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排序方式: 共有96条查询结果,搜索用时 31 毫秒
1.
Takanaga M Hayashi N Miyati T Kawashima H Hamaguchi T Ohno N Sanada S Yamamoto T Matsui O 《Nihon Hoshasen Gijutsu Gakkai zasshi》2012,68(3):201-208
Diffusion-weighted imaging (DWI) has been used to characterize not only the brain, but also the breast by implementation of faster imaging techniques and higher magnetic field strengths. However, the optimum b value, which is an important scan parameter for DW images contrast on 3 T breast magnetic resonance imaging (MRI) has not been established. The purpose of this study was to investigate the influence of different b value combinations on the image contrast and apparent diffusion coefficient (ADC) in patients with known invasive carcinoma, ductal carcinoma in situ (DCIS), and normal mammary gland in breast DWI. The analysis procedure consisted of the following methods: 1) T(2) correction of DW images with echo-planar imaging (EPI) T(2)-weighted images; 2) contrast measurement between normal mammary gland and tumor tissues; 3) ADC measurement of normal mammary gland and tumor tissues. In many cases, the highest contrast between normal mammary gland and tumor tissues was obtained using a b value of 1500 s/mm(2). Our results indicated that when only one b value is used, the b value in which signal intensities of normal mammary gland decreases down to noise level, and the contrast between normal mammary gland and tumor tissues is recommended. ADC value decreased with increasing b value. Therefore, when determining the ADC threshold level, it is important to perform the evaluation using ADC values calculated from DW images with the same b value in clinical studies. 相似文献
2.
Kuroiwa Y Nagamachi S Miyati T Yamaguchi K Nishii R Kuga N Azuma T Arita H Maeda M Tamura S Kawai K 《Annals of nuclear medicine》2012,26(2):147-163
Objective
The aim is to compare and evaluate the agreement of quantification of left ventricular functional parameters obtained by two different methods, 99mTc-tetrofosmin gated myocardial perfusion SPECT (MPS) and cardiac magnetic resonance imaging (CMR).Methods
Ten healthy male volunteers participated. Gated MPS data were acquired using 32 frames, which were also combined into 16- and 8-frame data set for the investigation. Gated CMR data were acquired using 8, 16 and 32-frame for the different sets. All examinations were conducted in resting and at exercise conditions. Quantitative measurements of end-diastolic volume (EDV), end-systolic volume (ESV), left ventricular ejection fraction (LVEF), peak ejection rate (PER), peak filling rate (PFR) and time to peak filling (TTPF) were done for each study, respectively. Finally, we evaluated the concordance of parameters between gated MPS and gated CMR by % difference and Bland?CAltman plot analysis.Results
LVEF showed favorable concordance in both rest and exercise conditions (% differences were around 10%). PER, PFR and TTPF also showed good concordances in rest conditions, under 32-frame gated collections particularly (% differences were around 10%). In exercise conditions, although the concordances were relatively good, certain variances were noted (% differences were around 20?C25%). Regarding left ventricular volumes, the concordance were worse in both conditions (% differences were around 30?C40%).Conclusions
In quantifying of left ventricular function parameter, gated CMR provides similar quantitative values comparing with gated MPS except for ventricular volumes in rest conditions. In contrast, there were certain variations except for LVEF in exercised examinations. When we follow patients by the same cardiac parameters with CMR and MPS, using parameters across the two modalities proved to be possible under rest condition. However, it is limited at exercise condition. 相似文献3.
Shintaro Ito Nobukazu Fuwa Miwako Nomura Suguru Ota Takayuki Morishima Takashi Daimon Yoshikazu Maeda Jun Ueda Iwai Tohnai Noriko Ii Tosiaki Miyati 《Auris, nasus, larynx》2021,48(3):496-501
ObjectiveIn cases of head and neck cancer treated with intra-arterial chemotherapy, no objective indices are available for determining the distribution of anticancer drugs administered to multiple arteries. To establish such indices, noninvasive measurements of drug concentrations are required in the arterial perfusion area of each artery. In MRI, changes in 1/T1 (Δ1/T1) are correlated with the contrast agent concentration. We focused on these properties and investigated whether it is possible to estimate anticancer drug concentrations within tissue based on Δ1/T1.MethodsWe employed the fast spin echo (FSE) sequence to determine optimum imaging parameters using a phantom. Subsequently, contrast agent was administered via the lingual and external carotid arteries for seven cases of tongue cancer. Δ1/T1 were then measured in tumor and nontumor tissues. The results of this study were compared with those of a previous study in which intratumor concentrations of anticancer agent were measured in excised specimens.ResultsThe optimum imaging parameters for the FSE was two repetition times (TR, 500 and 1000 ms). When compared with the external carotid artery administration, the lingual artery administration of contrast agent resulted in significantly higher Δ1/T1 in both tumor and nontumor tissues (2.13 and 2.62 times, respectively). The multiplying factor for the nontumor tissue and high homogeneity of the contrast agent concentration were reasonably consistent with the results of the previous study.ConclusionThis method can be applied to estimating intratissue concentrations of intra-arterially administered anticancer drugs, thus possibly providing useful information in determining the distribution of anticancer drugs. 相似文献
4.
