Paediatric AILD cohort with AIH and ASC underwent LiverMultiScan, MRCP+, biopsy, and blood-based liver function tests. Quantitative MRCP+ biliary metrics discriminated AIH from ASC, supporting noninvasive subtype stratification. Although cT1 did not differ between subtypes, LiverMultiScan provided parenchymal characterization and longitudinal monitoring, complementing MRCP+ for comprehensive assessment.