Enhancement In Arterial Phase Research Articles

Pediatric Liver Masses: Radiologic-Pathologic Correlation Part 1. Benign Tumors

Benign hepatic tumors in children include lesions that are unique to the pediatric age group and others that are more common in adults. Infantile hemangioendothelioma, or infantile hepatic hemangioma, is a benign vascular tumor that may cause serious clinical complications. It is composed of vascular channels lined by endothelial cells. At imaging, large feeding arteries and draining veins and early, intense, peripheral nodular enhancement with centripetal filling on delayed images are characteristic features. Mesenchymal hamartoma of the liver occurs in young children and is characterized pathologically by mesenchymal proliferation with fluid-containing cysts of varying size and number. The mesenchymal component or cystic component may predominate; this predominance determines the imaging appearance of the tumor. Benign epithelial tumors that are common in adults may infrequently occur in childhood. These include focal nodular hyperplasia (FNH), hepatocellular adenoma, and nodular regenerative hyperplasia. All are composed of hyperplastic hepatocytes similar to surrounding liver parenchyma and may be difficult to discern at imaging. Preferential hepatic arterial phase enhancement helps distinguish FNH and hepatic adenoma from uninvolved liver. Hepatic adenoma often has intracellular fat and a propensity for intratumoral hemorrhage, neither of which are seen in FNH. Unlike adenoma, FNH often contains enough Kupffer cells to show uptake at sulfur colloid scintigraphy. Nodular regenerative hyperplasia is often associated with portal hypertension, which may be evident at imaging. Knowledge of how the pathologic features of these tumors affect their imaging appearances helps radiologists offer an appropriate differential diagnosis and management plan.

“Flow‐void” sign at MR imaging: A rare finding of extracranial head and neck schwannomas

The authors present two cases of extracranial head and neck schwannomas that exhibited the "flow-void" sign at MR imaging. In the described cases, MR images showed intratumoral signal voids, which corresponded to dilated vessels. Dynamic contrast-enhanced CT also demonstrated dilated vessels within the tumors on the arterial phase and tumor parenchymal enhancement on the delayed phase. Histopathologic examinations of excised specimens revealed thin-walled, dilated abnormal vessels with or without hyaline degeneration. Schwannoma should be considered when MR images demonstrate the "flow-void" sign in extracranial head and neck tumors.

Pancreatic Adenocarcinoma Tumor Grade Determination Using Contrast-Enhanced Magnetic Resonance Imaging

To determine whether the degree of enhancement of pancreatic adenocarcinoma visualized on arterial phase gadolinium-enhanced magnetic resonance imaging (MRI) correlates with the histopathological tumor grade. Thirty-nine patients with pancreatic adenocarcinoma had MRI within 14 days before tumor resection. Gadolinium-chelate-enhanced (Gd) 3-dimensional gradient echo images were acquired including the arterial phase. Tumor imaging patterns on the arterial phase images were classified for low, moderate, or high degree of enhancement and compared against conventional histological grading. Based on histological grading, there were 12 poorly differentiated, 2 poorly to moderately differentiated, 22 moderately differentiated, and 3 well-differentiated adenocarcinomas. There was agreement between the MRI arterial enhancement pattern and histological grading in 30 of 39 cases. The mean size of tumors grouped by enhancement pattern or grade was not significantly different between groups. Although minor discordance was found in 9 of the 39 cases, statistical analysis showed agreement between the degree of arterial enhancement on MRI and histological tumor differentiation; the Cohen's kappa value was 0.64 with a 95% confidence interval of 0.46-0.83. Pancreatic adenocarcinoma arterial phase enhancement correlates with the histological grade of differentiation.

Simultaneous Treatment of Unresectable Hepatocelluar Carcinoma and Hepatic Artery Aneurysm, Case Report

