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)
UOG Journal Club: October 2012
Congenital heart
disease (CHD)
Most common
abnormality
≈ 0.8%
One of the leading
causes of infant
mortality
Improved ultrasound
= 1st trimester
diagnosis
High % can be detected by prenatal ultrasound
Hoffman and Kaplan S. J Am Coll Cardiol 2002; Lombardi et al. Ultrasound Obstet Gynecol 2007
Franklin et al. Heart 2002; Thayyil et al. Prenat Diagn 2010
Option of pregnancy termination
Planned birth
Improved neonatal outcome
Impact of early prenatal diagnosis of CHD
Thayyil et al., Prenat Diagn 2010
Accurate postmortem
diagnosis
Proper pregnancy counseling
Termination of pregnancy after early prenatal diagnosis of CHD
Cannie et al., Ultrasound Obstet Gynecol 2012; Brookes et al., Lancet 1996
• 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
Postmortem diagnosis
Votino et al., Ultrasound Obstet Gynecol 2012
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.
Objective
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 autopsyVotino et al., UOG 2012
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
Subjects
Votino et al., Ultrasound Obstet Gynecol 2012
Fetuses were cryopreserved at −20ºC until MRI and stereomicroscopic invasive autopsy.
The MRI scans were performed with:1.5T whole-body magnet: Siemens Avanto3.0T whole-body magnet: Philips Achieva9.4T horizontal bore: Biospec 94/20 USR
Methods
Votino et al., Ultrasound Obstet Gynecol 2012
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
MRI postmortem evaluation
Votino et al., Ultrasound Obstet Gynecol 2012
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
Invasive autopsy
Votino et al., Ultrasound Obstet Gynecol 2012
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%
Results: image quality
Votino et al., Ultrasound Obstet Gynecol 2012
1.5 T 3.0 T 9.4 T Autopsy
Retro-esophageal subclavian artery 0 0 0 1Ventricular septal defect 0 0 1 (20%) 5Atrioventricular septal defect 0 0 1 (50%) 2Transposition of the great arteries 0 0 1 (100%) 1Ventricular hypoplasia 0 0 1 (50%) 2Tetralogy of Fallot 0 0 2 (100%) 2
Results: sensitivity in detecting CHD
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
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 CHDHowever, its limited availability makes it less attractive
for widespread clinical use
Key findings
Votino et al., Ultrasound Obstet Gynecol 2012
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
Limitations
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?