Magnetic Resonance Imaging

Introduction

Micro-magnetic resonance imaging

Recently there have been several groups preparing developmental embryo atlases of several species, including human, based upon imaging of different age embryos. There have been many studies of adult anatomical structures and also some of the placenta.

Magnetic Resonance Imaging (MRI) began in 1977 and uses magnetism, radio waves, and a computer to produce images either as individual slices or reconstructed to give three dimensional (3D) views of specific anatomical regions or structures.

MRI can be used in fetuses at 18 weeks gestational age or later and has been used mainly in brain and spinal diagnosis, and has also been used to investigate other abnormalities of pregnancy.

Links: Movies | Category:Magnetic Resonance Imaging

About MRI

Magnetic resonance imaging machine

A strong magnetic field (up to 1.5 to 4 Tesla) is generated in the machine through which the body is passed (the centre of the "donut ring" seen in the image). The earth's natural magnetic field is about 0.5 Gauss compared to 15,000 Gauss (1.5 Tesla) in the MRI.

Some Recent Findings

Developmental atlas of the early first trimester human embryo."To obtain data on early human development, we used magnetic resonance (MR) imaging and episcopic fluorescence capture (EFIC) to acquire digital images of human embryos spanning the time of dynamic tissue remodeling and organogenesis (Carnegie stages 13 to 23)." Carnegie_Stages Anatomical characterization of human fetal brain development with diffusion tensor magnetic resonance imaging. "Three-dimensional reconstruction shows that major brain fissures appear while most of the cerebral surface remains smooth until the end of the second trimester. A dominant radial organization was identified at 15 gestational weeks, followed by both laminar and radial architectures in the cerebral wall throughout the remainder of the second trimester. Volumetric measurements of different structures indicate that the volumes of basal ganglia and ganglionic eminence increase along with that of the whole brain, while the ventricle size decreases in the later second trimester." Neural System Development

Species Imaging with MRI

Human

• Embryo"To obtain data on early human development, we used magnetic resonance (MR) imaging and episcopic fluorescence capture (EFIC) to acquire digital images of human embryos spanning the time of dynamic tissue remodeling and organogenesis (Carnegie stages 13 to 23)."

• Brain
  • "Quantitative whole brain 3D validation of tissue labeling performed on a set of 14 fetal MR scans (20.57-22.86 weeks gestational age) demonstrates that this atlas-based EM segmentation approach achieves consistently high DSC performance for the main tissue types in the fetal brain."
  • Anatomical characterization of human fetal brain development with diffusion tensor magnetic resonance imaging.

Mouse

• Mouse Mutants"Using individual 3D embryo MRI histology, we identified new pituitary phenotypes in Hesx1 mutant mice. Subsequently we use advanced computational techniques to produce a whole-body embryo atlas from 6 CD-1 embryos, creating an average image with a greatly enhanced anatomical detail, particularly in CNS structures."

Mouse Development

Chicken

• Eye development PMID19540232 "We subsequently used the images obtained from the MRI data in order to make precise measurements of chick embryo eye surface area, volume and axial length from E4 to E10."

Xenopus

• Early embryo"Here, we report on the use of microscopic magnetic resonance imaging (mMRI) to noninvasively observe mitotic cell division of early blastomeres in the optically opaque Xenopus laevis embryo."

Frog Development

Embryo Imaging

Xenopus Embryo Frog Development

MRI 01	MRI 02	MRI 03

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Structure Imaging

Placenta

Magnetic resonance angiography (MRA) of human placenta viewed from the fetal side.

Adult Inner Ear

The 3D reconstructed technique was used to acquire coronal and axial images of the adult inner ear. The coronal section reconstruction was chosen since it increases visibility of the turns of the cochlea.

Prenatal Diagnosis

MRI can be used in fetuses at 18 weeks gestational age or later and has been used mainly in brain and spinal diagnosis, and has also been used to investigate other abnormalities of pregnancy.

• Absence of harmful effects of magnetic resonance exposure at 1.5 T in utero during the third trimester of pregnancy: a follow-up study."Thirty-five children between 1 and 3 years of age, and nine children between 8 and 9 years of age, that were exposed to MR during the third trimester of pregnancy, were checked for possible adverse effects in a follow-up study. Data on pregnancy and birth, the results of a neurological examination at 3 months, their medical documentary with emphasis on eye and ear functioning, and a questionnaire answered by their mothers were collected and evaluated. In five children abnormal test results were observed, that had no relation to the MR exposure. No harmful effects of prenatal MR exposure in the third trimester of pregnancy were detected in this study."
• Prenatal diagnosis of neurofibromatosis type 1: sonographic and MRI findings. "Prenatal ultrasound and magnetic resonance imaging (MRI) demonstrated a large oropharyngeal tumor, and cardiac and cranial abnormalities consistent with neurofibromatosis type 1 (NF1) in a third-trimester fetus, which were confirmed on postmortem examination. Sonographic features of NF1 are generally nonspecific; MR examination provided significant additional information, facilitating prenatal diagnosis."
• In utero magnetic resonance imaging for brain and spinal abnormalities in fetuses. "In the past eight years magnetic resonance imaging has been used to detect fetal abnormalities in utero at many centres around the world."

Links: Prenatal Diagnosis

References

Reviews

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Search PubMed

Search Pubmed: Embryo Magnetic Resonance Imaging | Magnetic Resonance Imaging |

External Links

• Brookhaven National Laboratory New MicroMRI Facility Expands Lab's Brain-Imaging Capabilities

Glossary Links

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Cite this page: Hill, M.A. (2024, May 3) Embryology Magnetic Resonance Imaging. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Magnetic_Resonance_Imaging

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G