Practical aspects of functional mri in clinical examinations / Aspectos práticos de rm funcional em exames clínicos / Aspectos prácticos de la rm funcional en los exámenes clínicos

The eloquent cerebral cortices are involved in movement, sensation, speech, vision, and higher cortical functions. Functional magnetic resonance imaging (fMRI) allows the evaluation of brain function, aiding in neurosurgical planning by mapping eloquent cortical areas. Considering the high cost of the hardware involved, the purpose of this work is to present a more affordable, in-house alternative for these studies that can provide adequate results in a clinical setting. We also present some practical information on how to perform these exams. We describe an affordable in-house hardware solution used by an imaging center, and examples of fMRI paradigms used to evaluate motor and language tasks. The fMRI studies show robust activations in eloquent areas consistent with the tasks performed on the exam. Images of post-processed studies illustrate clinical cases. The fMRI have well-established applications, mapping eloquent cortical areas in patients with brain lesions. In the case of surgical planning, it allows the surgeon to maximize the resection area while minimizing sequelae. More affordable hardware can reduce the cost of these exams, making them more accessible to the general public.

O córtex cerebral eloquente está envolvido nas atividades motora, sensação, fala, visão e funções corticais superiores. A ressonância magnética funcional (RMf) permite a avaliação da função cerebral, ajudando no planejamento neurocirúrgico através do mapeamento de áreas corticais eloquentes. Considerando o elevado custo do hardware envolvido, o objetivo deste trabalho é apresentar uma alternativa mais acessível para estes estudos, que possa fornecer resultados adequados em um ambiente clínico. Também apresentamos algumas informações práticas sobre a realização destes exames. Descrevemos uma solução de hardware acessível utilizada por um centro de imagens, e exemplos de paradigmas de RMf usados para avaliar tarefas motoras e relacionadas à fala. Os estudos de RMf mostram ativações em áreas eloquentes, consistentes com as tarefas realizadas no exame com imagens de estudos pós-processados ilustrando casos clínicos. A RMf tem aplicações bem estabelecidas, mapeando áreas corticais eloquentes em pacientes com lesões cerebrais. No caso do planejamento cirúrgico, permite que o cirurgião maximize a área de ressecção enquanto minimiza potenciais sequelas. Equipamentos mais acessíveis podem reduzir o custo destes exames, podendo aumentar a disponibilização ao público em geral.

La corteza cerebral elocuente está implicada en las actividades motoras, la sensibilidad, el habla, la visión y las funciones corticales superiores. La resonancia magnética funcional (RMf) permite la evaluación de la función cerebral, ayudando en la planificación neuroquirúrgica mediante el mapeo de las áreas corticales elocuentes. Teniendo en cuenta el elevado coste del hardware implicado, el objetivo de este artículo es presentar una alternativa más asequible para estos estudios que pueda proporcionar resultados adecuados en un entorno clínico. También presentamos información práctica sobre cómo realizar estos exámenes. Describimos una solución de hardware asequible utilizada por un centro de diagnóstico por imagen, y ejemplos de paradigmas de RMf utilizados para evaluar tareas motoras y relacionadas con el habla. Los estudios de RMf muestran activaciones en áreas elocuentes, coherentes con las tareas realizadas en el examen, con imágenes de estudios postprocesados que ilustran casos clínicos. La RMf tiene aplicaciones bien establecidas en el mapeo de áreas corticales elocuentes en pacientes con lesiones cerebrales. En el caso de la planificación quirúrgica, permite al cirujano maximizar el área de resección minimizando las posibles secuelas. Un equipo más asequible puede reducir el coste de estas exploraciones, aumentando potencialmente su disponibilidad para el público en general.

