A critical review of radiotracers in the positron emission tomography imaging of traumatic brain injury: FDG, tau, and amyloid imaging in mild traumatic brain injury and chronic traumatic encephalopathy

Accelerated Aging after Traumatic Brain Injury: An ENIGMA Multi-Cohort Mega-Analysis

OBJECTIVE

The long-term consequences of traumatic brain injury (TBI) on brain structure remain uncertain. Given evidence that a single significant brain injury event increases the risk of dementia, brain-age estimation could provide a novel and efficient indexing of the long-term consequences of TBI. Brain-age procedures use predictive modeling to calculate brain-age scores for an individual using structural magnetic resonance imaging (MRI) data. Complicated mild, moderate, and severe TBI (cmsTBI) is associated with a higher predicted age difference (PAD), but the progression of PAD over time remains unclear. We sought to examine whether PAD increases as a function of time since injury (TSI) and if injury severity and sex interacted to influence this progression.

METHODS

Through the ENIGMA Adult Moderate and Severe (AMS)-TBI working group, we examine the largest TBI sample to date (n = 343), along with controls, for a total sample size of n = 540, to replicate and extend prior findings in the study of TBI brain age. Cross-sectional T1w-MRI data were aggregated across 7 cohorts, and brain age was established using a similar brain age algorithm to prior work in TBI.

RESULTS

Findings show that PAD widens with longer TSI, and there was evidence for differences between sexes in PAD, with men showing more advanced brain age. We did not find strong evidence supporting a link between PAD and cognitive performance.

INTERPRETATION

This work provides evidence that changes in brain structure after cmsTBI are dynamic, with an initial period of change, followed by relative stability in brain morphometry, eventually leading to further changes in the decades after a single cmsTBI. ANN NEUROL 2024;96:365-377.

Improving quantitative susceptibility mapping for the identification of traumatic brain injury neurodegeneration at the individual level

BACKGROUND

Emerging evidence suggests that traumatic brain injury (TBI) is a major risk factor for developing neurodegenerative disease later in life. Quantitative susceptibility mapping (QSM) has been used by an increasing number of studies in investigations of pathophysiological changes in TBI. However, generating artefact-free quantitative susceptibility maps in brains with large focal lesions, as in the case of moderate-to-severe TBI (ms-TBI), is particularly challenging. To address this issue, we utilized a novel two-pass masking technique and reconstruction procedure (two-pass QSM) to generate quantitative susceptibility maps (QSMxT; Stewart et al., 2022, Magn Reson Med.) in combination with the recently developed virtual brain grafting (VBG) procedure for brain repair (Radwan et al., 2021, NeuroImage) to improve automated delineation of brain areas. We used QSMxT and VBG to generate personalised QSM profiles of individual patients with reference to a sample of healthy controls.

METHODS

Chronic ms-TBI patients (N = 8) and healthy controls (N = 12) underwent (multi-echo) GRE, and anatomical MRI (MPRAGE) on a 3T Siemens PRISMA scanner. We reconstructed the magnetic susceptibility maps using two-pass QSM from QSMxT. We then extracted values of magnetic susceptibility in grey matter (GM) regions (following brain repair via VBG) across the whole brain and determined if they deviate from a reference healthy control group [Z-score < -3.43 or > 3.43, relative to the control mean], with the aim of obtaining personalised QSM profiles.

RESULTS

Using two-pass QSM, we achieved susceptibility maps with a substantial increase in quality and reduction in artefacts irrespective of the presence of large focal lesions, compared to single-pass QSM. In addition, VBG minimised the loss of GM regions and exclusion of patients due to failures in the region delineation step. Our findings revealed deviations in magnetic susceptibility measures from the HC group that differed across individual TBI patients. These changes included both increases and decreases in magnetic susceptibility values in multiple GM regions across the brain.

CONCLUSIONS

We illustrate how to obtain magnetic susceptibility values at the individual level and to build personalised QSM profiles in ms-TBI patients. Our approach opens the door for QSM investigations in more severely injured patients. Such profiles are also critical to overcome the inherent heterogeneity of clinical populations, such as ms-TBI, and to characterize the underlying mechanisms of neurodegeneration at the individual level more precisely. Moreover, this new personalised QSM profiling could in the future assist clinicians in assessing recovery and formulating a neuroscience-guided integrative rehabilitation program tailored to individual TBI patients.

The bibliometric and altmetric analysis of chronic traumatic encephalopathy research: how great is the impact?

