Forensic age estimation in the living by 0.31 Tesla low-field MRI of the distal radius

Examination of the radius' distal epiphysis by means of low-field MRI in order to find a reliable method to correctly assess majority in both sexes.

650 volunteers of German nationality, evenly distributed to groups of 25 per sex and years of proven age in the age bracket of 12-24 years, were examined between 2021 and 2023 in a single center, prospective, cross-sectional setting. A 0.31 T dedicated joint scanner was used, acquiring a proton density-weighted (PDw) sequence in Dixon technique (Dixon) in coronal slice orientation yielding a fat-sensitive water-suppressed (fat-only) and a water-sensitive fat-suppressed (water-only) series. A classification was formulated for assessment and tested against the proven age. The relevant statistics were defined, the intra- and interobserver-agreements were determined, and the differences between the sexes were analyzed.

The minimum age for stage 6 of the classification was found to be 18.42 years in male individuals and 17.25 years in female individuals. A Mann-Whitney-U Test implies significant sex-related differences for stage 3 (p < 0.01) and stage 4 (p < 0.01), but not for stage 2 (p < 0.162), stage 5 (p < 0.193) and stage 6 (p < 0.146). The intra- and interobserver-agreement levels were substantial.

When using the presented setting of a low-field 0.31 T dedicated joint scanner, acquiring PDw Dixon fat-only and water-only series of the radius' distal epiphysis and using the presented classification, majority can be determined in male but not in female individuals of our cohort. Therefore, 0.31 T low-field MRI yields similar opportunities as examinations by means of high-field MRI scanners.