Influence of scan duration on dynamic contrast -enhanced magnetic resonance imaging pharmacokinetic parameters for brain lesions.

OBJECTIVE: Gadolinium-based contrast agent needs time to leak into the extravascular-extracellular space, leak back into the vascular space, and reach an equilibrium state. For this reason, acquisition times of <10 min may cause inaccurate estimation of pharmacokinetic parameters. Since no studies have been conducted on the influence of long scan times on DCE-MRI parameters in brain tumors, the aim of this study is to investigate the variation of DCE-MRI-derived kinetic parameters as a function of acquisition time, from 5 to 10 min in brain tumors. MATERIALS AND METHODS: Fifty-two patients with histologically confirmed brain tumors were enrolled in this retrospective study, and examination at 3 T, DCE-MRI, with scan duration of 10 min, was used for retrospective generation of 6 sets of quantitative DCE-MRI maps (Ktrans, Ve and Kep) from 5 to 10 min. Features were extracted from the DCE-MRI maps in contrast enhancement (CE) volumes. Kruskal-Wallis with post-hoc correction and coefficient of variation (CoV) were used as statistical test to compare DCE-MRI maps obtained from 6 data sets. SIGNIFICANCE: p < 0.05. RESULTS: No differences in Ktrans features in CE volumes between different scan durations. Ve, Kep features in CE volumes were influenced by different data length. The highest number of significantly different Ve and Kep features in CE volumes were between 5 min and 10 min (p < 0.013), 5 min and 9 min (p < 0.044), 6 min and 10 min (p < 0.040). CoV of Kep was reduced from 5 min to 10 min, going from highly variable (CoV = 0.70) to mildly variable (CoV = 0.42). CONCLUSION: Kep and Ve were time-dependent in brain tumors, so a longer scan time is needed to obtain reliable parameter values. Ktrans was found to be time-independent, as it remains the same in all 6 acquisition times and is the only reliable parameter with short acquisition times.

MRI and Clinical Biomarkers Overlap between Glaucoma and Alzheimer's Disease.

Glaucoma is the leading cause of blindness worldwide. It is classically associated with structural and functional changes in the optic nerve head and retinal nerve fiber layer, but the damage is not limited to the eye. The involvement of the central visual pathways and disruption of brain network organization have been reported using advanced neuroimaging techniques. The brain structural changes at the level of the areas implied in processing visual information could justify the discrepancy between signs and symptoms and underlie the analogy of this disease with neurodegenerative dementias, such as Alzheimer's disease, and with the complex group of pathologies commonly referred to as "disconnection syndromes." This review aims to summarize the current state of the art on the use of advanced neuroimaging techniques in glaucoma and Alzheimer's disease, highlighting the emerging biomarkers shared by both diseases.

Multishell diffusion MRI reveals whole-brain white matter changes in HIV.

Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) have been previously used to explore white matter related to human immunodeficiency virus (HIV) infection. While DTI and DKI suffer from low specificity, the Combined Hindered and Restricted Model of Diffusion (CHARMED) provides additional microstructural specificity. We used these three models to evaluate microstructural differences between 35 HIV-positive patients without neurological impairment and 20 healthy controls who underwent diffusion-weighted imaging using three b-values. While significant group effects were found in all diffusion metrics, CHARMED and DKI analyses uncovered wider involvement (80% vs. 20%) of all white matter tracts in HIV infection compared with DTI. In restricted fraction (FR) analysis, we found significant differences in the left corticospinal tract, middle cerebellar peduncle, right inferior cerebellar peduncle, right corticospinal tract, splenium of the corpus callosum, left superior cerebellar peduncle, left superior cerebellar peduncle, pontine crossing tract, left posterior limb of the internal capsule, and left/right medial lemniscus. These are involved in language, motor, equilibrium, behavior, and proprioception, supporting the functional integration that is frequently impaired in HIV-positivity. Additionally, we employed a machine learning algorithm (XGBoost) to discriminate HIV-positive patients from healthy controls using DTI and CHARMED metrics on an ROIwise basis, and unique contributions to this discrimination were examined using Shapley Explanation values. The CHARMED and DKI estimates produced the best performance. Our results suggest that biophysical multishell imaging, combining additional sensitivity and built-in specificity, provides further information about the brain microstructural changes in multimodal areas involved in attentive, emotional and memory networks often impaired in HIV patients.

