Tesla Magnetic Resonance Imaging Research Articles

Evaluation of High Intracranial Plaque Prevalence in Type 2 Diabetes Using Vessel Wall Imaging on 7 T Magnetic Resonance Imaging

While type 2 diabetes (T2D) is a major risk for ischemic stroke, the associated vessel wall characteristics remain essentially unknown. This study aimed to clarify intracranial vascular changes on three-dimensional vessel wall imaging (3D-VWI) using fast spin echo by employing 7Tesla (7T) magnetic resonance imaging (MRI) in T2D patients without advanced atherosclerosis as compared to healthy controls. In 48 T2D patients and 35 healthy controls, the prevalence of cerebral small vessel diseases and intracranial plaques were evaluated by 3D-VWI with 7T MRI. The prevalence rate of lacunar infarction was significantly higher in T2D than in controls (n = 8 in T2D vs. n = 0 in control, p = 0.011). The mean number of intracranial plaques in both anterior and posterior circulation of each subject was significantly larger in T2D than in controls (2.23 in T2D vs. 0.94 in control, p < 0.01). In T2D patients, gender was associated with the presence of intracranial plaques. This is the first study to demonstrate the high prevalence of intracranial plaque in T2D patients with neither confirmed atherosclerotic disease nor symptoms by performing intracranial 3D-VWI employing 7TMRI. Investigation of intracranial VWI with 7T MRI is expected to provide novel insights allowing early intensive risk management for prevention of ischemic stroke in T2D patients.

Elevated Plasma Oligomeric Amyloid β-42 Is Associated with Cognitive Impairments in Cerebral Small Vessel Disease

Due to the heterogeneity of amyloid β-42 (Aβ42) species, the potential correlation between plasma oligomeric Aβ42 (oAβ42) and cognitive impairments in cerebral small vessel disease (CSVD) remains unclear. Herein, a sandwich ELISA for the specific detection of Aβ42 oligomers (oAβ42) and total Aβ42 (tAβ42) was developed based on sequence- and conformation-specific antibody pairs for the evaluation of plasma samples from a Chinese CSVD community cohort. After age and gender matching, 3-Tesla magnetic resonance imaging and multidimensional cognitive assessment were conducted in 134 CSVD patients and equal controls. The results showed that plasma tAβ42 and oAβ42 levels were significantly elevated in CSVD patients. By regression analysis, these elevations were correlated with the presence of CSVD and its imaging markers (i.e., white matter hyperintensities). Plasma Aβ42 tests further strengthened the predictive power of vascular risk factors for the presence of CSVD. Relative to tAβ42, oAβ42 showed a closer correlation with memory domains evaluated by neuropsychological tests. In conclusion, this sensitive ELISA protocol facilitated the detection of plasma Aβ42; Aβ42, especially its oligomeric form, can serve as a biosensor for the presence of CSVD and associated cognitive impairments represented by memory domains.

A radiomic signature based on magnetic resonance imaging to determine adrenal Cushing's syndrome.

The aim of this study was to develop radiomics signature-based magnetic resonance imaging (MRI) to determine adrenal Cushing's syndrome (ACS) in adrenal incidentalomas (AI). A total of 50 patients with AI were included in this study. The patients were grouped as nonfunctional adrenal incidentaloma (NFAI) and ACS. The lesions were segmented on unenhanced T1-weighted (T1W) in-phase (IP) and opposed-phase (OP) as well as on T2-weighted (T2-W) 3-Tesla MRIs. The LASSO regression model was used for the selection of potential predictors from 111 texture features for each sequence. The radiomics scores were compared between the groups. The median radiomics score in T1W-Op for the NFAI and ACS were -1.17 and -0.17, respectively (p < 0.001). Patients with ACS had significantly higher radiomics scores than NFAI patients in all phases (p < 0.001 for all). The AUCs for radiomics scores in T1W-Op, T1W-Ip, and T2W were 0.862 (95% CI: 0.742-0.983), 0.892 (95% CI: 0.774-0.999), and 0.994 (95% CI: 0.982-0.999), respectively. The developed MRI-based radiomic scores can yield high AUCs for prediction of ACS.

Comparative study between dynamic susceptibility contrast magnetic resonance imaging and arterial spin labelling perfusion in differentiating low-grade from high-grade brain tumours.

