The purpose of this study is to clarify the changes of peripheral normal liver parenchyma before and after ethanol injection, with respect to MR appearances and pathologic findings and, in so doing, to clinically evaluate the therapeutic effectiveness of percutaneous ethanol injection (PEI) therapy. The normal liver in 12 rabbits was injected with ethanol. We performed conventional and dynamic MR imaging and prepared the histopathologic specimens 1 week (group 1), 2 weeks (group 2), and 1 month (group 3) after ethanol injection. On conventional MR images, coagulative necrosis in the normal liver was demonstrated as an area of low signal intensity on T1-weighted images and high signal intensity on T2-weighted images in all groups. On dynamic MR images, contrast enhancement in the coagulative necrosis was not seen in groups 1 and 2; however, gradual and concentric enhancement was seen in the direction of the central necrotic portion from early-to-delayed phase image in group 3. Although signal intensity of the coagulative necrotic area in the normal liver after ethanol injection may mimic that of untreated or viable hepatocellular carcinoma (HCC) when clinically encountered on conventional MR images, coagulative necrosis of the normal liver parenchyma will be discriminated from viable HCC by using dynamic MR imaging.

Animals↗

PubMedDate not supplied

Hepatic parenchymal hyperperfusion abnormalities detected with multisection dynamic MR imaging: appearance and interpretation.

On arterial-dominant-phase images in multisection dynamic MR imaging, early-enhancing areas that are perfusion abnormalities rather than tumor deposit are sometimes encountered. The purpose of this article was to determine the frequency, location, and appearance of these hepatic parenchymal hyperperfusion abnormalities and to discuss possible causes of these abnormalities. Multisection dynamic MR images obtained in 415 patients with suspected hepatobiliary diseases were reviewed for the presence of hyperperfusion abnormalities. A total of 96 hyperperfusion abnormalities were identified in 88 (21%) of 415 patients. They were characterised from their shape, distribution, or location as lobar or segmental (n = 36 [38%]), subsegmental (n = 32 [33%]), or subcapsular (n = 28 [29%]) hyperperfusion abnormalities. Presumable etiologies were considered as follows: (a) compression, obstruction, or ligation of the portal vein; (b) siphoning effect by tumor; (c) aberrant cystic venous drainage; (d) percutaneous ethanol injection; (e) percutaneous needle biopsy; (f) rapid drainage by the subcapsular vein; or (g) cirrhosis or unknown. A significant percentage of patients had hepatic hyperperfusion abnormalities. Familiarity with these hyperperfusion abnormalities on multisection dynamic MR images is important to prevent false-positive diagnoses.

Adult↗

PubMedDate not supplied

Takayasu arteritis: MR manifestations and diagnosis of acute and chronic phase.

Diagnosis of Takayasu arteritis is difficult because the clinical features are similar to those of other diseases. In the late occlusive or pulseless phase Takayasu arteritis, angiography usually demonstrates luminal changes such as such as stenosis, occlusion, or aneurysmal dilatation of the aorta and pulmonary artery and of their branches. However, absence of such luminal changes does not exclude the possibility of early or systemic phase Takayasu arteritis. Cross-sectional scanning such as CT scan and MRI plays an important role in demonstrating arterial wall changes in the early diagnosis of Takayasu arteritis. Improvement in the clinical findings and subsidence of the active inflammatory process can be expected with early steroid treatment. The common and uncommon MR appearances of the late occlusive phase and the recently described radiographic features of the early systemic phase are illustrated.

Diagnosis, Differential↗

PubMedDate not supplied

Hepatic parenchymal enhancement in the cirrhotic liver: evaluation by triple-phase dynamic MRI.