Triple gallbladder: radiological review.

Triple gallbladder represents a rare congenital anatomical abnormality that can be a diagnostic challenge in reason to its rarity and consequential difficulties with diagnosis and identification. A systematic review of all published literature between 1958 and 2022 was performed. We identified 20 previous studies that provided 20 cases of triple gallbladder; our case was also included in the analysis, making a total of 21 patients. All patients underwent on diagnostic imaging examinations. After 1985, 9 patients underwent US examination which allowed prompt recognition of triple gallbladder in 2 patients only. CT was performed in 3 patients and allowed the correct diagnosis in a case. In 4 patients, was performed MRCP which allowed the correct diagnosis of triple gallbladder in all patients. Preoperative imaging allows the recognition of triple gallbladder in 9 of 21 patients (43%); in 12 patients (57%) the diagnosis was intraoperative. On patients considered, 16/21 underwent cholecystectomy. In 15 cases, the excised gallbladders were submitted for histopathological characterization with detection of metaplasia of the mucosa in 3 patients, while papillary adenocarcinoma was found in one. Imaging plays a key role in the identification of the anatomical variants of gallbladder, especially triple gallbladder, as modern imaging techniques allow a detailed assessment of the course of the biliary tract for a correct preoperative diagnosis. It is also crucial to be aware of the association between this condition and the metaplasia phenomena with the development of adenocarcinoma, as this may influence the patient's course of treatment.

Sex hormones differentially contribute to Parkinson disease in males: A multimodal biomarker study.

BACKGROUND AND PURPOSE: Parkinson disease (PD) presents relevant sex-related differences in epidemiology, pathophysiology, and clinical features, with males being more vulnerable to the disease. Sex hormones might have a role, as the experimental models suggest; however, human-based evidence is scarce. Here, we integrated multimodal biomarkers to investigate the relationships between circulating sex hormones and clinical-pathological features in male PD patients. METHODS: A cohort of 63 male PD patients underwent comprehensive clinical evaluation of motor and nonmotor disturbances; measurement of estradiol, testosterone, follicle-stimulating hormone (FSH), and luteinizing hormone (LH) blood levels; and cerebrospinal fluid (CSF) assay of total α-synuclein, amyloid-ß-42, amyloid-ß-40, total tau, and phosphorylated-181 tau levels. A subgroup of 47 PD patients underwent brain volumetry by 3-T magnetic resonance imaging for further correlations. A control group of 56 age-matched individuals was enrolled for comparative analyses. RESULTS: Male PD patients had higher estradiol and testosterone levels than controls. Estradiol had independent inverse associations with Movement Disorder Society-Unified Parkinson's Disease Rating Scale Part 3 score and disease duration; it was also lower in nonfluctuating patients. Testosterone had inverse independent correlations with CSF α-synuclein and right globus pallidus volume. FSH and LH had age-dependent correlations with cognitive impairment and CSF amyloid-ß-42/amyloid-ß-40 ratio. CONCLUSIONS: The study suggested that sex hormones could differentially contribute to clinical-pathological features of PD in male patients. Whereas estradiol might have a protective role in motor impairment, testosterone might be involved in male vulnerability to PD neuropathology. Gonadotropins instead might mediate age-dependent phenomena of amyloidopathy and cognitive decline.

PVA-Microbubbles as a Radioembolization Platform: Formulation and the In Vitro Proof of Concept.

This proof-of-concept study lays the foundations for the development of a delivery strategy for radioactive lanthanides, such as Yttrium-90, against recurrent glioblastoma. Our appealing hypothesis is that by taking advantage of the combination of biocompatible polyvinyl alcohol (PVA) microbubbles (MBs) and endovascular radiopharmaceutical infusion, a minimally invasive selective radioembolization can be achieved, which can lead to personalized treatments limiting off-target toxicities for the normal brain. The results show the successful formulation strategy that turns the ultrasound contrast PVA-shelled microbubbles into a microdevice, exhibiting good loading efficiency of Yttrium cargo by complexation with a bifunctional chelator. The selective targeting of Yttrium-loaded MBs on the glioblastoma-associated tumor endothelial cells can be unlocked by the biorecognition between the overexpressed αVß3 integrin and the ligand Cyclo(Arg-Gly-Asp-D-Phe-Lys) at the PVA microbubble surface. Hence, we show the suitability of PVA MBs as selective Y-microdevices for in situ injection via the smallest (i.e., 1.2F) neurointerventional microcatheter available on the market and the accumulation of PVA MBs on the HUVEC cell line model of integrin overexpression, thereby providing ~6 × 10-15 moles of Y90 per HUVEC cell. We further discuss the potential impact of using such versatile PVA MBs as a new therapeutic chance for treating glioblastoma multiforme recurrence.

