Tomoaki Ichikawa

Imaging Study of Early Hepatocellular Carcinoma: Usefulness of Gadoxetic Acid–enhanced MR Imaging

PURPOSE To describe imaging findings of early hepatocellular carcinoma (HCC) at gadoxetic acid-enhanced magnetic resonance (MR) imaging, dynamic contrast material-enhanced computed tomography (CT), CT during arterial portography (CTAP), and CT during hepatic arteriography (CTHA) and to compare the diagnostic performance of each modality for small (≤ 2 cm) HCC. MATERIALS AND METHODS The institute ethics committee deemed study approval unnecessary. One hundred eight resected small lesions in 64 patients were diagnosed as a dysplastic nodule (DN) (n = 12), progressed HCC (n = 66), or early HCC (n = 30). All but two patients underwent all imaging examinations. The imaging characteristics of the lesions with each modality were determined. To evaluate the diagnostic performance of the modalities, two radiologists graded the presence of HCC with use of a five-point confidence scale. The area under the receiver operating characteristic curve (A(z)), sensitivity, and specificity of each modality were compared. RESULTS The imaging features that are statistically significant for differentiating an early HCC from a DN include fat-containing lesions at dual-echo T1-weighted MR imaging (seen in 16 of the 30 early HCCs and none of the DNs), low attenuation at unenhanced CT (seen in 13 of the 30 early HCCs and none of the DNs), low attenuation at CTAP (seen in 11 of the 30 early HCCs and none of the DNs), and low signal intensity at hepatocyte phase gadoxetic acid-enhanced MR imaging (seen in 29 of the 30 early HCCs and none of the DNs). The diagnostic performance of gadoxetic acid-enhanced MR imaging (A(z), 0.98 and 0.99) was significantly greater than that of contrast-enhanced CT (A(z), 0.87) and CTHA-CTAP (A(z), 0.85 and 0.86) owing to its significantly higher sensitivity (P < .001). CONCLUSION Gadoxetic acid-enhanced MR imaging is the most useful imaging technique for evaluating small HCC, including early HCC.

Detection and characterization of focal liver lesions: a Japanese phase III, multicenter comparison between gadoxetic acid disodium-enhanced magnetic resonance imaging and contrast-enhanced computed tomography predominantly in patients with hepatocellular carcinoma and chronic liver disease.

Objectives:To prospectively evaluate the safety and efficacy of combined unenhanced and gadoxetic acid disodium (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging compared with unenhanced MR imaging and triphasic contrast-enhanced spiral computed tomography (CT) for the detection and characterization of focal liver lesions. Materials and Methods:The study was reviewed and approved by the institutional review board at each of the 15 centers involved in the study, and informed written consent was given by all patients. In total, 178 patients with suspected focal hepatic lesions (based, in most patients, on CT, tumor marker and ultrasound examinations) underwent combined MR imaging with a single, rapid injection of Gd-EOB-DTPA 0.025 mmol/kg, including T1-weighted dynamic and delayed MR images 20 to 40 minutes postinjection. Triphasic contrast-enhanced CT, the comparator examination, was performed within 4 weeks of MR imaging. Standard of references (SOR) were resection histopathology and intraoperative ultrasonography, or combined CT during arterial portography and CT hepatic arteriography; in cases where, although the major lesions were treated, some lesion(s) were not treated, follow-up superparamagnetic iron oxide-enhanced MR imaging was additionally performed. All images were assessed for differences in lesion detection and characterization (specific lesion type) by on-site readers and 3, blinded (off-site) reviewers. All adverse events (AEs) occurring within 72 hours after Gd-EOB-DTPA administration were reported. Results:Overall, 9.6% of patients who received Gd-EOB-DTPA reported 21 drug-related AEs. A total of 151 patients were included in the efficacy analysis. Combined MR imaging showed statistically higher sensitivity in lesion detection (67.5%–79.5%) than unenhanced MR imaging (46.5%–59.1%; P < 0.05 for all). Combined MR imaging also showed higher sensitivity in lesion detection than CT (61.1%–73.0%), with the results being statistically significant (P < 0.05) for on-site readers and 2 of 3 blinded readers. Higher sensitivity in lesion detection with combined MR imaging compared with CT was also clearly demonstrated in the following subgroups: lesions with a diameter ≤20 mm (lesions ≤10 mm: 38.0%–55.4% vs. 26.1%–47.3%, respectively; lesions 10–20 mm: 71.1%–87.3% vs. 65.7%–78.4%, respectively); in cirrhotic patients (64.5%–75.4% vs. 54.5%–70.3%, respectively); and in patients with hepatocellular carcinoma (66.6%–78.6% vs. 59.1%–71.6%, respectively). Combined MR imaging demonstrated a higher proportion of correctly characterized lesions (50.5%–72.1%) than unenhanced MR imaging (30.2%–50.0%; P < 0.05 for all), whereas there were no significant differences compared with CT (49.0%–68.1%), except for one blinded reader (P < 0.05). Conclusion:In this study, hepatocyte-specific Gd-EOB-DTPA was shown to be safe and to improve the detection and characterization of focal hepatic lesions compared with unenhanced MR imaging. When compared with spiral CT, Gd-EOB-DTPA enhanced MRI seems to be beneficial especially for the detection for smaller lesions or hepatocellular carcinoma underlying cirrhotic liver.

