Altered Brain Glymphatic Flow at Diffusion-Tensor MRI in Rapid Eye Movement Sleep Behavior Disorder.

Background Brain glymphatic dysfunction may contribute to the development of α-synucleinopathies. Yet, noninvasive imaging and quantification remain lacking. Purpose To examine glymphatic function of the brain in isolated rapid eye movement sleep behavior disorder (RBD) and its relevance to phenoconversion with use of diffusion-tensor imaging (DTI) analysis along the perivascular space (ALPS). Materials and Methods This prospective study included consecutive participants diagnosed with RBD, age- and sex-matched control participants, and participants with Parkinson disease (PD) who were enrolled and examined between May 2017 and April 2020. All study participants underwent 3.0-T brain MRI including DTI, susceptibility-weighted and susceptibility map-weighted imaging, and/or dopamine transporter imaging using iodine 123-2ß-carbomethoxy-3ß-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane SPECT at the time of participation. Phenoconversion status to α-synucleinopathies was unknown at the time of MRI. Participants were regularly followed up and monitored for any signs of α-synucleinopathies. The ALPS index reflecting glymphatic activity was calculated by a ratio of the diffusivities along the x-axis in the projection and association neural fibers to the diffusivities perpendicular to them and compared according to the groups with use of the Kruskal-Wallis and Mann-Whitney U tests. The phenoconversion risk in participants with RBD was evaluated according to the ALPS index with use of a Cox proportional hazards model. Results Twenty participants diagnosed with RBD (12 men; median age, 73 years [IQR, 66-76 years]), 20 control participants, and 20 participants with PD were included. The median ALPS index was lower in the group with RBD versus controls (1.53 vs 1.72; P = .001) but showed no evidence of a difference compared with the group with PD (1.49; P = .68). The conversion risk decreased with an increasing ALPS index (hazard ratio, 0.57 per 0.1 increase in the ALPS index [95% CI: 0.35, 0.93]; P = .03). Conclusion DTI-ALPS in RBD demonstrated a more severe reduction of glymphatic activity in individuals with phenoconversion to α-synucleinopathies. © RSNA, 2023 Supplemental material is available for this article. See also the editorial by Filippi and Balestrino in this issue.

Deep learning regressor model based on nigrosome MRI in Parkinson syndrome effectively predicts striatal dopamine transporter-SPECT uptake.

PURPOSE: Nigrosome imaging using susceptibility-weighted imaging (SWI) and dopamine transporter imaging using 123I-2ß-carbomethoxy-3ß-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane (123I-FP-CIT) single-photon emission computerized tomography (SPECT) can evaluate Parkinsonism. Nigral hyperintensity from nigrosome-1 and striatal dopamine transporter uptake are reduced in Parkinsonism; however, quantification is only possible with SPECT. Here, we aimed to develop a deep-learning-based regressor model that can predict striatal 123I-FP-CIT uptake on nigrosome magnetic resonance imaging (MRI) as a biomarker for Parkinsonism. METHODS: Between February 2017 and December 2018, participants who underwent 3 T brain MRI including SWI and 123I-FP-CIT SPECT based on suspected Parkinsonism were included. Two neuroradiologists evaluated the nigral hyperintensity and annotated the centroids of nigrosome-1 structures. We used a convolutional neural network-based regression model to predict striatal specific binding ratios (SBRs) measured via SPECT using the cropped nigrosome images. The correlation between measured and predicted SBRs was evaluated. RESULTS: We included 367 participants (203 women (55.3%); age, 69.0 ± 9.2 [range, 39-88] years). Random data from 293 participants (80%) were used for training. In the test set (74 participants [20%]), the measured and predicted 123I-FP-CIT SBRs were significantly lower with the loss of nigral hyperintensity (2.31 ± 0.85 vs. 2.44 ± 0.90) than with intact nigral hyperintensity (4.16 ± 1.24 vs. 4.21 ± 1.35, P < 0.01). The sorted measured 123I-FP-CIT SBRs and the corresponding predicted values were significantly and positively correlated (ρc = 0.7443; 95% confidence interval, 0.6216-0.8314; P < 0.01). CONCLUSION: A deep learning-based regressor model effectively predicted striatal 123I-FP-CIT SBRs based on nigrosome MRI with high correlation using manually-measured values, enabling nigrosome MRI as a biomarker for nigrostriatal dopaminergic degeneration in Parkinsonism.

