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PURPOSE: To compare reliability and elucidate clinical application of magnetization-prepared rapid gradient-echo (MPRAGE) with 9-fold acceleration by using wave-controlled aliasing in parallel imaging (Wave-CAIPI 3 × 3) in comparison to conventional MPRAGE accelerated by using generalized autocalibrating partially parallel acquisition (GRAPPA) 2 × 1. METHODS: A total of 26 healthy volunteers and 33 patients were included in this study. Subjects were scanned with two MPRAGEs, GRAPPA 2 × 1 and Wave-CAIPI 3 × 3 acquired in 5 min 21 s and 1 min 42 s, respectively, on a 3T MR scanner. Healthy volunteers underwent additional two MPRAGEs (CAIPI 3 × 3 and GRAPPA 3 × 3). The image quality of the four MPRAGEs was visually evaluated with a 5-point scale in healthy volunteers, and the SNR of four MPRAGEs was also calculated by measuring the phantom 10 times with each MPRAGE. Based on the results of the visual evaluation, voxel-based morphometry (VBM) analyses, including subfield analysis, were performed only for GRAPPA 2 × 1 and Wave-CAIPI 3 × 3. Correlation of segmentation results between GRAPPA 2 × 1 and Wave-CAIPI 3 × 3 was assessed. RESULTS: In visual evaluations, scores for MPRAGE GRAPPA 2 × 1 (mean rank: 4.00) were significantly better than those for Wave-CAIPI 3 × 3 (mean rank: 3.00), CAIPI 3 × 3 (mean rank: 1.83), and GRAPPA 3 × 3 (mean rank: 1.17), and scores for Wave-CAIPI 3×3 were significantly better than those for CAIPI 3 × 3 and GRAPPA 3 × 3. Image noise was evident at the center for additional MPRAGE CAIPI 3 × 3 and GRAPPA 3 × 3. The correlation of segmentation results between GRAPPA 2 × 1 and Wave-CAIPI 3 × 3 was higher than 0.85 in all VOIs except globus pallidus. Subfield analysis of hippocampus also showed a high correlation between GRAPPA 2 × 1 and Wave-CAIPI 3 × 3. CONCLUSION: MPRAGE Wave-CAIPI 3 × 3 shows relatively better contrast, despite of its short scan time of 1 min 42 s. The volumes derived from automated segmentation of MPRAGE Wave-CAIPI are considered to be reliable measures.

Purpose Diffusion-weighted MRI (DWI) is an essential sequence for evaluating pediatric patients with moyamoya disease (MMD); however, acoustic noise associated with DWI may lead to motion artifact. Compared with conventional DWI (cDWI), quiet DWI (qDWI) is considered less noisy and able to keep children more relaxed and stable. This study aimed to evaluate the suitability of qDWI compared with cDWI for pediatric patients with MMD. Methods In this observational study, MR examinations of the brain were performed either with or without sedation in pediatric patients with MMD between September 2017 and August 2018. Three neuroradiologists independently evaluated the images for artifacts and restricted diffusion in the brain. The differences between qDWI and cDWI were compared statistically using a chi-square test. Results One-hundred and six MR scans of 56 patients with MMD (38 scans of 15 sedated patients: 6 boys and 9 girls; mean age, 5.2 years; range, 1-9 years; and 68 scans of 42 unsedated patients: 19 boys and 23 girls; mean age, 10.7 years; range, 7-16 years) were evaluated. MR examinations were performed either with or without sedation (except in one patient). In sedated patients, no artifact other than susceptibility was observed on qDWI, whereas four artifacts were observed on cDWI (P = .04). One patient awoke from sedation during cDWI scanning, while no patient awoke from sedation during qDWI acquisition. For unsedated patients, three scans showed artifacts on qDWI, whereas two scans showed artifacts on cDWI (P = .65). Regarding restricted diffusion, qDWI revealed three cases, while two cases were found on cDWI (P = .66). Conclusion qDWI induced fewer artifacts compared with cDWI in sedated patients, and similar frequencies of artifacts were induced by qDWI and by cDWI in unsedated patients. qDWI showed restricted diffusion comparable to cDWI.

OBJECTIVE Carotid webs (CWs) have increasingly been recognized as a cause of recurrent ischemic stroke. However, the natural history and clinical course of CWs remain unclear. The authors aimed to clarify the prevalence, imaging features, and optimal treatment of CWs in a Japanese cohort study. METHODS A series of 444 consecutive Japanese patients who had undergone CTA of the head and neck between April 2011 and October 2016 was retrospectively reviewed. CW was diagnosed on CT angiograms as a membrane-like intraluminal filling defect along the posterior wall of the carotid bulb or the origin of the internal carotid artery (ICA) on oblique sagittal images and a corresponding thin septum on axial images. RESULTS Two patients with CWs were identified among 132 patients with suspected stroke. The prevalence of CWs among symptomatic patients with suspected stroke was 1.5%. The prevalence of asymptomatic CWs was 2.2% (7 of 312 cases). The CWs were located in the posterior wall of the carotid bulb in 7 patients and just distal to the ICA origin in 2 patients. There were no apparent differences in the location or lesion length between symptomatic and asymptomatic CWs. Four of the 7 asymptomatic CWs remained asymptomatic for at least 2 years of follow-up. Two patients with symptomatic CWs developed recurrent cerebral infarction and transient ischemic attack despite being on a regimen of oral antiplatelet agents, and carotid endarterectomy was performed as radical treatment. Patients with CWs were younger than controls (median age 55 vs 69 years, p = 0.003) and were less frequently male than controls (33% vs 72%, p = 0.025). CW cases showed significantly fewer common atherosclerosis risk factors than the control group (p < 0.05). CONCLUSIONS Although limited to CTA patients, this study reported on the prevalence and common site of CWs, focusing on symptomatic and asymptomatic Japanese patients. Extensive cross-sectional and prospective observational studies are warranted to elucidate the overall prevalence and natural history of CWs.

