Eun Sil Yu

Non-invasive assessment of hepatic steatosis: Prospective comparison of the accuracy of imaging examinations

BACKGROUND & AIMS Despite increasing use of various imaging examinations for non-invasive assessment of hepatic steatosis (HS), their relative accuracy is unknown. The objective of this study is to prospectively compare the accuracy of computed tomography (CT), dual gradient echo magnetic resonance imaging (DGE-MRI), proton magnetic resonance spectroscopy ((1)H-MRS), and ultrasonography (US) for the diagnosis and quantitative estimation of HS. METHODS A total of 161 consecutive potential living liver donors underwent US (performed by two independent radiologists, US1 and US2), CT, DGE-MRI, (1)H-MRS, and liver biopsy on the same day. Using the histologic degree of HS as the reference standard, we compared the diagnostic performance of US1, US2, CT, DGE-MRI, and (1)H-MRS for diagnosing HS >or= 5% and HS >or= 30% and compared the accuracy of CT, DGE-MRI, and (1)H-MRS in the quantitative estimation of HS. RESULTS DGE-MRI and (1)H-MRS significantly outperformed CT and US for the diagnosis of HS5%. DGE-MRI showed a tendency of higher accuracy than the other examinations for diagnosing HS >or= 30%. The cross-validated sensitivity and specificity of DGE-MRI at the optimal cut-off were 76.7% and 87.1%, respectively, for diagnosing HS >or= 5% and 90.9% and 94%, respectively, for diagnosing HS >or= 30%. The cross-validated Bland-Altman 95% limits of agreement between the estimated degree of HS on imaging examinations and the histologic degree of HS, were the narrowest with DGE-MRI, yielding -12.7% to 12.7%. CONCLUSIONS Among CT, DGE-MRI, (1)H-MRS, and US, DGE-MRI is the most accurate method for the diagnosis and quantitative estimation of HS. Therefore, DGE-MRI may be the preferred imaging examination for the non-invasive assessment of HS.

Visually Isoattenuating Pancreatic Adenocarcinoma at Dynamic-Enhanced CT: Frequency, Clinical and Pathologic Characteristics, and Diagnosis at Imaging Examinations

PURPOSE To retrospectively determine the frequency, clinical and pathologic characteristics, and computed tomographic (CT) findings of visually isoattenuating pancreatic adenocarcinomas and to investigate the utility of magnetic resonance (MR) imaging and positron emission tomography (PET)/CT for detecting them. MATERIALS AND METHODS Institutional review board approval was obtained. Patient informed consent was waived. Of 743 consecutive patients with pathologically proved pancreatic cancer, 644 patients (392 men, 252 women; mean age, 60 years ± 9.5 [standard deviation]) who had undergone both arterial and portal phase contrast material-enhanced CT were included. Visually isoattenuating pancreatic adenocarcinoma was defined as lesion isoattenuation in both scan phases. Serum levels of carbohydrate antigen 19-9, immunoglobulin G (IgG), and IgG fraction 4 (IgG4), survival after curative-intent surgery; and pathologic findings of visually isoattenuating pancreatic adenocarcinomas were analyzed. CT findings of visually isoattenuating pancreatic adenocarcinomas and the sensitivity of MR imaging and PET/CT for detecting them were determined. RESULTS The frequency of visually isoattenuating pancreatic adenocarcinomas among pancreatic cancers was 5.4% (35 of 644). Serum levels of carbohydrate antigen 19-9, IgG, and IgG4 were elevated in 51.5% (17 of 33), 8.3% (one of 12), and 8.3% (one of 12) of patients, respectively. Visually isoattenuating pancreatic adenocarcinoma, compared with usual pancreatic adenocarcinoma, was independently associated with a better survival after curative-intent surgery: Adjusted hazard ratio was 0.430 (P = .006). Thirty surgically resected visually isoattenuating pancreatic adenocarcinomas were 1.5-4 cm (median, 3 cm). Their pathologic findings differed from those of usual pancreatic adenocarcinomas: lower tumor cellularity, more frequent intratumoral acinar tissue and islet cells, and less prominent tumor necrosis. Visually isoattenuating pancreatic adenocarcinomas showed various abnormalities at CT, which may suggest an isoattenuating mass or nodule. Sensitivities of MR imaging and PET/CT were 79.2% (19 of 24) and 73.7% (14 of 19), respectively. CONCLUSION Visually isoattenuating pancreatic adenocarcinoma represents a small but meaningful subset of pancreatic cancer and has characteristic clinical and pathologic features. MR imaging and PET/CT may be useful as subsequent examinations when the patient is suspected of having the lesion at CT.

