Search

Range-ambiguity artifacts (RAAs) are an erroneous mapping of returning echoes into a composite picture. The purpose of this review was to illustrate the mechanism of RAAs and to present the diagnostic problems caused by RAAs. RAA features differ slightly from organ to organ. At the level of the urinary bladder, RAAs take the form of a cloud-like, ill-demarcated, immobile, echogenic area, and the depth of the echogenic area differs depending on the pulse repetition frequency (PRF). This form is referred to as "static RAA" in this review. There are two key ultrasound characteristics of RAAs at the level of the liver: (a) the depth of RAAs change according to the PRF, and (b) RAAs move in accordance with the cardiac cycle. This form is referred to as "mobile RAA" in this review. At the level of the gallbladder, RAAs take the form of fine echogenic lines in the gallbladder. This phenomenon is actually a combination of two phenomena: a ring-down artifact and RAA. This form is referred to as "complex RAA (searchlight phenomenon)" in this review. The easiest way to reduce RAAs is to change the image depth. Sufficient knowledge of RAAs can prevent misdiagnosis of erroneously displayed returning echoes as real pathologic changes. more...

Focal nodular hyperplasia (FNH) is the second most common benign tumor of the liver, and diagnosis and follow-up without invasive procedures are now highly recommended. FNH shows a characteristic vascular structure called "spoke-wheel appearance". However, this appearance relies on the mode of the feeding artery, and the mode of the draining vein has not been sufficiently studied until recently. Superb microvascular imaging (SMI) is a new Doppler technology designed to improve visualization of the blood flow, especially slow flow signals from fine vessels, using a new algorithm. Thus, we can expect to see an improvement in visualization of fine vessels in FNH using SMI. Here, we present two cases in which SMI clearly demonstrated not only the typical spoke-wheel appearance but also draining to the hepatic veins. Our observation is believed to be noteworthy in the diagnosis of FNH. In conclusion, we have reported two cases of hepatic FNH in which SMI revealed clearly not only its feeding vessels and intratumoral vasculature but also its draining vessels communicating with the hepatic vein. SMI is considered to increase our diagnostic confidence by revealing fine vessels within and around the FNH lesion. more...

Purpose: Contrast-enhanced ultrasound (CEUS) is a very sensitive diagnostic tool in characterizing liver tumors. It is especially useful in the diagnosis of focal nodular hyperplasia (FNH) of the liver. According to the previous reports, FNH is common in young women, and it is usually diagnosed by MRI. The majority of the previous reports come from European countries, and a very few studies of large series designed to describe the clinical features in Japanese patients have been reported. The aim of this study was to (a) describe the clinical features in 53 patients (59 lesions) diagnosed with CEUS and (b) compare the data with those from the previous reports., Methods: The medical data from 53 patients diagnosed on the basis of typical CEUS findings at our institution and affiliated hospitals were reviewed, and their clinical data were analyzed., Results: (1) The medical data from 53 cases showed a slight male predilection, with 30 male cases (57 %) and 23 female cases (43 %), although the occurrence in both sexes was equal. FNH cases were distributed throughout all generations in both sexes, mostly concentrated in the age of 30-60 years old, and metabolic cases were more common in men than in women (4 vs 0). (2) The lesions were small (mean: 23 mm) and distributed throughout the whole liver. (3) Lesion size was not influenced by age in either sex. (4) A rapid draining to the hepatic vein was recognized in five out of 59 lesions (8 %)., Conclusions: Our data indicate that FNH occurs slightly more frequently in men than in women in Japan. It occurs also at any age in both sexes, but the mean lesion size was smaller in our series than in the previous reports. Metabolic disease was seen only in male FNH patients. A direct communication between the FNH lesion and the hepatic vein is diagnostically worth noting. more...

