Tomoko Hyodo

Hypovascular nodules in patients with chronic liver disease: risk factors for development of hypervascular hepatocellular carcinoma.

PURPOSE To identify patient characteristics and magnetic resonance (MR) imaging findings associated with subsequent hypervascularization in hypovascular nodules that show hypointensity on hepatobiliary phase gadoxetic acid-enhanced MR images in patients with chronic liver diseases. MATERIALS AND METHODS Institutional review board approval was obtained, and informed consent was waived. At multiple follow-up gadoxetic acid-enhanced MR imaging examinations of 68 patients, 160 hypovascular nodules were retrospectively reviewed. A Cox regression model for hypervascularization was developed to explore the association of baseline characteristics, including patient factors (Child-Pugh classification, etiology of liver disease, history of local therapy for hepatocellular carcinoma [HCC], and coexistence of hypervascular HCC) and MR imaging findings (fat content, signal intensity on T2-weighted images, and nodule size). In addition, the growth rate was calculated as the reciprocal of tumor volume doubling time to investigate its relationship with subsequent hypervascularization by using receiver operating characteristic and Kaplan-Meier analyses. RESULTS The prevalence of subsequent hypervascularization was 31% (50 of 160 nodules). Independent Cox multivariable predictors of increased risk of hypervascularization were hyperintensity on T2-weighted images (hazard ratio [HR] = 8.7; 95% confidence interval [CI]: 3.6, 20.8), previous local therapy for hypervascular HCC (HR = 5.0; 95% CI: 1.8, 13.6), Child-Pugh B cirrhosis (HR = 3.6; 95% CI: 1.4, 9.5) and coexistence of hypervascular HCC (HR = 2.0; 95% CI: 1.0, 3.8). The mean growth rate was significantly higher in nodules that showed subsequent hypervascularization than in those without hypervascularization. Kaplan-Meier analysis based on the receiver operating characteristic cutoff level (1.8 × 10(-3)/day [tumor volume doubling time, 542 days]) showed that nodules with a higher growth rate had a significantly higher incidence of hypervascularization (P = 5.2 × 10(-8), log-rank test). CONCLUSION Hyperintensity on T2-weighted images is an independent and strong risk factor at baseline for subsequent hypervascularization in hypovascular nodules in patients with chronic liver disease. Tumor volume doubling time of less than 542 days was associated with a high rate of subsequent hypervascularization.

Value of EUS in early detection of pancreatic ductal adenocarcinomas in patients with intraductal papillary mucinous neoplasms.

BACKGROUND AND STUDY AIMS Pancreatic ductal adenocarcinomas (PDAC) sometimes arise in patients with intraductal papillary mucinous neoplasms (IPMNs). This study examined the incidence of PDACs concomitant to or derived from branch duct IPMNs. The usefulness of endoscopic ultrasonography (EUS) relative to other imaging methods for detecting these tumors was also assessed. PATIENTS AND METHODS This retrospective study used data from clinical records and imaging studies that were collected prospectively. During 2001-2009, 167 consecutive patients with IPMNs underwent EUS, ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The 102 patients whose branch duct IPMNs lacked mural nodules/symptoms and thus did not qualify for resection were followed up by semiannual EUS and annual ultrasonography, CT, and MRI. The sensitivity and specificity with which the four modalities detected IPMN-derived and -concomitant PDACs at the first examination and throughout the study period were evaluated. The rate of PDAC development during follow-up was analyzed by the Kaplan-Meier method. RESULTS A total of 17 IPMN-derived and 11 IPMN-concomitant PDACs were diagnosed at the first examination. Lesions that did not qualify for resection or chemotherapy were followed up for a median of 42 months. Seven IPMN-concomitant PDACs and no IPMN-derived PDACs were detected during follow-up. The 3- and 5-year rates of IPMN-concomitant PDAC development were 4.0% and 8.8%, respectively. At the first examination, EUS was superior to other imaging modalities in terms of IPMN-derived and -concomitant PDAC detection. Throughout the study period, including follow-up, EUS was significantly better at detecting IPMN-concomitant PDACs than the other modalities. CONCLUSIONS IPMN-concomitant PDACs are quite often found at diagnosis and during follow-up. EUS examination of the whole pancreas plays an important role in the management of IPMNs as it allows the early detection of these small invasive carcinomas.