Hepatic fat quantification: a prospective comparison of magnetic resonance spectroscopy and analysis methods for chemical-shift gradient echo magnetic resonance imaging with histologic assessment as the reference standard.

ObjectiveThe aims of this study were to assess the confounding effects of hepatic iron deposition, inflammation, and fibrosis on hepatic steatosis (HS) evaluation by magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) and to assess the accuracies of MRI and MRS for HS evaluation, using histology as the reference standard. Materials and MethodsIn this institutional review board–approved prospective study, 56 patients gave informed consents and underwent chemical-shift MRI and MRS of the liver on a 1.5-T magnetic resonance scanner. To estimate MRI fat fraction (FF), 4 analysis methods were used (dual-echo, triple-echo, multiecho, and multi-interference), and MRS FF was calculated with T2 correction. Degrees of HS, iron deposition, inflammation, and fibrosis were analyzed in liver resection (n = 37) and biopsy (n = 19) specimens. The confounding effects of histology on fat quantification were assessed by multiple linear regression analysis. Using the histologic degree of HS as the reference standard, the accuracies of each method in estimating HS and diagnosing an HS of 5% or greater were determined by linear regression and receiver operating characteristic analyses. ResultsIron deposition significantly confounded estimations of FF by the dual-echo (P < 0.001) and triple-echo (P = 0.033) methods, whereas no histologic feature confounded the multiecho and multi-interference methods or MRS. The MRS (r = 0.95) showed the strongest correlation with histologic degree of HS, followed by the multiecho (r = 0.92), multi-interference (r = 0.91), triple-echo (r = 0.90), and dual-echo (r = 0.85) methods. For diagnosing HS, the areas under the curve tended to be higher for MRS (0.96) and the multiecho (0.95), multi-interference (0.95), and triple-echo (0.95) methods than for the dual-echo method (0.88) (P ≥ 0.13). ConclusionThe multiecho and multi-interference MRI methods and MRS can accurately quantify hepatic fat, with coexisting histologic abnormalities having no confounding effects.

Results on preemptive or prophylactic treatment of lamivudine in HBsAg (+) renal allograft recipients: comparison with salvage treatment after hepatic dysfunction with HBV recurrence.

Background. Lamivudine has been reported to be able to stabilize liver enzyme and hepatitis B virus (HBV) replication with recurrent hepatitis that has been regarded as a frequent and major risk factor for hepatic dysfunction and chronic liver disease in renal transplant recipients. Because large number of hepatitis antigenemia patients among renal transplant patients experience recurrent hepatic dysfunction with HBV recurrence and permanent histological deterioration, preemptive or primary prophylactic use of lamivudine before transplantation may be more beneficial than a trial for the treatment of advanced hepatic dysfunction. Methods. We conducted a double arm study to compare the efficacy of lamivudine between the preemptive (HBV DNA positive) or prophylactic (HBV DNA negative) trial for the maintenance of stable liver function (n=10) and the trial for the salvage of advanced hepatic dysfunction developed after renal transplantation (n=6) in hepatitis B viremia carrier renal transplant recipients. Results. Hepatic dysfunction with recurrent HBV antigenemia developed in 11 of 36 (30.6%) hepatitis antigenemia patients with a mean duration of 8.4 months (range 5–19.4 months). In six patients treated with lamivudine after hepatic dysfunction from recurrent hepatitis B viremia, serum AST and ALT level normalized within 1 month and HBV-DNA disappeared in all cases. HBV-DNA, however, reappeared in three (50%) without any discontinuation of lamivudine. Liver biopsy revealed recurrent chronic active hepatitis with severe activity of fibrosis in four cases, cholestatic fibrosing hepatitis in one, and permanent cirrhotic change in one. In seven patients who had preemptive lamivudine treatment at 9, 6, 2, 2, 1, 0, 0 month before the transplantation, HBV-DNA had converted to negative with a mean follow up of 1.2 months (range 1–2 month) in all case. Three patients who had prophylactic trials with lamivudine have all remained HBV-DNA negative. The recurrence rate of HBV viremia in the preemptive or prophylactic lamivudine treated group is 10.0% (1/10), which is significantly lower than that (42.3%, 11/25) in the nonlamivudine-treated group. The re-recurrence rate of HBV viremia was significantly higher (3/6, 50.0%) in the reactive lamivudine treated group than in prophylactic or preemptive group (1/10, 10%). Conclusion. Although lamivudine treatment after hepatic dysfunction can be a sound conventional treatment modality, this preliminary study may suggest that preemptive or prophylactic trial of lamivudine before hepatic dysfunction might be a more effective strategy for prevention of permanent histological deterioration and recurrence of hepatitis B viremia.

