Yong Eun Chung

Added Value of Gadoxetic Acid-enhanced Hepatobiliary Phase MR Imaging in the Diagnosis of Hepatocellular Carcinoma

PURPOSE To determine the added value of hepatobiliary phase images in gadoxetic acid-enhanced magnetic resonance (MR) imaging in the evaluation of hepatocellular carcinoma (HCC). MATERIALS AND METHODS Institutional review board approved this retrospective study and waived the informed consent. Fifty-nine patients with 84 HCCs underwent gadoxetic acid-enhanced MR examinations that included 20-minute delayed hepatobiliary phase imaging. MR imaging was performed with a 1.5-T system in 19 patients and a 3.0-T system in 40 patients. A total of 113 hepatic nodules were documented for analysis. Three radiologists independently reviewed two sets of MR images: set 1, unenhanced (T1- and T2-weighted) and gadoxetic acid-enhanced dynamic images; set 2, hepatobiliary phase images and unenhanced and gadoxetic acid-enhanced dynamic images. For each observer, the diagnostic accuracy was compared by using the area under the alternative free-response receiver operating characteristic curve (A(z)). Sensitivity and specificity were also calculated and compared between the two sets. RESULTS For all observers, A(z) values were higher with the addition of the hepatobiliary phase. The observer who had the least experience in abdominal imaging (2 years) demonstrated significant improvement in A(z), from 0.895 in set 1 to 0.951 in set 2 (P = .049). Sensitivity increased with the addition of hepatobiliary phase images but did not reach statistical significance. Nine HCCs (10.7%) in six patients (10.1%) were seen only on hepatobiliary phase images. CONCLUSION Hepatobiliary phase images obtained after gadoxetic acid-enhanced dynamic MR imaging may improve diagnosis of HCC and assist in surgical planning.

Varying Appearances of Cholangiocarcinoma: Radiologic-Pathologic Correlation

Intrahepatic cholangiocarcinoma is the second most common primary hepatic tumor. Various risk factors have been reported for intrahepatic cholangiocarcinoma, and the radiologic and pathologic findings of this disease entity may differ depending on the underlying risk factors. Intrahepatic cholangiocarcinoma can be classified into three types on the basis of gross morphologic features: mass-forming (the most common), periductal infiltrating, and intraductal growth. At computed tomography (CT), mass-forming intrahepatic cholangiocarcinoma usually appears as a homogeneous low-attenuation mass with irregular peripheral enhancement and can be accompanied by capsular retraction, satellite nodules, and peripheral intrahepatic duct dilatation. Periductal infiltrating cholangiocarcinoma is characterized by growth along the dilated or narrowed bile duct without mass formation. At CT and magnetic resonance imaging, diffuse periductal thickening and increased enhancement can be seen with a dilated or irregularly narrowed intrahepatic duct. Intraductal cholangiocarcinoma may manifest with various imaging patterns, including diffuse and marked ductectasia either with or without a grossly visible papillary mass, an intraductal polypoid mass within localized ductal dilatation, intraductal castlike lesions within a mildly dilated duct, and a focal stricture-like lesion with mild proximal ductal dilatation. Awareness of the underlying risk factors and morphologic characteristics of intrahepatic cholangiocarcinoma is important for accurate diagnosis and for differentiation from other hepatic tumorous and nontumorous lesions.

Comparison of gadoxetic acid-enhanced dynamic imaging and diffusion-weighted imaging for the preoperative evaluation of colorectal liver metastases

To retrospectively compare the diagnostic accuracy for the detection of colorectal liver metastases between gadoxetic acid‐enhanced MRI (EOB‐MRI) and diffusion‐weighted imaging (DWI) on 3.0 Tesla (T) system, and then to determine whether a combination of the two techniques may improve the diagnostic performance.

Autologous bone marrow infusion activates the progenitor cell compartment in patients with advanced liver cirrhosis.

Several clinical trials of bone marrow cell infusion in patients with liver cirrhosis (LC) have shown clinical improvement, despite conflicting results from animal models. We investigated serial pathological features and the clinical impact after autologous bone marrow infusion (ABMI) in patients with advanced LC. Ten patients with advanced LC due to chronic hepatitis B virus infection underwent ABMI. Serological tests, MRI, and liver biopsies were performed, and quality of life was assessed by a questionnaire. Median serum albumin and hemoglobin levels increased significantly after ABMI. All patients showed an improvement in quality of life, with no serious adverse events. Liver volume, measured by MRI, increased in 80% of the patients, and ascites decreased after ABMI. Child-Pugh scores were also significantly improved at 6 months after ABMI. In the serially biopsied livers, a gradually increasing activation of the hepatic progenitor cell (HPC) compartment, including HPC activation (ductular reaction) and HPC differentiation (intermediate hepatocyte), reached a peak after 3 months, with continued proliferation of hepatocytes, and returned to baseline levels after 6 months. There was no significant change in grade or stage of liver fibrosis or stellate cell activation after ABMI. ABMI is suggested to improve liver function and to activate the progenitor cell compartment. Although clinical improvement was sustained for more than 6 months, histological changes in the liver returned to baseline 6 months after ABMI. Further comparative studies are warranted.

