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According to Hamilton’s Selfish Herd Theory, a crucial survival benefit of group living is that it provides a ‘risk dilution’ function against predation. Despite a large literature on group living benefits in animals, few studies have been conducted on how group size alters subjective fear or threat perception in humans, and on what factors drive preferences for being in groups when facing threats. We conducted seven experiments (N=3,838) to test (A) if the presence of others decreases perception of threat under a variety of conditions. In studies 1 to 3, we experimentally manipulated group size in hypothetical and real-world situations, to show that fear responses decreased as group size increased. In studies 4 to 7 we again used a combination of hypothetical, virtual and real-world decisions to test (B) how internal states (e.g. anxiety) and external factors (e.g. threat level, availability of help) affected participants’ preference for groups. Participants consistently chose larger groups when threat and anxiety were high. Overall, our findings show that group size provides a salient signal of protection and safety.

Osteogenesis Imperfecta is a genetic disorder of increased bone fragility and low bone mass. Most cases are caused by a mutation in one of the two genes coding for the type I collagen protein. The correct clinical diagnosis of OI can be difficult sometimes, because of the wide phenotypic range. Therefore collagen I genes mutation identification can be helpful. We screened 23 patients by direct sequencing of the exons encoding the collagen protein. We identified 18 different mutations, while 5 cases were negative because of an uncertain clinical diagnosis or an atypical form of OI not related to collagen I genes. The current medical and pharmaceutical treatments are only symptomatic and do not alter the course of collagen mutations. Cells and gene therapies as potential treatments for OI have therefore to be actively investigated.

Thallium-201 is clinically used for the assessment of primary and recurrent brain tumors. The biologic properties of 201Tl that allow it to accumulate within the tumor cells render 201Tl useful in evaluating tumor malignancy, but its physical characteristics and nonroutine availability limits its use in some institutions, as compared to 99mTc-labeled compounds. The aim of this study was to assess the feasibility of using 99mTc-tetrofosmin for imaging brain tumors and to compare its uptake with that of 201Tl. METHODS: Twenty-six patients with 27 intracranial masses were studied with SPECT. In the first group of seven patients (Group A), the timing for optimal acquisition of the 99mTc-tetrofosmin scan was assessed. In the second group of 19 patients (Group B), two sequential 201Tl (74-148 MBq intravenous) and 99mTc-tetrofosmin (740-925 MBq intravenous) studies were performed 20 min after tracer injection and compared. RESULTS: In Group A, no significant difference in the tumor-to-background (T/B) ratio among the 20-, 40- and 120-min postinjection studies was observed. In Group B, the quality of reconstructed images with 99mTc-tetrofosmin, judged visually, was superior to that of 201Tl in 47% of all studies and was comparable in the remaining 53%. A significant relationship between 201Tl and 99mTc-tetrofosmin T/B ratio (r = 0.75, p < 0.01) was found. The T/B ratio of 99mTc-tetrofosmin was significantly higher than that of 201Tl (23.3 +/- 21.5 compared to 6.1 +/- 2.9, p < 0.005). CONCLUSION: Technetium-99m-tetrofosmin is a suitable radiotracer for the imaging of intracranial lesions with SPECT. Moreover, a better definition of tumor margins and a higher contrast between neoplastic and normal brain tissue can be achieved.

An original method for simultaneous display of functional and anatomic images, based on frequency encoding (FE), merges color PET with T1-weighted MR brain images, and grayscale PET with multispectral color MR images. A comparison with two other methods reported in the literature for image fusion (averaging and intensity modulation techniques) was performed. Methods: For FE, the Fourier transform of the merged image was obtained summing the low frequencies of the PET image and the high frequencies of the MR image. For image averaging, the merged image was obtained as a weighted average of the intensities of the two images to be merged. For intensity modulation, the red, green and blue components of the color image were multiplied on a pixel- by-pixel basis by the grayscale image. A comparison of the performances of the three techniques was made by three independent observers assessing the conspicuity of specific MRI and PET information in the merged images. For evaluation purposes, images from seven patients and a computer-simulated MRI/PET phantom were used. Data were compared with a chi-square test applied to ranks. Results: For the depiction of MRI and PET information when merging color PET and T1-weighted MR images, FE was rated superior to intensity modulation and averaging techniques in a significant number of comparisons. For merging grayscale PET with multispectral color MR images, FE and intensity modulation were rated superior to image averaging in terms of both MRI and PET information. Conclusion: The data suggest that improved simultaneous evaluation of MRI and PET information can be achieved with a method based on FE.

