Eun Sun Lee

Hepatic Fibrosis: Prospective Comparison of MR Elastography and US Shear-Wave Elastography for Evaluation

PURPOSE To compare magnetic resonance (MR) elastography and ultrasonographic shear-wave elastography ( SWE shear-wave elastography ) for the staging of hepatic fibrosis ( HF hepatic fibrosis ) in the same individuals. MATERIALS AND METHODS This prospective study was approved by the institutional review board, and informed consent was obtained from all patients. The technical success of and reliable liver stiffness ( LS liver stiffness ) measurement rates at MR elastography and SWE shear-wave elastography were compared in 129 patients who underwent both examinations. For mutual validation, LS liver stiffness values measured at both examinations were correlated by using Pearson correlation. The diagnostic performance of the two techniques for the assessment of substantial HF hepatic fibrosis (stage ≥ F2) was compared by using nonparametric receiver operating characteristic analysis. RESULTS The technical success rates of MR elastography and SWE shear-wave elastography were 95.35% (123 of 129) and 97.67% (126 of 129), respectively (P = .51). MR elastography provided significantly more reliable LS liver stiffness measurements than did SWE shear-wave elastography (95.35% [123 of 129] vs 75.2% [97 of 129], P < .001). The two examinations showed moderate correlation (r = 0.724). In patients with HF hepatic fibrosis stages of F3 or lower, the two examinations showed moderate-to-strong correlation (r = 0.683 in normal livers, 0.754 in livers with stage F0 or F1 HF hepatic fibrosis , and 0.90 in livers with stage F2 or F3 HF hepatic fibrosis ; P < .001); however, they did not show significant correlation for stage F4 HF hepatic fibrosis (r = 0.30, P = .31). MR elastography and SWE shear-wave elastography showed similar diagnostic capability in depicting HF hepatic fibrosis of stage F2 or greater (P = .98) when LS liver stiffness measurements were reliably performed. CONCLUSION MR elastography and SWE shear-wave elastography showed moderate correlation and similar diagnostic performance in the diagnosis of HF hepatic fibrosis of stage F2 or greater; however, MR elastography yielded more reliable LS liver stiffness measurements than did SWE shear-wave elastography .

MR elastography for noninvasive assessment of hepatic fibrosis: reproducibility of the examination and reproducibility and repeatability of the liver stiffness value measurement.

To determine the reproducibility of MR elastography (MRE) and the reproducibility and repeatability of the stiffness measurement of MRE in the staging of liver fibrosis.

The Role of Perfusion CT as a Follow-up Modality After Transcatheter Arterial Chemoembolization An Experimental Study in a Rabbit Model