Hepatic artery aneurysm is uncommon with an estimated incidence of less than 0.25%. Because most patients are asymptomatic, the diagnosis is usually made as an incidental finding on imaging studies performed for other reasons. Because of their propensity to rupture with potential catastrophic intraperitoneal hemorrhage, early diagnosis is important. Herein, relatively asymptomatic aneurysm of the common hepatic artery mostly of atherosclerotic etiology is presented. The importance of imaging findings in the diagnosis of this condition is discussed and relevant literature is reviewed (1, 2). Hepatocellular carcinoma (HCC) ranks among the most common malignancies worldwide, and the prognosis for patients with HCC is typically poor. Chemoembolization has become the mainstay of treatment for patients with unresectable HCC. Transcatheter arterial chemoembolization is intended to deliver a highly concentrated dose of chemotherapy to tumor cells, prolong the contact time between the chemotherapeutic agents and the cancer cells, and minimize systemic toxicity. Ideally, achieving these goals will result in a tumor shrinkage, symptomatic relief, improved quality of life, and increased patient survival (3). We will present a case of male patient, 72 years old, who was referred for transcatheter arterial chemoembolization for unresectable hepatocelluar carcinoma. Helical CT scan showed right lobe mass infiltrating the peritoneum with enhancement in the early arterial phase together with hepatic artery aneurysm that was successfully treated at the same time using emulsion of N-butyl cyanoacylate and lipodol with a concentration of 1:1. Hepatic artery aneurysms are uncommon lesions that have varied clinical presentations. Early diagnosis is essential because the natural tendency of the lesion is to rupture into peritoneal cavity or surrounding organs. Chemoembolization has become the mainstay of treatment for patients with unresectable HCC. Our case is notable, because atherosclerotic aneurysms of the hepatic artery are extremely rare with very few cases reported so far and to diagnose a hepatic artery aneurysm and to treat it in one setting with chemoembolization of unresectable HCC without rupture of the aneurysm is also unusual.

Real-time contrast-enhanced ultrasonography of resected and immunohistochemically proven hepatic angiomyolipomas

The purpose of this study was to assess real-time contrast-enhanced ultrasound in patients with hepatic angiomyolipomas with respect to contrast-enhancing kinetics and enhancement patterns. Nonlinear, low mechanical index (mechanical index less than 0.2), real-time contrast-enhanced ultrasonography was performed in 18 patients with 19 tumors after 2.4 mL bolus injection of contrast agent SonoVue. All the 19 tumors were surgically resected and immunohistochemically proven sporadic hepatic angiomyolipomas. Inhomogeneous hyperenhancing pattern was detected 16 tumors (84.2%) and homogeneous hyperenhancing pattern in 1 tumor (0.5%) in arterial phase and portal phase, 16 lesions remained hyperenhancement but one lesion became isoenhancement in late phase. Two lesions (10.5%) were detected inhomogeneously hypoenhancement compared to liver parenchyma during arterial, portal, and late phases, with only punctiform internal enhancement. The margin of all the lesions were smooth and well defined on contrast-enhanced ultrasonography, whereas no peripheral nodular arterial enhancement, centripetal filling, or spoke-wheel like enhancement pattern were depicted. Early strong enhancement in arterial phase, rapid washout of contrast agent, and appear hypoechoic to surrounding liver tissue during portal or late phase was not at all observed. Real-time contrast-enhanced ultrasonography can demonstrate typical imaging characteristics of hepatic angiomyolipomas in most cases, that is, inhomogeneous hyperenhancing pattern in arterial phase, prolonged hyperenhancement during portal and late phase with smooth and well-defined margin. This real-time dynamic imaging technique may therefore improve noninvasive characterization and differentiation of this rare, benign, hepatic mesenchymal neoplasm.

Clinicopathological Analysis of CT Findings of Solid Pseudopapillary Tumor in the Pancreas: A Report of 24 Cases

Objective: To characterize the multi-slice spiral computed tomographic (MSCT) findings and clinicopathology of solid pseudopapillary tumor (SPT) in the pancreas.Methods: The MSCT images of 24 patients with pathologically and immunohistochemically identified SPTs were reviewed.Tumor location, size, contour, boundary, enhancement patterns, degree of enhancement, percentage of necrosis, and calcification of the tumors were observed.The invasion to the adjacent organs and structures and lymph node metastases were analyzed.Results: (1) Of the 24 patients whose MSCT scan images were reviewed, 10 had SPTs in the head of the pancreas, 7 in the body of the pancreas, 6 in the tail of the pancreas, and 1 bestride the body and the tail of the pancreas.(2) There were solid and cystic structures within the neoplasms.The cystic portions appeared hypo-attenuation on both pre-and post-contrast views.The solid portions demonstrated hypo-or iso-attenuation on pre-contrast MSCT scans, slight or midrange enhancement in the arterial phase and marked enhancement in the portal venous phase on post-contrast MSCT scans.The maximal density con- trast beween the solid portions and the pancreatic tissues could be observed in the arterial phase.(3) Six lesions were mainly composed of cystic structures and their solid portions under the capsule appeared as mural nodules.Eight lesions were mainly composed of solid structures with cystic portions near or under the capsule, and 10 lesions were composed of similar proportions of cystic and solid parts distributed alternatively. (4) Eight lesions had calcification within the tumors, 6 lesions were accompanied with associated dilatation of the pancreatic duct, and 1 lesion was accompanied with dilatation of the common bile duct and intrahepatic bile ducts.(5) Nine tumors had malignant tendency, one of which displayed diffused growth.Five lesions were circumvoluted with the blood vessels of the spleen, 2 tumors adhered to the blood vessels of the mesentery, and 1 tumor was circumvoluted with the vena renalis dextra.Other tumors with complete capsules and without invasion to the adjacent organs and structures were diagnosed as benign.There were a few differences between the surgical findings and MSCT scans.Conclusion: The MSCT of SPTs has distinct features and is helpful for the prediction of the malignant risk of SPTs in the pancreas.

