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Purpose: To verify the effectiveness of artificial intelligence-assisted volume isotropic simultaneous interleaved bright-/black-blood examination (AI-VISIBLE) for detecting brain metastases., Methods: This retrospective study was approved by our institutional review board and the requirement for written informed consent was waived. Forty patients were included: 20 patients with and without brain metastases each. Seven independent observers (three radiology residents and four neuroradiologists) participated in two reading sessions: in the first, brain metastases were detected using VISIBLE only; in the second, the results of the first session were comprehensively evaluated by adding AI-VISIBLE information. Sensitivity, diagnostic performance, and false positives/case were evaluated. Diagnostic performance was assessed using a figure-of-merit (FOM). Sensitivity and false positives/case were evaluated using McNemar and paired t-tests, respectively., Results: The McNemar test revealed a significant difference between VISIBLE with/without AI information (P < 0.0001). Significantly higher sensitivity (94.9 ± 1.7% vs. 88.3 ± 5.1%, P = 0.0028) and FOM (0.983 ± 0.009 vs. 0.972 ± 0.013, P = 0.0063) were achieved using VISIBLE with AI information vs. without. No significant difference was observed in false positives/case with and without AI information (0.23 ± 0.19 vs. 0.18 ± 0.15, P = 0.250). AI-assisted results of radiology residents became comparable to results of neuroradiologists (sensitivity, FOM: 85.9 ± 3.4% vs. 90.0 ± 5.9%, 0.969 ± 0.016 vs. 0.974 ± 0.012 without AI information; 94.8 ± 1.3% vs. 95.0 ± 2.1%, 0.977 ± 0.010 vs. 0.988 ± 0.005 with AI information, respectively)., Conclusion: AI-VISIBLE improved the sensitivity and performance for diagnosing brain metastases., Competing Interests: Declarations. Ethics approval and consent to participate: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This retrospective study was approved by our Institutional Review Board (Number 24–45). Consent for publication: Not applicable. Competing interests: The authors declare no conflicts of interest related to the content of this article., (© 2024. The Author(s).)

Purpose: This study aimed to compare assessments by radiologists, artificial intelligence (AI), and quantitative measurement using synthetic MRI (SyMRI) for differential diagnosis between astrocytoma, IDH-mutant and oligodendroglioma, and IDH-mutant and 1p/19q-codeleted and to identify the superior method., Methods: Thirty-three cases (men, 14; women, 19) comprising 19 astrocytomas and 14 oligodendrogliomas were evaluated. Four radiologists independently evaluated the presence of the T2-FLAIR mismatch sign. A 3D convolutional neural network (CNN) model was trained using 50 patients outside the test group (28 astrocytomas and 22 oligodendrogliomas) and transferred to evaluate the T2-FLAIR mismatch lesions in the test group. If the CNN labeled more than 50% of the T2-prolonged lesion area, the result was considered positive. The T1/T2-relaxation times and proton density (PD) derived from SyMRI were measured in both gliomas. Each quantitative parameter (T1, T2, and PD) was compared between gliomas using the Mann-Whitney U-test. Receiver-operating characteristic analysis was used to evaluate the diagnostic performance., Results: The mean sensitivity, specificity, and area under the curve (AUC) of radiologists vs. AI were 76.3% vs. 94.7%; 100% vs. 92.9%; and 0.880 vs. 0.938, respectively. The two types of diffuse gliomas could be differentiated using a cutoff value of 2290/128 ms for a combined 90 th percentile of T1 and 10 th percentile of T2 relaxation times with 94.4/100% sensitivity/specificity with an AUC of 0.981., Conclusion: Compared to the radiologists' assessment using the T2-FLAIR mismatch sign, the AI and the SyMRI assessments increased both sensitivity and objectivity, resulting in improved diagnostic performance in differentiating gliomas., (© 2024. The Author(s).)

