Experimental Cerebral Fat Embolism: Embolic Effects of Triolein and Oleic Acid Depicted by MR Imaging and Electron Microscopy
Hak Jin Kima,
Jong Hwa Leef,
Chang Hun Leeb,
Suk Hong Leea,
Tae Yong Moona,
Byung Mann Choc,
Hae Kyu Kimd,
Byung Rae Parke and
Kee Hyun Changg
a Department of Radiology, Pusan National University College of Medicine, Korea
b Department of Pathology, Pusan National University College of Medicine, Korea
c Department of Preventive Medicine, Pusan National University College of Medicine, Korea
d Department of Anesthesiology, Pusan National University College of Medicine, Korea
e the Interdisciplinary Program in the Department of Biomedical Engineering, Pusan National University College of Medicine, Korea
f Department of Radiology, Ulsan University Hospital, Korea
g Department of Radiology, Seoul National University College of Medicine, Korea
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FIG 1. Group 1. MR images obtained 2 hours after cat brains were embolized with triolein show type 1 (solid arrow) and type 2 (open arrows) lesions. Type 2 lesions are bigger than type 1 lesions.
A, T2-weighted (3000/96/2 [TR/TE/NEX]) image. Type 1 and type 2 lesions are hyperintense.
B, Contrast-enhanced T1-weighted (320/30/2) image. Type 1 lesions show mild enhancement. Type 2 lesions show enhancement.
C, Diffusion-weighted image. Type 1 lesions are hyperintense. Type 2 lesions have isointensity or slight hyperintensity.
D, ADC map. Type 1 lesions are hypointense. Type 2 lesions are isointense.
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FIG 2. Group 2. MR images obtained 2 hours after cat brains were embolized with oleic acid group show type 1 (solid arrow) and type 2 (open arrows) lesions.
A, T2-weighted (3000/96/2) image. Type 1 lesions have mild hyperintensity. Type 2 lesions are hyperintense.
B, Contrast-enhanced T1-weighted (320/30/2) image. Type 1 lesions show less enhancement than do type 2 lesions, which show strong enhancement.
C, Diffusion-weighted image. Type 1 lesions are hyperintense. Type 2 lesions have isointensity or mild hyperintensity.
D, ADC map. Type 1 lesions are hypointense. Type 2 lesions are isointense.
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FIG 3. Bar graph of the signal intensity ratios on T2-weighted images. At 2 hours, the ratios in type 1 and type 2 lesions increase significantly in both groups (P < .001). The ratios of type 1 lesions are significantly higher in group 2 compared with group 1 at both 30 minutes and 2 hours (P = .013). However, in type 2 lesions, the ratios do not significantly differ in either group at either time (P > .643).
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FIG 4. Bar graph of the signal intensity ratios on the ADC maps. Compared with the baseline value at 30 minutes, the ratios in types 1 and type 2 lesions did not change significantly at 2 hours in either group (P > .485). With the type 1 lesions, the ratios in group 2 were significantly lower than those in group 1 at each time point (P = .027). However, in type 2 lesions, the ratios were not significantly different in either group (P > .144).
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FIG 5. Bar graph of the signal intensity ratios on contrast-enhanced T1-weighted images. Compared with the baseline values at 30 minutes, the ratios in type 1 lesions increase significantly at 2 hours in both groups (P = .034). In type 1 lesions, the ratios are not significantly different between group 1 and 2 at each time point (P > .051). However, in type 2 lesion, the ratios in group 1 are higher than those in group 2 at each time point (P < .001).
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FIG 6. Electron microscopy findings in a type 1 lesion in a cat brain from group 1, which was treated with triolein (original magnification x3000). Photomicrograph shows an intravascular fat vacuole (F) and defects in the endothelial wall (solid arrows). Areas of perivascular interstitial edema (asterisk) and neuropil swelling (arrowhead) are smaller than 5 µm in diameter. Open arrows represent red blood cells. Bar indicates 2 µm.
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FIG 7. Electron microscopy findings in a type 1 lesion in a cat brain from group 1, which was treated with triolein (original magnification x5000). The huge intravascular fat vacuole (F) distends the lumen and compresses the endothelial wall. The endothelial wall (arrows) is partly disrupted. Widening of the perivascular interstitial space (asterisks) is mild. Bar indicates 1 µm.
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FIG 8. Electron microscopy findings in a type 1 lesion in a cat brain from group 2, which was treated with oleic acid (original magnification x4000). Neuropil cells (arrowheads) are edematous, and widening of the interstitial space (asterisk) is prominent. Bar indicates 2 µm.
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FIG 9. Electron microscopy findings in a type 1 lesion in a cat brains from group 2, which was treated with oleic acid (original magnification x5000). A 5-µm intravascular fat vacuole (F) is shown. Neuropil swelling (arrowheads) is prominent, and widening of the perivascular interstitial space (asterisk) is also observed. Bar indicates 1 µm.
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