Découverte fortuite d’un nodule hépatique de 3 cm à l’échographie chez une femme de 45 ans (sous traitement substitutif hormonal après hystérectomie pour cancer du col de l’utérus)

Incidental liver nodules are more and more frequently encountered because of increasing sensitivity of recent imaging techniques. The identification of biliary cyst or hemangioma is usually easy. In other cases, the etiological diagnosis relies on careful radiological analysis of the pattern of the arterial phase enhancement following contrast medium injection. When there is no early arterial enhancement, a liver biopsy is usually indicated to establish the diagnosis. A strong arterial contrast enhancement pattern is indicative of hepatocellular tumor, benign or malignant. In this situation, it is crucial to establish if there is underlying liver fibrosis. In case of cirrhosis, the diagnosis of hepatocellular carcinoma is the most probable. If the non tumorous liver is normal, focal nodular hyperplasia and hepatocellular adenoma should be differentiated. The distinction between these two tumors is important because only hepatic adenoma carries a significant risk of complications (bleeding or hepatocellular carcinoma) leading to surgical resection of lesions that do not regress after steroid withdrawal. Contrast enhanced MRI and contrast ultrasound are most useful tools for the diagnosis of nodular regenerative hyperplasia but liver biopsy can be necessary in atypical forms. In recent years, the understanding of molecular mechanisms associated with adenoma occurrence allowed for the proposal of a new classification already of practical interest in the management of patients.

Value of multi-slice spiral CT in diagnosis of malignant gastrointestinal stromal tumors

The aim of this study was to investigate the value of multi-slice spiral CT (MSCT) in the diagnosis of malignant gastrointestinal stromal tumors (GISTs). Twenty-seven cases of MSCT images of malignant GIST proved by surgery and pathology were retrospectively analyzed. Both plain and enhanced CT scan was performed and multiplanar reconstruction was made in all cases. The lesions originated from the stomach (n = 11), small intestine (n = 9), colon (n = 4), rectum (n = 1), and mesentery (n = 2). The transverse diameters of mass were 4.2–22 cm, the edges clearly (n = 12), unclearly (n = 15). The mass were mainly irregular in shape lobulated (n = 19). The lesions were mainly heterogeneity on plain scan, moderate to marked enhancement in arterial phase and durative enhanced in venous phase. Cystic necrosis were observed in all the lesions, 9 cases were cystic and solid mixed mass. Hepatic metastases (n = 4), pulmonary metastasis (n = 1), lymphatic metastasis (n = 2) were detected. The accuracy rate of MSCT diagnosis for location and pathologic features of GISTs were 85.2% (23/27) and 77.8% (21/27). Two-phase MSCT examination and axial images combined with multiplanar reconstruction images have important value for diagnosis of malignant GIST.