PURPOSE: Time-of-flight (TOF)-MR angiography (MRA) is an important imaging sequence for the surveillance and analysis of cerebral arteriovenous shunt (AVS), including arteriovenous malformation (AVM) and arteriovenous fistula (AVF). However, this technique has the disadvantage of a relatively long scan time. The aim of this study was to compare diagnostic accuracy between compressed sensing (CS)-TOF and conventional parallel imaging (PI)-TOF-MRA for detecting and characterizing AVS. METHODS: This study was approved by the institutional review board for human studies. Participants comprised 56 patients who underwent both CS-TOF-MRA and PI-TOF-MRA on a 3-T MR unit with or without cerebral AVS between June 2016 and September 2018. Imaging parameters for both sequences were almost identical, except the acceleration factor of 3× for PI-TOF-MRA and 6.5× for CS-TOF-MRA, and the scan time of 5min 19s for PI-TOF-MRA and 2min 26s for CS-TOF-MRA. Two neuroradiologists assessed the accuracy of AVS detection on each sequence and analyzed AVS angioarchitecture. Concordance between CS-TOF, PI-TOF, and digital subtraction angiography was calculated using unweighted and weighted kappa statistics. RESULTS: Both CS-TOF-MRA and PI-TOF-MRA yielded excellent sensitivity and specificity for detecting intracranial AVS (reviewer 1, 97.3%, 94.7%; reviewer 2, 100%, 100%, respectively). Interrater agreement on the angioarchitectural features of intracranial AVS on CS-MRA and PI-MRA was moderate to good. CONCLUSION: The diagnostic performance of CS-TOF-MRA is comparable to that of PI-TOF-MRA in detecting and classifying AVS with a reduced scan time under 2.5min.

Objectives: The aim of this study was to assess the accuracy, reliability, and cerebral microbleed (CMB) detection performance of 2-minute quantitative susceptibility mapping (QSM) from 3-dimensional echo-planar imaging (3D-EPI). Materials and Methods: Gadolinium phantom study was conducted using 3D-EPI, single–echo time (TE), and multi-TE gradient-recalled echo (GRE) sequences on two 3-T magnetic resonance (MR) scanners to assess the accuracy between measured and theoretical susceptibility values. The institutional review board approved this prospective study, and 40 healthy volunteers were enrolled with written consent between April 2018 and October 2019. Each underwent 3D-EPI, single-TE, and multi-TE GRE sequences consecutively on one 3-T MR scanner, and QSMs were calculated to assess the reliability of 3D-EPI QSM. Intraclass correlation coefficient (ICC), linear regression, and Bland-Altman plots were calculated. Patients with CMB who underwent both 3D-EPI and GRE QSM scans were retrospectively enrolled. Two radiologists evaluated images independently, and Cohen κ coefficients were calculated to compare CMB detection performance. Results: Phantom study showed excellent validity of 3D-EPI QSM on both MR scanners: Skyra, R2 = 0.996, P < 0.001, ICC = 0.997, mean difference, −2 ppb (95% confidence interval [CI], −45 to 40 ppb); Prisma, R2 = 0.992, P < 0.001, ICC = 0.988, mean difference, 15 ppb (95% CI, −67 to 97 ppb). A human study of 40 healthy volunteers (59 ± 13 years, 25 women) showed excellent reliability with 3D-EPI QSM for both single-TE and multi-TE GRE (R2 = 0.981, P < 0.001, ICC = 0.988; R2 = 0.983, P < 0.001, ICC = 0.990, respectively), supported by a Bland-Altman mean difference of 4 ppb (95% CI, −15 to 23 ppb) for single-TE GRE and 3 ppb (95% CI, −15 to 20 ppb) for multi-TE GRE. The CMB detection performance evaluation from 38 patients (51 ± 20 years, 20 women) showed almost perfect agreement between 3D-EPI and GRE QSM for both raters (κ = 0.923 and 0.942, P < 0.001). Conclusions: Faster QSM from 3D-EPI demonstrated excellent accuracy, reliability, and CMB detection performance.

To assess the feasibility of a denoising approach with deep learning-based reconstruction (dDLR) for fast volume simultaneous multi-slice diffusion tensor imaging of the brain, noise reduction effects and the reliability of diffusion metrics were evaluated with 20 patients. Image noise was significantly decreased with dDLR. Although fractional anisotropy (FA) of deep gray matter was overestimated when the number of image acquisitions was one (NAQ1), FA in NAQ1 with dDLR became closer to that in NAQ5.

Background Neuromelanin‐sensitive magnetic resonance imaging techniques have been developed but currently require relatively long scan times. The aim of this study was to assess the ability of black‐blood delay alternating with nutation for tailored excitation‐prepared T1‐weighted variable flip angle turbo spin echo (DANTE T1‐SPACE), which provides relatively high resolution with a short scan time, to visualize neuromelanin in the substantia nigra pars compacta (SNpc). Methods Participants comprised 49 healthy controls and 25 patients with Parkinson's disease (PD). Contrast ratios of SNpc and hyperintense SNpc areas, which show pixels brighter than thresholds, were assessed between DANTE T1‐SPACE and T1‐SPACE in healthy controls. To evaluate the diagnostic ability of DANTE T1‐SPACE, the contrast ratios and hyperintense areas were compared between healthy and PD groups, and receiver operating characteristic analyses were performed. We also compared areas under the curve (AUCs) between DANTE T1‐SPACE and the previously reported gradient echo neuromelanin (GRE‐NM) imaging. Each analysis was performed using original images in native space and images transformed into Montreal Neurological Institute space. Values of P, April Infographic: Neuromelanin‐Sensitive Magnetic Resonance Imaging Using DANTE Pulse

