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Purpose The purpose of this study was to evaluate whether deep learning reconstruction (DLR) improves the image quality of intracranial magnetic resonance angiography (MRA) at 1.5 T. Materials and methods In this retrospective study, MRA images of 40 patients (21 males and 19 females; mean age, 65.8 ± 13.2 years) were reconstructed with and without the DLR technique (DLR image and non-DLR image, respectively). Quantitative image analysis was performed by placing regions of interest on the basilar artery and cerebrospinal fluid in the prepontine cistern. We calculated the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) for analyses of the basilar artery. Two experienced radiologists evaluated the depiction of structures (the right internal carotid artery, right ophthalmic artery, basilar artery, and right superior cerebellar artery), artifacts, subjective noise and overall image quality in a qualitative image analysis. Scores were compared in the quantitative and qualitative image analyses between the DLR and non-DLR images using Wilcoxon signed-rank tests. Results The SNR and CNR for the basilar artery were significantly higher for the DLR images than for the non-DLR images (p p p p = 0.072–0.565), were also significantly higher for the DLR images than for the non-DLR images. Conclusion DLR enables the production of higher quality 1.5 T intracranial MRA images with improved visualization of arteries.

Previous studies revealed a correlation between local brain volume and cognitive function. The aim of the present study was to investigate the correlation between local gray matter volume and the Wechsler Memory Scale-Revised (WMS-R) logical/verbal memory (WMS-R-verbal) score in healthy adults using a 3 Tesla magnetic resonance scanner and voxel-based morphometry (VBM). T1-weighted magnetic resonance images were obtained in 1,169 healthy adults. The T1-weighted images in native space were bias-corrected, spatially normalized, and segmented into gray matter, white matter, and cerebrospinal fluid images with Statistical Parametric Mapping 5. To investigate regionally the specific effects of the WMS-R-verbal score on the gray matter images, simple regression analysis was performed by VBM treating age, total intracranial volume, and gender as confounding covariates. A P value of less than 0.05 corrected with false discovery rate in voxel difference was considered to be statistically significant. Our study showed a significant positive correlation between the WMS-R-verbal score and the bilateral entorhinal cortex volume. In the right entorhinal, T value is 4.75, and the size of the clusters is 155 voxels. In the left entorhinal, T value is 4.08, and the size of the clusters is 23 voxels. A significant negative correlation was not found. To our knowledge, this is the first VBM study showing that entorhinal cortex volume is positively correlated with the WMS-R-verbal score for healthy subjects. Therefore, in our structural neuroimaging study, we add evidence to the hypothesis that the entorhinal cortex is involved in verbal memory processing.

Introduction Diffusion tensor imaging (DTI) has provided important insights into the neurobiological basis for normal development and aging and various disease processes in the central nervous system. The aim of this article is to review the current protocols for DTI acquisition and preprocessing and statistical testing for a voxelwise analysis of DTI, focused on statistical parametric mapping (SPM) and tract-based spatial statistics (TBSS). Methods We tested the effects of distortion correction induced by gradient nonlinearity on fractional anisotropy (FA) maps or FA skeletons processed via two SPM-based methods (coregistration and FA template methods), or TBSS-based method, respectively. Results With two SPM-based methods, we found similar results in some points (e.g., significant FA elevation for uncorrected images in anterior-dominant white matter and for corrected images in bilateral middle cerebellar peduncles) and different results in other points (e.g., significantly larger FA for corrected images with coregistration method, but significantly smaller with FA template method in bilateral internal capsules, extending to corona radiata, and semioval centers). In contrast, there was no area with significant difference between uncorrected and corrected FA skeletons with TBSS-based method. Conclusion The discrepancy among these results was not explained in full, but possible explanations were misregistration and smoothing for the SPM-based methods and insensitivity to FA changes outside the local centers of white matter bundles for TBSS-based method.

The aim of this study was to evaluate the usefulness of periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER)-based diffusion tensor fiber tractography (DTT) at 3T to visualize infratentorial small fiber structures that cannot be visualized adequately using a conventional single shot echo planar imaging (ssEPI)-based pulse sequence.Four healthy male volunteers were examined in this study. Diffusion tensor images were acquired on a 3T clinical magnetic resonance scanner using PROPELLER and echo planar imaging sequences in six motion-probing gradient orientations. Fiber tracking results for the trigeminal and auditory nerves were compared quantitatively.The trigeminal nerve tract was successfully reconstructed using both acquisition methods (100%). Among these reconstructed tracts, 62.5% of the tracts on PROPELLER-DTT and 25% on ssEPI-DTT were followed to branches beyond the trigeminal ganglion. The reconstructed auditory nerve tract could be identified on PROPELER-DTT (62.5%), whereas no tract or only a short tract was obtained on ssEPI-DTT (37.5%).3T PROPELLER-DTT is useful for visualizing infratentorial small neurofiber structures.

The fractional anisotropy (FA) value calculated by diffusion tensor MRI can indicate the degree of directionality of water diffusion in astrocytic tumors. Here, we report a case of anaplastic astrocytoma in which FA proved invaluable for the preoperative differential diagnosis. A 60-year-old man complained of headache, and underwent routine neuroimaging and DTI. The routine images suggested a low-grade glioma in the left temporal lobe, based on lack of enhancement on MRI with contrast medium and lack of tumor staining on angiograms, whereas FA value was very high. Based on these findings, a preoperative diagnosis of high-grade glioma was suspected. The surgical specimen exhibited the histological features of anaplastic astrocytoma with a high density of spindle shaped cells and low vascularity. In this report, we discuss the relationship between FA and other characteristics of the present tumor, and discuss the utility of FA measurement in astrocytic tumors.

In vivo, water diffusion displays directionality due to presence of complex microstructural barriers in tissue. The extent of directionality of water diffusion can be expressed as a fractional anisotropy (FA) value, using diffusion tensor MR imaging (DTI). The aim of this study was to determine whether FA values indicate microstructures in astrocytic tumors. We performed DTI in 31 patients with astrocytic tumor, and measured the FA values of tumor and normal brain regions prior to CT-guided stereotactic biopsy. After biopsy, FA values were compared to assess the cellularity and vascularity of tumor tissue. Although mean FA values trended to differ among histological types, all mean tumor FA values were lower than those of normal brain regions. Positive correlation was observed between FA values and both cellularity (r = 0.65, p < 0.05) and vascularity (r = 0.45, p < 0.05). We had hypothesized that the FA value of an astrocytic tumor would be determined by a balance between factors increasing the directionality of water diffusion, such as high cellularity and/or vascularity, and factors decreasing the directionality of water diffusion, such as fiber destruction. However, our results suggest that the FA values of glioblastoma, anaplastic astrocytoma, diffuse astrocytoma and pilocytic astrocytoma are largely affected by cellularity and/or vascularity, whereas that of gliomatosis cerebri are largely affected by the preservation of nerve fibers. Measurement of FA value using DTI will allow prediction of histological characteristics such as cellularity, vascularity and/or fiber structure in astrocytic tumors.