Our aim was to distinguish between low-grade and high-grade brain tumours on the basis of dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) perfusion and arterial spin labelling (ASL) perfusion and to compare DSC and ASL techniques. Forty-one patients with brain tumours were evaluated by 3-Tesla MRI. Conventional and perfusion MRI imaging with a 3D pseudo-continuous ASL (PCASL) and DSC perfusion maps were evaluated. Three ROIs were placed to obtain cerebral blood value (CBV) and cerebral blood flow (CBF) in areas of maximum perfusion in brain tumour and normal grey matter. Histopathological diagnosis was considered as the reference. ROC analysis was performed to compare the diagnostic performance and to obtain a feasible cut-off value of perfusion parameters to differentiate low-grade and high-grade brain tumours. Normalised perfusion parameters with grey matter (rCBF or rCBV lesion/NGM) of malignant lesions were significantly higher than those of benign lesions in both DSC (normalised rCBF of 2.16 and normalised rCBV of 2.63) and ASL (normalised rCBF of 2.22) perfusion imaging. The normalised cut-off values of DSC (rCBF of 1.1 and rCBV of 1.4) and ASL (rCBF of 1.3) showed similar specificity and near similar sensitivity in distinguishing low-grade and high-grade brain tumours. Quantitative analysis of perfusion parameters obtained by both DSC and ASL perfusion techniques can be reliably used to distinguish low-grade and high-grade brain tumours. Normalisation of these values by grey matter gives us more reliable parameters, eliminating the different technical parameters involved in both the techniques.

Arterial stiffness and its influence on cerebral morphology and cognitive function.

Recently, arterial stiffness has been associated with cerebral small vessel disease (SVD), brain atrophy and vascular dementia. Arterial stiffness is assessed via pulse wave velocity (PWV) measurement and is strongly dependent on arterial blood pressure. While circadian blood pressure fluctuations are important determinants of end-organ damage, the role of 24-h PWV variability is yet unclear. We here investigated the association between PWV and its circadian changes on brain morphology and cognitive function in community-dwelling individuals. Single-centre, prospective, community-based follow-up study. The study cohort comprised elderly community-based participants of the Austrian Stroke Prevention Family Study which was started in 2006. Patients with any history of cerebrovascular disease or dementia were excluded. The study consists of 84 participants who underwent ambulatory 24-h PWV measurement. White matter hyperintensity volume and brain volume were evaluated by 3-Tesla magnetic resonance imaging (MRI). A subgroup of patients was evaluated for cognitive function using an extensive neuropsychological test battery. PWV was significantly related to reduced total brain volume (p = 0.013), which was independent of blood pressure and blood pressure variability. We found no association between PWV with markers of cerebral SVD or impaired cognitive functioning. Only night-time PWV values were associated with global brain atrophy (p = 0.005). This study shows a relationship of arterial stiffness and reduced total brain volume. Elevations in PWV during night-time are of greater importance than day-time measures.

Cortical Thickness and Brain Glucose Metabolism in Healthy Aging.

We aimed to determine the effect of demographic factors on cortical thickness and brain glucose metabolism in healthy aging subjects. The following tests were performed on 71 subjects with normal cognition: neurological examination, 3-tesla magnetic resonance imaging, 18F-fluorodeoxyglucose positron-emission tomography, and neuropsychological tests. Cortical thickness and brain metabolism were measured using vertex- and voxelwise analyses, respectively. General linear models (GLMs) were used to determine the effects of age, sex, and education on cortical thickness and brain glucose metabolism. The effects of mean lobar cortical thickness and mean lobar metabolism on neuropsychological test scores were evaluated using GLMs after controlling for age, sex, and education. The intracranial volume (ICV) was further included as a predictor or covariate for the cortical thickness analyses. Age was negatively correlated with the mean cortical thickness in all lobes (frontal and parietal lobes, p=0.001; temporal and occipital lobes, p<0.001) and with the mean temporal metabolism (p=0.005). Education was not associated with cortical thickness or brain metabolism in any lobe. Male subjects had a lower mean parietal metabolism than did female subjects (p<0.001), while their mean cortical thicknesses were comparable. ICV was positively correlated with mean cortical thickness in the frontal (p=0.016), temporal (p=0.009), and occipital (p=0.007) lobes. The mean lobar cortical thickness was not associated with cognition scores, while the mean temporal metabolism was positively correlated with verbal memory test scores. Age and sex affect cortical thickness and brain glucose metabolism in different ways. Demographic factors must therefore be considered in analyses of cortical thickness and brain metabolism.

