Woo Kyoung Jeong

Principles and clinical application of ultrasound elastography for diffuse liver disease

Accurate assessment of the degree of liver fibrosis is important for estimating prognosis and deciding on an appropriate course of treatment for cases of chronic liver disease (CLD) with various etiologies. Because of the inherent limitations of liver biopsy, there is a great need for non-invasive and reliable tests that accurately estimate the degree of liver fibrosis. Ultrasound (US) elastography is considered a non-invasive, convenient, and precise technique to grade the degree of liver fibrosis by measuring liver stiffness. There are several commercial types of US elastography currently in use, namely, transient elastography, acoustic radiation force impulse imaging, supersonic shear-wave imaging, and real-time tissue elastography. Although the low reproducibility of measurements derived from operator-dependent performance remains a significant limitation of US elastography, this technique is nevertheless useful for diagnosing hepatic fibrosis in patients with CLD. Likewise, US elastography may also be used as a convenient surveillance method that can be performed by physicians at the patients’ bedside to enable the estimation of the prognosis of patients with fatal complications related to CLD in a non-invasive manner.

Shear-Wave Elastography: A Noninvasive Tool for Monitoring Changing Hepatic Venous Pressure Gradients in Patients with Cirrhosis

PURPOSE To investigate whether liver stiffness ( LS liver stiffness ) and change in LS liver stiffness measurements ( ΔLS change in LS ) at shear-wave elastography ( SWE shear-wave elastography ) correlates with the hepatic venous pressure gradient ( HVPG hepatic venous pressure gradient ) and to assess the feasibility of using SWE shear-wave elastography to estimate the change in HVPG hepatic venous pressure gradient ( ΔHVPG change in HVPG ) in patients with portal hypertension. MATERIALS AND METHODS Institutional review board approval was obtained, with waiver of informed consent. Between September 2010 and October 2012, 97 consecutive patients who were given a diagnosis of portal hypertension on the basis of HVPG hepatic venous pressure gradient measurement were included. Among these patients, 23 who underwent follow-up HVPG hepatic venous pressure gradient measurement to evaluate response to treatment were included in the follow-up group. The correlation between HVPG hepatic venous pressure gradient and LS liver stiffness was analyzed by using the Pearson correlation test. In the follow-up group, whether ΔHVPG change in HVPG was correlated with ΔLS change in LS was also evaluated. Thereafter, the areas under the receiver operating characteristic curves ( AUC area under the ROC curve s) were calculated to determine the diagnostic performances of ΔLS change in LS and the second LS liver stiffness measurement after medical treatment and to compare their performances in association with clinical improvement and aggravation of portal hypertension. RESULTS LS liver stiffness was moderately correlated with HVPG hepatic venous pressure gradient (r = 0.593) in the single-measurement group. There was also a strong correlation between ΔLS change in LS and ΔHVPG change in HVPG (r = 0.863). At comparison of the second LS liver stiffness measurement, ΔLS change in LS showed no significant difference in AUC area under the ROC curve in patients with improvement (0.627 vs 0.794, P = .201) but showed higher AUC area under the ROC curve in association with aggravation of portal hypertension (0.925 vs 0.611, P = .026). CONCLUSION Estimating ΔHVPG change in HVPG by using SWE shear-wave elastography may be useful in patients with cirrhosis and portal hypertension.

Evaluation of portal hypertension by real-time shear wave elastography in cirrhotic patients.

To assess the correlation between liver stiffness measurement (LSM) by real‐time shear wave elastography (SWE) and hepatic venous pressure gradient (HVPG) and to investigate the diagnostic performance of SWE for predicting clinically significant and severe portal hypertension (CSPH and SPH).

Right Lobe Estimated Blood-free Weight for Living Donor Liver Transplantation: Accuracy of Automated Blood-free CT Volumetry-Preliminary Results

