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Proton magnetic resonance spectroscopy( 1 H-MRS)is a non-invasive method for evaluating brain function and metabolism. 1 H-MRS can quantify low-molecular-weight metabolites in a living brain; it shows their spectra without tracer administration. In this paper, we introduce 1 H-MRS and MRS for imaging the distribution of metabolites. The applications of 1 H-MRS imaging for several neurological disorders will be outlined.

Many of the focal neurological symptoms associated with Alzheimer's disease (AD) are due to synaptic loss. Glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging (MRI) is a candidate method to assess synaptic dysfunction. We assessed chronological changes in GluCEST in a 5xFAD mouse model of AD, comparing Glucest effects and regional cerebral blood flow (CBF). GluCEST effects and CBF in 5xFAD mice aged 1-15 months and their littermates (WT) were measured. Neurite orientation dispersion and density imaging (NODDI) MRI reflecting dendritic/axonal density was also measured and compared with GluCEST in 7-month-old mice. While regional CBF's decrease began at 7 months, GluCEST-reduction effects preceded hypoperfusion of the temporal cortex and hippocampus. While longitudinal 5xFAD mouse measurements revealed a correlation between the regional GluCEST effects and CBF, a generalized linear mixed model revealed statistically different correlations in cortical and basal brain regions. Further, NODDI-derived neurite density correlated with GluCEST effects in the parietal cortex, but not in the hippocampus, thereby revealing regional differences in pathophysiological mechanisms. Finally, GluCEST's effects correlated with regional synaptophysin. These results demonstrate that GluCEST can reflect subtle synaptic changes and may be a potential imaging method for AD diagnosis as well as serve as a biomarker of AD progression., Competing Interests: The authors declare that there are no conflicts of interest regarding the publication of this paper., (Copyright © 2020 Hironaka Igarashi et al.)

A 56-year-old man noted sudden onset of headache, fever, right pupil-spared oculomotor nerve palsy and consciousness disturbance. Swelling of pituitary with T 1 high intensity on brain MRI suggested the diagnosis of pituitary apoplexy. Considering significant decrease of pituitary anterior lobe hormone and central diabetes insipidus, high dose of hydrocortisone was administered. Eight days after onset, consciousness level and headache improved. On day 30, brain MRI revealed the reduction of mass size, and on day 46, photophobia and double vision disappeared. Following the rapid response to steroid and disappearance of pituitary lesion, pituitary apoplexy was probably caused by panhypophisitis. Thin-slice brain MRI confirmed the compression of oculomotor nerve at inlet zone of cavernous sinus, suggesting the mechanism of oculomotor palsy was perfusion impairment of feeding artery.

Background and Purpose: Presence of an intimal flap is a critical imaging finding in diagnosing intracranial artery dissection (ICAD). Recent reports showed that high-resolution magnetic resonance imaging (MRI) was better at identifying intimal flaps as compared with routine MRI techniques used in clinical settings. However, no current standardized sequence for high-resolution MRI without gadolinium enhancement produces images of satisfactory quality with clinically tolerable scanning times. This study evaluated a nonenhanced high-resolution fast spin echo (HR-FSE) MRI sequence for visualizing intimal flaps in patients with ICAD., Subjects and Methods: Three patients with ICAD underwent plain MRI examination using a 2-dimensional T2-weighted FSE imaging sequence optimized for our 3T system (in-plane pixel size, .23 mm × .23 mm; slice thickness 3 mm with no interslice gap), as well as scanning with conventional modalities, including CT angiography, magnetic resonance angiography, and digital subtraction angiography. We assessed whether these imaging methods could visualize an intimal flap and/or double lumen sign in the participants and compared the results between HR-FSE and the other modalities., Results: HR-FSE images clearly showed intimal flaps and double lumen signs in all 3 patients, whereas the conventional modalities identified a double lumen sign in only 2 of the 3 patients., Conclusions: The present method of optimized HR-FSE imaging with a 3T system improved visualization of intimal flaps and should thus be considered for assessing patients with suspected ICAD that cannot be definitively diagnosed by conventional imaging modalities., (Copyright © 2016 by the American Society of Neuroimaging.)