Diagnostic assessment of magnetic resonance imaging for patients with intralabyrinthine schwannoma: A systematic review.

OBJECTIVES: Recent advancements in high-resolution imaging have improved the diagnostic assessment of magnetic resonance imaging (MRI) for intralabyrinthine schwannoma (ILS). This systematic review aimed to evaluate the diagnostic performance of MRI for patients with ILS. METHODS: Ovid-MEDLINE and EMBASE databases were searched for related studies on the diagnostic performance of MRI for patients with ILS published up to February 10, 2020. The primary endpoint was the diagnostic performance of MRI for ILS. The quality of the enrolled studies was assessed using tailored questionnaires and the Quality Assessment of Diagnostic Accuracy Studies-2 criteria. RESULTS: Overall, 6 retrospective studies that included 122 patients with ILS from a parent population of 364 were included. The sample size, parent population and its composition, reference standard, detailed parameters of MRI, and even the diagnostic methods varied between the studies. The studies had moderate quality. The sensitivity of combination of T2WI and CE-T1WI was over 90%. Relative sensitivity of T2WI comparative to CE-T1WI ranged from 62% to 100%, and the specificity were 100%. CONCLUSIONS: MRI has acceptable diagnostic performance for ILS. There is a need for well-organized research to reduce the factors causing heterogeneity.

Imaging the Substantia Nigra in Parkinson Disease and Other Parkinsonian Syndromes.

Parkinson disease is characterized by dopaminergic cell loss in the substantia nigra of the midbrain. There are various imaging markers for Parkinson disease. Recent advances in MRI have enabled elucidation of the underlying pathophysiologic changes in the nigral structure. This has contributed to accurate and early diagnosis and has improved disease progression monitoring. This article aims to review recent developments in nigral imaging for Parkinson disease and other parkinsonian syndromes, including nigrosome imaging, neuromelanin imaging, quantitative iron mapping, and diffusion-tensor imaging. In particular, this article examines nigrosome imaging using 7-T MRI and 3-T susceptibility-weighted imaging. Finally, this article discusses volumetry and its clinical importance related to symptom manifestation. This review will improve understanding of recent advancements in nigral imaging of Parkinson disease. Published under a CC BY 4.0 license.

Diagnostic performance of neuromelanin-sensitive magnetic resonance imaging for patients with Parkinson's disease and factor analysis for its heterogeneity: a systematic review and meta-analysis.

OBJECTIVE: To determine the diagnostic performance of neuromelanin-sensitive magnetic resonance imaging discriminating between patients with Parkinson's disease and normal healthy controls and to identify factors causing heterogeneity influencing the diagnostic performance. METHODS: A systematic literature search in the Ovid-MEDLINE and EMBASE databases was performed for studies reporting the relevant topic before February 17, 2020. The pooled sensitivity and specificity values with their 95% confidence intervals were calculated using bivariate random-effects modeling. Subgroup and meta-regression analyses were also performed to determine factors influencing heterogeneity. RESULTS: Twelve articles including 403 patients with Parkinson's disease and 298 control participants were included in this systematic review and meta-analysis. Neuromelanin-sensitive magnetic resonance imaging showed a pooled sensitivity of 89% (95% confidence interval, 86-92%) and a pooled specificity of 83% (95% confidence interval, 76-88%). In the subgroup and meta-regression analysis, a disease duration longer than 5 and 10 years, comparisons using measured volumes instead of signal intensities, a slice thickness in terms of magnetic resonance imaging parameters of more than 2 mm, and semi-/automated segmentation methods instead of manual segmentation improved the diagnostic performance. CONCLUSION: Neuromelanin-sensitive magnetic resonance imaging had a favorable diagnostic performance in discriminating patients with Parkinson's disease from healthy controls. To improve diagnostic accuracy, further investigations directly comparing these heterogeneity-affecting factors and optimizing these parameters are necessary. KEY POINTS: • Neuromelanin-sensitive MRI favorably discriminates patients with Parkinson's disease from healthy controls. • Disease duration, parameters used for comparison, magnetic resonance imaging slice thickness, and segmentation methods affected heterogeneity across the studies.