Research Development in Patients with Multiple Sclerosis by Focus on MRI / 罕见病研究

Multiple sclerosis (MS) is an autoimmune inflammatory demyelinating disease of the central nervous system whose clinical manifestations and diagnostic criteria are non-specific and absence of golden criteria when diagnosing. Magnetic resonance imaging (MRI) can not only observe the focal lesions of demyelination, but also evaluate microstructural damages and iron deposition in the white/gray matter in MS patients by applying various developing sequences. MRIs play an irreplaceable role in revealing pathological evolution, prognosis and monitoring after treatment of MS patients. This paper reviewed the clinical value and application of MRIs for the MS patients in recent years.

Changes in default network topology properties of brain function in maintenance dialysis patients with end-stage renal disease with cognitive impairment / 中华行为医学与脑科学杂志

Objective:To investigate the relationship between the changes of default network topology properties of brain function and cognitive function in patients with end-stage renal disease (ESRD).Methods:A total of 31 patients with ESRD were enrolled in the Department of Nephrology, Changzhou Second Hospital Affiliated to Nanjing Medical University from January 2019 to December 2020, and 18 healthy persons were included in the same period as the control group.The cognitive function was evaluated with the Montreal cognitive assessment (MoCA) and trail making tests, and then the subjects were examined by resting-state functional magnetic resonance imaging (rs-fMRI). After preprocessing, the brain functional network was constructed and the topology properities of the network were calculated.The SPSS 20.0 software was used for statistical analysis.Independent sample t-test, chi square test and Pearson correlation analysis were used for data statistics. Results:(1) The score of MoCA in the ESRD group(23.37±1.77) was significantly lower than that in the healthy control group(27.94±1.13)( t=9.537, P<0.001). (2) The levels of Eglobal, Elocal, Cp and Sigma in ESRD group ((0.129±0.025), (0.148±0.040), (0.188±0.046), (1.593±0.650)) were significantly lower than those in healthy control group ((0.160±0.040), (0.212±0.024), (0.276±0.049), (2.004±0.864))( t=3.591, 7.474, 7.058, 2.034, all P<0.05). The Lp value of the ESRD group (8.131±1.905) was significantly higher than that of the control group (6.777±2.150)( t=2.583, P< 0.05). The node efficiency values of bilateral dorsolateral superior frontal gyrus, left middle frontal gyrus, bilateral posterior cingulate gyrus, right hippocampus, left superior marginal gyrus, bilateral angular gyrus and bilateral cuneate anterior lobe in ESRD group ((0.133±0.071), (0.201±0.047), (0.211±0.106), (0.175±0.066), (0.276±0.113), (0.122±0.146), (0.042±0.075), (0.171±0.027), (0.154±0.078), (0.240±0.095), (0.161±0.056))were lower than those in the healthy control group((0.312±0.075), (0.289±0.091), (0.277±0.132), (0.284±0.053), (0.368±0.063), (0.231±0.227), (0.120±0.162), (0.296±0.064), (0.310±0.186), (0.318±0.066), (0.286±0.103))( t=2.107-9.436, all P<0.05). (3)Pearson correlation analysis showed that the node efficiency values of bilateral posterior cingulate gyrus and right hippocampus in ESRD group were positively correlated with the score of MoCA( r=0.36, 0.49, 0.53, all P<0.05). Conclusion:The topological structure of brain functional network is abnormal in ESRD patients, which can affect the cognitive function of patients.

Progress in the comparative study of structural and functional magnetic resonance imaging of schizophrenia and obsessive-compulsive disorder / 四川精神卫生

Schizophrenia and obsessive-compulsive disorder are common disorders in clinical psychiatry， accompanied by varying degrees of painful experience and social functioning impairment， and a high prevalence rate of co-morbidities. In this paper， a review of comparative study of structural and functional magnetic resonance imaging of the two diseases is presented， so as to explore the similar and specific biological markers of them and to provide a forceful imaging basis for subsequent studies.