Influence of sagittal pelvic attitude on gait pattern in normally developed people and interactions with neurological pathologies: A pilot study.

Background: Gait Analysis of healthy people, imitating pathological conditions while walking, has increased our understanding of biomechanical factors. The influence of the pelvis as a biomechanical constraint during gait is not specifically studied. How could mimicking a pelvic attitude influence the dynamic mechanical interaction of the body segments? We proposed an investigation of the pelvic attitude role on the gait pattern of typically developed people when they mimicked pelvic anteversion and posteroversion. Materials and methods: Seventeen healthy volunteers were enrolled in this study (mean age 24.4 ± 5.5). They simulated a pelvic anteversion and posteroversion during walking, exaggerating these postures as much as possible. 3D gait analysis was conducted using an optoelectronic system with eight cameras (Vicon MX, Oxford, United Kingdom) and two force plates (AMTI, Or-6, Watertown, MA, United States). The kinematic, kinetic, and spatio-temporal parameters were compared between the three walking conditions (anteversion, posteroversion, and normal gait). Results: In Pelvic Anteversion gait (PA) we found: increased hip flexion (p < 0.0001), increased knee flexion during stance (p = 0.02), and reduction of ankle flexion-extension Range of Motion (RoM) compared with Pelvic Normal gait (PN). In Pelvic Posteroversion gait (PP) compared with PN, we found: decreased hip flexion-extension RoM (p < 0.01) with a tendency to hip extension, decreased knee maximum extension in stance (p = 0.033), and increased ankle maximum dorsiflexion in stance (p = 0.002). Conclusion: The configuration of PA contains gait similarities and differences when compared with pathologic gait where there is an anteversion as seen in children with Cerebral Palsy (CP) or Duchenne Muscular Dystrophy (DMD). Similarly, attitudes of PP have been described in patients with Charcot-Marie-Tooth Syndrome (CMT) or patients who have undergone Pelvic Osteotomy (PO). Understanding the dynamic biomechanical constraints is essential to the assessment of pathological behavior. The central nervous system adapts motor behavior in interaction with body constraints and available resources.

Comparison of the Gait Biomechanical Constraints in Three Different Type of Neuromotor Damages.

Background and Objective: Absolute angle represents the inclination of a body segment relative to a fixed reference in space. This work compares the absolute and relative angles for exploring biomechanical gait constraints. Methods: Gait patterns of different neuromotor conditions were analyzed using 3D gait analysis: normal gait (healthy, H), Cerebral Palsy (CP), Charcot Marie Tooth (CMT) and Duchenne Muscular Dystrophy (DMD), representing central and peripheral nervous system and muscular disorders, respectively. Forty-two children underwent gait analysis: 10 children affected by CP, 10 children by CMT, 10 children by DMD and 12 healthy children. The kinematic and kinetic parameters were collected to describe the biomechanical pattern of participants' lower limbs. The absolute angles of thigh, leg and foot were calculated using the trigonometric relationship of the tangent. For each absolute series, the mean, range, maximum, minimum and initial contact were calculated. Kinematic and kinetic gait data were studied, and the results were compared with the literature. Results: Statistical analysis of the absolute angles showed how, at the local level, the single segments (thigh, leg and foot) behave differently depending on the pathology. However, if the lower limb is studied globally (sum of the kinematics of the three segments: thigh, leg and foot), a biomechanical constraint emerges. Conclusion: Each segment compensates separately for the disease deficit so as to maintain a global biomechanical invariance. Using a model of inter-joint co-variation could improve the interpretation of the clinical gait pattern.

Compartmental models for diffusion weighted MRI reveal widespread brain changes in HIV-infected patients.