Contrast-enhanced ultrasonography in nodular splenomegaly associated with type B Niemann–Pick disease: an atypical hemangioma enhancement pattern

Introduction Niemann–Pick disease (NPD) types A and B are lipid storage disorders. NPD type A is a fatal disorder of infancy. Type B is a non-neuronopathic form observed in children and adults. It is associated with enlargement of the liver, spleen, or both, and nodular splenomegaly may be detected with ultrasound. Methods A 21-year-old female was admitted to the Emergency Room with fever, pharyngitis, and left upper quadrant abdominal pain. Labwork revealed anemia, thrombocytopenia, increased levels of AST, ALT, GGT, AF, LDH, triglycerides, and total cholesterol and low levels of HDL-cholesterol. PCR blood assays for CMV and EBV were both negative. Chest X-ray was unremarkable. Transabdominal B-mode ultrasound (US) revealed splenomegaly (long axis: >22 cm), an irregular subcapsular hypoechoic lesion in the superior pole that was consistent with splenic infarction, and multiple round highly echogenic nodes measuring 1–5 cm in diameter. Contrast-enhanced ultrasonography (CEUS) was performed using SonoVue ® (Bracco). Results The presence of a splenic infarction was confirmed. The nodular lesions showed arterial-phase enhancement with late parenchymal phase wash-out. 18F-FDG-PET revealed splenic nodular uptake. Primary splenic lymphoma was suspected, and the patient underwent open splenectomy. The diagnosis was type B NPD with splenic hemangiomas. Discussion CEUS confirmed the diagnosis and extent of splenic infarction, but the nodular atypical enhancement pattern together with nodular 18F-FDG-PET uptake was misleading, suggesting as it did lymphoproliferative involvement of the spleen.

CT response assessment combining reduction in size and arterial enhancement correlates with time to progression in metastatic renal cancer patients treated with TKIs

e16062 Background: Targeted therapy is now the standard of care in advanced Renal Carcinoma (RCC). Response assessment by RECIST criteria is insensitive as treated tumours often have only a modest change in size despite the induction of significant necrosis and does not correlate with time to progression (TTP). The Choi criteria (10% size reduction or 15% contrast enhancement reduction) are routinely used in the assessment of GIST tumours treated with targeted agents. We report the use of combined size and density assessment in RCC metastases treated with either sunitinib or cediranib. Methods: CT scans from 32 patients with metastatic RCC treated with either sunitinib (18) or cediranib (14) were assessed. Scans from 10 patients were not evaluable as non-contrast enhanced scans were performed due to impaired renal function. Scans from a further 2 patients were excluded as they ceased treatment due to toxicity rather than progression. Scans from 20 evaluable patients at baseline and 12 weeks on treatment were assessed using RECIST, Choi, and modified criteria in which both a 10% decrease in size and 15% decrease in enhancement in the arterial phase were required to define a response (PR). A total of 60 lesions were assessed. Response assessment was performed using each of the three methods and correlated with time to disease progression (itself RECIST defined). Statistical analysis was performed using the Mann-Whitney U test. Results: There was no difference in TTP between RECIST defined PR (346.8 days) and SD (328.5 days) (P=0.965). TTP in Choi defined PR (358.4 days) and SD (189.6 days) groups showed improved but non-significant separation of TTP duration (P=0.266). TTP in PR (421.5 days) and SD (200.3 days) groups defined by a combined assessment of reduction in size and enhancement showed greatly improved separation (P=0.064). Conclusions: A combined reduction in both size and arterial phase enhancement of RCC metastases treated with TKIs correlates with time to progression. RECIST and standard Choi criteria appear inferior. No significant financial relationships to disclose.

Diagnosis of solid-pseudopapillary tumor of the pancreas and the value of post-processing in the surgery by spiral CT

To study the CT manifestations of the solid-pseudopapillary tumor of the pancreas (SPTP) and to explore the value of post-processing in the surgery. Clinical and CT features of 14 patients with SPTP proved pathologically were retrospectively analyzed. (1) 13 tumors were composed of different proportions of solid and cystic parts and 1 tumor was composed of solid part only. The solid portions demonstrated slight enhancement in the arterial phase and marked enhancement in the portal venous phase on post-contrast CT. The cystic portions appeared hypo-attenuation on both pre- and post-contrast CT images. Tumors were encapsulated and the capsule enhanced markedly with well-defined margins on post-contrast images. (2) Dilatation of the common bile duct or pancreatic duct wasn't seen in all of the cases and 1 case with the right adrenal ganglioneuroma. (3) 5 tumors located in the head of the pancreas, 3 of which with the superior mesenteric vein compression and displacement, in 2 cases the vessels were partially encapsulated by tumor. 6 tumors located in the tail of the pancreas, 3 of them with splenic hilum compression and multiple splenic vein tortuosity and dilatation, the veins drained into superior mesenteric vein anteriorly and posteriorly of the tumor. Splenic vein compression and posterior displacement occurred in 2 cases. In one case, there was no clear margin between the tumor and the splenic hilum. The SPTP has characteristic CT findings and correct diagnosis could be made by combining clinical features. The relationship of the lesions and surrounding structures could be revealed by the post-processing and was helpful for the operation.