PS-B10-10: MRI CEREBROVASCULAR CHARACTERIZATION IN A MOUSE MODEL OF HYPERTENSION-INDUCED BRAIN INJURY

Hypertension has been recognized as the main modifiable risk factor for vascular cognitive impairment (VCI), dementias and neurodegenerative pathologies as Alzheimer Disease (AD). As we previously demonstrated, Transverse aortic constriction (TAC) is a relevant mouse model of cerebral injury and cognitive impairment induced by vascular factors. In this work we characterize the effect of TAC procedure on cerebral injury leveraging Magnetic Resonance Imaging (MRI), and investigate the relationship between the alterations found by MRI and histological, cognitive and cardiac parameters of injury, to establish a framework of translational imaging biomarkers to be applied in human. We subjected C57Bl/6J to TAC procedure, inducing severe cerebral hypertension. Thereafter, the brain injury was characterized by macro and microstructural MRI; cerebral blood flow (CBF) was analyzed by perfusion MRI. All neuroimaging scans were performed on a small-animal dedicated 7 Tesla MRI. The cognitive phenotype was characterized by Morris Water Maze (MWM) and Novel Object Recognition (NOR), while cardiac and carotid remodeling was assessed by ultrasound imaging. Finally, brains were analyzed for histological alterations in terms of microvascular density and integrity. Structural MRI showed white matter microstructural degradation in the left Fimbria of TAC mice, evidenced by a reduction of Fractional Anisotropy, Mean Diffusivity and Radial Diffusiity, coupled with bilateral hypothalamic enlargement (Figure A). Hemodynamic alterations resulted in reduced global, cortical and hypothalamic CBF (Figure B). The histological microvascular analysis evidenced capillary rarefaction, reduced capillary-pericyte coverage and Blood-Brain Barrier leakiness in the neocortex (Figure C). Finally, we evaluated whether cerebral MRI parameters of injury were correlated with cardiac, carotid and cognitive alterations: CBF was significantly correlated with mouse performance at Probe trial of MWM test and correlated to cardiac remodeling and diastolic dysfunction. Diastolic disfunction was correlated also to hypothalamic swelling, and cardiac remodeling was significantly correlated to microstructural alterations in the fimbria. Finally, CBF was correlated to bilateral carotid remodeling. In conclusion we have developed a mouse model of hypertension-induced brain damage that recapitulates typical traits of the human pathology and a pipeline of analysis that will ease allow to appreciate findings resulting from novel molecular targeting of the brain and translate them from bench to bedside. JOURNAL/jhype/04.03/00004872-202301001-01152/figure1/v/2023-10-24T163949Z/r/image-jpeg

Utility of Contrast-enhanced 3D T1-weighted CUBE Fat Sat Sequence MRI to Evaluate Pathological Cranial Nerve EnhancementA Prospective Longitudinal Study

Introduction: Abnormal Cranial Nerve (CN) enhancement can point towards an underlying disorder or disease severity. Therefore, the depiction of this feature is of utmost importance in the evaluation of various pathologies. Various Magnetic Resonance Imaging (MRI) sequences have a role in the early identification of such findings. Aim: To study the spectrum of cases of abnormal CN enhancement on MRI and the role of contrast-enhanced 3 Dimensional (3D) T1-weighted CUBE Fat saturated sequence in evaluating pathological CN enhancement. Materials and Methods: This prospective longitudinal study was conducted in the Department of Radiodiagnosis at Indira Gandhi Institute of Medical Sciences, Patna, Bihar, India. The duration of the study was 2 years, from June 2020 to June 2022. Study included 50 patients who presented with signs and symptoms of CN involvement or were referred for other pathologies with incidental detection of pathological nerve enhancement on 1.5 Tesla (T) MRI Scanner. The data was transferred to a Microsoft Excel 2010 sheet and results were expressed in terms of frequency and percentages. Results: The mean age of the study participants was 33.3±20.9 years. Male to female ratio was 28:22=1.27:1. Infections were the most common cause of abnormal CN enhancement 26 (52%) cases followed by demyelination 3 (6%) cases, haematological malignancy 4 (8%) cases, metastatic neural infiltration 5 (20%), primary neural tumours 4 (18%), Bell’s palsy 1 (2%) case, Tolosa Hunt Syndrome (THS) 1 (2%) case and idiopathic polyneuritis cranialis 1 (2%) case. Conclusion: Contrast-enhanced 3D T1 CUBE Fat-saturation (FS) sequence is excellent in depicting abnormal CN enhancement, especially the cisternal segments.

Diffusion Tensor MRI of Brain in Healthy Adult Population: Normative Fractional Anisotropy Values at 3 Tesla MRI