Background

The study of chronic traumatic encephalopathy (CTE) has received great attention from academia and the general public. This study aims to analyze the research productivity on CTE and investigate the most discussed articles in academia and the general public by conducting bibliometric and altmetric analyses.

Methods

Data of articles were obtained from the Web of Science Core Databases and Altmetric Explore. VOSviewer and CiteSpace software were used to analyze and visualize the articles. The correlation between Altmetric attention scores (AAS) and citation counts were assessed by Spearman correlation coefficient.

Results

788 publications of CTE were eventually gathered and analyzed, and 100 articles with highest citation counts (Top-cited) and 100 articles with highest AASs (Top-AAS) were then identified. The keywords density map showed both the general public and the scientists were particularly interested in the risk factors and pathology of CTE, and scientists were interested in the causes and characteristics of neurodegenerative diseases while the public became increasingly concerned about the detection and prevention of CTE. By examining the shared characteristics of the 44 articles (High-High articles) that overlapped between Top-cited and Top-AAS articles, we identified certain traits that may potentially contribute to their high citation rates and high AASs. Besides, significant positive correlations with varied strength between AAS and citation were observed in the 788 articles, Top-cited, Top-AAS and High-High datasets.

Conclusion

This study is the first to link bibliometric and altmetric analyses for CTE publications, which may provide deeper understanding of the attention of the scientists and the general public pay to the study of CTE, and offer some guidance and inspiration for future CTE in the selection of research topics and directions.

A multi-resolution TOF-DOI detector for human brain dedicated PET scanner

Objective. We propose a single-ended readout, multi-resolution detector design that can achieve high spatial, depth-of-interaction (DOI), and time-of-flight (TOF) resolutions, as well as high sensitivity for human brain-dedicated positron emission tomography (PET) scanners.Approach. The detector comprised two layers of LYSO crystal arrays and a lightguide in between. The top (gamma ray entrance) layer consisted of a 16 × 16 array of 1.53 × 1.53 × 6 mm3LYSO crystals for providing high spatial resolution. The bottom layer consisted of an 8 × 8 array of 3.0 × 3.0 × 15 mm3LYSO crystals that were one-to-one coupled to an 8 × 8 multipixel photon counter (MPPC) array for providing high TOF resolution. The 2 mm thick lightguide introduces inter-crystal light sharing that causes variations of the light distribution patterns for high DOI resolution. The detector was read out by a PETsys TOFPET2 application-specific integrated circuit.Main result. The top and bottom layers were distinguished by a convolutional neural network with 97% accuracy. All crystals in the top and bottom layers were resolved. The inter-crystal scatter (ICS) events in the bottom layer were identified, and the measured average DOI resolution of the bottom layer was 4.1 mm. The coincidence time resolution (CTR) for the top-top, top-bottom, and bottom-bottom coincidences was 476 ps, 405 ps, and 298 ps, respectively. When ICS events were excluded from the bottom layer, the CTR of the bottom-bottom coincidence was 277 ps.Significance. The top layer of the proposed two-layer detector achieved a high spatial resolution and the bottom layer achieved a high TOF resolution. Together with its high DOI resolution and detection efficiency, the proposed detector is well suited for next-generation high-performance brain-dedicated PET scanners.

Quantitative proteomic and phosphoproteomic analyses of the hippocampus reveal the involvement of NMDAR1 signaling in repetitive mild traumatic brain injury

The cumulative damage caused by repetitive mild traumatic brain injury can cause long-term neurodegeneration leading to cognitive impairment. This cognitive impairment is thought to result specifically from damage to the hippocampus. In this study, we detected cognitive impairment in mice 6 weeks after repetitive mild traumatic brain injury using the novel object recognition test and the Morris water maze test. Immunofluorescence staining showed that p-tau expression was increased in the hippocampus after repetitive mild traumatic brain injury. Golgi staining showed a significant decrease in the total density of neuronal dendritic spines in the hippocampus, as well as in the density of mature dendritic spines. To investigate the specific molecular mechanisms underlying cognitive impairment due to hippocampal damage, we performed proteomic and phosphoproteomic analyses of the hippocampus with and without repetitive mild traumatic brain injury. The differentially expressed proteins were mainly enriched in inflammation, immunity, and coagulation, suggesting that non-neuronal cells are involved in the pathological changes that occur in the hippocampus in the chronic stage after repetitive mild traumatic brain injury. In contrast, differentially expressed phosphorylated proteins were mainly enriched in pathways related to neuronal function and structure, which is more consistent with neurodegeneration. We identified N-methyl-D-aspartate receptor 1 as a hub molecule involved in the response to repetitive mild traumatic brain injury , and western blotting showed that, while N-methyl-D-aspartate receptor 1 expression was not altered in the hippocampus after repetitive mild traumatic brain injury, its phosphorylation level was significantly increased, which is consistent with the omics results. Administration of GRP78608, an N-methyl-D-aspartate receptor 1 antagonist, to the hippocampus markedly improved repetitive mild traumatic brain injury-induced cognitive impairment. In conclusion, our findings suggest that N-methyl-D-aspartate receptor 1 signaling in the hippocampus is involved in cognitive impairment in the chronic stage after repetitive mild traumatic brain injury and may be a potential target for intervention and treatment.

