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- 1999 Conference Abstracts
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- 中井敏晴
- Enhanced BOLD contrast in fMRI by using navigator echoes and spatial realignment on 3.0T MRI system
- The advantages of higher field strength in fMRI studies are the better SNR and higher sensitivity to BOLD signal from capillary level. We compared the effects of correction by navigator echoes and spatial realignment using finger movement tasks.Their synergistic effects on the quality of the fMRI data obtained by spiral k-space trajectory sequence at 3.0T were evaluated. The usage of navigator echoes was effective in increasing the cluster size of the activation by two to three fold enhancing the maximum Z score and reducing artifacts. Realignment was mostly effective in reducing artifacts and increasing the cluster size to some extent. Without navigator echoes and realignment, major motion artifacts appeared in 3 of the 12 data sets, which could be removed by combining both methods. ANOVA indicated that there were no interactions between the application of the two methods, and suggested that the confounds removed by each method were different. Navigator echoes were effective to make the most of the higher BOLD contrast obtained by spiral k-trajectory sequence on a high field magnet.
- 杉尾武志
- The role of the posterior parietal cortex in human object recognition: a functional magnetic resonance imaging study
- The mechanisms involved in visual object recognition from non-canonical viewpoints were investigated using functional magnetic resonance imaging (fMRI). We used a passive observation task and found three areas activated more strongly in the non-canonical viewing condition compared with the canonical viewing condition. First, it was found that the fusiform gyrus and posterior part of the inferior temporal cortex were involved in the processing of shape information. Next, it was found that the posterior parietal cortex, mainly the superior parietal lobule and the ventral part of premotor area were involved in visuospatial processing and accessing sensorimotor knowledge. These results may indicate that recognition from non-canonical viewpoints is supported by using functional properties of the object, which require more real-time processing for object manipulation.
- 中井敏晴
- Evolution of magnetic resonance technologies from NMR to MRI, and toward fMRI; Their medical applications
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- 加藤知佳子
- Involvement of motor cortices in retrieval of kanji studied by functional MRI
- Functional magnetic resonance imaging was successfully used to study the activation of the motor cortices during retrieval of japanese ideogram, kanji. The subjects performed kanji completion tasks to generate a kanji in response to an element which is always written first. In most of the subjects,the contralateral premotor cortex, the presupplementary motor area(pre-SMA) and the bilateral intraparietal sulcus were activated during retrieval of kanji without actual writing nor intentional mental writing. Activation associated with actual writing was shown in the contralateral primary sensorimotor cortex and the SMA proper. These results suggested that retrieval of kanji would share the neural basis of motor representation with writing of kanji except for regions directly working for motor output.
- 中井敏晴
- A functional magnetic resonance imaging study of listening comprehension of languages in human at 3 tesla-comprehension level and activation of the language areas
- Passive listening comprehension of native and non-native language was investigated using high resolution functional magnetic resonance imaging (fMRI) at a static magnetic field strength of 3 tesla. Wernicke’s area was activated by comprehensive and non-comprehensive languages indicating that this area is associated with common phonological processing of language. The task with comprehensive but non-native language activated Broca’s area and angular gyrus most frequently. The activations in these areas may be related to demand in semantic and syntactic processing in listening comprehension. Supplementary motor area and pre-motor area were activated by comprehensive languages but not by non-comprehensive language. These motor controlling areas may be involved in semantic processing. Listening to comprehensive but non-native language seems to demand more networked co-processing.
- 黒田輝
- Temperature mapping using the water proton chemical shift: Self-referenced method with echo-planar spectroscopic imaging
- An echoplanar spectroscopic imaging (EPSI) method of temperature mapping is proposed. This method is sufficiently faster than the so-called three-dimensional magnetic resonance spectroscopic imaging(3D-MRSI) method and does not require image subtractions unlike the 'conventional' phase mapping method when an internal reference signal is detectable. The water proton chemical shift measured by using the tissue lipid as an internal reference clearly visualized the temperature change in a porcine liver sample in vitro. It was also demonstrated that the internally referenced EPSI method could markedly reduce a temperature error caused by a simple, translational motion between scans compared with the phase mapping method.
- 新津守
- High-resolution MR imaging of the knee at 3T
- Purpose. To examine the 3.0-T MR unit to obtain high quality, high-resolution images of the knee joint. Subjects and Methods. One human cadaveric and five porcine knees were imaged with the 3.0-T unit. Sets of T1-weighted spin echo images were obtained with in-plane resolution of 0.195 x 0.39 mm and an acquisition time of approximately 5 min. Two porcine knees were also imaged with the 1.0-T unit with an identical imaging protocol and the signal-to-noise ratios were measured on both images at 3 T and 1T. Results. The 3-T MR system provided detailed delineation of the knees. Deep layers of the medial collateral ligament and associated fine fibers beneath the medial and lateral collateral ligament were demarcated. Precise demonstration of the tibial attachment of the anterior cruciate ligament,irregularity of the meniscal free edge, and conjoint tendon formation together with the lateral collateral ligament and the biceps femoris tendon, were demonstrated. Compared to 1-T unit, the signal-to-noise ratio with 3-T was increased by a factor of 1.39 to 1.72. Conclusion. Due to the potential advantage of obtaining detailed images, the 3-T MR system suggests practical utility for fine demonstration of the knee morphology.