Diffusion tensor imaging (DTI) has been used to explore changes in the brain of subjects with human immunodeficiency virus (HIV) infection. However, DTI notoriously suffers from low specificity. Neurite orientation dispersion and density imaging (NODDI) is a compartmental model able to provide specific microstructural information with additional sensitivity/specificity. In this study we use both the NODDI and the DTI models to evaluate microstructural differences between 35 HIV-positive patients and 20 healthy controls. Diffusion-weighted imaging was acquired using three b-values (0, 1000 and 2500 s/mm2). Both DTI and NODDI models were fitted to the data, obtaining estimates for fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), axial diffusivity (AD), neurite density index (NDI) and orientation dispersion index (ODI), after which we performed group comparisons using Tract-based spatial statistics (TBSS). While significant group effects were found in in FA, MD, RD, AD and NDI, NDI analysis uncovered a much wider involvement of brain tissue in HIV infection as compared to DTI. In region-of interest (ROI)-based analysis, NDI estimates from the right corticospinal tract produced excellent performance in discriminating the two groups (AUC = 0.974, sensitivity = 90%; specificity =97%).

Neuroimaging findings in leukoencephalopathy with calcifications and cysts: case report and review of the literature.

Leukoencephalopathy with cerebral calcifications and cysts (LCC) is a neurological disorder characterized by the radiological triad of white matter abnormalities, intracranial calcifications and cystic lesions variable in size resulting from a diffuse cerebral microangiopathy. Typically, progressive focal neurological deficits and seizures are the first clinical manifestation, but the severity of symptoms can vary according to the size and location of the cystic lesions holding compressive effects on the surrounding brain tissue. The most common histopathological finding is diffuse microangiopathy, which might be associated to pathogenic mutations in SNORD118 gene causing Labrune syndrome. Similar neuroradiological appearances have been found in the Coats plus syndrome, a systemic disorder caused by a genetic diffuse microangiopathy that affects not only the brain but also the retina and multiple organs, with a more complex clinical picture that address the diagnosis; biallelic mutations in CTC1 gene, encoding the conserved telomere maintenance component 1 (CTC1), are responsible of this systemic disorder. The aim of this contribution is to review the existing literature focusing on the neuroimaging characteristics by reporting cases in which radiological findings were highly suggestive for LCC.

Qualitative and quantitative analysis of 3D T1 Silent imaging.

PURPOSE: To compare brain magnetic resonance imaging (MRI) using T1 3D Silent and fast T1 3D Gradient-Echo (GRE) BRAin VOlume (known as BRAVO) sequences. The primary aim is to assess the quantitative and qualitative analysis of Silent and BRAVO images by the measurement of the contrast (C), the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR). The second aim is to estimate the subjective sound levels and the specific absorption rate (SAR). METHODS: Twenty-two subjects had T1 3D Silent and T1 3D BRAVO sequences added to the standard MR examination. The qualitative analysis of the two sequences was performed by two radiologists independently. The quantitative analysis was performed by placing regions of interest on the cerebrospinal fluid, on the white and grey matter. The C, the CNR and the SNR were calculated for each sequence. After each T1-3D sequence, subjects gave a score rating to evaluate the acoustic noise. Finally, the SAR was evaluated by the digital imaging and communications in medicine (DICOM) tags. RESULTS: The image quality scores obtained by the two radiologists were higher for BRAVO compared to the Silent. However, qualitatively, the Silent images were similar to BRAVO for diagnostic use. Quantitatively, CNR for GM-CSF was comparable in the two sequences and SNR in CSF was higher in Silent than BRAVO. The acoustic noise of Silent sequence was statistically lower compared with BRAVO. The maximum SAR measured was 1.4 W/kg. CONCLUSIONS: 3D T1 Silent can be a valid alternative technique to conventional BRAVO to reduce the acoustic noise preserving the diagnostic accuracy. However, radiologists preferred the conventional sequence to Silent.

Global and local brain connectivity changes associated with sudden unilateral sensorineural hearing loss.