BACKGROUND AND PURPOSE: Collateral vessels in Moyamoya disease represent potential sources of bleeding. To test whether these cortical distributions vary among subtypes, we investigated cortical terminations using both standardized MR imaging and MRA. MATERIALS AND METHODS: Patients with Moyamoya disease who underwent MR imaging with MRA in our institution were enrolled in this study. MRA was spatially normalized to the Montreal Neurological Institute space; then, collateral vessels were measured on MRA and classified into 3 types of anastomosis according to the parent artery: lenticulostriate, thalamic, and choroidal. We also obtained the coordinates of collateral vessel outflow to the cortex. Differences in cortical terminations were compared among the 3 types of anastomosis. RESULTS: We investigated 219 patients with Moyamoya disease, and a total of 190 collateral vessels (lenticulostriate anastomosis, n = 72; thalamic anastomosis, n = 21; choroidal anastomosis, n = 97) in 46 patients met the inclusion criteria. We classified the distribution patterns of collateral anastomosis as follows: lenticulostriate collaterals outflowing anteriorly (P

[Background]: Quantitative susceptibility mapping (QSM) is used to differentiate between calcification and iron deposits. Few studies have examined the relationship between CT attenuation values and magnetic susceptibility in such materials. Purpose: To assess the relationship among metal concentration, CT attenuation values, and magnetic susceptibility in paramagnetic and diamagnetic phantoms, and the relationship between CT attenuation values and susceptibility in brain structures that have paramagnetic or diamagnetic properties. [Materials and Methods]: In this retrospective study, CT and MRI with QSM were performed in gadolinium and calcium phantoms, patients, and healthy volunteers between June 2016 and September 2017. In the phantom study, we evaluated correlations among metal concentration, CT attenuation values, and susceptibility. In the human study, Pearson and Spearman correlations were performed to assess the relationship between CT attenuation values and susceptibility in regions of interest placed in the globus pallidus (GP), putamen, caudate nucleus, substantia nigra, red nucleus, dentate nucleus, choroid plexus, and hemorrhagic and calcified lesions. [Results]: Eighty-four patients (mean age, 64.8 years 6 19.6; 49 women) and 20 healthy volunteers (mean age, 72.0 years 6 7.6; 11 men) were evaluated. In the phantoms, strong linear correlations were identified between gadolinium concentration and CT and MRI QSM values (R2 = 0.95 and 0.99, respectively; P , .001 for both) and between calcium concentration and CT and MRI QSM values (R2 = 0.89 [P = .005] and R2 = 0.98 [P , .001], respectively). In human studies, positive correlations between CT attenuation values and susceptibility were observed in the GP (R2 = 0.52, P , .001) and in hemorrhagic lesions (R2 = 0.38, P , .001), and negative correlations were found in the choroid plexus (R2 = 0.53, P , .001) and in calcified lesions (R2 = 0.38, P = .009). [Conclusion]: CT attenuation values showed a positive correlation with susceptibility in the globus pallidus and hemorrhagic lesions and negative correlation in the choroid plexus and calcified lesions.

BACKGROUND Time-resolved angiography with interleaved stochastic trajectories (TWIST) is a keyhole imaging with frequent sampling of central k-space data and view-sharing for the peripheral k-space of dynamic phases. IT-TWIST is a technique to reconstruct images with a smaller temporal footprint using the same raw data obtained with TWIST by iterative reconstruction. PURPOSE To compare image quality between TWIST and IT-TWIST in 3D pituitary DCE-MRI. STUDY TYPE Retrospective observation study. POPULATION Fifty-one patients (23 men, 28 women) who underwent 3D pituitary DCE-MRI using TWIST between July 2016 and April 2017. FIELD STRENGTH/SEQUENCE 3T/TWIST and IT-TWIST. ASSESSMENT Visual evaluation was conducted for image quality of delineation of the pituitary stalk and posterior lobe during the early arterial phase, cerebral white matter near the sella turcica, and the mass lesion. Bolus sharpness of the pituitary stalk, posterior lobe, and bilateral cavernous sinus was evaluated on the enhancement slope map calculated from TWIST and IT-TWIST. Temporal stability of intensity of the nonenhanced area was evaluated on temporal standard deviation (SD) maps calculated from TWIST and IT-TWIST. STATISTICAL TESTS Paired t-test or Wilcoxon rank-sum test was used to test the differences between TWIST and IT-TWIST in both visual evaluation and region of interest evaluation. RESULTS Scores of visual evaluations for IT-TWIST were significantly better than those for TWIST (P

[Purpose] Flexible positron emission tomography (fxPET) employing a non-local means reconstruction algorithm was designed to fit existing magnetic resonance imaging (MRI) systems. We aimed to compare the qualitative and quantitative performance of fxPET among fxPET with MR-based attenuation correction (MRAC), fxPET with CT-based attenuation correction (CTAC) using CT as a part of WB PET/CT, and whole-body (WB) PET/CT. [Procedures] Sixteen patients with suspected head and neck cancer underwent 2-deoxy-2-[18F]fluoro-D-glucose WB PET/CT scans, followed by fxPET and 3 T MRI scans. Phantom data were compared among the three datasets. For registration accuracy, we measured the distance between the center of the tumor determined by fxPET and that in MRI. We compared image quality, detection rates, and quantitative values including maximal standardized uptake value (SUVmax), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and tumor-to-muscle ratio (TMR) among the three datasets. [Results] The phantom data in fxPET, except the percent contrast recoveries of 17-mm and 22-mm hot spheres, were inferior to those in WB PET/CT. The mean registration accuracy was 4.4 mm between fxPET using MRAC and MRI. The image quality was comparable between two fxPET datasets, but significantly inferior to WB PET/CT (p

[Purpose]To evaluate the clinical feasibility of a newly developed mobile PET system with MR-compatibility (flexible PET; fxPET), compared with conventional PET (cPET)/CT for brain imaging.[Methods]Twenty-one patients underwent cPET/CT with subsequent fxPET/MRI using 18F-FDG. As qualitative evaluation, we visually rated image quality of MR and PET images using a four-point scoring system. We evaluated overall image quality for MR, while we evaluated overall image quality, sharpness and lesion contrast. As quantitative evaluation, we compared registration accuracy between two modalities [(fxPET and MRI) and (cPET and CT)] measuring spatial coordinates. We also examined the accuracy of regional 18F-FDG uptake.[Results]All acquired images were of diagnostic quality and the number of detected lesions did not differ significantly between fxPET/MR and cPET/CT. Mean misregistration was significantly larger with fxPET/MRI than with cPET/CT. SUVmax and SUVmean for fxPET and cPET showed high correlations in the lesions (R = 0.84, 0.79; P

