Small Brain Research Articles

A historical perspective on the insect central complex: Anatomy, development, and function

The central complex (CX), a remarkable brain region at the core of insect behaviors, has been the subject of extensive research for decades. In this review, we offer a comprehensive historical perspective on the anatomy, development, and function of the CX. The CX consists of discrete and highly structured neuropils found at the center of the brain, which are conserved across insects and arthropods. The developmental processes that shape the CX are themselves conserved across insects. In early research, the CX had been shown to receive visual information and control motor function. Using increasingly advanced methods throughout the years, it has become clear that the CX is involved in high-level behavioral control, such as in vector navigation and goal directed orientation. Its numerical simplicity presents a rare opportunity to study structure-function relationships in small brains, gain insights into evolutionary neurobiology, and develop novel neuromorphic technologies inspired by insect brains. Since the CX is a highly conserved brain region involved in the control of spatial tasks, it is uniquely suited to gain a detailed understanding of the computations required for these processes at the level of neural circuits.

Investigation of the Development and Evolution of the Mammalian Cerebrum using Gyrencephalic Ferrets

Mammalian brains have evolved a neocortex, which has diverged in size and morphology in different species over the course of evolution. In some mammals, a substantial increase in the number of neurons and glial cells resulted in the expansion and folding of the cerebrum, and it is believed that these evolutionary changes contributed to the acquisition of higher cognitive abilities in mammals. However, their underlying molecular and cellular mechanisms remain insufficiently elucidated. A major difficulty in addressing these mechanisms stemmed from the lack of appropriate animal models, as conventional experimental animals such as mice and rats have small brains without structurally obvious folds. Therefore, researchers including us have focused on using ferrets instead of mice and rats. Ferrets are domesticated carnivorous mammals with a gyrencephalic cerebrum, and, notably, they are amenable to genetic manipulations including in utero electroporation to knock out genes in the cerebrum. In this review, we highlight recent research into the mechanisms underlying the development and evolution of cortical folds using ferrets.

Detection of Small Brain Metastases by 18F-Thretide PET/CT in Clear Cell Renal Cell Carcinoma.

A 46-year-old woman with a history of radical nephrectomy for clear cell renal cell carcinoma underwent 18F-FDG and 18F-Thretid (also known as Al18F-PSMA-BCH) PET/CT. Although the 18F-FDG PET/CT failed to detect any brain metastases, the 18F-Thretide PET/CT revealed 2 small metastases: one measuring 1.0 × 0.7 cm in the right cerebellum and the other measuring 0.4 cm in the right frontal lobe. These metastatic lesions were subsequently confirmed by brain MRI.

Congenital Cytomegalovirus Infection: Update on Screening, Diagnosis and Treatment: Scientific Impact Paper No. 56.

Cytomegalovirus (CMV) is the most common cause of viral infection in newborn babies, and affects 1 in 200 of all live born infants in high-income countries; and 1 in 71 in low- and middle-income countries. It is a major cause of hearing loss and brain damage. Women may get CMV infection for the first time during pregnancy (primary infection) or may experience 'non-primary' infection, either by reactivation of previous CMV infection or by a new infection with a different strain of the virus. The most common source of infection to pregnant women is the saliva and urine of young children. Therefore, all pregnant women, especially those in regular contact with young children, should be informed about hygiene-based measures to reduce the risks, e.g. handwashing. The UK National Screening Committee recommends against universal antenatal or newborn screening for CMV. Testing for CMV is usually offered only to women who develop symptoms of influenza, glandular fever or hepatitis (liver inflammation) during pregnancy, or for those whom a routine ultrasound scan detects fetal anomalies that suggests possible CMV infection. The risk of harm to the fetus is greatest following primary CMV infection of the woman in early pregnancy, and appears to be very low following infection after 12 weeks of pregnancy. Babies with CMV infection at birth may have jaundice, a rash, enlarged liver or spleen, a small brain, or be small for their gestational age. Around 1 in 8 babies born with CMV infection will have clinically detectable signs at birth. The rest will not have any features detectable by clinical examination alone. Therefore, all infants with CMV infection at birth should be followed up at a minimum of up to 2 years of age or later, depending upon the disease status, to check hearing and brain development. Following primary CMV infection in the first 12 weeks of pregnancy, if the woman starts taking the antiviral medicine valaciclovir (valacyclovir) it reduces the risk of the baby becoming infected. Where CMV infection of the fetus in the womb has been confirmed (by amniocentesis, for example), regular ultrasound scans should be offered every 2-3 weeks until birth. Detailed assessment of the fetal brain is an essential part of these scans. Where maternal CMV infection occurs, but fetal infection is not confirmed, repeated ultrasound scans of the fetus should be offered every 2-3 weeks until birth. In infected fetuses, as well as ultrasound scans, an MRI scan of the brain should be offered at 28-32 weeks of gestation (and sometimes repeated 3-4 weeks later) to assess for any signs of harm to the fetal brain. All babies born to women with confirmed or suspected CMV infection should be tested for CMV with a urine or saliva sample within the first 21 days of life. In newborns with symptomatic CMV infection at birth, treatment with antiviral medicine (valganciclovir or ganciclovir) can reduce hearing loss in 5 out of 6 babies, and improve long-term brain development outcomes in some. There is no licensed vaccine for CMV.