Recent studies suggest that even moderate sudden sensorineural hearing loss (SSNHL) causes reduction of gray matter volume in the primary auditory cortex, diminishing its ability to react to sound stimulation, as well as reorganization of functional brain networks. We employed resting-state functional MRI (rs-fMRI), in conjunction with graph-theoretical analysis and a newly developed functional "disruption index," to study whole-brain as well as local functional changes in patients with unilateral SSNHL. We also assessed the potential of graph-theoretical measures as biomarkers of disease, in terms of their relationship to clinically relevant audiological parameters. Eight patients with moderate or severe unilateral SSNHL and 15 healthy controls were included in this prospective pilot study. All patients underwent rs-fMRI to study potential changes in brain connectivity. From rs-fMRI data, global and local graph-theoretical measures, disruption index, and audiological examinations were estimated. Mann-Whitney U tests were used to study the differences between SSNHL patients and healthy controls. Associations between brain metrics and clinical variables were studied using multiple linear regressions, and the presence or absence of brain network hubs was assessed using Fisher's exact test. No statistically significant differences between SSNHL patients and healthy controls were found in global or local network measures. However, when analyzing brain networks through the disruption index, we found a brain-wide functional network reorganization (p < 0.001 as compared with controls), whose extent was associated with clinical impairment (p < 0.05). We also observed several functional hubs in SSNHL patients that were not present in healthy controls and vice versa. Our results demonstrate a brain involvement in SSNHL patients, not detectable using conventional graph-theoretical analysis, which may yield subtle disease clues and possibly aid in monitoring disease progression in clinical trials.

Functional brain network reorganization in HIV infection.

BACKGROUND AND PURPOSE: To investigate the reorganization of the central nervous system provided by resting state-functional MRI (rs-fMRI), graph-theoretical analysis, and a newly developed functional brain network disruption index in patients with human immunodeficiency virus (HIV) infection. METHODS: Forty HIV-positive patients without neurological impairment and 20 age- and sex-matched healthy controls underwent rs-fMRI at 3T; blood sampling was obtained the same day to evaluate biochemical variables (absolute, relative, and nadir CD4 T-lymphocytes value and plasmatic HIV-RNA). From fMRI data, disruption indices, as well as global and local graph theoretical measures, were estimated and examined for group differences (HIV vs. controls) as well as for associations with biochemical variables (HIV only). Finally, all data (global and local graph-theoretical measures, disruption indices, and biochemical variables) were tested for putative differences across three patient groups based on the duration of combined antiretroviral therapy (cART). RESULTS: Brain function of HIV patients appeared to be deeply reorganized as compared to normal controls. The disruption index showed significant negative association with relative CD4 values, and a positive significant association between plasmatic HIV-RNA and local graph-theoretical metrics in the left lingual gyrus and the right lobule IV and V of right cerebellar hemisphere was also observed. Finally, a differential distribution of HIV clinical biomarkers and several brain metrics was observed across cART duration groups. CONCLUSION: Our study demonstrates that rs-fMRI combined with advanced graph theoretical analysis and disruption indices is able to detect early and subtle functional changes of brain networks in HIV patients.

Robotic-assisted locomotor treadmill therapy does not change gait pattern in children with cerebral palsy.

Although robotic-assisted locomotor treadmill therapy is utilized on children with cerebral palsy (CP), its impact on the gait pattern in childhood is not fully described. We investigated the outcome of robotized gait training focusing on the gait pattern modifications and mobility in individuals with CP. An additional intention is to compare our results with the previous literature advancing future solutions. Twenty-four children with diplegic CP (average age 6.4 years old with Gross Motor Functional Classification System range I-IV) received robotized gait training five times per week for 4 weeks. Gait analysis and Gross Motor Function Measurement (GMFM) assessments were performed before and at the end of the treatment. Gait analysis showed inconsistent modifications of the gait pattern. GMFM showed a mild improvement of the dimension D in all subjects, while dimension E changed only in the younger and more severely affected patients. In this study, a detailed investigation comprehensive of electromyography patterns, where previous literature reported only sparse data without giving information on the whole gait pattern, were conducted. We carried on the analysis considering the age of the participants and the severity of the gait function. The findings differentiate the concept of specific pattern recovery (no gait pattern changes) from the concept of physical training (mild GMFM changes).

Reorganization of the structural connectome in primary open angle Glaucoma.

