Diffusion-Weighted Imaging of Acute Corticospinal Tract Injury Preceding Wallerian Degeneration in the Maturing Human Brain
Avi Mazumdara,
Pratik Mukherjeeb,
Jeffrey H. Millera,
Hiten Maldea and
Robert C. McKinstrya
a Neuroradiology Section, Mallinckrodt Institute of Radiology, St. Louis Children’s Hospital, Washington University Medical Center
b Neuroradiology Section, Department of Radiology, University of California, San Francisco
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FIG 1. Patient 1 was a 4-day-old neonate with a right MCA infarct, which occurred 4 days before MR imaging was performed. At 3- and 6-month clinical follow-up, the patient had clinical progression of the left hemiparesis, consistent with the evolution of Wallerian degeneration.
Far left, Transverse (top) and coronal (bottom) fast spin-echo T2-weighted images (5000/96 [TR/TE]) show abnormal signal intensity in the right corticospinal tract (arrowhead). Increased signal intensity is present in the region of the right temporal lobe subcortical white matter (black arrow, top), along with areas of decreased signal intensity in the cortical gray matter (black arrows, bottom). A focus of hemorrhage (white arrow) is seen in the corona radiata.
Middle left, Transverse (top) and coronal (bottom) DW imagess (4000/100) acquired with a spin-echo echo-planar imaging technique show increased signal intensity in the right cerebral peduncle (arrowhead) and subcortical white matter in the territorial infarct (arrow).
Middle right, Corresponding transverse (top) and coronal (bottom) ADC maps and reduced ADC in the right cerebral peduncle (arrowhead) and subcortical white matter in the territorial infarct (arrow).
Far right, Transverse DW image (top) and corresponding ADC map (bottom) show involvement of the splenium of the corpus callosum (arrowhead).
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FIG 2. Patient 2 was an 8-day-old neonate with a skull fracture after forceps delivery. Transverse images obtained at days 2, 4, and 8.
Top row, T2-weighted images acquired with a fast spin-echo technique (5000/96) show an area of hemorrhage with surrounding edema in the left frontal lobe (arrow). At 4 and 8 days, progressive development of the increased signal intensity in the left cerebral peduncle is seen (arrowhead).
Middle row, DW images obtained by using a spin-echo echo-planar imaging sequence (3000/106) show areas of increased signal intensity in the right frontal, right temporal, left frontal lobes, as well as in the left frontopontine tract (arrowhead). Also shown is the area of hemorrhage with surrounding edema in the left frontal lobe (arrow).
Bottom row, ADC maps confirm truly reduced diffusion in the left cerebral peduncle (arrowhead). Interestingly the diffusion changes in the left frontal lobe subcortical white matter become less apparent on days 4 and 8, consistent with ADC pseudonormalization.
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FIG 3. Patient 3 was an 8-week-old female infant with a history of seizures that started 3 days before MR imaging was performed. DW imaging had shown a left MCA distribution infarct (not shown). The patient had decreased tone in the right arm at the time of her discharge from the hospital 3 weeks after initial injury; the patient’s initial clinical presentation did not change.
A, Normal transverse fast spin-echo T2-weighted image (5000/96) shows the left cerebral peduncle.
B, Transverse DW image acquired with a spin-echo echo-planar imaging technique (4000/100) shows increased signal intensity in the left cerebral peduncle (arrow).
C, Corresponding ADC map demonstrates that the ADC value in the left cerebral peduncle (arrow) is lower that that in the normal right cerebral peduncle.
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FIG 4. Patient 6 was a 5-day-old neonate with hypoxic encephalopathy.
A, Transverse turbo spin-echo T2-weighted image (5000/96) shows diffusely increased signal intensity in the subcortical white matter in both cerebral hemispheres, with increased signal intensity in both cerebral peduncles (arrows).
B, Transverse DW image acquired with a spin-echo echo-planar technique (4000/100) shows diffusely increased signal intensity in the subcortical white matter and both cerebral peduncles (arrows).
C, Transverse ADC map confirms the finding shown in B (arrows).
D, Coronal T2-weighted image acquired with a turbo spin-echo technique shows no evidence of corticospinal tract injury.
E, Coronal DW image acquired with a spin-echo echo-planar technique (4000/100) shows bilateral corticospinal tract injury (arrows).
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