PURPOSE To determine the relative accuracy of automated blood-free to blood-filled computed tomographic (CT) volumetry for estimation of right-lobe weight in living donor liver transplantation. MATERIALS AND METHODS This retrospective study was approved by the institutional review board; informed consent was waived. Between October 1, 2008, and April 30, 2009, 88 live liver donors (54 men, 34 women; mean age, 26.1 years +/- 6.9 [standard deviation]) who underwent CT and had their right lobes procured in the study institution were included. Automated measurement of blood-filled volume (V(BFill)) and blood-free volume (V(BFree)) of the right lobe was performed by using 16-row multidetector CT performed with 5-mm intervals. Actual hepatic weight was measured blood free during surgery. Percentage blood volume, %V(B), was calculated as follows: %V(B) = V(BFill) - V(BFree)/V(BFill) . 100. Pearson tests were performed to determine correlation coefficients between V(BFill)/1.22 or V(BFree) and weight. Percentage deviation and percentage absolute deviation of V(BFree) from weight were compared with those of V(BFill)/1.22 by using a paired t test or Wilcoxon rank sum test. Regression analysis was performed between V(BFree) and weight. RESULTS Mean V(BFill), V(BFree), and weight were 789.0 mL +/- 126.4, 713.9 mL +/- 114.4, and 717.8 g +/- 110.4. Percentage blood volume varied from 6.5% to 19.8% (mean, 9.5%). Compared with weight, the correlation coefficient was slightly higher with V(BFree) (r = 0.9140) than with V(BFill)/1.22 (r = 0.8909). Mean percentage deviation and percentage absolute deviation were significantly smaller with V(BFree) (-0.4% +/- 6.3, 5.0% +/- 3.8; P < .001) than with V(BFill)/1.22 (-9.8% +/- 6.5, 10.2% +/- 7.3; P < .001). The equation relating V(BFree) and weight, W, was as follows: W = (0.8815 . V(BFree)) + 88.5117, with R(2) of 0.8355 (P < .001). CONCLUSION At automated CT volumetry in live liver donors, the percentage blood volume varies. The V(BFree) is more accurate than is V(BFill)/1.22 in estimation of hepatic weight.

Real time shear wave elastography in chronic liver diseases: accuracy for predicting liver fibrosis, in comparison with serum markers.

AIM To evaluate the correlation between liver stiffness measurement (LSM) by real-time shear wave elastography (SWE) and liver fibrosis stage and the accuracy of LSM for predicting significant and advanced fibrosis, in comparison with serum markers. METHODS We consecutively analyzed 70 patients with various chronic liver diseases. Liver fibrosis was staged from F0 to F4 according to the Batts and Ludwig scoring system. Significant and advanced fibrosis was defined as stage F ≥ 2 and F ≥ 3, respectively. The accuracy of prediction for fibrosis was analyzed using receiver operating characteristic curves. RESULTS Seventy patients, 15 were belonged to F0-F1 stage, 20 F2, 13 F3 and 22 F4. LSM was increased with progression of fibrosis stage (F0-F1: 6.77 ± 1.72, F2: 9.98 ± 3.99, F3: 15.80 ± 7.73, and F4: 22.09 ± 10.09, P < 0.001). Diagnostic accuracies of LSM for prediction of F ≥ 2 and F ≥ 3 were 0.915 (95%CI: 0.824-0.968, P < 0.001) and 0.913 (95%CI: 0.821-0.967, P < 0.001), respectively. The cut-off values of LSM for prediction of F ≥ 2 and F ≥ 3 were 8.6 kPa with 78.2% sensitivity and 93.3% specificity and 10.46 kPa with 88.6% sensitivity and 80.0% specificity, respectively. However, there were no significant differences between LSM and serum hyaluronic acid and type IV collagen in diagnostic accuracy. CONCLUSION SWE showed a significant correlation with the severity of liver fibrosis and was useful and accurate to predict significant and advanced fibrosis, comparable with serum markers.

Heterotopic ossification developing in surgical incisions of the abdomen: analysis of its incidence and possible factors associated with its development.

Objective: To analyze the incidence of heterotopic ossification (HO) development in incision scars after abdominal surgery and to search for factors relating with its development. Methods: We retrospectively analyzed the postoperative computed tomographic scans of 152 consecutive patients who underwent abdominal incisions, recording the presence of ossification and its characteristics, the type of surgery and incision, and characteristics of the xiphoid process. The change in size upon follow-up was also evaluated. Results: Heterotopic ossifications were identified in 39 patients (25.7%). They were most commonly located in the linea alba (n = 29 [74.4%]) and associated with upper midline incisions (n = 30 [76.9%]). Twenty-four of the 29 patients who underwent postoperative computed tomography twice at least demonstrated changes in size, with decreases in 21 patients. The HO had completely disappeared in 2 patients. Conclusions: The development of HOs in abdominal incisions is a common finding and may be self-limiting. The upper midline incision seems to affect its incidence not uniquely.