Diagnostic performance of MRI of post-laminar optic nerve invasion detection in retinoblastoma: A systematic review and meta-analysis.

PURPOSE: Preoperative MRI detection of post-laminar optic nerve invasion (PLONI) offers guidance in assessing the probability of total tumor resection, an estimation of the extent of surgery, and screening of candidates for eye-preserving therapies or neoadjuvant chemotherapies in the patients with retinoblastoma (RB). The purpose of this systematic review and meta-analysis was to evaluate the diagnostic performance of MRI for detecting PLONI in patients with RB and to demonstrate the factors that may influence the diagnostic performance. METHODS: Ovid-MEDLINE and EMBASE databases were searched up to January 11, 2020, for studies identifying the diagnostic performance of MRI for detecting PLONI in patients with RB. The pooled sensitivity and specificity of all studies were calculated followed by meta-regression analysis. RESULTS: Twelve (1240 patients, 1255 enucleated globes) studies were included. The pooled sensitivity was 61%, and the pooled specificity was 88%. Higgins I2 statistic demonstrated moderate heterogeneity in the sensitivity (I2 = 72.23%) and specificity (I2 = 78.11%). Spearman correlation coefficient indicated the presence of a threshold effect. In the meta-regression, higher magnetic field strength (3 T than 1.5 T), performing fat suppression, and thinner slice thickness (< 3 mm) were factors causing heterogeneity and enhancing diagnostic power across the included studies. CONCLUSIONS: MR imaging was demonstrated to have acceptable diagnostic performance in detecting PLONI in patients with RB. The variation in the magnetic field strength and protocols was the main factor behind the heterogeneity across the included studies. Therefore, there is room for developing and optimizing the MR protocols for patients with RB.

Altered brain function in persistent postural perceptual dizziness: A study on resting state functional connectivity.

This study used resting state functional magnetic resonance imaging (rsfMRI) to investigate whole brain networks in patients with persistent postural perceptual dizziness (PPPD). We compared rsfMRI data from 38 patients with PPPD and 38 healthy controls using whole brain and region of interest analyses. We examined correlations among connectivity and clinical variables and tested the ability of a machine learning algorithm to classify subjects using rsfMRI results. Patients with PPPD showed: (a) increased connectivity of subcallosal cortex with left superior lateral occipital cortex and left middle frontal gyrus, (b) decreased connectivity of left hippocampus with bilateral central opercular cortices, left posterior opercular cortex, right insular cortex and cerebellum, and (c) decreased connectivity between right nucleus accumbens and anterior left temporal fusiform cortex. After controlling for anxiety and depression as covariates, patients with PPPD still showed decreased connectivity between left hippocampus and right inferior frontal gyrus, bilateral temporal lobes, bilateral insular cortices, bilateral central opercular cortex, left parietal opercular cortex, bilateral occipital lobes and cerebellum (bilateral lobules VI and V, and left I-IV). Dizziness handicap, anxiety, and depression correlated with connectivity in clinically meaningful brain regions. The machine learning algorithm correctly classified patients and controls with a sensitivity of 78.4%, specificity of 76.9%, and area under the curve = 0.88 using 11 connectivity parameters. Patients with PPPD showed reduced connectivity among the areas involved in multisensory vestibular processing and spatial cognition, but increased connectivity in networks linking visual and emotional processing. Connectivity patterns may become an imaging biomarker of PPPD.

MRI Features and IDH Mutational Status of Grade II Diffuse Gliomas: Impact on Diagnosis and Prognosis.