[Background]: Hypothalamic–pituitary–thyroid (HPT) maturation has not been extensively evaluated using neonatal MRI, even though both structures are visualized on MRI. [Hypothesis]: That signal intensity and volume of pituitary and thyroid (T) glands on MRI in neonates may be interrelated. [Study Type]: Retrospective. [Subjects]: In all, 102 participants. [Field Strength/Sequence]: 3.0T, T₁‐weighted pointwise encoding time reduction with radial acquisition (PETRA).[ Assessment]: The volume of interest of the anterior pituitary (AP), posterior pituitary (PP), and T on MRI were defined on T₁‐PETRA by two radiologists, and volumes of AP (AP_vol) and thyroid (T_vol) were calculated. Gestational age (GA), chronological age (CA), GA+CA, birth weight (BW), and thyroid function were recorded. Mean and maximum signal intensities of AP, PP, and T were normalized using signals from the pons and spinal cord as follows: signal ratio of anterior pituitary/pons (AP/pons), signal ratio of posterior pituitary/pons (PP/pons), and signal ratio of thyroid/cord (T/cord) T/cord, respectively. [Statistical Tests]: Correlations between signal intensity and volume measures and GA, CA, GA+CA, and BW were assessed using Pearson's correlation coefficient or Spearman's rank correlation coefficient. Thyroid function analysis and Tmean/cord, Tmax/cord, and T_vol were evaluated using the Steel–Dwass test. Results: APmean/pons correlated positively with GA (ρ = 0.62, P < 0.001) and BW (ρ = 0.74, P < 0.001), and negatively with CA (ρ = −0.86, P < 0.001) and GA+CA (ρ = −0.46, P < 0.001). PPmean/pons correlated positively with GA (ρ = 0.49, P < 0.001) and BW (ρ = 0.63, P < 0.001), and negatively with CA (ρ = −0.70, P < 0.001) and GA+CA (r = −0.38, P < 0.001). Tmean/cord correlated positively with GA (ρ = 0.48, P < 0.001) and BW (ρ = 0.55, P < 0.001), and negatively with CA (ρ = −0.59, P < 0.001) and GA+CA (ρ = −0.22, P = 0.03). AP_vol correlated positively with GA (ρ = 0.68, P < 0.001) and BW (ρ = 0.73, P < 0.001), and negatively with CA (ρ = −0.72, P < 0.001). T_vol correlated positively with GA (ρ = 0.50, P < 0.001) and BW (ρ = 0.61, P < 0.001), and negatively with CA (ρ = −0.54, P < 0.001). APmean/pons correlated positively with Tmean/cord (ρ = 0.61, P < 0.001). [Data Conclusion]: Signal and volume of pituitary and thyroid glands correlated positively with GA and BW, and negatively with CA in neonates. [Level of Evidence]: 4 [Technical Efficacy Stage]: 5

The chemical exchange saturation transfer (CEST) effect on an egg white (EW) suspension was investigated for optimization of magnetization transfer (MT) power (B1,rms) and pH dependency with the addition of lactic acid. Applying a higher MT pulse, B1,rms, Z-spectrum shows higher asymmetry and the magnetisation transfer ratio (MTR)asym signal increases to around 1-3.5 ppm, indicating a higher CEST effect. Amide proton transfer (APT) at 3.5 ppm shows a signal elevation in MTRasym with the application of higher B1,rms power and high pH. In addition, the hydroxyl proton signal in MTRasym increases as pH is reduced by lactic acid. In Z-spectrum of B1,rms at 1.0 μT and 2.0 μT, the dependence on CEST effect of amide proton and hydroxyl proton could be observed by using an EW suspension phantom. The CEST MT power was optimized on the EW suspension phantom with pH dependency and further confirmed on volunteers. In addition, APT imaging at 3.5 ppm using B1,rms at 1.0 μT performed on two human brains with different pathophysiological conditions indicated appropriate ATP effect.

Purpose Gadolinium deposition in dentate nucleus (DN) has been reported after serial administration of gadolinium-based contrast agents (GBCAs). Gadolinium complexes have paramagnetic properties; therefore, we evaluated susceptibility changes of gadolinium deposition in DN using quantitative susceptibility mapping (QSM) for patients after serial administration of GBCAs. Materials and Methods In all, 48 patients with brain tumors, who had had serial GBCA administrations (GBCA group), and 48 healthy volunteers without any history of GBCA administrations (non-GBCA group) were enrolled in this study. Susceptibility values in DN on QSM and DN-to-cerebellum signal intensity ratios on unenhanced T1-weighted images (T1 ratios) on 3T were analyzed. The relationship between the number of times of GBCA administrations and susceptibility values or T1 ratios were evaluated in the GBCA group. Results Susceptibility values at DN in the GBCA group were 0.107 ± 0.029 ppm, and significantly higher than those of the non-GBCA group (0.079 ± 0.025 ppm) (P < 0.0001). T1 ratios in DN of the GBCA group were 1.059 ± 0.070, and also significantly higher than that of the non-GBCA group (0.993 ± 0.016) (P < 0.0001). Spearman rank correlation coefficients between susceptibility values and the number of times of linear GBCA administration showed a modest significant correlation (ρ = 0.45, P = 0.0015). There was good correlation between T1 ratios and the number of times of linear GBCA administration, as reported previously (ρ = 0.76, P < 0.0001). Conclusion Susceptibility values on QSM in DN of the GBCA group, after serial administration of GBCAs, were significantly higher than those of the non-GBCA group. Evidence Level: 3 J. Magn. Reson. Imaging 2016