The brain of Myotragus balearicus, an insular bovid from the Balearics

ABSTRACT Myotragus balearicus is the terminal species of a Caprinae lineage that inhabited the Balearic Islands since the Messinian. Myotragus balearicus had a relatively small brain, reported to be half the size of a contemporary bovid of similar size. This study presents a reassessment of its brain size and anatomy. We demonstrate that the brain of M. balearicus is only 17% smaller when compared to Late Miocene taxa. Since the ancestors of M. balearicus were isolated on the Balearics in the Late Miocene, we deduce that the small brain size of M. balearicus is a feature largely retained from its continental ancestor and only partially the result of geographic isolation. The reduction in brain size can be attributed to reduction of the occipital region. We hypothesise that neuroanatomical changes during the evolutionary process of dwarfism were likely influenced by the absence of ecologically relevant predators.

Adding immune checkpoint inhibitors to chemotherapy confers modest survival benefit in patients with small cell lung cancer and brain metastases: a retrospective analysis.

Brain metastases (BM) are highly prevalent and associated with a poor prognosis in patients with small cell lung cancer (SCLC). However, the evidence regarding the efficacy of immune checkpoint inhibitors (ICIs) in combination with chemotherapy for patients with SCLC and BM remains limited. Therefore, the objective of this study is to evaluate whether the addition of ICIs confers survival benefits for patients with SCLC and BM. This retrospective study enrolled patients with SCLC and BM at the Sun Yat-sen University Cancer Center between January 2018 and December 2022. Clinical characteristics were extracted from medical records. Depending on whether ICIs were added to the first-line treatment, the patients were categorized into the chemotherapy group and the chemoimmunotherapy group. The efficacy of these two treatment approaches was analyzed and compared. A total of 165 patients were enrolled, with 85 in the chemotherapy group and 80 in the chemoimmunotherapy group. The chemoimmunotherapy group showed a tendency towards prolonged intracranial [6.6 vs. 5.9 months, hazard ratio (HR) =0.77; P=0.14] and extracranial (6.9 vs. 6.5 months, HR =0.73; P=0.12) progression-free survival (PFS) and overall survival (OS) (15.6 vs. 14.5 months, HR =0.98; P=0.93) compared to the chemotherapy group. Cox regression analysis identified liver metastases and local treatment for BM as independent prognostic factors for OS in patients. Furthermore, the chemotherapy group and the chemoimmunotherapy group demonstrated similar patterns of initial disease progression. Adding ICIs to chemotherapy confers modest survival benefits in patients with SCLC and BM.