OBJECTIVE: Grade II diffuse gliomas (DGs) with isocitrate dehydrogenase (IDH) mutations are associated with better prognosis than their IDH wild-type counterparts. We sought to determine the MRI characteristics associated with IDH mutational status and ascertain whether MRI considered in combination with IDH mutational status can better predict the clinical outcomes of grade II DGs. MATERIALS AND METHODS: Preoperative MRI examinations were retrospectively studied for qualitative tumor characteristics, including location, extent, cortical involvement, margin sharpness, cystic component, mineralization or hemorrhage, and contrast enhancement. Quantitative diffusion and perfusion metrics were also assessed. Logistic regression and ROC analyses were used to evaluate the relationship between MRI features and IDH mutational status. The association between IDH mutational status, 1p19q codeletion, MRI features, extent of resection, and clinical outcomes was assessed by Kaplan-Meier and Cox proportional hazards models. RESULTS: Of 100 grade II DGs, 78 were IDH mutant and 22 were IDH wild type. IDH wild-type tumors were associated with older age, multifocality, brainstem involvement, lack of cystic change, and a lower apparent diffusion coefficient (ADC). Multivariable regression showed that age older than 45 years as well as low minimum ADC (ADCmin), mean ADC, and maximum ADC values were independently associated with IDH mutational status. Of these, an ADCmin threshold of 0.9 × 10-3 mm2/s or less provided the greatest sensitivity and specificity (91% and 76%, respectively) in defining IDH wild-type grade II DGs. Combining low ADCmin with IDH wild-type status conferred worse outcomes than did IDH wild-type status alone. CONCLUSION: IDH wild-type grade II DGs are associated with a lower ADC and poor clinical outcomes. Combining IDH mutational status and ADC may allow more accurate prediction of clinical outcomes for patients with grade II DGs.

Early Stage of Hyperintense Acute Reperfusion Marker on Contrast-Enhanced FLAIR Images in Patients With Acute Stroke.

OBJECTIVE: Hyperintense acute reperfusion marker (HARM) is defined as delayed CSF enhancement on FLAIR images in patients with acute stroke and was observed in follow-up FLAIR images after initial MRI with contrast material administration. We hypothesized that different imaging findings of HARM could be present depending on the timing of FLAIR imaging after contrast material administration. SUBJECTS AND METHODS: Of 218 consecutive patients with acute stroke or transient ischemic attack over 3 months, 12 with linear contrast enhancement on the cortical surface in initial FLAIR images underwent serial FLAIR imaging. Initial FLAIR images were obtained 5 minutes after contrast material administration, and follow-up unenhanced FLAIR images were obtained 2.5-29 hours (mean, 13.2 hours) after initial FLAIR imaging. The enhancement patterns between initial and follow-up FLAIR images were compared. RESULTS: In all 12 patients, initial contrast-enhanced FLAIR images showed focal or multifocal linear contrast enhancement along the cortical surface near acute infarctions. On follow-up unenhanced FLAIR images, initial cortical enhancement spread diffusely and filled the subarachnoid space. CONCLUSION: HARM in acute stroke can be detected earlier than previously reported on initial contrast-enhanced FLAIR images. Different imaging findings of HARM depend on the timing of FLAIR imaging after contrast material administration.

Time of flight MR angiography assessment casts doubt on the association between transient global amnesia and intracranial jugular venous reflux.

PURPOSE: Evidence of intracranial venous reflux flow due to jugular venous reflux (JVR) on time of flight (TOF) MR angiography (MRA) is thought to be highly associated with transient global amnesia (TGA)-evidence that supports the venous congestion theory of TGA pathophysiology. However, recent studies indicate that intracranial JVR on TOF MRA is occasionally observed in normal elderly. Therefore, the purpose of this study was to compare the prevalence of intracranial JVR on TOF MRA in patients with TGA and two control groups. METHODS: Three age- and sex-matched groups of subjects that received MRI and MRA were enrolled. The groups comprised 167 patients with TGA, 167 visitors to the emergency room (ER) and 167 visitors to a health promotion centre (HPC). Intracranial JVR was defined as abnormal venous signals in the inferior petrosal, sigmoid and/or transverse sinuses on TOF MRA. The prevalence of intracranial JVR was assessed across the three groups. RESULTS: Intracranial JVR was seen in seven (4.2 %) TGA patients, eight (4.8 %) ER visitors and three (1.8 %) HPC visitors, respectively. No statistically significant differences were observed among the three groups. CONCLUSION: TGA patients showed a low prevalence of intracranial JVR on TOF MRA, and no statistical differences were found in comparison with control groups.

