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In the absence of vitamin K (VK) or in the presence of VK antagonists, hepatic VK-dependent carboxylase activity is inhibited and des-gamma-carboxyprothrombin (DCP) is released into the blood. We analyzed the number of glutamic acid (Glu) residues and their positions in the Gla domain (GD) of DCP to investigate the gamma-carboxylation mechanism of VK-dependent carboxylase. Several DCPs were found in each subject studied. The 10 Gla residues of human prothrombin were carboxylated in order from the N-terminal (residues 26, 25, 16, 29, 20, 19, 14, 32, 7 and 6). The process of Glu carboxylation seemed to proceed three-dimensionally from inside to outside the molecule.

Purpose: To determine whether the frequency of hepatocellular carcinoma (HCC) in patients with cirrhosis is affected by hepatic iron deposition as detected with magnetic resonance (MR) imaging., Materials and Methods: In a retrospective search of MR imaging and histopathology records, 196 patients with histopathologically proved cirrhosis and with (n = 80) or without (n = 116) HCC who underwent T2-weighted conventional or fast spin-echo and gradient-echo (GRE) (echo time > or = 6.0 msec) imaging were identified. MR images were qualitatively and quantitatively evaluated for diffuse hepatic iron deposition and siderotic regenerative nodules to assess their correlation with the presence of HCC., Results: Hepatic parenchymal iron deposition was seen in 79 (40%) patients, and iron deposition in regenerative nodules was seen in 71 (36%) at MR imaging. The mean signal intensity ratio of GRE images in patients with hepatic iron deposition was significantly lower than that in patients without it (P < .001). The frequency of HCC in patients with iron deposition in regenerative nodules (52% [37 of 71 patients]) was significantly higher (P = .015) than that in patients without iron in regenerative nodules (34% [43 of 125 patients])., Conclusion: The occurrence of HCC may be associated causally with iron deposition in regenerative nodules in patients with cirrhosis. MR imaging can enable detection of iron deposition in regenerative nodules as a possible risk factor for the development of HCC.

The purpose of our study was to compare T2-weighted breath-hold fast spin-echo sequence (BHFSE) and high-resolution dynamic MR imaging (HR-DMRI) in the detection of hepatocellular carcinoma (HCC). Short and long T2-weighted BHFSE sequences and biphasic HR-DMRI including arterial-dominant and delayed phase images with a phased-array body coil were performed in 30 consecutive patients with 37 HCCs. The lesion-to-liver contrast-to-noise ratio (CNR) was quantitatively measured. The lesion conspicuity and delineation was qualitatively rated according to a four-point scale. The lesion-to-liver CNR was highest with the arterial-dominant phase HR-DMRI and was significantly higher than those obtained with both short and long T2-weighted BHFSE and those obtained with unenhanced and delayed HR-DMRI. The CNR obtained with short T2-weighted BHFSE was significantly higher than those obtained with long T2-weighted BHFSE and with unenhanced and delayed HR-DMRI. The sensitivity for the sequences was 78.4% (29/37) for short T2-weighted BHFSE, 67.6% (25/37) for long T2-weighted BHFSE, 37.8% (14/37) for unenhanced HR-DMRI, 97.3% (36/37) for arterial-dominant phase HR-DMRI, and 43.2% (16/37) for delayed HR-DMRI. The sensitivity of serial dynamic MR imaging combined with unenhanced, arterial-dominant phase imaging and delayed phase imaging was 100% (37/37). The score in the qualitative analysis of the lesion conspicuity and delineation was highest for the arterial-dominant phase HR-DMRI and was significantly higher than that for the short T2-weighted BHFSE. The score for the short T2-weighted BHFSE was significantly higher than that for the long T2-weighted BHFSE and that for the unenhanced HR-DMRI. Arterial-dominant phase HR-DMRI is superior to the T2-weighted BHFSE technique, and also HR-DMRI combined with unenhanced, arterial-dominant and delayed phases is the most sensitive technique in the detection of HCC.

