definitive idiopathic TGCV (I-TGCV). They had various comorbid conditions, including heart failure with reduced ejection fraction and multivessel coronary artery disease requiring revascularization. Moreover, the serum TG levels in I-TGCV patients were not high, and there was no correlation between serum TG level and BMIPP WR (n=205, p-value=0.31), supporting the pathophysiological hypothesis of TGCV. Conclusion: I-TGCV patients showed multiple coexistence of coronary artery disease, heart failure of unknown etiology, or diabetes mellitus. For patients with such clinical characteristics, BMIPP scintigraphy and calculation of WR should be considered proactively for the diagnosis of TGCV.

Cerebral blood flow (CBF) and dopamine transporter (DAT) images are clinically used for the differential diagnosis of parkinsonian disorders.This study aimed to examine the correlation of CBF with striatal DAT in patients with Parkinson's disease (PD) and atypical parkinsonian syndromes (APS) and evaluate the diagnostic power of DAT-correlated CBF in PD through machine learning with each imaging modality alone or in combination.Fifty-eight patients with PD and 71 with APS (24 with multiple system atrophy, 21 with progressive supranuclear palsy, and 26 with corticobasal syndrome) underwentThe PD group showed more affected striatal DAT binding positively correlated with the ipsilateral prefrontal perfusion and negatively with the bilateral cerebellar perfusion. In corticobasal syndrome, striatal DAT binding positively correlated with the ipsilateral prefrontal perfusion and negatively with the contralateral precentral perfusion. In Richardson's syndrome, striatal DAT binding positively correlated with perfusion in the ipsilateral precentral cortex and basal ganglia. Machine learning showed that the combination of CBF and DAT was better for delineating PD from APS (area under the curve [AUC] = 0.87) than either CBF (0.67) or DAT (0.50) alone.In PD and four-repeat tauopathy, prefrontal perfusion was related to ipsilateral nigrostriatal dopaminergic function. This dual-tracer frontostriatal relationship may be effectively used as a diagnostic tool for delineating PD from APS. © 2022 International Parkinson and Movement Disorder Society.

Repetitive transcranial magnetic stimulation (rTMS) is an effective clinical intervention for various neuropsychiatric diseases. However, it is still unclear whether rTMS has an effect on cognitive functioning. In this review, we aimed to systematically evaluate the cognitive effects of rTMS in depression, schizophrenia, and Alzheimer's disease. We searched PubMed (1996–2018) under the set terms to review randomized controlled trials (RCT) to examine the effectiveness of rTMS administered to the dorsolateral prefrontal cortex (DLPFC) and evaluated cognitive functions in patients with depression, schizophrenia, and Alzheimer's disease. Two authors reviewed each article and came to consensus on the inclusion and exclusion criteria. All eligible studies were reviewed, duplicates were removed, and data were extracted individually. The search identified 579 articles, 31 of which met inclusion and exclusion criteria. Among them, 15 were conducted in patients with depression, 11 in patients with schizophrenia, and 5 in patients with Alzheimer's disease. Specifically, 6 studies demonstrated a significant improvement of executive function across these diseases. Further, no evidence for cognitive adverse effects was found in these included rTMS studies. Although the heterogeneity between studies in terms of cognitive measures applied, stimulation parameters, and participants limits the ability to generalize conclusions, this review demonstrated that prefrontal rTMS could exert pro-cognitive effects on executive function and attention in some patients with depression but inconsistent cognitive impacts in any of the examined domains especially in patients with schizophrenia and Alzheimer's disease. The results warrant further rTMS studies that include systematic assessment of cognition across various neuropsychiatric diseases.

