Jeong-Hee Yoon

Hepatocellular Carcinoma: Imaging Patterns on Gadoxetic Acid–enhanced MR Images and Their Value as an Imaging Biomarker

PURPOSEnTo investigate the patterns of imaging appearance of hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced magnetic resonance (MR) images and to assess their potential value as prognostic markers of HCC associated with tumor recurrence after surgery.nnnMATERIALS AND METHODSnThe institutional review board approved this retrospective study and informed consent was waived. A total of 216 patients with 304 pathologically proved HCCs underwent gadoxetic acid-enhanced MR imaging prior to surgery and were included in the study. Two reviewers, blinded to the clinical data, evaluated in consensus the imaging patterns of HCC according to enhancement patterns on dynamic phase images and signal intensity on hepatobiliary phase (HBP) images. The association of imaging features with clinical-pathologic findings was evaluated by using the Student t test, χ(2) test, Mann-Whitney U test, and linear-by-linear association. The dependence of time to tumor recurrence (TTR) after surgery was evaluated by using the Kaplan-Meier method, log-rank test, and Cox proportional hazard model.nnnRESULTSnHCCs with atypical enhancement pattern (P = .0167, P = .0450, P < .0001, respectively) and iso- to hyperintensity on HBP images (P = .0001, P = .0002, P < .0001, respectively) had smaller tumor size, lower histologic grade, and worse Child-Pugh class. The log-rank test (P = .0064) and Cox proportional hazards model (hazard ratio, 5.676; P = .0158) revealed that HCCs with iso- to hyperintensity on HBP images had significantly longer TTR than HCCs with hypointensity on HBP images.nnnCONCLUSIONnHCCs can be classified into several imaging patterns on gadoxetic acid-enhanced MR images, which are associated with tumor aggressiveness and outcome. In addition, iso- to hyperintensity on HBP images may be a useful imaging biomarker to indicate longer TTR after surgery. .

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.

Low Tube Voltage Intermediate Tube Current Liver MDCT: Sinogram-Affirmed Iterative Reconstruction Algorithm for Detection of Hypervascular Hepatocellular Carcinoma

OBJECTIVEnThe purpose of this study was to compare image quality and lesion detectability in the evaluation of hypervascular hepatocellular carcinoma (HCC) on low-tube-voltage half-dose liver CT scans subjected to sinogram-affirmed iterative reconstruction (SAFIRE) with the quality and detectability on full-dose scans reconstructed with filtered back projection (FBP).nnnMATERIALS AND METHODSnA total of 126 patients with suspected HCC who underwent liver CT including arterial phase scanning at 80 kVp in the dual-source mode (300 mAs for each tube) were included in the study. The half-dose arterial scans were reconstructed with FBP, iterative reconstruction in image space (IRIS), and five SAFIRE strengths (S1-S5) and were compared with full-dose virtual scans (600 mA) reconstructed with FBP. We assessed image noise, contrast-to-noise ratio (CNR) of the liver and blood vessels, and lesionto-liver CNR. Two radiologists evaluated image quality and lesion detectability attained with the different imaging sets.nnnRESULTSnImage noise on SAFIRE images was significantly lower than that on the other images, and the CNRs on SAFIRE images were higher than those on half-dose FBP images (p < 0.001). In addition, lesion-to-liver CNR on the half-dose S5 SAFIRE images was higher than on IRIS and full-dose FBP images (p < 0.05). Among the half-dose scans, SAFIRE images had significantly better image quality than FBP images (p < 0.05). Regarding lesion detection, half-dose SAFIRE images were better than half-dose FBP images and were comparable with full-dose FBP images (observer 1, 91.8% vs 96%; observer 2, 98% vs 98%; p > 0.05).nnnCONCLUSIONnPerforming half-dose 80-kVp liver CT with SAFIRE technique may increase image quality and afford comparable lesion detectability of hypervascular HCC at a reduced radiation dose compared with full-dose CT with FBP.

Small (≤1-cm) Hepatocellular Carcinoma: Diagnostic Performance and Imaging Features at Gadoxetic Acid–enhanced MR Imaging