Background: Development of molecular MR imaging (MRI) similar to PET imaging using contrast agents such as gadolinium as probe have been inherently hampered by incompatibility between potential probe (charged molecules) and membrane permeability. Nevertheless, considering the inherent spatial resolution limit for PET of 700μ, the superior microscopic resolution of MRI of 4 μ presents a strong incentive for research into ligand-based molecular MRI., Methods: (17) O exhibits JJ vicinal coupling with a covalently bound proton in a hydroxyl group. This (17) O coupled proton can be ionized in water solution and interexchange with other water protons. This property can be utilized as "probe" in T2-weighted imaging and developed into ligand-based molecular MRI. We examined β-amyloid distribution in human APP overexpressed transgenic mice in vivo following injection of (17) O labeled Pittsburg compound B ((17) O-PiB)., Results: JJVCPE imaging successfully imaged (17) O-PiB, unequivocally establishing that (17) O JJVCPE imaging can be developed into PET-like molecular MRI in clinical medicine., Conclusions: The study represents the first successful ligand-based molecular MRI in vivo. This is also the first in vivo amyloid imaging using MRI. High-resolution molecular MRI with high specificity under clinical settings, such as in vivo microscopic imaging of senile plaque, is a foreseeable aim., (Copyright © 2014 The Authors. Journal of Neuroimaging published by the American Society of Neuroimaging.)

Objectives: Intra-arterial transplantation of bone marrow mononuclear cells (BMMCs) effectively improves neuronal function and limits the infarct size. We monitored the fate of BMMCs labeled with super paramagnetic iron oxide (SPIO) until 7 days after the transplantation using high-field magnetic resonance imaging (MRI)., Methods: Male Sprague-Dawley rats were subjected to 90-minute focal ischemia using the intraluminal suture technique followed by transplantation of 1 × 10(7) BMMCs or vehicle only via the ipsilateral carotid artery immediately after reperfusion. Autologous BMMCs were labeled with SPIO by electroporation prior to ischemia. MRI studies were performed at 1 hour, 24 hours, 3 days, and 7 days after reperfusion on each rat. The total infarct volume and the volume of negative dots were measured on T2-weighted images and T2*-weighted images, respectively., Results: One hour after BMMC transplantation, we confirmed wide spread distribution of BMMCs in the ischemic hemisphere as a negative dot. The volume of negative dot normalized by hemispheric volume decreased rapidly and was seldom seen at the seventh day after transplantation. The infarct volume was significantly smaller in the transplanted group than the vehicle group at 24 hours and 7 days after reperfusion., Discussion: The present study established In vivo monitoring of intra-arterial transplanted SPIO-labeled BMMCs immediately after reperfusion using MRI of a rat transient focal ischemia model. The accumulation of BMMCs in ischemic lesion at the acute stage of ischemia can be part of the conditions to limit the infarct size.

Background: Susceptibility-weighted imaging (SWI) microscopy on a 7.0T system demonstrated the corticomedullary junction (CMJ) to be a high-susceptibility region (HSR) in young normal subjects, suggesting that functional alteration of cortical microcirculation could be assessed with this imaging method., Methods: Focused microscopic studies were performed on the parietal association cortex in 74 normal volunteers (ages 20-79 years; 35 female, 39 male) using a SWI algorithm on a system constructed based on General Electric Signa LX (Waukesha, WI, USA), equipped with a 900-mm clear bore superconducting magnet operating at 7.0T., Results: There was a clear-cut reduction in the thickness of the normal-appearing cortex (cortex, R2 = .5290, P < .001) and expansion of CMJ-HSR (R(2) = .6919, P < .001). The sum of cortex thickness and CMJ-HSR thickness was essentially constant, suggesting that the observed expansion of CMR-HSR with aging likely occurred within the cortical mantle., Conclusion: CMJ-HSR expands significantly as a function of aging. Since CMJ-HSR represents a functionally distinct area with relatively slow venous flow, the observed expansion is believed to reflect alteration in cerebral microcirculation with increased age, providing another clue for pathogenesis of Alzheimer's disease., (Copyright © 2011 by the American Society of Neuroimaging.)