The diagnostic reference levels (DRLs) are one of several effective tools for optimizing nuclear medicine examinations and reducing patient exposure. With the advances in imaging technology and alterations of examination protocols, the DRLs must be reviewed periodically. The first DRLs in Japan were established in 2015, and since 5 years have passed, it is time to review and revise the DRLs. We conducted a survey to investigate the administered activities of radiopharmaceuticals and the radiation doses of computed tomography (CT) in hybrid CT accompanied by single photon emission computed tomography (SPECT)/CT and positron emission tomography (PET)/CT. We distributed a Web-based survey to 915 nuclear medicine facilities throughout Japan and survey responses were provided by 256 nuclear medicine facilities (response rate 28%). We asked for the facility's median actual administered activity and median radiation dose of hybrid CT when SPECT/CT or PET/CT was performed for patients with standard habitus in the standard protocol of the facility for each nuclear medicine examination. We determined the new DRLs based on the 75th percentile referring to the 2015 DRLs, drug package inserts, and updated guidelines. The 2020 DRLs are almost the same as the 2015 DRLs, but for the relatively long-lived radionuclides, the DRLs are set low due to the changes in the Japanese delivery system. There are no items set higher than the previous values. Although the DRLs determined this time are roughly equivalent to the DRLs used in the US, overall they tend to be higher than the European DRLs. The DRLs of the radiation dose of CT in hybrid CT vary widely depending on each imaging site and the purpose of the examination.

Purpose The present study aimed to define the errors in SUV and demonstrate the feasibility of SUV harmonization among contemporary PET/CT scanners using a novel National Institute of Standards and Technology (NIST)-traceable 68Ge/68Ga source as the reference standard. Methods We used 68Ge/68Ga dose calibrator and PET sources made with same batch of 68Ge/68Ga embedded in epoxy that is traceable to the NIST standard. Bias in the amount of radioactivity and the radioactive concentrations measured by the dose calibrators and PET/CT scanners, respectively, was determined at five Japanese sites. We adjusted optimal dial setting of the dose calibrators and PET reconstruction parameters to close the actual amount of radioactivity and the radioactive concentration, respectively, of the NIST-traceable 68Ge/68Ga sources to harmonize SUV. Errors in SUV before and after harmonization were then calculated at each site. Results The average bias in the amount of radioactivity and the radioactive concentrations measured by dose calibrator and PET scanner was −4.94% and −12.22%, respectively, before, and −0.14% and −4.81%, respectively, after harmonization. Corresponding averaged errors in SUV measured under clinical conditions were underestimated by 7.66%, but improved by −4.70% under optimal conditions. Conclusion Our proposed method using an NIST-traceable 68Ge/68Ga source identified bias in values obtained using dose calibrators and PET scanners, and reduced SUV variability to within 5% across different models of PET scanners at five sites. Our protocol using a standard source has considerable potential for harmonizing the SUV when contemporary PET scanners are involved in multicenter studies.

The present study aimed to define the errors in SUV and demonstrate the feasibility of SUV harmonization among contemporary PET/CT scanners using a novel National Institute of Standards and Technology (NIST)-traceableWe usedThe average bias in the amount of radioactivity and the radioactive concentrations measured by dose calibrator and PET scanner was -4.94% and -12.22%, respectively, before, and -0.14% and -4.81%, respectively, after harmonization. Corresponding averaged errors in SUV measured under clinical conditions were underestimated by 7.66%, but improved by -4.70% under optimal conditions.Our proposed method using an NIST-traceable