Diffusion-weighted MR imaging with single-shot echo-planar imaging in the upper abdomen: preliminary clinical experience in 61 patients

AbstractBackground: To determine the potential ability of diffusion-weighted magnetic resonance (MR) imaging with single-shot echo-planar imaging (DW imaging) in the upper abdomen by apparent diffusion coefficient (ADC) and signal:intensity ratio (SIR) measurements. Methods: DW imaging was performed in 61 clinical patients. ADCs in the liver, pancreas, spleen, kidney, and different pathological conditions were calculated. Spleen-to-liver SIR and segmental intensity difference of the liver (SID) were also calculated. Results: The mean ADCs (mm2/s) were 2.28 × 10−3± 0.07 in the liver, 1.44 × 10−3± 0.05 in the spleen, 1.94 × 10−3± 0.19 in the pancreas, and 5.76 × 10−3± 0.06 in the kidney. The mean ADC of cirrhotic liver was 1.96 × 10−3± 0.62, which was lower than that of normal liver. Other pathologic conditions also showed ADCs different from those of normal tissues. All DW images showed significantly higher spleen-to-liver SIRs and SIDs than did T2-weighted images (p < 0.05). Conclusion: The mean ADCs obtained with DW imaging were different in each upper abdominal organ and with each pathologic condition. DW images showed better soft tissue contrast than did T2-weighted images with regard to SIR and CNR in depicting and characterizing upper abdominal disorders.

Liver parenchymal enhancement of hepatocyte-phase images in Gd-EOB-DTPA-enhanced MR imaging: which biological markers of the liver function affect the enhancement?

To clarify the factors that predict enhancement of the liver parenchyma in hepatocyte‐phase of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd‐EOB‐DTPA)‐enhanced MR imaging.

Distinguishing Hypervascular Pseudolesions of the Liver from Hypervascular Hepatocellular Carcinomas with Gadoxetic Acid-enhanced MR Imaging

PURPOSE To retrospectively determine findings at gadoxetic acid-enhanced magnetic resonance (MR) imaging in hypervascular pseudolesions that were observed at computed tomography (CT) during hepatic arteriography, with special focus on distinguishing these pseudolesions from hypervascular hepatocellular carcinomas (HCCs). MATERIALS AND METHODS The institute ethics committee deemed study approval unnecessary. The study population comprised 80 patients (55 men, 25 women) with chronic liver disease who underwent CT during hepatic arteriography and arterial portography, gadoxetic acid-enhanced MR imaging, and follow-up dynamic contrast material-enhanced CT. The diagnosis of 104 pseudolesions and 123 HCCs was confirmed by means of histopathologic or multimodality evaluation. Two radiologists assessed the MR imaging findings of HCCs and pseudolesions in consensus, including the signal intensities (SIs) of the lesions on T2-weighted, diffusion-weighted (DW), and contrast-enhanced hepatocyte-phase images. The findings of nodular pseudolesions and HCCs were compared with the Fisher exact test. Additionally, the hepatocyte-phase SI ratio (ratio of lesion SI to liver SI) for HCCs and pseudolesions was compared by means of the Mann-Whitney U test. RESULTS There were 62 wedge-shaped, 32 nodular, and 10 linear pseudolesions. On gadoxetic acid-enhanced hepatocyte-phase MR images, 15% of pseudolesions (16 of 104) were hypointense compared with surrounding liver tissue. The mean hepatocyte-phase SI ratio of HCCs (0.65 +/- 0.14 [standard deviation]) was significantly lower (P < .01) than that of the nodular pseudolesions (0.95 +/- 0.11). The optimal cutoff value of hepatocyte-phase SI ratio for distinguishing between HCC and nodular pseudolesion was 0.84. No nodular pseudolesions were visible on DW images. CONCLUSION Gadoxetic acid-enhanced hepatocyte-phase MR imaging and DW imaging could be used to distinguish hypervascular pseudolesions from hypervascular HCCs; a hepatocyte-phase SI ratio below 0.84 and visibility on DW images were findings specific for HCCs rather than pseudolesions.

High-b-value diffusion-weighted MR imaging of hepatocellular lesions: Estimation of grade of malignancy of hepatocellular carcinoma

To evaluate the effectiveness of diffusion‐weighted magnetic resonance imaging (DWI) in estimating the grade of malignancy of hepatocellular carcinoma.

