# 23Na MRI quantification of sodium content in porcine eyes after immersion in saltwater and freshwater en route to time in water estimation

## TL;DR

This study explores using 23Na MRI to measure sodium in porcine eyes after immersion in saltwater or freshwater, aiming to estimate time in water and differentiate immersion types.

## Contribution

The novel use of 23Na MRI for noninvasive sodium quantification in postmortem eyes to aid in forensic time-in-water estimation.

## Key findings

- 23Na MRI detected significant differences in vitreous body sodium concentration after 6 hours of immersion in saltwater versus freshwater.
- Exponential curves modeled sodium concentration changes over immersion time in different saltwater and freshwater conditions.
- Lens sodium concentrations also showed significant differences after 24 and 48 hours of immersion in various saltwater and freshwater solutions.

## Abstract

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 (23Na MRI) of the eye to facilitate noninvasive sodium quantification.

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 23Na 7-T MRI sodium quantification.

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.

Using 23Na 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.

Although not a substitute for autopsy, 23Na 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.

Postmortem porcine eyes with different immersion times in saltwater and freshwater.Noninvasive quantification of vitreous body and lens sodium concentrations with 23Na MRI.Exponential time course of vitreous body sodium concentration in saltwater and freshwater.

Postmortem porcine eyes with different immersion times in saltwater and freshwater.

Noninvasive quantification of vitreous body and lens sodium concentrations with 23Na MRI.

Exponential time course of vitreous body sodium concentration in saltwater and freshwater.