Purpose: To clarify whether there are differences in MRI findings between pancreatic lymphomas and autoimmune pancreatitis (AIP)., Materials and Methods: MRI of 8 patients with pancreatic lymphomas and 21 patients with AIP were retrospectively reviewed. For multifocal pancreatic lymphomas (n=2) and AIP (n=4), the largest 2 lesions were evaluated. Ten pancreatic lymphomas and 25 AIP were compared on three bases: the signal intensity on T2-weighted images, internal homogeneity, and presence or absence of capsule-like rim. In 8 lymphomas and 19 AIP, the enhancement pattern on dynamic MRI was compared, as well., Results: On T2-weighted images, pancreatic lymphomas comprised 5, 5 and 4 lesions with low (iso), slightly high, and moderately high intensity, respectively, while the numbers for AIP were 14, 10, and 1 (P<0.01). Nine of 10 (90%) lymphomas appeared homogenous, and 11 of 25 (44%) AIP were homogenous (P<0.05). A capsule-like rim was present in 9 of 25 (36%) AIP, but was not seen in lymphomas (P<0.05). On dynamic MRI, 18 of 19 (94.7%) AIP showed persistent (n=5) or delayed enhancement (n=13), and 6 of 8 (75%) lymphomas showed low intensity without delayed enhancement (P<0.001)., Conclusion: MRI findings for pancreatic lymphomas and AIP were significantly different, which may be helpful for the differential diagnosis of these two diseases., (Copyright (c) 2009 Elsevier Ireland Ltd. All rights reserved.)

Background: Microscopic application of magnetic resonance imaging (MRI) has entered the era of clinical application. One of the most important targets is the visualization of pathological findings such as senile plaques (SP), in vivo, in patients with Alzheimer's disease (AD). Such an application provides not only the most accurate diagnostic tool for clinicians but also a solid basis for scientists for developing effective treatment and preventive strategies for AD., Methods: Focused microscopic studies were performed on parietal association cortex at the level of the centrum semiovale identified on conventional axial slices using a system constructed based on General Electric Signa LX (Waukesha, WI) equipped with a 900-mm clear bore superconducting magnet operating at 7.0 T in 10 patients (67-83-year old, five males, five females) who fulfilled the NINCD and the SADRDA criteria for probable AD, 10 age-matched controls (71-85-year old, five males, five females), and 20 young adults (22-35-year old, 10 males, 10 females) using a susceptibility weighted imaging (SWI) algorithm., Results: SWI microscopy consistently provided images with SP-like pathology extending within the entire parietal cortex in all cases of AD and 2 out of 10 age-matched volunteers., Conclusions: Although the precise mechanisms leading to the higher susceptibility rendering SP-like pathology observable within the cortical mantle are not totally understood, the study unambiguously demonstrated that MR microscopy is capable of directly visualizing cortical pathology in AD patients in vivo.

Background: The ingredients of substances implanted for breast augmentation sometimes remain unknown due to lack of information from patients. Significant clinical problems sometimes necessitate removal and reconstruction. Thus, preoperative diagnostic imaging to identify the ingredients of implants may improve the treatment decision-making process. In this report, we created a clinical imaging index., Purpose: Here, we summarize computed tomography (CT) and magnetic resonance imaging (MRI) imaging of implant materials to predict the ingredients of implant substances preoperatively., Methods: A total of 104 patients with late complications after receiving breast augmentations between 1971 and 2002 were examined using CT and MRI. In addition, further examinations were conducted, including postoperative chemical analysis using Nuclear magnetic resonance (NMR) spectroscopy and MRI imaging of various implanted substances using an experimental magnetic resonance system., Results: We identified the ingredients of implant materials used for breast augmentation by imaging diagnostics as follows: silicone: radiopaque-low/high (CT-MRI T1/T2); hydrogel: radiolucent-low approximately iso/high; hydrocarbon: radiolucent-high approximately iso/low approximately iso; saline: radiolucent-low/high., Conclusion: We have identified by imaging diagnosis the ingredients of implant materials.