PURPOSEnTo assess diagnostic performance and imaging features of gadoxetic acid-enhanced magnetic resonance (MR) imaging in small (≤1-cm) hepatocellular carcinoma (HCC) detection in patients with chronic liver disease.nnnMATERIALS AND METHODSnThe institutional review board approved this retrospective study and waived informed consent. Sixty patients (56 men, four women; mean age, 60.1 years) with HCC (146 lesions; 70 > 1 cm, 76 ≤ 1 cm) underwent gadoxetic acid-enhanced MR imaging. HCC was confirmed at surgical resection (72 lesions; 30 > 1 cm, 42 ≤ 1 cm) or by showing interval growth with typical enhancement patterns at follow-up dynamic computed tomography or MR imaging (74 lesions; 40 > 1 cm, 34 ≤ 1 cm). Two radiologists assessed MR imaging features and graded likelihood of HCC with a five-point confidence scale. Jackknife alternative free-response receiver operating characteristic (JAFROC) method was used.nnnRESULTSnMean JAFROC figure of merit for small HCC was 0.717; that for large (>1-cm) HCC was 0.973 with substantial agreement (κ = 0.676). Mean sensitivity and positive predictive value (PPV) were 46.0% (70 of 152) and 48.3% (70 of 145) for small HCC versus 95.0% (133 of 140) and 78.2% (133 of 170) for large HCC, respectively. Eleven of 76 small HCCs (14%) were not seen on MR images, even after careful investigation. MR imaging features of small HCC included arterial enhancement (79%, 60 of 76), hypointensity on hepatobiliary phase (HBP) images (68%, 52 of 76), washout on 3-minute delayed phase images (50%, 38 of 76), hyperintensity on T2-weighted images (43%, 33 of 76), hypointensity on T1-weighted images (32%, 24 of 76), and restriction on diffusion-weighted images (28%, 20 of 72). Arterial enhancement and washout on 3-minute delayed phase images or hypointensity on HBP images occurred in 66% of small HCCs (50 of 76).nnnCONCLUSIONnDiagnostic performance of gadoxetic acid-enhanced MR imaging for small HCC detection is still low, with mean sensitivity of 46.0% (70 of 152) and mean PPV of 48.3% (70 of 145). By adding hypointensity on HBP images as washout, diagnostic performance for small HCC detection can be improved.

Diagnosis of Hepatocellular Carcinoma: Newer Radiological Tools

With the recent dramatic advances in diagnostic modalities, the diagnosis of hepatocellular carcinoma (HCC) is primarily based on imaging. Ultrasound (US) plays a crucial role in HCC surveillance. Dynamic multiphasic multidetector-row CT (MDCT) and magnetic resonance imaging (MRI) are the standard diagnostic methods for the noninvasive diagnosis of HCC, which can be made based on hemodynamic features (arterial enhancement and delayed washout). The technical development of MDCT and MRI has made possible the fast scanning with better image quality and resolution, which enables an accurate CT hemodynamic evaluation of hepatocellular tumor, as well as the application of perfusion CT and MRI in clinical practice. Perfusion CT and MRI can measure perfusion parameters of tumor quantitatively and can be used for treatment response assessment to anti-vascular agents. Besides assessing the hemodynamic or perfusion features of HCC, new advances in MRI can provide a cellular information of HCC. Liver-specific hepatobiliary contrast agents, such as gadoxetic acid, give information regarding hepatocellular function or defect of the lesion, which improves lesion detection and characterization. Diffusion-weighted imaging (DWI) of the liver provides cellular information of HCC and also has broadened its role in lesion detection, lesion characterization, and treatment response assessment to chemotherapeutic agents. In this article, we provide an overview of the state-of-the art imaging techniques of the liver and their clinical role in management of HCC.

Recent Advances in CT and MR Imaging for Evaluation of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Accurate diagnosis and assessment of disease extent are crucial for proper management of patients with HCC. Imaging plays a crucial role in early detection, accurate staging, and the planning of management strategies. A variety of imaging modalities are currently used in evaluating patients with suspected HCC; these include ultrasound, computed tomography (CT), magnetic resonance imaging (MRI), nuclear medicine, and angiography. Among these modalities, dynamic MRI and CT are regarded as the best imaging techniques available for the noninvasive diagnosis of HCC. Recent improvements in CT and MRI technology have made noninvasive and reliable diagnostic assessment of hepatocellular nodules possible in the cirrhotic liver, and biopsy is frequently not required prior to treatment. Until now, the major challenge for radiologists in imaging cirrhosis has been the characterization of small cirrhotic nodules smaller than 2 cm in diameter. Further technological advancement will undoubtedly have a major impact on liver tumor imaging. The increased speed of data acquisition in CT and MRI has allowed improvements in both spatial and temporal resolution, which have made possible a more precise evaluation of the hemodynamics of liver nodules. Furthermore, the development of new, tissue-specific contrast agents such as gadoxetic acid has improved HCC detection on MRI. In this review, we discuss the role of CT and MRI in the diagnosis and staging of HCC, recent technological advances, and the strengths and limitations of these imaging modalities.

Diagnostic value of computed tomographic findings of nutcracker syndrome: Correlation with renal venography and renocaval pressure gradients

PURPOSEnTo evaluate the diagnostic values of CT findings of nutcracker syndrome (NCS).nnnMETHODS AND MATERIALSnTwenty seven subjects that underwent CT and renal venography, were divided into three groups based on the venographic renocaval pressure gradient (PG) and collateral veins of the left renal vein (LRV): non-compensated NCS patients with PG≥3 mm Hg (group 1, n=12), partially compensated NCS patients with borderline PG (1<3 mm Hg) and collateral veins (group 2, n=6), and control group with low PG (0-1 mm Hg) without collateral veins (group 3, n=9). The CT findings were analyzed with regard to abrupt narrowing of the LRV with an acute angle (beak sign), aortomesenteric angle between the superior mesenteric artery and aorta on sagittal images, and LRV diameter ratio (hilar-aortomesenteric).nnnRESULTSnBeak sign of the LRV was found in 91.7% (11/12) of group 1, 50% (3/6) of group 2, and in 11.1% (1/9) of group 3 with the significant difference between groups 1 and 3 (P<.05, χ2 test). Mean values of all quantitative CT parameters differed significantly only between groups 1 and 3 (P<.05, one-way ANOVA test). For differentiating the non-compensated NCS from the control group, the beak sign showed 91.7% sensitivity and 88.9% specificity. Of the various CT parameters, the beak sign and LRV diameter ratio of ≥4.9 showed the greatest diagnostic accuracy (AUC 0.903, ROC analysis).nnnCONCLUSIONnBeak sign of the LRV and CT findings can be useful in diagnosing the non-compensated NCS.

