Affiliations
1 Department of Biomedical Imaging and Image-Guided Therapy, Medical
University of Vienna, Austria
2 Clinical Institute for Pathology, Medical University of Vienna,
Austria
3 Division of Neuropathology and Neurochemistry, Department of
Neurology, Medical University of Vienna, Austria
MR imaging is of ever-growing interest in the obstetric community and
post-mortem confirmation is crucial in the improvement of this
technique. Griffiths et al. assessed the concordance between fetal MRI
and brain autopsy in fetuses of the MERIDIAN cohort that ended in
termination of pregnancy (BJOG 2020 xxxx). Sixty-two fetuses were
evaluated with a concordance of 84% (52/62), which is in accordance
with similar studies (Izzo et al. Eur Radiol 2019;29(6):2740-2750). Of
ten cases with a disagreement, eight were related to cerebellar
malformations or callosal abnormalities.
We would like to stress the importance of post-mortem MRI (PMMR), which
could further elucidate disagreements between autopsy and in-utero MRI.
PMMR, like any other technique, has limitations, such as limited
interpretability due to maceration, and the possibility of
non-diagnostic images. Nevertheless, PMMR provides relevant additional
diagnostic information, especially in cases where autolysis prevents
detailed autopsy (Arthurs et al. Clin Radiol 2015;70(8):872-80). By
identifying poor tissue preservation, PMMR may also be efficiently
integrated in the post-mortem workup strategy in fetal brain
abnormalities. Especially in the setting of posterior fossa
malformations, PMMR could be a valuable adjunct.
In the past decade, there has been a strong scientific interest in
post-mortem imaging, driven by centers in Great Britain, which have
developed a high level of sophistication in this field (Ashwin et al.
Prenat Diagn 2017;37(6):566-574). Although, centers that perform fetal
MRI according to guidelines should also have the knowledge and technical
capabilities to perform PMMR, this technique is generally still
underused. This stands in contrast to the high parental acceptance of
PMMR over conventional autopsy (Cannie et al. Ultrasound Obstet Gynecol
2012;39(6):659-65). Despite prospective design and scientific
third-party funding support of the current study, surprisingly 55% of
abortions went without post-mortem brain examination, by neither autopsy
nor PMMR. This may indicate limited availability of post-mortem
diagnostics even in the setting of a well-planned prospective study.
Further, there is the possibility of a selection bias of cases
undergoing autopsy, which needs to be addressed and openly discussed to
adequately bill this important source of quality assurance.
Comparing in-vivo imaging to autopsy is challenging for several reasons.
As both are influenced by data quality, data homogenization by
exclusively comparing excellent MR image quality to autopsies with
excellent tissue quality without autolytic changes may help to optimally
identify the complementary value of both modalities. Further, an exact
definition of the procedure of fetal brain autopsy is crucial to
understand to which standard imaging was compared. Fetal brain autopsy
can be performed macro- and microscopically (±immunohistochemistry),
substantially impacting the level of detail of autopsy findings. Data
heterogeneity is also influenced by the variable expertise of
pathologists, with only very few being experienced in fetal
neuropathology. As we were not able to extract these important aspects
from the current paper and they were not explicitly described in the
MERIDIAN study protocol (Griffiths et al. The Lancet
2017;389(10068):538-546), we had difficulties in acknowledging and
understanding the value of the presented data.
Finally, we hope for initiatives promoting the use of PMMR and further
supporting training in fetal neuropathology as important quality
control. Improving the accuracy of prenatal neuroimaging will optimize
our ethically sensitive decision making in this field. Post-mortem
validation by a well-defined imaging and autopsy workup will require
support by funding agencies in order to maintain and develop a high
standard of quality.
Disclosure of interest: The authors have nothing to declare.
Completed disclosure of interest forms are available to view online as
supporting information.