Primary open angle Glaucoma (POAG) is one of the most common causes of permanent blindness in the world. Recent studies have suggested the hypothesis that POAG is also a central nervous system disorder which may result in additional (i.e., extra-ocular) involvement. The aim of this study is to assess possible structural, whole-brain connectivity alterations in POAG patients. We evaluated 23 POAG patients and 15 healthy controls by combining multi-shell diffusion weighted imaging, multi-shell, multi-tissue probabilistic tractography, graph theoretical measures and a recently designed 'disruption index', which evaluates the global reorganization of brain networks. We also studied the associations between the whole-brain structural connectivity measures and indices of visual acuity including the field index (VFI) and two Optical Coherence Tomography (OCT) parameters, namely the Macula Ganglion Cell Layer (MaculaGCL) and Retinal Nerve Fiber Layer (RNFL) thicknesses. We found both global and local structural connectivity differences between POAG patients and controls, which extended well beyond the primary visual pathway and were localized in the left calcarine gyrus (clustering coefficient p = 0.036), left lateral occipital cortex (clustering coefficient p = 0.017, local efficiency p = 0.035), right lingual gyrus (clustering coefficient p = 0.009), and right paracentral lobule (clustering coefficient p = 0.009, local efficiency p = 0.018). Group-wise (clustering coefficient, p = 6.59∙10-7 and local efficiency p = 6.23·10-8) and subject-wise disruption indices (clustering coefficient, p = 0.018 and local efficiency, p = 0.01) also differed between POAG patients and controls. In addition, we found negative associations between RNFL thickness and local measures (clustering coefficient, local efficiency and strength) in the right amygdala (local efficiency p = 0.008, local strength p = 0.016), right inferior temporal gyrus (clustering coefficient p = 0.036, local efficiency p = 0.042), and right temporal pole (local strength p = 0.008). Overall, we show, in patients with POAG, a whole-brain structural reorganization that spans across a variety of brain regions involved in visual processing, motor control, and emotional/cognitive functions. We also identified a pattern of brain structural changes in relation to POAG clinical severity. Taken together, our findings support the hypothesis that the reduction in visual acuity from POAG can be driven by a combination of local (i.e., in the eye) and more extended (i.e., brain) effects.

Disruption of brain network organization in patients with human immunodeficiency virus (HIV) infection.

In 2019, approximately 38 million people were living with human immunodeficiency virus (HIV). Combined antiretroviral therapy (cART) has determined a change in the course of HIV infection, transforming it into a chronic condition which results in cumulative exposure to antiretroviral drugs, inflammatory effects and aging. Relatedly, at least one quarter of HIV-infected patients suffer from cognitive, motor and behavioral disorder, globally known as HIV-associated neurocognitive disorders (HAND). In this context, objective, neuroimaging-based biomarkers are therefore highly desirable in order to detect, quantify and monitor HAND in all disease stages. In this study, we employed functional MRI in conjunction with graph-theoretical analysis as well as a newly developed functional brain network disruption index to assess a putative functional reorganization in HIV positive patients. We found that brain function of HIV patients is deeply reorganized as compared to normal controls. Interestingly, the regions in which we found reorganized hubs are integrated into neuronal networks involved in working memory, motor and executive functions often altered in patients with HAND. Overall, our study demonstrates that rs-fMRI combined with advanced graph theoretical analysis and disruption indices is able to detect early, subtle functional changes of brain networks in HIV patients before structural changes become evident.

Global and local reorganization of brain network connectivity in sudden sensorineural hearing loss.

Recent reports suggested that even moderate sudden sensorineural hearing loss (SSNHL) can be partly responsible for a loss of gray matter volume in the primary auditory cortex, hence reducing the capacity of the auditory cortical areas to react to sound stimulation. There is also evidence for a plastic reorganization of brain functional networks visible as enhanced local functional connectivity. The aim of this study was to use rs-fMRI, in conjunction with graph- theoretical analysis and a newly developed functional "disruption index" to study whole-brain as well as local functional changes in patients with acute and unilateral sensorineural hearing loss. No statistically significant differences in global or local network measures we found between SSNHL patients and healthy controls. However, when analyzing local metrics through the disruption index k, we found negative values for k which were statistically different from zero both in single subject analysis. Additionally, we found several associations between graph-theoretical metrics and clinical parameters.

Diffusional Kurtosis Imaging of White Matter Degeneration in Glaucoma.