Hepatocellular carcinoma in patients with chronic liver disease: a comparison of gadoxetic acid-enhanced MRI and multiphasic MDCT.

AIM To compare the diagnostic performances of gadoxetic acid-enhanced magnetic resonance imaging (MRI) and multiphasic multidetector computed tomography (MDCT) in the detection of hepatocellular carcinoma (HCC) in patients with chronic liver disease. MATERIALS AND METHODS Institutional review board approval was obtained for this study and informed consent was obtained from all patients. Fifty-one patients (43 men, eight women; age range 32-80 years) with 73 HCCs underwent gadoxetic acid-enhanced MRI and multiphasic MDCT. Two readers independently analysed each image in three separate reading sessions. The alternative free-response receiver operating characteristic (AFROC) method was used to analyse the diagnostic accuracy. Positive and negative predictive values and sensitivity were evaluated. RESULTS A total of 73 HCCs were detected in 51 patients. Although not significant (p>0.05), the areas under the receiver operating characteristic curves were 0.877 and 0.850 for MDCT, 0.918 and 0.911 for dynamic MRI, and 0.905 and 0.918 for combined interpretation of dynamic and hepatobiliary phase MR images. Differences in sensitivity, specificity, and positive and negative predictive values between the readers were not statistically significant (p>0.05). Combined interpretation of dynamic and hepatobiliary phase MRI images was more useful than MDCT in the detection of HCC lesions ≤1cm in diameter for one reader (p=0.043). CONCLUSION Gadoxetic acid-enhanced MRI and MDCT show similar diagnostic performances for the detection of HCC in patients with chronic liver disease. However, the combined interpretation of dynamic and hepatobiliary phase MRI images may improve diagnostic accuracy in the detection of HCC lesions ≤1cm in diameter.

Rectal Cancer: Comparison of Accuracy of Local-Regional Staging with Two- and Three-dimensional Preoperative 3-T MR Imaging

PURPOSE To compare the local-regional staging accuracy of the conventional two-dimensional (2D) T2-weighted imaging protocol and of the three-dimensional (3D) T2-weighted imaging protocol for preoperative magnetic resonance (MR) imaging in rectal cancer patients. MATERIALS AND METHODS This retrospective study was approved by the institutional review board, and a waiver of informed consent was obtained. A review was conducted of 109 preoperative 3-T MR images obtained with 2D and 3D T2-weighted imaging protocols in rectal cancer patients. Two radiologists independently assessed the radiologic findings for T and N category lesions, conspicuity of tumor margin, and image quality of 2D and 3D data. Interactive multiplanar reconstruction was performed for 3D data analysis. The linear weighted kappa values for T2-weighted imaging staging results (2D and 3D data) and histopathologic staging results were calculated and compared. Wilcoxon signed rank test was performed to compare tumoral conspicuity and overall image quality. RESULTS T category lesion staging accuracy values for 2D and 3D data, respectively, were 66.0% and 67.0% for reviewer 1 (P = .465) and 63.3% and 56.9% for reviewer 2 (P = .402). N category lesion staging accuracy values for 2D and 3D T2-weighted images, respectively, were 64.2% and 57.8% for reviewer 1 (P = .427) and 47.7% and 62.4% for reviewer 2 (P = .666). Tumor conspicuity was better for 2D T2-weighted imaging, but no significant difference in image quality was observed. CONCLUSION Preoperative MR imaging in rectal cancer patients for staging with conventional 2D and multiplanar reconstruction 3D T2-weighted imaging protocols showed no significant differences in accuracy of T and N category staging and overall image quality, as determined by degree of artifact. However, the 3D T2-weighted imaging protocol had limitations in regard to lesion conspicuity.

Tumor perfusion‐related parameter of diffusion‐weighted magnetic resonance imaging: Correlation with histological microvessel density

We obtained intravoxel incoherent motion (IVIM) parameters through biexponential analysis on diffusion‐weighted MR imaging (DWI) using multiple b values. Correlation was evaluated between these parameters and histological microvessel density (MVD) for the possibility of noninvasive evaluation of MVD with DWI.