Recent advances in MRI technology and the development of effective neuroprotective agents has improved the outcome of stroke. In order to salvage tissue after an ischemic insult it is important to differentiate the core and penumbra area of the ischemic lesion. The penumbra surrounds the ischemic core, damage in this area is reversible if effective neuroprotective agents are given and reperfusion occurs. In this symposium detection of penumbra in an ischemic lesion using diffusion weighted imaging (DWI) and perfusion imaging (PI), diffusion-perfusion mismatch, and indications for thrombolytic therapy are discussed. If a hypoperfusion area is revealed with PI without a corresponding lesion indicated with DWI or when the DWI lesion is less than one third of the PI lesion, combined thrombolytic and neuroprotective therapies are recommended. In contrast, when both PI and DWI show an identical lesion, only neuroprotective therapy is advised. Additionally, newly developed neuroprotective agents, especially the combined effect of rt-PA and the immunosuppressant, FK506, on an embolic infarct model are discussed.

We performed experimental and clinical MR studies to determine the optimal imaging conditions for the uterine three-layer structure on fast spin-echo T2-weighted imaging. In the experimental study, we used our original phantom. Imaging studies were carried out with different TRs, TEs, and ETLs, and the contrast-to-noise ratio (CNR) was evaluated. TR was the most important factor for contrast in both the phantom and clinical studies. The longer TR was, the better the contrast became. In the clinical study, TRs of 5500-6000 msec provided clear visualization of the uterine three-layer structure. Longer TRs would be useful for the detection of disease, differential diagnosis, and grading in patients with uterine diseases.

The purpose of this study was to determine whether regional differences in metabolites can be seen chronologically in permanent focal cerebral ischemia using 1H magnetic resonance spectroscopic imaging (MRSI), and whether these changes reflect pathological outcome. Regional variation in metabolites after permanent focal ischemia were investigated longitudinally in rats using 1H MRSI for a total of 7 days and then compared to histopathological findings. Four hours after the induction of ischemia, N-acetyl-L-aspartate (NAA) levels in the lateral caudo-putamen and the somatosensory cortex, core ischemic regions, decreased 22 and 40%, respectively. This reduction in NAA was coupled with a marked rise in lactate. In the medial caudo-putamen, the ischemic rim, however, NAA was preserved in spite of a marked increase in lactate. By 24 h post ischemia, the levels of NAA in medial caudo-putamen (ischemic rim in caudate) also decreased significantly. However NAA in cingulated cortex (ischemic rim in cortex) decreased more gradually between 24 and 48 h. This regional difference can reflect the severity of metabolic derangement in the acute stage. After 96 h following ischemia, the levels of all metabolites detected by 1H MRSI had decreased and the levels of NAA decline reflected the severity of histopathological damage. In conclusion, the regional metabolic differences could be assessed by 1H MRSI chronologically, and the depth of NAA decline reflected histopathological changes in the chronic stage.

Gd-DTPA has a T1 shortening effect that enhances the contrast in MRI and is widely used for the clinical evaluation of CNS diseases, though it is not suitable for the detection of cerebral ischemic regions during the superacute stage. Superparamagnetic iron oxide particles have a T2 shortening effect on relaxation time, reducing signal intensity on T2-weighted MRI in normal cerebral tissue. From this perspective we tested the feasibility of detecting ischemic lesions during the superacute stage using superparamagnetic iron oxide particles-enhanced MRI. Male Sprague-Dawley rats were anesthetized using pentobarbital and the left middle cerebral artery was permanently occluded (lt.-PMCAO) using a modified version of the Koizumi method. After lt.-PMCAO, 100 mumoles Fe/kg, 1 ml/kg magnetite, superparamagnetic iron oxide particles, (magnetite-injected group, n = 9) or physiological saline (vehicle-injected group, n = 9) was injected into the femoral vein. T2-weighted MR images were performed at designated time points immediately after injection of magnetite or vehicle on a 6.34 T MR unit. Additionally, in separate animals coronal sections of the brain were stained with 4% 2, 3, 5 triphenyl-tetrazolium-chloride (TTC) to confirm the infarct region. In the magnetite-injected group, a high signal area at the region of lt.-MCA was visible within-20 to 30 min following lt.-PMCAO, whereas in the vehicle-injected group no high signal ischemic area could be confirmed until 3 h after lt.-PMCAO. Infarction was noticed in the TTC staining 3 h following lt.-PMCAO. In this study magnetite injection allowed the detection of ischemia in the occluded MCA area on T2-weighted MRI during the superacute stage. These results suggest that ischemia during the superacute stage can be evaluated using magnetite enhanced MRI.

