Portable ultra-low-field MRI in Africa: an access technology in search of an evidence base built without a safety net.

Purpose

Portable ultra-low-field (ULF) magnetic resonance imaging (MRI) is usually judged by how closely it approaches high-field performance. This opinion paper argues that, in many resource-constrained settings, the question is miscast, and sets out how the technology should instead be evaluated.

Method

Drawing on recent systematic reviews and meta-analyses of portable ULF-MRI and on more than fifteen years of neuroradiology practice in Nigeria, the paper examines whether pooled diagnostic-accuracy estimates transfer to settings where the portable scanner may be the only imaging device available.

Results

Diagnostic accuracy and clinical utility are not the same thing. Pooled estimates were derived almost entirely where conventional MRI or computed tomography was immediately available; transferring them assumes comparable case-mix and workflow (spectrum and implementation effects) and, critically, overlooks that without a fallback, the consequences of false-negative, indeterminate and non-diagnostic examinations are far graver. A pooled acute-ischaemic-stroke sensitivity near 73% is a manageable adjunct with backup but means roughly one in four infarcts is missed and left uncorrected without it. Four arguments follow: accuracy estimates may be optimistic and are insufficient for unsupported pathways; interpretation capacity and medicolegal responsibility are decisive but underestimated constraints, alongside cost, power and connectivity; quantitative normative morphometry rests on non-African reference data; and low-field practice in Africa is a decades-old continuity.

Conclusions

Portable ULF-MRI should be evaluated as an access technology on the terms its setting imposes, using a minimum outcome set - including non-diagnostic and indeterminate rates, downstream consequences, and cost per completed diagnostic pathway - not sensitivity alone.