Background Although quantitative analysis using standardized uptake value (SUV) becomes realistic in clinical single-photon emission computed tomography/computed tomography (SPECT/CT) imaging, reconstruction parameter settings can deliver different quantitative results among different SPECT/CT systems. This study aims to propose a use of the digital reference object (DRO), which is a National Electrical Manufacturers Association (NEMA) phantom-like object developed by the Quantitative Imaging Biomarker Alliance (QIBA) fluorodeoxyglucose-positron emission tomography technical committee, for the purpose of harmonizing SUVs in Tc-99m SPECT/CT imaging. Methods The NEMA body phantom with determined Tc-99m concentration was scanned with the four state-of-the-art SPECT/CT systems. SPECT data were reconstructed using different numbers of the product of subset and iteration numbers (SI) and the width of 3D Gaussian filter (3DGF). The mean (SUVmean), maximal (SUVmax), and peak (SUVpeak) SUVs for six hot spheres (10, 13, 17, 22, 28, and 37 mm) were measured after converting SPECT count into SUV using Becquerel calibration factor. DRO smoothed by 3DGF with a FWHM of 17 mm (DRO17 mm) was generated, and the corresponding SUVs were measured. The reconstruction condition to yield the lowest root mean square error (RMSE) of SUVmeans for all the spheres between DRO17 mm and actual phantom images was determined as the harmonized condition for each SPECT/CT scanner. Then, inter-scanner variability in all quantitative metrics was measured before (i.e., according to the manufacturers’ recommendation or the policies of their own departments) and after harmonization. Results RMSE was lowest in the following reconstruction conditions: SI of 100 and 3DGF of 13 mm for Brightview XCT, SI of 160 and 3DGF of 3 pixels for Discovery NM/CT, SI of 60 and 3DGF of 2 pixels for Infinia, and SI of 140 and 3DGF of 15 mm for Symbia. In pre-harmonized conditions, coefficient of variations (COVs) among the SPECT/CT systems were greater than 10% for all quantitative metrics in three of the spheres, SUVmax and SUVmean, in one of the spheres. In contrast, all metrics except SUVmax in the 17-mm sphere yielded less than 10% of COVs after harmonization. Conclusions Our proposed method clearly reduced inter-scanner variability in SUVs. A digital phantom developed by QIBA would be useful for harmonizing SUVs in multicenter trials using SPECT/CT.

ObjectiveTo assess the cerebral blood flow (CBF) in patients with diabetic neuropathic pain, and its changes after duloxetine therapy.MethodsUsing iodine-123-N-isopropyl-p-iodoamphetamine single-photon emission computed tomography (IMP-SPECT), we performed a cross-sectional study of 44 patients with diabetes, and compared CBF in those with (n = 24) and without neuropathic pain (n = 20). In patients with neuropathic pain, we also longitudinally assessed changes in CBF 3 months after treatment with duloxetine.ResultsIMP-SPECT with voxel-based analyses showed a significant increase in cerebral blood flow in the right anterior cingulate cortex and a decrease in the left ventral striatum in patients with neuropathic pain, compared with those without pain. After duloxetine treatment, volume of interest analyses revealed a decrease in cerebral blood flow in the anterior cingulate cortex in patients with significant pain relief but not in non-responders. Furthermore, voxel-based whole brain correlation analyses demonstrated that greater baseline CBF in the anterior cingulate cortex was associated with better pain relief on the numerical rating scale.ConclusionsOur results suggest that the development of neuropathic pain is associated with increased activity in the anterior cingulate cortex, and greater baseline activation of this region may predict treatment responsiveness to pharmacological intervention.Trial registration numberUMIN000017130;Results.

Positron emission tomography (PET) is widely used for image diagnostics; making judgments for early diagnostics, differential diagnostics, staging and treatment effect. As for undertaking the large clinical trial and the multicenter study using several diagnostics, the quantitative standardization of PET images is important. We should maintain the safety and the accuracy of daily clinical images. Moreover, we have to develop a safety treatment manual for instruments, apparatus and radiopharmaceuticals in order to produce PET studies of the highest diagnostic accuracy. In addition, daily quality assurance (QA) and quality control (QC) are very important in order to achieve efficiency and safety of PET studies. The importance of the QA and the QC have been recognized from the view of clinical incident protection points. PET will become more advanced in the future, and therefore the QA and the QC for PET images will continue to important in our work. In the view-risk management, we should reaffirm the importance of both QA and QC. Furthermore, we underline the importance of the constant management system and organization in order to gain the quality enhancement of PET imaging.

Introduction: In patients with pulmonary hypertension (PH), right ventricular (RV) dysfunction as a consequence of increased RV pressure may result in RV enlargement and hypertrophy, which also increases the RV myocardial perfusion. Hypothesis: We assessed the hypothesis that RV myocardial perfusion detected by planar thallium-201 (201Tl) imaging is useful for quantitative evaluation for RV dysfunction in PH patients. Method: The study groups included 16 PH patients with chronic thromboembolic pulmonary hypertension (CTEPH) and 24 healthy controls. All subjects underwent myocardial perfusion SPECT/CT. Cardiac CT was used to obtain the optimal angle to differentiate the RV from the left ventricle (LV). Forty minutes after intravenously administration of 111 MBq of 201Tl, planar acquisition from the optimal angle was performed. In the planar image, we measured the total counts of 201Tl in the RV and LV. The relative count of the RV to LV (HR/HL) was calculated as RV myocardial perfusion indicator for this study. Mean pulmonary artery pressure (mPAP) by cardiac catheterization was obtained in all PH patients to estimate the severity. Results: HR/HL was significantly elevated in the PH group compared with control (0.57 ± 0.13 vs. 0.36 ± 0.07, p Conclusion: Relative RV accumulation in CT-guided 201Tl planar imaging by SPECT/CT was associated with the severity of PH in CTEPH patients and decreased after surgical treatment of CTEPH in parallel with the reduction of mPAP. This method may represent a novel, noninvasive monitoring tool for PH patients.

