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Idiopathic normal pressure hydrocephalus (iNPH), a syndrome characterized by cognitive impairment, gait abnormalities, and urinary incontinence attributable to cerebrospinal fluid circulatory insufficiency, is associated with an obscure etiology. Several methodologies and imaging analysis techniques, including visualization of cerebral hemodynamics and diffusion tensor imaging have emerged in recent years to determine functional alterations in cases of iNPH. These advancements have led to more comprehensive understanding of the pathophysiological mechanisms underlying iNPH. In this article, we discuss the historical evolution of imaging modalities for iNPH and contemporaneous imaging techniques designed to acquire deeper insight into this disease.

We report a case of left-handed bilingual aphasia with phonemic paraphasia and language mixing from Japanese as a first language to English as a second language. The lesion caused by cerebral infarction was mainly localized in the left parietal lobe white matter. The patient was a 46-year-old, left-handed woman who was bilingual in Japanese and English. Both auditory and visual comprehensions were well maintained after the acute phase of the disease; however, language mixing between Japanese and English was observed during Japanese speech. A pathophysiological interpretation of this case required a focus on the brain network. Our findings suggest that lesions of the superior longitudinal fasciculus and arcuate fasciculus of the white matter fibers just below the left inferior parietal lobule are associated with bilingual aphasia.

Kumar defined duropathies as disorders with dural defects-related cerebrospinal fluid leaks, particularly of spinal anterior dura mater, Superficial (hemo) siderosis (SS) and multisegemental amyotrophy (MSAM) were included in duropathies. Dural defects of SS had two types; one was incomplete closure of the dura in the spinal and cranial operations, the other was a spontaneous defect in the spinal anterior dura mater. In a majority of SS patients, spontaneous dural defects were detected at the levels of C7/Th1 to Th2/Th3 on axial FIESTA (fast imaging employing steady state acquisition) images. Similarly, dural defects in our 6 cases with MSAM were showed at C7/Th1 to Th2/Th3. Axial FIESTA images were crucial on MR imaging. T 2 weighted images demonstrated abnormal hyperintense lesions in both anterior horns at the level of C3 spinal cord in all of 7 patients with MSAM. A dural defect in one case was not found.

Surfer's myelopathy is non-traumatic spinal cord injury which develops in beginner surfers. The patient was a 17-year-old female who developed severe paraplegia with bilateral sensory dysfunction below the groin and bladder/rectal dysfunctions after her first surfing lesson. A spinal-cord MRI performed six hours after onset revealed an intramedullary hyperintensity area from T8 to the conus medullaris on the T 2 weighted images. Expansion of this hyperintensity area was observed on Day 3 and showed a reduction on Day 8. After providing intravenous methylpredonisolone, intravenous glycerol and intravenous edaravone, motor function and bladder/rectal functions began to improve after approximately three weeks. In this study, the expansion of the lesion in the early stages of the disease course was observed by sequential spinal MRI. Furthermore, a time lag between improvement according to imaging and improvement in symptoms was also observed.

Diffusion tensor imaging (DTI) of skeletal muscles has been reported as capable to characterize physiological properties, tissue microstructure and architectural organization. However, the DTI indices may vary with the contractile state of the muscles, and in the rotator cuff muscles, a change in forearm position can result in variation of the DTI indices. The purpose of this study was to examine the influence of forearm position on the major DTI indices of the rotator cuff muscles. The DTI of right rotator cuff was acquired under the neutral position and external and internal rotation of the forearm in nine healthy volunteers. Fractional anisotropy (FA) and mean diffusivity (MD) of each muscle were calculated and compared among the three forearm positions. FA and MD were significantly different between external and internal rotation in infraspinatus, teres minor and subscapularis (p<0.05). We considered that this difference was due to the change in cross-sectional area of muscle fibers based on their contractile state. That is, when the muscle is contracted, its cross-sectional area is increased and the muscle fiber density in the short axis direction becomes less. This causes a change in FA and MD due to increase in λ 2 and λ 3 through increased diffusion of intercellular water in the short axis direction. In conclusion, the DTI indices of the rotator cuff muscles are affected by the forearm position.

The magnetic resonance imaging (MRI) is established as the imaging technique that is essential to the imaging of the central nervous system disease. Above all, the diffusion weighted image (DWI) is known as the tool which can diagnose acute ischemic stroke with high accuracy in a short time. DTI, an applied form of DWI, was devised as a technique to image the structure of the brain white matter. In clinical sites, this technique is used for pathologic elucidation such as the intracerebral tissue injury or mental disorder. Additionally, diffusion tensor tractography (DTT), which is a technique to build three-dimensional structure of the neural fiber tracts, is used for grasping the relations between a brain tumor and the fibers tract. Therefore, these techniques may be useful imaging tools in the central nerve region.