MR Imaging in Patients with Suspected Liver Metastases: Value of Liver-Specific Contrast Agent Gadoxetic Acid

Objective To compare the diagnostic performance of gadoxetic acid-enhanced magnetic resonance (MR) imaging with that of triple-phase multidetector-row computed tomography (MDCT) in the detection of liver metastasis. Materials and Methods Our institutional review board approved this retrospective study and waived informed consent. The study population consisted of 51 patients with hepatic metastases and 62 patients with benign hepatic lesions, who underwent triple-phase MDCT and gadoxetic acid-enhanced MRI within one month. Two radiologists independently and randomly reviewed MDCT and MRI images regarding the presence and probability of liver metastasis. In order to determine additional value of hepatobiliary-phase (HBP), the dynamic-MRI set alone and combined dynamic-and-HBP set were evaluated, respectively. The standard of reference was a combination of pathology diagnosis and follow-up imaging. For each reader, diagnostic accuracy was compared using the jackknife alternative free-response receiver-operating-characteristic (JAFROC). Results For both readers, average JAFROC figure-of-merit (FOM) was significantly higher on the MR image sets than on the MDCT images: average FOM was 0.582 on the MDCT, 0.788 on the dynamic-MRI set and 0.847 on the combined HBP set, respectively (p < 0.0001). The differences were more prominent for small (≤ 1 cm) lesions: average FOM values were 0.433 on MDCT, 0.711 on the dynamic-MRI set and 0.828 on the combined HBP set, respectively (p < 0.0001). Sensitivity increased significantly with the addition of HBP in gadoxetic acid-enhanced MR imaging (p < 0.0001). Conclusion Gadoxetic acid-enhanced MRI shows a better performance than triple-phase MDCT for the detection of hepatic metastasis, especially for small (≤ 1 cm) lesions.

Clinical application of controlled aliasing in parallel imaging results in a higher acceleration (CAIPIRINHA)-volumetric interpolated breathhold (VIBE) sequence for gadoxetic acid-enhanced liver MR imaging.

To determine whether a controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) technique can improve the image quality of three‐dimensional (3D), T1‐weighted gradient echo (T1w‐GRE) imaging compared with the use of a standard, parallel acquisition technique (PAT).

Role of C-Arm CT for Transcatheter Arterial Chemoembolization of Hepatocellular Carcinoma: Diagnostic Performance and Predictive Value for Therapeutic Response Compared With Gadoxetic Acid–Enhanced MRI

OBJECTIVEnThe objective of our study was to investigate the diagnostic performance of C-arm CT and its value to predict response of hepatocellular carcinoma (HCC) to trans-catheter arterial chemoembolization (TACE) compared with gadoxetic acid-enhanced MRI.nnnMATERIALS AND METHODSnSixty-eight patients with HCCs (n=167; 145>1 cm, 22≤1 cm) underwent both C-arm CT immediately before TACE and gadoxetic acid-enhanced MRI within 2 weeks before TACE. Two radiologists rated the possibility of HCC using a 5-point confidence scale focused on the degree of arterial enhancement and the shape of the lesion seen on C-arm CT. They also graded the possibility of HCC on MRI based on the signal intensities on T1- and T2-weighted images, arterial enhancement, and hypointensity on both the late phase and the hepatobiliary phase. We also measured the apparent diffusion coefficient value. The diagnostic accuracy was evaluated using the alternative free-response receiver operating characteristic curve method. A multivariate logistic regression analysis was performed between the good-response and nonresponse HCCs for TACE.nnnRESULTSnThe diagnostic accuracy of MRI was greater than that of C-arm CT (0.890 vs 0.681, respectively; p<0.001). However, in small HCCs (≤1 cm), C-arm CT showed a higher sensitivity than MRI (90.9% vs 70.5%, respectively; p=0.023) and a lower positive predictive value than MRI (40.8% vs 57.4%, p=0.073). Well-defined strong arterial enhancement on C-arm CT (odds ratio=8.08, p=0.05) was statistically significant for predicting therapeutic response of HCC to TACE.nnnCONCLUSIONnC-arm CT showed greater sensitivity than gadoxetic acid-enhanced MRI in depicting small HCCs (≤1 cm). Furthermore, well-defined strong arterial enhancement on C-arm CT can be used to predict therapeutic response of HCC to TACE.