Magnetic Resonance Imaging

From Embryology
Revision as of 10:39, 1 March 2015 by Z8600021 (talk | contribs)
Embryology - 28 Mar 2024    Facebook link Pinterest link Twitter link  Expand to Translate  
Google Translate - select your language from the list shown below (this will open a new external page)

العربية | català | 中文 | 中國傳統的 | français | Deutsche | עִברִית | हिंदी | bahasa Indonesia | italiano | 日本語 | 한국어 | မြန်မာ | Pilipino | Polskie | português | ਪੰਜਾਬੀ ਦੇ | Română | русский | Español | Swahili | Svensk | ไทย | Türkçe | اردو | ייִדיש | Tiếng Việt    These external translations are automated and may not be accurate. (More? About Translations)

Introduction

Human brain and ventricular development imaged by MRI[1]
Micro-magnetic resonance imaging
Magnetic resonance imaging machine
Open magnetic resonance imaging

Recently there have been several groups preparing developmental embryo atlases of several species, including human[2], 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.


Diffusion Tensor Imaging (DTI) is a newly developed form of magnetic resonance imaging (MRI). Magnetic field variations of the MRI magnet are applied in at least six different directions generating a three dimensional shape of the diffusion pattern. This technique has be used mainly in neural imaging of white matter, due to the orientation of axon bundles and the associated directional water flow. (More? Neural Development Imaging) Computed Tomography is an alternative method of diagnostic imaging using X-rays.


Links: Movies | Neural System - Postnatal | Computed Tomography | Category:Magnetic Resonance Imaging

About MRI

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.

Tesla (symbol T) The SI derived unit of magnetic flux density (or magnetic inductivity) was defined in 1960 and named after Nikola Tesla.

Some Recent Findings

  • Review - Fetal MRI - An approach to practice[3] "MRI has been increasingly used for detailed visualization of the fetus in utero as well as pregnancy structures. Yet, the familiarity of radiologists and clinicians with fetal MRI is still limited. This article provides a practical approach to fetal MR imaging. Fetal MRI is an interactive scanning of the moving fetus owed to the use of fast sequences. Single-shot fast spin-echo (SSFSE) T2-weighted imaging is a standard sequence. T1-weighted sequences are primarily used to demonstrate fat, calcification and hemorrhage. Balanced steady-state free-precession (SSFP), are beneficial in demonstrating fetal structures as the heart and vessels. Diffusion weighted imaging (DWI), MR spectroscopy (MRS), and diffusion tensor imaging (DTI) have potential applications in fetal imaging. Knowing the developing fetal MR anatomy is essential to detect abnormalities. MR evaluation of the developing fetal brain should include recognition of the multilayered-appearance of the cerebral parenchyma, knowledge of the timing of sulci appearance, myelination and changes in ventricular size. With advanced gestation, fetal organs as lungs and kidneys show significant changes in volume and T2-signal. Through a systematic approach, the normal anatomy of the developing fetus is shown to contrast with a wide spectrum of fetal disorders. The abnormalities displayed are graded in severity from simple common lesions to more complex rare cases. Complete fetal MRI is fulfilled by careful evaluation of the placenta, umbilical cord and amniotic cavity."
  • Magnetic resonance diffusion-weighted imaging: reproducibility of regional apparent diffusion coefficients for the normal fetal brain[4] "To evaluate the reproducibility of regional apparent diffusion coefficient (ADC) measurements of the normal fetal brain in the second and third trimesters of pregnancy. Fifty normal singleton fetuses from healthy pregnant women between 19 and 37 weeks' gestation were studied without sedation. ...ADC values either remained constant (BG, FWM, PWM, TWM, OWM, CSO) or decreased (CH, pons, thalamus) with advancing menstrual age."
  • Human birth observed in real-time open magnetic resonance imaging[5] "Knowledge about the mechanism of labor is based on assumptions and radiographic studies performed decades ago. The goal of this study was to describe the relationship between the fetus and the pelvis as the fetus travels through the birth canal, using an open magnetic resonance imaging (MRI) scanner."
  • MRI: is there a role in obstetrics?[6] "Magnetic resonance imaging has a complementary role in obstetrical imaging to ultrasound (US). Although US has advantages as an initial imaging technique, there are significant numbers of patients who cannot be adequately evaluated for a variety of reasons including calvarial calcification, oligoanhydramnios, or simply obesity. MR can provide additional information that cannot be obtained by US and is invaluable in central nervous system anomaly evaluation, airway management, and planning for postnatal intervention. Newer techniques established in the postnatal population such as spectroscopy, diffusion-weighted imaging, and functional imaging have future applications in the fetus."
  • Magnetic resonance imaging and gynecological devices[7] "Though plastic devices do not represent a contraindication to the use of the technique, those including metallic components have been submitted to several tests, after which they were classified as MR Conditional (devices presenting no risks in MR-specific environments) by the Food and Drug Administration. Thus, the use of MRI can be safely advised to women with this type of device as long as the magnetic resonance equipment is ≤3.0 T."
  • World-first at Charité: Birth in "open" MRI 2010.12.07 - Press release | Birth Image | AG OMRT - Radiologie "the birth of a child in an “open” MRI (magnetic resonance imaging) scanner that allows a mother-to-be to fit fully into the machine."
  • Developmental atlas of the early first trimester human embryo.[2]"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.[8] "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

Human Birth

The images below are from a recent study employing new MRI equipment and methodology that allows more free access to the scanned patient compared to the original methodologies. This should allow study of complex physiological processes, such as childbirth, in relative real-time.