Background and purpose: The long-term impact of gadolinium retention in the dentate nuclei of patients undergoing administration of seriate gadolinium-based contrast agents is still widely unexplored. The aim of this study was to evaluate the impact of gadolinium retention on motor and cognitive disability in patients with MS during long-term follow-up. Materials and methods: In this retrospective study, clinical data were obtained from patients with MS followed in a single center from 2013 to 2022 at different time points. These included the Expanded Disability Status Scale score to evaluate motor impairment and the Brief International Cognitive Assessment for MS battery to investigate cognitive performances and their respective changes with time. The association with qualitative and quantitative MR imaging signs of gadolinium retention (namely, the presence of dentate nuclei T1-weighted hyperintensity and changes in longitudinal relaxation R1 maps, respectively) was probed using different General Linear Models and regression analyses. Results: No significant differences in motor or cognitive symptoms emerged between patients showing dentate nuclei hyperintensity and those without visible changes on T1WIs (P = .14 and 0.92, respectively). When we tested possible relationships between quantitative dentate nuclei R1 values and both motor and cognitive symptoms, separately, the regression models including demographic, clinical, and MR imaging features explained 40.5% and 16.5% of the variance, respectively, without any significant effect of dentate nuclei R1 values (P = .21 and 0.30, respectively). Conclusions: Our findings suggest that gadolinium retention in the brains of patients with MS is not associated with long-term motor or cognitive outcomes.

Background/Aim: The differentiation between cerebral metastases (CM) and high-grade gliomas (HGG) can be difficult on magnetic resonance imaging (MRI). The aim of this study was to evaluate the usefulness of searching two MRI signs (signal alteration in the adjacent cortex, SAAC, and peripheral rim sign, PRS), in order to distinguish between these entities. Patients and Methods: A total of 61 patients were retrospectively enrolled (28 HGG, 33 CM). Fluid Attenuated Inversion Recovery (FLAIR) sequences were used to assess SAAC and contrast-enhanced T1-weighted sequences for PRS. Results: A positive SAAC sign was present in 61% of HGG, and 12% of CM. Conversely, in SAAC-negative lesions, PRS was observed in 78% of CM and in 32% of HGG. Their association had a higher frequency in HGG than in the CM group (21 vs. 3%). Conclusion: While SAAC is specific for HGG and PRS, in the absence of SAAC, is relatively specific for CMs, their combined presence is highly suggestive of HGG.

BACKGROUND AND PURPOSE: Conventional MR imaging explains only a fraction of the clinical outcome variance in multiple sclerosis. We aimed to evaluate machine learning models for disability prediction on the basis of radiomic, volumetric, and connectivity features derived from routine brain MR images. MATERIALS AND METHODS: In this retrospective cross-sectional study, 3T brain MR imaging studies of patients with multiple sclerosis, including 3D T1-weighted and T2-weighted FLAIR sequences, were selected from 2 institutions. T1-weighted images were processed to obtain volume, connectivity score (inferred from the T2 lesion location), and texture features for an atlas-based set of GM regions. The site 1 cohort was randomly split into training (n = 400) and test (n = 100) sets, while the site 2 cohort (n = 104) constituted the external test set. After feature selection of clinicodemographic and MR imaging–derived variables, different machine learning algorithms predicting disability as measured with the Expanded Disability Status Scale were trained and cross-validated on the training cohort and evaluated on the test sets. The effect of different algorithms on model performance was tested using the 1-way repeated-measures ANOVA. RESULTS: The selection procedure identified the 9 most informative variables, including age and secondary-progressive course and a subset of radiomic features extracted from the prefrontal cortex, subcortical GM, and cerebellum. The machine learning models predicted disability with high accuracy (r approaching 0.80) and excellent intra- and intersite generalizability (r ≥ 0.73). The machine learning algorithm had no relevant effect on the performance. CONCLUSIONS: The multidimensional analysis of brain MR images, including radiomic features and clinicodemographic data, is highly informative of the clinical status of patients with multiple sclerosis, representing a promising approach to bridge the gap between conventional imaging and disability.

Two women with viral encephalitis of unknown etiology were studied with serial MR studies at 1.5 Tesla using: Spin-Echo (SE) T1-weighted (T1w) sequences before and after i.v. administration of paramagnetic contrast agent, with/without magnetization transfer (MT), Fast SE and Fluid-attenuated Inversion Recovery (FLAIR) T2-weighted sequences, Echo-Planar Single-Shot sequences for the assessment of water diffusivity (Diffusion Weighted, DW, and Apparent Diffusion Coefficient maps, ADC). The DW and T1w sequences with MT after contrast were most useful to detect the initial pathologic alterations, thereby reinforcing the clinical diagnostic hypothesis and prompting appropriate drug treatment, even if the laboratory data were not conclusive for viral etiology. In a later phase, both cases showed MR evidence of lacunar foci in the grey matter, and cortical laminar necrosis, probably indicating a concomitant hypoxic/ischemic mechanism.

