The use of whole body diffusion-weighted post-mortem magnetic resonance imaging in timing of perinatal deaths.

Objectives: Diffusion-weighted MRI provides information regarding body water movement following death, which may be an imaging marker of post-mortem interval (time since death; PMI) or maceration (degree of tissue degradation during intra-uterine retention) in perinatal deaths. Our aim was to evaluate the relationship between maceration, PMI and body organ apparent diffusion coefficient (ADC) values in a cohort of subjects across a wide gestational range.

Materials: Whole body post-mortem MRI with diffusion-weighted imaging (DWI) sequences were performed at 1.5 T, with b values of 0, 500 and 1000 mm/s. Mean ADC values were calculated from regions of interest (ROIs) placed in the lungs, myocardium, spleen, renal cortex, liver and psoas muscle by two independent readers. Multivariable regression analysis was performed against PMI, gestational age, post-mortem weight, maceration score and gender.

Results: Eighty perinatal deaths were imaged with mean gestational age of 32 weeks (18-41 weeks), of which 49 (61.3%) were male. The mean PMI was 8 days (1-18 days). Maceration scores were statistically significant predictive factors for ADC values in all included body organs except the lungs, but PMI was not a predictor for ADC values in any body organ. In the absence of maceration (n = 14), PMI was not statistically associated with ADC values in any of the body areas. The ratio of agreement in the majority of body areas was close to 1 (range between 0.95 and 1.10).

Conclusion: Maceration, not PMI, is significantly associated with ADC values in perinatal deaths. Further research is needed to understand organ-specific changes in the post-mortem period.