MRI and MR angiography findings to differentiate jugular venous reflux from cavernous dural arteriovenous fistula.

OBJECTIVE: Both jugular venous reflux (JVR) and cavernous dural arteriovenous fistula (DAVF) manifest as abnormal venous signal intensities on time-of-flight (TOF) MR angiography (MRA). We investigated brain MRI and MRA findings that might differentiate JVR from cavernous DAVF. MATERIALS AND METHODS: Forty-one patients with abnormal venous signal intensities on TOF MRA in the cavernous sinus and its vicinity were selected from 1508 patients who had undergone TOF MRA over the previous 6 months. For comparison, the examinations of 26 patients with cavernous DAVF who had undergone imaging over the previous 8 years were collected. The following findings were assessed: the side and location of abnormal venous signal intensities on intracranial TOF MRA; the signal intensity of the proximal jugular vein on T2-weighted imaging; whether there was early opacification of the cavernous sinus in the arterial phase of contrast-enhanced MRA (CE-MRA); the side of jugular venous drainage in the arteriovenous phase of CE-MRA; and whether retrograde jugular venous flow was seen on neck TOF MRA. RESULTS: Abnormal venous signal intensities were seen on the left side in 73% of patients with JVR and 58% of patients with cavernous DAVF; involvement of the cavernous sinus was found in 12% of patients with JVR and 100% of patients with cavernous DAVF. Increased signal intensity in the ipsilateral jugular vein on T2-weighted imaging was found in 73% of JVR patients and 4% of cavernous DAVF patients. Early opacification of the cavernous sinus in the arterial phase of CE-MRA, ipsilateral jugular venous drainage in the arteriovenous phase of CE-MRA, and ipsilateral retrograde jugular venous flow on neck TOF MRA were found in 0%, 0%, and 63%, respectively, of JVR patients and in 100%, 100%, and 0%, respectively, of cavernous DAVF patients. CONCLUSION: JVR and cavernous DAVF can be differentiated from one another using MRI and MRA.

High-resolution magnetic resonance imaging reveals hidden etiologies of symptomatic vertebral arterial lesions.

BACKGROUND: Symptomatic intracranial vertebral artery (VA) disease has various clinical features and poor neurological outcomes. The disease is believed to result from atherosclerotic stenosis, occlusion, or spontaneous VA dissection. The underlying histopathology of symptomatic intracranial VA disease has only been studied at postmortem, and no in vivo imaging investigation has been conducted despite the increased sophistication of imaging techniques. METHODS: The authors performed high-resolution magnetic resonance imaging (HR-MRI) of intracranial vertebral arteries in 9 patients, suspected of a VA pathology by magnetic resonance imaging (MRI), magnetic resonance angiography, and digital subtraction angiography. RESULTS: HR-MRI allowed the authors to determine the following: (1) atherosclerotic plaque is composed of a large lipid core with intraplaque hemorrhage and calcification, (2) nonstenotic atherosclerosis exhibits diffuse vessel wall thickening and plaque protruding toward perforating arteries, and (3) spontaneous VA dissection exhibits large intramural hematoma in a false lumen with complete occlusion of the true lumen. In addition, VA hypoplasia was easily differentiated from atherosclerotic stenosis, by direct visualization of a narrow lumen diameter without arterial wall thickening. Furthermore, etiologic diagnoses based on classical MRI, angiography, and digital subtraction angiography were changed in 3 patients after HR-MRI. Additional information on plaque stability, indicating the possibility of unstable plaque, was found in 4 patients. CONCLUSIONS: The application of HR-MRI in stroke patients with VA pathologies enabled the authors to determine the underlying pathophysiologies. These findings could be used to improve risk stratification and treatment decision making in symptomatic intracranial VA disease.