This study aimed to determine whether quantitative relaxometry using synthetic magnetic resonance imaging (SyMRI) could differentiate between two diffuse glioma groups with isocitrate dehydrogenase (IDH)-mutant tumors, achieving an increased sensitivity compared to the qualitative T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign. Between May 2019 and May 2020, thirteen patients with IDH-mutant diffuse gliomas, including seven with astrocytomas and six with oligodendrogliomas, were evaluated. Five neuroradiologists independently evaluated the presence of the qualitative T2-FLAIR mismatch sign. Interrater agreement on the presence of the T2-FLAIR mismatch sign was calculated using the Fleiss kappa coefficient. SyMRI parameters (T1 and T2 relaxation times and proton density) were measured in the gliomas and compared by the Mann-Whitney U test. Receiver operating characteristic curve analysis was used to evaluate the diagnostic performance. The sensitivity, specificity, and kappa coefficient were 57.1%, 100%, and 0.60, respectively, for the qualitative T2-FLAIR mismatch sign. The two types of diffuse gliomas could be differentiated using a cutoff value of 178 ms for the T2 relaxation time parameter with 100% sensitivity, specificity, accuracy, and positive and negative predictive values, with an area under the curve (AUC) of 1.00. Quantitative relaxometry using SyMRI could differentiate astrocytomas from oligodendrogliomas, achieving an increased sensitivity and objectivity compared to the qualitative T2-FLAIR mismatch sign., (© 2022. The Author(s).)

Objectives: To develop an automated model to detect brain metastases using a convolutional neural network (CNN) and volume isotropic simultaneous interleaved bright-blood and black-blood examination (VISIBLE) and to compare its diagnostic performance with the observer test., Methods: This retrospective study included patients with clinical suspicion of brain metastases imaged with VISIBLE from March 2016 to July 2019 to create a model. Images with and without blood vessel suppression were used for training an existing CNN (DeepMedic). Diagnostic performance was evaluated using sensitivity and false-positive results per case (FPs/case). We compared the diagnostic performance of the CNN model with that of the twelve radiologists., Results: Fifty patients (30 males and 20 females; age range 29-86 years; mean 63.3 ± 12.8 years; a total of 165 metastases) who were clinically diagnosed with brain metastasis on follow-up were used for the training. The sensitivity of our model was 91.7%, which was higher than that of the observer test (mean ± standard deviation; 88.7 ± 3.7%). The number of FPs/case in our model was 1.5, which was greater than that by the observer test (0.17 ± 0.09)., Conclusions: Compared to radiologists, our model created by VISIBLE and CNN to diagnose brain metastases showed higher sensitivity. The number of FPs/case by our model was greater than that by the observer test of radiologists; however, it was less than that in most of the previous studies with deep learning., Key Points: • Our convolutional neural network based on bright-blood and black-blood examination to diagnose brain metastases showed a higher sensitivity than that by the observer test. • The number of false-positives/case by our model was greater than that by the previous observer test; however, it was less than those from most previous studies. • In our model, false-positives were found in the vessels, choroid plexus, and image noise or unknown causes., (© 2021. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To examine the utility of FDG-PET/MRI in patients with epilepsy by comparing the diagnostic accuracy of PET/MRI and PET/CT in epileptogenic zone (EZ) detection., Methods: This prospective study included 31 patients (17 males, 14 females) who underwent surgical resection for EZ. All patients were first scanned using FDG-PET/CT followed immediately with FDG-PET/MRI. Two series of PET plus standalone MR images were interpreted independently by five board-certified radiologists. A 4-point visual score was used to assess image quality. Sensitivities and visual scores from both PETs and standalone MRI were compared using the McNemar test with Bonferroni correction and Dunn's multiple comparisons test., Results: The EZs were confirmed histopathologically via resection as hippocampal sclerosis (n = 11, 35.5%), gliosis (n = 8, 25.8%), focal cortical dysplasia (n = 6, 19.4%), and brain tumours (n = 6, 19.4%) including cavernous haemangioma (n = 3), dysembryoplastic neuroepithelial tumour (n = 1), ganglioglioma (n = 1), and polymorphous low-grade neuroepithelial tumour of the young (n = 1). The sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). The visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT, as well as standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3)., Conclusions: The diagnostic accuracy for the EZ detection in focal epilepsy could be higher in FDG-PET/MRI than in FDG-PET/CT., Key Points: • Sensitivity of FDG-PET/MRI was significantly higher than that of FDG-PET/CT and standalone MRI (FDG-PET/MRI vs. FDG-PET/CT vs. standalone MRI; 77.4-90.3% vs. 58.1-64.5% vs. 45.2-80.6%, p < 0.0001, respectively). • Visual scores derived from FDG-PET/MRI were significantly higher than those of FDG-PET/CT and standalone MRI (2.8 ± 1.2 vs. 2.0 ± 1.1 vs. 2.1 ± 1.2, p < 0.0001, respectively). • Compared to FDG-PET/CT, FDG-PET/MRI increased the visual score (51.9%, increased visual scores of 2 and 3).