A case of well‐differentiated cholangiolocellular carcinoma visualized with contrast‐enhanced ultrasonography using Sonazoid

We here report the first case of cholangiolocellular carcinoma (CoCC) visualized with contrast-enhanced ultrasonography (CEUS) using a second-generation contrast agent, Sonazoid. A 76-year-old man was admitted to our hospital for evaluation of a hepatic tumor. The tumor was described as having hyper-enhancement in the early phase and persistent enhancement in the late phase by contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI), as well as hypervascularity by angiography. CEUS assessment of the nodule showed diffuse and homogeneous enhancement in the pure arterial phase, which became progressively hypoechoic relative to the adjacent liver parenchyma during the portal vein and late phases (mixed vascular phase), and showed a contrast defect with an unclear border in the Kupffer phase. Histologically we diagnosed this hepatic tumor as CoCC. In light of the above findings and the rarity of CoCC, it is helpful to incorporate the results of several imagings, such as CT, MRI, angiography and CEUS with a second-generation contrast agent when clinically diagnosing CoCC.

Hepatocellular carcinoma in the absence of liver cirrhosis in a treated hepatitis C virus patient.

To the Editor: A 65-year-old male patient was referred to King Faisal Hospital and Research Centre after he presented with jaundice, fever, abdominal discomfort and biochemical evidence of chronic hepatitis C virus (HCV) hepatitis with no clinical or histological evidence of cirrhosis. HCV polymerase chain reaction (PCR) was positive and HCV quantitation was 4682 copies/mL. Liver function test (LFT) results were ALT 225 IU/L (reference range, 5-60 IU/L), AST 104 IU/L (reference range, 5-43 IU/L), total bilirubin 20 μml/L (reference range, 5.1-17.0 μmol/L), INR 1.2 (reference range, 0.9-1.1), and albumin 38 g/L (reference range, 35-50 g/L). Liver biopsy showed chronic hepatitis grade II, stage II portal fibrosis and no evidence of cirrhosis. Alpha-fetoprotein was 6 μgm/L. The patient completed a full year of combination therapy of pegulated interferon 3 million units subcutaneously 3 times/week with ribavirin 1000 mg orally daily and achieved a negative viral PCR with normal LFTs. He had 3 years of follow-up with a sustained virological response (sustained loss of detectable virus in response to antiviral therapy) and was then discharged from our clinic and instructed to follow-up at his local hospital. A CT scan at discharge showed no evidence of cancer (image not available). Two years later he was referred back from his local hospital with a huge right hypochondrial mass associated with pain but no jaundice, fever or weight loss. The mass was about 10 cm in diameter, difficult to separate from the liver, ill-defined, lobulated and hard. Basic tests, including CBC and renal profile were normal. ALT 27 IU/L (reference range, 5-60 IU/L), AST 35 IU/L (reference range, 5-43 IU/L), ALP 75 IU/L (reference range, 30-120 IU/L), total bilirubin 14 μml/L (reference range, 5.1-17.0 μmol/L), INR 1.0 (reference range, 0.9-1.1), and albumin 42 g/L (reference range, 35-50 g/L). AFP was 2.3 μgm/L and carcinoembryonic antigen (CEA) was 2.1 μgm/L. Ultrasound of the abdomen showed a huge liver mass (8cm×11cm) and the right portal vein branch was not visualized distally. CT of the abdomen showed the same mass at segment 5 and 8 which was consistent with hepatocellullar carcinoma (HCC) showing the classical triphasic pattern, i.e., heterogenous enhancement in the arterial phase, but early rapid washout in the portal-venous phase leaving the HCC lesion hypo-dense compared to the surrounding normal tissue (Figure 1). The patient underwent surgical removal of both segments (5 and 8). Histopathology of the mass confirmed the diagnosis of HCC. H&E stain showed the HCC pseudoglandular and trabecular pattern (Figure 2) and extensive lymphovasculer invasion. Immunohistochemical stain for CD34 was positive and showed wrapping of the tumor cluster by endothelial cells. The rest of the non-neoplastic livers showed only mild steatosis and no cirrhosis at all (Trichrome stain) (Figure 3).

