Helium Supply-Chain Vulnerability of MRI Services: A Global Ecological Analysis of Imaging Capacity and Health-System...

The aim of this study was to develop and apply an exploratory country-level Helium-MRI Vulnerability Index (HMVI) to assess structural vulnerability of MRI services to helium supply-chain disruption. This cross-sectional ecological study used publicly available country-level data from the World Health Organization, World Bank, Organisation for Economic Co-operation and Development and US Geological Survey. The global HMVI combined three components: MRI infrastructure dependence, helium supply exposure and health-system resilience. MRI dependence was scored by tertiles of MRI units per million population, helium exposure by national helium production status and resilience by tertiles of current health expenditure per capita. Scores ranged from 0 to 6 and were categorised as low (0-2), moderate (3 and 4) or high (5 and 6) vulnerability. A secondary full HMVI incorporating MRI examinations per 1000 population was calculated for countries with available examination volume data. The global analysis included 140 countries; China and India could not be included because MRI-density data were unavailable. The mean global HMVI was 3.94 ± 0.70, with a median of 4 and an observed range of 2-5. Six countries were classified as low vulnerability, 110 as moderate vulnerability and 24 as high vulnerability. HMVI scores differed significantly across WHO regions (Kruskal-Wallis H = 15.150, p = 0.0097) and World Bank income groups (H = 13.396, p = 0.0039). High-vulnerability countries had lower median health expenditure per capita than non-high-vulnerability countries (240.70 vs. 556.28 USD, p = 0.0051), whereas MRI density did not differ significantly (1.17 vs. 1.51 MRI units per million population, p = 0.3751). The full HMVI subgroup included 24 countries, of which eight were classified as high vulnerability. Sensitivity analysis, excluding countries with 2013 MRI-density data, retained 52 countries and identified five as high vulnerability. The HMVI provides an exploratory framework for characterising structural vulnerability of MRI services to helium supply-chain disruption. Vulnerability was shaped not by MRI density alone, but by the interaction between imaging capacity, helium supply exposure and health-system financial resilience. Updated scanner-level data, including helium consumption and low-helium system adoption, are needed to refine future assessments.