The preoperative imaging-based differentiation of primary central nervous system lymphomas (PCNSLs) and glioblastomas (GBs) is of high importance since the therapeutic strategies differ substantially between these tumors. In this study, we investigate whether the gamma distribution (GD) model is useful in this differentiation of PNCSLs and GBs. Twenty-seven patients with PCNSLs and 57 patients with GBs were imaged with diffusion-weighted imaging using 13 b-values ranging from 0 to 1000 sec/mm2. The shape parameter (κ) and scale parameter (θ) were obtained with the GD model. Fractions of three different areas under the probability density function curve (f1, f2, f3) were defined as follows: f1, diffusion coefficient (D) <1.0×10-3 mm2/sec; f2, D >1.0×10-3 and <3.0×10-3 mm2/sec; f3, D >3.0 × 10-3 mm2/sec. The GD model-derived parameters were compared between PCNSLs and GBs. Receiver operating characteristic (ROC) curve analyses were performed to assess diagnostic performance. The correlations with intravoxel incoherent motion (IVIM)-derived parameters were evaluated. The PCNSL group's κ (2.26 ± 1.00) was significantly smaller than the GB group's (3.62 ± 2.01, p = 0.0004). The PCNSL group's f1 (0.542 ± 0.107) was significantly larger than the GB group's (0.348 ± 0.132, p<0.0001). The PCNSL group's f2 (0.372 ± 0.098) was significantly smaller than the GB group's (0.508 ± 0.127, p<0.0001). The PCNSL group's f3 (0.086 ± 0.043) was significantly smaller than the GB group's (0.144 ± 0.062, p<0.0001). The combination of κ, f1, and f3 showed excellent diagnostic performance (area under the curve, 0.909). The f1 had an almost perfect inverse correlation with D. The f2 and f3 had very strong positive correlations with D and f, respectively. The GD model is useful for the differentiation of GBs and PCNSLs., Competing Interests: The authors have declared that no competing interests exist.

Objectives: To evaluate the usefulness of 4D-MR angiography based on super-selective pseudo-continuous ASL combined with keyhole and view-sharing (4D-S-PACK) for vessel-selective visualization and to examine the ability of this technique to visualize brain arteriovenous malformations (AVMs)., Methods: In this retrospective study, 15 patients (ten men and five women, mean age 44.0 ± 16.9 years) with brain AVMs were enrolled. All patients were imaged with 4D-PACK (non-selective), 4D-S-PACK, and digital subtraction angiography (DSA). Observers evaluated vessel selectivity, identification of feeding arteries and venous drainage patterns, visualization scores, and contrast-to-noise ratio (CNR) for each AVM component. Measurements were compared between the MR methods., Results: Vessel selectivity was graded 4 in 43/45 (95.6%, observer 1) and 42/45 (93.3%, observer 2) territories and graded 3 in two (observer 1) and three (observer 2) territories. The sensitivity and specificity for identification of feeding arteries for both observers was 88.9% and 100% on 4D-PACK, and 100% and 100% on 4D-S-PACK, respectively. For venous drainage, the sensitivity and specificity was 100% on both methods for observer 1. The sensitivity and specificity for observer 2 was 94.4% and 83.3% on 4D-PACK, and 94.4% and 91.7% on 4D-S-PACK, respectively. The CNRs at the timepoint of 1600 ms were slightly lower in 4D-S-PACK than in 4D-PACK for all AVM components (Feeding artery, p = .02; nidus, p = .001; and draining artery, p = .02). The visualization scores for both observers were not significantly different between 4D-PACK and 4D-S-PACK for all components., Conclusions: 4D-S-PACK could be a useful non-invasive clinical tool for assessing hemodynamics in brain AVMs., Key Points: • The 4D-MR angiography based on super-selective pseudo-continuous arterial spin labeling combined with CENTRA-keyhole and view-sharing (4D-S-PACK) enabled excellent vessel selectivity. • The 4D-S-PACK enabled the perfect identification of feeding arteries of brain arteriovenous malformation (AVM). • 4D-S-PACK could be a non-invasive clinical tool for assessing hemodynamics in brain AVMs.