Peritoneal Mesotheliomas: Clinicopathologic Features, CT Findings, and Differential Diagnosis

OBJECTIVE The objective of our study was to illustrate various CT findings of peritoneal mesotheliomas, to review their clinicopathologic features, and to discuss the differential diagnoses. CONCLUSION The clinicopathologic features of peritoneal mesotheliomas vary among the subtypes such as malignant mesotheliomas, cystic mesotheliomas, and well-differentiated papillary mesotheliomas, and accordingly, there is a spectrum of CT appearances.

Biopsy-proven Nonsteatotic Liver in Adults: Estimation of Reference Range for Difference in Attenuation between the Liver and the Spleen at Nonenhanced CT

PURPOSE To establish the reference range for hepatic attenuation minus splenic attenuation difference (CT(L-S)) values on nonenhanced computed tomographic (CT) images obtained in adults with a biopsy-proved nonsteatotic liver and determine the CT(L-S) criterion for diagnosing hepatic steatosis. MATERIALS AND METHODS This retrospective study was institutional review board approved, and all subjects had provided written informed consent. The CT(L-S) was measured in 315 liver donor candidates (207 men, 108 women; mean age, 31.5 years ± 10.1 [standard deviation]) who underwent nonenhanced CT of the liver and subsequent ultrasonographically guided liver biopsy on the same day. Nonenhanced liver CT was performed with a 16-section multidetector scanner in 154 individuals and with a 64-section multidetector scanner in 161 individuals. Biopsy specimens were analyzed for degree of hepatic steatosis and iron deposition. The CT(L-S) reference range was determined according to Clinical and Laboratory Standards Institute guideline C28-A3 in individuals with a histologically proved nonsteatotic liver. The sensitivity of nonenhanced CT for the diagnosis of 5% or greater and 30% or greater hepatic steatosis with use of the lower limit of the reference range as the diagnostic cutoff was determined. The effects of subject age and sex, CT scanner type, and hepatic iron on the CT(L-S) were evaluated by using multiple linear regression analysis. RESULTS Ninety-six subjects (48 men, 48 women) were found to have a histologically proved nonsteatotic liver, with an estimated reference range for CT(L-S) values of 1-18 HU. With a CT(L-S) of less than 1 HU as the criterion for hepatic steatosis, the sensitivities of nonenhanced CT for 5% or greater and 30% or greater hepatic steatosis were 18.6% (29 of 156 subjects) and 67% (26 of 39 subjects), respectively. Subject age had a significant but negligible effect on CT(L-S) (0.076-HU increase per year of age, P = .009), subject sex and scanner type had no effects on CT(L-S), and hepatic iron deposition significantly increased the CT(L-S) (1.434-HU increase per increase in iron deposition grade, P = .011). CONCLUSION The histologically proved reference range of CT(L-S) values for nonsteatotic livers was 1-18 HU. A CT(L-S) of less than 1 HU could be used as a conservative criterion for diagnosing hepatic steatosis with nonenhanced CT more consistently.