Objectives:To prospectively evaluate the feasibility of perfusion CT as a follow-up modality after transcatheter arterial chemoembolization (TACE) and to compare these findings with those of histopathology as the reference standard in a VX2 tumor rabbit model. Materials and Methods:VX2 carcinoma tumors were implanted into the liver of 20 rabbits 3 weeks prior to TACE. Perfusion CT was performed prior to TACE and 1- and 4-week after TACE. After obtaining perfusion index maps on perfusion CT, 2 radiologists measured the parametric perfusion indices of blood flow (BF), blood volume (BV), mean transit time (MTT), permeability of the capillary vessel surface (PS), and hepatic arterial fraction (HAF) of primary tumors on pre-TACE perfusion CT, chemoembolized primary tumors on 1-week perfusion CT, and recurred tumors on 4-week perfusion CT. The normal liver parenchyma indices were also recorded. In addition, the radiologists investigated the presence of a recurred tumor adjacent to the chemoembolized area on perfusion index maps of 4-week CT images. The areas of higher hepatic blood flow (HBF), hepatic blood volume (HBV), PS, and HAF, and lower MTT on 4-week perfusion CT than the normal liver parenchyma and the identical area on 1-week perfusion CT were considered as recurred tumors. Histopathology revealed the presence of a recurred tumor, and mean vessel density (MVD) was determined by immunochemical staining for CD31. CT perfusion indices were compared by use of the t test. Comparisons were made for the primary tumor versus normal liver parenchyma on pre-TACE CT, the primary tumor on pre-TACE CT versus the chemoembolized tumor on 1-week CT, the recurred tumor on 4-week CT versus the identical area on 1-week CT, and the primary tumor on pre-TACE CT versus the recurred tumor on 4-week CT. For the detection of recurred tumors, the sensitivity and specificity for 4-week perfusion CT were calculated. Correlation analysis between the recurred tumor perfusion indices and the MVD of the corresponding tumor region was performed. Among 20 rabbits, 6 were excluded from the analysis, and results were based on 14 rabbits. Results:Recurred tumors were histologically proven in 8 of 14 rabbits (57.1%). The BF, BV, PS, and HAF indices of primary tumors were significantly higher, whereas the MTT was significantly lower than that of the normal liver parenchyma on pre-TACE perfusion CT and that of chemoembolized areas on 1-week perfusion CT (P < 0.05). In addition, recurred tumors also showed significantly higher BF, BV, PS, and HAF, and lower MTT indices than the identical areas on 1-week perfusion CT (P < 0.05). The perfusion indices of recurred tumors were not significantly different from the indices of primary tumors (P > 0.05). Both sensitivity and specificity were 100% for 4-week perfusion CT. There were significant positive correlations between BF (r = 0.947), BV (r = 0.758), PS (r = 0.759), HAF (r = 0.955), and MVD in recurred tumors, and a significant inverse correlation between MTT (r = −0.782) and MVD was observed (P < 0.05). Conclusions:We believe that perfusion CT is a feasible alternative modality for the successful early response assessment and early detection of a marginally recurred tumor after TACE. However, perfusion CT has limitations for the prediction of tumor recurrence after TACE.

Staging of hepatic fibrosis: comparison of magnetic resonance elastography and shear wave elastography in the same individuals.

Objective To cross-validate liver stiffness (LS) measured on shear wave elastography (SWE) and on magnetic resonance elastography (MRE) in the same individuals. Materials and Methods We included 94 liver transplantation (LT) recipients and 114 liver donors who underwent either MRE or SWE before surgery or biopsy. We determined the technical success rates and the incidence of unreliable LS measurements (LSM) of SWE and MRE. Among the 69 patients who underwent both MRE and SWE, the median and coefficient of variation (CV) of the LSM from each examination were compared and correlated. Areas under the receiver operating characteristic curve in both examinations were calculated in order to exclude the presence of hepatic fibrosis (HF). Results The technical success rates of MRE and SWE were 96.4% and 92.2%, respectively (p = 0.17), and all of the technical failures occurred in LT recipients. SWE showed 13.1% unreliable LSM, whereas MRE showed no such case (p < 0.05). There was moderate correlation in the LSM in both examinations (r = 0.67). SWE showed a significantly larger median LSM and CV than MRE. Both examinations showed similar diagnostic performance for excluding HF (Az; 0.989, 1.000, respectively). Conclusion MRE and SWE show moderate correlation in their LSMs, although SWE shows higher incidence of unreliable LSMs in cirrhotic liver.

Adaptive statistical iterative reconstruction and Veo: assessment of image quality and diagnostic performance in CT colonography at various radiation doses.