Objective: To clarify the relationship between amide proton transfer-weighted (APTW) signal, which reflects intracellular pH, and clinico-radiological findings in patients with hyperacute to subacute cerebral infarction., Materials and Methods: Twenty-nine patients (median age, 70 years [IQR, 54 to 74]; 15 men) were retrospectively examined. The 10th, 25th, 50th, 75th, and 90th percentiles of APTW signal (APT10, APT25, APT50, APT75 and APT90, respectively) were measured within the infarction region-of-interest (ROI), and compared between poor prognosis and good prognosis groups (modified Rankin Scale [mRS] score ≥2 and mRS score <2, respectively). Correlations between APTW signal and time after onset, lesion size, National Institutes of Health Stroke Scale (NIHSS) score, mRS score, and mean apparent diffusion coefficient (ADC) were evaluated., Results: The poor prognosis group had lower APT50, APT75, and APT90 than the good prognosis group (-0.66 [-1.19 to -0.27] vs. -0.09 [-0.62 to -0.21]; -0.27 [-0.63 to -0.01] vs. 0.31 [-0.15 to 1.06]; 0.06 [-0.21 to 0.34] vs. 0.93 [0.36 to 1.50] %; p <0.05, respectively). APT50 was positively correlated with time after onset (r = 0.37, p = 0.0471) and negatively with lesion size (r = -0.39, p = 0.0388). APT75 and APT90 were negatively correlated with NIHSS (r = -0.41 and -0.43; p <0.05, respectively). APT50, APT75 and APT90 were negatively correlated with mRS (r = -0.37, -0.52 and -0.57; p <0.05, respectively). APT10 and APT25 were positively correlated with mean ADC (r = 0.37 and 0.38; p <0.05, respectively)., Conclusion: We demonstrated correlations between APTW signals of infarctions and clinico-radiological findings in patients with hyperacute to subacute infarctions. The poor prognosis group had a lower APTW signal than the good prognosis group. APTW signal was reduced in large infarctions, infarctions with low ADC, and in patients with high NIHSS and mRS scores., Competing Interests: The authors have declared that no competing interests exist.

Objective: To identify abnormalities of regional cerebral blood flow (rCBF) in individuals with obsessive-compulsive disorder (OCD) by conducting a voxel-based analysis of pseudo-continuous arterial spin labeling (pCASL) perfusion images., Materials and Methods: This prospective study included 23 OCD patients (nine males, 14 females; age 21-62 years; mean ± SD 37.2 ± 10.7 years) diagnosed based on DSM-IV-TR criteria and 64 healthy controls (27 males, 37 females; age 20-64 years; mean ± SD 38.3 ± 12.8 years). Subjects were recruited from October 2011 to August 2017. Imaging was performed on a 3T scanner. Quantitative rCBF maps generated from pCASL images were co-registered and resliced with the three-dimensional T1-weighted images, and then spatially normalized to a brain template and smoothed. We used statistical nonparametric mapping to assess the differences in rCBF and gray matter volume between the OCD and control groups. The significance level was set at the p-value <0.05 with family-wise error rate correction for multiple comparisons., Results: Compared to the control group, there were significant rCBF reductions in the right putamen, right frontal operculum, left midcingulate cortex, and right temporal pole in the OCD group. There were no significant between-group differences in the gray matter volume., Conclusion: The pCASL imaging noninvasively detected physiologically disrupted areas without structural abnormalities in OCD patients. The rCBF reductions observed in these regions in OCD patients could be associated with the pathophysiology of OCD., Competing Interests: We have declared that no competing interests exist.

Purpose: Diffusion-weighted imaging (DWI) plays an important role in the preoperative assessment of gliomas; however, the diagnostic performance of histogram-derived parameters from mono-, bi-, and stretched-exponential DWI models in the grading of gliomas has not been fully investigated. Therefore, we compared these models' ability to differentiate between high-grade and low-grade gliomas., Methods: This retrospective study included 22 patients with diffuse gliomas (age, 23-74 years; 12 males; 11 high-grade and 11 low-grade gliomas) who underwent preoperative 3 T-magnetic resonance imaging from October 2014 to August 2019. The apparent diffusion coefficient was calculated from the mono-exponential model. Using 13 b-values, the true-diffusion coefficient, pseudo-diffusion coefficient, and perfusion fraction were obtained from the bi-exponential model, and the distributed-diffusion coefficient and heterogeneity index were obtained from the stretched-exponential model. Region-of-interests were drawn on each imaging parameter map for subsequent histogram analyses., Results: The skewness of the apparent diffusion, true-diffusion, and distributed-diffusion coefficients was significantly higher in high-grade than in low-grade gliomas (0.67 ± 0.67 vs. - 0.18 ± 0.63, 0.68 ± 0.74 vs. - 0.08 ± 0.66, 0.63 ± 0.72 vs. - 0.15 ± 0.73; P = 0.0066, 0.0192, and 0.0128, respectively). The 10th percentile of the heterogeneity index was significantly lower (0.77 ± 0.08 vs. 0.88 ± 0.04; P = 0.0004), and the 90th percentile of the perfusion fraction was significantly higher (12.64 ± 3.44 vs. 7.14 ± 1.70%: P < 0.0001), in high-grade than in low-grade gliomas. The combination of the 10th percentile of the true-diffusion coefficient and 90th percentile of the perfusion fraction showed the best area under the receiver operating characteristic curve (0.96)., Conclusion: The bi-exponential model exhibited the best diagnostic performance for differentiating high-grade from low-grade gliomas.