Susumu Moriya Yukio Miki Tamotsu Kamishima Tosiaki Miyati Mitsunori Kanagaki Yukako Matsuno Tsuneo Yokobayashi 《European journal of radiology》2013
Objectives
To investigate whether rice pads can eliminate lingering fat signals of the complex surface shape of both hands that occur with chemical shift selective (CHESS) at 1.5 T and 3.0 T.Materials and methods
T1-weighted images were obtained with CHESS using 1.5 T and 3.0 T systems. The same imaging parameters were used with and without rice pads on the coronal plane of both hands in 10 healthy volunteers. The fat-suppression effects were classified into four categories and scored for images, and visual evaluations were performed by one radiologist and one radiologic technologist.Results
At 1.5 T, the mean evaluation score was 1.55 for images obtained without rice pads and 3.50 for images obtained with rice pads. At 3.0 T, the mean evaluation score was 1.10 for images obtained without rice pads and 3.20 for images obtained with rice pads. With both systems, images obtained with the rice pads showed significantly better fat suppression effects than images obtained without rice pads (P < 0.0001, P < 0.0001).Conclusions
It was confirmed that lingering fat signals are eliminated and good fat-suppressed images are obtained with the use of rice pads at 1.5 T and 3.0 T. Rice pads are therefore useful with at 1.5 T and 3.0 T, which are currently becoming more widely used. 相似文献5.
Masami Goto Osamu Abe Shigeki Aoki Naoto Hayashi Tosiaki Miyati Hidemasa Takao Takeshi Iwatsubo Fumio Yamashita Hiroshi Matsuda Harushi Mori Akira Kunimatsu Kenji Ino Keiichi Yano Kuni Ohtomo 《Neuroradiology》2013,55(7):869-875
Introduction
This study aimed to investigate whether the effect of scanner for cortex volumetry with atlas-based method is reduced using Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (DARTEL) normalization compared with standard normalization.Methods
Three-dimensional T1-weighted magnetic resonance images (3D-T1WIs) of 21 healthy subjects were obtained and evaluated for effect of scanner in cortex volumetry. 3D-T1WIs of the 21 subjects were obtained with five MRI systems. Imaging of each subject was performed on each of five different MRI scanners. We used the Voxel-Based Morphometry 8 tool implemented in Statistical Parametric Mapping 8 and WFU PickAtlas software (Talairach brain atlas theory). The following software default settings were used as bilateral region-of-interest labels: “Frontal Lobe,” “Hippocampus,” “Occipital Lobe,” “Orbital Gyrus,” “Parietal Lobe,” “Putamen,” and “Temporal Lobe.”Results
Effect of scanner for cortex volumetry using the atlas-based method was reduced with DARTEL normalization compared with standard normalization in Frontal Lobe, Occipital Lobe, Orbital Gyrus, Putamen, and Temporal Lobe; was the same in Hippocampus and Parietal Lobe; and showed no increase with DARTEL normalization for any region of interest (ROI).Conclusion
DARTEL normalization reduces the effect of scanner, which is a major problem in multicenter studies. 相似文献6.
Masanori Ozaki MS Yusuke Inoue MD PhD Tosiaki Miyati PhD DMSc Hirohumi Hata RT Sinya Mizukami RT Shotaro Komi RT Keiji Matsunaga MD Reiko Woodhams MD PhD 《Journal of magnetic resonance imaging : JMRI》2013,37(1):172-178
Purpose:
To assess the effect of motion artifact reduction on the diffusion‐weighted magnetic resonance imaging (DWI‐MRI) of the liver, we compared velocity‐compensated DWI (VC‐DWI) and VC‐DWI combined with tetrahedral gradients (t‐VC‐DWI) to conventional DWI (c‐DWI) in the assessment of apparent diffusion coefficients (ADCs) of the liver.Materials and Methods:
In 12 healthy volunteers, the liver was scanned with c‐DWI, VC‐DWI, and t‐VC‐DWI sequences. The signal‐to‐noise ratio (SNR) and ADC of the liver parenchyma were measured and compared among sequences.Results:
The image quality was visually better for t‐VC‐DWI than for the others. The SNR for t‐VC‐DWI was significantly higher than that for VC‐DWI (P < 0.05) and comparable to that for c‐DWI. ADCs in both hepatic lobes were significantly lower for t‐VC‐DWI than for c‐DWI (P < 0.01). ADC in the left lobe was significantly lower for VC‐DWI than for c‐DWI (P < 0.01). Although ADC in the left lobe was significantly higher for c‐DWI (P < 0.01), no significant differences in ADCs were found between the right and left lobes for VC‐DWI and t‐VC‐DWI.Conclusion:
The use of a t‐VC‐DWI sequence enables us to correct ADCs of the liver for artificial elevation due to cardiac motion, with preserved SNR. J. Magn. Reson. Imaging 2013;37:172–178. © 2012 Wiley Periodicals, Inc. 相似文献7.