RFC2 may contribute to the pathogenicity of Williams syndrome revealed in a zebrafish model

Williams syndrome (WS) is a rare multisystemic disorder caused by recurrent microdeletions on 7q11.23, characterized by intellectual disability, distinctive craniofacial and dental features, and cardiovascular problems. Previous studies have explored the roles of individual genes within these microdeletions in contributing to WS phenotypes. Here, we report five patients with WS with 1.4 Mb–1.5 Mb microdeletions that include RFC2, as well as one patient with a 167 kb microdeletion involving RFC2 and six patients with intragenic variants within RFC2. To investigate the potential involvement of RFC2 in WS pathogenicity, we generate a rfc2 knockout (KO) zebrafish using CRISPR-Cas9 technology. Additionally, we generate a KO zebrafish of its paralog gene, rfc5, to better understand the functions of these RFC genes in development and disease. Both rfc2 and rfc5 KO zebrafish exhibit similar phenotypes reminiscent of WS, including small head and brain, jaw and dental defects, and vascular problems. RNA-seq analysis reveals that genes associated with neural cell survival and differentiation are specifically affected in rfc2 KO zebrafish. In addition, heterozygous rfc2 KO adult zebrafish demonstrate an anxiety-like behavior with increased social cohesion. These results suggest that RFC2 may contribute to the pathogenicity of Williams syndrome, as evidenced by the zebrafish model.

Immunogenicity analysis based on VP1 and VP2 proteins of bovine enterovirus

Bovine enterovirus (BEV) infection manifests as a spectrum of clinical signs affecting the respiratory, gastrointestinal, and reproductive systems in cattle. Outbreaks of this disease results in large economic losses to the bovine industry worldwide. Currently there are no efficacious vaccines and medicines to prevent BEV infection. In the present study, reverse transcription-polymerase chain reaction was used to amplify the VP1 and VP2 genes of BEV, enabling the synthesis of a chimeric recombinant protein which contained partial sequences from both proteins. Subsequently, the emulsified purified proteins with Freund’s adjuvant were used for triple-fold immunization of 4-week-old Institute of Cancer Research (ICR) mice. The mice were subsequently subjected to a challenge assay which elicited an immune response that was characterized by elevated titers of BEV-specific neutralizing antibodies. Notably, the results showed that the purification of pET32a-VP1 and pET32a-VP2 proteins markedly curtailed virus excretion and mitigated the histopathological damage usually associated with BEV infections. These were observed in the small intestines, kidneys and brain in infected animals. It also alleviated clinical symptoms such as hypothermia and weight loss. In summary, this study offers a theoretical and practical basis for BEV vaccine development.

Folk games as a tool of formation of artistic and creative competence of primary school children in music classes

The article describes the features of acquiring artistic and creative competence, as a child's elementary awareness of the specifics of art forms (artistic and productive, musical, theatrical); valuable attitude to art and artistic activity, the desire to perceive folklore art. Folkloric forms of the heritage of Ukrainian culture are considered. Teaching and methodical material and practical recommendations are offered, which in music classes will be useful both to experienced teachers of preschool institutions and to those workers who are starting to work with the smallest brains. Normative documents in the field of preschool education were studied and play competence was considered as a child's ability to free, emotionally saturated, spontaneous activity on his/her own initiative, in which the possibility of applying existing and assimilating new knowledge and personal development is realized due to the child's desire to participate in the life of adults through the realization of interests in game and role-playing actions in a generalized form. The necessity of using folk games for the formation of artistic and creative competence in preschool children is substantiated. Peculiarities of knowledge of the surrounding world of preschool children and themselves in it are determined. The work proposes to create a basis for the natural formation and development of musical abilities in preschoolers through a folk game by encouraging children to play folk games. It has been emphasized that raising children is based on love and respect for Ukrainian musical folklore. The secrets of conducting music classes using folk games and working with preschoolers are recommended to teachers of primary schools, music teachers, teachers of children's vocal ensembles of extracurricular and club institutions, scientists, graduate students, students of pedagogical and art educational institutions, parents and the general public

Simple biomarkers to distinguish Parkinson's disease from its mimics in clinical practice: a comprehensive review and future directions.