Purpose: To evaluate the performance of acceleration-selective arterial spin labeling (AccASL) MR angiography in the visualization of brain arteriovenous malformations (AVMs) in comparison with digital subtraction angiography (DSA) and time-of-flight (TOF) MR angiography., Methods: Twenty-one patients with brain AVM (mean age 31.1 ± 18.6 years; 11 males, 10 females) underwent TOF and AccASL MR angiography and DSA. Two neuroradiologists conducted an observer study for detection, nidus size, eloquence, venous drainage pattern, and Spetzler-Martin (SM) grade. The evaluations included the visualization of each AVM component with reference to DSA and assessments of contrast-to-noise ratio (CNR). The kappa statistic, repeated measures analysis of variance, Wilcoxon matched pairs test, and paired t test were used., Results: Both observers detected more AVMs with AccASL (95.2%, 90.5% for Observers 1 and 2) than with TOF (76.2% and 71.4%, respectively). The inter-modality agreement between AccASL and DSA was almost perfect for the eloquence, venous drainage pattern, and SM grade for Observer 1 and moderate for the venous drainage pattern and substantial for the eloquence and SM grade for Observer 2. The visualization scores were higher with AccASL than with TOF for the feeding artery (AccASL, 4.5 ± 1.0 vs. TOF, 3.9 ± 1.5, p = 0.0214), nidus (4.6 ± 1.1 vs. 3.2 ± 1.5, p = 0.0006), and draining vein (4.6 ± 1.0 vs. 2.2 ± 1.1, p < 0.0001), respectively. The CNRs in the nidus were higher in AccASL than in TOF (29.9 ± 16.7 vs. 20.8 ± 16.5, p = 0.0002), as in the draining vein (23.2 ± 13.0 vs. 12.6 ± 12.0, p = 0.0010), respectively., Conclusions: AccASL better visualized brain AVMs compared with TOF and was useful for grading without the use of contrast agents.

Computed DWI (cDWI) is a mathematical technique that calculates arbitrary higher b value images from at least two different lower b values. In addition, the removal of high intensity noise with image processing on cDWI could improve cholesteatoma-background contrast-to-noise ratio (CNR). In the present study, noise reduction was performed by the cut-off values of apparent diffusion coefficient (ADC) less than 0 and 0.4 × 10 -3 s/mm 2 . The cholesteatoma to non-cholesteatoma CNR was increased using a noise reduction algorithm for clinical setting.

Background and Purpose: Intravoxel incoherent motion imaging, which simultaneously measures diffusion and perfusion parameters, is promising for brain tumor grading. However, intravoxel incoherent motion imaging has not been tested in children. The purpose of this study was to evaluate the correlation between intravoxel incoherent motion parameters and histology to assess the accuracy of intravoxel incoherent motion imaging for pediatric intracranial tumor grading., Materials and Methods: Between April 2013 and September 2015, 17 children (11 boys, 6 girls; 2 months to 15 years of age) with intracranial tumors were included in this retrospective study. Intravoxel incoherent motion parameters were fitted using 13 b-values for a biexponential model. The perfusion-free diffusion coefficient, pseudodiffusion coefficient, and perfusion fraction were measured in high- and low-grade tumors. These intravoxel incoherent motion parameters and the ADC were compared using the unpaired t test. The correlations between the intravoxel incoherent motion parameters and microvessel density or the MIB-1 index were analyzed using the Spearman correlation test. Receiver operating characteristic analysis was used to evaluate diagnostic performance., Results: The perfusion-free diffusion coefficient and ADC were lower in high-grade than in low-grade tumors (perfusion-free diffusion coefficient, 0.85 ± 0.40 versus 1.53 ± 0.21 × 10 -3 mm 2 /s, P < .001; ADC, 1.04 ± 0.33 versus 1.60 ± 0.21 × 10 -3 mm 2 /s, P < .001). The pseudodiffusion coefficient showed no difference between the groups. The perfusion fraction was higher in high-grade than in low-grade tumors (21.7 ± 8.2% versus 7.6 ± 4.3%, P < .001). Receiver operating characteristic analysis found that the combined perfusion-free diffusion coefficient and perfusion fraction had the best diagnostic performance for tumor differentiation (area under the curve = 0.986)., Conclusions: Intravoxel incoherent motion imaging reflects tumor histology and may be a helpful, noninvasive method for pediatric intracranial tumor grading., (© 2019 by American Journal of Neuroradiology.)