Test-Retest Reliability of Functional Magnetic Resonance Imaging Activation for a Vergence Eye Movement Task / 神经科学通报·英文版

Vergence eye movements are the inward and outward rotation of the eyes responsible for binocular coordination. While studies have mapped and investigated the neural substrates of vergence, it is not well understood whether vergence eye movements evoke the blood oxygen level-dependent signal reliably in separate experimental visits. The test-retest reliability of stimulus-induced vergence eye movement tasks during a functional magnetic resonance imaging (fMRI) experiment is important for future randomized clinical trials (RCTs). In this study, we established region of interest (ROI) masks for the vergence neural circuit. Twenty-seven binocularly normal young adults participated in two functional imaging sessions measured on different days on the same 3T Siemens scanner. The fMRI experiments used a block design of sustained visual fixation and rest blocks interleaved between task blocks that stimulated eight or four vergence eye movements. The test-retest reliability of task-activation was assessed using the intraclass correlation coefficient (ICC), and that of spatial extent was assessed using the Dice coefficient. Functional activation during the vergence eye movement task of eight movements compared to rest was repeatable within the primary visual cortex (ICC = 0.8), parietal eye fields (ICC = 0.6), supplementary eye field (ICC = 0.5), frontal eye fields (ICC = 0.5), and oculomotor vermis (ICC = 0.6). The results demonstrate significant test-retest reliability in the ROIs of the vergence neural substrates for functional activation magnitude and spatial extent using the stimulus protocol of a task block stimulating eight vergence eye movements compared to sustained fixation. These ROIs can be used in future longitudinal RCTs to study patient populations with vergence dysfunctions.

Alteration of low frequency fluctuation amplitude at brain-resting state in patients with chronic discogenic low back pain / 中国组织工程研究

BACKGROUND: Neuroimaging studies have shown that chronic pain could cause functional and structural alterations; however, the neural mechanism of psychosomatic symptoms caused by chronic discogenic low back pain (CDLBP) remains unclear. OBJECTIVE: To investigate the alterations of amplitude of low frequency fluctuation (ALFF) of resting spontaneous brain activity in CDLBP patients and their relationships with clinical symptoms. METHODS: Resting-state brain functional MRI scans were performed in 67 CDLBP patients (CDLBP group) and 78 age-, sex-and education level-matched healthy controls (control group). The disease course, Visual Analogue Scale score, Oswestry Disability Index and Self-rating Depression Scale score were analyzed for CDLBP patients. The average ALFF values of the two groups were calculated using DPARSF and REST software, the differences of ALFF values between the two groups were compared by independent two-sample t-test, and the relationships between the ALFF values derived from significant regions and the course of disease and clinical symptoms were analyzed. The study protocol was approved by the Ethics Committee of Second Affiliated Hospital of Xinxiang Medical University (approval No. 20150210). RESULTS AND CONCLUSION: Compared with the control group, the regions with significantly increased ALFF values in the CDLBP group included the left insular lobe, right parahippocampal gyrus, bilateral superior temporal gyrus, left inferior temporal gyrus, bilateral prefrontal lobe, left caudate nucleus and right inferior frontal gyrus (all P < 0.05, Gaussian random field (GRF) corrected). Compared with the control group, the regions with significantly decreased ALFF values in the CDLBP group included the right superior orbital frontal gyrus and right lingual gyrus (both P <0.05, GRF corrected). Correlation analysis showed that the mean ALFF values in the right inferior frontal gyrus and left caudate nucleus were positively correlated with the Visual Analogue Scale (all P < 0.05). All these findings suggest that patients with CDLBP have abnormal spontaneous brain activities in multiple brain regions, and these alterations are correlated with the degree of pain.