In the last few years, a plethora of biomarkers have been proposed for the differentiation of Parkinson's disease (PD) from its mimics. Most of them consist of complex measures, often based on expensive technology, not easily employed outside research centers. MRI measures have been widely used to differentiate between PD and other parkinsonism. However, these measurements were often performed manually on small brain areas in small patient cohorts with intra- and inter-rater variability. The aim of the current review is to provide a comprehensive and updated overview of the literature on biomarkers commonly used to differentiate PD from its mimics (including parkinsonism and tremor syndromes), focusing on parameters derived by simple qualitative or quantitative measurements that can be used in routine practice. Several electrophysiological, sonographic and MRI biomarkers have shown promising results, including the blink-reflex recovery cycle, tremor analysis, sonographic or MRI assessment of substantia nigra, and several qualitative MRI signs or simple linear measures to be directly performed on MR images. The most significant issue is that most studies have been conducted on small patient cohorts from a single center, with limited reproducibility of the findings. Future studies should be carried out on larger international cohorts of patients to ensure generalizability. Moreover, research on simple biomarkers should seek measurements to differentiate patients with different diseases but similar clinical phenotypes, distinguish subtypes of the same disease, assess disease progression, and correlate biomarkers with pathological data. An even more important goal would be to predict the disease in the preclinical phase.

Brain energy metabolism as an underlying basis of slow and fast cognitive phenotypes in honeybees.

In the context of slow-fast behavioral variation, fast individuals are hypothesized to be those who prioritize speed over accuracy while slow individuals are those which do the opposite. Since energy metabolism is a critical component of neural and cognitive functioning, this predicts such differences in cognitive style to be reflected at the level of the brain. We tested this idea in honeybees by first classifying individuals into slow and fast cognitive phenotypes based on a learning assay and then measuring their brain respiration with high-resolution respirometry. Our results broadly show that inter-individual differences in cognition are reflected in differences in brain mass and accompanying energy use at the level of the brain and the whole animal. Larger brains had lower mass-specific energy usage and bees with larger brains had a higher metabolic rate. These differences in brain respiration and brain mass were, in turn, associated with cognitive differences, such that bees with larger brains were fast cognitive phenotypes whereas those with smaller brains were slow cognitive phenotypes. We discuss these results in the context of the role of energy in brain functioning and slow-fast decision making and speed accuracy trade-off.

Enhancing outcomes in extensive-stage small cell lung cancer brain metastases: a retrospective study on the synergistic effects of immune checkpoint inhibitor, brain radiotherapy, and chemotherapy.

Brain metastasis is a frequent complication in small cell lung cancer (SCLC), and there is an urgent need for new treatment modalities, given the limited success of traditional approaches. This study evaluates the combined efficacy and safety of brain radiotherapy (BRT), chemotherapy, and immune checkpoint inhibitors (ICIs) in the treatment of brain metastases in patients with extensive-stage SCLC (ES-SCLC). Additionally, it seeks to identify prognostic factors in these cases. A retrospective analysis was performed on 187 patients with ES-SCLC and brain metastases treated at Zhejiang Cancer Hospital from January 2017 to October 2023. Patients were divided into three groups based on their initial treatment: BRT alone, ICI alone, and a combined ICI + BRT approach, with chemotherapy included in all regimens. Variables such as age, number of brain metastases, symptoms, comorbidities, Karnofsky Performance Status (KPS) scores, smoking history, Graded Prognostic Assessment (GPA) scores, survival time, and treatment-related adverse events (TRAEs), including hematologic and hepatic toxicities were evaluated. Prognostic factors were assessed using univariate and multivariate analyses via Cox's proportional hazards model. The study also compared outcomes and TRAEs between patients undergoing synchronous treatment (ICI and BRT within four weeks) versus those with asynchronous therapy (more than four weeks apart). Median overall survival (OS) times differed significantly across the groups: 11.6 months for BRT, 11.6 months for ICI, and 20.9 months for ICI + BRT (P<0.001). The ICI + BRT group also exhibited notably better progression-free survival (PFS) and intracranial PFS (iPFS), with medians of 12.6 and 14.9 months, respectively (P<0.001). This group demonstrated significantly improved systemic and intracranial objective response rates (ORR) and disease control rates (DCR). No significant differences in acute radiation injury rates were observed between the BRT and ICI + BRT groups. Multivariate analysis identified several factors influencing OS, including treatment regimen, number of chemotherapy and ICI cycles, presence of bone and multiple brain metastases, and antiangiogenesis therapies and extracranial radiotherapy. Both atezolizumab and serplulimab ICIs, in combination with various radiotherapy regimens [whole BRT (WBRT), WBRT with boost], were effective. Notably, asynchronous ICI and BRT treatment demonstrated advantages in PFS and iPFS over concurrent therapy, with no significant differences in other therapeutic indices or TRAE incidence rates. For ES-SCLC patients with synchronous brain metastases, combined ICI and BRT, alongside chemotherapy, surpasses the efficacy of either treatment alone with manageable TRAEs. Importantly, asynchronous ICI and BRT therapy showed superior outcomes compared to synchronous treatment modalities.

