A framework for advancing sustainable magnetic resonance imaging access in Africa

Magnetic resonance imaging (MRI) technology has profoundly transformed current healthcare systems globally, owing to advances in hardware and software research innovations. Despite these advances, MRI remains largely inaccessible to clinicians, patients, and researchers in low-resource areas, such as Africa. The rapidly growing burden of noncommunicable diseases in Africa underscores the importance of improving access to MRI equipment as well as training and research opportunities on the continent. The Consortium for Advancement of MRI Education and Research in Africa (CAMERA) is a network of African biomedical imaging experts and global partners, implementing novel strategies to advance MRI access and research in Africa. Upon its inception in 2019, CAMERA sets out to identify challenges to MRI usage and provide a framework for addressing MRI needs in the region. To this end, CAMERA conducted a needs assessment survey (NAS) and a series of symposia at international MRI society meetings over a 2-year period. The 68-question NAS was distributed to MRI users in Africa and was completed by 157 clinicians and scientists from across Sub-Saharan Africa (SSA). On average, the number of MRI scanners per million people remained at less than one, of which 39% were obsolete low-field systems but still in use to meet daily clinical needs. The feasibility of coupling stable energy supplies from various sources has contributed to the growing number of higher-field (1.5 T) MRI scanners in the region. However, these systems are underutilized, with only 8% of facilities reporting clinical scans of 15 or more patients per day, per scanner. The most frequently reported MRI scans were neurological and musculoskeletal. The CAMERA NAS combined with the World Health Organization and International Atomic Energy Agency data provides the most up-to-date data on MRI density in Africa and offers a unique insight into Africa's MRI needs. Reported gaps in training, maintenance, and research capacity indicate ongoing challenges in providing sustainable high-value MRI access in SSA. Findings from the NAS and focused discussions at international MRI society meetings provided the basis for the framework presented here for advancing MRI capacity in SSA. While these findings pertain to SSA, the framework provides a model for advancing imaging needs in other low-resource settings.

Age-related white matter lesions are associated with reduction of the apparent diffusion coefficient in the cerebellum

Cerebellar apparent diffusion coefficient (ADC) was found to be increased after acute cerebral hemispheric stroke. There are no data on cerebellar ADC changes in patients with chronic, age-related white matter lesions (ARWML). We aimed to determine longitudinal ADC variations on cerebral hemispheric and cerebellar white matter regions of patients with ARWML in order to study relations between ADC changes in both regions. ADC was measured serially (1-year interval) on lesioned periventricular frontal white matter, frontal and parietoccipital normal appearing white matter and middle cerebellar peduncles, on 19 aged patients with ARWML, which also underwent gait assessment. We compared regional ADC at 0 and 1 year and calculated variation percentages for each region. Correlation analysis was made between ADC variation in cerebellar regions and in contralateral hemispheric regions and between cerebellar ADC at 1 year and walking speed. After 1 year, ADC was higher on lesioned periventricular frontal white matter and lower on cerebellar regions. ADC variations on these regions were negatively correlated. Cerebellar ADC measured after 1 year was positively correlated with walking speed. This suggests a link between vascular disease progression inside frontal lesions and ADC reduction in contralateral cerebellar peduncles. Chronic ischemia in frontal white matter could have interrupted frontal-cerebellar circuits, producing hypometabolism in cerebellar regions (and worse performance on motor tasks), decreased perfusion and hence ADC reduction.

Assessment of the preferred scout sagittal orientation for temporal lobe imaging with magnetic resonance

Oblique magnetic resonance imaging of the temporal lobe (tilted orientation) requires a stable reference line with minimum variability. In the clinical setting, where several observers carry out examination of the patients, there is a need to assure minimum inter-observer variability, in order to obtain comparable tilted anatomical planes. This is particularly relevant when performing quantitative imaging (qMRI) of the hippocampus, amygdala and para-hippocampal cortices. In this study, eight experienced observers tested the stability of four sagittal reference lines by manually tracing the posterior commissure-obex (PC-OB) line, the line tangential to the anterior surface of the pons at its most convex point and the lines orthogonal to the main axis of both hippocampi, in ten exams of healthy subjects. The stability of the tracing was assessed by comparing the inter-observer variability expressed by the variances of the measurements. The observers' performance was assessed by comparing the precision of the tracing for each line. We tested the results statistically using Bartlett's test (analysis of the variances of the four lines) followed by Fischer-Snedecor (in order to compare the two lines that had the smallest variance). The PC-OB line and the line tangential to the anterior surface of the pons had smaller inter-observer variances than the orthogonal lines (p < 0.01). In addition, the variance of the PC-OB line was smaller than that of the line tangential to the pons (p < 0.01). There were no significant intra-observer differences in the precision of tracing of any of the lines. We show quantitatively that the PC-OB line is the scout reference that yields the smallest inter-observer variance. Thus, this line should be preferred to improve the reproducibility of temporal lobe imaging while performing tilted coronal and axial sequences, to make quantitative assessments of the hippocampus, amygdala and para-hippocampal cortices.