Microfocus computed tomography for fetal postmortem imaging: an overview

Abstract

Over the last few years, fetal postmortem microfocus computed tomography (micro-CT) imaging has increased in popularity for both diagnostic and research purposes. Micro-CT imaging could be a substitute for autopsy, particularly in very early gestation fetuses for whom autopsy can be technically challenging and is often unaccepted by parents. This article provides an overview of the latest research in fetal postmortem micro-CT imaging with a focus on diagnostic accuracy, endovascular staining approaches, placental studies and the reversibility of staining. It also discusses new methods that could prove helpful for micro-CT of larger fetuses. While more research is needed, contrast-enhanced micro-CT has the potential to become a suitable alternative to fetal autopsy. Further research using this novel imaging tool could yield wider applications, such as its practise in imaging rare museum specimens.

Less‐invasive autopsy for early pregnancy loss

“…41,57,[83][84][85][88][89][90][91][92][93][94][95] To provide adequate soft tissue contrast, however, an exogenous contrast agent is required, typically potassium tri-iodide (I 2 KI), which stains the soft tissue through cellular diffusion. 46,83,85 Sufficient time must be allowed for complete diffusion, which can take several days or weeks and is dependent on the size of the fetus (Figure 3). 83,85,89,96,97 One downside is that concentrated I 2 KI may result in tissue distortion, although this can be minimised by using a buffered solution.…”

“…83,85,89,96,97 One downside is that concentrated I 2 KI may result in tissue distortion, although this can be minimised by using a buffered solution. 46,71,85,86,98 Endovascular staining using various contrast agents has also been investigated [99][100][101] and may offer opportunities to iodinate larger fetuses in a reduced timeframe in the future. 46 Iodination can cause visible darkening of the fetus, which should be discussed with parents during the consent process and may be initially undesirable but can be partially reversed by sodium thiosulphate solution (Figure 4).…”

“…46,71,85,86,98 Endovascular staining using various contrast agents has also been investigated [99][100][101] and may offer opportunities to iodinate larger fetuses in a reduced timeframe in the future. 46 Iodination can cause visible darkening of the fetus, which should be discussed with parents during the consent process and may be initially undesirable but can be partially reversed by sodium thiosulphate solution (Figure 4). 46,83 This does not necessarily remove the iodine from all body tissues; however, in many cases, it is sufficient to just de-stain the skin for cosmetic purposes prior to returning the body to the parents.…”

“…More advanced post-mortem imaging techniques including High-field (HF) PMMRI and Micro-focus Computed Tomography (micro-CT) imaging 50,71,82,83 have been developed for early fetal loss, primarily to address the combined issues of poor resolution, and low signal and contrast-to-noise ratios. 41,46,49,55,57,61,71,72,82,[84][85][86][87][88]…”

“…To challenge the declining consent rate, less‐invasive autopsy (LIA) techniques, such as laparoscopic examination of the internal organs through smaller incisions or imaging techniques alone, have been developed in recent years, providing a greater and more acceptable choice to parents 10,13,14,27,28,37,39,41–44 . Significant challenges remain in identifying the cause of fetal demise <20 weeks gestational age (GA) or <500 g, as routine imaging techniques (magnetic resonance imaging (MRI), computed tomography (CT), ultrasound, radiographs) cannot provide sufficient resolution, tissue contrast, or soft tissue detail 41,45–49 . It should also be noted that identifying abnormalities in early gestation through CA also remains challenging 47,48,50–57 .…”