Sleep/Wake Disorders After Sports Concussion: Risks, Revelations, and Interventions

SUMMARY

Sleep-wake disturbances (SWDs) are among the most prevalent, persistent, and often disregarded sequelae of traumatic brain injury. Identification and treatment of SWDs in patients with traumatic brain injury is important and can complement other efforts to promote maximum functional recovery. SWDs can accentuate other consequences of traumatic brain injury, negatively affect mood, exacerbate pain, heighten irritability, and diminish cognitive abilities and the potential for recovery. The risk for sports injuries increases when athletes are sleep deprived. Sleep deprivation increases risk-taking behaviors, predisposing to injuries. SWDs are an independent risk factor for prolonged recovery after sports-related concussion. SWDs following sports-related concussion have been shown to impede recovery, rehabilitation, and return to preinjury activities.

A Molecular Toolbox of Positron Emission Tomography Tracers for General Anesthesia Mechanism Research

With appropriate radiotracers, positron emission tomography (PET) allows direct or indirect monitoring of the spatial and temporal distribution of anesthetics, neurotransmitters, and biomarkers, making it an indispensable tool for studying the general anesthesia mechanism. In this Perspective, PET tracers that have been recruited in general anesthesia research are introduced in the following order: 1) ¹¹C/¹⁸F-labeled anesthetics, i.e., PET tracers made from inhaled and intravenous anesthetics; 2) PET tracers targeting anesthesia-related receptors, e.g., neurotransmitters and voltage-gated ion channels; and 3) PET tracers for studying anesthesia-related neurophysiological effects and neurotoxicity. The radiosynthesis, pharmacodynamics, and pharmacokinetics of the above PET tracers are mainly discussed to provide a practical molecular toolbox for radiochemists, anesthesiologists, and those who are interested in general anesthesia.

Imaging glucose metabolism to reveal tumor progression

Purpose: To analyze and review the progress of glucose metabolism-based molecular imaging in detecting tumors to guide clinicians for new management strategies. Summary: When metabolic abnormalities occur, termed the Warburg effect, it simultaneously enables excessive cell proliferation and inhibits cell apoptosis. Molecular imaging technology combines molecular biology and cell probe technology to visualize, characterize, and quantify processes at cellular and subcellular levels in vivo. Modern instruments, including molecular biochemistry, data processing, nanotechnology, and image processing, use molecular probes to perform real-time, non-invasive imaging of molecular and cellular events in living organisms. Conclusion: Molecular imaging is a non-invasive method for live detection, dynamic observation, and quantitative assessment of tumor glucose metabolism. It enables in-depth examination of the connection between the tumor microenvironment and tumor growth, providing a reliable assessment technique for scientific and clinical research. This new technique will facilitate the translation of fundamental research into clinical practice.

Challenges in the pharmacological treatment of patients under suspicion of chronic traumatic encephalopathy: A review

Chronic traumatic encephalopathy (CTE) is caused by progressive neurodegeneration associated with repetitive head impacts. This disease is more common in professionals who practice contact sports, resulting in a concussion and subconcussive trauma. CTE is characterized by the accumulation of hyperphosphorylated tau protein in neurons, astrocytes, and frontotemporal lobe degeneration. Symptoms are usually nonspecific and overlap with other neurodegenerative diseases, such as Alzheimer's disease and frontotemporal dementia, making it difficult to provide drug treatment for patients with this comorbidity. Therefore, the objective of this article is to present an updated review of the pharmacological treatment of chronic traumatic encephalopathy and its challenges.