Background: T1- and T2-weighted magnetic resonance (MR) images frequently show fan-shaped areas of hypo- or hyperintensity in the hepatic parenchyma adjacent to a treated hepatocellular carcinoma after percutaneous ethanol injection (PEI) therapy. These areas correspond to abnormal contrast enhancement on serial dynamic MR images. The purpose of the present study was to describe the location, appearance, and frequency of these abnormalities because it is important to understand these entities for the correct assessment of therapeutic efficacy., Methods: MR imaging including a multisection dynamic study was performed in 20 consecutive patients with hepatocellular carcinoma treated with PEI therapy. We retrospectively evaluated the presence of fan-shaped hypointensities adjacent to treated tumors in the liver parenchyma on T1-weighted images and hyperintensities on T2-weighted images and corresponding fan-shaped contrast enhancement on both arterial-dominant and delayed-phase dynamic MR images. We review the location, appearance, and frequency of these findings, and we discuss the possible causes on the basis of pathologic examinations., Results: Seven (35%) of the 20 patients showed fan-shaped hyperintense areas adjacent to the treated tumors on T2-weighted images. These areas showed isointensity in five patients and hypointensity in two patients on T1-weighted images. Of these seven patients, one (14%) underwent the MR imaging within 1 month after the completion of PEI therapy, and six (86%) had it 2-9 months after the completion of PEI therapy (mean = 6 months). In all seven patients, fan-shaped hyperperfusion abnormalities corresponding to these areas of hyperintensity on T2-weighted images were seen on both arterial-dominant and delayed-phase dynamic MR images. Pathologically, the coagulative necrosis of the hepatocytes with sinusoidal dilatation and the restoration by the development of fibrous tissue were seen in these fan-shaped areas., Conclusion: The fan-shaped areas of abnormal intensity on T1- and T2-weighted images and contrast enhancement on dynamic MR images seem to be attributable to pathologic changes in the normal liver parenchyma induced by the toxic reaction of ethanol. Awareness of the occurrence of such abnormalities in the peripheral liver parenchyma adjacent to the treated tumor is important for the correct assessment of therapeutic efficacy.

Hepatic lesions with delayed enhancement are sometimes encountered on gadolinium-enhanced MRI of the liver. This study illustrates the varied appearances of several pathologic entities with delayed enhancement, including hepatic hemangioma, hepatic metastases, intrahepatic cholangiocarcinoma, focal nodular hyperplasia, hepatic abscess, hepatocellular carcinoma, and hepatocellular carcinoma after transcatheter arterial chemoembolization, and presents the utility of arterial-phase dynamic MRI in the differential diagnosis of these lesions. Possible causes of these delayed enhancements are also discussed.

For patients with small hepatocellular carcinomas (HCCs) treated by percutaneous ethanol injection (PEI) therapy, dynamic MRI has been performed to evaluate the therapeutic efficacy at our institute. In this pictorial essay, we illustrate the various dynamic MR findings of HCCs after PEI therapy, including complete necrosis, partial necrosis, local recurrence, and pathologic conditions such as arterioportal shunt and contractive changes of hepatic parenchyma. We also present the limitation of dynamic MRI in the evaluation of therapeutic effectiveness of PEI therapy.

Background: The goal of this study was to investigate the frequency of inhomogeneous parenchymal enhancement of the liver in magnetic resonance imaging during arterial portography (MRAP) versus computed tomography during arterial portography (CTAP)., Methods: CTAP and MRAP were performed in 29 and in 21 patients, respectively, who had suspected primary or secondary liver tumors on clinical or biological grounds. We evaluated the frequency of inhomogeneous hepatic parenchymal enhancement not related to a decrease of portal blood supply due to compression or obstruction by the tumor and physiologic variation in portal perfusion. Inhomogeneous parenchymal enhancement of the liver was classified as segmental or subsegmental and as nonsegmental., Results: Segmental or subsegmental inhomogeneous parenchymal enhancement was seen in six of 29 patients (20.1%) on CTAP and in one of 21 patients (4.8%) on MRAP. Nonsegmental inhomogeneous parenchymal enhancement was seen in five of 29 patients (17.2%) on CTAP images and in none of the patients (0%) on MRAP images. The incidence of nonsegmental inhomogeneous parenchymal enhancement was significantly lower on MRAP than on CTAP., Conclusion: MRAP was superior to CTAP in achieving homogeneous parenchymal enhancement of the liver.

