label: url

en: Ventilation/Perfusion Mismatch in Pulmonary Vein Stenosis Secondary to Atrial Fibrillation Ablation

en: We present two patients with a history of paroxysmal atrial fibrillation who developed pulmonary vein stenosis (PVS) following atrial fibrillation (AF) ablation. Case 1 involved a female patient in her 50s who was asymptomatic for pulmonary symptoms but was found to have a high degree of left superior PVS 15 months after AF ablation. This was demonstrated using contrast-enhanced computed tomography (CE-CT) and supported by findings of perfusion defects on ventilation-perfusion (V/Q) scan. Case 2 was a male patient in his 60s who developed progressive left superior PVS nine months after AF ablation, evidenced by serial CE-CT and V/Q scans. PVS is a rare but well-known complication of pulmonary vein ablation for the treatment of AF that can lead to severe complications if left untreated. V/Q scans effectively assess the functional significance of PVS by detecting abnormal blood flow segments. Although a V/Q mismatch characterized by reduced perfusion defects is more commonly used in evaluating pulmonary embolism, PVS should not be disregarded as a differential diagnosis. Few studies emphasize the utility of V/Q scans in managing PVS and highlight V/Q mismatch as a notable finding. This case report aimed to highlight their significance.

en: Asia Oceania Journal of Nuclear Medicine & Biology


en: Quantitative evaluation of 67Gacitrate scintigraphy in the management of nephritis

en: In Ga-citrate scintigraphy (Ga-S), visual assessment is used by evaluating renal-uptake comparison with liver and spine and is simple and objective. We adopted the standardized uptake value (SUV) for Ga-citrate and proposed two quantitative indices, active nephritis volume (ANV) and total nephritis uptake (TNU). This study clarified the utility of new Ga-S-based quantitative indices in nephritis management. Before SUV measurement, the Becquerel calibration factor of Ga-citrate was obtained using a phantom experiment. Seventy patients who underwent SPECT/CT imaging were studied. SUV, ANV, and TNU were calculated using a quantitative analysis software for bone SPECT. SUV, ANV, and TNU were analyzed using the (1) threshold method (set 40%) and constant-value method for (2) vertebral SUV, and (3) vertebral SUV. ROC analysis was used to evaluate SUV, ANV, and TNU diagnostic abilities to distinguish nephritis presence and absence as well as interstitial nephritis (IN) and non-IN. The area under the curve (AUC) for nephritis presence or absence had a good value (0.80) for SUV (1), ANV (3), and TNU (3). The AUC for differentiation between IN and non-IN groups had a good value (0.80) for SUV (1). Thus, the new Ga-S-based quantitative indices were useful to evaluate nephritis and distinguish IN and non-IN.

en: Scientific Reports

ja: Scientific Reports


en: Combined visual and quantitative assessment of somatostatin receptor scintigraphy for staging and restaging of neuroendocrine tumors

en: Somatostatin receptor scintigraphy (SRS) using In-DTPA-DPhe-octreotide (pentetreotide) has become an integral part of neuroendocrine neoplasm management. The lack of precise quantification is a disadvantage of SRS. This study aimed to adapt the standardized uptake value (SUV) to SRS, establish the SUV range for physiological uptake in the liver, kidney, and spleen, and elucidate the utility of combined visual and quantitative SRS assessment for staging and restaging of neuroendocrine tumors (NETs). This study included 21 patients with NETs who underwent In-pentetreotide SRS. The SUV of physiological and pathological uptake was calculated using bone single-photon emission computed tomography (SPECT) quantitative analysis software (GI-BONE). For visual analysis, the primary and metastatic lesions were scored visually on planar and SPECT images using a five-point scale. We assessed the relationships between the SUVs of the liver, kidney, and spleen in the dual phase, and among quantitative indices, visual score, and pathological lesions classification. Sixty-three NEN lesions were evaluated. The mean ± standard deviation maximum SUVs (SUVmax) were liver: 4 h, 2.6 ± 1.0; 24 h, 2.2 ± 1.0; kidney: 4 h, 8.9 ± 1.8; 24 h, 7.0 ± 2.0; and spleen; 4 h, 11.3 ± 4.5; 24 h, 11.5 ± 7.6. Higher SUVmax was significantly associated with higher visual scores on dual-phase SPECT (4 h, p < 0.001; 24 h, p < 0.001) (4 h: scores 3 and 4, p < 0.05; scores 3 and 5: p < 0.01; scores 4 and 5: p < 0.01; 24 h: scores 3 and 4, p = 0.0748; scores 3 and 5: p < 0.01; scores 4 and 5: p < 0.01). We adapted the SUV to SRS and established the range of SUV for physiological uptake in the liver, kidney, and spleen. Combined visual and quantitative assessment is useful for imaging individual lesions in greater detail, and may serve as a new tumor marker of SRS for staging and restaging of NETs.