PET Imaging of Fructose Metabolism in a Rodent Model of Neuroinflammation with 6-[18F]fluoro-6-deoxy-D-fructose

Fluorine-18 labeled 6-fluoro-6-deoxy-D-fructose (6-[¹⁸F]FDF) targets the fructose-preferred facilitative hexose transporter GLUT5, which is expressed predominantly in brain microglia and activated in response to inflammatory stimuli. We hypothesize that 6-[¹⁸F]FDF will specifically image microglia following neuroinflammatory insult. 6-[¹⁸F]FDF and, for comparison, [¹⁸F]FDG were evaluated in unilateral intra-striatal lipopolysaccharide (LPS)-injected male and female rats (50 µg/animal) by longitudinal dynamic PET imaging in vivo. In LPS-injected rats, increased accumulation of 6-[¹⁸F]FDF was observed at 48 h post-LPS injection, with plateaued uptake (60-120 min) that was significantly higher in the ipsilateral vs. contralateral striatum (0.985 ± 0.047 and 0.819 ± 0.033 SUV, respectively; p = 0.002, n = 4M/3F). The ipsilateral-contralateral difference in striatal 6-[¹⁸F]FDF uptake expressed as binding potential (BP_SRTM) peaked at 48 h (0.19 ± 0.11) and was significantly decreased at one and two weeks. In contrast, increased [¹⁸F]FDG uptake in the ipsilateral striatum was highest at one week post-LPS injection (BP_SRTM = 0.25 ± 0.06, n = 4M). Iba-1 and GFAP immunohistochemistry confirmed LPS-induced activation of microglia and astrocytes, respectively, in ipsilateral striatum. This proof-of-concept study revealed an early response of 6-[¹⁸F]FDF to neuroinflammatory stimuli in rat brain. 6-[¹⁸F]FDF represents a potential PET radiotracer for imaging microglial GLUT5 density in brain with applications in neuroinflammatory and neurodegenerative diseases.

[Features of the patient management with traumatic brain injury]

The aim of our study was to consider features of pathogenesis, diagnosis and therapy of traumatic brain injury (TBI) from the viewpoint of neurologist. The mechanisms of emerging injury of the central nervous system, including neuro-inflammation and oxidative stress in patients with TBI, and correlations between clinical manifestations and severity of TBI are discussed. Special attention is paid to the description of certain TBI consequences, e.g. structural drug-resistant epilepsy and post-traumatic stress disorder. We provide evidence for difficulties and lesser availability of rehabilitation programs to patients with TBI during COVID-19 pandemics. One should mention a need for administration of Mexidol as the antioxidant/antihypoxant drug into complex therapy of TBI in such patients. In the period of COVID-19 pandemics, the role of neurologist in management of TBI patients still increases, especially, at the outpatient treatment stage, and when carrying out therapy and medical rehabilitation programs.

Systematic Review of the Long-Term Neuroimaging Correlates of Mild Traumatic Brain Injury and Repetitive Head Injuries

Objective: To systematically review the literature on the long-term neuroimaging findings (≥10 years from exposure) for exposure in adulthood to mild traumatic brain injury (mTBI) and repetitive head impacts (RHIs) using neuroimaging across all available populations. Data sources: Four electronic databases: MEDLINE, SPORTDiscus, PsycINFO, and EMBASE. Study selection: All articles were original research and published in English. Studies examined adults with remote exposure to mTBI and/or RHIs from ten or more years ago in addition to any associated neuroimaging findings. Data extraction: Parameters mainly included participants' population, age, years since head injury, race, sex, education level, and any neuroimaging findings. Scores for the level of evidence and risk of bias were calculated independently by two authors. Results: 5,521 studies were reviewed, of which 34 met inclusion criteria and were included in this study. The majority of adults in these studies showed positive neuroimaging findings one or more decades following mTBI/RHI exposure. This was consistent across study populations (i.e., veterans, athletes, and the general population). There was evidence for altered protein deposition patterns, micro- and macro-structural, functional, neurochemical, and blood flow-related differences in the brain for those with remote mTBI/RHI exposure. Conclusion: Findings from these studies suggest that past mTBI/RHI exposure may be associated with neuroimaging findings. However, given the methodological constraints related to relatively small sample sizes and the heterogeneity in injury types/exposure and imaging techniques used, conclusions drawn from this review are limited. Well-designed longitudinal studies with multimodal imaging and in-depth health and demographic information will be required to better understand the potential for having positive neuroimaging findings following remote mTBI/RHI.