Abstract 22: Evaluation of the effects of CD8 knock-out on cognitive decline in the TAC-induced hypertension mouse model

Hypertension is one of the main risk factors for cognitive impairment and dementia. We and others demonstrated the role of immunoinflammatory challenges in the establishment of cerebral injury following hypertension, highlighting a major role of inflammatory cytokines as interferon-gamma (IFN-γ) and finding increased parenchymal infiltration of CD8+ T cells. To establish the mechanistic role of these cells in cognitive impairment we subjected mice lacking CD8 cells (CD8 KO) and matched controls to aortic coarctation (TAC) and performed advanced neuroimaging analyses with a dedicated 7T small animal MRI, evaluating perfusion, brain volumes, and white matter microstructural integrity. Cognitive performance was evaluated at 4 weeks using the Morris Water Maze (MWM) test. Brain perfusion analyses shown protection from cerebral hypoperfusion in TAC CD8 KO mice compared to TAC WT mice (TAC WT vs TAC KO: 108 vs 148 ml/100g/min, p=0.0298) (Figure A). CD8 KO show preserved microstructural structure at DTI MRI, a typical trait of cerebral injury in clinical and experimental hypertension (Fimbria Fractional Anisotropy, TAC WT vs TAC KO: 0.45 vs 0.54, p=0.0210) , and show no a preserved cognition at MWM (Figure B), with a preserved learning curve at acquisition trial and a preserved memory retention capability evidenced at the probe trial (TAC WT vs TAC KO: 16,4 vs 32.2 seconds spent in platform quadrant, p=0.0014). The rescue from cerebral injury evidenced at MRI and the absence of cognitive impairment in CD8 KO mice demonstrate the pivotal role of CD8+ lymphocytes in the pathogenesis of hypertension-induced cognitive impairment.

Eje hipotálamo-hipofisario. Regulación neurohormonal, implicaciones patológicas, pruebas funcionales hipofisarias, indicaciones e interpretación

The hypothalamic-pituitary axis is a crucial system for maintaining homeostasis by integrating hormonal and neuronal inputs and outputs. Almost all bodily functions are regulated directly or indirectly by this axis. The hypothalamus, a small but vital brain region, monitors various inputs and maintains physiological set points through hormonal secretion, coordinating with the pituitary gland. This regulation involves multiple feedback mechanisms and interactions with other brain areas.The hypothalamus is anatomically divided into several regions and nuclei, each with specific functions. It produces a variety of hormones, including growth hormone-releasing hormone, corticotropin-releasing hormone, thyrotropin-releasing hormone, and gonadotropin-releasing hormone. These hormones regulate the secretion of corresponding hormones from the anterior pituitary gland, which control several physiological processes, including growth, metabolism, reproduction, and stress response.Pathological implications of hypothalamic-pituitary axis dysfunctions include endocrine disorders such as hyperprolactinemia, growth hormone deficiency, and hypogonadism. In addition, hypothalamic damage can lead to neurological and behavioral problems such as sleep disturbances and thermoregulation.

Inhibition of P-Glycoprotein Asymmetrically Alters the In Vivo Exposure Profile of SGC003F: A Novel Guanylate Cyclase Stimulator.

As a novel guanylate cyclase stimulator, SGC003F is being developed for the treatment of heart failure with a reduced ejection fraction (HFrEF). This study aimed to assess the effect of P-glycoprotein (P-gp) inhibition on SGC003F exposure in vivo, comparing plasma and tissue levels, and evaluating the role of P-gp in the small intestine, blood-brain barrier (BBB), and kidney in impacting the tissue exposure. Tariquidar, a P-gp inhibitor, was added to monolayer transport assays to observe the changes in the transmembrane characteristics of SGC003F. Rats were given SGC003F with tariquidar via various routes to measure plasma, tissue, urine, and fecal concentrations. The inclusion of tariquidar significantly altered the pharmacokinetics of SGC003F. In LLC-PK1-MDR1 cells, tariquidar reduced the efflux ratio of SGC003F from 6.56 to 1.28. In rats, it enhanced the plasma AUC by 3.05 or 1.61 times, increased the Cmax by 2.13 or 1.07 times, and notably improved bioavailability from 46.4% to 95%. Additionally, co-administration with tariquidar led to a decrease in fecal excretion and an increase in tissue exposure, with only a moderate effect on the partition ratios in the small intestine and brain. P-gp inhibition impacts SGC003F exposure, with plasma levels not fully reflecting tissue levels. P-gp in the small intestine and BBB affects SGC003F's pharmacokinetics, warranting further clinical drug-drug interaction (DDI) studies.