Objectives To evaluate the diagnostic performance of computed tomography (CT) colonography (CTC) reconstructed with different levels of adaptive statistical iterative reconstruction (ASiR, GE Healthcare) and Veo (model-based iterative reconstruction, GE Healthcare) at various tube currents in detection of polyps in porcine colon phantoms. Methods Five porcine colon phantoms with 46 simulated polyps were scanned at different radiation doses (10, 30, and 50 mA s) and were reconstructed using filtered back projection (FBP), ASiR (20%, 40%, and 60%) and Veo. Eleven data sets for each phantom (10-mA s FBP, 10-mA s 20% ASiR, 10-mA s 40% ASiR, 10-mA s 60% ASiR, 10-mA s Veo, 30-mA s FBP, 30-mA s 20% ASiR, 30-mA s 40% ASiR, 30-mA s 60% ASiR, 30-mA s Veo, and 50-mA s FBP) yielded a total of 55 data sets. Polyp detection sensitivity and confidence level of 2 independent observers were evaluated with the McNemar test, the Fisher exact test, and receiver operating characteristic curve analysis. Comparative analyses of overall image quality score, measured image noise, and interpretation time were also performed. Results Per-polyp detection sensitivities and specificities were highest in 10-mA s Veo, 30-mA s FBP, 30-mA s 60% ASiR, and 50-mA s FBP (sensitivity, 100%; specificity, 100%). The area-under-the-curve values for the overall performance of each data set was also highest (1.000) at 50-mA s FBP, 30-mA s FBP, 30-mA s 60% ASiR, and 10-mA s Veo. Images reconstructed with ASiR showed statistically significant improvement in per-polyp detection sensitivity as the percent level of per-polyp sensitivity increased (10-mA s FBP vs 10-mA s 20% ASiR, P = 0.011; 10-mA s FBP vs 10-mA s 40% ASiR, P = 0.000; 10-mA s FBP vs 10-mA s 60% ASiR, P = 0.000; 10-mA s 20% ASiR vs 40% ASiR, P = 0.034). Overall image quality score was highest at 30-mA s Veo and 50-mA s FBP. The quantitative measurement of the image noise was lowest at 30-mA s Veo and second lowest at 10-mA s Veo. There was a trend of decrease in time required for image interpretation as the percent level of ASiR increased, and ASiR or Veo was used instead of FBP. However, differences from comparative analyses of overall image quality score, measured image noise, and interpretation time did not reach statistical significance. Conclusion ASiR and Veo showed improved diagnostic performance with excellent sensitivity and specificity with less image noise and good image quality compared with FBP reconstruction of same radiation dose. Our study confirmed feasibility of low-dose CTC with iterative reconstruction as a promising screening tool with excellent diagnostic performance similar to that of the standard-dose CTC with FBP.

Synergistic effect of ERK inhibition on tetrandrine-induced apoptosis in A549 human lung carcinoma cells

Tetrandrine (TET), a bis-benzylisoquinoline alkaloid from the root of Stephania tetrandra, is known to have anti-tumor activity in various malignant neoplasms. However, the precise mechanism by which TET inhibits tumor cell growth remains to be elucidated. The present studies were performed to characterize the potential effects of TET on phosphoinositide 3-kinase/Akt and extracellular signal-regulated kinase (ERK) pathways since these signaling pathways are known to be responsible for cell growth and survival. TET suppressed cell proliferation and induced apoptosis in A549 human lung carcinoma cells. TET treatment resulted in a down-regulation of Akt and ERK phosphorylation in both time-/concentration-dependent manners. The inhibition of ERK using PD98059 synergistically enhanced the TET-induced apoptosis of A549 cells whereas the inhibition of Akt using LY294002 had a less significant effect. Taken together, our results suggest that TET: i) selectively inhibits the proliferation of lung cancer cells by blocking Akt activation and ii) increases apoptosis by inhibiting ERK. The treatment of lung cancers with TET may enhance the efficacy of chemotherapy and radiotherapy and increase the apoptotic potential of lung cancer cells.

Differentiating between adenomyomatosis and gallbladder cancer: revisiting a comparative study of high-resolution ultrasound, multidetector CT, and MR imaging.