en: Japanese Journal of Radiology

ja: Japanese Journal of Radiology


en: Analysis of the Number and Content of X-ray Examinations in the Oral & Maxillofacial Radiology Department of Tokushima University Hospital over the Past 10 Years

ja: 徳島大学病院歯科放射線科における過去10年間のX線撮影件数・内容の分析

en: Dental Radiology

ja: 歯科放射線


en: Noise Reduction Using Singular Value Decomposition with Jensen-Shannon Divergence for Coronary Computed Tomography Angiography

en: Coronary computed tomography angiography (CCTA) is widely used due to its improvements in computed tomography (CT) diagnostic performance. Unlike other CT examinations, CCTA requires shorter rotation times of the X-ray tube, improving the temporal resolution and facilitating the imaging of the beating heart in a stationary state. However, reconstructed CT images, including those of the coronary arteries, contain insufficient X-ray photons and considerable noise. In this study, we introduce an image-processing technique for noise reduction using singular value decomposition (SVD) for CCTA images. The threshold of SVD was determined on the basis of minimization of Jensen-Shannon (JS) divergence. Experiments were performed with various numerical phantoms and varying levels of noise to reduce noise in clinical CCTA images using the determined threshold value. The numerical phantoms produced 10% higher-quality images than the conventional noise reduction method when compared on a quantitative SSIM basis. The threshold value determined by minimizing the JS-divergence was found to be useful for efficient noise reduction in actual clinical images, depending on the level of noise.

en: Diagnostics

ja: Diagnostics


en: Image reconstruction algorithm using weighted mean of ordered-subsets EM and MART for computed tomography

en: Mathematics

ja: Mathematics


en: Differences in image density adjustment parameters on the image matching accuracy of a floor-mounted kV X-ray image-guided radiation therapy system

en: This study aimed to investigate the effect of two different image density adjustment parameters on the results of image matching at six degrees of freedom using radiographic images generated by the ExacTrac X-ray system in brain stereotactic radiosurgery (SRS). This study comprised 32 patients who underwent brain SRS at our hospital from January 2020 to December 2020. In this study, (1) the default parameter (an image density parameter between "tissue" and "bone") was an image density parameter for digitally reconstructed radiograph (DRR) generation used at many facilities, and (2) the bone parameter was the steepest contrast parameter used at our hospital. Of the 32 patients, 24 (75%) had a couch angle of 0.5 mm or more in the translational direction or 0.5° or more in the rotational direction, and 10 (31%) had a couch angle of 1.0 mm or more in the translational direction or 1.0° or more in the rotational direction. Among the 131 cases of all couch angles, 46 (35%) cases had a translational direction of 0.5 mm or more or a rotational direction of 0.5° or more, and 15 (11%) had a translational direction of 1.0 mm or more or a rotational direction of 1.0° or more. The results of this study indicate the usefulness of using appropriate DRR parameters for each case, rather than using the default settings. The use of appropriate DRR parameters can lead to accurate position matching results, leading to fewer image-guided radiation therapy shots and a lower imaging dose.

en: Journal of Applied Clinical Medical Physics


en: Noise-Robust Image Reconstruction Based on Minimizing Extended Class of Power-Divergence Measures

en: Entropy

ja: Entropy


en: Hybrid Euler method for discretizing continuous-time tomographic dynamical system

en: Journal of Signal Processing

ja: Journal of Signal Processing


ja: Hybrid Euler method for discretizing continuous-time tomographic dynamical system

en: Proc. of NCSP'20

ja: Proc. of NCSP'20


en: Continuous-time image reconstruction based on Hellinger distance minimization for medical X-ray CT imaging

en: Basic & Clinical Pharmacology & Toxicology (Abstracts)


en: Hybrid of ML-EM and MART algorithms for X-ray CT image reconstruction

ja: Basic & Clinical Pharmacology & Toxicology (Abstracts)


en: Hybrid algorithm of maximum-likelihood expectation-maximization and multiplicative algebraic reconstruction technique for iterative tomographic image reconstruction

en: Proceedings Volume 11049, International Workshop on Advanced Image Technology (IWAIT) 2019


en: Direct Dose Measurement of Patients during Pediatric Computed Tomography Examination

en: Progress in Nuclear Science and Technology


en: Tomographic image reconstruction based on minimization of symmetrized Kullback-Leibler divergence