The purpose of this study is to clarify the degree of impregnation resulting from treatment of internal waterlogged wood samples using MRI. On a 1.5T MR scanner, T1 and T2 measurements were performed using inversion recovery and spin-echo sequences, respectively. The samples were cut waterlogged pieces of wood treated with various impregnation techniques which were divided into different concentrations of trehalose (C12H22O11) and polyethylene glycol (PEG; HO-(C2H4O)n-H) solutions. Then these samples underwent impregnation treatment every two weeks. From the results, we found that the slope of the T1-concentration curve using linear fitting showed the value of the internal area for PEG to be higher than the external area; internal, -2.73ms/wt% (R2=0.880); external, -1.50ms/wt% (R2=0.887). Furthermore, the slope of the T1-concentration curve using linear fitting showed the values for trehalose to have almost no difference when comparing the internal and the external areas; internal, -2.79ms/wt% (R2=0.759); external, -3.02ms/wt% (R2=0.795). However, the slope of the T2-concentration curve using linear fitting for PEG showed that there was only a slight change between the internal and the external areas; internal, 0.26ms/wt% (R2=0.642); external, 0.18ms/wt% (R2=0.920). The slope of the T2-concentration curve did not show a change in linear relationship between the internal and the external areas; internal, 0.06ms/wt% (R2=0.175); external, -0.14ms/wt% (R2=0.043). In conclusion, using visualization of relaxation time T1, it is possible to obtain more detail information noninvasively concerning the state of impregnation treatment of internal waterlogged wood.

PURPOSE To investigate age-related changes in T1 relaxation time in deep gray matter structures in healthy volunteers using magnetization-prepared 2 rapid acquisition gradient echoes (MP2RAGE). MATERIALS AND METHODS In all, 70 healthy volunteers (aged 20-76, mean age 42.6 years) were scanned at 3T magnetic resonance imaging (MRI). A MP2RAGE sequence was employed to quantify T1 relaxation times. After the spatial normalization of T1 maps with the diffeomorphic anatomical registration using the exponentiated Lie algebra algorithm, voxel-based regression analysis was conducted. In addition, linear and quadratic regression analyses of regions of interest (ROIs) were also performed. RESULTS With aging, voxel-based analysis (VBA) revealed significant T1 value decreases in the ventral-inferior putamen, nucleus accumbens, and amygdala, whereas T1 values significantly increased in the thalamus and white matter as well (P

We report a case of anti-N-methyl-D-aspartate-receptor (anti-NMDAR) encephalitis associated with an immature teratoma developed in a 38-year-old woman. Positron emission tomography (PET) revealed focal intense uptake of F-fluorodeoxyglucose in an area of the brain corresponding to the right medial temporal lobe as well as an intrapelvic tumor. After the PET examination, the patient complained of disorientation and short-term memory loss. The ovarian tumor was resected and diagnosed as an immature teratoma. The cerebrospinal fluid analysis was positive for anti-NMDAR antibody. After surgery, the patient's neurologic symptoms improved. The PET finding of encephalitis associated with an immature teratoma was unexpected.

A 76-year-old woman underwent 123I-FP-CIT brain SPECT due to postural reflex impairment. The transverse slices demonstrated increased uptake in the right middle cerebral artery territory. MR images obtained 2 weeks earlier showed cerebral infarction in the corresponding area. 123I-FP-CIT has high binding affinity for dopamine transporters, especially in the nerve endings of nigrostriatal dopaminergic neurons.

BACKGROUND AND PURPOSE: The location of intracerebral hemorrhage in Moyamoya disease is a prognostic factor for rebleeding and the degree of preventive effects obtainable with bypass surgery. We evaluated whether the bleeding point and responsible vessel were detectable using fusion images of SWI and time-of-flight MRA performed during chronic-phase hemorrhage. MATERIALS AND METHODS: We retrospectively enrolled 42 patients with hemorrhagic Moyamoya disease (48 hemorrhagic events). Fusion images of SWI and MRA were made using workstations, and we defined the bleeding point as the point at which the signal of an abnormally extended artery on MRA overlapped the hypointense area on SWI. Two independent raters identified the bleeding point, and classified the location and responsible vessels. RESULTS: The bleeding point was detectable at a frequency of 79.2% by rater 1. Agreement for the presence of a bleeding point was high (interrater κ = 0.83; 95% CI, 0.65–1; intrarater κ = 0.86; 95% CI, 0.68–1). The frequency of a periventricular location of the bleeding point was 65.8% by rater 1, and agreement on the location was again high (interrater κ = 0.92; 95% CI, 0.82–1; intrarater κ = 0.85; 95% CI, 0.72–0.99). The choroidal artery was the most frequent responsible vessel (57.9% by rater 1), and agreement on the responsible vessel was high (interrater κ = 0.84; 95% CI, 0.69–1; intrarater κ = 0.90; 95% CI, 0.78–1). CONCLUSIONS: Detection of the bleeding point in hemorrhagic Moyamoya disease using SWI and MRA fusion images offers highly reproducible results.

While periventricular anastomosis, a unique abnormal vasculature in moyamoya disease, has been studied in relation to intracranial hemorrhage, no study has addressed its change after bypass surgery. The authors sought to test whether direct bypass surgery could restore normal periventricular vasculature. Patients who had undergone direct bypass surgery for moyamoya disease at a single institution were eligible for the study. Baseline, postoperative, and follow-up magnetic resonance angiography (MRA) scans were scheduled before surgery, after the first surgery, and 3 to 6 months after contralateral second surgery, respectively. Sliding-thin-slab maximum-intensity-projection coronal MRA images of periventricular anastomoses were scored according to the three subtypes (lenticulostriate, thalamic, and choroidal anastomosis). Baseline and postoperative MRA images were compared to obtain a matched comparison of score changes in the surgical and nonsurgical hemispheres within individuals (intra-individual comparison). Of 110 patients, 42 were identified for intra-individual comparisons. The periventricular anastomosis score decreased significantly in the surgical hemispheres (median, 2 versus 1; p

Purpose This study aims to investigate difference between magnetization-prepared rapid gradient-echo imaging (MPRAGE) and spin-echo (SE) imaging for evaluating glioma on pre-contrast-enhanced (CE) and post-CE T1-weighted images at 3 T. Materials and methods We retrospectively assessed pre-CE and post-CE T1-weighted images for tumor contrast in 64 consecutive glioma patients. Results In the nonenhancing tumors, the contrast was significantly clearer in MPRAGE than SE. In the enhancing tumors, post-CE contrast ratio was significantly higher in SE than MPRAGE, but when subtraction images are evaluated, the difference got smaller. Conclusion MPRAGE can be a good substitute of SE for T1-weighted imaging of glioma.