Small animal brain surgery with neither a brain atlas nor a stereotaxic frame

BackgroundStereotaxic surgery is a cornerstone in brain research for the precise positioning of electrodes and probes, but its application is limited to species with available brain atlases and tailored stereotaxic frames. Addressing this limitation, we introduce an alternative technique for small animal brain surgery that requires neither an aligned brain atlas nor a stereotaxic frame. New methodThe new method requires an ex-vivo high-contrast MRI brain scan of one specimen and access to a micro-CT scanner. The process involves attaching miniature markers to the skull, followed by CT scanning of the head. Subsequently, MRI and CT images are co-registered using standard image processing software and the targets for brain recordings are marked in the MRI image. During surgery, the animal's head is stabilized in any convenient orientation, and the probe’s 3D position and angle are tracked using a multi-camera system. We have developed a software that utilizes the on-skull markers as fiducial points to align the CT/MRI 3D model with the surgical positioning system, and in turn instructs the surgeon how to move the probe to reach the targets within the brain. ResultsOur technique allows the execution of insertion tracks connecting two points in the brain. We successfully applied this method for neuropixels probe positioning in owls, quails, and mice, demonstrating its versatility. Comparison with existing methodsWe present an alternative to traditional stereotaxic brain surgeries that does not require established stereotaxic tools. Thus, this method is especially of advantage for research in non-standard and novel animal models.

Seizures in small brains

Neonatal seizures are the most common neurological emergency in newborns; often signalling significant neurological dysfunction. Their pathophysiology is complex and relates to the imbalance between excitatory and inhibitory neurotransmitters in the immature brain. During the neonatal period, excitatory circuits mediated via neuro-transmitters like glutamate predominate while inhibitory circuits mediated via gamma-aminobutyric acid (GABA) signalling are underdeveloped. Additionally, immature ion channels, such as sodium, chloride, potassium, and calcium, increase neuronal excitability. The most common aetiology of seizures is attributed to neonatal hypoxic cerebral injury. However, metabolic vulnerabilities, such as hypoglycaemia and electrolyte imbalances, can also precipitate seizures. Identifying the underlying cause, which in a large majority is acute symptomatic, is critical for prompt treatment. Early intervention is essential to prevent long-term neurodevelopmental consequences.Diagnosing neonatal seizures is challenging due to their subtle presentations. Distinguishing them from non-seizure events is crucial. Accurate diagnosis is essential for appropriate treatment and management. Continuous electroencephalography (cEEG) is the gold standard for diagnosis, but an amplitude-integrated EEG (aEEG) is a useful alternative tool in neonatal intensive care units (NICUs), for high-risk infants. This facilitates diagnosis of electroclinical as well as electrical seizures; commonly encountered in the very sick newborns and those born prematurely. Neuroimaging, like magnetic resonance imaging (MRI) and computed tomography (CT) is required to identify structural causes, while laboratory and genetic tests check for infectious, metabolic and genetic aetiologies. The new classification proposed by the International League Against Epilepsy (ILAE), underscores the importance of recognition of electrical seizures and highlights the value of recognising the seizure semiology for the diagnosis of the underlying aetiology.

Imaging arterial and venous vessels using Iron Dextran enhanced multi-echo 3D gradient echo MRI at 7T.