A method for postprocessing of segmented routine brain MRI studies providing automated definition of major structures (frontal, parietal, occipital, and temporal lobes; cerebellar hemispheres; and lateral ventricles) according to the Talairach atlas is presented. The method was applied to MRI studies from 25 normal subjects (NV), 14 patients with deficit schizophrenia (DS), and 14 with nondeficit schizophrenia (NDS), to evaluate their gray matter and CSF regional volumes. The two patient groups did not differ in mean age at illness onset, duration of illness, severity of psychotic symptoms, or disorganization; DS had more severe avolition and worse social functioning than NDS. For validation purposes, brain structures were manually outlined on original MR images in 10 studies, thus obtaining reference measures. Manual and automated measures were repeated 1 month apart to measure reproducibilities of both methods. The automated method required less than 1 min/operator per study vs more than 30 min for manual assessment. Mean absolute difference per structure between the two techniques was 4.8 ml. Overall reproducibility did not significantly differ between the two methods. In subjects with schizophrenia, a significant decrease in GM and increase in CSF were found. GM loss was confined to frontal and temporal lobes. Lateral ventricles were significantly larger bilaterally in NDS compared to NV and only on the right in NDS compared to DS. The finding of greater structural brain abnormalities in NDS adds to the evidence that deficit schizophrenia does not represent just the more severe end of the schizophrenia continuum.

Although the diagnosis of epilepsy remains mainly clinical, Magnetic Resonance Imaging (MRI) plays a crucial role in the detection of lesions that can cause epilepsy, with high impact on the diagnostic work-up as well as on therapeutic planning. Morphologic MR imaging is still the main technique for identifying lesions responsible for the epilepsy, providing images with high spatial resolution, excellent soft-tissue contrast, and multiplanar view. Quantitative MR image analysis (segmentation, voxel-based morhometry), based on 3D T1-weighted images, offers an objective means of analyzing MR images thereby improving the capability of detecting subtle lesions, often interpreted as negative by qualitative assessment of the morphologic MR imaging. Diffusion tensor imaging allows the quantification of water molecules diffusion and characterizes the degree and direction of anisotropy. Areas of abnormal diffusion, responsible for epilepsy, may be related to occult dysgenesis, or to acquired damage, resulting in neuronal loss, gliosis, and extracellular space expansion; these changes often result in reduced anisotropy and in an increase in mean diffusivity. Magnetic resonance spectroscopy provides information about the biochemical environment of the brain, thereby helping in lateralizing the epilepsy focus. Functional MR imaging is used for lateralizing language functions, and also for surgical planning predicting functional deficits following epilepsy surgery. The interpretation of MR data should always be done by a neuroradiologist expert in the field of epilepsy imaging, trying to correlate the images with clinical and electrophysiological data.

The Authors report analyses on 83 cases of brain haemorrhage which were conducted over a period of 6 years. On the basis of previous studies made by the same authors, a selection was made from patients whose survival index rating did not exceed 8.1. These patients were treated only with medical and reviving therapies. In this work we attempt to formulate some considerations regarding the prognosis of brain haemorrhage on the basis of clinical and tomodensitometric data.

Introduction: In oncological patients, life quality can be greatly impaired by the presence of painful bone metastases, as standard forms of treatment often achieve inadequate palliation. The aim of our study was to evaluate the clinical efficacy of radiofrequency ablation (RFA) with respect to pain relief in patients with refractory bone metastases or who are ineligible to conventional treatments. Methods: 12 patients with 13 painful osteolytic skeletal metastases, and who were unresponsive to analgesic drug therapy, underwent one (seven lesions) or two (five lesions) RFA sessions under computed tomography (CT) guidance. The RFA procedure was completed in all patients without complications. One patient also received cementoplasty after the RFA procedure. To obtain semiquantitative pain scores, the brief pain inventory (BPI) was administered before treatment and during follow-up. The local effects of RFA were monitored for at least one year in eight of 12 patients with CT and/or magnetic resonance imaging. Results: Immediate pain relief after treatment was experienced by nine of 12 patients, but in two cases, pain recurred within the first week. Long-lasting palliation was obtained in seven of 12 patients. BPI mean scores for worst and average daily pain decreased from 7.7 and 5.0, respectively, at baseline, to 3.1 and 1.8, respectively, at one year. Imaging follow-up showed large areas of necrosis in nine of 12 lesions. Conclusion: In our preliminary experience, RFA showed good and long-lasting efficacy for pain control in bone metastases. A possible role of RFA as a coadjuvant palliative treatment in these cases is suggested.