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Thứ Tư, 23 tháng 1, 2013

JUM 2-2013


1/ Spleen Stiffness and Splenoportal Venous Flow
Assessment Before and After Transjugular Intrahepatic Portosystemic Shunt Placement

Objectives To prospectively assess changes in spleen stiffness and splenoportal venous flow before and after transjugular intrahepatic portosystemic shunt (TIPS) placement.

Methods We prospectively evaluated spleen stiffness measured by the mean shear wave velocity with acoustic radiation force impulse imaging and the splenoportal venous velocity with color Doppler sonography in 12 patients (mean age ± SD, 42.6 ± 11.0 years; range, 29–65 years) who underwent TIPS placement for portal hypertension and gastroesophageal bleeding. The mean shear wave velocity and angle-corrected splenoportal venous velocity at the main portal and splenic veins were measured 1 day before and 3 to 9 days after TIPS placement (mean interval, 6.0 ± 1.95 days; range, 4–10 days) and were compared with portal vein pressure measured during the procedure.

Results There was a significant difference in portal vein pressure before and after TIPS (25.34 ± 6.21 versus 15.66 ± 6.07 mm Hg; P = .0005). After TIPS, the mean shear wave velocity decreased significantly in all 12 cases (3.50 ± 0.46 versus 3.15 ± 0.39 m/s before and after TIPS; P = .00015). The flow velocity at the main portal vein increased significantly after TIPS (22.21 ± 4.13 versus 47.25 ± 12.37 cm/s; P = .0000051). The splenic vein velocity and spleen index measured 25.57 ± 6.98 cm/s and 55.99 ± 21.27 cm2, respectively, before TIPS and 35.72 ± 11.10 cm/s and 50.11 ± 21.12 cm2 after TIPS (P = .0004 and .003).

Conclusions A significant decrease in the mean shear wave velocity and increase in the splenoportal venous velocity occurred with reduced portal vein pressure after TIPS placement. Hence, both parameters can be used as noninvasive quantitative markers for monitoring TIPS function after placement.

o    Received May 17, 2012.
o    Revision received June 6, 2012.
o    Accepted July 2, 2012.
o    ©2013 by the American Institute of Ultrasound in Medicine

2/ Value of the Ultrasound Attenuation Index for Noninvasive Quantitative Estimation of Hepatic Steatosis

Objectives To assess the value of the ultrasound (US) attenuation index for noninvasive estimation of hepatic steatosis and determine its optimal cutoff value for severe steatosis in potential living liver donors.

Methods Two hundred forty potential donors underwent US-guided biopsy. The target site was scanned at 4 and 8 MHz. On the sonogram, the observer drew 3 × 3-mm square regions of interest in superficial (3-cm) and deep (5-cm) areas. The attenuation index was defined as the difference between superficial and deep echogenicity/superficial echogenicity × 100. On biopsy specimens, replacement of hepatic parenchyma was evaluated on a percentage scale. Severe steatosis was defined as macrovesicular fatty change of 30% or greater. Spearman rank correlation (ρ) was used to determine correlation coefficients between the attenuation index and steatosis degree; receiver operating characteristic analysis was performed to determine the optimal attenuation index cutoff value for severe steatosis.

Results The median steatosis degree was 3% (interquartile range [IQR], 0%–10%). Severe steatosis was found in 10 donors. The attenuation index ranged from –27.4 to 36.6 (median, 4.0; IQR, –1.6–10.4) at 4 MHz and –18.0 to 78.1 (median, 14.5; IQR, 7.2–21.9) at 8 MHz. There was a minimal positive correlation between steatosis and the attenuation index at 4 MHz (total steatosis: ρ = 0.339; P < .001; macrovesicular steatosis: ρ = 0.360; P < .001). However, there was a significant moderate correlation between steatosis and the attenuation index at 8 MHz (total steatosis: ρ = 0.669; P < .001; macrovesicular steatosis: ρ = 0.645; P < .001). The optimal attenuation index cutoff value for severe steatosis at 8 MHz was 31.0.