Some medical compact cyclotrons have self-shielding to reduce neutron fluxes. Thermal neutron fluxes in an 18-MeV unshielded cyclotron room and in a 16.5-MeV self-shielded cyclotron room were evaluated. In addition, the radioactivities in concrete and metals due to thermal neutrons in the cyclotron rooms for 30 years were calculated of operation such that the sum of the ratio of the nuclide concentration to the nuclide clearance level was equal to 1. The thermal neutron flux from the unshielded cyclotron was approximately 10(2) cm(-2) s(-1), whereas that from the self-shielded cyclotron was approximately 10(2) cm(-2) s(-1). The thermal neutron fluxes for concrete, stainless steel, vessel steel, and aluminum that reached their clearance levels were 9.80 × 10(4), 2.17 × 10(3), 1.87 × 10(4), and 2.41 × 10(5) cm(-2) s(-1), respectively. The specific activities in the cyclotron room were found to be sufficiently below the clearance level when the self-shield was employed.

In this study, the nuclear medicine staff wore one finger dosimeter placed at the base of the index finger of the working hand. When a physician injected radioisotope drugs, the finger dose was 22.4 microSv, that for radiological technologists handling (99m)Tc was 29.6 microSv/day (consultation period 20 days), that for a physician injecting (18)F-FDG-PET drugs was 51.3 microSv (right finger 53.9 microSv, left finger 47.2 microSv), that for pharmacists' assay of FDG was 31.5 microSv, and that for radiological technologists positioning patients was 1.9 microSv. The largest value (94.1 microSv) was observed in physicians in the case of aspiration of a delivered drug. The finger dosimeter provides an effective solution for radiation protection procedures and follow-up. All the above staff members are on rotation and do not constantly handle radioactivity throughout the year.

A medical compact cyclotron produces about 10(15) neutrons per day along with 100 GBq of (18)F. Therefore, it is important to establish radiation safety guidelines on residual radioactivity for routine operation, maintenance work, and decommissioning. Thus, we developed a simple method for measuring the thermal neutrons in a cyclotron room. In order to verify the feasibility of our proposed method, we measured the thermal neutron distribution around a cyclotron by using the activation of (23)Na in salt. We installed 78 salt dosimeters in the cyclotron room with a 50 cm mesh. The photopeak of (24)Na was measured, and the neutron flux distribution was estimated. Monitoring the neutron flux distribution in a cyclotron room appears to be useful for not only obtaining an accurate estimate of the distribution of induced radioactivity, but also optimizing the shield design for radiation safety in preparation for the decommissioning process.

High-resolution film dosimetry has been used for several decades to check and to measure two-dimensional dose distributions. However, in recent years, the automatic processor has been replaced by the spread of computed radiography, or has been little used hospitals. In this study, we measured the off-center ratio (OCR) of the open field, after an irradiating radiation beam was delivered to the imaging plate (IP) under conditions in which the IP was exposed to a fixed amount of light with fading, and compared these data with the OCR measured by an ionization-chamber dosimeter, which is the standard method used for measuring radiation dose. Profile measurement using IP could be achieved by performing light fading, even at a range of more than 100 MU. Further, by using a metallic filter, we succeeded in demonstrating that the profile measurement of IP in an open irradiation field could approximate the values of those obtained by an ionization chamber dosimeter. This method can serve as a simple, easy-to-use method for evaluating the QA of dose distribution in radiation therapy.