Hepatic Outflow Obstruction at Middle Hepatic Vein Tributaries or Inferior Right Hepatic Veins After Living Donor Liver Transplantation with Modified Right Lobe Graft: Comparison of CT and Doppler Ultrasound

OBJECTIVE The objective of our study was to compare CT and Doppler ultrasound in the diagnosis of hepatic outflow obstruction at the middle hepatic vein (MHV) tributaries and inferior right hepatic veins (RHVs) after living donor liver transplantation (LDLT) with modified right lobe grafts. MATERIALS AND METHODS Thirty-seven venographies were performed in 36 patients after LDLT with modified right lobe grafts, evaluating 51 MHV tributaries and 25 inferior RHVs. They were classified as obstructed or nonobstructed. On Doppler ultrasound or CT, flow patterns of the MHV tributaries and inferior RHVs or the relative parenchymal attenuation, enhancement, and opacification of these veins were evaluated for the diagnosis of hepatic outflow obstruction. McNemar tests were performed to compare the diagnostic values of Doppler ultrasound and CT. RESULTS On the basis of hepatic venography, 33 MHV tributaries were categorized as obstructed and 18 as nonobstructed, and 16 inferior RHVs were categorized as obstructed and nine as nonobstructed. For the diagnosis of MHV tributary obstruction, Doppler ultrasound was more sensitive and accurate, although less specific, than CT (97% vs 39%, respectively, p < 0.001; 86% vs 61%, p = 0.0209; 67% vs 100%, p = 0.0412). Similarly, Doppler ultrasound was more sensitive (94% vs 31%, respectively) and accurate (84% vs 56%) than CT, although less specific (67% vs 100%), for the diagnosis of inferior RHV obstruction, with a statistical significance only for sensitivity (p = 0.002, 0.092, and 0.248, respectively). CONCLUSION Doppler ultrasound is more sensitive and accurate than CT for the detection of obstruction at the MHV tributaries and inferior RHVs in patients after LDLT using modified right lobe grafts. Although current CT criteria produce high specificity and may reduce unnecessary invasive venographies, optimal CT criteria with acceptable sensitivity should be reestablished.

The MR imaging diagnosis of liver diseases using gadoxetic acid: Emphasis on hepatobiliary phase

Hepatocyte specific contrast agents including gadoxetic acid and gadobenate dimeglumine are very useful to diagnose various benign and malignant focal hepatic lesions and even helpful to estimate hepatic functional reservoir. The far delayed phase image referred to as the hepatobiliary phase makes the sensitivity of detection for malignant focal hepatic lesions increased, but specificity of malignant diseases, including hepatocellular carcinoma, metastasis and cholangiocarcinoma, characterization remained to be undetermined.

Right hepatic vein stenosis at anastomosis in patients after living donor liver transplantation: optimal Doppler US venous pulsatility index and CT criteria--receiver operating characteristic analysis.

PURPOSE To establish optimal Doppler ultrasonographic (US) venous pulsatility index and computed tomographic (CT) criteria for right hepatic vein (RHV) stenosis after living donor liver transplantation (LDLT) and to compare accuracies of these methods by using receiver operating characteristic (ROC) analysis. MATERIALS AND METHODS This retrospective study was approved by an institutional review board; informed consent was waived. Eighty patients (48 men, 32 women; mean age, 51.5 years +/- 9.2 [standard deviation]) underwent Doppler US and CT within 8 days of hepatic venography following right lobe LDLT between October 2006 and September 2008. At venography, RHVs were classified into a stenosis or nonstenosis group. At Doppler US, venous pulsatility index was defined as the difference between maximum and minimum frequency shifts divided by maximum frequency shift. At CT, diameters of anastomosis and RHV were measured; percentage of stenosis was calculated. Mean Doppler US and CT parameters in the two groups were compared; ROC analysis was performed. RESULTS There were 30 stenotic and 50 nonstenotic RHVs. Mean venous pulsatility index and mean anastomosis diameter were significantly lower and mean percentage of stenosis was significantly higher in the stenosis than the nonstenosis group (P < .001 each). Optimal cutoffs for venous pulsatility index, anastomosis diameter, and percentage of stenosis were 0.16, 3.7 mm, and 47%, respectively. Sensitivity and specificity were 86.7% and 68.0% for venous pulsatility index, 96.7% and 88.0% for anastomosis diameter, and 96.7% and 86.0% for percentage of stenosis, respectively. At ROC analysis, anastomosis diameter (P = .002) and percentage of stenosis (P = .003) were significantly more accurate than venous pulsatility index. CONCLUSION CT is more accurate than Doppler US for RHV stenosis after LDLT, with venous pulsatility index as the sole sonographic criterion. Patients suspected of having RHV stenosis at Doppler US may benefit from CT to reduce unnecessary venography.

Nonhypervascular Hypointense Nodules at Gadoxetic Acid–enhanced MR Imaging in Chronic Liver Disease: Diffusion-weighted Imaging for Characterization

Hyperintensity at diffusion-weighted imaging could be a useful MR imaging feature to differentiate hypovascular hepatocellular carcinomas from dysplastic nodules seen as hypointense nodules at hepatobiliary phase gadoxetic acid–enhanced MR imaging.