Multimodal MRI Assessment of Thalamic Structural Changes in Earthquake Survivors

Moving from the central role of the thalamus in the integration of inner and external stimuli and in the implementation of a stress-related response, the objective of the present study was to investigate the presence of any MRI structural and volumetric changes of the thalamic structures in earthquake witnesses. Forty-one subjects were included, namely 18 university students belonging to the experimental earthquake-exposed group (8 males and 10 females, mean age 24.5 ± 1.8 years) and a control group of 23 students not living in any earthquake-affected areas at the time of the earthquake (14 males and 9 females, mean age 23.7 ± 2.0 years). Instrumental MRI evaluation was performed using a 3-Tesla scanner, by acquiring a three-dimensional fast spoiled gradient-echo (FSPGR) sequence for volumetric analysis and an EPI (echoplanar imaging) sequence to extract fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values. As compared to the control one, the experimental group showed significantly lower gray matter volume in the mediodorsal nucleus of the left thalamus (p < 0.001). The dominant hemisphere thalamus in the experimental group showed higher mean ADC values and lower mean FA values as compared to the control group.

Single shot echo planar imaging (ssEPI) vs single shot turbo spin echo (ssTSE) DWI of the orbit in patients with ocular melanoma

Objectives: Diffusion weighted imaging (DWI) has become important for orbital imaging. However, the echoplanar imaging (EPI) DWI has inherent obstacles due to susceptibility to magnetic field inhomogeneities. We conducted a comparative study assessing the image quality of orbits in a patient cohort with uveal melanoma (UM). We hypothesized that single shot turbo spin echo (ssTSE) DWI would have better image quality in terms of less distortion and artifacts and yield better tissue evaluation compared to ssEPI-DWI. Methods: ssEPI-DWI and ssTSE-DWI of orbits were obtained from 50 patients with uveal melanoma who were prospectively enrolled in the study. Distortion ratio (DR), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), diffusion signal properties, and apparent diffusion coefficient (ADC) values were collected and compared between ssEPI-DWI and ssTSE-DWI. Two reviewers evaluated and compared the geometric distortion, susceptibility and ghosting artifacts, resolution, demarcation of ocular mass, and overall quality. Results: A higher DR was found in ssEPI-DWI compared to ssTSE-DWI (p < 0.001). SNR and CNR were lower for the temporal lobe cortex (p ≤ 0.004), but higher for melanoma in ssEPI-DWI than ssTSE-DWI (p ≤ 0.037). Geometric distortion and artifacts were more common in ssEPI-DWI (p < 0.001). Resolution (p ≤ 0.013) and overall quality (p < 0.001) were better in ssTSE-DWI. Ocular masses were demarcated better on ssEPI-DWI (p ≤ 0.002). Significant negative correlations between T1 and T2 signal intensities (r = −0.369, p ≤ 0.008) and positive correlations between T2 and both DWI signal intensities (r = 0.686 and p < 0.001 for ssEPI-DWI, r = 0.747 and p < 0.001 for ssTSE-DWI) were revealed. Conclusion: With less geometric distortion and susceptibility artifacts, better resolution, and overall quality, ssTSE-DWI can serve as an alternative to ssEPI-DWI for orbital DWI. Advances in knowledge: ssTSE-DWI can be a better alternative of diffusion imaging of orbits with less susceptibility artifact and geometric distortion compared to ssEPI-DWI.

Neuroplasticity in Corticolimbic Brain Regions in Patients after Anterior Cruciate Ligament Reconstruction

ABSTRACT Context: Fear has been cited as the primary barrier for return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR). Understanding the neural factors contributing to fear after ACLR may help identify interventions for this population. Objective: The objective of this study was to characterize the underlying neural substrate of injury-related fear in patients after ACLR versus healthy matched controls during a picture imagination task (PIT) consisting of sports-specific images and activities of daily living images. Design: Case-Control Study Setting: Research Laboratory Patients or Other Participants: A total of 24 right-hand dominant participants (12 left-sided ACLR and 12 controls) were enrolled. Participants underwent full brain functional magnetic resonance imaging (fMRI). Main Outcome Measure(s): Functional data were acquired with Blood Oxygen Level Dependent (BOLD) echoplanar imaging. Independent t-tests were used to identify significant between group differences in BOLD signal changes during all images of the PIT. Paired t-tests were used to examined differences in BOLD signal change between sports-specific images and activities of daily living (ADLs) in the ACLR group. Results: Increased activation in the inferior parietal lobule (IPL) and the mediodorsal thalamus (MDT) were observed during PIT in the ACLR group. Inability to suppress the default mode network (DMN) in the ACLR group was observed. The ACLR group exhibited increased activation in the cerebellum and inferior occipital regions during the sports-specific task when compared to ADLs, but no other regions of interest demonstrated statistically significant differences. Conclusion: These findings suggest that ACLR patients may be more disposed to processing fear, anxiety, and/or pain for sports-specific activities and activities of daily living. Psychosocial interventions may be warranted after ACLR to reduce injury-related fear and mitigate potentially maladaptive neuroplasticity after ACLR.