CT and MR cholangiography: advantages and pitfalls in perioperative evaluation of biliary tree

Recent developments in imaging technology have enabled CT and MR cholangiopancreatography (MRCP) to provide minimally invasive alternatives to endoscopic retrograde cholangiopancreatography for the pre- and post-operative assessment of biliary disease. This article describes anatomical variants of the biliary tree with surgical significance, followed by comparison of CT and MR cholangiographies. Drip infusion cholangiography with CT (DIC-CT) enables high-resolution three-dimensional anatomical representation of very small bile ducts (e.g. aberrant branches, the caudate branch and the cystic duct), which are potential causes of surgical complications. The disadvantages of DIC-CT include the possibility of adverse reactions to biliary contrast media and insufficient depiction of bile ducts caused by liver dysfunction or obstructive jaundice. Conventional MRCP is a standard, non-invasive method for evaluating the biliary tree. MRCP provides useful information, especially regarding the extrahepatic bile ducts and dilated intrahepatic bile ducts. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRCP may facilitate the evaluation of biliary structure and excretory function. Understanding the characteristics of each type of cholangiography is important to ensure sufficient perioperative evaluation of the biliary system.

Ultrasonography, Computed Tomography and Magnetic Resonance Imaging of Hepatocellular Carcinoma: Toward Improved Treatment Decisions

Detection, characterization, staging, and treatment monitoring are major roles in imaging diagnosis in liver cancers. Contrast-enhanced ultrasonography (CEUS) using microbubble contrast agents has expanded the role of US in the detection and diagnosis of liver nodules in patients at high risk of hepatocellular carcinoma (HCC). CEUS provides an accurate differentiation between benign and malignant liver nodules, which is critical for adequate management of HCC and is also useful for guidance of percutaneous local therapy of HCC and postprocedure monitoring of the therapeutic response. The technology of multidetector-row computed tomography (MDCT) has increased spatial and temporal resolutions of computed tomography (CT). It has made possible a more precise evaluation of the hemodynamics of liver tumor, and the diagnostic accuracy of dynamic MDCT has improved. Perfusion CT can measure tissue perfusion parameters quantitatively and can assess segmental hepatic function. Dynamic MDCT with high spatial and temporal resolution enables us to reconstruct 3- and 4-dimensional imaging, which is very useful for pretreatment evaluation. Dual-energy CT makes possible the differentiation of materials and tissues in images obtained based on the differences in iodine and water densities. Monochromatic images, which can be reconstructed by dual-energy CT data, provide some improvement in contrast and show a higher contrast-to-noise ratio for hypervascular HCCs. Dynamic magnetic resonance imaging with fast imaging sequence of 3-dimensional Fourier transformation T1-weighted gradient echo and nonspecific contrast medium can show high detection sensitivity of hypervascular HCC. However, the hepatic tissue-specific contrast medium, gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid, has become an essential contrast medium for liver imaging because of its higher diagnostic ability. It may replace CT during hepatic arteriography and during arterioportography.

Hypovascular Hepatic Nodules Showing Hypointense on the Hepatobiliary-Phase Image of Gd-EOB-DTPA-Enhanced MRI to Develop a Hypervascular Hepatocellular Carcinoma: A Nationwide Retrospective Study on Their Natural Course and Risk Factors

Objective: We aimed to investigate the natural outcome of nonhypervascular lesions detected in the hepatobiliary phase of gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI by performing a longitudinal study retrospectively enrolled in a nationwide manner. Methods: Between February 2008 and March 2011, 224 patients with 504 nodules that were diagnosed as nonhypervascular by imaging were recruited from institutions that participated in the present study. We examined the natural outcome of nonhypervascular lesions and evaluated the risk factors. Results: Of the 504 nodules, 173 (34.3%) showed hypervascular transformation. The overall cumulative incidence of hypervascular transformation was 14.9% at 12 months and 45.8% at 24 months. Multivariate analysis using the Cox regression model revealed previous treatment history for hepatocellular carcinoma (HCC; relative risk = 1.498; p = 0.036, 95% CI 1.03-2.19) and hyperintensity on T2-weighted images (relative risk = 1.724; p = 0.015, 95% CI 1.11-2.67) were identified as independent factors for hypervascular transformation. Conclusions: Patients who have a previous treatment history for HCC and with hypointense nodules showing hyperintensity on T2-weighted images need careful follow-up because of the high incidence of hypervascular transformation.

