Publications by authors named "Atsushi Takemura"

The Wnt/β-catenin signaling pathway plays crucial roles in embryonic development and the development of multiple types of cancer, and its aberrant activation provides cancer cells with escape mechanisms from immune checkpoint inhibitors. E7386, an orally active selective inhibitor of the interaction between β-catenin and CREB binding protein, which is part of the Wnt/β-catenin signaling pathway, disrupts the Wnt/β-catenin signaling pathway in HEK293 and adenomatous polyposis coli ()-mutated human gastric cancer ECC10 cells. It also inhibited tumor growth in an ECC10 xenograft model and suppressed polyp formation in the intestinal tract of mice, in which mutation of activates the Wnt/β-catenin signaling pathway.

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Computed DWI (cDWI) is a mathematical technique that calculates arbitrary higher b value images from at least two different lower b values. In addition, the removal of high intensity noise with image processing on cDWI could improve cholesteatoma-background contrast-to-noise ratio (CNR). In the present study, noise reduction was performed by the cut-off values of apparent diffusion coefficient (ADC) less than 0 and 0.

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The two-dimensional Cartesian turbo spin-echo (TSE) sequence is widely used in routine clinical studies, but it is sensitive to respiratory motion. We investigated the k-space orders in Cartesian TSE that can effectively reduce motion artifacts. The purpose of this study was to demonstrate the relationship between k-space order and degree of motion artifacts using a moving phantom.

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Purpose: The purpose of this study was to compare scan time and image quality between magnetic resonance angiography (MRA) of the thoracic aorta using a multi-shot gradient echo planar imaging (MSG-EPI) and MRA using balanced steady-state free precession (b-SSFP).

Materials And Methods: Healthy volunteers (n=17) underwent unenhanced thoracic aorta MRA using balanced steady-state free precession (b-SSFP) and MSG-EPI sequences on a 3T MRI. The acquisition time, total scan time, signal-to-noise ratio (SNR) of the thoracic aorta, and the coefficient of variation (CV) of thoracic aorta were compared with paired t-tests.

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Purpose: To optimize the flip angle (FA) of the T enhanced spin-echo imaging using the time reversed gradient echo (T2FFE) and evaluate its utility for differentiating hypointensity nodules in the hepatobiliary phase (HBP) of gadoxetic acid-enhanced (Gd-EOB) MRI.

Materials And Methods: First, FA optimization of the T2FFE in the HBP was investigated by comparing signal-to-noise ratio (SNR) among different FAs using phantoms. The liver-to-muscle contrast ratios (CR) and image quality among three FAs (20°, 50° and 80°) were compared using images of 10 patients.

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Purpose: To compare the abilities of turbo spin-echo diffusion-weighted imaging (TSE DWI) and multi-shot echo planar DWI (MSh DWI) to discriminate orbital lymphoma from inflammatory lesions.

Materials And Methods: Twenty-nine patients with pathologically confirmed lymphomas and 39 patients with inflammation were imaged with a 3.0-T system.

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Purpose: We investigated the feasibility of single breath hold unenhanced coronary MRA using multi-shot gradient echo planar imaging (MSG-EPI) on a 3T-scanner.

Methods: Fourteen volunteers underwent single breath hold coronary MRA with a MSG-EPI and free-breathing turbo field echo (TFE) coronary MRA at 3T. The acquisition time, signal to noise ratio (SNR), and the contrast of the sequences were compared with the paired t-test.

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Aim: To retrospectively evaluate the diagnostic performance of free-breathing diffusion-weighted imaging (FB-DWI) with modified imaging parameter settings for detecting hepatocellular carcinomas (HCCs).

Methods: Fifty-one patients at risk for HCC were scanned with both FB-DWI and respiratory-triggered DWI with the navigator echo respiratory-triggering technique (RT-DWI). Qualitatively, the sharpness of the liver contour, the image noise and the chemical shift artifacts on each DWI with -values of 1000 s/mm were independently evaluated by three radiologists using 4-point scoring.

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Purpose: Quantification of myocardial oxygenation (MO) in heart failure (HF) has been less than satisfactory. This has necessitated the use of invasive techniques to measure MO directly or to determine the oxygen demand during exercise using the cardiopulmonary exercise (CPX) test. We propose a new quantification method for MO using blood-oxygen-level-dependent (BOLD) myocardial T2* magnetic resonance imaging (M-T2* MRI), and investigate its correlation with CPX results.

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In this study, three-dimensional phase contrast magnetic resonance imaging (3D-PC MRI), a novel technique, was validated to assess pulmonary artery (PA) flow in patients with chronic thromboembolic pulmonary hypertension (CTEPH). The MR data of PAs from 3D-PC and two-dimensional PC (2D-PC) from before and after treatment for 3 patients with CTEPH were retrospectively analyzed. Additionally, 3D- and 2D-PC MR scans of PA were performed in 5 healthy volunteers.

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Purpose: To evaluate the image quality and acquisition time of magnetic resonance cholangiopancreatography (MRCP) with and without the 3D hybrid profile order technique.

Materials And Methods: We studied 32 consecutive patients at 3T. They underwent MRCP with and without the 3D hybrid profile order imaging technique during free breathing and MRCP with the 3D hybrid profile order technique during a single breath-hold.

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Purpose: We compared the image quality of free-breathing diffusion-weighted imaging (FB-DWI) to that of respiratory-triggered DWI (RT-DWI) after proper optimization.

Materials And Methods: Three healthy subjects were scanned to optimize magnetic resonance (MR) parameters of FB-DWI to improve image quality, including spatial resolution, image noise, and chemical shift artifacts. After this optimization, we scanned 32 patients with liver disease to assess the clinical feasibility of the optimized FB-DWI.