Purpose: MR neurography is known to be useful to evaluate nerve pathology. The purpose of this study was to evaluate the usefulness of simultaneous apparent T2 mapping and neurography with nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement imaging (SHINKEI) to distinguish patients with chronic inflammatory demyelinating polyneuropathy (CIDP) from healthy subjects., Materials and Methods: This retrospective study included 13 patients with CIDP and five healthy subjects from 2015 to 2017. The T2 relaxation time and the size of the cervical ganglia and roots of the brachial plexus were measured. Statistical analyses were performed with the Mann-Whitney U test and receiver operating characteristics (ROC) analysis., Results: The T2 relaxation times of the ganglia and roots were longer in patients with CIDP (119.31 ± 35.53 msec and 111.15 ± 33.82 msec) than in healthy subjects (101.42 ± 26.42 msec and 85.29 ± 13.22 msec, P = 0.0007 and P < 0.0001, respectively). The sizes of the ganglia and the roots were larger in patients with CIDP (6.25 ± 1.56 mm and 4.37 ± 1.71 mm) than in healthy subjects (5.59 ± 1.08 mm and 3.50 ± 0.62 mm, P = 0.0114 and P = 0.0014, respectively). ROC analysis revealed that T2 relaxation time of the roots was best at distinguishing CIDP patients from healthy subjects (the area under the curve = 0.748)., Conclusion: Patients with CIDP could be distinguished from healthy subjects using simultaneous apparent T2 mapping and neurography with SHINKEI., (Copyright © 2018 Elsevier Inc. All rights reserved.)

In this study, we evaluated the efficacy of intravoxel incoherent motion (IVIM)-derived parameters calculated with three b-values in differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs) by comparing those calculated with multiple b-values. Ten patients with LGG (ages 35.1±12.1 yrs; 4 males, 6 females) and 21 patients with HGG (ages 60.6±19.1 yrs; 10 males, 11 females) who underwent subsequent surgical resections were examined with both IVIM imaging and histopathological analysis. The IVIM diffusion-weighted imaging was conducted using a single-shot echo planar sequence with 13 b-factors (0, 10, 20, 30, 50, 80, 100, 200, 300, 400, 600, 800, and 1000 sec/mm2) at 3T. In the conventional IVIM analysis, the perfusion fraction (f) and true diffusion coefficient (D) were calculated by biexponential fitting model with 13 b-values. In the simplified method with the selected three b-values (0, 300, and 1000 sec/mm2), D simply corresponds to the slope of a straight line passing through two logarithmic signal intensities (SIs) at the b-values of 300 and 1000 s/mm2, and f corresponds to the difference between the intercept of this line and SI at the b-value of 0 sec/mm2. The maximum f (f-max) and minimum D (D-min) was measured in each tumor. The f-max values calculated with three b-values (12.8±5.9%) were significantly lower than those with 13 b-values (17.3±7.5%, p<0.0001), but a good correlation and agreement were observed between these sets of f-max values (r = 0.79, ICC = 0.87). In the IVIM imaging with both three and 13 b-values, the HGGs showed significantly higher f-max values compared to the LGGs (p<0.001, respectively). The D-min values calculated with three b-values (1.06±0.31 ×10-3 mm2/sec) was not different from those with 13 b-values (1.07±0.33 ×10-3 mm2/sec), and an excellent correlation and agreement were found between them (r = 0.99, ICC = 0.99). The simplified IVIM imaging using three b-values can efficiently differentiate HGGs and LGGs., Competing Interests: The authors have declared that no competing interests exist.