Comparison of MRI and Endoscopic Ultrasound in the Characterization of Pancreatic Cystic Lesions

OBJECTIVE The purpose of this study was to compare the diagnostic performance of MRI and endoscopic ultrasound (EUS) for the characterization of cystic pancreatic lesions and prediction of malignancy. MATERIALS AND METHODS Fifty patients (24 women and 26 men; average age, 57 years) underwent both MRI and EUS. All pancreatic lesions (21 cystic and 29 solid lesions) were proven by histopathologic analysis. Two radiologists retrospectively examined MR images, and a single gastroenterologist reviewed EUS images. The MRI and EUS characterizations of morphologic features of the cystic lesions and predictions of malignancy were evaluated. The prediction of malignancy was done by receiver operating characteristic (ROC) curve analysis. RESULTS There was no difference between the ability of MRI and EUS to correctly classify lesions as cystic or solid (accuracy, 90-98% vs 88%; p > 0.05). There was no difference between the sensitivity of MRI and EUS for the characterization of septa (94.4% for MRI vs 77.8% for EUS), mural nodule (66.7-58.3% for MRI vs 58.3% for EUS), main pancreatic duct dilatation (92.9-85.7% for MRI vs 85.7% for EUS), and communication with main pancreatic duct (100% for MRI vs 88.9% for EUS). The area under ROC curve values for predicting malignancy showed no statistical significance (0.755-0.774 for MRI vs 0.769 for EUS; p > 0.894). CONCLUSION MRI and EUS are comparable in the characterization of cystic pancreatic lesions and prediction of malignancy.

Abdominal Applications of 3.0-T MR Imaging: Comparative Review versus a 1.5-T System

With the development of dedicated receiver coils and increased gradient performance, 3.0-T magnetic resonance (MR) systems are gaining wider acceptance in clinical practice. The expected twofold increase in signal-to-noise ratio (SNR) compared with that of 1.5-T MR systems may help improve spatial resolution or increase temporal resolution when used with parallel acquisition techniques. Several issues must be considered when applying 3.0-T MR in the abdomen, including the alteration of the radiofrequency field and relaxation time, increase in energy deposition and susceptibility effects, and problems associated with motion artifacts. For the evaluation of liver lesions, higher SNR and greater resolution achieved with the 3.0-T system could translate into better detection of malignant lesions on T2-weighted images obtained with adjusted imaging parameters. For the evaluation of pancreatic and biliary diseases, high-resolution T2-weighted imaging using single-shot turbo spin-echo sequences is useful; improvement in SNR was noticeable on two-dimensional MR cholangiopancreatographic images. For the preoperative imaging of rectal cancer, a single-shot sequence is useful for dramatically decreasing imaging time while maintaining image quality. Substantial modification of examination protocols, with optimized imaging parameters and sequence designs along with ongoing development of hardware, could contribute to an increased role of the 3.0-T system for abdominal MR examinations.

Prediction of the histopathological grade of hepatocellular carcinoma using qualitative diffusion-weighted, dynamic, and hepatobiliary phase MRI.

ObjectivesTo investigate the effectiveness of qualitative diffusion-weighted imaging (DWI), subtraction of unenhanced from arterial phase images, and hepatobiliary phase (HBP) images in estimating the histopathological grade of hepatocellular carcinoma (HCC).MethodsWe retrospectively reviewed gadoxetic acid–enhanced magnetic resonance images of 175 patients with 201 surgically resected HCCs. The signal intensity and its relationship with histopathological grade were assessed for each sequence and a combination of sequences.ResultsThere was a tendency towards higher grades in tumours showing restricted diffusion on DWI (P < 0.001) or arterial enhancement on subtraction imaging (P <0.001), but not hepatocyte-defect on HBP images (P = 0.33). When lesions were divided into three groups based on combined findings on DWI and subtraction imaging, a linear trend was observed between group and grade (P < 0.001). The positive predictive value (PPV) of the combination of no restricted diffusion and no arterial enhancement in predicting well-differentiated HCC was 100%, higher than the PPV of individual findings on DWI (74%) or subtraction imaging (81%).ConclusionsDWI and subtraction imaging are helpful for predicting the histopathological grade of HCC, especially when the two sequences are considered together.Key Points• Predicting the histopathological grade of hepatocellular carcinoma (HCC) preoperatively is important.• Diffusion-weighted imaging (DWI) and subtraction imaging are recently developed MR techniques.• Retrospective study showed DWI and subtraction imaging helps predict HCC grades.• Management of patients with HCC becomes more appropriate.