Birth- Magnetic Resonance Imaging 01.jpg

2010.12.07 - Press release | Birth Image | AG OMRT - Radiologie "the birth of a child in an “open” MRI (magnetic resonance imaging) scanner that allows a mother-to-be to fit fully into the machine."

Birth- Magnetic Resonance Imaging 02.jpg

This birth is a vertex (head or cephalic) presentation in an occipito-anterior position. Labor stage 2 is shown with the head already within the pelvis birth canal, and lying between the maternal pubic symphysis (anterior) and the sacrum (posterior).


Links: Birth | AG OMRT - Radiologie
Birth MRI icon.jpg
 ‎‎Human Birth MRI
Page | Play

Species Imaging with MRI

Human

  • Whole Embryo[2] "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[1] "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."

Baboon

  • Brain[9] "We devised a protocol to scan pregnant baboons serially at 3 T for up to 3 h per session. Seven baboons were scanned 1-6 times, beginning as early as 56 days post-conceptional age, and as late as 185 days (term approximately 185 days). Successful scanning of the fetal baboon required careful animal preparation and anesthesia, in addition to optimization of the scanning protocol. We successfully acquired maps of relaxation times (T(1) and T(2)) and high-resolution anatomical images of the brains of fetal baboons at multiple time points during the course of gestation."

Monkey Development

Mouse

  • Mouse Mutants[10]"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."
  • A 4D atlas and morphologic database[11] "This work makes magnetic resonance microscopy of the mouse embryo and neonate broadly available with carefully annotated normative data and an extensive environment for collaborations."
Links: Mouse Development | 4D Atlas and Morphologic Database

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."

Chicken Development

Xenopus

  • Early embryo[12]"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
Xenopus-MRI-01-icon.jpg Xenopus-MRI-02-icon.jpg Xenopus-MRI-03-icon.jpg
MRI 01 MRI 02 MRI 03
Links: Movies | Flash Movies | Quicktime Movies

Structure Imaging

Placenta

MRI normal placenta different gestational ages.jpg

MRI normal placenta different gestational ages.[13]

Human placenta vascular 01.jpg
Magnetic resonance angiography (MRA) of human placenta viewed from the fetal side.[14]
Links: Placenta Development

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.[15]

Cochlea MRI 01.jpg Cochlea MRI 02.jpg


Links: Hearing - Inner Ear Development

Adult Skull

Adult Skull MRI Links: Skull Development - MRI
Adult Skull Movie 1 icon.jpg
 ‎‎Viscerocranium
Page | Play
Adult Skull Movie 2 icon.jpg
 ‎‎Temporal Bones
Page | Play
Adult Skull Movie 3 icon.jpg
 ‎‎Occipital - Frontal
Page | Play
Adult Skull Movie 4 icon.jpg
 ‎‎Parietal-Zygomatic
Page | Play


Neural

The following images are from human fixed fetal brains scanned with diffusion tensor magnetic resonance imaging.[1]

Diffusion tensor imaging (DTI) A newly developed form of magnetic resonance imaging (MRI). Magnetic field variations of the MRI magnet are applied in at least six different directions generating a three dimensional shape of the diffusion pattern. This technique can be used in neural imaging of white matter due to the orientation of axon bundles and the associated water flow. (More? Magnetic Resonance Imaging)

Neural DTI Links: Scaled Fissures 13-21 weeks | Fissures 13-21 weeks | Brain Sylvian Fissure | Scaled Brain and Ventricles 13-21 weeks | Scaled Brain, Ventricles and Ganglia 13-21 weeks | Limbic Tract 13-19 weeks | Brain and Ventricles 13-21 weeks | Sylvian Fissure Movie | Neural System Development | Magnetic Resonance Imaging

Brain Tract

Brain Ventricles and Ganglia

Brain Fissures


Links: Neural System Development | Cerebrum Development

Prenatal Diagnosis

Dandy Walker malformation MRI
Dandy Walker malformation MRI GA 26 weeks.[3]

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.[16]"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.[17] "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.[18] "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 | Magnetic Resonance Imaging

References

  1. 1.0 1.1 1.2 <pubmed>20108226</pubmed>
  2. 2.0 2.1 2.2 <pubmed>20503356</pubmed>
  3. 3.0 3.1 <pubmed>25685519</pubmed>| J Adv Res.
  4. <pubmed>22744761</pubmed>
  5. <pubmed>22425409</pubmed>
  6. <pubmed>22343250</pubmed>
  7. <pubmed>22133659</pubmed>
  8. <pubmed>19339620</pubmed>
  9. <pubmed>18155925</pubmed>
  10. <pubmed>20656039</pubmed>
  11. <pubmed>18713865</pubmed>| PMC2527911 | PNAS
  12. <pubmed>16958098</pubmed>
  13. <pubmed>24604945</pubmed>PMC3932583 | Indian J Radiol Imaging.
  14. <pubmed>20226038</pubmed>| BMC Physiol.
  15. <pubmed>19575114</pubmed>| Braz J Otorhinolaryngol.
  16. <pubmed>15234454</pubmed>
  17. <pubmed>16981221</pubmed>
  18. <pubmed>16150769</pubmed>| BMJ


Reviews

<pubmed>19208672</pubmed> <pubmed>19755601</pubmed> <pubmed>19732621</pubmed> <pubmed>18591320</pubmed> <pubmed>17353684</pubmed>

Articles

<pubmed>21308835</pubmed> <pubmed>20656039</pubmed> <pubmed>19076956</pubmed> <pubmed>18709400</pubmed> <pubmed>15615595</pubmed>

Search PubMed

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


External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.


Glossary Links

Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link



Cite this page: Hill, M.A. (2024, March 28) Embryology Magnetic Resonance Imaging. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Magnetic_Resonance_Imaging

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