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Ultrasonography (US) is the first-line diagnostic tool for observing the whole abdomen. Unfortunately, a wide spectrum of refraction-related artefactual images is very frequently encountered in routine US examinations. In addition, most practitioners currently perform abdominal US examinations without sufficient knowledge of refraction artifacts (RAs). This review article was designed to present many representative RA images seen in the clinical setting, with a brief explanation of the mechanism of these images, in certain cases through an analyzed and reconstructed method using computer simulation that supports clinical observations. RAs are encountered not only with B-mode US but also with Doppler US, contrast-enhanced US, and shear wave elastography. RAs change their appearance according to the situation, but they always have a significant effect on detailed interpretation of abdominal US images. Correct diagnosis of abdominal US relies on a deep understanding of each characteristic artifactual finding, which necessitates knowledge of basic US physics. When analyzing mass lesions, computer simulation analysis helps to reveal the global images of RAs around a lesion., (© 2021. The Japan Society of Ultrasonics in Medicine.) more...

Introduction: Hereditary hemorrhagic telangiectasia (HHT) is a multiorgan genetic angiodysplastic affection characterized by visceral vascular malformations. It affects mainly the brains, lungs, gastrointestinal tract, and nasal mucosa. Unlike those organs, hepatic involvement, although very frequently occurring, is insufficiently recognized, mainly because of the complex vascular structure of this organ. Thus, treating HHT patients requires a solid understanding of these hepatic anomalies. It is especially important for any general clinicians to be able to recognize clinical findings in HHT, which leads to a high suspicion of HHT and have an index of suspicion for liver abnormalities of HHT. For this purpose, keen awareness of clinical as well as hepatic sonographic (US) findings is paramount., Aim: The aim of this review is to summarize previously reported findings on the hepatic US through a thorough analysis of related articles, and to (a) determine the role of US in the diagnosis of hepatic involvement in HHT patients and (b) propose the most simple and easy way to detect HHT-related abnormalities during routine US examinations., Conclusion: Hepatic US serves to diagnose the detailed complex hepatic changes typical of HHT, and contributes to increased diagnostic confidence of hepatic changes in HHT patients, with the most simple way not to overlook HHT-related abnormalities being to find hepatic artery dilatation. more...

Purpose: Hepatocellular carcinoma (HCC) on normal liver is very rare. The goal of this study was to determine the clinical manifestations and the role of ultrasonography (US) in the diagnosis of HCC arising in normal liver., Methods: The clinical data and US findings in 12 cases of surgically resected HCC in normal liver were retrospectively analyzed., Results: The patients were asymptomatic, had no hepatocarcinogenic factor, and hepatic function tests were almost normal in most cases. HCCs were large, encapsulated, and solitary, and there were predominantly well-differentiated or moderately differentiated in most cases. US showed a hypoechoic rim and lateral shadowing, suggestive of peritumoral capsule formation, and on contrast-enhanced US (CEUS), the tumor was hyperenhanced in arterial phase and washed out in postvascular phase, revealing typical HCC findings., Conclusions: US raises suspicion of HCC by showing lateral shadowing on grayscale ultrasound and hypervascularity on CEUS of the lesion., (© 2018 Wiley Periodicals, Inc.) 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...

Background: "Searchlight phenomenon" is an ultrasound artifact that appears as thin, bright, and posteriorly extending lines in the gallbladder lumen. It mimicks the comet-tail artifact, but it does not decrease in intensity in the depth of the view field, unlike the comet-tail artifact., Purpose: To determine the mechanism of this unpublished ultrasound artifact on the basis of clinical ultrasound images as well as using an in vitro system., Materials and Methods: (1) CLINICAL STUDY: to determine the detection rate of the searchlight phenomenon in 453 subjects with a normal abdominal US examination result according to the medical chart. We also analyzed the appearance of the searchlight phenomenon in which US showed the searchlight phenomenon in the gallbladder. (2) Basic study: we placed a thin (thickness: 12 μm) polyethylene membrane at the depth of 2.5 cm from the transducer inside a water bath. Then, we inserted air bubbles (50-400 μm) below the membrane and observed when the ring-down artifact and searchlight phenomenon appeared., Results: (1) CLINICAL STUDY: the searchlight phenomenon was observed in 30 out of 453 (6.6 %) subjects. When the searchlight phenomenon was seen, duodenal gas was present dorsally in the same line of sight, and the searchlight phenomenon appeared only when duodenal gas was accompanied by the ring-down artifact on US. (2) Basic study: a stepwise increase in the number of air bubbles gave rise to (a) multiple echo spots (single layer of air bubbles), (b) ring-down artifact (two layers), and (c) ring-down artifact below the membrane and searchlight phenomenon in front of the membrane simultaneously. The ring-down artifact and searchlight phenomenon always appeared in the same line of sight., Conclusion: The searchlight phenomenon is thought to be a range-ambiguity artifact of the ring-down artifact. Duodenal gas is thought to give rise to this artifact. When examining the gallbladder with ultrasound, knowledge of many artifacts including the searchlight phenomenon can prevent us from making a hazardous misdiagnosis. more...