Young Kon Kim

Differentiating mass-forming intrahepatic cholangiocarcinoma from atypical hepatocellular carcinoma using gadoxetic acid-enhanced MRI.

AIM To examine the differential features of mass-forming intrahepatic cholangiocarcinoma (ICC) from atypical hypovascular hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance imaging (MRI). MATERIALS AND METHODS The institutional review board approved this retrospective study and waived informed patient consent. Seventy patients with pathologically proven ICCs (35) and hypovascular atypical HCCs (35) who had undergone preoperative gadoxetic acid-enhanced MRI were enrolled in this study. Images were analysed for the shape of the lesions and presence of hyperintensity on the T1-weighted image (T1WI) and hypo- or hyperintense areas on the T2-weighted image (T2WI). In addition, images were analysed for the presence of linear hyperintensity or multifocal, tiny, hyperintense foci on T2WI and the presence of rim enhancement during early dynamic phases and a central enhancement with a hypointense rim (target appearance) on the 10 and 20 min hepatobiliary phase images. The significance of these findings was determined by the X(2) test. RESULTS Univariate analysis revealed that the following significant parameters favour ICC or hypovascular HCC; the presence of T2 hypo- and hyperintense areas and target appearance on the 10 min hepatobiliary phase images favour ICC, and the presence of T2 linear hyperintensity and T2 multifocal hyperintense foci favour hypovascular HCC (p < 0.05). Multivariate analysis revealed that only target appearance on the 10 min hepatobiliary phase was predictive of ICC (p = 0.002) as 30 ICCs (85.7%) showed this feature. However, the target appearance was also observed in all six scirrhous HCCs. CONCLUSION A target appearance on the 10 min hepatobiliary phase images is the best predictor for identifying mass-forming ICC at gadoxetic acid-enhanced MRI.

Validation of diagnostic criteria using gadoxetic acid-enhanced and diffusion-weighted MR imaging for small hepatocellular carcinoma (≤ 2.0 cm) in patients with hepatitis-induced liver cirrhosis

Background Gadoxetic acid and diffusion-weighted imaging (DWI) is increasingly used for the diagnosis of hepatocellular carcinoma (HCC). It is relevant to refine the diagnostic parameters for HCC, using state-of-the-art imaging techniques. Purpose To validate usefulness of magnetic resonance imaging (MRI) criteria with gadoxetic acid-enhanced MRI and DWI for diagnosis of small HCC by differentiation from dysplastic nodule (DN) or regenerative nodule (RN) in cirrhotic patients with strongly suspected small HCC. Material and Methods One hundred and eight patients with 102 HCCs and 29 benign nodules including 21 DNs and two large RNs (≤ 2.0 cm), and 40 patients with no HCC underwent gadoxetic acid-enhanced MRI and DWI. All patients also underwent MDCT. Index MR criteria for HCC were: (i) arterial hyperenhancement and hypointensity on hepatobiliary phase (HBP) with hyperintensity on DWI; (ii) hypovascular nodule with hyperintensity on DWI; (iii) arterial hyperenhancement and hypointensity on HBP without hyperintensity on DWI; (iv) arterial hyperenhancement and either iso- or hyperintensity on HBP, with hyperintensity on DWI; and (v) hyperintensity only on DWI. According to these criteria, MRI findings for HCCs and benign nodules were independently classified by two reviewers. Results On multidetector-row computed tomography, 64 HCCs (62.7%) showed typical features for HCC while 13 (12.8%) were not identified. On MRI, 84 HCCs (82.4%) showed arterial hyperenhancement and hypointensity on HBP, and hyperintensity on DWI. Eight HCCs were regarded as hypovascular HCCs with hyperintensity DWI (category 2). One HCC (0.6 cm in diameter) was demonstrated only by DWI. For each observer, 101 (99.0%) and 100 HCCs (98.0%) were discernible when applying all MRI criteria for HCC, respectively. Three DNs also fit the HCC criteria, thus the specificity was 90.9% for both observers. Conclusion With the HCC criteria based on combined gadoxetic acid-enhanced MRI and DWI, it is possible to reliably diagnose small HCC including hypovascular HCCs.

Differentiating combined hepatocellular and cholangiocarcinoma from mass-forming intrahepatic cholangiocarcinoma using gadoxetic acid-enhanced MRI

To examine the differential features of combined hepatocellular and cholangiocarcinoma (HCC‐CC) from mass‐forming intrahepatic cholangiocarcinoma (ICC) on gadoxetic acid‐enhanced MRI.

