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How to Best Detect Hypoxic-Ischemic Encephalopathy in Neonates

April 18, 2008
Written by: , Filed in: Pediatric Radiology
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The objective of a recent study was to compare different MRI techniques and pulse sequences for the depiction of brain injury in neonatal hypoxic-ischemic encephalopathy.

This retrospective study has concluded that the combination of T1- and T2-weighted MR imaging and diffusion-weighted imaging is best for detecting hypoxic-ischemic brain lesions in the early neonatal period.

Methodology
Brain MRI studies in full-term infants who were born between January 2001 and December 2003 who underwent MRI for perinatal asphyxia were selected. All imaging was performed within 10 days after birth. Studies were used if the original neuroradiologist report mentioned hypoxic-ischemic brain injury and normal MRI results. Studies that showed non-acquired brain disease were excluded.

MRIs obtained in the infants were respectively evaluated by two reviewers with a combined experience of 21 years in neuro imaging. The reviewers were made aware of gestational age and age at time of imaging of the infants; however, they were blinded to the infants’ identity and history. The investigators independently studied the hard copies of images with all individual MRI pulse sequences randomly distributed.

By randomly mixing the images, blindness of the investigators was better guaranteed, and influence on the assessment of one pulse sequence with another in the same patient was excluded.

The reviewers assigned a confidence score as definitely abnormal, probably abnormal, equivocal, probably normal, or definitely normal for each pulse sequence. A separate delayed review session took place four weeks after the first session, with both reviewers contemporaneously assessing the images with all sequences of one complete MRI exam displayed together. They reached consensus in all cases, which was then used as a reference standard.

Pediatric Diagnostic Imaging

The Society for Pediatric Radiology
Pediatric Diagnostic Imaging program features the advances and diversity of pediatric imaging by reviewing state-of-the-art clinical material and advanced cutting-edge research presentations. This program presents a group of international experts who discuss state-of-the art diagnostic imaging and the outlook for the future direction of the specialty.
Read more or order:  Pediatric Diagnostic Imaging

Results of the Study
Forty infants were included in the study. Infants were categorized into two groups: those imaged within four days after birth and those imaged after four days of life. The four most prevalent injury patterns in both groups were abnormal signal intensity in the basal ganglia, thalamus, posterior limb of internal capsule, and non-punctate white matter lesions.

For deep gray matter injury, the T1-weighted sequence performed best in both groups. For detection of infarction, diffusion-weighted imaging performed best in both groups. For non-punctate white matter lesions, T2-weighted imaging scored best in the whole group. FLAIR and contrast-enhanced imaging did not contribute to the detection of hypoxic-ischemic brain injury.

Conclusions
A combination of T1- and T2-wighted MRI and diffusion-weighted imaging is best for the detection of hypoxic-ischemic brain injury in the early neonatal period in term-born infants. FLAIR and contrast-enhanced images do not offer a statistically significant diagnostic advantage.

Reviewer’s Comments
What makes this article useful is the specific discussion of separate sequences and their respective strengths in demonstrating pathology indicative of hypoxic-ischemic encephalopathy in neonates. By optimally using only T1-T2 and diffusion-weighted imaging while eliminating the need for FLAIR and contrast-enhanced sequences, the diagnostic performance does not suffer.

Author: Basil Hubbi, MD

Reference
Liauw L, van der Grond J, et al. Hypoxic-Ischemic Encephalopathy: Diagnostic Value of Conventional MR Imaging Pulse Sequences in Term-Born Neonates.
Radiology;
2008; 247 (April): 204-212:

Pediatric Diagnostic Imaging

The Society for Pediatric Radiology
Pediatric Diagnostic Imaging program features the advances and diversity of pediatric imaging by reviewing state-of-the-art clinical material and advanced cutting-edge research presentations. This program presents a group of international experts who discuss state-of-the art diagnostic imaging and the outlook for the future direction of the specialty.
Read more or order:  Pediatric Diagnostic Imaging
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