Pearls & Oy-sters: Bibrachial Amyotrophy From a Dural Tear.

Bibrachial amyotrophy signifies a clinical phenotype characterized by weakness in both upper extremities with preserved strength in the face, neck, and lower extremities. The underlying causes of bibrachial amyotrophy are broad. We report a patient exhibiting bibrachial amyotrophy who initially received a diagnosis of amyotrophic lateral sclerosis (ALS); however, his clinical course and NCS/EMG were atypical for ALS. Further evaluation demonstrated dural tears with CSF leak, resulting in a compressive extradural fluid collection, ventral myelopathy, and intracranial hypotension. Dural tear and ALS have overlapping features, including the manifestation of the bibrachial amyotrophy phenotype and the presence of T2 hyperintensities in the anterior horn cells, recognized by an "owl's eye" appearance on spine MRI. Clinical and radiologic vigilance is required to identify rare cases of dural tear causing ventral myelopathy that manifest as bibrachial amyotrophy.

Association of Baseline Cerebrovascular Reactivity and Longitudinal Development of Enlarged Perivascular Spaces in the Basal Ganglia.

BACKGROUND: Increasing evidence suggests that enlarged perivascular spaces (ePVS) are associated with cognitive dysfunction in aging. However, the pathogenesis of ePVS remains unknown. Here, we tested the possibility that baseline cerebrovascular dysfunction, as measured by a magnetic resonance imaging measure of cerebrovascular reactivity, contributes to the later development of ePVS. METHODS: Fifty cognitively unimpaired, older adults (31 women; age range, 60-84 years) underwent magnetic resonance imaging scanning at baseline and follow-up separated by ≈2.5 years. ePVS were counted in the basal ganglia, centrum semiovale, midbrain, and hippocampus. Cerebrovascular reactivity, an index of the vasodilatory capacity of cerebral small vessels, was assessed using carbon dioxide inhalation while acquiring blood oxygen level-dependent magnetic resonance images. RESULTS: Low baseline cerebrovascular reactivity values in the basal ganglia were associated with increased follow-up ePVS counts in the basal ganglia after controlling for age, sex, and baseline ePVS values (estimate [SE]=-3.18 [0.96]; P=0.002; [95% CI, -5.11 to -1.24]). This effect remained significant after accounting for self-reported risk factors of cerebral small vessel disease (estimate [SE]=-3.10 [1.00]; P=0.003; [CI, -5.11 to -1.09]) and neuroimaging markers of cerebral small vessel disease (estimate [SE]=-2.72 [0.99]; P=0.009; [CI, -4.71 to -0.73]). CONCLUSIONS: Our results demonstrate that low baseline cerebrovascular reactivity is a risk factor for later development of ePVS.

Equipment Setup and Artifact Removal for Simultaneous Electroencephalogram and Functional Magnetic Resonance Imaging for Clinical Review in Epilepsy.

Simultaneous electroencephalogram and functional magnetic resonance imaging (EEG-fMRI) is a unique combined technique that provides synergy in the understanding and localization of seizure onset in epilepsy. However, reported experimental protocols for EEG-fMRI recordings fail to address details about conducting such procedures on epilepsy patients. In addition, these protocols are limited solely to research settings. To fill the gap between patient monitoring in an epilepsy monitoring unit (EMU) and conducting research with an epilepsy patient, we introduce a unique EEG-fMRI recording protocol of epilepsy during the interictal period. The use of an MR conditional electrode set, which can also be used in the EMU for a simultaneous scalp EEG and video recording, allows an easy transition of EEG recordings from the EMU to the scanning room for concurrent EEG-fMRI recordings. Details on the recording procedures using this specific MR conditional electrode set are provided. In addition, the study explains step-by-step EEG processing procedures to remove the imaging artifacts, which can then be used for clinical review. This experimental protocol promotes an amendment to the conventional EEG-fMRI recording for enhanced applicability in both clinical (i.e., EMU) and research settings. Furthermore, this protocol provides the potential to expand this modality to postictal EEG-fMRI recordings in the clinical setting.

Enlarged Perivascular Spaces Are Negatively Associated With Montreal Cognitive Assessment Scores in Older Adults.