Introduction: Diffusion Tensor Imaging (DTI) technique and its clinical application are increasing in clinical routine practice, still very less normative data is available. Awareness regarding regional differences in Fractional Anisotropy (FA) measurements is very important when routinely DTI is used in clinical Magnetic Resonance Imaging (MRI). Aim: To determine the normative FA values data at 3 Tesla (3T) MRI and to determine the degradation of FA values in various regions of brain values with age. Materials and Methods: This cross-sectional study involved a total of 52 participants without any abnormal findings ( presence of tumour, stroke, infarct, degeneration, etc) and whose brain scanning was performed at 3T MRI, in the Department of Radiodiagnosis, Shree Krishna Hospital, and Pramukhswami Medical College, Karamsad, Anand, Gujarat, India. A DTI protocol was set for the healthy patient’s brain scanning. The colour-coded DTI brain images were postprocessed carefully to draw a circular Region of Interest (ROI) in the required areas of white matter and FA values were noted. Descriptive statistics were used to find out the normative data in 11 regions of the brain on right and left side. Pearson correlation was used to check the correlation of FA values with age. Results: There were 52 patients in the present study, with a male to female ratio of 1.7:1 and a mean age of 52 years. The highest FA values were observed in the splenium (0.809), genu (0.767), the body of the corpus callosum (0.627), and the posterior limb of the internal capsule (0.721), rest areas showed moderate to low FA values. Pearson correlation was used to find the variation in the FA values with age in three age groups 18-40, 41-60 and &gt;60 years, where moderate changes in FA values with age were seen in a few regions of the brain such as genu (right side) with p-value=0.003 and foramen magnum at CVJ level (right side) with a p-value of 0.001. Conclusion: Generally, FA values intend to change with the presence of multiple tract areas, field strength, coil sensitivity, and partial volume averaging. FA values were also found to be affected with respect to increasing age.

Risk of magnetic resonance imaging-induced magnet dislocation for different types of cochlear implants: a single-center retrospective study

BackgroundWhen performing magnetic resonance imaging (MRI) in patients with a cochlear implant (CI), complication rates vary widely in the literature. The primary objective of this retrospective study was to determine the prevalence of complications, in particular magnet dislocation, in patients with CI undergoing 1.5 Tesla (T) MRI. As a secondary objective, the prevalence of magnet dislocation for specific cochlear implant device types was elaborated.MethodsIn a single-center retrospective study, all patients with a cochlear implant presenting for an MRI examination at 1.5 T at our institution between January 1st, 2010 and December 31st, 2020 were included. Implants with axial and diametrical magnets were included in the study. MRI safety measures were applied before imaging. The prevalence of complications was evaluated. Magnet dislocation rates were calculated for device types with at least 20 MRI exposures.ResultsDuring the study period, 196 MRI examinations were performed in a total of 128 patients, accounting for 149 different implants (21 implanted bilaterally) with a total of 231 implant exposures to MRI (average 1.69 ± 1.57; min. 1, max. 12). Complications were reported in 50 out of 231 cochlear implant exposures (21.6%). Magnet dislocation occurred in a total of 27 cases (11.7%). Dislocation rates were 29.6% for the Cochlear® CI500 series (24 dislocations from 81 exposures), 1.1% for the Cochlear® CI24RE series (1 from 87) and 0% for the MED-EL® Synchrony (0 from 36). The dislocation rate for the CI500 was significantly higher than for the CI24RE (χ2(1) = 26.86; p < 0.001; ϕ = 0.40) or the Synchrony (χ2(1) = 13.42; p < 0.001; ϕ = 0.34).ConclusionsFor 1.5 T MRI, the risk of magnet dislocation ranges from 0 to 29.6% and depends on the CI device type. Implants with a diametrical magnet can be considered potentially MRI-safe, whereas in CIs with axial magnets, the CI500 is at high risk of magnet dislocation. Therefore, apart from a strict indication for an MRI and adherence to safety protocols, post-MRI follow-up examination to rule out magnet dislocation is recommended.Graphical

7T amygdala and hippocampus subfields in volumetry-based associations with memory: A 3-year follow-up study of early Alzheimer’s disease