Post-traumatic Neuroinflammation: Relevance to Pediatrics

Both detrimental and beneficial effects of post-traumatic neuroinflammation have become a major research focus as they offer the potential for immediate as well as delayed targeted reparative therapies. Understanding the complex interactions of central and peripheral immunocompetent cells as well as their mediators on brain injury and recovery is complicated by the temporal, regional, and developmental differences in their response to injuries. Microglia, the brain-resident macrophages, have become central in these investigations as they serve a major surveillance function, have the ability to react swiftly to injury, recruit various cellular and chemical mediators, and monitor the reparative/degenerative processes. In this review we describe selected aspects of this burgeoning literature, describing the critical role of cytokines and chemokines, microglia, advances in neuroimaging, genetics and fractal morphology analysis, our research efforts in this area, and selected aspects of pediatric post-traumatic neuroinflammation.

Alzheimer's disease neuropathology is exacerbated following traumatic brain injury. Neuroprotection by co-administration of nanowired mesenchymal stem cells and cerebrolysin with monoclonal antibodies to amyloid beta peptide

Military personnel are prone to traumatic brain injury (TBI) that is one of the risk factors in developing Alzheimer's disease (AD) at a later stage. TBI induces breakdown of the blood-brain barrier (BBB) to serum proteins into the brain and leads to extravasation of plasma amyloid beta peptide (ΑβP) into the brain fluid compartments causing AD brain pathology. Thus, there is a need to expand our knowledge on the role of TBI in AD. In addition, exploration of the novel roles of nanomedicine in AD and TBI for neuroprotection is the need of the hour. Since stem cells and neurotrophic factors play important roles in TBI and in AD, it is likely that nanodelivery of these agents exert superior neuroprotection in TBI induced exacerbation of AD brain pathology. In this review, these aspects are examined in details based on our own investigations in the light of current scientific literature in the field. Our observations show that TBI exacerbates AD brain pathology and TiO₂ nanowired delivery of mesenchymal stem cells together with cerebrolysin-a balanced composition of several neurotrophic factors and active peptide fragments, and monoclonal antibodies to amyloid beta protein thwarted the development of neuropathology following TBI in AD, not reported earlier.

Identifying degenerative effects of repetitive head trauma with neuroimaging: a clinically-oriented review

BACKGROUND AND SCOPE OF REVIEW

Varying severities and frequencies of head trauma may result in dynamic acute and chronic pathophysiologic responses in the brain. Heightened attention to long-term effects of head trauma, particularly repetitive head trauma, has sparked recent efforts to identify neuroimaging biomarkers of underlying disease processes. Imaging modalities like structural magnetic resonance imaging (MRI) and positron emission tomography (PET) are the most clinically applicable given their use in neurodegenerative disease diagnosis and differentiation. In recent years, researchers have targeted repetitive head trauma cohorts in hopes of identifying in vivo biomarkers for underlying biologic changes that might ultimately improve diagnosis of chronic traumatic encephalopathy (CTE) in living persons. These populations most often include collision sport athletes (e.g., American football, boxing) and military veterans with repetitive low-level blast exposure. We provide a clinically-oriented review of neuroimaging data from repetitive head trauma cohorts based on structural MRI, FDG-PET, Aβ-PET, and tau-PET. We supplement the review with two patient reports of neuropathology-confirmed, clinically impaired adults with prior repetitive head trauma who underwent structural MRI, FDG-PET, Aβ-PET, and tau-PET in addition to comprehensive clinical examinations before death.

REVIEW CONCLUSIONS

Group-level comparisons to controls without known head trauma have revealed inconsistent regional volume differences, with possible propensity for medial temporal, limbic, and subcortical (thalamus, corpus callosum) structures. Greater frequency and severity (i.e., length) of cavum septum pellucidum (CSP) is observed in repetitive head trauma cohorts compared to unexposed controls. It remains unclear whether CSP predicts a particular neurodegenerative process, but CSP presence should increase suspicion that clinical impairment is at least partly attributable to the individual's head trauma exposure (regardless of underlying disease). PET imaging similarly has not revealed a prototypical metabolic or molecular pattern associated with repetitive head trauma or predictive of CTE based on the most widely studied radiotracers. Given the range of clinical syndromes and neurodegenerative pathologies observed in a subset of adults with prior repetitive head trauma, structural MRI and PET imaging may still be useful for differential diagnosis (e.g., assessing suspected Alzheimer's disease).