Background The thickness and signal intensity (SI) of normal uterine endometrium on T2-weighted (T2W) imaging changes depend on the menstrual cycle phase. Cases of normal endometrium that appear similar to endometrial lesions sometimes occur, and may result in misdiagnosis. Purpose To investigate normal endometrial appearance in luteal phase (LP) compared to that in follicular phase (FP), and to differentiate these appearances with those of endometrial lesions. Material and Methods Thirty-two normal volunteers prospectively underwent magnetic resonance (MR) examinations during LP and FP. Patients with pathologically confirmed endometrial polyps ( n = 9), hyperplasia ( n = 7), and cancer ( n = 15), who underwent MR examinations, were evaluated for comparison. Endometrial appearance was categorized into the following five types on sagittal T2W imaging and compared between LP, FP, and endometrial lesions: type 1, homogeneous higher SI; type 2, homogeneous iso SI; type 3, a bright midline and a peripheral iso SI layer; type 4, a lower/iso SI central line; and type 5, heterogeneous lower/iso SI. Endometrial thickness and SI were measured and also compared. Results Endometrial lesions were more frequently categorized as type 5 than normal endometrium ( P Conclusion Differentiation between normal endometrium in LP and endometrial lesions may be difficult based on thickness alone. Heterogeneous low SI may help to differentiate normal endometrium from endometrial lesions. Performing MR imaging during FP may also help due to higher SI of normal endometrium.

The aim of this study was to evaluate the clinical feasibility of accelerated time-of-flight (TOF) magnetic resonance angiography with sparse undersampling and iterative reconstruction (sparse TOF).The local institutional review board approved the study protocols. Twenty healthy volunteers were recruited (mean age, 31.2 years; age range, 22-52 years; 14 men, 6 women). Both sparse TOF and parallel imaging (PI) TOF were obtained on a 3 T scanner. Acceleration factors were 3, 4, 5, 6, and 8 for sparse TOF (Sp 3×, Sp 4×, Sp 5×, Sp 6×, and Sp 8×, respectively) and 2, 3, 4, and 6 for PI TOF (PI 2×, PI 3×, PI 4×, and PI 6×, respectively). Images were reconstructed on the scanner, and maximum intensity projection images were subjected to visual evaluation, wherein each segment of the major brain arteries was independently evaluated by 2 radiologists on a 4-point scale (1, poor; 2, limited; 3, moderate/good quality for diagnosis; and 4, excellent). As a quantitative evaluation, the apparent contrast-to-background deviation (apparent CBD) was calculated at the level of the basilar artery and the pons.A total number of 1800 segments were subjectively evaluated. There was substantial agreement regarding vessel visualization (κ = 0.759). Sparse TOF received scores above 3 (good for diagnosis) at any acceleration factor up to the third segments of major arteries. The middle and distal segments of PI 4× and PI 6× were graded below 3 (limited or poor diagnostic value). Sp 3×, 4×, 5×, and 6× retained diagnostic information (graded above 3), even at distal segments. The apparent CBD of sparse TOF at any acceleration factor was equivalent to that of PI 2×, whereas the apparent CBD of PI 3×, PI 4×, and PI 6× attenuated with the acceleration factor.Sparse TOF can achieve better image quality relative to PI TOF at higher acceleration factors. The diagnostic quality of distal branches (A2/3, M4, P4) was maintained with Sp 6×, which achieved a shorter acquisition time less than half of PI 2×.

The pathophysiological mechanism of chorea as a presentation of pediatric moyamoya disease remains unknown, although ischemia is suspected as a likely cause. The authors describe two cases of pediatric moyamoya disease, both of which presented with hemichorea in the stable phase after successful bypass surgery. Cerebral blood flow was almost normal in one case and decreased in the basal ganglia and watershed area in the other case due to infarcts occurring before surgery. In both cases, 18F-fluorodeoxyglucose positron emission tomography revealed elevated glucose metabolism in the corresponding side of the striatum, which reverted to normal after recovery from chorea. Magnetic resonance angiography revealed a dilated and extended lenticulostriate artery at the exact site of the hypermetabolic lesion.

To compare visualization of carotid plaques and vessel walls between 3D T1-fast spin echo imaging with conventional SPACE (T1-SPACE) and with a prototype compressed sensing T1-SPACE (CS-T1-SPACE) This retrospective study was approved by the institutional review board. Participants comprised 43 patients (36 males, 7 females; mean age, 71 years) who underwent carotid MRI including T1-SPACE and CS-T1-SPACE. The quality of visualization for carotid plaques and vessel walls was evaluated using a 5-point scale, and signal intensity ratios (SRs) of the carotid plaques were measured and normalized to the adjacent sternomastoid muscle. Scores for the quality of visualization were compared between T1-SPACE and CS-T1-SPACE using the Wilcoxon signed-rank test. Statistical differences between SRs of plaques with T1-SPACE and CS-T1-SPACE were also evaluated using the Wilcoxon signed-rank test, and Spearman’s correlation coefficient was calculated to investigate correlations. Visualization scores were significantly higher for CS-T1-SPACE than for T1-SPACE when evaluating carotid plaques (p = 0.0212) and vessel walls (p

This case report describes the usefulness of delay alternating with nutation for tailored excitation (DANTE)-prepared, contrast-enhanced magnetic resonance imaging (CE-MRI) for detecting the rupture site of an arteriovenous malformation (AVM). A ruptured intranidal aneurysm was confirmed histopathologically. Accurate non-invasive information about the possible rupture site of an AVM is critical for optimal treatment and evaluation. Vessel wall enhancement visualized by DANTE-prepared CE-MRI may be a useful tool for providing information about changes in inflammatory status and vulnerability to further developments.