Structural and functional neuroimaging studies in generalized anxiety disorder: a systematic review

Objectives: Brain imaging studies carried out in patients suffering from generalized anxiety disorder (GAD) have contributed to better characterize the pathophysiological mechanisms underlying this disorder. The present study reviews the available functional and structural brain imaging evidence on GAD, and suggests further strategies for investigations in this field. Methods: A systematic literature review was performed in PubMed, PsycINFO, and Google Scholar, aiming to identify original research evaluating GAD patients with the use of structural and functional magnetic resonance imaging as well as diffusion tensor imaging. Results: The available studies have shown impairments in ventrolateral and dorsolateral prefrontal cortex, anterior cingulate, posterior parietal regions, and amygdala in both pediatric and adult GAD patients, mostly in the right hemisphere. However, the literature is often tentative, given that most studies have employed small samples and included patients with comorbidities or in current use of various medications. Finally, different methodological aspects, such as the type of imaging equipment used, also complicate the generalizability of the findings. Conclusions: Longitudinal neuroimaging studies with larger samples of both juvenile and adult GAD patients, as well as at risk individuals and unaffected relatives, should be carried out in order to shed light on the specific biological signature of GAD.

Changes in the Laterality of Functional Connectivity Associated with Tinnitus: Resting-State fMRI Study

PURPOSE: One of the suggested potential mechanisms of tinnitus is an alteration in perception in the neural auditory pathway. The aim of this study was to investigate the difference in laterality in functional connectivity between tinnitus patients and healthy controls using resting state functional MRI (rs-fMRI). MATERIALS AND METHODS: Thirty-eight chronic tinnitus subjects and 45 age-matched healthy controls were enrolled in this study. Connectivity was investigated using independent component analysis, and the laterality index map was calculated based on auditory (AN) and dorsal attention (DAN), default mode (DMN), sensorimotor, salience (SalN), and visual networks (VNs). The laterality index (LI) of tinnitus subjects was compared with that of normal controls using region-of-interest (ROI) and voxel-based methods and a two-sample unpaired t-test. Pearson correlation was conducted to assess the associations between the LI in each network and clinical variables. RESULTS: The AN and VN showed significant differences in LI between the two groups in ROI analysis (P < 0.05), and the tinnitus group had clusters with significantly decreased laterality of AN, SalN, and VN in voxel-based comparisons. The AN was positively correlated with tinnitus distress (tinnitus handicap inventory), and the SalN was negatively correlated with symptom duration (P < 0.05). CONCLUSION: The results of this study suggest that various functional networks related to psychological distress can be modified by tinnitus, and that this interrelation can present differently on the right and left sides, according to the dominance of the network.

Seed-Based Resting-State Functional MRI for Presurgical Localization of the Motor Cortex: A Task-Based Functional MRI-Determined Seed Versus an Anatomy-Determined Seed

OBJECTIVE: For localization of the motor cortex, seed-based resting-state functional MRI (rsfMRI) uses the contralateral motor cortex as a seed. However, research has shown that the location of the motor cortex could differ according to anatomical variations. The purpose of this study was to compare the results of rsfMRI using two seeds: a template seed (the anatomically expected location of the contralateral motor cortex) and a functional seed (the actual location of the contralateral motor cortex determined by task-based functional MRI [tbfMRI]). MATERIALS AND METHODS: Eight patients (4 with glioma, 3 with meningioma, and 1 with arteriovenous malformation) and 9 healthy volunteers participated. For the patients, tbfMRI was performed unilaterally to activate the healthy contralateral motor cortex. The affected ipsilateral motor cortices were mapped with rsfMRI using seed-based and independent component analysis (ICA). In the healthy volunteer group, both motor cortices were mapped with both-hands tbfMRI and rsfMRI. We compared the results between template and functional seeds, and between the seed-based analysis and ICA with visual and quantitative analysis. RESULTS: For the visual analysis, the functional seed showed significantly higher scores compared to the template seed in both the patients (p = 0.002) and healthy volunteers (p < 0.001). Although no significant difference was observed between the functional seed and ICA, the ICA results showed significantly higher scores than the template seed in both the patients (p = 0.01) and healthy volunteers (p = 0.005). In the quantitative analysis, the functional seed exhibited greater similarity to tbfMRI than the template seed and ICA. CONCLUSION: Using the contralateral motor cortex determined by tbfMRI as a seed could enhance visual delineation of the motor cortex in seed-based rsfMRI.