BACKGROUND: To evaluate the changes of liver parenchymal enhancement in the cirrhotic liver by means of triple-phase dynamic magnetic resonance (MR) imaging. METHODS: Triple-phase multisection dynamic MR imaging was performed in 32 patients with liver cirrhosis. The control group consisted of 19 patients without liver cirrhosis. After precontrast images were obtained, arterial phase images were acquired 20 s after the start of intravenous bolus administration of 0.10 mmol/kg of gadopentetate dimeglumine. Portal and delayed phase images were then acquired 1 and 3 min, respectively, after the injection of contrast material. On each phase image, the signal-to-noise ratio (S/N) from the liver parenchyma was measured by operator-defined regions of interest (ROIs). The contrast-enhanced ratio (CER) on each phase was then obtained according to the following formula: [S/N(arterial or portal or delayed phase image) - S/N(precontrast image)] / S/N(precontrast image). The portal perfusion index (PPI) also was obtained according to the following formula: [S/N(portal phase image - S/N(arterial phase image)] / S/N(arterial phase image). The results were expressed as mean +/- SD. RESULTS: The CERs of arterial, portal, and delayed phase images in patients with and without liver cirrhosis were 0.256 +/- 0.211, 0.640 +/- 0.384, and 0.554 +/- 0.318 and 0.132 +/- 0.094, 0.404 +/- 0.204, and 0.324 +/- 0.144, respectively. The CERs were highest in the portal phase and lowest in the arterial phase in patients with and without liver cirrhosis. The CER of the cirrhotic liver was significantly higher than that of the normal liver in every phase (p < 0.05). PPIs with and without liver cirrhosis were 2.90 +/- 4.03 and 3.86 +/- 3.89, respectively. The PPI with liver cirrhosis was significantly lower than that without liver cirrhosis (p < 0.05). CONCLUSION: The enhancement of cirrhotic liver parenchyma is greater than that of the normal liver parenchyma at every phase of triple-phase dynamic MR imaging.

Adult↗

PubMedDate not supplied

Homogeneous enhancement of hepatic parenchyma: MR imaging during arterial portography versus CT during arterial portography.

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.

Aged↗

PubMedDate not supplied

Fan-shaped hepatic parenchymal damage after ethanol injection therapy for hepatocellular carcinoma: MRI appearances.

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.

Carcinoma, Hepatocellular↗

PubMedDate not supplied

Hepatic perfusion abnormalities in acute pancreatitis: CT appearance and clinical importance.

BACKGROUND: The purpose of the present study was to describe the computed tomography (CT) appearances of transient hepatic attenuation differences (THADs) in patients with acute pancreatitis and to discuss the mechanism of THAD. METHODS: Two-phase dynamic CT images of 28 patients with acute pancreatitis were reviewed. Among them, THAD was seen in nine patients. All patients underwent ultrasonography, and four patients with THAD underwent surgery. RESULTS: Three types of THAD (THAD adjacent to the gallbladder in five of 28 patients, THAD with left lobar distribution in three of 28, wedge-shaped THAD in one of 28) were seen on the two-phase dynamic CT scans of patients with acute pancreatitis. In five patients, THAD disappeared when acute pancreatitis had subsided. CONCLUSIONS: THAD in acute pancreatitis is probably caused by increased arterial blood flow attributable to the inflamed lobe of the liver or the inflamed gallbladder. THAD in acute pancreatitis should not be confused with primary liver abnormalities.

Acute Disease↗

PubMedDate not supplied

Alkaline and acid phosphatase activities in the gingiva and alveolar bone in scurvy.

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Acid Phosphatase↗

PubMedDate not supplied

Differential diagnosis of hepatic tumors with delayed enhancement at gadolinium-enhanced MRI: a pictorial essay.

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.

Bile Duct Neoplasms↗

PubMedDate not supplied

Distinction of hemangiomas from hepatic tumors with delayed enhancement by incremental dynamic CT.

To analyze the patterns of contrast enhancement and to evaluate clinical utility, we performed table incremental dynamic CT in 21 patients with 30 hepatic hemangiomas and in 12 patients with 26 malignant neoplasms, which showed delayed enhancement. On incremental CT, dense, spotty peripheral enhancement was present in 23 of the 30 (77%) hemangiomas. In contrast, a circumferential bead- or band-like peripheral enhancement was seen in 19 of 26 (73%) malignant neoplasms. The findings were characteristic. We conclude that incremental CT is useful in the differential diagnosis of hepatic hemangioma in routine examination.

Adenoma, Bile Duct↗

PubMedDate not supplied

Therapeutic efficacy of transcatheter arterial chemoembolization for hepatocellular carcinoma: MRI and pathology.

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.

Adult↗

PubMedDate not supplied

Dynamic MR follow-up of small hepatocellular carcinoma after percutaneous ethanol injection therapy.

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.

Aged↗

PubMedDate not supplied

High-resolution contrast-enhanced MRI of the uterus with a phased-array multicoil.

High-resolution contrast-enhanced dynamic MRI of the uterus can be performed with the combination of a phased-array multicoil and fast GE techniques. This technique can improve the ability to visualize normal anatomy of the uterus and periuterine tissues, including vascular structures and pelvic ligaments, and to detect pathologic processes of the uterus and determine their extent.

Adult↗

PubMedDate not supplied

High-resolution dynamic MR imaging of hepatocellular carcinoma with a phased-array body coil.

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.

Carcinoma, Hepatocellular↗