Objective To compare the diagnostic performance of high-resolution ultrasound (HRUS) with contrast-enhanced CT and contrast-enhanced magnetic resonance imaging (MRI) with MR cholangiopancreatography (MRCP) to differentiate between adenomyomatosis (ADM) and gallbladder cancer (GBCA). Materials and Methods Forty patients with surgically proven ADM (n = 13) or GBCA at stage T2 or lower (n = 27) who previously underwent preoperative HRUS, contrast-enhanced CT, and contrast-enhanced MRI with MRCP were retrospectively included in this study. According to the well-known diagnostic criteria, two reviewers independently analyzed the images from each modality separately with a five-point confidence scale. The interobserver agreement was calculated using weighted κ statistics. A receiver operating characteristic curve analysis was performed and the sensitivity, specificity, and accuracy were calculated for each modality when scores of 1 or 2 indicated ADM. Results The interobserver agreement between the two reviewers was good to excellent. The mean Az values for HRUS, multidetector CT (MDCT), and MRI were 0.959, 0.898, and 0.935, respectively, without any statistically significant differences between any of the modalities (p > 0.05). The mean sensitivity of MRI with MRCP (80.8%) was significantly higher than that of MDCT (50.0%) (p = 0.0215). However, the mean sensitivity of MRI with MRCP (80.8%) was not significantly different from that of HRUS (73.1%) (p > 0.05). The mean specificities and accuracies among the three modalities were not significantly different (p > 0.05). Conclusion High-resolution ultrasound and MRI with MRCP have comparable sensitivity and accuracy and MDCT has the lowest sensitivity and accuracy for the differentiation of ADM and GBCA.

Intraductal papillary mucinous neoplasms of the pancreas: evaluation of malignant potential and surgical resectability by using MR imaging with MR cholangiography.

PURPOSE To evaluate the diagnostic performance of magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP) in determining the malignant potential and surgical resectability of pancreas intraductal papillary mucinous neoplasms (IPMNs). MATERIALS AND METHODS Institutional review board approval was obtained, and the requirement for informed consent was waived. Ninety-eight patients with pathologically proved pancreas IPMNs who underwent MR imaging with MRCP comprised the study population. MR images were analyzed for findings suggestive of high-risk stigmata or worrisome features, as proposed by the international consensus guidelines 2012. Interobserver agreement between two experienced observers (observers 1 and 2) and one inexperienced observer (observer 3) was assessed. Diagnostic performance of MR imaging in the evaluation of the malignant potential and surgical resectability of IPMNs was analyzed in these three observers by using receiver operating curve analysis. RESULTS MR imaging with MRCP showed sensitivity of 83% (35/42), 79% (33/42), and 90% (38/42); specificity of 80% (41/51), 51% (26/51), and 24% (12/51); and accuracy of 82% (76/93), 63% (59/93), and 54% (50/93) for observers 1, 2, and 3, respectively, in the evaluation of the malignant potential of pancreas IPMNs when at least one worrisome feature was present. Interobserver agreement in the detection of intramural nodules (κ = 0.349-0.574), enhanced solid components (κ = 0.318-0.574), and measurement of main pancreatic duct diameter (intraclass correlation coefficient = 0.9477) was fair to high. The respective sensitivity, specificity, and accuracy in determination of surgical resectability were 95% (81/85), 99% (84/85), and 88% (75/85); 69% (9/13), 69% (9/13), and 54% (7/13); and 92% (90/98), 95% (93/98), and 84% (82/98) for observers 1, 2, and 3. CONCLUSION MR imaging with MRCP is a useful modality in the evaluation of the malignant potential and resectability of IPMNs, with high sensitivity and moderate specificity in the experienced radiologists but relatively low specificity in the inexperienced radiology trainee.