Usefulness of Combination of Imaging Modalities in the Diagnosis of Hepatocellular Carcinoma Using Sonazoid®-Enhanced Ultrasound, Gadolinium Diethylene-Triamine-Pentaacetic Acid-Enhanced Magnetic Resonance Imaging, and Contrast-Enhanced Computed Tomography

Objective: To clarify the diagnostic ability of combining imaging methods to diagnose hepatocellular carcinoma (HCC) using Sonazoid®-enhanced ultrasound (US), gadolinium diethylene-triamine-pentaacetic acid-enhanced (Gd-EOB-DTPA) magnetic resonance imaging (MRI), and contrast-enhanced computed tomography (CECT). Methods: A total of 32 patients who underwent surgical resection for HCC were studied. Sonazoid-enhanced US, Gd-EOB-DTPA MRI, CECT, and intraoperative contrast-enhanced ultrasonography were done for all patients. The definitive diagnosis of HCC in those patients was based on histopathological confirmation. Results: A total of 50 histologically proven HCCs were obtained from 32 patients; their mean (±SD) age was 68.3 years ± 8.1. The mean (±SD) nodule size was 2.6 cm ± 1.9. Twenty percent were well-differentiated HCC, 64% were moderately differentiated HCC, 10% were poorly differentiated HCC, 4% were combined HCC and CCC, and 2% were HCC with severe necrosis. The overall diagnostic sensitivity of CEUS, CECT, and Gd-EOB-DTPA MRI was 72, 74, and 86%, respectively; however, there was no significant difference between the three imaging modalities in diagnosing typical HCC (p = 0.092). When combining the diagnostic ability of the different imaging modalities, the diagnostic sensitivity of Sonazoid-enhanced US and Gd-EOB-DTPA MRI was 90%, while addition of Sonazoid-enhanced US to CECT and CECT to Gd-EOB-DTPA MRI had a sensitivity of 82 and 88%, respectively. There was no significant difference between the three imaging combinations (p = 0.970). Conclusion: Sonazoid-enhanced US and Gd-EOB-DTPA MRI can be confidently used in daily clinical practice for the management of HCC.

Clinical application of 3D arterial spin-labeled brain perfusion imaging for Alzheimer disease: comparison with brain perfusion SPECT.

BACKGROUND AND PURPOSE: Alzheimer disease is the most common neurodegenerative disorder with dementia, and a practical and economic biomarker for diagnosis of Alzheimer disease is needed. Three-dimensional arterial spin-labeling, with its high signal-to-noise ratio, enables measurement of cerebral blood flow precisely without any extrinsic tracers. We evaluated the performance of 3D arterial spin-labeling compared with SPECT, and demonstrated the 3D arterial spin-labeled imaging characteristics in the diagnosis of Alzheimer disease. MATERIALS AND METHODS: This study included 68 patients with clinically suspected Alzheimer disease who underwent both 3D arterial spin-labeling and SPECT imaging. Two readers independently assessed both images. Kendall W coefficients of concordance (K) were computed, and receiver operating characteristic analyses were performed for each reader. The differences between the images in regional perfusion distribution were evaluated by means of statistical parametric mapping, and the incidence of hypoperfusion of the cerebral watershed area, referred to as “borderzone sign” in the 3D arterial spin-labeled images, was determined. RESULTS: Readers showed K = 0.82/0.73 for SPECT/3D arterial spin-labeled imaging, and the respective areas under the receiver operating characteristic curve were 0.82/0.69 for reader 1 and 0.80/0.69 for reader 2. Statistical parametric mapping showed that the perisylvian and medial parieto-occipital perfusion in the arterial spin-labeled images was significantly higher than that in the SPECT images. Borderzone sign was observed on 3D arterial spin-labeling in 70% of patients misdiagnosed with Alzheimer disease. CONCLUSIONS: The diagnostic performance of 3D arterial spin-labeling and SPECT for Alzheimer disease was almost equivalent. Three-dimensional arterial spin-labeled imaging was more influenced by hemodynamic factors than was SPECT imaging.

Can low-dose CT with iterative reconstruction reduce both the radiation dose and the amount of iodine contrast medium in a dynamic CT study of the liver?