Multiparametric Functional Magnetic Resonance Imaging for Evaluating Renal Allograft Injury

Kidney transplantation is the treatment of choice for patients with end-stage renal disease, as it extends survival and increases quality of life in these patients. However, chronic allograft injury continues to be a major problem, and leads to eventual graft loss. Early detection of allograft injury is essential for guiding appropriate intervention to delay or prevent irreversible damage. Several advanced MRI techniques can offer some important information regarding functional changes such as perfusion, diffusion, structural complexity, as well as oxygenation and fibrosis. This review highlights the potential of multiparametric MRI for noninvasive and comprehensive assessment of renal allograft injury.

Monitoring Response to Neoadjuvant Chemotherapy of Primary Osteosarcoma Using Diffusion Kurtosis Magnetic Resonance Imaging: Initial Findings

OBJECTIVE: To determine whether diffusion kurtosis imaging (DKI) is effective in monitoring tumor response to neoadjuvant chemotherapy in patients with osteosarcoma. MATERIALS AND METHODS: Twenty-nine osteosarcoma patients (20 men and 9 women; mean age, 17.6 ± 7.8 years) who had undergone magnetic resonance imaging (MRI) and DKI before and after neoadjuvant chemotherapy were included. Tumor volume, apparent diffusion coefficient (ADC), mean diffusivity (MD), mean kurtosis (MK), and change ratio (ΔX) between pre- and post-treatment were calculated. Based on histologic response, the patients were divided into those with good response (≥ 90% necrosis, n = 12) and those with poor response (< 90% necrosis, n = 17). Several MRI parameters between the groups were compared using Student's t test. The correlation between image indexes and tumor necrosis was determined using Pearson's correlation, and diagnostic performance was compared using receiver operating characteristic curves. RESULTS: In good responders, MDpost, ADCpost, and MKpost values were significantly higher than in poor responders (p < 0.001, p < 0.001, and p = 0.042, respectively). The ΔMD and ΔADC were also significantly higher in good responders than in poor responders (p < 0.001 and p = 0.01, respectively). However, no significant difference was observed in ΔMK (p = 0.092). MDpost and ΔMD showed high correlations with tumor necrosis rate (r = 0.669 and r = 0.622, respectively), and MDpost had higher diagnostic performance than ADCpost (p = 0.037) and MKpost (p = 0.011). Similarly, ΔMD also showed higher diagnostic performance than ΔADC (p = 0.033) and ΔMK (p = 0.037). CONCLUSION: MD is a promising biomarker for monitoring tumor response to preoperative chemotherapy in patients with osteosarcoma.

MRI Evaluation of Suspected Pathologic Fracture at the Extremities from Metastasis: Diagnostic Value of Added Diffusion-Weighted Imaging

OBJECTIVE: To assess the diagnostic value of combining diffusion-weighted imaging (DWI) with conventional magnetic resonance imaging (MRI) for differentiating between pathologic and traumatic fractures at extremities from metastasis. MATERIALS AND METHODS: Institutional Review Board approved this retrospective study and informed consent was waived. This study included 49 patients each with pathologic and traumatic fractures at extremities. The patients underwent conventional MRI combined with DWI. For qualitative analysis, two radiologists (R1 and R2) independently reviewed three imaging sets with a crossover design using a 5-point scale and a 3-scale confidence level: DWI plus non-enhanced MRI (NEMR; DW set), NEMR plus contrast-enhanced fat-saturated T1-weighted imaging (CEFST1; CE set), and DWI plus NEMR plus CEFST1 (combined set). McNemar's test was used to compare the diagnostic performances among three sets and perform subgroup analyses (single vs. multiple bone abnormality, absence/presence of extra-osseous mass, and bone enhancement at fracture margin). RESULTS: Compared to the CE set, the combined set showed improved diagnostic accuracy (R1, 84.7 vs. 95.9%; R2, 91.8 vs. 95.9%, p 0.05). In cases of absent extra-osseous soft tissue mass and present fracture site enhancement, the combined set showed improved accuracy (R1, 82.9–84.4% vs. 95.6–96.3%, p < 0.05; R2, 90.2–91.1% vs. 95.1–95.6%, p < 0.05) and specificity (R1, 68.3–72.9% vs. 92.7–95.8%, p < 0.005; R2, 83.0–85.4% vs. 97.6–98.0%, p = 0.07). CONCLUSION: Combining DWI with conventional MRI improved the diagnostic accuracy and specificity while retaining sensitivity for differentiating between pathologic and traumatic fractures from metastasis at extremities.

