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UOG Journal Club: October 2012
Postmortem examination of human fetal hearts at or
below 20 weeks’ gestation: a comparison of high-field
MRI at 9.4 T with lower-field MRI magnets and
stereomicroscopic autopsy
C. Votino, J. Jani, M. Verhoye, M. Verhoye, B. Bessieres, Y. Fierens, V. Segers,
A. Vorsselmans, X. Kang, T. Cos, W. Foulon, J. de Mey and M. Cannie.
Volume 40, Issue 4, Date: October 2012, pages 437–444
Journal Club slides prepared by Dr Wellington P Martins
(UOG Editor for Trainees)
Most
common
abnormality
≈ 0.8%
One of the
leading
causes of
infant
mortality
Congenital
heart
disease
(CHD)
High % can
be detected
by prenatal
ultrasound
Improved
ultrasound
= 1st
trimester
diagnosis
Hoffman and Kaplan S. J Am Coll Cardiol 2002; Lombardi et al. Ultrasound Obstet Gynecol 2007
Impact of early prenatal diagnosis of CHD
Option of pregnancy
termination
Planned birth
Improved neonatal outcome
Franklin et al. Heart 2002; Thayyil et al. Prenat Diagn 2010
Termination of pregnancy after early
prenatal diagnosis of CHD
Accurate
postmortem
diagnosis
Proper
pregnancy
counseling
Thayyil et al., Prenat Diagn 2010
Postmortem diagnosis
• Conventional/invasive autopsy
– Gold standard for postmortem diagnosis
– Parents acceptance is poor
• Whole body MRI as an alternative
– 1.5 T MRI introduced a decade ago
• Limited use for CHD in small fetuses
• Relatively low resolution
– 9.4 T MRI has improved resolution
• Diagnostic accuracy almost equivalent to invasive autopsy
Cannie et al., Ultrasound Obstet Gynecol 2012; Brookes et al., Lancet 1996
Postmortem examination of human fetal hearts at or below 20 weeks’
gestation: a comparison of high-field MRI at 9.4 T with lower-field MRI
magnets and stereomicroscopic autopsy
Votino et al., UOG 2012
Objective
To compare the diagnostic usefulness of high-field (9.4 T)
with lower-field (1.5 T and 3.0 T) MRI against the gold
standard of stereomicroscopic autopsy for the postmortem
examination of the fetal heart in fetuses ≤ 20 weeks’
gestation.
Votino et al., Ultrasound Obstet Gynecol 2012
Subjects
Fetuses ≤ 20 weeks, with any abnormality on prenatal
ultrasound; parents opted for termination of pregnancy
(TOP) (n=22)
Fetuses ≤ 20 weeks, spontaneous miscarriage, heart beat
detected when admitted to hospital (n=2).
Total = 24 fetuses (14 normal and 10 with CHD)
•
•
•
•
abnormal four-chamber view (n=9)
abnormal outflow tracts (n=4)
abnormal aortic arch (n=3)
abnormal systemic venous return (n=2)
Votino et al., Ultrasound Obstet Gynecol 2012
Methods
Fetuses were cryopreserved at −20ºC until MRI and
stereomicroscopic invasive autopsy.
The MRI scans were performed with:
1.5T whole-body magnet: Siemens Avanto
3.0T whole-body magnet: Philips Achieva
9.4T horizontal bore: Biospec 94/20 USR
Votino et al., Ultrasound Obstet Gynecol 2012
MRI postmortem evaluation
MRI performed by three different operators blinded
to the prenatal scan findings
Single radiologist evaluated the MRIs
•
•
•
•
10 years’ experience in fetal and postmortem MRI
Offline analysis of acquired volumes
Following order: 1.5 T, 3.0 T, and 9.4 T
1-month delay between readings
Votino et al., Ultrasound Obstet Gynecol 2012
Invasive autopsy
Invasive autopsies were conducted and/or supervised by a
single pathologist with 20 years’ experience in fetal
pathology and 12 years in cardiac fetal pathology
Unaware of results of prenatal scan and MRI findings
Votino et al., Ultrasound Obstet Gynecol 2012
Results: image quality
1.5 T
3.0 T
9.4 T
Ability to visualize different fetal heart structures (n=24)
Situs
4 chamber Outflow tracts Aortic arch Systemic veins
1.5 T
62.5%
25.0%
0.0%
0.0%
0.0%
3.0 T
70.8%
45.8%
4.2%
0.0%
0.0%
9.4 T
100.0%
100.0%
100.0%
83.3%
79.2%
Votino et al., Ultrasound Obstet Gynecol 2012
Results: sensitivity in detecting CHD
Retro-esophageal subclavian artery
Ventricular septal defect
Atrioventricular septal defect
Transposition of the great arteries
Ventricular hypoplasia
Tetralogy of Fallot
1.5 T 3.0 T
0
0
0
0
0
0
0
0
0
0
0
0
9.4 T
Autopsy
0
1
1 (20%)
5
1 (50%)
2
1 (100%)
1
1 (50%)
2
2 (100%)
2
9.4 T MRI examination also diagnosed two cases of
ventricular septal defect (VSD) not confirmed by invasive
autopsy
Votino et al., Ultrasound Obstet Gynecol 2012
Key findings
For the postmortem examination of the fetal heart before 20
weeks’ gestation:
1.5 T or 3.0 T MRI seem to be limited
9.4 T MRI seems to be able to detect major CHD
However, its limited availability makes it less attractive for
widespread clinical use
Votino et al., Ultrasound Obstet Gynecol 2012
Limitations
Small sample size
• Only a small variety of CHD was examined
Some fetuses were frozen/thawed before MRI
• This can possibly interfere with image quality
• Could compromise integrity of tissue structure
• Improved image quality for the fetal heart
Only non-macerated fetuses were examined
• Limited the generalizability of the findings
• Ideal conditions will not always be possible
Votino et al., Ultrasound Obstet Gynecol 2012
Discussion points
• Is first-trimester ultrasound diagnosis of fetal congenital heart disease
accurate enough to help parents decide on termination of pregnancy?
• Is the postmortem diagnostic confirmation necessary for future
pregnancy counselling and management?
• Are the current imaging methods accurate/reliable for postmortem
investigation of fetal congenital heart diseases?
• Is the accuracy of congenital heart disease by postmortem imaging
methods better than that obtained by prenatal ultrasound?
• Is the conventional postmortem examination currently a well accepted
procedure by parents?
• Is postmortem examination limited to imaging methods only more or
less likely to be accepted by parents?
Votino et al., Ultrasound Obstet Gynecol 2012