Objective:: To evaluate the usefulness of simultaneous T 2 mapping and neurography with nerve-sheath signal increased with inked rest-tissue rapid acquisition of relaxation enhancement imaging (SHINKEI) in the lumbar plexus to distinguish patients with chronic inflammatory demyelinating polyneuropathy (CIDP) from healthy controls., Methods:: Our institutional review boards approved this retrospective study, and written informed consent was waived. 10 patients with CIDP from 2015 to 2017 were studied along with 5 healthy controls on a 3 T scanner. The T 2 relaxation time and the size of the dorsal root ganglia and nerves of the lumbar plexus at L3-S1 were measured. Statistical analyses were performed with the Mann-Whitney U test and a receiver operating characteristics analysis., Results:: The T 2 relaxation times of the dorsal root ganglia and the nerves of the lumbar plexus were longer in the CIDP patients (133.34  ±  41.36 and 130.40 ± 47.78 ms) compared to the healthy controls (114.69 ± 24.90 and 83.72 ± 17.51 ms, p = 0.0265 and p < 0.0001, respectively). The sizes of the nerves were larger in the CIDP patients (6.19  ±  2.28 mm) compared to the controls (4.54  ±  0.86 mm, p < 0.0001). However, there was no significant difference between the sizes of the ganglia in the CIDP patients and the controls. The receiver operating characteristics analysis revealed that the T 2 relaxation time of the nerves was best at distinguishing the CIDP patients from the controls (Az  =  0.848)., Conclusion:: Patients with CIDP could be distinguished from healthy controls using simultaneous T 2 mapping and neurography with SHINKEI in the lumbar plexus., Advances in Knowledge:: Patients with CIDP could be distinguished from healthy controls using simultaneous T 2 mapping and neurography with SHINKEI in the lumbar plexus.

Objective: Ultrahigh-resolution CT (U-HRCT) provides better spatial resolution than conventional multi-detector row CT (ConvCT) and could be expected to identify microstructures with its 0.25-mm collimation, 1792 channels and 160 detector rows, 0.4 × 0.5 mm focus size, and a 1024 matrix. The aim of the study was to evaluate key anatomic structures in temporal bone using U-HRCT comparing it to ConvCT., Materials and Methods: A total of 30 patients (14 males and 16 females; age range, 8-82 years; median 49 years) underwent both U-HRCT and ConvCT. All CT images were obtained with 0.5 mm section thickness and a 512 × 512 matrix, and field of view of 80 mm. Transverse scans were acquired in a plane parallel to the orbitomeatal plane in the helical mode with 120 kV. Images of the 30 temporal bones of unaffected side were reviewed by two independent neuroradiologists who rated the visibility of key anatomic structures for both U-HRCT and ConvCT. The ratings between U-HRCT and ConvCT were compared using Wilcoxon matched-pairs signed rank test. The interobserver agreement on the rating of stapedius tendon was evaluated using weighted κ statistics., Results: Excellent interobserver agreement was shown for U-HRCT (κ = 0.920), whereas good agreement was obtained for ConvCT (κ = 0.733). According to both observers, stapedius tendon was more clearly visualized using U-HRCT than ConvCT (p < 0.0001). All other anatomic structures were well visualized using both CT scanners., Conclusion: The anatomy of temporal bone is more conspicuous on U-HRCT than on ConvCT because of its ultra-high-resolution detector. U-HRCT may provide beneficial information for determining surgical indication or procedures.

Objectives: To evaluate the performance of four-dimensional pseudo-continuous arterial spin labeling (4D-pCASL)-based angiography using CENTRA-keyhole and view sharing (4D-PACK) in the visualization of flow dynamics in distal cerebral arteries and leptomeningeal anastomosis (LMA) collaterals in moyamoya disease in comparison with contrast inherent inflow-enhanced multiphase angiography (CINEMA), with reference to digital subtraction angiography (DSA)., Methods: Thirty-two cerebral hemispheres from 19 patients with moyamoya disease (mean age, 29.7 ± 19.6 years; five males, 14 females) underwent both 4D-MR angiography and DSA. Qualitative evaluations included the visualization of anterograde middle cerebral artery (MCA) flow and retrograde flow via LMA collaterals with reference to DSA. Quantitative evaluations included assessments of the contrast-to-noise ratio (CNR) on these vessels. The linear mixed-effect model was used to compare the 4D-PACK and CINEMA methods., Results: The vessel visualization scores were significantly higher with 4D-PACK than with CINEMA in the visualization of anterograde flow for both Observer 1 (CINEMA, 3.53 ± 1.39; 4D-PACK, 4.53 ± 0.80; p < 0.0001) and Observer 2 (CINEMA, 3.50±1.39; 4D-PACK, 4.31 ± 0.86; p = 0.0009). The scores were higher with 4D-PACK than with CINEMA in the visualization of retrograde flow for both Observer 1 (CINEMA, 3.44 ± 1.05; 4D-PACK, 4.47 ± 0.88; p < 0.0001) and Observer 2 (CINEMA, 3.19 ± 1.20; 4D-PACK, 4.38 ± 0.91; p < 0.0001). The maximum CNR in the anterograde flow was higher in 4D-PACK (40.1 ± 16.1, p = 0.0001) than in CINEMA (27.0 ± 16.6). The maximum CNR in the retrograde flow was higher in 4D-PACK (36.1 ± 10.0, p < 0.0001) than in CINEMA (15.4 ± 8.0)., Conclusions: The 4D-PACK provided better visualization and higher CNRs in distal cerebral arteries and LMA collaterals compared with CINEMA in patients with this disease., Key Points: • The 4D-PACK enables good visualization of distal cerebral arteries in moyamoya disease. • The 4D-PACK enables direct visualization of leptomeningeal collateral vessels in moyamoya disease. • Vessel visualization by 4D-PACK can be useful in assessing cerebral hemodynamics.