Contrast-enhanced computed tomography for the diagnosis of fatty liver: prospective study with same-day biopsy used as the reference standard

Purpose: The study purpose was to prospectively determine the accuracy of contrast-enhanced CT in diagnosing fatty liver using same-day biopsy as the reference standard. Materials and methods: One hundred seventy-nine potential living liver donors underwent unenhanced and portal-phase contrast-enhanced hepatic CT and subsequent liver biopsy on the same day. Attenuation difference between the liver and the spleen on unenhanced (preL-S) and contrast-enhanced (postL-S) images and blood-subtracted hepatic attenuation on contrast-enhanced images (postL-B), calculated by [L - 0.3 × (0.75 × P + 0.25 × A)]/0.7 where L, P and A represent the attenuation of the liver, main portal vein and abdominal aorta, respectively, were obtained. The accuracy of these indices in diagnosing fatty liver according to various threshold levels, 5%-30% histological steatosis in increments of 5%, was compared using ROC analysis. Results: The area under the ROC curve for preL-S, postL-S and postL-B was 0.663–0.918, 0.712–0.847 and 0.821–0.923, respectively, depending on the threshold levels of hepatic steatosis. The accuracy of preL-S and postL-S did not differ (P ≥ 0.054), despite a trend towards a lower accuracy with postL-S. postL-B yielded higher accuracy than preL-S at threshold levels of 5% and 10% (P ≤ 0.002) and similar accuracy to preL-S at the other threshold levels (P ≥ 0.144). Conclusion: Portal-phase contrast-enhanced CT has a similar, or even greater, accuracy than unenhanced CT in diagnosing fatty liver.

Noninvasive diagnostic criteria for hepatocellular carcinoma in hepatic masses >2 cm in a hepatitis B virus-endemic area.

Background: Noninvasive criteria for diagnosing hepatocellular carcinoma (HCC) suggested by the American Association for the Study of Liver Diseases (AASLD) in 2005 consisted of serum α‐fetoprotein (AFP) level >200 ng/ml or a typical enhancement pattern (arterial enhancement and portal/delayed washed out) on dynamic imaging of hepatic mass(es) >2 cm in a cirrhotic liver.

Focal nodular hyperplasia or focal nodular hyperplasia‐like lesions of the liver: A special emphasis on diagnosis

Background and Aim:  Focal nodular hyperplasia (FNH) and FNH‐like lesions are hypervascular masses that can mimic hepatocellular carcinoma (HCC). We have investigated the clinical, radiological and pathological features of FNH and FNH‐like lesions of the liver, with particular focus on the aspect of diagnosis.

Intravoxel incoherent motion MRI for liver fibrosis assessment: a pilot study.

Background There has been a growing need for an imaging method for the accurate diagnosis and staging of liver fibrosis as a non-invasive alternative to liver biopsy. Purpose To evaluate the feasibility of intra-voxel incoherent motion (IVIM) imaging for classifying the severity of liver fibrosis. Material and Methods Fifty-seven patients who underwent navigator-triggered, diffusion-weighted imaging (DWI) of the liver on a 1.5-T system using nine b-values and had a reliable reference standard for the diagnosis of liver fibrosis (histopathologic findings [n = 27] or clinical findings for normal [n = 18] or cirrhotic liver [n = 12]), were included in our study. Liver apparent diffusion coefficient (ADC), pure diffusion (Dslow), perfusion fraction (f), and perfusion-related diffusion (Dfast), and the product f · Dfast were compared with the liver fibrosis stages (F). The accuracies of these parameters in diagnosing severe liver fibrosis (F ≥3) were evaluated using the receiver-operating characteristic (ROC) curve analysis. Results The liver fibrosis stages had the strongest negative correlation with f · Dfast (ρ = –0.52). All of the parameters, except for Dslow, were significantly lower in patients with F ≥3 than in those with F ≤2 (P ≤ 0.001). The area under the ROC curve for diagnosing severe fibrosis was the largest for f · Dfast (0.844) with an overall accuracy of 79.0% (45/57) at the optimal cutoff value and followed by f (0.834), Dfast (0.773), ADC (0.762), and Dslow (0.656). Conclusion IVIM imaging is a promising method for classifying the severity of liver fibrosis, with the product f · Dfast being the most accurate parameter.