Functional Magnetic Resonance Imaging in the Diagnosis of Locally Recurrent Prostate Cancer: Are All Pulse Sequences Helpful?

OBJECTIVE: To perform a meta-analysis to quantitatively assess functional magnetic resonance imaging (MRI) in the diagnosis of locally recurrent prostate cancer. MATERIALS AND METHODS: A comprehensive search of the PubMed, Embase, Cochrane Central Register of Controlled Trials, and Cochrane Database of Systematic Reviews was conducted from January 1, 1995 to December 31, 2016. Diagnostic accuracy was quantitatively pooled for all studies by using hierarchical logistic regression modeling, including bivariate modeling and hierarchical summary receiver operating characteristic (HSROC) curves (AUCs). The Z test was used to determine whether adding functional MRI to T2-weighted imaging (T2WI) results in significantly increased diagnostic sensitivity and specificity. RESULTS: Meta-analysis of 13 studies involving 826 patients who underwent radical prostatectomy showed a pooled sensitivity and specificity of 91%, and the AUC was 0.96. Meta-analysis of 7 studies involving 329 patients who underwent radiotherapy showed a pooled sensitivity of 80% and specificity of 81%, and the AUC was 0.88. Meta-analysis of 11 studies reporting 1669 sextant biopsies from patients who underwent radiotherapy showed a pooled sensitivity of 54% and specificity of 91%, and the AUC was 0.85. Sensitivity after radiotherapy was significantly higher when diffusion-weighted MRI data were combined with T2WI than when only T2WI results were used. This was true when meta-analysis was performed on a per-patient basis (p = 0.027) or per sextant biopsy (p = 0.046). A similar result was found when ¹H-magnetic resonance spectroscopy (¹H-MRS) data were combined with T2WI and sextant biopsy was the unit of analysis (p = 0.036). CONCLUSION: Functional MRI data may not strengthen the ability of T2WI to detect locally recurrent prostate cancer in patients who have undergone radical prostatectomy. By contrast, diffusion-weight MRI and ¹H-MRS data may improve the sensitivity of T2WI for patients who have undergone radiotherapy.

Cortical Representation of Pain and Touch: Evidence from Combined Functional Neuroimaging and Electrophysiology in Non-human Primates / 神经科学通报·英文版

Human functional MRI studies in acute and various chronic pain conditions have revolutionized how we view pain, and have led to a new theory that complex multi-dimensional pain experience (sensory-discriminative, affective/motivational, and cognitive) is represented by concurrent activity in widely-distributed brain regions (termed a network or pain matrix). Despite these breakthrough discoveries, the specific functions proposed for these regions remain elusive, because detailed electrophysiological characterizations of these regions in the primate brain are lacking. To fill in this knowledge gap, we have studied the cortical areas around the central and lateral sulci of the non-human primate brain with combined submillimeter resolution functional imaging (optical imaging and fMRI) and intracranial electrophysiological recording. In this mini-review, I summarize and present data showing that the cortical circuitry engaged in nociceptive processing is much more complex than previously recognized. Electrophysiological evidence supports the engagement of a distinct nociceptive-processing network within SI (i.e., areas 3a, 3b, 1 and 2), SII, and other areas along the lateral sulcus. Deafferentation caused by spinal cord injury profoundly alters the relationships between fMRI and electrophysiological signals. This finding has significant implications for using fMRI to study chronic pain conditions involving deafferentation in humans.