High Spatial Resolution, Respiratory-gated, T1-weighted Magnetic Resonance Imaging of the Liver and the Biliary Tract During the Hepatobiliary Phase of Gadoxetic Acid–enhanced Magnetic Resonance Imaging

Purpose The aim of this study was to demonstrate the clinical feasibility of a recently developed navigator-gated, 3-dimensional gradient echo (3D-GRE) sequence for high-resolution, T1-weighted imaging (HR-T1WI) during the hepatobiliary phase (HBP) of gadoxetic acid–enhanced liver magnetic resonance imaging (MRI). Materials and Methods Eighty-seven consecutive patients who underwent gadoxetic acid–enhanced liver MRI were included in this study. To obtain HR-T1WI (acquired resolution, 1 × 1 × 2 mm), a gated 3D-GRE sequence (gated volumetric interpolated breath-hold examination [VIBE]; Siemens) with fat suppression was performed during the HBP and was then compared with standard breath-hold (BH)–GRE sequence (BH-VIBE). For the respiration gating, the phase ordering using the automatic window selection technique was used. Three readers independently scored the artifacts and the imaging quality (IQ) of both image sets and also classified BH-VIBE images into acceptable or unacceptable IQ. Noise and signal-noise ratio of the BH-VIBE and gated-VIBE sequences were compared, and image quality improvement using gated VIBE compared with BH-VIBE was determined when BH-VIBE shows unacceptable IQ. Results The gated-VIBE sequence successfully provided HR-T1WI, having diagnosable image quality in all patients except 4 patients in 1 reader (95.4%, 83/87). The gated-VIBE sequence showed relatively higher levels of noise (mean [SD], 6.04 [3.18] vs 3.57 [0.66]) but similar signal-noise ratio (93.60 [39.47] vs 100.05 [28.94]) compared with BH-VIBE (P = 0.15). In the qualitative analysis, the gated 3D-GRE sequence showed higher scores for depicting focal liver lesions and the sharpness of the hepatic edges (P < 0.0001) but lower subjective overall IQ than did the BH-VIBE (P < 0.01). However, in the patients showing unacceptable BH-VIBE image quality, the degree of improvement of the IQ using the gated-VIBE technique was significantly higher than that seen in the patients showing acceptable BH-VIBE image quality (P < 0.01). Conclusions T1-weighted gated-VIBE showed technical feasibility for HR-T1WI during HBP imaging of gadoxetic acid–enhanced MRI.

Computed tomography features of extensively drug-resistant pulmonary tuberculosis in non-HIV-infected patients.

Objective: To describe the computed tomography (CT) findings of pulmonary extensively drug-resistant tuberculosis (XDR-TB) in non-HIV-infected patients and to compare them with those of non-XDR multidrug-resistant tuberculosis (MDR-TB). Methods: Retrospective review of microbiological results and drug-susceptibility tests of 260 non-HIV-infected patients who had been diagnosed with pulmonary MDR-TB from 1994 to 2005 revealed that 47 patients had XDR-TB, whereas the other 213 patients had non-XDR MDR-TB. Twenty of the 47 XDR-TB patients and 85 of the 213 non-XDR MDR-TB patients with available CT examinations were included in this study. Two radiologists reviewed the CT studies in consensus for the presence and extent of micronodules, tree-in-bud appearance, lobular consolidation (<2 cm), consolidation, cavity, bronchiectasis, emphysema, pleural effusion, lymphadenopathy, bronchopleural fistula, and empyema. We then compared the CT features of XDR-TB with those of non-XDR MDR-TB. Results: Micronodules and tree-in-bud appearance were the most frequent CT abnormalities and were seen in all XDR-TB patients (100%). Consolidations, cavities, bronchiectasis, and lobular consolidations were found in 85%, 85%, 80%, and 70% of XDR-TB patients, respectively. The extents of micronodules, tree-in-bud appearance, lobular consolidation, consolidation, cavity, bronchiectasis, and emphysema were 3.60, 3.55, 1.35, 1.85, 1.65, 1.45, and 0.25 lobes, respectively. Compared with non-XDR MDR-TB, XDR-TB showed a significantly larger extent of tree-in-bud appearance and consolidation (P < 0.05). With respect to other CT features, there were no significant differences between XDR-TB and non-XDR MDR-TB. Conclusion: Computed tomography findings of pulmonary XDR-TB are similar to those of non-XDR MDR-TB; however, XDR-TB tends to have more extensive consolidation and tree-in-bud appearance.