Body weight-based iodinated contrast immersion timing for human fetal postmortem microfocus computed tomography

Abstract

Objectives: The aim of this study was to evaluate the length of time required to achieve full iodination using potassium tri-iodide as a contrast agent, prior to human fetal postmortem microfocus computed tomography (micro-CT) imaging.

Methods: Prospective assessment of optimal contrast iodination was conducted across 157 human fetuses (postmortem weight range 2-298 g; gestational age range 12-37 weeks), following micro-CT imaging. Simple linear regression was conducted to analyse which fetal demographic factors could produce the most accurate estimate for optimal iodination time.

Results: Postmortem body weight (r² = 0.6435) was better correlated with iodination time than gestational age (r² = 0.1384), producing a line of best fit, y = [0.0304 × body weight (g)] - 2.2103. This can be simplified for clinical use whereby immersion time (days) = [0.03 × body weight (g)] - 2.2. Using this formula, for example, a 100-g fetus would take 5.2 days to reach optimal contrast enhancement.

Conclusions: The simplified equation can now be used to provide estimation times for fetal contrast preparation time prior to micro-CT imaging and can be used to manage service throughput and parental expectation for return of their fetus.

Advances in knowledge: A simple equation from empirical data can now be used to estimate preparation time for human fetal postmortem micro-CT imaging.

Keywords: fetal; immersion time; micro-CT; potassium tri-iodide.

Figure 1.

Axial micro-CT example images of a 265-g fetus at 20 weeks of gestation demonstrate incomplete iodination (A and B) after 7 days, but complete iodination (C and D) in the head and chest after 10 days.

Figure 2.

Simple linear regression analysis demonstrates that gestational age was a poor predictor (r² = 0.14), and body weight was a good predictor of immersion time (r² = 0.64).