High spatial resolution dynamic magnetic resonance (MR) imaging performed with a phased-array body coil is a useful tool for evaluating hepatocellular carcinoma. The examination consists of fast spin-echo T1- and T2-weighted images obtained in a single breath hold; multisection, dynamic, fast gradient-echo images obtained in a single breath hold; and contrast material-enhanced images obtained in the arterial-dominant and delayed phases. Hepatocellular carcinoma, with its predominantly arterial blood supply, usually appears hyperintense on arterial-dominant phase images and isointense or hypointense relative to liver parenchyma on delayed-phase images. Hepatocellular carcinomas, especially those larger than 1.5 cm, contain a fibrous capsule or an inner septum, which allows them to be differentiated from other tumors. These characteristics are particularly important in the diagnosis of hypovascular hepatocellular carcinomas, which do not have an arterial blood supply and thus do not enhance. Extracapsular invasion, a relatively common finding in advanced cases, is seen as a nodular enhancing area that projects into the surrounding liver parenchyma adjacent to the main tumor on arterial-dominant phase images and as an iso- or hypointense area on delayed-phase images. Portal vein invasion appears as an obstruction of the vein, and portal vein tumor thrombi appear as intermediate-signal-intensity masses. The technique can also be helpful in the follow-up of treatment.

Objective: In the arterial phase of dynamic contrast-enhanced MR images, we observed areas of increased contrast enhancement adjacent to hepatocellular carcinomas treated by percutaneous ethanol injection. The purpose of this study was to assess the frequency, appearance, and location of this hyperperfusion abnormality. It is important not to mistake this finding for other pathologic conditions., Subjects and Methods: Multisection dynamic MR images obtained in 33 consecutive patients with hepatocellular carcinoma treated with percutaneous ethanol injection were reviewed. Hepatic parenchymal hyperperfusion abnormalities were diagnosed when areas of early enhancement were seen in the hepatic parenchyma adjacent to the treated tumor. The location, appearance, and frequency of the findings were recorded., Results: Hepatic parenchymal hyperperfusion abnormalities were observed in 15 (45%) of the 33 patients on arterial-dominant-phase images. Of these 15 patients, 10 (67%) had MR imaging within 1 month after percutaneous ethanol injection. Hyperperfusion abnormalities were located in liver parenchyma adjacent to the lesion with wedge-shaped appearances. In two patients, early opacification of the peripheral portal branch was seen within the area of hyperperfusion abnormalities., Conclusion: Hepatic hyperperfusion abnormalities are commonly seen adjacent to a treated hepatocellular carcinoma on contrast-enhanced MR images. Awareness of this hyperperfusion abnormality, which is caused by increased blood flow after percutaneous ethanol injection, is important because such a finding may be misinterpreted as another pathologic condition such as tumor progression or tumor thrombosis of the portal vein branches.

Objective: Our goal was to evaluate the usefulness of multisection dynamic MRI with gadopentetate dimeglumine in the assessment of the therapeutic efficacy of transcatheter arterial chemoembolization (TAE) with iodized oil for hepatocellular carcinomas (HCCs)., Materials and Methods: Findings on multisection dynamic MRI images were compared with gross appearance and histologic findings in 13 patients with HCCs after TAE with iodized oil. Arterial dominant phase images of the entire liver were obtained 20 s after the start of administration of gadopentetate dimeglumine., Results: In 3 of the 13 patients, no enhancing areas within the tumors were detected. In the remaining 10 patients, enhancing portions were detected within the tumor on arterial dominant phase images. Histologically, viable tumor cells were present in the rapidly enhancing portions, while necrotic tissues were present in nonenhancing areas, irrespective of the accumulation of iodized oil on CT scans. However, in one patient in whom no enhancing portion was seen in the tumor, a small number of viable tumor cells within the capsule were identified on pathologic examination., Conclusion: Multisection dynamic MRI is helpful for evaluating the therapeutic efficacy of TAE with iodized oil for HCCs by revealing the hemodynamics of the tumor irrespective of accumulation of iodized oil.

The breath-hold multislice dynamic study (BMDS) in MRI, which can scan the entire liver during a single breath-holding, was applied to 16 patients with 30 focal lesions of hepatocellular carcinoma (HCC). The BMDS was performed at 20 seconds and 3 minutes after the bolus injection of Gd-DTPA, by gradient echo pulse sequence (FLASH). 29 nodules were detected in the BMDS, showing rapid enhancement on early phase and decline on delayed phase images. The BMDS was more sensitive than conventional MR images. Therefore, the BMDS seems to be useful for the diagnosis of HCC with multiple as well as solitary nodules.