Recent developments in three-dimensional (3D) ultrasound technologies have made it possible to display 3D ultrasound images in real time. 3D ultrasound image data acquired using a mechanical 3D dynamic (4D) probe or a two-dimensional (2D) matrix array probe are resampled and reconstructed to generate 3D ultrasound images. This paper describes the principles and effectiveness of such 3D visualization methods. There are two basic 3D visualization methods: the multiplanar reconstruction/reformation (MPR) method and the rendering method. In the MPR method, any desired cross-sectional plane can be displayed from the 3D data. In the rendering method, the 3D data are displayed to give the appearance of a 3D object projected onto a 2D plane. The volume rendering method is more suitable for 3D ultrasound data. There are two volume rendering methods: the translucent display method and the maximum intensity projection (MIP) method. The translucent display method employs the concept of opacity. It is possible to change the image characteristics by adjusting the opacity curve and the image quality parameters (transparency and threshold). In the rendering method, Doppler mode or the perspective projection method can be used in combination, improving and expanding the visualization capabilities in diagnostic applications. Global illumination has been realized by photon mapping technology. The position of the light source and the effects of indirect lighting are simulated, resulting in extremely realistic 3D display. In order to obtain high-quality 3D images, it is necessary to acquire the 3D ultrasound data under optimal conditions. In volume rendering, the threshold, transparency, and filter settings for image smoothing all affect the image quality. It is important to select the appropriate display method and to set the optimal imaging conditions to obtain the best possible image quality in clinical diagnosis.

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Echocardiography is an essential examination in the diagnosis and treatment of cardiovascular disease as it noninvasively yields much information. In Japan, there has been an estimated increase of 9,000 adults with congenital heart disease every year from 1997 to 2007. In 2007, there were estimated to be about 409,101 adults with congenital heart disease (ACHD) in Japan. An increasing number of those with ACHD face lifestyle-related diseases, pregnancy-related problems, and cardiac dysfunction. However, there are few pediatric cardiologists engaged in the medical treatment of those with ACHD. Therefore, knowledge of echocardiography of ACHD is necessary for physicians and laboratory technicians. Although adults with congenital heart disease share the basic cardiac anatomical anomalies and physiology with the pediatric population, cardiac structures grow and evolve with the patients. Structural changes occur following surgical palliation and repair. Even without intervention during infancy and childhood, progression into adulthood can bring with it changes in ventricular mass, calcification or dysplasia of valves, and myocardial fibrosis. Many of these patients face further operations and interventions. They require lifelong medical care. Echocardiography is an essential tool for the diagnosis and follow-up of adults with congenital heart disease. In adults, it is often difficult to obtain much information with echocardiography, because adults with congenital heart disease have limited acoustic windows. However, it is possible to evaluate the primary form of ACHD by using a segmental approach, where it is possible to grasp the pathological state by identifying the issues involved in each of its states as the examination proceeds. In echocardiography of adults with congenital heart disease, it is important to organize the knowledge of the morphological characteristics of congenital heart disease, natural history, surgical methods, and postoperative history (complications, residuae, sequelae).

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The advent of fetal echocardiography had an enormous impact on the perinatal management of fetuses with congenital heart disease. In addition, accurate prenatal diagnosis and parent counseling provide additional time for them to accept the antepartum baby expected to be born with congenital anomalies. Moreover, prenatal treatment of fetuses with twin-to-twin transfusion syndrome, fetal pleural effusion, or fetal tachyarrhythmia is impossible without an accurate prenatal diagnosis. The focus of this review article is to cover topics ranging from the hemodynamics of fetal circulation to echocardiographic screening of congenital heart disease based on the segmental approach.

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Liver stiffness measurement (LSM) by transient elastography with use of FibroScan is one of the most accurate methods for staging liver fibrosis. LSM can be readily performed by an operator after a short training period. Transient elastography is a promising noninvasive alternative to liver biopsy for detecting hepatic fibrosis. LSM by transient elastography is the most popular method for detecting liver fibrosis stage in the world. Many other factors may also increase liver stiffness such as hepatic infiltration by hepatic inflammatory cells, increased venous pressure, mechanical cholestasis, and amyloidosis. Transient elastography appears to be a clinical useful test for detecting cirrhosis, in particular.

