MRI scarcity in low‐ and middle‐income countries

NMR in Biomedicine · 2023 · 82 citations

• Computer Science
• Political Science
• Business

Since the introduction of MRI as a sustainable diagnostic modality, global accessibility to its services has revealed a wide discrepancy between populations-leaving most of the population in LMICs without access to this important imaging modality. Several factors lead to the scarcity of MRI in LMICs; for example, inadequate infrastructure and the absence of a dedicated workforce are key factors in the scarcity observed. RAD-AID has contributed to the advancement of radiology globally by collaborating with our partners to make radiology more accessible for medically underserved communities. However, progress is slow and further investment is needed to ensure improved global access to MRI.

Normative intracranial EEG maps epileptogenic tissues in focal epilepsy

Brain · 2021 · 78 citations

• Neuroscience
• Psychology
• Medicine

Planning surgery for patients with medically refractory epilepsy often requires recording seizures using intracranial EEG. Quantitative measures derived from interictal intracranial EEG yield potentially appealing biomarkers to guide these surgical procedures; however, their utility is limited by the sparsity of electrode implantation as well as the normal confounds of spatiotemporally varying neural activity and connectivity. We propose that comparing intracranial EEG recordings to a normative atlas of intracranial EEG activity and connectivity can reliably map abnormal regions, identify targets for invasive treatment and increase our understanding of human epilepsy. Merging data from the Penn Epilepsy Center and a public database from the Montreal Neurological Institute, we aggregated interictal intracranial EEG retrospectively across 166 subjects comprising >5000 channels. For each channel, we calculated the normalized spectral power and coherence in each canonical frequency band. We constructed an intracranial EEG atlas by mapping the distribution of each feature across the brain and tested the atlas against data from novel patients by generating a z-score for each channel. We demonstrate that for seizure onset zones within the mesial temporal lobe, measures of connectivity abnormality provide greater distinguishing value than univariate measures of abnormal neural activity. We also find that patients with a longer diagnosis of epilepsy have greater abnormalities in connectivity. By integrating measures of both single-channel activity and inter-regional functional connectivity, we find a better accuracy in predicting the seizure onset zones versus normal brain (area under the curve = 0.77) compared with either group of features alone. We propose that aggregating normative intracranial EEG data across epilepsy centres into a normative atlas provides a rigorous, quantitative method to map epileptic networks and guide invasive therapy. We publicly share our data, infrastructure and methods, and propose an international framework for leveraging big data in surgical planning for refractory epilepsy.

Pearls & Oy-sters: Bilateral globus pallidus lesions in a patient with COVID-19

Neurology · 2020 · 23 citations

• Sociology
• Medicine
• Medical education

Neurologic complications are occurring in coronavirus disease 2019 (COVID-19), and these patients should be monitored for neurologic symptoms.c When evaluating abnormal imaging findings in patients with COVID-19, the presence and specific pattern of deep gray structure involvement can be an important clue to etiology. Oy-sters cBrain imaging should be considered in the context of patients with COVID-19 with neurologic symptoms, even in the absence of focal findings on neurologic examination.c Given the dissociation between degree of hypoxemia and clinical symptoms that can be seen in patients with COVID-19, it is possible that unusual presentations of hypoxicischemic brain injury may emerge.COVID-19, caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was originally described as a viral infection primarily affecting the respiratory tract.Neurologic complications are emerging, and have been reported in 36% of patients hospitalized with COVID-19 and in 46% of those with severe respiratory involvement. 1 The most common neurologic manifestations reported are dizziness, headache, impaired consciousness, dysgeusia, and hyposmia.An increased risk of stroke has also been identified.We report the case of a 52-year-old woman with bilateral globus pallidus lesions in the setting of COVID-19.The patient had a history of hypertension and newly diagnosed, poorly controlled type II diabetes mellitus (hemoglobin A1c of 17.4).She developed bilateral hand paresthesias the week prior to presentation, followed by dyspnea, cough, headache, and confusion.She presented to the emergency department and was afebrile, but tachycardic (115 beats per minute), hypertensive (220/118 mm Hg), and hypoxemic (oxygen saturation 49% on room air).She was alert and conversant, with no focal neurologic deficits.She had refractory hypoxemia despite 20 L/min supplemental oxygen.She was intubated and placed on mechanical ventilation for hypoxemic respiratory failure within 1 hour of presentation.SARS-CoV-2 was detected by rapid, real-time reverse-transcriptase polymerase chain reaction on the Cepheid GeneXpert system from a nasopharyngeal swab sample.Chest CT scan showed extensive bilateral, patchy, peripheral-predominant ground glass opacities with consolidation.Head CT demonstrated symmetric hypoattenuation in the bilateral globi pallidi with surrounding small foci of hyperattenuation (figure, A).Carboxyhemoglobin was not elevated and urine toxicology screen was negative.