0420 Fibre-Specific White Matter Neurodegeneration is Associated with Long Sleep Duration After Stroke

Introduction Long sleep duration in aging populations has recently been proposed as a key modifiable risk factor and sequela of stroke. It is unclear whether the pathogenesis of post-stroke sleep-wake dysfunction is due to focal infarction to regional sleep-wake hubs in the brain, or to accelerated whole-brain neurodegeneration. We utilise a novel technique known as whole-brain fixel-based analyses (FBA) to characterize the first fibre-specific white-matter markers of long sleep duration after stroke. Methods We included 98 radiologically-confirmed ischemic stroke participants (67 male; mean age = 68) and 40 age-matched controls with no history of neurodegenerative disease imaged 3-months post-stroke. Sleep-wake was measured for one week using BodyMedia’s SenseWear armband. Diffusion-weighted MRI (DWI) were acquired using echoplanar imaging and preprocessed using MRtrix3. FBA were employed to identify tracts with altered white-matter fibre-density and fibre-bundle cross-section (FDC) in the long sleep duration (&gt;8 hr, n=20) and normal sleep duration groups (between &gt;6 hr and &lt;8 hr, n=59) compared to controls. Statistical comparisons of FDC between groups were performed at each FDC fixel by a general linear model controlling for age, sex, and intracranial volume. Results Stroke participants with long sleep duration exhibited significant FDC reductions of up to 40% within the cortico-ponto-cerebellar tract when compared to healthy controls (family-wise-error-corrected p=&lt;0.05). Bilateral pontine degeneration was observed at the decussation of the superior cerebellar peduncles. Stroke participants with normal sleep duration exhibited diffuse whole-brain degeneration most apparent along the corpus collosum and cingulum; however, the distribution was less extensive relative to long sleepers (i.e., no cortico-cerebellar projections) and percentage effect reductions did not exceed 20%. Conclusion Long sleep duration after stroke is associated with cortico-ponto-cerebellar degeneration when compared to controls or stroke-participants with normal sleep duration. Excessively long sleep may contribute to post-stroke neurodegeneration beyond the effects of direct infarction and may be a modifiable pharmacological target for abating brain volume loss after stroke. Support This work was supported by the National Health and Medical Research Council project grant (APP1020526), the Brain Foundation, Wicking Trust, Collie-Trust, and Sidney and Fiona Myer Family Foundation. NE was supported by the Australian Research Council DECRA award DE180100893.

Cholesteatoma: multishot echo-planar vs non echo-planar diffusion-weighted MRI for the prediction of middle ear and mastoid cholesteatoma

Objective: We aimed to compare a newer readout-segmented echoplanar imaging (RS-EPI) technique with the established single shot turbo spin echo (SS-TSE) non-EPI diffusion-weighted imaging (DWI) in detecting surgically validated cholesteatoma. Methods: We retrospectively reviewed 358 consecutive MRI studies in 285 patients in which both RS-EPI and non-EPI DWI sequences were performed. Each diffusion sequence was reviewed independently and scored negative, indeterminate or positive for cholesteatoma in isolation and after reviewing the T1W sequence. Average artefacts scores were evaluated and the lesion size measured as a distortion indicator. The imaging scores were correlated with surgical validation, clinical and imaging follow-up. Results: There were 239 middle ear and central mastoid tract and 34 peripheral mastoid lesions. 102 tympanomastoid operations were performed. The positive predictive value ( PPV), post-operative PPV, primary PPV, negative predictive value were 93%, 95%, 87.5%, 70% for RS-EPI and 92.5%, 93.6%, 90%, 79% for non-EPI DWI. There was good agreement between the two techniques (k = 0.75). Non-EPI DWI is less susceptible to skull base artefacts although the mean cholesteatoma measurement difference was only 0.53 mm. Conclusion: RS-EPI has comparable PPV with non-EPI DWI in both primary and post-operative cholesteatoma but slightly lower negative predictive value. When there is a mismatch, non-EPI DWI better predicts the presence of cholesteatoma. There is good agreement between the sequences for cholesteatoma diagnosis. The T1W sequence is very important in downgrading indeterminate DWI signal lesions to a negative score. Advances in knowledge: This is, to our knowledge, the first study to compare a multishot EPI DWI technique with the established non- EPI DWI in cholesteatoma diagnosis.