Objective: To evaluate the quantification performance of the perfusion fraction (f) measured with intravoxel incoherent motion (IVIM) MR imaging in a comparison with the histological vascular density in meningiomas., Methods: 29 consecutive patients with meningioma (59.0 ± 16.8 years old, 8 males and 21 females) who underwent a subsequent surgical resection were examined with both IVIM imaging and a histopathological analysis. IVIM imaging was conducted using a single-shot SE-EPI sequence with 13 b-factors (0, 10, 20, 30, 50, 80, 100, 200, 300, 400, 600, 800, 1000 s mm - 2 ) at 3T. The perfusion fraction (f) was calculated by fitting the IVIM bi-exponential model. The 90-percentile f-value in the tumor region-of-interest (ROI) was defined as the maximum f-value (f-max). Histopathological vascular density (%Vessel) was measured on CD31-immunostainted histopathological specimens. The correlation and agreement between the f-values and %Vessel was assessed., Results: The f-max (15.5 ± 5.5%) showed excellent agreement [intraclass correlation coefficient (ICC) = 0.754] and a significant correlation (r = 0.69, p < 0.0001) with the %Vessel (12.9 ± 9.4%) of the tumors. The Bland-Altman plot analysis showed excellent agreement between the f-max and %Vessel (bias, -2.6%; 95% limits of agreement, from -16.0 to 10.8%). The f-max was not significantly different among the histological subtypes of meningioma., Conclusion: An excellent agreement and a significant correlation were observed between the f-values and %Vessel. The f-value can be used as a noninvasive quantitative imaging measure to directly assess the vascular volume fraction in brain tumors. Advances in knowledge: The f-value measured by IVIM imaging showed a significant correlation and an excellent agreement with the histological vascular density in the meningiomas. The f-value can be used as a noninvasive and quantitative imaging measure to directly assess the volume fraction of capillaries in brain tumors.

Purpose: To evaluate whether 3D SHINKEI in the lumbar plexus could identify patients with chronic inflammatory demyelinating polyneuropathy (CIDP)., Materials and Methods: Twenty-one patients with CIDP and 15 non-CIDP patients were studied in this retrospective study. The SNR, contrast-to-noise ratio (CNR), contrast ratio (CR) and the size of the lumbar ganglions and roots were measured. Statistical analyses were performed with Mann-Whitney U test and receiver operating characteristics (ROC) analysis., Results: The SNRs of the ganglions and roots were larger in patients with CIDP (8.30±4.87 and 8.24±4.92) than in non-CIDP patients (4.95±2.05 and 5.08±1.97, P<0.0001, respectively). The CNRs of the ganglions and roots were larger in patients with CIDP (40.79±43.19 and 37.16±48.31) than in non-CIDP patients (25.90±10.41 and 18.37±32.83, P<0.0001, respectively). The CRs of the ganglions and roots were larger in patients with CIDP (0.74±0.13 and 0.66±0.17) than in non-CIDP patients (0.72±0.12 and 0.50±0.17, P=0.004 and P<0.0001, respectively). The sizes of the ganglions and the roots were larger in patients with CIDP (6.62±1.81mm and 5.76±3.24mm) than in non-CIDP patients (5.23±1.17mm and 4.24±1.11mm, P<0.0001, respectively). ROC analysis showed the best diagnostic performance with the CNR of the roots., Conclusion: Patients with CIDP could be distinguished from controls on 3D SHINKEI., (Copyright © 2017. Published by Elsevier B.V.)