IntroductionThe hippocampus is the most prominent single region of interest (ROI) for the diagnosis and prediction of Alzheimer’s disease (AD). However, its suitability in the earliest stages of cognitive decline, i.e., subjective cognitive decline (SCD), remains uncertain which warrants the pursuit of alternative or complementary regions. The amygdala might be a promising candidate, given its implication in memory as well as other psychiatric disorders, e.g. depression and anxiety, which are prevalent in SCD. In this 7 tesla (T) magnetic resonance imaging (MRI) study, we aimed to compare the contribution of volumetric measurements of the hippocampus, the amygdala, and their respective subfields, for early diagnosis and prediction in an AD-related study population. MethodsParticipants from a longitudinal study were grouped into SCD (n = 29), mild cognitive impairment (MCI, n = 23), AD (n = 22) and healthy control (HC, n = 31). All participants underwent 7T MRI at baseline and extensive neuropsychological testing at up to three visits (baseline n = 105, 1-year n = 78, 3-year n = 39). Analysis of covariance (ANCOVA) was used to assess group differences of baseline volumes of the amygdala and the hippocampus and their subfields. Linear mixed models were used to estimate the effects of baseline volumes on yearly changes of a z-scaled memory score. All models were adjusted to age, sex and education. ResultsCompared to the HC group, individuals with SCD showed smaller amygdala ROI volumes (range across subfields −11% to −1%), but not hippocampus ROI volumes (-2% to 1%) except for the hippocampus-amygdala-transition-area (-7%). However, cross-sectional associations between baseline memory and volumes were smaller for amygdala ROIs (std. ß [95% CI] ranging between 0.16 [0.08; 0.25] and 0.46 [0.31; 0.60]) than hippocampus ROIs (between 0.32 [0.19; 0.44] and 0.53 [0.40; 0.67]). Further, the association of baseline volumes with yearly memory change in the HC and SCD groups was similarly weak for amygdala ROIs and hippocampus ROIs. In the MCI group, volumes of amygdala ROIs were associated with a relevant yearly memory decline [95% CI] ranging between −0.12 [−0.24; 0.00] and −0.26 [−0.42; −0.09] for individuals with 20% smaller volumes than the HC group. However, effects were stronger for hippocampus ROIs with a corresponding yearly memory decline ranging between −0.21 [−0.35; −0.07] and −0.31 [−0.50; −0.13]. ConclusionVolumes of amygdala ROIs, as determined by 7T MRI, might contribute to objectively and non-invasively identify patients with SCD, and thus aid early diagnosis and treatment of individuals at risk to develop dementia due to AD, however associations with other psychiatric disorders should be evaluated in further studies. The amygdala’s value in the prediction of longitudinal memory changes in the SCD group remains questionable. Primarily in patients with MCI, memory decline over 3 years appears to be more strongly associated with volumes of hippocampus ROIs than amygdala ROIs.

Optimisation of path planning for minimally invasive interventions on prostate using MR-robot: Application to on-live pets

The robot-assisted biopsy system under Magnetic Resonance Imaging (MRI) guidance is a promising candidate for prostate cancer diagnosis in terms of improving the reliability and accuracy of reaching micro-lesions of perineum organ tissues. This has been explored for the last decade. A pre-requisite for effective interventional diagnosis is an accurate intervention planning that is difficult to achieve manually. This is due to multiple factors mainly, the fact that the insertion needles trajectories should avoid organs at risk and limited manoeuvrability, under clinician control. Thus, Biopsy-robot is a feasible solution to improve targeting accuracy. However, the planned trajectories should be consistent with the needle-driven robot's kinematics capabilities. To eliminate these problems, we present an integrated concept composed of MRI-robot and Brachytherapy (BT) path planning algorithm, allowing to minimise the number of entry points of BT needles, from a physical grid to reach all the treatable volume of the prostate gland. This means minimising the number of inserted needles from the perineum, compared to a conventional straight insertion of multiple needles. Indeed, the proposed method is able to set-up safe percutaneous routes defined by a set of oblique straight-line paths linking a minimum number of feasible entry points and desired finite target points, defined within the prostate volume. By adopting such a procedure, the aim is to contribute in minimising tissue damage and patient trauma, and risk of infection, and shortening recovery time. A combinatorial approach is proposed for the minimisation of the insertion point. The development, implementation, and experimental evaluation of the needle path planning method for the 5 Degree of Freedom (DoF) robot guide is presented and performed within a 1.5 Tesla MRI to evaluate how the proposed approach is efficient and reliable on-live pets.

An unsupervised deep learning-based image translation method for retrospective motion correction of high resolution kidney MRI

A primary challenge for in vivo kidney magnetic resonance imaging (MRI) is the presence of different types of involuntary physiological motion, affecting the diagnostic utility of acquired images due to severe motion artifacts. Existing prospective and retrospective motion correction methods remain ineffective when dealing with complex large amplitude nonrigid motion artifacts. Here, we introduce an unsupervised deep learning-based image to image translation method between motion-affected and motion-free image domains, for correction of rigid-body, respiratory and nonrigid motion artifacts in vivo kidney MRI.High resolution (i.e., 156 × 156 × 370 μm) ex vivo 3 Tesla MRI scans of 13 porcine kidneys (because of their anatomical homology to human kidney) were conducted using a 3D T2-weighted turbo spin echo sequence. Rigid-body, respiratory and nonrigid motion-affected images were then simulated using the magnitude-only ex vivo motion-free image set. Each 2D coronal slice of motion-affected and motion-free image volume was then divided into patches of 128 × 128 for training the model. We proposed to add normalised cross-correlation loss to cycle consistency generative adversarial network structure (NCC-CycleGAN), to enforce edge alignment between motion-corrected and motion-free image domains.Our NCC-CycleGAN motion correction model demonstrated high performance with an in-tissue structural similarity index measure of 0.77 ± 0.08, peak signal-to-noise ratio of 26.67 ± 3.44 and learned perceptual image patch similarity of 0.173 ± 0.05 between the reconstructed motion-corrected and ground truth motion-free images. This corresponds to a significant respective average improvement of 34%, 23% and 39% (p < 0.05; paired t-test) for the three metrics to correct the three different types of simulated motion artifacts.We demonstrated the feasibility of developing an unsupervised deep learning-based method for efficient automated retrospective kidney MRI motion correction, while preserving microscopic tissue structures in high resolution imaging.