Purpose: To investigate changes in both water diffusion coefficients and diffusion anisotropy in white matter of non-demented patients with leuko-araiosis using diffusion-weighted MRI., Methods: Diffusion mapping was performed on 8 non-demented patients with leuko-araiosis, 6 patients with chronic cerebral infarction and 6 healthy volunteers, using a spin-echo sequence with motion probing gradient applied sequentially at two gradient strength settings in three orthogonal directions. The apparent diffusion coefficients (ADC) were calculated from 4 regions of interest located within the frontal and parietal subcortical white matter. The index of diffusion anisotropy (IDA) was calculated from the ADC in three orthogonal directions. (IDA = ADCmax-min/ADCmean x 100)., Results: Significantly larger ADC were found within the frontal and parietal subcortical white matter in the non-demented patients with leuko-araiosis (mean = 1.51 +/- 0.36 x 10(-3) mm2/s) and the were also significantly larger in patients with cerebral infarction (mean = 2.12 +/- 0.46 x 10(-3) mm2/s) than in the control group (mean = 1.01 +/- 0.33 x 10(-3) mm2/s). But no significant differences were found in the IDA between the non-demented patients with leuko-araiosis (mean = 43.1 +/- 29.2) and the control group (mean = 46.5 +/- 32.5)., Conclusion: An increase in extracellular space caused by the loss of axonal fibers and myelin is probably the cause of the higher ADC in periventricular hyperintensity lesions. However, the remaining nerve fibers maintain the anisotropy in the lesions in non-demented patients with leuko-araiosis.

Thrombolytic therapy during the hyperacute stage is important for salvaging dying cerebral tissue. To date, however, accurate non-invasive assessment of an ischemic lesion during the hyperacute stage has not been possible. Perfusion MRI may be the key to the quick diagnosis of ischemic lesions. To assess the feasibility of dynamic contrast enhanced perfusion MRI, echo planar imaging was performed in 10 patients with ischemic stroke. The relative cerebral blood volume (rCBV), mean transit time (MTT), and relative cerebral blood flow(rCBF) were measured based on moment analysis and the gamma variate method. These measurements, however, are not suitable for the detection of cerebral ischemia during the hyperacute stage. Therefore, we additionally studied the changes in a concentration curve (time-delta R* curve) of Gd-DTPA, injected into the median vein of the forearm. From the curve the SUM (delta R*) time to peak and the delta R* peak, which may be calculated quickly, were determined and were compared to rCBV, MTT, and rCBF, respectively. The rCBV and the rCBF in the ischemic regions were less than those in the contralateral healthy regions (p < 0.05), and the MTT in the ischemic regions was longer than that in the contralateral healthy regions (p < 0.05). Additionally, SUM (delta R*) and the delta R* peak in the ischemic regions were less, and the time to peak in the ischemic regions was longer than the value in the contralateral healthy regions (p < 0.05), correlating well to the rCBV, rCBF, and MTT measurements. Also, images of these parameters, depicting the ischemic lesion earlier than conventional T2 weighted images, can be easily made by using an MRI console. These results suggest that the SUM (delta R*), time to peak and the delta R* peak images calculated with dynamic contrast enhanced perfusion MRI may be one of the best techniques for the detection of cerebral ischemic lesions during the hyperacute stage.

The superacute stage of focal ischemia can be visualized using T2-weighted MRI following the injection of superparamagnetic iron oxide particles (magnetite). In this study we evaluated the optimal time point, i.e. the time producing the strongest signal, for the injection of magnetite using T2-weighted MRI following left parmanent middle cerebral artery occlusion (lt.-PMCAO). Male Sprague-Dawley rats were anesthetized and the left middle cerebral artery (lt.-MCA) was permanently occluded. Magnetite was then injected into the femoral vein after 20 to 30 min of lt.-PMCAO. T2-weighted MR images were taken immediately, and 15 and 30 min after magnetite injection. A high signal area at the region of the lt.-MCA was clearly seen on the T2-weighted MRI immediately after magnetite injection. However, it became less clear after 15 min, and by 30 min could not be distinguished. These results suggest that magnetite should be injected immediately prior to T2-weighted MR imaging during the superacute stage of focal ischemia.

