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Updated: Dec 11, 2025
Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants
Published on: March 14, 2013
Feasibility of oscillating and pulsed gradient diffusion MRI to assess neonatal hypoxia-ischemia on clinical systems
Fusheng Gao1, Xiaoxia Shen2, Hongxi Zhang1
1Department of Radiology, Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou, China.
Abstract:
Diffusion-time- (t) dependent diffusion MRI (dMRI) extends our ability to characterize brain microstructure by measuring dMRI signals at varying t. The use of oscillating gradient (OG) is essential for accessing short t but is technically challenging on clinical MRI systems. This study aims to investigate the clinical feasibility and value of t-dependent dMRI in neonatal hypoxic-ischemic encephalopathy (HIE). Eighteen HIE neonates and six normal term-born neonates were scanned on a 3 T scanner, with OG-dMRI at an oscillating frequency of 33 Hz (equivalent t ≈ 7.5 ms) and pulsed gradient (PG)-dMRI at a t of 82.8 ms and b-value of 700 s/mm2. The t-dependence, as quantified by the difference in apparent diffusivity coefficients between OG- and PG-dMRI (ΔADC), was observed in the normal neonatal brains, and the ΔADC was higher in the subcortical white matter than the deep grey matter. In HIE neonates with severe and moderate injury, ΔADC significantly increased in the basal ganglia (BG) compared to the controls (23.7% and 10.6%, respectively). In contrast, the conventional PG-ADC showed a 12.6% reduction only in the severe HIE group. White matter edema regions also demonstrated increased ΔADC, where PG-ADC did not show apparent changes. Our result demonstrated that t-dependent dMRI provided high sensitivity in detecting moderate-to-severe HIE.
Insights
Diffusion-time dependent diffusion MRI (dMRI) shows promise for detecting neonatal hypoxic-ischemic encephalopathy (HIE). This advanced technique offers higher sensitivity than conventional dMRI in identifying injury, even in moderate cases.
Area of Science:
- Neuroimaging
- Medical Physics
- Neonatal Medicine
Background:
- Diffusion MRI (dMRI) characterizes brain microstructure by measuring signal changes over diffusion time (t).
- Oscillating gradient (OG) dMRI enables measurements at short diffusion times, crucial for microstructural insights but challenging clinically.
- Neonatal hypoxic-ischemic encephalopathy (HIE) is a serious condition requiring sensitive diagnostic tools.
Purpose of the Study:
- To assess the clinical feasibility and diagnostic value of diffusion-time dependent dMRI in neonatal HIE.
- To compare the sensitivity of diffusion-time dependent dMRI with conventional pulsed gradient (PG)-dMRI in HIE detection.
Main Methods:
- Acquired OG-dMRI (t ≈ 7.5 ms) and PG-dMRI (t = 82.8 ms, b=700 s/mm²) data from 18 HIE neonates and 6 controls on a 3T scanner.
- Quantified diffusion-time dependence using the difference in apparent diffusion coefficients (ΔADC) between OG- and PG-dMRI.
- Analyzed ΔADC and conventional PG-ADC in different brain regions, including basal ganglia and white matter edema.
Main Results:
- Diffusion-time dependence (ΔADC) was observed in normal neonates, higher in subcortical white matter than deep gray matter.
- HIE neonates showed significantly increased ΔADC in basal ganglia compared to controls (severe: 23.7%, moderate: 10.6%).
- Conventional PG-ADC only showed reduction in severe HIE, while increased ΔADC detected changes in white matter edema where PG-ADC was unchanged.
Conclusions:
- Diffusion-time dependent dMRI is highly sensitive for detecting moderate-to-severe HIE.
- This advanced dMRI technique provides valuable microstructural information in neonatal brain injury.
- OG-dMRI offers a promising clinical approach for improved HIE diagnosis.