Diagnosis of colorectal hepatic metastases: Comparison of contrast‐enhanced CT, contrast‐enhanced US, superparamagnetic iron oxide‐enhanced MRI, and gadoxetic acid‐enhanced MRI

To compare the diagnostic accuracy of contrast‐enhanced computed tomography (CE‐CT), contrast‐enhanced ultrasonography (CE‐US), superparamagnetic iron oxide‐enhanced magnetic resonance imaging (SPIO‐MRI), and gadoxetic acid‐enhanced MRI (Gd‐EOB‐MRI) in the evaluation of colorectal hepatic metastases.

Additional value of gadoxetic acid-DTPA-enhanced hepatobiliary phase MR imaging in the diagnosis of early-stage hepatocellular carcinoma: comparison with dynamic triple-phase multidetector CT imaging.

To assess the value of hepatobiliary phase gadoxetic acid (EOB)‐enhanced magnetic resonance imaging (MRI) for the diagnosis of early stage hepatocellular carcinoma (HCC) (<3 cm) compared to triple‐phase dynamic multidetector computed tomography (MDCT).

Detection of Pancreatic Carcinoma and Liver Metastases with Gadoxetic Acid–enhanced MR Imaging: Comparison with Contrast-enhanced Multi–Detector Row CT

PURPOSE To intraindividually compare gadoxetic acid-enhanced magnetic resonance (MR) imaging with contrast material-enhanced multi-detector row computed tomography (CT) in detection of pancreatic carcinoma and liver metastases. MATERIALS AND METHODS The ethics committee approved this retrospective study with waiver of informed consent. This study included 100 patients (53 men, 47 women; mean age, 67.8 years) consisting of 54 patients with pathologically confirmed pancreatic carcinoma (mean size, 33 mm) and 46 without a pancreatic lesion. Sixty-two liver metastases (mean size, 10 mm) in 15 patients with pancreatic carcinoma were diagnosed at pathologic examination or multimodality assessment. Three readers blinded to the final diagnosis interpreted all MR (precontrast T1- and T2-weighted and gadoxetic acid-enhanced dynamic and hepatocyte phase MR images) and tetraphasic dynamic contrast-enhanced CT images and graded the presence (or absence) of pancreatic carcinoma and liver metastasis on patient-by-patient and lesion-by-lesion bases. Receiver operating characteristic analysis, McNemar test, and Fisher test were performed to compare the diagnostic performance of CT and MR imaging. RESULTS No significant differences were observed between CT and MR images in depiction of pancreatic carcinoma. However, MR imaging had greater sensitivity in depicting liver metastasis than did CT for two of the three readers in the MR imaging-versus-CT analysis (85% vs 69%, P = .046) and for all three readers in the lesion-by-lesion analysis (92%-94% vs 74%-76%, P = .030-.044). CONCLUSION Gadoxetic acid-enhanced MR imaging was equivalent to dynamic contrast-enhanced CT in depicting pancreatic carcinoma and had better sensitivity for depicting liver metastases, suggesting the usefulness of gadoxetic acid-enhanced MR imaging for evaluation of patients with pancreatic carcinoma.

Dynamic CT for detecting small hepatocellular carcinoma: usefulness of delayed phase imaging.

OBJECTIVE The purpose of this retrospective study was to determine the usefulness of delayed phase imaging for detecting small (< or = 2 cm) hepatocellular carcinomas (HCCs) in patients with liver cirrhosis. MATERIALS AND METHODS Triphasic (arterial, portal venous, and delayed phases) dynamic CT was performed in 33 patients with 48 HCCs proven histopathologically and in 65 control subjects. Arterial, portal venous, and delayed phase images were obtained 30 seconds, 68-70 seconds, and 5 minutes after the start of contrast material injection, respectively. Three blinded observers reviewed the images independently and evaluated tumor attenuation. Diagnostic performance for the combination of phases was assessed using receiver operating characteristic (ROC) curve analysis. RESULTS On arterial phase images, 28 of the 48 HCCs were hyperattenuating, nine were isoattenuating, and 11 were hypoattenuating. On portal venous phase images, three tumors were hyperattenuating, 17 were isoattenuating, and 28 were hypoattenuating. On delayed phase images, five tumors were isoattenuating, and 43 were hypoattenuating. The mean sensitivity for the combination of arterial and portal venous phase imaging was 86.8%, that for the combination of arterial and delayed phase imaging was 90.3%, and that for the combination of all three phase imaging was 93.8%. The area underneath composite ROC curve (A(Z)) for the combination of all three phase imaging (A(Z) = 0.940) was significantly higher than that for the combination of arterial and portal venous phase imaging (A(Z) = 0.917) and for the combination of arterial and delayed phase imaging (A(Z) = 0.922). CONCLUSION Delayed phase imaging is useful for detecting small HCCs and should be included in dynamic CT examinations of patients with liver cirrhosis.