Conclusions The US attenuation index at 8 MHz is a useful indicator for noninvasive quantitative estimation of hepatic steatosis and diagnosis of severe steatosis in potential living liver donors.

o    Received June 1, 2012.
o    Revision received June 25, 2012.
o    Accepted July 19, 2012.
o    ©2013 by the American Institute of Ultrasound in Medicine

3/ Role of Acoustic Shear Wave Velocity Measurement in Characterization of Breast Lesions

Objectives To analyze the value of acoustic radiation force impulse imaging quantification in characterization of breast lesions and to analyze the stiffness of glandular and subcutaneous fatty tissue in benign and malignant lesions.

Methods A total of 175 breast lesions (67 malignant and 108 benign) in 173 women were studied. With acoustic radiation force impulse imaging, shear wave velocity (SWV), which can reflect the stiffness of tissue, was measured within the lesion (internal SWV [SWVi]), in the boundary zone (boundary SWV [SWVb]), in normal-appearing glandular tissue (glandular SWV [SWVg]), and in subcutaneous fatty tissue (fatty SWV [SWVf]). All lesions underwent core needle biopsy or surgical excision. Differences among the SWV types in malignant and benign lesions were evaluated. We also assessed how different lesion types affected the SWV types. Receiver operating characteristic analysis was performed to assess the sensitivity and specificity of the SWV types in differentiating malignant from benign lesions.

Results Internal SWV was significantly higher than SWVb, SWVg, and SWVf; SWVb was significantly higher than SWVg and SWVf; and SWVg was significantly higher than SWVf in both malignant and benign groups (P < .05). All 4 SWV types were significantly higher in the malignant group than the benign group (P < .05). In the malignant group, grade 3 invasive ductal carcinoma had the highest SWVi. The sensitivity and specificity for differentiating malignant lesions were 55.2% and 95.8% for SWVi, 85.1% and 53.3% for SWVb, 68.2% and 69.6% for SWVg, and 67.2% and 66.0% for SWVf.

Conclusions Acoustic radiation force impulse imaging has potential to characterize breast lesions, both internally and within the boundary zone, and to reflect changes in stiffness within surrounding glandular and subcutaneous fatty tissues caused by malignant tumors.

o    Received February 24, 2012.
o    Revision received March 17, 2012.
o    Accepted July 19, 2012.
o    ©2013 by the American Institute of Ultrasound in Medicine

4/ Small Liver Nodule Detection With a High-Frequency Transducer in Patients With Chronic Liver Disease
Report of 3 cases

We report 3 cases in which small liver lesions were revealed on sonography with the supplemental use of a high-frequency transducer. In all 3 cases, the patients had cirrhosis or chronic liver disease. The lesions were not seen on computed tomography or magnetic resonance imaging. Sonography plays a pivotal role in surveillance for hepatocellular carcinoma and, with modern transducer technology, may be the first imaging modality to show an early small tumor. A more thorough search for focal liver lesions with adjunctive use of high-frequency transducers may prolong the examination time but can improve surveillance for hepatocellular carcinoma.

o    Received February 7, 2012.
o    Revision received March 27, 2012.
o    Accepted July 12, 2012.
o    ©2013 by the American Institute of Ultrasound in Medicine

5/ Segmental Testicular Infarction
Sonographic Findings and Pathologic Correlation

Segmental testicular infarction can mimic testicular carcinoma on sonography and can lead to unnecessary orchiectomy. This case series describes and correlates sonographic and histologic findings of 7 pathologically proven segmental testicular infarction cases. Segmental testicular infarction should be suspected on sonography when a geographic lesion with low or mixed echogenicity has absent or near-absent flow in a patient with scrotal pain. A hyperechoic rim and peripheral hyperemia correspond to interstitial hemorrhage and inflammatory changes. As an infarct evolves, it becomes more discrete and hypoechoic as ghost outlines replace seminiferous tubules. Follow-up or contrast-enhanced magnetic resonance imaging or sonography can increase diagnostic confidence in suspected cases and prevent unnecessary orchiectomy.

o    Received May 29, 2012.
o    Revision received June 14, 2012.
o    Accepted July 8, 2012.
o    ©2013 by the American Institute of Ultrasound in Medicine

 

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