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AJNR - American Journal of Neuroradiology

A, Axial T2-weighted image, 3300/105/1 (TR/TE/excitations), obtained within 3 hours of cardiac arrest, shows the cerebellum to be of normal appearance.

B, Corresponding high-strength diffusion-weighted image, 0.8/123/1100 (TR/TE/B value), shows that the cerebellum (c) is diffusely bright when compared with the left occipital lobe (o).

C, Follow-up image obtained 3 days after anoxic episode. Midsagittal T1-weighted image (570/15/1) shows swollen cerebellum with upward transtentorial and downward transforaminal herniations. The forth ventricle and brain stem are compressed.

D, Axial T2-weighted image (3500/93/1), obtained at same time as the image shown in C, shows swollen and bright cortex, effaced cortical sulci, and bright basal ganglia. Because of technical problems, diffusion-weighted images were not obtained as part of the follow-up study. This patient died.

A, Axial high-strength diffusion-weighted image (0.8/123/1100), obtained less than 3 hours after cardiac arrest (because of electrocution), shows abnormal brightness in lentiform nuclei (arrows). Brightness in splenium of corpus callosum is normal because transverse white matter fibers are perpendicular to the plane (z) in which the diffusion gradient was applied.

B, Axial T2-weighted image (4200/105/1), obtained 3 days after insult, shows increased signal intensity in basal ganglia and possibly in occipital cortices.

C, High-strength diffusion-weighted image (0.8/123/1100), obtained at same time as the image shown in B, reveals abnormally bright basal ganglia and cortex in frontal, posterior temporal, and occipital lobes.

D, High-strength diffusion-weighted image (0.8/123/1100), obtained at same time as the image shown in B, shows that the cortex in the frontal and parietal regions is abnormally bright.

E, High-strength diffusion-weighted image (0.8/123/1100), obtained 14 days after insult and corresponding to the image shown in C, reveals decreasing signal intensity from gray matter structures and abnormal brightness in posterior limb of internal capsules.

F, Axial high-strength diffusion-weighted image (0.8/123/1100), obtained at the same time as the image shown in E and at same level as the image shown in D, reveals decreasing signal intensity from the cortex and abnormal brightness in the centra semiovale.

G, Corresponding conventional T2-weighted image (4500/105/1) shows normal results. This patient survived.

A, Axial T2-weighted image (4500/105/1) shows questionable increased signal intensity in basal ganglia.

B, Corresponding low-strength diffusion-weighted image (0.8/123/30) shows no abnormality.

C, Corresponding high-strength diffusion-weighted image (0.8/123/1100) shows abnormally bright basal ganglia, thalami, and cortex (particularly in medial-occipital regions).

D, More cephalad axial low-strength diffusion-weighted image (0.8/123/30) shows no abnormality.

E, Corresponding high-strength diffusion-weighted image (0.8/123/1100) shows abnormally bright cortex surrounding the central sulci. This patient survived.

A, Axial T2-weighted image (4500/105/1) initially was interpreted as normal. A careful retrospective analysis raised the possibility of increased signal intensity and thickening of the cortex.

B, Corresponding high-strength diffusion-weighted image (0.8/123/1100) shows abnormal brightness preferentially involving the cortex.

FIG 5. Images of abnormal white matter obtained during the late subacute period (15–20 days).

A, Axial T2-weighted image (3300/105/1) shows no definite abnormalities. There is subtle and nonspecific increased signal intensity in the white matter.

B, Corresponding high-strength diffusion-weighted image (0.8/123/1100) shows abnormally bright white matter in centra semiovale and no definite cortical abnormalities.

FIG 6. Images of laminar necrosis obtained during the chronic period.

A, Axial T1-weighted image (550/15/1) shows linear brightness along the superior frontal, pre-central, and central gyri corresponding to the sequelae of laminar necrosis 22 days after cardiac arrest.

B, Axial high-strength diffusion-weighted image (0.8/123/1100), obtained inferior to the image shown in A (convexity diffusion images were degraded by magnetic susceptibility artifacts), shows normal results.