Objective: We performed diffusion tensor imaging (DTI) in children with periventricular leukomalacia (PVL) to quantify the relationship between the fractional anisotropy (FA) values of DTI and the severity of PVL., Methods: In this study, we performed DTI in 16 children (seven males, nine females) with PVL. To evaluate the FA values, we used region-of-interest (ROI) measurements and tractography-based measurements. We classified the patients into two groups based on the severity of the magnetic resonance imaging (MRI) findings: the mild group had white matter injury limited to a triangular zone around the lateral ventricle (n = 9) and the severe group had it extended forward (n = 7). Then, we performed ROI measurements for these two groups to evaluate the FA values. We also divided the patients into two groups based on their motor ability :those that could (n = 10) and could not (n = 6) stand. We used tractography-based measurements to evaluate the FA values. To reduce the bias caused by age, we divided the patients into two groups: those younger than 3 years and those 3 years of age and older. All data were analyzed using the Mann-Whitney U-test, and p < 0.05 was considered statistically significant., Results: In the ROI measurements, regardless of age, the severe group showed a more significant FA reduction in the white matter of the parietal and occipital lobes, including the middle/posterior part of the centrum ovale, superior longitudinal fasciculus, arcuate fascicullus, and thalamic radiation. In the tractography-based measurements, regardless of age, the measured FA values were significantly lower in the group that could not stand., Conclusions: This study suggested that the measured FA values could be used to evaluate the severity of PVL quantitatively, and that DTI provides much more information for understanding the pathophysiology of PVL, as compared with conventional MRI.

The evaluation of human brain maturation in vivo is a significant problem for pediatric neurologists. MRI, especially Diffusion Tensor Imaging (DTI) and (1)H-MR Spectroscopy (MRS), can be a powerful method to solve this problem. A decrease in three eigenvalues (Δλ1 < Δλ2 ≒ Δλ3) and an increase in Fractional Anisotropy, as a function of brain maturation, was identified in the frontal and parietal white matter using DTI, which is a non-invasive imaging technique capable of providing a quantitative view of neural fibers and micro-environmental alterations during the myelination period.MRS, a powerful technique capable non-invasively quantifying N-acetyl-aspartate (NAA), a marker for neurons, glutamate (Glu), an excitatory neurotransmitter, and creatine (Cr), revealed a decrease in the Glu/Cr ratio, but found no changes to the NAA/Cr ratio with maturational changes in brain networks, such as a decrease in cortical synaptic density (refinement).Therefore, we suggest these two MRI techniques, DTI and MRS, can be used to provide direct, non-invasive information on brain maturation in vivo, which we believe will help elucidate the pathophysiology behind neurodevelopmental disorders that disrupt normal brain maturation.

The fractional anisotropy (FA) is calculated by using diffusion tensor imaging (DTI) with multiple motion probing gradients (MPG). While FA has become a widely used tool to detect moderate changes in water diffusion in brain tissue, the measured value is sensitive to scan parameters (e.g. MPG-direction, signal to noise ratio, etc.). Therefore, it is paramount to address the reproducibility of DTI measurements among multiple centers. The purpose of this study was to assess the inter-center variability of FA. We studied five healthy volunteers who underwent DTI brain scanning three times at three different centers (I-III), each with a 1.5 T scanner having a different MPG-schema. Then, we compared the FA and eigenvalue from the three centers measured in seven brain regions: splenium of corpus callosum (CCs), genu of corpus callosum (CCg), putamen, posterior limb of internal capsule, cerebral peduncle, optic radiation, and middle cerebellar peduncle. At the CCs and CCg, there was a statistical difference (p<0.05) between center Iand center IIfor the same MPG-directions. Furthermore, at CCs and CCg, there was a statistical difference (p<0.05) between center II and center III for different MPG-directions. Conversely, no statistical differences were found between center I and center III for the different MPG-directions for all regions. These results indicate that the FA value was affected by the MPG-schema as well as by the MPG-directions.

Diffusion tensor imaging (DTI) is an MRI modality used to measure the thermal motion of water molecules by combining the measured water diffusion with a simple tensor model of a 3 × 3 symmetric matrix. Since there are many structures that restrict the free motion of water molecules in the brain, we can use the diffusion property of water to study the brain anatomy. Because DTI can provide directional information about axonal fiber bundles, this technique may be one of the most effective MR tools for the investigation of the human white matter anatomy in vivo. Along with the qualitative analysis of fiber pathways using tractography, the quantitative analysis using DTI enables researchers to investigate relationships between white matter anatomy and brain functions as well as to identify tract-specific developmental patterns or disease-specific alterations of the fiber tracts. Several methods have been proposed for whole-brain DTI analysis without an a priori hypothesis. Voxel-based analysis (VBA) is one of the most widely used approaches, although it has concerning limitations, especially when isotropic spatial smoothing is applied. Alternative methods such as tract-based spatial statistics and atlas-based analysis have been introduced to overcome the limitations of VBA. Future studies combining the anatomical connectivity illustrated by using DTI and the functional connectivity illustrated by using resting-state fMRI will provide an emerging landscape of human brain connectivity.