Saturation transfer contrast (STC) techniques have been employed to decrease the signal intensity of observed water by saturating a broad proton component. The STC pulse, generally spatially nonselective, reduces the signal of brain background tissues as well as inflowing blood in 3D time-of-flight (TOF) angiography. We present a novel technique, a slice-selective off-resonance sinc pulse (SORS), which is employed to enhance inflowing blood and to suppress the signal of stationary background tissues. The STC effects of the SORS and other spatially nonselective methods influencing inflowing blood is discussed in detail. Angiograms using the SORS method are also presented to demonstrate improved vessel conspicuity. In addition, the SORS method is applicable to imagers with a whole-body RF transmitter system.

To clarify the mechanism of appearance of low intensity band seen around the abdominal organ, we performed phantom study. The resected intestine, which filled with water and fixed in the salad oil, was obtained by spoiled GRASS MR imaging with variable TEs and fixed TR. On in phase image, low intensity band was seen in low frequency side of frequency encoding direction of surface of the intestine, and high intensity band in high frequency side. On out of phase image, low intensity band is seen all around the intestine. Our phantom study verified that the appearance of low intensity band on out of phase gradient echo image is due to both the misregistration and signal void caused by chemical shift artifact.

Magnetic resonance imaging (MRI) was studied in 91 patients with migraine and in 98 controls. Risk factors known to cause MRI lesions were carefully examined. In 36 patients with migraine (39.6%), small foci of high intensity on T2-weighted and proton-density-weighted images were seen in the white matter. Of patients with migraine who were less than 40 years old and without any risk factor, 29.4% showed lesions on MRI; this was significantly higher than the 11.2% for the group of age-matched controls (n = 98). The lesions were distributed predominantly in the centrum semiovale and frontal white matter in young patients, but extended to the deeper white matter at the level of basal ganglia in the older age group. The side of the MRI lesions did not always correspond to the side of usual aura or headache. Migraine-related variables such as type of migraine, frequency, duration or intensity of headache or consumption of ergotamine showed no significant correlation with the incidence of MRI abnormalities. Our data indicated that migraine may be associated with early pathologic changes in the brain.

Two-dimensional colour Doppler echocardiography was performed on a 1-month-old male infant with criss-cross heart, double outlet right ventricle, ventricular septum defect and pulmonary stenosis. Complex structural abnormalities were suspected after two-dimensional echocardiography (2-D echo) and confirmed by colour Doppler and magnetic resonance imaging (MRI). We stress that the blood streams in the ventricular inflow tracts revealed by colour Doppler and the spatial relationships of the cardiac segments disclosed by MRI are essential to make an accurate non-invasive diagnosis of this complex malformation.

This paper describes topology optimization of electromagnetic systems using the multigrid method. The topology optimization employs uniform rectangular finite elements, in which the multigrid method works effectively as a fast linear solver. Moreover, the present method uses a new optimization algorithm, based on the artificial immune systems paradigm, in which the multilevel search is carried out. [ABSTRACT FROM AUTHOR]

The aim of this study is to report a possible implication of augmented vasogenic leakage in the mechanism of prolonged aura in sporadic hemiplegic migraine. A 35-year-old woman with sporadic hemiplegic migraine presented with headache followed by right arm weakness, right visual field defect, aphasia and confusion that persisted for 1 week. During the acute stage, focal hyperaemia was seen in the left cerebral hemisphere corresponding to persistent aura symptoms. Augmented vasogenic leakage was demonstrated on delayed enhanced fluid-attenuated inversion recovery image. Magnetic resonance angiography showed dilation of the left middle cerebral artery. During the convalescent stage, such abnormal findings were not seen. Based on these results, we speculate that augmented vasogenic leakage from the leptomeningeal vessels, probably associated with activation of the trigeminovascular system, may delay the recovery of hemiplegic migraine aura. [ABSTRACT FROM AUTHOR]