Iron Dextran is a widely used iron oxide compound to treat iron-deficiency anemia patients in the clinic. Similar to other iron oxide compounds such as Ferumoxytol, it can also be used off-label as an intravascular magnetic resonance imaging (MRI) contrast agent due to its strong iron-induced T2 and T2* shortening effects. In this study, we seek to evaluate the feasibility of using Iron Dextran enhanced multi-echo susceptibility weighted imaging (SWI) MRI at 7T to image arterial and venous blood vessels in the human brain. Phantom experiments were performed to measure the r2* relaxivity for Iron Dextran in blood, based on which the SWI sequence was optimized. Pre- and post-infusion MR images were acquired in human subjects from which maps of arteries and veins were extracted. The post-contrast SWI images showed enhanced susceptibility difference between blood and the surrounding tissue in both arteries and veins. Our results showed that the proposed Iron Dextran enhanced multi-echo SWI approach allowed the visualization of blood vessels with diameters down to ~100 μm, including small blood vessels supplying and draining small brain structures such as the hippocampus. We conclude that Iron Dextran can be an alternative iron-based MRI contrast agent for blood vessel imaging in the human brain.

Ischemic core detection threshold of computed tomography perfusion (CTP) in acute stroke.

This study aimed to determine the accuracy of detecting ischemic core volume using computed tomography perfusion (CTP) in patients with suspected acute ischemic stroke compared to diffusion-weighted magnetic resonance imaging (DW-MRI) as the reference standard. This retrospective monocentric study included patients who underwent CTP and DW-MRI for suspected acute ischemic stroke. The ischemic core size was measured at DW-MRI. The detectability threshold volume was defined as the lowest volume detected by each method. Clinical data on revascularization therapy, along with the clinical decision that influenced the choice, were collected. Volumes of the ischemic cores were compared using the Mann-Whitney U test. Of 83 patients who underwent CTP, 52 patients (median age 73years, IQR 63-80, 36 men) also had DW-MRI and were included, with a total of 70 ischemic cores. Regarding ischemic cores, only 18/70 (26%) were detected by both CTP and DW-MRI, while 52/70 (74%) were detected only by DW-MRI. The median volume of the 52 ischemic cores undetected on CTP (0.6mL, IQR 0.2-1.3mL) was significantly lower (p < 0.001) than that of the 18 ischemic cores detected on CTP (14.2mL, IQR 7.0-18.4mL). The smallest ischemic core detected on CTP had a volume of 5.0mL. Among the 20 patients with undetected ischemic core on CTP, only 10% (2/20) received thrombolysis treatment. CTP maps failed in detecting ischemic cores smaller than 5mL. DW-MRI remains essential for suspected small ischemic brain lesions to guide a correct treatment decision-making.

Comparative effectiveness of frame-based and mask-based Gamma Knife stereotactic radiosurgery in brain metastases: A 509 patient meta-analysis.

Stereotactic Radiosurgery (SRS) is the primary treatment for patients with limited numbers of small brain metastases. Head fixation is usually performed with framed-based (FB) fixation; however, mask-based (MB) fixation has emerged as a less invasive alternative. A comparative meta-analysis between both approaches has not been performed. Databases were searched until August 28th, 2023, to identify studies comparing MB and FB SRS in the treatment of brain metastases. Our outcomes of interest included local tumor control (LTC), radiation necrosis (RN), mortality, and treatment time (TT). Mean difference (MD), risk ratio (RR), and hazard ratio (HR) were used for statistical comparisons. From 295 articles initially identified, six studies (1 clinical trial) involving 509 patients were included. LTC revealed comparable RR at 6-months (RR = 0.95[95%CI = 0.89-1.01], p = 0.12) and a marginal benefit in FB SRS at 1-year (RR = 0.87[95%CI = 0.78-0.96], p = 0.005). However, in oligometastases exclusively treated with single-fraction SRS, LTC was similar among groups (RR = 0.92 [95%CI = 0.89-1.0], p = 0.30). Similarly, in patients with oligometastases treated with single-fraction SRS, RN (HR = 1.69; 95%CI = 0.72-3.97, p = 0.22), TT (MD = -29.64; 95%CI = -80.38-21.10, p = 0.25), and mortality were similar among groups (RR = 0.62; 95%CI = 0.22-1.76, p = 0.37). Our findings suggest that FB and MB SRS, particularly oligometastases treated with single-fraction, are comparable in terms of LTC, RN, TT, and mortality. Further research is essential to draw definitive conclusions.