Quantification of Artifacts and Image Distortions in 1.5 Tesla Magnetic Resonance Images of a Commercial Multi-Channel Vaginal Cylinder Brachytherapy Applicator Set.

The BEBIG Portio multi-channel applicator provides better target dose coverage and sparing organs-at-risk compared to a single-channel cylinder. However, artifacts and distortions of Portio in magnetic resonance images (MRI) have not yet been reported. We aimed to quantify the artifacts and distortions in its 1.5-Tesla MR images before clinical use. In this experimental study, we employed a gelatin-filled phantom to conduct our measurements. T2-weighted (T2W) images were examined for artifacts and distortions. Computed tomography (CT) images were used as a reference to assess image distortions. Artifact severity was measured by recording the full-width-at-half-maximum (FWHM) image pixel values at various positions along the length of the applicator/channels. CT and MRI-based applicator reconstruction accuracy were then compared, and signal-to-noise ratio (SNR) and contrast were also determined for the applicator images. The applicator distortion level for the Portio applicator was less than the image spatial resolution (0.5±0.5 pixels). The average FWHM for the tandem applicator images was 5.23±0.39 mm, while it was 3.21±0.37 mm for all channels (compared to their actual diameters of 5.0 mm and 3.0 mm, respectively). The average applicator reconstruction difference between CT and MR images was 0.75±0.30 mm overall source dwell positions. The image SNR and contrast were both acceptable. These findings indicate that the Portio applicator has a satisfactory low level of artifacts and image distortions in 1.5-Tesla, T2W images. It may, therefore, be a promising option for MRI-guided multi-channel vaginal brachytherapy.

Application of 5-ALA Fluorescence-guided Resection in Patients Suffering From High-grade Gliomas: A Report of 30 Consecutive Cases and a Literature Review

Background and Aim: The extent of resection seems a solid prognostic factor in patients with high-grade gliomas (HGGs). When administered orally, 5-aminolevulinic acid (5-ALA) is exclusively converted into protoporphyrin IX (PPIX) by malignant cells and detects, identifying contrast-enhancing glial lesions under 400 nm blue light. The authors thoroughly assess the efficacy, accuracy, and safety profile of 5-ALA-guided surgery toward the maximal resection of cranial HGGs. Case Presentation: Thirty consecutive patients with HGG adjacent to the corticospinal tract (CST) met our inclusion criteria in a single-arm retrospective study. Bilateral diffusion tensor imaging (DTI)-derived corticospinal tract (CST) tractography was employed using a 1.5 Tesla magnetic resonance imaging (MRI). Oral 5-ALA was ingested with a dose of 20 mg/kg 4 hours prior to operation and was applied to qualify the margins of the local resection cavity. The clinical and volumetric assessments were postoperatively conducted. The mean preoperative tumor volume on T1 contrast-enhanced MRI and fluid-attenuated inversion recovery (FLAIR) images was 16.8 cm3 and 47.6 cm3, respectively. Complete resection of contrast-enhanced lesions was yielded in 27 of 30 patients (90%). All patients improved postoperatively regarding motor deficits and or seizures. No new permanent neurological deficits were detected in the 3-month follow-up. Conclusion: Fluorescence image-guided surgery (FIGS) using 5-ALA increases the extent of resection (EOR) with further surgical risks in eloquent regions when combined with multimodality visualization- functional mapping. It also provides pathological insights to visualize cranial HGGs and identify infiltration of functional fiber tracts.

Classification of low- and high-grade gliomas using radiomic analysis of multiple sequences of MRI brain.

