J Korean Med Sci.  2008 Aug;23(4):691-699. 10.3346/jkms.2008.23.4.691.

Experimental Pulmonary Fat Embolism: Computed Tomography and Pathologic Findings of the Sequential Changes

• Woo OH
• Yong HS
• Oh YW
• Shin BK
• Kim HK
• Kang EY

• KMID: 1785831
• DOI: http://doi.org/10.3346/jkms.2008.23.4.691

Abstract

This study was done to demonstrate the computed tomography (CT) and pathologic findings of the sequential changes for experimental pulmonary fat embolism (PFE), and to correlate the CT and pathologic findings of rabbit lung. PFE was induced by an intravenous injection of 0.2 mL linoleic acid in 24 rabbits. The rabbits were divided into 4 groups of 6 rabbits each. CT scans were obtained sequentially at 2 hr (n= 24), day 1 (n=18), day 3 (n=12) and day 7 (n=6) after fat embolization. The pathologic findings were analyzed and CT-pathologic correlation was done. CT scans showed bilateral ground-glass opacity (GGO), consolidation and nodule in all cases. The findings of PFE at 2 hr after fat embolization were areas of decreased attenuation, GGO, consolidation and nodule. These findings were aggravated on the follow- up CT after 1 day and 3 days. The follow-up CT revealed linear density in the subpleural lungs after 7 days. On CT-pathology correlation, wedge-shaped ischemic necrosis in the subpleural lungs correlated with nodule at 2 hr. GGO and consolidation at day 1 on CT correlated with congestion and edema, and these findings at day 3 were correlated with inflammation and hemorrhagic edema. The linear density in the subpleural lungs correlated with interstitial fibrosis and pleural contraction at day 7. In conclusion, PFE was caused by using linoleic acid which is kind of free fatty acid and this study served as one model of the occurrence of nontraumatic PFE. CT accurately depicted the natural evolution of PFE in the serial followup, and this correlated well with the pathologic findings.

Keyword

Embolism, Experimental Studies; Embolism, Fat; Pulmonary Embolism; Lung, Computed Tomography

MeSH Terms

Animals
Embolism, Fat/*pathology/*radiography
Pulmonary Embolism/*pathology/*radiography
Rabbits
*Tomography, X-Ray Computed

Figure

• 

  Fig. 1 CT and pathologic findings of 2 hr (group I) after fat embolization in a rabbit. (A, B) CT scan shows the bilateral ground glass opacity and nodules (arrows) in the subpleural lungs and the areas of decreased attenuation (arrowheads) in the peripheral lung. (C) Photomicrograph shows wedge shaped ischemic necrosis in the subpleural lungs (arrowheads) and mild congestion in the interstitium (H&E stain, × 40). (D) Oil red O stain ( × 400) shows the intravascular fat globule with homogeneous pinkish-colored materials (arrow).

• 

  Fig. 2 CT and pathologic findings of sequential changes at 2 hr and day 1 (group II) after embolization in a rabbit. (A) CT scan obtained 2 hr after embolization shows bilateral multifocal ground glass opacities and consolidations. (B) CT scan obtained day 1 after embolization shows more aggravation of the distribution and the extent of the ground glass opacities and consolidations. (C) Photomicrograph shows the more extensive geographic infarction in the subpleural lungs and prominent congestion and edema (arrowheads) in the interstitium (H&E stain, × 40).

• 

  Fig. 3 CT and pathologic findings of sequential changes at 2 hr, day 1 and day 3 (group III) after fat embolization in a rabbit. (A) The CT scan obtained 2 hr after embolization shows GGO, patchy consoliodations and nodules in the subpleural lungs. (B) The CT findings are more extensive and aggravated at day 3. (C) The gross specimen represents the patchy areas of reddish and brownish discoloration of the surface in the subpleural lungs, and this was correlated with the alveolar hemorrhage and inflammation that was seen microscopically. (D) Photomicrograph shows more extensive inflammation (arrow) with hemorrhage and necrosis (arrowheads) in the interstitium (H&E stain, × 40). (E) Oil red O stain ( × 400) shows extravasated fat globules in the alveolar space or interstitium (arrow) with homogeneous pinkish-colored materials.

• 

  Fig. 4 CT and pathologic findings of sequential changes at 2 hr, day 1, day 3, and day 7 (group IV) after fat embolization in a rabbit. (A) The CT scan obtained 2 hr after embolization shows focal GGO at the subpleural lungs. (B) The CT scan obtained at day 7 after embolization shows resolution of the parenchymal abnormalities and the linear density (arrowheads) in the subpleural lungs. (C) The gross specimen represents the nearly complete resolution of patchy areas of reddish and brownish discoloration of the surface in the subpleural lungs. (D) The photomicrograph shows cord-like fibrosis of the interstitium (arrow) and pleural contraction (H&E stain, × 40). (E) Oil red O stain ( × 400) shows histiocytes with ingestion of fat globules.

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  Fig. 5 Extent of parenchymal abnormality on CT scan of sequential changes after fat embolization in rabbit Lung.

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