Introduction: Intimal flap-like protrusion of the carotid artery is referred to as a carotid web (also known as carotid diaphragm and atypical fibromuscular dysplasia) that can cause recurrent ischemic stroke. We retrospectively studied the prevalence, demographics, clinical presentation, and imaging features of all patients in a series with defined carotid webs, and describe the treatment and histopathology of two that were symptomatic. Methods: This retrospective study analyzed data from a series of 505 patients who underwent head and neck computed tomography angiography (CTA) at Kyoto University Hospital between April 2011 and Oct 2016. Reports have indicated that CTA is reliable for detecting carotid webs, which are defined on images of oblique sagittal sections as a thin intraluminal filling defect along the posterior wall of the carotid bulb. Ultrasonic echo and MRI findings were also matched when available. Carotid webs were finally defined by interpretation of CTA images by a radiologist and an experienced neurosurgeon. Results: The prevalence of carotid webs in this series was 1.8% (9 of 505 patients), the mean age was 56 (range, 42 - 67) years, and six patients were women. Two (22.2%) of the nine patients with carotid webs had recurrent stroke and both were treated radically by carotid endarterectomy. The histopathological findings suggested fibromuscular dysplasia accompanied by early atherosclerotic changes. Conclusions: The prevalence of carotid webs was low and they tended to occur more frequently among women in the present series. An optimal management strategy has not yet been devised. However, recurrent ischemic stroke might be caused by turbulent blood flow at the point of recess that leads to the formation of thrombus and emboli. We recommend that such patients undergo radical treatment.

Compressed sensing (CS) reconstructions of under-sampled measurements generate missing data based on assumptions of image sparsity. Non-contrast time-of-flight MR angiography (TOF-MRA) is a good candidate for CS based acceleration, as MRA images feature bright trees of sparse vessels over a well-suppressed anatomical background signal. A short scan time derived from CS is beneficial for patients of moyamoya disease (MMD) because of the frequency of MR scans. The purpose of this study was to investigate the reliability of TOF-MRA with CS in the evaluation of MMD. Twenty-two patients were examined using TOF-MRA with CS (CS-TOF) and parallel imaging (PI-TOF). The acceleration factors were 3 (CS3) and 5 (CS5) for CS-TOF, and 3 (PI3) for PI-TOF. Two neuroradiologists evaluated the MMD grading according to stenosis/occlusion scores using the modified Houkin’s system, and the visibility of moyamoya vessels (MMVs) using a 3-point scale. Concordance was calculated with Cohen’s κ. The numbers of MMVs in the basal ganglia were compared using Bland-Altman analysis and Wilcoxon’s signed-rank tests. MRA scan times were 4:07, 3:53, and 2:42 for PI3, CS3, and CS5, respectively. CS-reconstruction completed within 10 minutes. MMD grading and MMV visibility scales showed excellent correlation (κ > .966). Although the number of MMVs was significantly higher in CS3 than in PI3 (p < .0001) and CS5 (p < .0001), Bland-Altman analysis showed a good agreement between PI3, CS3, and CS5. Compressed sensing can accelerate TOF-MRA with improved visualization of small collaterals in equivalent time (CS3) or equivalent results in a shorter scan time (CS5).

【Background】Transient neurological deficits are relatively common after direct revascularization surgery for moyamoya disease (MMD). Although recent evidence has revealed the clinical features and pathophysiology, preoperative predictors have remained unclear. This study investigated whether the apparent diffusion coefficient (ADC) in normal-appearing white matter (NAWM) on magnetic resonance imaging could offer a predictor of postoperative transient neurological deficits. 【Methods】This study included adult patients with MMD who underwent superficial temporal artery-middle cerebral artery bypass. Preoperative ADCs were measured in NAWM on ipsilateral hemisphere. Single photon emission computed tomography (SPECT) with123I-iodoamphetamine was performed on postoperative days 2-6. Relationships between mean ADC and postoperative transient neurological deficits were assessed. 【Results】Results Twenty of the 26 subjects (76.9%) experienced transient neurological deficits. Focal hyperemia on postoperative SPECT appeared in 11 of the 20 subjects with postoperative transient neurological deficits and 1 of the 6 subjects without (P = .12). Mean ADCs in patients with and without postoperative transient neurological deficits were 748.3 ± 12 mm2/second × 10−6 and 679.7 ± 21.9 mm2/second × 10−6, respectively (P = .0091). 【Conclusions】Preoperative ADC elevation in NAWM may indicate postoperative transient neurological deficits not only in patients with postoperative hyperemia on SPECT, but also in patients with this pathology., Available online 10 July 2015

OBJECT Unstable moyamoya disease, reasonably defined as cases exhibiting either rapid disease progression or repeated ischemic stroke, represents a challenge in the treatment of moyamoya disease. Despite its overall efficacy, direct bypass for such unstable disease remains controversial in terms of safety. This study aims to reveal factors associated with unstable disease and to assess its impact on postoperative silent or symptomatic ischemic lesions. METHODS This retrospective cohort study included both pediatric and adult patients with moyamoya disease who had undergone 140 consecutive direct bypass procedures at Kyoto University Hospital. “Unstable moyamoya disease” was defined as either the rapid progression of a steno-occlusive lesion or repeat ischemic stroke, either occurring within 6 months of surgery. The extent of progression was determined through a comparison of the findings between 2 different MR angiography sessions performed before surgery. The clinical variables of the stable and unstable disease groups were compared, and the association between unstable disease and postoperative diffusion-weighted imaging (DWI)–detected lesion was assessed through univariate and multivariate analyses with generalized estimating equations. RESULTS Of 134 direct bypass procedures performed after patients had undergone at least 2 sessions of MR angiography, 24 (17.9%) were classified as cases of unstable disease. Age younger than 3 years (p = 0.029), underlying disease causing moyamoya syndrome (p = 0.049), and radiographic evidence of infarction (p = 0.030) were identified as factors associated with unstable disease. Postoperative DWI-defined lesions were detected after 13 of 140 procedures (9.3%), although only 4 lesions (2.9%) could be classified as a permanent complication. The incidence of postoperative DWI-detected lesions in the unstable group was notable at 33.3% (8 of 24). Univariate analysis revealed that unstable disease (p < 0.001), underlying disease (p = 0.028), and recent stroke (p = 0.012) were factors associated with DWI-detected lesions. Unstable disease remained statistically significant after adjustment for covariates in both the primary and sensitivity analyses (primary analysis: OR 6.62 [95% CI 1.79–24.5]; sensitivity analysis: OR 5.36 [95% CI 1.47–19.6]). CONCLUSIONS Unstable moyamoya disease, more prevalent in younger patients and those with underlying disease, is a possible risk factor for perioperative ischemic complications. Recognition of unstable moyamoya disease may contribute to an improved surgical result through focused perioperative management based on appropriate surgical risk stratification.