Gliomas are frequent tumors of brain parenchyma, which have histology similar to that of glial cells. Accurate glioma grading is required for determining clinical management. The background of this study is to investigate the accuracy of magnetic resonance imaging (MRI)-based radiomic features extracted from multiple MRI sequences in differentiating low and high-grade gliomas. This is a retrospective study. It includes two groups. Group A includes patients with confirmed histopathological diagnosis of low (23) and high-grade (58) gliomas from 2012 to 2020 were included. The MRI images were acquired using a Signa HDxt 1.5 Tesla MRI (GE Healthcare, Milwaukee, USA). Group B includes an external test set consisting of low- (20) and high-grade gliomas (20) obtained from The Cancer Genome Atlas (TCGA). The radiomic features were extracted from axial T2, apparent diffusion coefficient map, axial T2 fluid-attenuated inversion recovery, and axial T1 post-contrast sequences for both the groups. The Mann - Whitney U test was performed to assess the significant radiomic features useful for distinguishing the glioma grades for Group A. To determine the accuracy of radiomic features for differentiating gliomas, AUC was calculated from receiver operating characteristic curve analysis for both groups. Our study noticed in Group A, fourteen MRI-based radiomic features from four MRI sequences showed a significant difference (p < 0.001) in differentiating gliomas. In Group A, we noticed T1 post-contrast radiomic features such as first-order variance (FOV) (sensitivity - 94.56%, specificity - 97.51%, AUC - 0.969) and GLRLM long-run gray-level emphasis (sensitivity - 97.54%), specificity - 96.53%, AUC - 0.972) had the highest discriminative power for distinguishing the histological subtypes of gliomas. Our study noticed no statistical significant difference between ROC curves of significant radiomic features for both groups. In Group B, the T1 post-contrast radiomic features such as FOV (AUC-0.933) and GLRLM long-run gray-level emphasis (AUC-0.981) had also shown high discriminative power for distinguishing the gliomas. Our study concludes that MRI-based radiomic features extracted from multiple MRI sequences provide a non-invasive diagnosis of low- and high-grade gliomas and can be implemented in clinical settings for diagnosing the glioma grades.

Sensitivity and specificity of 3 Tesla magnetic resonance imaging and multidetector computed tomographic tenography to identify artificially induced soft tissue lesions in the equine cadaveric digital flexor tendon sheath

SummaryBackgroundA common cause of lameness in horses is tenovaginitis of the digital flexor tendon sheath (DFTS). Ultrasound and contrast tenography have become frequently used diagnostic tools for abnormalities in the DFTS, but are considered insufficiently accurate in describing specific lesions.ObjectivesTo determine the sensitivity and specificity of computed tomographic tenography (CTT) and 3 Tesla magnetic resonance imaging (MRI) to detect artificial lesions within the DFTS.Study designBlinded laboratory study.MethodsUsing an arthroscopic hook knife, lesions (10–20 mm long and 3–5 mm deep; n = 52) were created tenoscopically in the superficial digital flexor tendon (SDFT), deep digital flexor tendon (DDFT), manica flexoria (MF) and proximal scutum in 19 distal limb specimens. MRI and CTT were performed and images were reviewed. Sensitivity and specificity were calculated for each modality and compared.ResultsComputed tomographic tenography and MRI identification of SDFT and MF lesions showed similar sensitivity (75% vs. 85%, respectively; p = 1) and specificity for MF lesions (96% for both). SDFT lesions specificity was similar for CTT versus MRI (85% vs. 77%, respectively; p = 0.88). For DDFT lesions, MRI sensitivity (62%) was higher compared to CTT (38%), although not statistically significant (p = 0.58). MRI specificity (92%) was lower than CTT (96%, p = 1). Lesions in the proximal scutum were more frequently identified by MRI compared to CTT (sensitivity: 93% vs. 57%, p = 0.17; specificity: 96% vs. 100%, p = 1).Main limitationsArtificial, small lesions were assessed. An incomplete arthroscopic portal seal resulted in pressure loss and contrast leakage.ConclusionsThe sensitivity and specificity of both modalities are good to excellent for the diagnosis of most artificially created lesions. CTT performed similarly to MRI in detecting SDFT and MF lesions. MRI showed a higher sensitivity for the diagnosis of DDFT and proximal scutum lesions. The results indicate a future application of CTT for the diagnosis of DFTS pathologies, whenever suspecting MF tears.

MyD88-TLR4-dependent choroid plexus activation precedes perilesional inflammation and secondary brain edema in a mouse model of intracerebral hemorrhage.