Enhancement patterns of pancreatic adenocarcinoma on conventional dynamic multi-detector row CT: Correlation with angiogenesis and fibrosis

To evaluate retrospectively the correlation between enhancement patterns on dynamic computed tomography (CT) and angiogenesis and fibrosis in pancreatic adenocarcinoma. Twenty-three patients with pancreatic adenocarcinoma underwent dynamic CT and tumor resection. In addition to the absolute and relative enhanced value that was calculated by subtracting the attenuation value on pre-contrast from those on contrast-enhanced CT in each phase, we defined one parameter, "tumor-aorta enhancement ratio", which was calculated by dividing enhancement of pancreatic cancer by enhancement of abdominal aorta in each phase. These enhancement patterns were correlated with the level of vascular endothelial growth factor (VEGF), microvessel density (MVD), and extent of fibrosis. The absolute enhanced value in the arterial phase correlated with the level of VEGF and MVD (P = 0.047, P = 0.001). The relative enhanced value in arterial phase and tumor-aorta enhancement ratio (arterial) correlated with MVD (P = 0.003, P = 0.022). Tumor-aorta enhancement ratio (arterial) correlated negatively with the extent of fibrosis (P = 0.004). The tumors with greater MVD and higher expression of VEGF tended to show high enhancement in the arterial dominant phase. On the other hand, the tumors with a larger amount of fibrosis showed a negative correlation with the grade of enhancement during the arterial phase. Enhancement patterns on dynamic CT correlated with angiogenesis and may be modified by the extent of fibrosis.

Enhancement and safety of iomeprol-400 and iodixanol-320 in patients undergoing abdominal multidetector CT

The purpose of this study was to compare iomeprol-400 and iodixanol-320 for contrast enhancement and safety in patients undergoing liver multidetector CT (MDCT). 183 patients undergoing MDCT received equi-iodine (40 gI) iomeprol-400 (n = 91) or iodixanol-320 (n = 92) IV at 4 ml s(-1). Two off-site, independent, blinded readers determined the contrast density (in Hounsfield units (HUs)) in the abdominal aorta, inferior vena cava, portal vein and liver parenchyma during the arterial and portal phases. The mean contrast densities achieved were compared and 95% confidence intervals (CIs) estimated. Heart rate was measured at baseline and at post-dose peak, and a full safety assessment was performed. Study group demographics were comparable. Iomeprol-400 produced significantly greater enhancement of the aorta during the arterial phase (Reader 1: 337.3 HU vs 294.9 HU, 95% CI of difference (19.4, 65.5), p = 0.0004; Reader 2: 325.7 HU vs 295.3 HU, 95% CI of difference (6.6, 54.3), p = 0.01) and greater enhancement of the liver parenchyma during the portal venous phase (Reader 1: 115.1 H vs 108.6 HU, 95% CI of difference (0.27, 12.7), p = 0.04; Reader 2: 115.2 H vs 109.3 HU, 95% CI of difference (-0.1, 11.8), p = 0.05). Similar enhancement of the inferior vena cava and portal vein was noted. Comparably negligible increases in the mean heart rate were observed. Adverse events occurred in 1/91 (1.1%) subjects after iomeprol-400 and 4/92 (4.3%) subjects after iodixanol-320. In conclusion, iomeprol-400 produces greater arterial and portal phase enhancement and has a similarly negligible impact on heart rate and safety.

Unusual Benign Focal Liver Lesions

This presentation aims to provide an overview of the manifestations of some unusual benign focal liver lesions (FLLs) on low-acoustic power contrast-enhanced sonography (CES) with a sulfur hexafluoride contrast agent. The patients were selected retrospectively from 2209 cases with FLLs who had undergone CES examinations for characterization during the past 3 years. The pathologic examinations proved that they were intrahepatic biliary cystadenoma (n = 1), angiomyolipoma (AML; n = 4), lipoma (n = 1), biliary epithelial dysplasia (n = 1), a fungal inflammatory mass (n = 1), tuberculoma (n = 2), an inflammatory pseudotumor (n = 7), sarcoidosis (n = 1), solitary necrotic nodules (n = 2), peliosis hepatis (n = 2), and focal fibrosis after surgery (n = 4). Contrast-enhanced sonography was beneficial in leading to a diagnosis of benignity for some lesions showing hyperenhancement during the arterial phase and sustained enhancement during the portal or late phase, such as liver AML and lipoma. The benign nature of other lesions showing no enhancement during all phases, such as solitary necrotic nodules and focal fibrosis, was also suggestible. On the other hand, for those lesions showing hyperenhancement, isoenhancement, or hypoenhancement during the arterial phase and hypoenhancement during the late phase, including intrahepatic biliary cystadenoma, biliary epithelial dysplasia, infected liver diseases, the inflammatory pseudotumor, sarcoidosis, and peliosis hepatis, the differential diagnosis between benignity and malignancy was difficult, and pathologic tests were mandatory. The CES features of unusual benign FLLs may enrich knowledge when performing CES examinations for characterization and may provide clues for a specific diagnosis of an individual lesion such as liver AML.

