Na MRI quantification of sodium content in porcine eyes after immersion in saltwater and freshwater en route to time in water estimation.

BACKGROUND

Differentiation between saltwater and freshwater immersion as well as estimating the corpse's time in water can be challenging. We aimed to establish and examine the feasibility of a novel approach based on sodium magnetic resonance imaging (Na MRI) of the eye to facilitate noninvasive sodium quantification.

METHODS

Enucleated porcine eyes were immersed in NaCl 0.9%, NaCl 3.0%, NaCl 5.85%, distilled water (DW) or lake water (LW) at different time intervals, followed by Na 7-T MRI sodium quantification.

RESULTS

After 6 h of immersion, a significant difference in vitreous body (VB) sodium concentration was found for NaCl 5.85% versus DW or LW (p ≤ 0.019). After 24 and 48 h of immersion, a significant difference in VB sodium concentration was found for NaCl 5.85% versus DW, LW, NaCl 3.0% or NaCl 0.9%, as well as for NaCl 3.0% versus DW, LW or NaCl 0.9% (p ≤ 0.001). After 24 h of immersion, lens sodium concentration showed a significant difference for NaCl 5.85% versus DW, LW, NaCl 3.0% or NaCl 0.9% (p ≤ 0.009); after 48 h of immersion, for NaCl 5.85% versus DW, LW, NaCl 3.0% or NaCl 0.9% (p ≤ 0.001), as well as for NaCl 3.0% versus DW, LW or NaCl 0.9% (p ≤ 0.007). For VB, sodium concentration changes over immersion time, and exponential curves were fitted to the data.

CONCLUSION

Using Na MRI in ex vivo porcine eyes with different immersion times in various saltwater concentrations and freshwater equivalents allowed noninvasive quantification of VB and lens sodium concentrations.

RELEVANCE STATEMENT

Although not a substitute for autopsy, Na MRI assessment of VB and lens sodium concentrations may provide biochemical support in suspected drowning, especially in cases where an internal examination of the body is not authorized or where objections to autopsy are upheld.

KEY POINTS

Postmortem porcine eyes with different immersion times in saltwater and freshwater. Noninvasive quantification of vitreous body and lens sodium concentrations with Na MRI. Exponential time course of vitreous body sodium concentration in saltwater and freshwater.