Functional connectivity of the fronto-striatal circuitry in patients with bulimia nervosa based on resting-state fMRI / 中华行为医学与脑科学杂志

Objective To explore the functional connectivity (FC) of the fronto-striatal circuitry in patients with bulimia nervosa (BN) based on the resting-state fMRI and its correlation with the inhibitory function.Methods 27 medication-naive female patients with BN and 27 age-and education-matched female healthy control subjects were included in the study.All the subjects performed a stop signal task (SST) and underwent the resting-state fMRI scan,separately.The FC between striatal subregions and the frontal cortex was analyzed.Results Compared with healthy controls,FC between the right ventral rostral putamen (VRP) and the right supplementary motor areas (SMA) decreased (MNI coordinate:x =3,y =-15,z =51,K =27) in patients with BN.And the FC was also decreased between the right VRP and premotor area(PM) (MNI coordinate:x =27,y =0,z =57,K =44).FC between bilateral dorsal caudal putamen (DCP) (MNI coordinate:x=21,y=-6,z=48,K=43) and the right PM(MNI coordinate:x=21,y=-12,z=57,K=24) was decreased in patients with BN (P＜0.05,Alphasim corrected,voxel P＜0.005,clusters ≥ 20 voxels).FC between the right VRP and right SMA was negatively correlated with the stop signal reaction time (SSRT) in patients with BN (r=-0.595,P=0.004).The FC between right DCP and right PM was positively correlated with the impulsivity regulation subscale scores of the Eating Disorder Inventory-Ⅱ in patients with BN(r=0.483,P=0.023).Conclusion There is disrupted FC between the striatum and motor cortex in medication-naive female patients with BN based on resting-state fMRI,which may be related to impaired inhibitory control in patients with BN.

Brain Regional Homogeneity Changes in Cirrhotic Patients with or without Hepatic Encephalopathy Revealed by Multi-Frequency Bands Analysis Based on Resting-State Functional MRI

OBJECTIVE: To investigate brain regional homogeneity (ReHo) changes of multiple sub-frequency bands in cirrhotic patients with or without hepatic encephalopathy using resting-state functional MRI. MATERIALS AND METHODS: This study recruited 46 cirrhotic patients without clinical hepatic encephalopathy (noHE), 38 cirrhotic patients with clinical hepatic encephalopathy (HE), and 37 healthy volunteers. ReHo differences were analyzed in slow-5 (0.010−0.027 Hz), slow-4 (0.027−0.073 Hz), and slow-3 (0.073−0.198 Hz) bands. Routine analysis of (0.010−0.080 Hz) band was used as a benchmark. Associations of abnormal ReHo values in each frequency band with neuropsychological scores and blood ammonia level were analyzed. Pattern classification analyses were conducted to determine whether ReHo differences in each band could differentiate the three groups of subjects (patients with or without hepatic encephalopathy and healthy controls). RESULTS: Compared to routine analysis, more differences between HE and noHE were observed in slow-5 and slow-4 bands (p 12, overall corrected p < 0.05). Sub-frequency band analysis also showed that ReHo abnormalities were frequency-dependent (overall corrected p < 0.05). In addition, ReHo abnormalities in each sub-band were correlated with blood ammonia level and neuropsychological scores, especially in the left inferior parietal lobe (overall corrected p < 0.05 for all frequency bands). Pattern classification analysis demonstrated that ReHo differences in lower slow-5 and slow-4 bands (both p < 0.05) and higher slow-3 band could differentiate the three groups (p < 0.05). Compared to routine analysis, ReHo features in slow-4 band obtained better classification accuracy (89%). CONCLUSION: Cirrhotic patients showed frequency-dependent changes in ReHo. Sub-frequency band analysis is important for understanding HE and clinical monitoring.

Hallazgos radiológicos en sistema nervioso central (SNC) del síndrome de MELAS: reporte de caso / Radiological findings of MELAS syndrome in central nervous system (CNS): case report

RESUMEN Presentamos el caso clínico de una paciente adulta joven con episodios recurrentes sugestivos de ataque cerebrovascular, con cambios radiológicos típicos de enfermedad de MELAS con confirmación genética de mutación en el gen A3243G.