Emerging evidence suggests that enlarged perivascular spaces (ePVS) may be a clinically significant neuroimaging marker of global cognitive function related to cerebral small vessel disease (cSVD). We tested this possibility by assessing the relationship between ePVS and both a standardized measure of global cognitive function, the Montreal Cognitive Assessment (MoCA), and an established marker of cSVD, white matter hyperintensity volume (WMH) volume. One hundred and eleven community-dwelling older adults (56-86) underwent neuroimaging and MoCA testing. Quantification of region-specific ePVS burden was performed using a previously validated visual rating method and WMH volumes were computed using the standard ADNI pipeline. Separate linear regression models were run with ePVS as a predictor of MoCA scores and whole brain WMH volume. Results indicated a negative association between MoCA scores and both total ePVS counts (P ≤ 0.001) and centrum semiovale ePVS counts (P ≤ 0.001), after controlling for other relevant cSVD variables. Further, WMH volumes were positively associated with total ePVS (P = 0.010), basal ganglia ePVS (P ≤ 0.001), and centrum semiovale ePVS (P = 0.027). Our results suggest that ePVS burden, particularly in the centrum semiovale, may be a clinically significant neuroimaging marker of global cognitive dysfunction related to cSVD.

Deep learning versus iterative reconstruction on image quality and dose reduction in abdominal CT: a live animal study.

Objective.While simulated low-dose CT images and phantom studies cannot fully approximate subjective and objective effects of deep learning (DL) denoising on image quality, live animal models may afford this assessment. This study is to investigate the potential of DL in CT dose reduction on image quality compared to iterative reconstruction (IR).Approach.The upper abdomen of a live 4 year old sheep was scanned on a CT scanner at different exposure levels. Images were reconstructed using FBP and ADMIRE with 5 strengths. A modularized DL network with 5 modules was used for image reconstruction via progressive denoising. Radiomic features were extracted from a region over the liver. Concordance correlation coefficient (CCC) was applied to quantify agreement between any two sets of radiomic features. Coefficient of variation was calculated to measure variation in a radiomic feature series. Structural similarity index (SSIM) was used to measure the similarity between any two images. Diagnostic quality, low-contrast detectability, and image texture were qualitatively evaluated by two radiologists. Pearson correlation coefficient was computed across all dose-reconstruction/denoising combinations.Results.A total of 66 image sets, with 405 radiomic features extracted from each, are analyzed. IR and DL can improve diagnostic quality and low-contrast detectability and similarly modulate image texture features. In terms of SSIM, DL has higher potential in preserving image structure. There is strong correlation between SSIM and radiologists' evaluations for diagnostic quality (0.559) and low-contrast detectability (0.635) but moderate correlation for texture (0.313). There is moderate correlation between CCC of radiomic features and radiologists' evaluation for diagnostic quality (0.397), low-contrast detectability (0.417), and texture (0.326), implying that improvement of image features may not relate to improvement of diagnostic quality.Conclusion.DL shows potential to further reduce radiation dose while preserving structural similarity, while IR is favored by radiologists and more predictably alters radiomic features.

Iterative Reconstruction in Dose Reduction of A Head CT Examination and Corresponding Acquisition Parameter Selection.

PURPOSE: To investigate the potential of iterative reconstruction in radiation dose reduction during head computed tomography (CT) examinations and to evaluate the relationship between the parameters milliampere second (mAs), kilovoltage (kV), and iterative reconstruction strength using a live ovine (sheep) model. METHODS: A sheep was scanned on a SOMATOM Force (Siemens Healthineers) CT scanner at 12 mAs and 3 kV. Images were reconstructed with filtered back projection (FBP) and the Advanced Modeled Iterative Reconstruction (ADMIRE; Siemens Healthineers) strengths 1 to 5. Images with 216 combinations of varying doses, kVs, and reconstructions were rated by 2 neuroradiologists for low-contrast detectability (ie, gray-white matter differentiation) and image texture. RESULTS: Using only gray-white matter differentiation, maximum dose reduction was 75% at 100 kV with ADMIRE-3, and using only image texture, maximum dose reduction was 75% at 120 kV (and 140 kV) with ADMIRE-5. When these 2 metrics were combined, maximum dose reduction was 50% at 120 kV with ADMIRE-3. Other kV levels and higher iterative reconstruction strengths did not offer superior results. DISCUSSION: Although artificial intelligence algorithms are certainly gaining momentum, iterative reconstruction technology likely will remain more accessible to most hospitals and imaging centers. Dose reduction with preservation of image quality (ie, gray-white differentiation and image texture) can be achieved when complemented by appropriate iterative reconstruction strength. However, the effect of iterative reconstruction strength on gray-white differentiation and image texture does not necessarily converge on the same pattern. CONCLUSION: Maximum dose reduction was 50% at 120 kV with ADMIRE-3, which confirms the potential for dose reduction with appropriately chosen iterative reconstruction strength and reveals a preference for 120 kV, as well as a limit to dose reduction by further increasing iterative reconstruction strength. A better understanding of dose-voltage-reconstruction relationships in iterative reconstruction might allow for greater dose reductions than current practices allow.