Diagnostic efficacy of gadoxetic acid-enhanced MRI for the detection and characterisation of liver metastases: comparison with multidetector-row CT

OBJECTIVES We compared the diagnostic performance of gadoxetic acid-enhanced MRI and 16-slice multidetector CT (MDCT) with respect to their abilities to detect hepatic metastases and differentiate hepatic metastases from hepatic cysts and haemangiomas. METHODS 67 patients with 110 liver metastases (size 0.3-2.5 cm), 33 haemangiomas (size 0.5-1.5 cm) and 17 cysts (size 0.3-1.0 cm) underwent 4-phase MDCT and gadoxetic acid-enhanced MRI, including early dynamic phases, post-contrast T(2) weighted turbo spin echo sequences and 20 min hepatocyte-selective phases. Two observers independently analysed each image in random order. Sensitivity and diagnostic accuracy for lesion detection and differentiation for MDCT and gadoxetic acid-enhanced MRI were calculated using receiver operating characteristic analysis. RESULTS For both observers, the Az values of gadoxetic acid-enhanced MRI (mean, 0.982 and 0.981) were significantly higher than the Az values of MDCT (mean, 0.839 and 0.892) (p<0.05) for the detection of metastases and for the differentiation of metastases from haemangiomas and cysts. Sensitivities of gadoxetic acid-enhanced MRI with regard to the detection and characterisation of liver metastases (mean, 96.9% and 96.0%) were significantly higher than those of MDCT (mean, 78.7% and 75.0%) (p<0.05). CONCLUSION Gadoxetic acid-enhanced MRI showed higher diagnostic accuracy and sensitivity than did MDCT for the detection of hepatic metastases and for the differentiation between hepatic metastases and hepatic haemangiomas or cysts.

Detection of hepatocellular carcinoma in gadoxetic acid-enhanced MRI and diffusion-weighted MRI with respect to the severity of liver cirrhosis

Background As gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) have been widely used for the evaluation of hepatocellular carcinoma (HCC), it is clinically relevant to determine the diagnostic efficacy of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Purpose To compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Material and Methods A total of 189 patients with 240 HCCs (≤3.0 cm) (Child-Pugh A, 81 patients with 90 HCCs; Child-Pugh B, 65 patients with 85 HCCs; Child-Pugh C, 43 patients with 65 HCCs) underwent DWI and gadoxetic acid-enhanced MRI at 3.0 T. A gadoxetic acid set (dynamic and hepatobiliary phase plus T2-weighted image) and DWI set (DWI plus unenhanced MRIs) for each Child-Pugh class were analyzed independently by two observers for detecting HCCs using receiver-operating characteristic analysis. The diagnostic accuracy and sensitivity were calculated. Results There was a trend toward decreased diagnostic accuracy for gadoxetic acid and DWI set with respect to the severity of cirrhosis (Child-Pugh A [mean 0.974, 0.961], B [mean 0.904, 0.863], C [mean 0.779, 0.760]). For both observers, the sensitivities of both image sets were highest in Child-Pugh class A (mean 95.6%, 93.9%), followed by class B (mean 83.0%, 77.1%), and class C (mean 60.6%, 60.0%) (P < 0.05). Conclusion In HCC detection, the diagnostic accuracy and sensitivity for gadoxetic acid-enhanced MRI and DWI were highest in Child-Pugh class A, followed by Child-Pugh class B, and Child-Pugh class C, indicating a tendency toward decreased diagnostic capability with the severity of cirrhosis.

Imaging features of small (≤3 cm) pancreatic solid tumors on gadoxetic-acid-enhanced MR imaging and diffusion-weighted imaging: an initial experience

OBJECTIVE The objective was to determine imaging features that distinguish small (≤3cm) solid pancreatic adenocarcinoma, neuroendocrine tumor (NET) and solid pseudopapillary tumor (SPT) on gadoxetic-acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighed imaging (DWI). MATERIALS AND METHODS Twenty-four adenocarcinomas, 10 NETs and 8 SPTs were retrospectively included. Two radiologists analyzed morphologic features, signal intensity of the tumors on MR images including DWI (b=800) and dynamic enhancement pattern with consensus. Tumor-to-parenchyma ratio and tumor apparent diffusion coefficients (ADCs) were quantitatively assessed. RESULTS All adenocarcinomas had an ill-defined margin and irregular shape, and more frequently had pancreatic duct dilatation compared with other tumors (P<.05). All SPTs and all but one of the adenocarcinomas (95.8%) had no arterial enhancement with progressively increased enhancement, whereas seven NETs (70%) had arterial enhancement with progressively decreased enhancement (P<.01). The mean value of tumor-to-parenchyma ratio on arterial and portal phases was significantly higher for NETs, and the mean value of tumor ADCs was significantly lower for SPTs than for other tumors (P<.05). CONCLUSIONS Gadoxetic-acid-enhanced MRI may aid in differentiation between small adenocarcinomas, NETs and SPTs based on morphologic features with dynamic enhancement pattern in adenocarcinomas, dynamic enhancement pattern with tumor-to-parenchyma ration on arterial and portal phases in NETs, and dynamic enhancement pattern with lower ADC value in SPTs.

