Presented at the Neonatal Society 2008 Spring Meeting.
Thayyil S1, Schievano S1, Robertson NJ2, Jones R1, Sebire NJ3, Taylor AM1.
The Magnetic Resonance Imaging Autopsy Study (MaRIAS) Collaborative Group.
1 Centre for Cardiac Imaging, UCL Institute of Child Health, London, UK
2 EGA UCL Institute for Women’s Health, University College London, London, UK
3 3Histopathology, Great Ormond Street Hospital NHS Trust, London, UK
Magnetic resonance imaging (MRI) allows minimally-invasive autopsy, especially when consent is declined for traditional autopsy. Estimation of individual visceral organ weights is an important component of traditional autopsy. Non-invasive organ weight of all visceral organs by MRI has not been reported before in neonatal and paediatric population.
Objective: To examine whether an automated 3D volume reconstruction model can be used for rapid and accurate non-invasive visceral volume estimation by post-mortem MRI in fetuses, newborns and children.
Methods: Phase 1: In vitro scanning of 36 animal organs (heart, liver, kidney) was performed to check accuracy of volume reconstruction. Real volumes were measured by water displacement method. Phase 2: 60 whole body post mortem MRI (fetuses, newborn and children) were performed at 1.5T (Avanto, Siemens Medical Systems, Erlangen, Germany) and 3D TSE T2 weighted images obtained. Multislice CT scan was also done in selected cases. These data were analysed offline using the image processing software Mimics 9.0 (Materialise Inc, Ann Arbor, MI, USA). Thresholding and region growing were used for 3D volume reconstruction (Figure 1). Specific gravity was assumed to be one for all visceral organs. Study was approved by GOSH-ICH REC and funded by Department of Health, UK.
Results: Phase I: The experiments showed high accuracy of volume reconstruction method for animal organs. Phase II.(see Table 1). Most visceral organs apart from pancreas and thyroid were estimated accurately. Time per organ varied between 2-10 min. Accuracy was lower when fetuses were less than 20 weeks (<300 grams). Organ volumes could not be estimated from CT images, due to poor contrast.
Figure 1: MR data of a neonate, where the purple mask detects the liver in the coronal (1a) plane. (1b, 1c) 3D rendered images of the visceral organs.
Table 1: Comparison between MR calculated weights and actual weights for the different organs for the post-mortem cases.
Conclusion: Accurate estimation of solid visceral organ weights is feasible using the semi-automated 3D volume reconstruction method. This method can be used for rapid, non-invasive organ weight estimation in routine clinical practice, when less invasive autopsy (MR Autopsy) is performed.