PURPOSE To investigate whether low-dose dynamic CT of the liver with iterative reconstruction can reduce both the radiation dose and the amount of contrast medium. MATERIALS AND METHODS This study was approved by our institutional review board. 113 patients were randomly assigned to one of two groups. Group A/group B (fifty-eight/fifty-five patients) underwent liver dynamic CT at 120/100 kV, with 0/40% adaptive statistical iterative reconstruction (ASIR), with a contrast dose of 600/480 mg I/kg, respectively. Radiation exposure was estimated based on the manufacturers phantom data. The enhancement value of the hepatic parenchyma, vessels and the tumor-to-liver contrast of hepatocellular carcinomas (HCCs) were compared between two groups. Two readers independently assessed the CT images of the hepatic parenchyma and HCCs. RESULTS The mean CT dose indices: 6.38/4.04 mGy, the dose-length products: 194.54/124.57 mGy cm, for group A/group B. The mean enhancement value of the hepatic parenchyma and the tumor-to-liver contrast of HCCs with diameters greater than 1cm in the post-contrast all phases did not differ significantly between two groups (P>0.05). The enhancement values of vessels in group B were significantly higher than that in group A in the delayed phases (P<0.05). Two readers confidence levels for the hepatic parenchyma in the delayed phases and HCCs did not differ significantly between the groups (P>0.05). CONCLUSIONS Low-dose dynamic CT with ASIR can reduce both the radiation dose and the amount of contrast medium without image quality degradation, compared to conventional dynamic CT without ASIR.

Multimaterial Decomposition Algorithm for the Quantification of Liver Fat Content by Using Fast-Kilovolt-Peak Switching Dual-Energy CT: Experimental Validation.

Purpose To assess the ability of fast-kilovolt-peak switching dual-energy computed tomography (CT) by using the multimaterial decomposition (MMD) algorithm to quantify liver fat. Materials and Methods Fifteen syringes that contained various proportions of swine liver obtained from an abattoir, lard in food products, and iron (saccharated ferric oxide) were prepared. Approval of this study by the animal care and use committee was not required. Solid cylindrical phantoms that consisted of a polyurethane epoxy resin 20 and 30 cm in diameter that held the syringes were scanned with dual- and single-energy 64-section multidetector CT. CT attenuation on single-energy CT images (in Hounsfield units) and MMD-derived fat volume fraction (FVF; dual-energy CT FVF) were obtained for each syringe, as were magnetic resonance (MR) spectroscopy measurements by using a 1.5-T imager (fat fraction [FF] of MR spectroscopy). Reference values of FVF (FVFref) were determined by using the Soxhlet method. Iron concentrations were determined by inductively coupled plasma optical emission spectroscopy and divided into three ranges (0 mg per 100 g, 48.1-55.9 mg per 100 g, and 92.6-103.0 mg per 100 g). Statistical analysis included Spearman rank correlation and analysis of covariance. Results Both dual-energy CT FVF (ρ = 0.97; P < .001) and CT attenuation on single-energy CT images (ρ = -0.97; P < .001) correlated significantly with FVFref for phantoms without iron. Phantom size had a significant effect on dual-energy CT FVF after controlling for FVFref (P < .001). The regression slopes for CT attenuation on single-energy CT images in 20- and 30-cm-diameter phantoms differed significantly (P = .015). In sections with higher iron concentrations, the linear coefficients of dual-energy CT FVF decreased and those of MR spectroscopy FF increased (P < .001). Conclusion Dual-energy CT FVF allows for direct quantification of fat content in units of volume percent. Dual-energy CT FVF was larger in 30-cm than in 20-cm phantoms, though the effect of object size on fat estimation was less than that of CT attenuation on single-energy CT images. In the presence of iron, dual-energy CT FVF led to underestimateion of FVFref to a lesser degree than FF of MR spectroscopy led to overestimation of FVFref.

Regional glucose metabolic reduction in dementia with Lewy bodies is independent of amyloid deposition

PurposeThere is evidence that some cases of patients with dementia with Lewy bodies (DLB) can demonstrate Alzheimer disease (AD) like reduced glucose metabolism without amyloid deposition. The aim of this study was to clarify whether regional hypometabolism is related to amyloid deposits in the DLB brain and measure the degree of regional hypometabolism.MethodsTen consecutive subjects with DLB and 10 AD patients who underwent both Pittsburgh compound B (PiB)-PET and 18F-fluoro-2-deoxyglucose (FDG)-PET were included in this study. Regional standardized uptake value ratio (SUVR)s normalised to cerebellar cortices were calculated in the FDG- and PiB-PET images.ResultsAll AD patients and five DLB patients showed amyloid deposits (PiB positive). In the DLB group the parietotemporal and occipital metabolism were significantly lower than those in the AD group but there was no difference between the posterior cingulate hypometabolism between DLB and AD groups. There were no differences in regional glucose metabolism between PiB positive and negative DLB patients.ConclusionsIn the DLB brain, it is suggested that decreased regional glucose metabolism is unrelated to amyloid deposits, although the hypometabolic area overlaps with the AD hypometabolic area and the degree of parietotemporal and occipital hypometabolism in DLB brain is much larger than that in AD brain.