Transthoracic needle biopsy using a C-arm cone-beam CT system: diagnostic accuracy and safety

OBJECTIVE The purpose of this study was to evaluate the diagnostic accuracy and safety of performing transthoracic needle biopsy (TNB) under combined fluoroscopy and CT guidance using a C-arm cone-beam CT (CBCT) system. METHODS We evaluated the diagnostic accuracy and safety of performing TNB using a C-arm CBCT system. We retrospectively evaluated 99 TNB cases performed in 98 patients using a C-arm CBCT system with an 18-gauge automated cutting needle. We reviewed the diagnostic accuracy according to the size and depth of the lesion, incidence of complications, additional treatment for complications, procedure time, number of needle passes per biopsy and radiation dose. RESULTS The final diagnoses revealed 72 malignant and 27 benign lesions. The overall malignancy sensitivity, malignancy specificity and diagnostic accuracy were 95.8%, 100% and 97.0%, respectively, and those for small pulmonary nodules <20 mm in size were 94.1%, 100% and 96.6%, respectively. There was no significant difference in the correct diagnosis of malignancy according to lesion size (p = 0.634) or depth (p = 0.542). For benign lesions, a specific diagnosis was obtained in 14 cases (51.9%). TNB induced complications in 19 out of 99 procedures (19.2%), including pneumothorax (16.2%), immediate haemoptysis (2.0%) and subcutaneous emphysema (1.0%). Among these, four patients with pneumothorax required chest tube insertion (2.0%) or pig-tail catheter drainage (2.0%). The mean procedure time, number of needle passes and radiation doses were 11.9 ± 4.0 min, 1.2 ± 0.5 times and 170.0 ± 67.2 mGy, respectively. CONCLUSION TNB using a C-arm CBCT system provides high diagnostic accuracy with a low complication rate and a short procedure time, particularly for small pulmonary nodules.

Imaging features of subcentimeter hypointense nodules on gadoxetic acid-enhanced hepatobiliary phase MR imaging that progress to hypervascular hepatocellular carcinoma in patients with chronic liver disease.

Background: With the advent of 3-T magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI), many subcentimeter hepatic nodules have been frequently detected in patients with chronic liver disease, and the prediction of subcentimeter nodules that progress to hypervascular hepatocellular carcinoma (HCC) is important. Purpose: To reveal the imaging features of subcentimeter hypointense nodules on gadoxetic acid-enhanced hepatobiliary phase MR images in patients with chronic liver disease that may be related with progression to hypervascular HCC. Material and Methods: This study included 109 patients with 135 subcentimeter hypointense nodules (103 hepatocellular carcinomas [HCCs] and 32 benign nodules) on gadoxetic acid-enhanced hepatobiliary phase. For each subcentimeter nodule, the following imaging features were analyzed: (i) hyperintensity on T2-weighted (T2W) image or DWI; (ii) arterial hypervascularization; and (iii) hypointensity on a portal or late phase. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of those imaging features for predicting subcentimeter nodules that progressed to hypervascular HCC were evaluated. Volume doubling time (VDT) of subcentimeter nodules that progressed to hypervascular HCC was compared to that of growing benign nodules. Results: Arterial hypervascularization with washout yielded the highest specificity (90.6%) and PPV (95.4%) for prediction of subcentimeter nodules that progressed to hypervascular HCC. Combining hyperintensity on T2W image or DWI and arterial hypervascularization with washout did not raise the specificity (90.6%) for prediction of subcentimeter nodules that progressed to hypervascular HCC. Mean VDT (112.2 ± 106.3 days) of subcentimeter nodules that progressed to hypervascular HCC during follow-up was significantly shorter than those of benign subcentimeter nodules (1258 ± 766.5 days, P < 0.001). Conclusion: Arterial hypervascularization with washout in subcentimeter hypointense nodules on gadoxetic acid-enhanced hepatobiliary phase in patients with chronic liver disease is strongly related with progression to hypervascular HCC.

Noncontrast MRI with diffusion-weighted imaging as the sole imaging modality for detecting liver malignancy in patients with high risk for hepatocellular carcinoma

PURPOSE To compare the diagnostic performance of the noncontrast MRI including DWI to the standard MRI for detecting hepatic malignancies in patients with chronic liver disease. MATERIALS AND METHODS We included 135 patients with 136 histologically-confirmed hepatocellular carcinomas (HCCs), 12 cholangiocarcinomas, and 34 benign lesions (≤ 2.0 cm), and 22 patients with cirrhosis but no focal liver lesion who underwent 3.0 T liver MRI. Noncontrast MRI set (T1- and T2-weighted images and DWI) and standard MRI set (gadoxetic acid-enhanced and noncontrast MRI) were analyzed independently by three observers to detect liver malignancies using receiver operating characteristic analysis. RESULTS The Az value of the noncontrast MRI (mean, 0.906) was not inferior to that of the combined MRI (mean, 0.924) for detecting malignancies by all observers (P>0.05). For each observer, no significant difference was found in the sensitivity and specificity between the two MRI sets for detecting liver malignancies and distinguishing them from benign lesions (P>0.05), whereas negative predictive value was higher with the combined MRI than with the noncontrast MRI (P=0.0001). When using pooled data, the sensitivity of the combined MRI (mean 94.8%) was higher than that of the noncontrast MRI (mean, 91.7%) (P =0.001), whereas specificity was equivalent (78.6% vs 77.5%). CONCLUSION Noncontrast MRI including DWI showed reasonable performance compared to the combined gadoxetic acid-enhanced and noncontrast MRI set for detecting HCC and cholangiocarcinoma and differentiating them from benign lesions in patients with chronic liver disease.

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.