Cortical iron disrupts functional connectivity networks supporting working memory performance in older adults.

Excessive brain iron negatively affects working memory and related processes but the impact of cortical iron on task-relevant, cortical brain networks is unknown. We hypothesized that high cortical iron concentration may disrupt functional circuitry within cortical networks supporting working memory performance. Fifty-five healthy older adults completed an N-Back working memory paradigm while functional magnetic resonance imaging (fMRI) was performed. Participants also underwent quantitative susceptibility mapping (QSM) imaging for assessment of non-heme brain iron concentration. Additionally, pseudo continuous arterial spin labeling scans were obtained to control for potential contributions of cerebral blood volume and structural brain images were used to control for contributions of brain volume. Task performance was positively correlated with strength of task-based functional connectivity (tFC) between brain regions of the frontoparietal working memory network. However, higher cortical iron concentration was associated with lower tFC within this frontoparietal network and with poorer working memory performance after controlling for both cerebral blood flow and brain volume. Our results suggest that high cortical iron concentration disrupts communication within frontoparietal networks supporting working memory and is associated with reduced working memory performance in older adults.

Reversible manifestations of extraparenchymal neurocysticercosis.

Movement disorders are uncommon manifestations of neurocysticercosis. When present, most are secondary to parenchymal lesions in the basal ganglia. Rarely, movement disorders can occur in racemose/extraparenchymal neurocysticercosis, an aggressive variant frequently associated with cerebrospinal fluid outflow obstruction and hydrocephalus. Appropriate treatment can reverse neurological manifestations.

Surfer's myelopathy without surfing: a report of two pediatric patients.

INTRODUCTION: Surfer's myelopathy (SM) is a rare disorder described in subjects presenting with acute paraparesis while learning how to surf. It is thought to be secondary to spinal ischemia triggered by hyperextension. Spinal magnetic resonance imaging (MRI) shows changes consistent with spinal cord ischemia on T2-weighted and diffusion-weighted imaging (DWI). CASE PRESENTATION: We report two patients who presented with acute onset paraplegia shortly after spinal hyperextension. They had no physical or radiological evidence of soft tissue injury. Their clinical and imaging findings closely resemble those described in SM. DISCUSSION: We propose the use of the term 'acute hyperextension myelopathy' to categorize patients with spinal cord infarction secondary to hyperextension. DWI sequencing on MRI should be considered to evaluate for early signs of spinal cord ischemia in these patients. Use of a broader term for diagnostic classification can help include patients with spinal cord infarction due to a common mechanism.

Imaging of Functional and Dysfunctional Episodic Memory.

A foundational framework for understanding functional and dysfunctional imaging of episodic memory emerges from the last 3 decades of human and animal research. This comprehensive review is presented from the vantage point of the fornix, a white matter bridge that occupies a central position in this functional network. Salient insights are identified, spanning topics such as hippocampal efferent and afferent networks, input and processing streams, hemispheric specialization, dysfunctional effects of pathologic and surgical injury, optimization of functional magnetic resonance imaging design and neuropsychological tests, and rehabilitation strategies. Far-reaching implications are considered for radiologists, whose clinical effect stretches beyond imaging and interfaces with neurosurgeons, neuropsychologists, and other neurospecialists.