Ventral Anterior Cingulate Atrophy as a Predisposing Factor for Transient Global Amnesia.

Background and Purpose: This study aimed to evaluate the brain magnetic resonance imaging (MRI) of patients with acute transient global amnesia (TGA) using volumetric analysis to verify whether the brains of TGA patients have pre-existing structural abnormalities. Methods: We evaluated the brain MRI data from 87 TGA patients and 20 age- and sex-matched control subjects. We included brain MRIs obtained from TGA patients within 72 hours of symptom onset to verify the pre-existence of structural change. For voxel-based morphometric analyses, statistical parametric mapping was employed to analyze the structural differences between patients with TGA and control subjects. Results: TGA patients exhibited significant volume reductions in the bilateral ventral anterior cingulate cortices (corrected p<0.05). Conclusions: TGA patients might have pre-existing structural changes in bilateral ventral anterior cingulate cortices prior to TGA attacks.

Prediction of treatment response after stereotactic radiosurgery of brain metastasis using deep learning and radiomics on longitudinal MRI data.

We developed artificial intelligence models to predict the brain metastasis (BM) treatment response after stereotactic radiosurgery (SRS) using longitudinal magnetic resonance imaging (MRI) data and evaluated prediction accuracy changes according to the number of sequential MRI scans. We included four sequential MRI scans for 194 patients with BM and 369 target lesions for the Developmental dataset. The data were randomly split (8:2 ratio) for training and testing. For external validation, 172 MRI scans from 43 patients with BM and 62 target lesions were additionally enrolled. The maximum axial diameter (Dmax), radiomics, and deep learning (DL) models were generated for comparison. We evaluated the simple convolutional neural network (CNN) model and a gated recurrent unit (Conv-GRU)-based CNN model in the DL arm. The Conv-GRU model performed superior to the simple CNN models. For both datasets, the area under the curve (AUC) was significantly higher for the two-dimensional (2D) Conv-GRU model than for the 3D Conv-GRU, Dmax, and radiomics models. The accuracy of the 2D Conv-GRU model increased with the number of follow-up studies. In conclusion, using longitudinal MRI data, the 2D Conv-GRU model outperformed all other models in predicting the treatment response after SRS of BM.

Seizures during the management of high-grade gliomas: clinical relevance to disease progression.

This study was performed to evaluate the incidence of seizures with its implications on disease progression and the diagnostic value of post-ictal magnetic resonance images (MRI) during the management of high-grade gliomas (HGGs). A total of 406 consecutive patients with newly diagnosed HGGs were retrospectively reviewed. The incidence of seizures during the management was investigated. In patients who experienced a seizure, the causality between seizures and disease progression was assessed by pre-ictal, post-ictal (<1 month), and follow-up (<3 months) MRI. After a median follow-up of 17.4 months (range 0.1-88.3), seizures developed in 127 patients (31 %). Of the 127 patients, radiological progression at the post-ictal MRI was found in 83 patients (65 %) and the follow-up MRI confirmed progression in 79 patients (62 %). Four other patients (3 %) were shown to be progression-free. Among those without radiological progression at the post-ictal MRI, the follow-up MRI confirmed progression-free in 31 patients (24 %); however, 13 patients (10 %) revealed eventual progression. In the patients with a seizure, absence of preoperative seizures (p = 0.003), <95 % tumor resection (p = 0.001), and pre-ictal Karnofsky Performance Scale score ≤ 70 (p = 0.025) were significantly associated with disease progression. During the management of HGG, 31 % of patients experienced seizures; of these patients, 72 % harbored progressive disease. The post-ictal MRI is useful for detecting disease progression; however, there are pitfalls. Clinical settings should be considered together for diagnosing disease progression in patients with seizures.