Aim: To identify the hepatic vascular architecture of patients with hepatitis C virus (HCV) using superb microvascular imaging (SMI) and investigate the use of SMI in the evaluation of liver fibrosis., Methods: SMI was performed in 100 HCV patients. SMI images were classified into five types according to the vascular pattern, and these patterns were compared with the fibrosis stage. Moreover, the images were analyzed to examine vascularity by integrating the number of SMI signals in the region of interest ROI [number of vascular trees (VT)]. The number of VT, fibrosis stage, serum parameters of liver function, and CD34 expression were investigated., Results: There was a significant difference between SMI distribution pattern and fibrosis stage (P < 0.001). The mean VT values in each of the fibrosis stages were as follows: 26.69 ± 7.08 in F0, 27.72 ± 9.32 in F1, 36.74 ± 9.23 in F2, 37.36 ± 5.32 in F3, and 58.14 ± 14.08 in F4. The VT showed excellent diagnostic ability for F4 [area under the receiver operator characteristic (AUROC): 0.911]. The VT was significantly correlated with the CD34 labeling index (r = 0.617, P < 0.0001)., Conclusion: SMI permitted the detailed delineation of the vascular architecture in chronic liver disease. SMI appears to be a reliable tool for noninvasively detecting significant fibrosis or cirrhosis in HCV patients. more...

Contrast-enhanced sonography (CEUS) is a very important diagnostic imaging tool in clinical settings. However, it is associated with possible artifacts, such as B-mode US-related artifacts. Sufficient knowledge of US physics and these artifacts is indispensable to avoid the misinterpretation of CEUS images. This review aims to explain the basic physics of CEUS and the associated artifacts and to provide some examples to avoid them. This review includes problems related to the frame rate, scanning modes, and various artifacts encountered in daily CEUS examinations. Artifacts in CEUS can be divided into two groups: (1) B-mode US-related artifacts, which form the background of the CEUS image, and (2) artifacts that are specifically related to the CEUS method. The former includes refraction, reflection, reverberation (multiple reflections), attenuation, mirror image, and range-ambiguity artifacts. In the former case, the knowledge of B-mode US is sufficient to read the displayed artifactual image. Thus, in this group, the most useful artifact avoidance strategy is to use the reference B-mode image, which allows for a simultaneous comparison between the CEUS and B-mode images. In the latter case, CEUS-specific artifacts include microbubble destruction artifacts, prolonged heterogeneous accumulation artifacts, and CEUS-related posterior echo enhancement; these require an understanding of the mechanism of their appearance in CEUS images for correct image interpretation. Thus, in this group, the most useful artifact avoidance strategy is to confirm the phenomenon's instability by changing the examination conditions, including the frequency, depth, and other parameters. [ABSTRACT FROM AUTHOR] more...

Hepatocellular carcinoma (HCC) in a non-fibrotic liver (F0) is considered to be rare, and there is a marked paucity of studies in the literature on this HCC type. A review of the literature shows some important clinical and tumor characteristics: (a) it occurs mainly in young female and elder male patients; (b) clinically, under normal hepatic function, alpha-fetoprotein level is often normal, and there are no risk factors; (c) associated with metabolic disease; (d) macroscopically, single large lesions are noted; and (e) microscopically, the lesions are well-differentiated and encapsulated. Radiological imaging results are straightforward, showing arterial hyperenhancement and later wash-out. The combined use of B-mode and contrast-enhanced (CE) ultrasound (US) is the most reliable and cost-effective diagnostic method. Few peri-and post-operative complications are noted and 5-year survival is not inferior to patients with HCC on fibrosis liver despite the lesion's large size. Most clinicians believe that HCC is unlikely to occur if patients have no symptoms and normal hepatic function. Although detailed clinical data are very limited, we expect that this review will help to improve the clinical management of HCC in non-fibrotic livers. [ABSTRACT FROM AUTHOR] more...

We present three cases of chronic hepatic porphyria (CHP) in alcoholic patients, in which grayscale ultrasound (US) revealed multiple echogenic masses in the liver, mimicking multinodular hepatocellular carcinoma on alcoholic liver injury. In all cases, contrast-enhanced US (CEUS) showed iso-enhancement of the mass lesions throughout all vascular phases. Additionally, two-dimensional shear wave elastography (2DSWE) (performed in two cases) revealed the mass to have almost the same SWE value as the surrounding parenchyma. When encountering alcoholic patients with multiple echogenic masses in the liver, CHP must be included in the differential diagnosis. CEUS and 2DSWE allow us to increase our diagnostic confidence of CHP. [ABSTRACT FROM AUTHOR] more...