The functional neurological outcome of patients with intracerebral hemorrhage (ICH) strongly relates to the degree of secondary brain injury (ICH-SBI) evolving within days after the initial bleeding. Different mechanisms including the incitement of inflammatory pathways, dysfunction of the blood-brain barrier (BBB), activation of resident microglia, and an influx of blood-borne immune cells, have been hypothesized to contribute to ICH-SBI. Yet, the spatiotemporal interplay of specific inflammatory processes within different brain compartments has not been sufficiently characterized, limiting potential therapeutic interventions to prevent and treat ICH-SBI. We used a whole-blood injection model in mice, to systematically characterized the spatial and temporal dynamics of inflammatory processes after ICH using 7-Tesla magnetic resonance imaging (MRI), spatial RNA sequencing (spRNAseq), functional BBB assessment, and immunofluorescence average-intensity-mapping. We identified a pronounced early response of the choroid plexus (CP) peaking at 12-24h that was characterized by inflammatory cytokine expression, epithelial and endothelial expression of leukocyte adhesion molecules, and the accumulation of leukocytes. In contrast, we observed a delayed secondary reaction pattern at the injection site (striatum) peaking at 96h, defined by gene expression corresponding to perilesional leukocyte infiltration and correlating to the delayed signal alteration seen on MRI. Pathway analysis revealed a dependence of the early inflammatory reaction in the CP on toll-like receptor 4 (TLR4) signaling via myeloid differentiation factor 88 (MyD88). TLR4 and MyD88 knockout mice corroborated this observation, lacking the early upregulation of adhesion molecules and leukocyte infiltration within the CP 24h after whole-blood injection. We report a biphasic brain reaction pattern after ICH with a MyD88-TLR4-dependent early inflammatory response of the CP, preceding inflammation, edema and leukocyte infiltration at the lesion site. Pharmacological targeting of the early CP activation might harbor the potential to modulate the development of ICH-SBI.

Three Tesla magnetic resonance imaging detects oxalate osteopathy in patients with primary hyperoxaluria type I.

With declining kidney function and therefore increasing plasma oxalate, patients with primary hyperoxaluria type I (PHI) are at risk to systemically deposit calcium-oxalate crystals. This systemic oxalosis may occur even at early stages of chronic kidney failure (CKD) but is difficult to detect with non-invasive imaging procedures. We tested if magnetic resonance imaging (MRI) is sensitive to detect oxalate deposition in bone. A 3 Tesla MRI of the left knee/tibial metaphysis was performed in 46 patients with PHI and in 12 healthy controls. In addition to the investigator's interpretation, signal intensities (SI) within a region of interest (ROI, transverse images below the level of the physis in the proximal tibial metaphysis) were measured pixelwise, and statistical parameters of their distribution were calculated. In addition, 52 parameters of texture analysis were evaluated. Plasma oxalate and CKD status were correlated to MRI findings. MRI was then implemented in routine practice. Independent interpretation by investigators was consistent in most cases and clearly differentiated patients from controls. Statistically significant differences were seen between patients and controls (p < 0.05). No correlation/relation between the MRI parameters and CKD stages or Pox levels was found. However, MR imaging of oxalate osteopathy revealed changes attributed to clinical status which differed clearly to that in secondary hyperparathyroidism. MRI is able to visually detect (early) oxalate osteopathy in PHI. It can be used for its monitoring and is distinguished from renal osteodystrophy. In the future, machine learning algorithms may aid in the objective assessment of oxalate deposition in bone. Graphical Abstract A higher resolution version of the Graphical abstract is available as Supplementary information.

Clinical outcome and healing rate after meniscal bucket handle tear repair

BackgroundReports combining patient-reported outcome measures, clinical evaluation, and radiographic assessment of postoperative healing after arthroscopic repair of bucket-handle meniscal tears (BHMT) are scarce.MethodsPatients who underwent arthroscopic repair for acute traumatic BHMTs between October 2011 and March 2016 with a minimum follow-up of two years were included. Postoperative outcome scores comprised the International Knee Documentation Society Score (IKDC), Lysholm score, Tegner activity score (TAS), and visual analog scale (VAS) for pain. Clinical meniscal healing failure was assessed according to Barrett’s criteria. Side-to-side difference in knee laxity was measured using KT-2000. Radiographic healing was assessed by 3-Tesla magnetic resonance imaging (MRI) and classified according to Henning’s criteria at final follow-up.ResultsForty patients with a mean age of 32.0 ± 11.5 years were available for follow-up after 51.8 ± 14.3 months. Revision surgery by means of arthroscopic partial meniscectomy was performed in four patients (10%) prior to the follow-up visit. The clinical healing rate was 83.3% at final follow-up. Mean IKDC score was 82.8 ± 13.8 and Lysholm score was 77.4 ± 24.8. Of all patients, 87.5% reached or exceeded the patient-acceptable symptomatic state (PASS) criteria for the IKDC score at final follow-up. The median TAS was 6 and VAS for pain was 0.46 ± 0.9. Side-to-side difference in knee laxity was higher in patients with concomitant ACL reconstruction (2.1 ± 2.7 mm) compared to isolated BHMTs (1.0 ± 2.0 mm). MR examination showed 69.4% healed, 25.0% partially healed, and 5.6% unhealed menisci.ConclusionPatients who underwent repair for acute traumatic BHMTs achieved good to excellent clinical outcome along with a high rate of meniscal healing at a minimum follow-up of two years. Clinical and radiological healing rates were similarly satisfactory and most patients exceeded the PASS criteria for the IKDC score. Patients were able to reach a high postoperative activity level.Level of evidenceCase Series; IV.