Yasuo Takatsu Kengo Nishiyama Tosiaki Miyati Hideto Miyano Mariko Kajihara Thai Akasaka 《Radiological physics and technology》2013,6(2):486-491
We evaluated the degree of inhomogeneities of fat suppression using the fully automated three-dimensional breast shimming technique (Image Based-Smart: IB-Smart) and manual setting of a rectangular parallelepiped shim (volume shimming) in MR mammography. Information on breast shape was collected from 9 patients whose images were insufficiently fat-suppressed. A breast phantom made of a thermoplastic sheet was used. Shimming of the magnetic field was done with IB-Smart and various dimensions of volume shims: the anterior to posterior/right to left/head to foot directions were set to 75–150/150–350/50–150 mm. The volumes of inhomogeneously suppressed fat were measured. The calculated volume with inhomogeneous fat suppression with use of IB-Smart was 13.3 × 104 mm3. The smallest volume of inhomogeneous fat suppression with volume shimming was 5.4 × 104 mm3 when the anterior–posterior/right–left/head–foot directions were set to 75/350/50 mm. Our results show that using optimized dimensions of volume shims enables better fat suppression than does IB-Smart. 相似文献
8.
9.
Harumasa Kasai Tosiaki Miyati Tatsuya Kawai Hirohito Kan Makoto Kawano Yuta Shibamoto 《Radiological physics and technology》2014,7(2):211-216
Our aim in this study was to create a noninvasive and practical method for evaluating metabolic information on the liver (iron content and lipid infiltration) and spine (bone mineral density and marrow fat degeneration) using double gradient-echo with and without the spectral fat suppression technique (double-GRE–FS). We arranged phantoms made of various concentrations of superparamagnetic iron oxide solution adjacent to neutral fat to obtain slice planes with various fat fractions using the partial volume effect. We obtained double-GRE–FS images and calculated the T2* values. The fat fraction was calculated from signal intensities of double-GRE–FS images after T2* decay, baseline, and slope corrections. We assessed the fat fraction and the relationship between R2* of the water component and the iron concentration. In addition, we evaluated those values in human bone marrow and liver, including a patient with liver steatosis. The actual fat fraction value was consistent with the fat fraction obtained with the double-GRE–FS method, and the calculated fat fraction was unaffected by the iron concentration. There was a strong positive correlation between R2* of the water component and the iron concentration. There was a negative correlation between the fat fraction and the bone mineral density, and the R2* was correlated with the bone mineral density. The calculated fat fraction in the liver steatosis patient was significantly higher than that in healthy volunteers. The double-GRE–FS makes it possible to assess the fat fraction and R2* simultaneously, and to obtain metabolic information on the liver and bone marrow. 相似文献
10.
Dermatophagoides-induced interleukin-10 production by peripheral blood lymphocytes from patients with asthma in remission 总被引:1,自引:0,他引:1
Takeshi Noma Yoko Sugawara Norifumi Ogawa Tosiaki Saeki Koichi Yamaguchi Yutaka Kawano 《Pediatric allergy and immunology》2004,15(5):459-468
Interleukin (IL)-10 is a cytokine that regulates inflammatory responses. We studied the role of IL-10 in the development of tolerance to Dermatophagoides farinae in asthma patients in remission, since asthma improves in most children during adolescence. The spontaneous production of IL-10 by cultured peripheral blood mononuclear cells (PBMC) was higher in patients with active asthma than in normal subjects. IL-10 production decreased when 1 microg/ml D. farinae was added to cultures, but increased again in a dose-dependent manner when higher concentrations of D. farinae were added. In patients with remission of asthma, IL-10 production was lower than in patients with active asthma. However, production of IL-10 showed a reciprocal increase in the presence of 1 microg/ml D. farinae, and decreased again at 10 and 50 microg/ml D. farinae. Such alterations were not observed in normal subjects. Cell lines established from patients asthma in remission showed higher IL-10 production when compared with that by cell lines from normal subjects or patients with active asthma when the cells were stimulated by D. farinae at 1 or 10 microg/ml. Neutralization of IL-10 led to revival of the D. farinae-specific proliferative response of PBMC from patients in remission, which was otherwise decreased. The increase of IL-10 production stimulated by D. farinae was inhibited by addition of an anti-IL-10 antibody. In contrast, antigen-induced interferon (IFN)-gamma production, which was increased by D. farinae stimulation when patients were in remission, did not increase after treatment with anti-IL-10, although spontaneous IFN-gamma production increased to the level seen after D. farinae stimulation. The reduced IL-4 production by cells from patients in remission after stimulation with D. farinae antigen, which was significantly higher in active patients, was not reversed by neutralization of IL-10. The D. farinae-induced IL-10/IL-4 production ratio, but not the IL-10/IL-5 production ratio, may be a significant indicator for evaluation of whether a patient has been in remission. In conclusion, D. farinae-specific anergy of T cells is likely to be induced by increased levels of IL-10 and IFN-gamma that are initially produced by specific T cells after exposure to relevant mite allergen in patients in remission. 相似文献