An Update on the State of Tau Radiotracer Development: a Brief Review

Evolving scientific evidence has begun to point towards hyperphosphorylated tau as a major neurotoxic component in the pathophysiological development of many major neurodegenerative conditions. In response to a need for accurate and reliable diagnosis and disease monitoring in clinical and trial settings, there has been great effort put into the development of tau radiotracers. While first-generation and second-generation radiotracers have provided a basis for assessing tau, concerns of inadequate specificity and selectivity have continued to motivate further study of these radiotracers and the development of novel radiopharmaceuticals. Given the prospective scientific and clinical value of a valid tau radiotracer, the molecular neuroimaging community must be aware of the most recent developments in the realm of tau radiotracer development. This brief review article will critically overview the most established tau radiotracers and, most importantly, concentrate on the progress of more recently developed tau radiotracers.

Iron Metabolism Disorders for Cognitive Dysfunction After Mild Traumatic Brain Injury

Traumatic brain injury (TBI) is one of the most harmful forms of acute brain injury and predicted to be one of the three major neurological diseases that cause neurological disabilities by 2030. A series of secondary injury cascades often cause cognitive dysfunction of TBI patients leading to poor prognosis. However, there are still no effective intervention measures, which drive us to explore new therapeutic targets. In this process, the most part of mild traumatic brain injury (mTBI) is ignored because its initial symptoms seemed not serious. Unfortunately, the ignored mTBI accounts for 80% of the total TBI, and a large part of the patients have long-term cognitive dysfunction. Iron deposition has been observed in mTBI patients and accompanies the whole pathological process. Iron accumulation may affect long-term cognitive dysfunction from three pathways: local injury, iron deposition induces tau phosphorylation, the formation of neurofibrillary tangles; neural cells death; and neural network damage, iron deposition leads to axonal injury by utilizing the iron sensibility of oligodendrocytes. Thus, iron overload and metabolism dysfunction was thought to play a pivotal role in mTBI pathophysiology. Cerebrospinal fluid-contacting neurons (CSF-cNs) located in the ependyma have bidirectional communication function between cerebral-spinal fluid and brain parenchyma, and may participate in the pathway of iron-induced cognitive dysfunction through projected nerve fibers and transmitted factor, such as 5-hydroxytryptamine, etc. The present review provides an overview of the metabolism and function of iron in mTBI, and to seek a potential new treatment target for mTBI with a novel perspective through combined iron and CSF-cNs.

Spatial Patterns of Amyloid Deposition in Patients with Chronic Focal or Diffuse Traumatic Brain Injury Using 18F-FPYBF-2 PET

AIM

Amyloid-β (Aβ) accumulation, accelerated by traumatic brain injury (TBI), may play a crucial role in neurodegeneration in chronic-stage TBI. The injury type could influence Aβ dynamics because of TBI's complex, heterogeneous nature. We, therefore, investigated spatial patterns of amyloid deposition according to injury type after TBI using 5-(5-(2-(2-(2-[F]-fluoroethoxy)ethoxy)ethoxy)benzofuran-2-yl)-N-methylpyridin-2-amine (¹⁸F-FPYBF-2) positron emission tomography (PET).

METHODS

Altogether, 20 patients with chronic TBI [12 with focal injury, 8 with diffuse axonal injury (DAI)] underwent ¹⁸F-FPYBF-2 PET, structural magnetic resonance imaging (MRI), and neuropsychological examination. Additionally, 50 healthy controls underwent either ¹⁸F-FPYBF-2 PET (n=30) or structural MRI (n=20).

RESULTS

Standardized uptake value ratio (SUVR) on PET images and regional brain volumes were measured in four cortical (frontal, parietal, occipital, temporal) and subcortical (combined caudate, putamen, pallidum, thalamus) regions. Patients with DAI showed significantly increased (compared with controls) SUVR in occipital and temporal cortices and decreased brain volume in occipital cortex (corrected p < 0.05). Although patients with focal injury showed decreased SUVR in all regions except occipital cortex, there were no significant differences (compared with controls) in the SUVR in any regions. There were no significant correlations between increased SUVR and neuropsychological impairments in patients with DAI.

CONCLUSION

Varying spatial patterns of amyloid deposition suggest amyloid pathology diversity depending on the injury type in chronic-TBI patients.