Focal Nodular Hyperplasia and Hepatic Adenoma: Differentiation with Low-Mechanical-Index Contrast-Enhanced Sonography

The purpose of our study was to determine the differentiating features of focal nodular hyperplasia (FNH) and hepatic adenoma on contrast-enhanced sonography. Sixty-two patients who underwent contrast-enhanced sonography and were confirmed to have FNH (n = 43) or hepatic adenoma (n = 19) were assessed retrospectively for arterial phase enhancement, filling direction, stellate arteries, and portal phase enhancement. An algorithm was applied to these interpreted features to determine the contrast-enhanced sonography diagnosis. All lesions were hypervascular in the arterial phase. Centrifugal filling was more common in FNH (39 and 32 of 43, 91% and 74% [reader 1 and reader 2]) than in adenoma (3 and 3 of 19, 16%). Centripetal or mixed filling was more common in adenoma (16 and 16 of 19, 84%) than in FNH (4 and 11 of 43, 9% and 26%) (p < 0.001, kappa = 0.61). Stellate arteries characterized FNH (29 and 26 of 43, 67% and 60%) but not adenoma (3 and 2 of 19, 16% and 11%) (p < 0.001, kappa = 0.36). Sustained portal phase enhancement was more common in FNH (37 and 39 of 43, 86% and 91%) than in adenoma (9 and 12 of 19, 47% and 63%) (p < 0.02, kappa = 0.79). The sensitivity, specificity, positive predictive value, and negative predictive value of sonography for diagnosing FNH were 95% and 86%, 74% and 79%, 89% and 90%, and 88% and 71%, (reader 1 and reader 2, respectively). FNH is predicted on the basis of arterial phase centrifugal filling and stellate vascularity on contrast-enhanced sonography. Adenoma is less reliably predicted on the basis of centripetal or mixed filling without stellate vascularity. Sustained portal phase enhancement is more common in FNH than in adenoma but contributes less to the differentiation of these lesions.

Inflammatory pseudotumor of the kidney with renal artery penetration

Inflammatory pseudotumor (IPT) is a quasineoplastic lesion that most commonly involves the lung and the orbit; kidney involvement is rare. We report a case of inflammatory pseudotumor of the kidney. The patient was a 61-year-old man who presented with no symptoms. Nonenhanced computed tomography (CT) demonstrated an ill-defined, isodensity mass measuring 3.5 cm in the lower portion of the left kidney. Contrast-enhanced CT showed that branches of the renal artery without encasement penetrated the tumor; there was a little enhancement in the mass on the arterial phase and homogeneous enhancement on the venous phase. On magnetic resonance imaging the mass showed intermediate signal intensity on T1-weighted images (T1WIs) and low signal intensity on T2WIs. Most IPTs of the kidney appear as an ill-defined, hypovascular, homogeneous tumor on CT images, with variable signal intensity on MRI T1WIs and low signal intensity on T2WIs. Our case had the same imaging findings, with branches of the renal artery penetrating the tumor. If the renal tumor has these radiological findings, the tumor may be IPT.