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We demonstrated a new scheme for performing the T1-enhanced whole-brain black-blood imaging pulse sequence using motion-sensitized driven-equilibrium prepared 3-dimensional (3D) turbo spin echo (MSDE-TSE) with anti-driven-equilibrium post pulse. The use of an anti-driven-equilibrium pulse considerably improved the T1 contrast of MSDE-TSE black-blood images. This sequence can be used for whole-brain 3D volumetric T1-weighted black-blood imaging and may improve the accuracy of anatomical localization for certain brain lesions.

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The aim of this study was to use T2* cardiac magnetic resonance (CMR) imaging to quantify myocardial iron content in patients with heart failure (HF) and to investigate the relation between iron content, cardiac function, and the cause of HF. CMR data were analyzed from 167 patients with nonischemic and 31 with ischemic HF and 50 patients with normal ventricular function. Short-axis T2* imaging was accomplished using 3-T scanner and multiecho gradient-echo sequence.

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Purpose: To assess the clinical utility of tissue-specific variable refocusing flip-angle (VRFA) turbo-spin echo imaging for three-dimensional T2-weighted imaging (3D-T2WI) of the liver.

Materials And Methods: Fifty-nine patients were scanned with three types of fat-suppressed T2WI for the comparison: two-dimensional single-shot turbo spin echo T2WI (ssT2WI), 3D-T2WI with tissue-specific VRFA (VISTA-TSV), and 3D-T2WI with low-constant VRFA (VISTA). Qualitatively, artifacts in the left and right lobes of the liver and black-blood effects in the liver were compared using the Wilcoxon signed-rank test with the Bonferroni correction.

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We propose a simple scheme of 3D turbo spin echo (TSE) with low-refocusing flip angles (RFAs) for obtaining sufficient T1-weighted contrast. The low RFA can easily lead spins into a pseudo-steady-state (PSS) condition, but a preparation scheme is required for smooth transition into static PSS. For obtaining T1 contrast, PSS preparation is the most important factor, and therefore we focused on the PSS preparation.

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In contrast-enhanced (CE) brain metastasis screening, coexistence of enhanced blood vessel suppression and higher tumor-to-parenchyma contrast may improve radiologists' performances in detecting brain metastases compared with conventional sequences. In this study, we propose a new scheme, allowing both suppression of blood signals and improvement of tumor-to-parenchyma contrast, using motion-sensitized driven equilibrium prepared 3D low-refocusing flip-angle turbo spin echo (TSE) ("magnetization transfer prepared spin echo"-like contrast volume examination: MATLVE) for brain metastasis screening at 3.0 T, and we compare MATLVE to conventional three-dimensional (3D)-gradient recalled echo (GRE) and 3D-TSE sequences.

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We demonstrate the feasibility of the vessel-selective, non-contrast, time-resolved magnetic resonance angiography (MRA) technique, "contrast inherent inflow enhanced multi-phase angiography combining vessel-selective arterial spin labeling technique (CINEMA-SELECT)". This sequence consists of two major techniques: pulsed star labeling of arterial regions (PULSAR) and Look-Locker sampling. We hypothesize that this technique allows selective labeling of single intracranial arteries, consisting of high-resolution four-dimensional data with a wide coverage of the brain.

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T₂-fast field echo (T2FFE) sequence is a rapid T₂-weighted steady state free precession sequence, but has not become a widely utilized MR-imaging strategy because of its low signal-to-noise ratio and high sensitivity to motion. These effects have seriously limited the clinical use of T2FFE and therefore T2FFE has not been used for routine clinical studies. Nevertheless, in this study, we have investigated the possibility of clinical application by re-optimization of the T2FFE on the current MRI systems.

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Detailed information on anatomy and hemodynamics in cerebrovascular disorders such as AVM and Moyamoya disease is mandatory for defined diagnosis and treatment planning. Arterial spin labeling technique has come to be applied to magnetic resonance angiography (MRA) and perfusion imaging in recent years. However, those non-contrast techniques are mostly limited to single frame images.

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3D rapid acquisition with relaxation enhancement or turbo spin-echo sequence is promising for black-blood angiography. In this paper, we propose a new scheme of sequence parameter optimization for "flow-void enhanced" volumetric black-blood angiography. Although black-blood imaging has numerous applications, we focused on the carotid artery in this study.

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Purpose: A cost-sensitive extension of AdaBoost based on Markov random field (MRF) priors was developed to train an ensemble segmentation process which can avoid irregular shape, isolated points and holes, leading to lower error rate. The method was applied to breast tumor segmentation in ultrasonic images.

Methods: A cost function was introduced into the AdaBoost algorithm that penalizes dissimilar adjacent labels in MRF regularization.

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This paper proposes a novel algorithm to estimate a log-compressed K distribution parameter and presents an algorithm to discriminate breast tumors in ultrasonic images. We computed a total of 208 features for discrimination, including those based on a parameter of a log-compressed K-distribution, which quantifies the homogeneity of the echo pattern in the tumor, but is influenced by compression parameters in the ultrasonic device. The proposed algorithm estimates the parameter of the log-compressed K-distribution in a manner free from this influence.

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Objective: Although coronary arterial lesions due to Kawasaki disease (KD) should be evaluated as early as possible after the acute phase, conventional X-ray coronary angiography poses high risks for young children with the disease. The use of noninvasive MR coronary angiography is desirable, although it is difficult to produce clear images in young children. We developed a method to improve the quality of MR coronary angiography in young children.

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