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?