A Comparison of the Efficacy and Safety of Iopamidol-370 and Iodixanol-320 in Patients Undergoing Multidetector-Row Computed Tomography

To prospectively compare the effects on heart rate (HR) and contrast enhancement efficacy of iopamidol-370 and iodixanol-320 in contrast-enhanced, multidetector-row computed tomography (CE-MDCT). IMPACT is a multicenter, double-blind study involving 166 patients undergoing CE-MDCT of the liver (n = 121) or peripheral arteries (n = 45) randomized to receive equi-iodine doses (40 gI) of iopamidol-370 or iodixanol-320 intravenous at 4 mL/s. CE-MDCT was performed using 16-MDCT scanners according to predefined imaging protocols. HR was measured with the patient in the supine position before and continuously for 5 minutes after contrast medium administration. Mean and peak increases in HR and the proportion of subjects with predefined HR increases (>5 to <10, 10 to <15, 15 to <20, >20 bpm) were compared in the 2 populations. Liver images were assessed by 2 independent, blinded readers for contrast enhancement [Hounsfield unit (HU)], using predefined regions-of-interest during the arterial and portal-venous phase of enhancement. Effects on HR: Eighty-four subjects received iopamidol-370 whereas 82 received iodixanol-320. Mean age, gender distribution, weight, total iodine dose, dose/body weight, concomitant medications and use of beta-blockers were comparable in the 2 groups. Mean baseline HR was similar in the 2 groups (iopamidol-370: 72.3 +/- 12.5 bpm; iodixanol-320: 74.5 +/- 11.9 bpm). Mean changes from baseline to peak postdose were similar in the 2 groups (8.0 +/- 9.3 bpm after iopamidol-370 and 8.4 +/- 14.7 after iodixanol-320, P = 0.72). The proportion of subjects in each group having increases of <5, >5 to <10, 10 to <15, 15 to <20, or >20 bpm was comparable (P = 0.87). Two subjects experienced postcontrast tachycardia (HR increase >70 bpm, peak HR of 146 and 164 bpm), both in the iodixanol-320 group (2.4%). Contrast Enhancement: Of the 121 patients undergoing liver CT, 60 received iopamidol-370 whereas 61 received iodixanol-320. Mean age, gender distribution, weight, total iodine dose, and dose/body weight were comparable in the 2 groups. Iopamidol-370 provided significantly higher HU values in abdominal aorta during the arterial phase of enhancement for both readers [R1: 301.3 +/- 80.2 vs. 273.6 +/- 65.9 HU, 95% confidence interval (6.1-56.8), P = 0.02; R2: 302.0 +/- 73.6 vs. 275.1 +/- 62.9 HU, 95% confidence interval (2.3-51.3), P = 0.03]. No significant difference was observed between the 2 contrast medium during the portal venous phase of enhancement. When the same injection rate and iodine dose is used, the effects on HR of bolus intravenous injections of iopamidol-370 and iodixanol-320 were similar. Iopamidol-370 provides significantly greater enhancement during the arterial phase and similar enhancement during the portal venous phase compared with iodixanol-320.

Enhancement Patterns of Hepatocellular Carcinoma at Contrast-enhanced US: Comparison with Histologic Differentiation

To retrospectively compare the arterial and portal venous phase enhancement patterns of hepatocellular carcinoma (HCC) at contrast material-enhanced ultrasonography (US) with the degree of HCC histologic differentiation. This study was approved by the research ethics board, and informed consent was obtained. The study population included 112 consecutive patients (91 men, 21 women; aged 25-86 years) with 112 histologically proved HCCs: 23 well differentiated, 77 moderately differentiated, and 12 poorly differentiated. All underwent continuous real-time low-mechanical-index contrast-enhanced US from wash-in of contrast material to 300 seconds by using a blood-pool microbubble agent. Initial image interpretation included arterial enhancement, dysmorphic intratumor arteries, and presence and time of negative enhancement (washout). Enhancement patterns were compared with histologic differentiation by using the Fisher exact test. In the arterial phase, 97 of 112 (87%) HCCs showed hypervascularity, with a significantly higher proportion in moderately differentiated HCCs (74 of 77, 96%) when compared with well- (14 of 23, 61%; P<.001) and poorly differentiated HCC (nine of 12, 75%; P<.004). Eight of 112 (7%) were isovascular and seven (6%) were hypovascular. Dysmorphic arteries were seen in 81 (72%) HCCs. Of 97 hypervascular tumors, only 42 (43%) showed typical washout by 90 seconds. Late washout appeared in 25 (26%) HCCs in the 91-180 seconds phase and in 21 (22%) in the 181-300 seconds phase. The remaining nine showed no washout up to 300 seconds and seven (78%) were well-differentiated HCCs. Moderately differentiated HCC generally shows classic enhancement features, while well- and poorly differentiated tumors account for most atypical variations. Extended observation in the portal phase is important as late washout occurs with slightly more frequency than washout in the conventionally defined portal venous phase.