Brainstem pathways for horizontal eye movement: pathologic correlation with MR imaging.

Horizontal eye movements are conducted by the medial rectus and the lateral rectus muscles, which are innervated by the oculomotor nerve (cranial nerve III) and the abducens nerve (cranial nerve VI), respectively. The oculomotor and the abducens nuclei are interconnected by a tract in the brainstem named the medial longitudinal fasciculus (MLF). Through the MLF, the actions of the oculomotor and the abducens nuclei are coordinated, generating conjugate horizontal eye movements. The disorders of horizontal eye movement that are caused by brainstem lesions are classified into three groups: (a) lateral gaze palsy, (b) internuclear ophthalmoplegia, and (c) one-and-a-half syndrome. Lateral gaze palsy is caused by a lesion involving the paramedian pontine reticular formation (PPRF) or the abducens nucleus. Internuclear ophthalmoplegia occurs as a result of a lesion involving the MLF. One-and-a-half syndrome is a combination of lateral gaze palsy and internuclear ophthalmoplegia and is caused by a lesion involving both (a) the ipsilateral PPRF or the ipsilateral abducens nucleus and (b) the ipsilateral MLF. The pathologic lesions depicted on magnetic resonance images were topographically well correlated with the brainstem pathways and each type of horizontal eye movement disorder. Most of the lesions were tiny acute infarctions and were found in the most posterior region of the pons, which corresponded to the location of the brainstem pathways. Therefore, awareness of the brainstem pathways controlling horizontal eye movement is important to avoid missing a small pontine lesion.

Glymphatic function assessment in Parkinson's disease using diffusion tensor image analysis along the perivascular space.

INTRODUCTION: Glymphatic dysfunction can contribute to α-synucleinopathies. We examined glymphatic function in idiopathic Parkinson's disease (PD) utilizing Diffusion Tensor Image Analysis aLong the Perivascular Space (DTI-ALPS). METHODS: This study enrolled consecutive patients diagnosed with de novo PD between June 2017 and March 2019 who underwent brain DTI with concurrent 123I-2ß-carbomethoxy-3ß-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane (123I-FP-CIT) SPECT, and age- and sex-matched controls. From DTI-ALPS, the ALPS-index was calculated as a ratio of diffusivities along the x-axis in the region of neural fibers passing vertically to the diffusivities perpendicular to them, which reflected perivascular water motion at the lateral ventricular body level. The ALPS-index of the PD and control groups was compared using Student's t-test; its correlations with clinical scores for motor and cognition (UPDRS-III, MMSE, and MoCA) and striatal dopamine transporter uptake measured by 123I-FP-CIT specific binding ratios (SBRs) were examined using a correlation coefficient. RESULTS: In all, 54 patients in the de novo PD group (31 women, 23 men; mean age, 68.9 ± 9.4 years) and 54 in the control group (mean age, 69.0 ± 10.5 years) were included. The ALPS-index was lower in the PD group than in the controls (1.51 ± 0.22 versus 1.66 ± 0.20; P < 0.001). In the PD group, the ALPS-index negatively correlated with the UPDRS-III score (r = -0.526), and positively correlated with the MMSE (r = 0.377) and MoCA scores (r = 0.382) (all, P < 0.05). No correlation was observed between the ALPS-index and striatal 123I-FP-CIT SBRs (P > 0.05). CONCLUSIONS: DTI-ALPS can reveal glymphatic dysfunction in patients with PD, whose severity correlated with motor and cognitive dysfunction, but not striatal dopamine transporter uptake.

A Nationwide Web-Based Survey of Neuroradiologists' Perceptions of Artificial Intelligence Software for Neuro-Applications in Korea.

