fNIRS in global child health research: insights from failure mode and effects analysis on a longitudinal project in Bangladesh.

Significance: Neuroimaging research on child development in low- and middle-income countries (LMICs) remains limited, in part due to substantial implementation challenges. Although functional near-infrared spectroscopy (fNIRS) is a promising tool in these contexts, its use is constrained by barriers that are not yet systematically characterized. Aim: We systematically evaluate the challenges encountered during a 3-year longitudinal fNIRS project with children in Dhaka, Bangladesh. We aim to identify the major challenges affecting data quality and collection, compare our findings with similar studies in other LMICs, and gather practical guidance for fNIRS implementation in LMICs. Approach: We applied failure mode and effects analysis to systematically identify the major challenges in the project. We also polled researchers with experience in similar fNIRS studies in other LMICs and compiled mitigation strategies. Results: High-risk challenges were primarily related to fNIRS headcap fit, onsite staff procedures, and environmentally related fNIRS equipment functionality. Most of these challenges were also reported by other polled sites. Effective mitigation strategies have been compiled based on experience in Dhaka and insights from multiple LMICs. Conclusions: We provide valuable insights into the challenges of implementing fNIRS in LMICs by identifying high-priority challenges and effective mitigation strategies, ultimately informing more equitable and reliable fNIRS research in global child health.