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MR imaging of anisotropically restricted diffusion in the brain of neonates and infants
M A Rutherford1, F M Cowan, A Y Manzur
1Department of Pediatrics and Neonatal Medicine, Hammersmith Hospital, Royal Postgraduate Medical School, London, U.K.
Abstract:
Brain MR examinations were performed on one normal and 30 abnormal neonates and infants with a variety of clinical problems using pulsed gradient spin echo (PGSE) sequences sensitized in different directions to detect changes due to anisotropically restricted diffusion of water within the brain. Anisotropically restricted diffusion was demonstrated within white matter, which appeared to be myelinated with T1-weighted inversion recovery or spin echo sequences and within white matter where the presence of myelin was not demonstrated with these sequences. Cysts and fluid collections were recognised by their low signal intensity using PGSE sequences in the subcortical regions, lentiform nuclei, and periventricular regions. An intracerebral hematoma and a subdural hematoma showed a high signal intensity with PGSE sequences consistent with isotropically restricted diffusion. Chronic infarction displayed a low signal intensity consistent with relatively free isotropic diffusion. Patients with leukodystrophy associated with congenital muscular dystrophy showed an anisotropic pattern with different components of the abnormality present on images with sensitization in different directions. The corticospinal tracts failed to show highlighting in three cases where conventional imaging was normal. In several patients with a history of birth asphyxia, asymmetry and a relative reduction in signal intensity were seen in the corticospinal tracts.
Insights
Pulsed gradient spin echo (PGSE) MRI sequences reveal restricted water diffusion in infant brains, aiding in diagnosing conditions like leukodystrophy and birth asphyxia. This technique helps identify abnormalities in white matter and corticospinal tracts.
Area of Science:
- Neuroradiology
- Biomedical Imaging
- Diffusion Tensor Imaging
Background:
- Neonatal and infant brain abnormalities require advanced imaging techniques.
- Understanding water diffusion patterns is crucial for diagnosing white matter diseases.
Purpose of the Study:
- To evaluate the utility of pulsed gradient spin echo (PGSE) MRI sequences in detecting anisotropically restricted water diffusion in infant brains.
- To characterize diffusion patterns in various neuropathological conditions in neonates and infants.
Main Methods:
- Brain MR examinations performed on 31 neonates and infants (1 normal, 30 abnormal).
- Utilized pulsed gradient spin echo (PGSE) sequences sensitized in multiple directions.
- Correlated imaging findings with conventional MRI sequences (T1-weighted inversion recovery, spin echo).
Main Results:
- Demonstrated anisotropically restricted diffusion in myelinated and unmyelinated white matter.
- Identified cysts and fluid collections by low signal intensity on PGSE sequences.
- Showed high signal intensity for hematomas (isotropic diffusion) and low signal for chronic infarction (free isotropic diffusion).
- Leukodystrophy cases exhibited anisotropic patterns dependent on diffusion sensitization direction.
- Corticospinal tract abnormalities detected in birth asphyxia and in cases with normal conventional imaging.
Conclusions:
- PGSE MRI is effective in detecting anisotropically restricted water diffusion in infant brains.
- This technique aids in the diagnosis of white matter abnormalities, congenital disorders, and hypoxic-ischemic injuries.
- PGSE MRI provides valuable insights into the microstructural integrity of the developing brain.