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Chủ Nhật, 26 tháng 5, 2013

RADIOLOGY 6-2013


US Elastography–derived Shear Wave Velocity Helps Distinguish Acutely Inflamed from Fibrotic Bowel in a Crohn Disease Animal Model

Purpose: To determine if acoustic radiation force impulse elastography-derived bowel wall shear wave velocity (SWV) allows distinction of acutely inflamed from fibrotic intestine in a Crohn disease animal model.

Materials and Methods: University Committee on the Use and Care of Animals approval was obtained. An acute inflammation Crohn disease model was produced by treating eight Lewis rats with a single administration of trinitrobenzenesulfonic acid (TNBS) enema, with imaging performed 2 days later in the surviving six rats. Colonic fibrosis in an additional eight Lewis rats was achieved by administering repeated TNBS enemas during 4 weeks, with imaging performed in the surviving seven rats 7 days later to allow acute inflammation resolution. Nine transcutaneous bowel wall SWV measurements were obtained from the colon in all rats without and with applied strain. Mean SWVs without and with applied strain were compared between animal cohorts by using the Student t test, and receiver operating characteristic (ROC) curves were created to assess diagnostic performance.

Results: Mean bowel wall SWVs were significantly higher for fibrotic versus acute inflammation cohort of rats at 0% (3.4 ± 1.1 vs 2.3 ± 0.5 m/sec; P = .047) and 30% (6.3 ± 2.2 vs 3.6 ± 0.9 m/sec; P = .02) applied strain. Both acute inflammation and fibrotic cohort of rats demonstrated linear increases in mean SWV with increasing applied strain, with significantly different mean slopes (P = .02) and y-intercepts (P = .02). The area under the ROC curve of the SWV ratio (mean SWV/applied strain) for differentiating histopathologically confirmed fibrotic from inflamed bowel was 0.971.

Conclusion: Bowel wall SWV helps distinguish acutely inflamed from fibrotic intestine in a Crohn disease animal model.

© RSNA, 2013

Achilles Tendon Assessed with Sonoelastography: Histologic Agreement

Purpose: To compare and determine the level of agreement of findings at conventional B-mode ultrasonography (US) and sonoelastography of the Achilles tendon with findings at histologic assessment.

Materials and Methods: This study was conducted with the approval of the institutional review boards, and all cadavers were in legal custody of the study institution. Thirteen Achilles tendons in 10 cadavers (four male, six female; age range, 70–90 years) were examined with B-mode US and sonoelastography. B-mode US grading was as follows: Grade 1 indicated a normal-appearing tendon with homogeneous fibrillar echotexture; grade 2, a focal fusiform or diffuse enlarged tendon; and grade 3, a hypoechoic area with or without tendon enlargement. Sonoelastography grading was as follows: Grade 1 indicated blue (hardest) to green (hard); grade 2, yellow (soft); and grade 3, red (softest). Twenty-five biopsy specimens from representative lesions of the middle and distal thirds of the Achilles tendons were evaluated histologically. The concordance of B-mode US grading compared with sonoelastographic grading was assessed by using κ analysis.

Results: With B-mode US and sonoelastography, all 11 tendon thirds of histologically normal tendons were verified as normal (grade 1). Sonoelastography depicted 14 of 14 (100%) tendon thirds with histologic degeneration (grade 2 or 3), whereas B-mode US could depict only 12 of 14 (86%) lesions (grade 2 or 3). Only moderate agreement between B-mode US and sonoelastography was seen (κ = 0.52, P < .001).

Conclusion: Sonoelastography might help predict signs of histopathologic degeneration of Achilles tendinosis, potentially more sensitively than B-mode US.

© RSNA, 2013

 

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