OBJECTIVE: We aimed to investigate current expectations and clinical adoption of artificial intelligence (AI) software among neuroradiologists in Korea. MATERIALS AND METHODS: In April 2022, a 30-item online survey was conducted by neuroradiologists from the Korean Society of Neuroradiology (KSNR) to assess current user experiences, perceptions, attitudes, and future expectations regarding AI for neuro-applications. Respondents with experience in AI software were further investigated in terms of the number and type of software used, period of use, clinical usefulness, and future scope. Results were compared between respondents with and without experience with AI software through multivariable logistic regression and mediation analyses. RESULTS: The survey was completed by 73 respondents, accounting for 21.9% (73/334) of the KSNR members; 72.6% (53/73) were familiar with AI and 58.9% (43/73) had used AI software, with approximately 86% (37/43) using 1-3 AI software programs and 51.2% (22/43) having up to one year of experience with AI software. Among AI software types, brain volumetry software was the most common (62.8% [27/43]). Although 52.1% (38/73) assumed that AI is currently useful in practice, 86.3% (63/73) expected it to be useful for clinical practice within 10 years. The main expected benefits were reducing the time spent on repetitive tasks (91.8% [67/73]) and improving reading accuracy and reducing errors (72.6% [53/73]). Those who experienced AI software were more familiar with AI (adjusted odds ratio, 7.1 [95% confidence interval, 1.81-27.81]; P = 0.005). More than half of the respondents with AI software experience (55.8% [24/43]) agreed that AI should be included in training curriculums, while almost all (95.3% [41/43]) believed that radiologists should coordinate to improve its performance. CONCLUSION: A majority of respondents experienced AI software and showed a proactive attitude toward adopting AI in clinical practice, suggesting that AI should be incorporated into training and active participation in AI development should be encouraged.

Primary Intracranial Ewing Sarcoma With EWSR1-FLI1 Gene Translocation Mimicking a Meningioma and a Multidisciplinary Therapeutic Approach: A Case Report and Systematic Review of Literatures.

Ewing sarcoma and peripheral primitive neuroectodermal tumor (ES/pPNET) is an undifferentiated malignant tumor that is most prevalent in children and young adults and often radiologically mimics a meningioma. A 38-year-old female patient visited our hospital with complaints of right-sided tinnitus, right hemiparesis, and imbalance. She underwent preoperative imaging and was subsequently diagnosed as having a meningioma on the petrous ridge. After partial resection, EWSR1-FLI1 gene fusion was confirmed, and she was diagnosed with ES/pPNET. The tumor was successfully treated using a multidisciplinary approach of adjuvant chemo- and radiotherapy. This case is noteworthy because it is an extremely rare case of an intracranial ES/pPNET, and it is worth sharing our clinical experience that the tumor was successfully treated through a multidisciplinary therapeutic approach even though complete resection was not achieved.

Lesion detectability on diffusion-weighted imaging in transient global amnesia: the influence of imaging timing and magnetic field strength.

INTRODUCTION: Transient global amnesia (TGA) is a benign disease with a sudden-onset, transient memory disturbance. Characteristic punctate high-signal intensity lesions in the hippocampus on diffusion-weighted imaging (DWI) have been reported in variable frequencies. We investigated the influence of the timing of DWI and the magnetic field strength on the lesion detectability in TGA. METHODS: Seventy-three patients diagnosed with TGA underwent DWI within 24 h after the symptom onset and again on day 3 at either 1.5 (n = 31) or 3 T (n = 42). The patients were divided into three subgroups according to the time lapse after the symptom onset to the first DWI (0-6 h, 6-12 h, and 12-24 h). RESULTS: The detection rate of the lesions during the first 24 h rose statistically significantly with increased time lapse after the symptom onset (34% in 0-6 h, 62% in 6-12 h, and 67% in 12-24 h). It increased up to 75% on day 3. The detection rate was higher at 3 T than at 1.5 T in all time points (41% vs. 27% in 0-6 h, 70% vs. 44% in 6-12 h, 80% vs. 57% in 12-24 h, and 86% vs. 61% on day 3), but the statistical significance was achieved only on day 3. CONCLUSION: Awareness of the different lesion detectability on DWI according to the time lapse after the symptom onset can help in diagnosing the patients with suspected TGA. High field strength is another important factor to increase the lesion detectability on DWI.