SUMMARY A clinical case of a young adult patient with recurrent episodes suggestive of stroke, with typical radiological changes of MELAS disease with genetic confirmation of mutation in A3243G gene.

Improved Diagnostic Accuracy of Alzheimer's Disease by Combining Regional Cortical Thickness and Default Mode Network Functional Connectivity: Validated in the Alzheimer's Disease Neuroimaging Initiative Set

OBJECTIVE: To identify potential imaging biomarkers of Alzheimer's disease by combining brain cortical thickness (CThk) and functional connectivity and to validate this model's diagnostic accuracy in a validation set. MATERIALS AND METHODS: Data from 98 subjects was retrospectively reviewed, including a study set (n = 63) and a validation set from the Alzheimer's Disease Neuroimaging Initiative (n = 35). From each subject, data for CThk and functional connectivity of the default mode network was extracted from structural T1-weighted and resting-state functional magnetic resonance imaging. Cortical regions with significant differences between patients and healthy controls in the correlation of CThk and functional connectivity were identified in the study set. The diagnostic accuracy of functional connectivity measures combined with CThk in the identified regions was evaluated against that in the medial temporal lobes using the validation set and application of a support vector machine. RESULTS: Group-wise differences in the correlation of CThk and default mode network functional connectivity were identified in the superior temporal (p < 0.001) and supramarginal gyrus (p = 0.007) of the left cerebral hemisphere. Default mode network functional connectivity combined with the CThk of those two regions were more accurate than that combined with the CThk of both medial temporal lobes (91.7% vs. 75%). CONCLUSION: Combining functional information with CThk of the superior temporal and supramarginal gyri in the left cerebral hemisphere improves diagnostic accuracy, making it a potential imaging biomarker for Alzheimer's disease.

Temporal Evolution of a Chronic Expanding Organizing Hematoma on MRI, Including Functional MR Imaging Techniques: a Case Report

Chronic expanding organizing hematoma (CEH) occasionally mimics a soft tissue tumor on MRI, which becomes more problematic in patients with a history of surgical resection for musculoskeletal malignancy. Herein, we present a case of CEH which we were able to differentiate from recurrent tumor through MRI follow-up, including diffusion-weighted imaging (DWI) and dynamic contrast enhanced (DCE) imaging. A 66-year-old male visited our institution under suspicion of recurrent leiomyosarcoma of the thigh, 19 months after surgery and radiation therapy. Due to inconclusive results, three US-guided biopsies and 6 MRI examinations were performed over 2 years. In the end, we could diagnose a CEH using conventional and functional MRI techniques, and it was histopathologically confirmed after surgical resection. A CEH may occur remotely after an initiating event, and it may persist and expand over several years. Functional MR sequences, in addition to conventional sequences, are helpful in differentiating CEH from malignant neoplasms.

Functional Magnetic Resonance Imaging with Arterial Spin Labeling: Techniques and Potential Clinical and Research Applications

PURPOSE: To describe technical methods for functional magnetic resonance imaging (fMRI) study with arterial spin labeling (ASL) compared to blood oxygenation level-dependent (BOLD) technique and discuss the potential of ASL for research and clinical practice. MATERIALS AND METHODS: Task-based (n = 1) and resting-state fMRI (rs-fMRI) (n = 20) were performed using ASL and BOLD techniques. Results of both techniques were compared. RESULTS: For task-based fMRI with finger-tapping, the primary motor cortex of the contralateral frontal lobe and the ipsilateral cerebellum were activated by both BOLD and ASL fMRI. For rs-fMRI of sensorimotor network, functional connectivity showed similar results between BOLD and ASL. CONCLUSION: ASL technique has potential application in clinical and research fields because all brain perfusion imaging, CBF measurement, and rs-fMRI study can be performed in a single acquisition.