Glaucoma is an optic neuropathy characterized by death of retinal ganglion cells and loss of their axons, progressively leading to blindness. Recently, glaucoma has been conceptualized as a more diffuse neurodegenerative disorder involving the optic nerve and also the entire brain. Consistently, previous studies have used a variety of magnetic resonance imaging (MRI) techniques and described widespread changes in the grey and white matter of patients. Diffusion kurtosis imaging (DKI) provides additional information as compared with diffusion tensor imaging (DTI), and consistently provides higher sensitivity to early microstructural white matter modification. In this study, we employ DKI to evaluate differences among healthy controls and a mixed population of primary open angle glaucoma patients ranging from stage I to V according to Hodapp-Parrish-Anderson visual field impairment classification. To this end, a cohort of patients affected by primary open angle glaucoma (n = 23) and a group of healthy volunteers (n = 15) were prospectively enrolled and underwent an ophthalmological evaluation followed by magnetic resonance imaging (MRI) using a 3T MR scanner. After estimating both DTI indices, whole-brain, voxel-wise statistical comparisons were performed in white matter using Tract-Based Spatial Statistics (TBSS). We found widespread differences in several white matter tracts in patients with glaucoma relative to controls in several metrics (mean kurtosis, kurtosis anisotropy, radial kurtosis, and fractional anisotropy) which involved localization well beyond the visual pathways, and involved cognitive, motor, face recognition, and orientation functions amongst others. Our findings lend further support to a causal brain involvement in glaucoma and offer alternative explanations for a number of multidomain impairments often observed in glaucoma patients.

Diffusion kurtosis imaging in head and neck cancer: A correlation study with dynamic contrast enhanced MRI.

PURPOSE: To investigate the biophysical meaning of Diffusion Kurtosis Imaging (DKI) parameters via correlations with the perfusion parameters obtained from a long Dynamic Contrast Enhanced MRI scan, in head and neck (HN) cancer. METHODS: Twenty two patients with newly diagnosed HN tumor were included in the present retrospective study. Some patients had multiple lesions, therefore a total of 26 lesions were analyzed. DKI was acquired using 5b values at 0, 500, 1000,1500 and 2000 s/mm2. DCE-MRI was obtained with 130 dynamic volumes, with a temporal resolution of 5 s, to achieve a long scan time (>10 min). The apparent diffusion coefficient Dapp and apparent diffusional kurtosis Kapp were calculated voxel-by-voxel, removing the point at b value = 0 to eliminate possible perfusion effects on the parameter estimations. The transfer constants Ktrans and Kep, ve, and the histogram-based entropy (En) and interquartile range (IQR) of each DCE-MRI parameter were quantified. Correlations between all variables were investigated by the Spearman's Rho correlation test. RESULTS: Moderate relationships emerged between Dapp and Kep (Rho =  - 0.510, p = 0.009), and between Dapp and ve (Rho = 0.418, p = 0.038). En(Kep) was significantly related to Kapp (Rho = 0.407, p = 0.043), while IQR(Kep) showed an inverse association with Dapp (Rho = -0.422, p = 0.035). CONCLUSIONS: A weak to intermediate correlation was found between DKI parameters and both Kep and ve. The kurtosis was associated to the intratumoral heterogeneity and complexity of the capillary permeability, expressed by En(Kep).

Radiological imaging in multiple myeloma: review of the state-of-the-art.

PURPOSE: Multiple myeloma is a type of blood cancer arising from the uncontrolled clonal proliferation of malignant plasma cells resulting in impaired hematopoiesis, hyper production of monoclonal protein, bone tissue destruction leading and renal system alterations up to kidney failure. The aim is to review the state-of-the-art of radiological imaging in multiple myeloma. METHODS: Radiological techniques as well as the advancements in imaging technology have been reviewed and summarized. The main radiological findings of different imaging techniques in patients suffering from multiple myeloma are also illustrated. RESULTS: Different radiological techniques provide structural and functional data. In the last years, conventional skeletal survey has gradually lost its utility and it has been replaced by whole body low-dose computed tomography which allows to identify also small lytic lesions, the medullary and the extramedullary involvement. Nowadays, magnetic resonance is the most sensitive imaging technique for detecting of skeletal as well as medullary involvement in patients with multiple myeloma. Thanks to the multiparametric evaluation (morphological, diffusion weighted and perfusion imaging sequences) and to the quantitative analysis, magnetic resonance imaging is proved to be useful in the early evaluation of response to therapy. Finally, positron emission tomography has greater sensibility compared to computed tomography as it provides quantitative data; however, the lower expression levels of the specific gene involved in the glycolysis pathway are associated with false-negative results with consequent underestimation of the disease. CONCLUSION: The only use of the advanced combined multimodal imaging allows a better evaluation, staging and early assessment of treatment response in patients with multiple myeloma.