Fragile abnormal collaterals in moyamoya disease, known as “moyamoya vessels,” have rarely been defined. While flow-sensitive black-blood magnetic resonance angiography (FSBB-MRA) is a promising technique for visualizing perforating arteries, as of this writing no other reports exist regarding its application to moyamoya disease. Six adults with moyamoya disease underwent FSBB-MRA. It depicted abnormal collaterals as extended lenticulostriate, thalamic perforating, or choroidal arteries, which were all connected to the medullary or insular artery in the periventricular area and supplied the cortex. This preliminary case series illustrates the potential for FSBB-MRA to reveal abnormal moyamoya vessels, which could be reasonably defined as periventricular collaterals.

Compressed sensing (CS) MRI has just been introduced to research areas as an innovative approach to accelerate MRI. CS is expected to achieve higher k-space undersampling by exploiting the underlying sparsity in an appropriate transform domain. MR angiography (MRA) provides high spatial resolution information on arteries; however, a relatively long acquisition time is necessary to cover a wide volume. Reduction of acquisition time by CS for time-of-flight (TOF) MR angiography (Sparse-TOF) is beneficial in clinical examinations; therefore, the clinical validity of Sparse-TOF needs to be investigated. The aim of this study was to compare the diagnostic capability of TOF MRA between parallel imaging (PI)-TOF with an acceleration factor of 3 (annotated as 3×) and Sparse-TOF (3× and 5×) in patients with cerebral aneurysms. PI-TOF (3×) and Sparse-TOF (3× and 5×) imaging were performed in 20 patients using a 3 T MRI system. Aneurysms in PI-TOF (3×) and Sparse-TOF (3× and 5×) were blindly rated as visible or scarcely visible by neuroradiologists. The neck, height and width of aneurysms were also measured. Twenty-six aneurysms were visualized and rated as visible in PI-TOF (3×) and Sparse-TOF (3× and 5×), with excellent agreement between two raters. No significant differences were found in measured neck, height or width of aneurysms among them. Sparse-TOF (3× and 5×) were acquired and reconstructed within 6 min, and cerebral aneurysms were visible in both of them with equivalent quality to PI-TOF (3×). Sparse-TOF (5×) is a good alternative to PI-TOF (3×) to visualize cerebral aneurysms.

BACKGROUND AND PURPOSE: Amide proton transfer imaging has been successfully applied to brain tumors, however, the relationships between amide proton transfer and other quantitative imaging values have yet to be investigated. The aim was to examine the additive value of amide proton transfer imaging alongside [(18)F] FDG-PET and DWI for preoperative grading of gliomas. MATERIALS AND METHODS: Forty-nine patients with newly diagnosed gliomas were included in this retrospective study. All patients had undergone MR imaging, including DWI and amide proton transfer imaging on 3T scanners, and [(18)F] FDG-PET. Logistic regression analyses were conducted to examine the relationship between each imaging parameter and the presence of high-grade (grade III and/or IV) glioma. These parameters included the tumor-to-normal ratio of FDG uptake, minimum ADC, mean amide proton transfer value, and their combinations. In each model, the overall discriminative power for the detection of high-grade glioma was assessed with receiver operating characteristic curve analysis. Additive information from minimum ADC and mean amide proton transfer was also evaluated by continuous net reclassification improvement. P < .05 was considered significant. RESULTS: Tumor-to-normal ratio, minimum ADC, and mean amide proton transfer demonstrated comparable diagnostic accuracy in differentiating high-grade from low-grade gliomas. When mean amide proton transfer was combined with the tumor-to-normal ratio, the continuous net reclassification improvement was 0.64 (95% CI, 0.036–1.24; P = .04) for diagnosing high-grade glioma and 0.95 (95% CI, 0.39–1.52; P = .001) for diagnosing glioblastoma. When minimum ADC was combined with the tumor-to-normal ratio, the continuous net reclassification improvement was 0.43 (95% CI, −0.17–1.04; P = .16) for diagnosing high-grade glioma, and 1.36 (95% CI, 0.79–1.92; P < .001) for diagnosing glioblastoma. CONCLUSIONS: Addition of amide proton transfer imaging to FDG-PET/CT may improve the ability to differentiate high-grade from low-grade gliomas.

Rationale and Objectives To optimize visualization of lenticulostriate artery (LSA) by time-of-flight (TOF) magnetic resonance angiography (MRA) with slice-selective off-resonance sinc (SORS) saturation transfer contrast pulses and to compare capability of optimal TOF-MRA and flow-sensitive black-blood (FSBB) MRA to visualize the LSA at 3T. Materials and Methods This study was approved by the local ethics committee, and written informed consent was obtained from all the subjects. TOF-MRA was optimized in 20 subjects by comparing SORS pulses of different flip angles: 0, 400°, and 750°. Numbers of LSAs were counted. The optimal TOF-MRA was compared to FSBB-MRA in 21 subjects. Images were evaluated by the numbers and length of visualized LSAs. Results LSAs were significantly more visualized in TOF-MRA with SORS pulses of 400° than others (P Conclusions LSA visualization was best with 400° SORS pulses for TOF-MRA but FSBB-MRA was better than TOF-MRA, which indicates its clinical potential to investigate the LSA on a 3T magnetic resonance imaging.