en: Mathematical Problems in Engineering

ja: Mathematical Problems in Engineering

number: No.Article ID 8973131

ending_page: pages


en: Application of Hamiltonian Monte Carlo Method to Metal Artifact Quantitative Evaluation in Computed Tomography (CT)

ja: Computed tomography (CT) で生じる金属アーチファクト定量評価へのハミルトニアンモンテカルロ法の適用

en: In this study, we propose an evaluation method for Bayesian estimation of Gumbel distribution parameters by the Hamiltonian Monte Carlo method (HMC method), with changing the pixel size of the CT image to investigate streak artifacts, without using a significant difference test. Placed a titanium endcap in the center of the CT dose index (CTDI) measurement phantom and got the CT image by changing the display-field of view (D-FOV) to S, M, L, LL. We compared Gumbel distribution parameters with conventional estimation method and Bayesian estimation method using HMC method. In addition, we evaluated streak artifacts by Bayesian statistical analysis. The difference in streak artifact between D-FOV was more than 90% except between D-FOV M and L. The effect of streak artifacts is small as the pixel size was small. By using the HMC method, we can estimate the Gumbel distribution parameters accurately and objectively, and quantitatively evaluated that the streak artifacts differ in pixel size using Bayesian statistical analysis.

en: Japanese Journal of Radiological Technology

ja: 日本放射線技術学会雑誌


en: Basic study for internal dose evaluation during CT examination by means of small-type OSL dosimeter

en: [Aims and objectives] We plan to manage the patient dose exposure during computed tomography (CT) examination using a small-type OSL dosimeter. The OSL dosimeter can measure entrance skin dose (ESD) directly, but the internal dose can't be measured. The aim of this study is to clarify the relationship between the ESD and internal dose during the CT examination. [Methods and materials] We constructed an abdominal phantom, in which OSL dosimeters can be implanted in, and used this phantom to measure external and internal doses during CT examination. The typical irradiation conditions were as follow, 64 rows of detectors, 120 kV, 600 mA, PF (pitch factor) = 1.484 in helical scan mode. Additionally, we analyzed the contribution of X-rays, which were generated from different angles to the dosimeter; namely, angular dependences of 0-360 degrees at 45 degree intervals were evaluated experimentally. [Results] The ESDs and internal doses showed similar values, however the deviations between them were completely different; maximum deviation of ESD was found to be 30% and that of internal dose was at the most 5%. The deviation in ESDs is explained by the phenomenon in which some dosimeters were irradiated by direct X-ray and others were not. However, the small deviation between internal doses was explained by the phenomenon in which dosimeters were mainly irradiated by scattered X-rays. [Conclusion] In this study, we analyzed the relationship between ESD and internal dose for direct dose measurement of patient dose undergoing CT examination. The ESDs show relatively large fluctuations, on the other hand, the internal doses show small deviations.

en: European Congress of Radiology

ja: European Congress of Radiology


en: Numerical Evaluation of Image Contrast for Thicker and Thinner Objects among Current Intraoral Digital Imaging Systems.

en: The purpose is to evaluate the performance of current intraoral digital detectors in detail using a precise phantom and new method. Two aluminum step wedges in 0.5 mm steps were exposed by two photostimulable phosphor plate (PSP) systems-one with automatic exposure compensation (AEC) and the other without AEC-and a CCD sensor. Images were obtained with 3 doses at 60 kV. The effect of metallic material also was evaluated. The contrast-to-noise ratio (CNR) for thinner steps and the low contrast value (LCV) for thicker steps were obtained. The CCD system was the best under all conditions (P < 0.001), although the Gray value was sensitive to the dose, and the Gray value-dose relation varied greatly. The PSP system with AEC was superior to that without AEC for the LCV (P < 0.001) but was inferior to it regarding the CNR (P < 0.001). CNR and LCV in the PSP system without AEC were not affected by the metallic plate. Intraoral digital imaging systems should be chosen according to their diagnostic purpose. PSP system with AEC may be the best for detecting molar proximal caries, whereas the PSP system without AEC may be better for evaluating small bone regeneration in periodontal disease. The CCD system provided the best performance.

en: BioMed Research International

ja: BioMed Research International


en: 口内法X線画像用DICOMファイルの規格化および歯科用Viewerの実用化

ja: 口内法X線画像用DICOMファイルの規格化および歯科用Viewerの実用化

en: Dental Radiology


en: 2種類のデジタル口内法イメージングシステムによるコントラストの比較

ja: 2種類のデジタル口内法イメージングシステムによるコントラストの比較