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The long-term prognosis for patients with diffuse liver disease depends on an accurate diagnosis of hepatic fibrosis and assessment and prediction of improvements in this fibrosis with treatment. These assessments are vital for determining the hepatic cancer risk. A histological diagnosis of liver biopsy specimens is regarded as the gold standard for the assessment of hepatic fibrosis; however, noninvasive and accurate assessment methods for hepatic fibrosis are desired because of difficultly with repeated assessments due to the invasiveness and sampling errors encountered with biopsy. Based on platelet count and hepatic fibrosis marker measurements as well as relevant blood tests, formulas for calculating hepatic fibrosis have been tested. A method of assessing hepatic fibrosis using ultrasound was also developed, and its usefulness has been reported. Real-time tissue elastography (RTE) is a technology developed in Japan that can be loaded into commercially available diagnostic equipment. It provides a color display of information on tissue hardness in real time using a fast computation method, Combined Autocorrelation Method (CAM), for relative hardness based on tissue deformation in vivo. RTE enables measurements to be performed simply and noninvasively for the assessment of hepatic fibrosis. Relationships between the degrees or severity of features on RTE images and various stage assessment methods for hepatic fibrosis have been reported, but RTE most favorably reflects fibrosis without the effects of inflammation, cholestasis, or fatty deposition. It also enables serial assessments of improvements in hepatic fibrosis in response to treatment to be performed.

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Background and Aim: We measured liver stiffness (LS) in patients with acute liver disease (ALD) using Virtual touch quantification (VTQ) and investigated the usefulness of measuring LS for predicting the prognosis of ALD patients. Materials and Methods: From April 2010 to December 2012, we evaluated 51 patients with ALD. The subjects included 32 patients with acute hepatitis (AH), 14 patients with acute hepatitis severe form (AH-s), who had no hepatic encephalopathy despite plasma prothrombin time of <40%, and five patients with fulminant hepatitis (FH) diagnosed according to the criteria of the Japanese Study Group. The relationships among velocity of shear wave (Vs), clinical diagnosis, liver function tests, and prognosis were evaluated. Receiver operating characteristic (ROC) analysis was performed to investigate whether VTQ exhibits potential usefulness for the early prediction of FH. In addition, we investigated the relationship between LS and the grade of liver damage using D-galactosamine-induced acute hepatitis in rats. Results: Vs on admission was 2.03 ± 0.55 m/s, 2.54 ± 0.56 m/s, and 3.65 ± 0.86 m/s in the AH, AH-s, and FH groups, respectively. Vs was significantly higher in the FH group than in the other groups (p<0.001). The area under the ROC curve for predicting FH was 0.893 (sensitivity 80.0, specificity 93.5). Vs was significantly increased in the non-survivors (n=4), while it decreased in survivors (n=47) (p=0.003). Vs by grade of liver damage was G0: 1.07 ± 0.05 m/s, G1: 1.27 ± 0.09 m/s, G2: 1.54 ± 0.23 m/s, and G3: 1.99 ± 0.16 m/s. Vs increased significantly with the severity of hepatic inflammation and necrosis (p<0.01). Conclusion: Vs measured by VTQ reflects the severity of liver damage, and the serial changes in Vs predict the prognosis of ALD patients. Vs is an early and precise biomarker of FH.

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It is known that if the speckle signals in liver parenchyma are assumed to be uniform, the probability density function (PDF) of echo signals can be approximated using the Rayleigh distribution. The increase of structures such as fibers and fat as liver disease progresses causes the PDF to deviate from the Rayleigh distribution. Acoustic structure quantification (ASQ) is a technique to quantify the degree of deviation from the Rayleigh distribution. In other words, ASQ is a method of quantifying crudeness of liver parenchyma echo scans, and its applications in diagnosing liver fibrosis and liver fatty metamorphosis have been reported. The degree of deviation from the Rayleigh distribution is calculated as the ratio of mean dispersion within the region of interest (ROI) to Rayleigh distribution dispersion values (Cm²). It has been reported that there is a correlation between Cm² values and liver fibrosis, with the Cm² values rising significantly as fibrosis progresses. Furthermore, it has been reported that a parameter, focal disturbance-ratio (FD-ratio), which assesses the non-uniformity of local areas in the liver using ASQ, is useful when diagnosing liver fatty metamorphosis, under the condition of which the FD-ratio decreases as liver fat increases. In contrast to elastography, which is used to quantitatively evaluate the stiffness of the liver, ASQ is a means of quantifying the crudeness of liver parenchyma, and its further development as a new method for quantifying diffuse liver disease is anticipated.

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The liver differs from other organs in that it receives a dual blood supply from the hepatic portal vein and hepatic artery. The portal vein, which delivers nutrients and various other substances to hepatocytes, accounts for approximately 70-80% of the total hepatic blood supply. The remaining 20-30% is supplied via the hepatic artery and mainly nourishes the biliary system. Compared with a blood pressure of ＞ 100 mmHg in the hepatic artery, the pressure in the portal vein is as low as 6-8 mmHg, making the latter system susceptible to pathological changes in the liver. Despite being safeguarded by two blood supplies, when infected, for example by the hepatitis C virus, the liver undergoes cycles of necrosis, defluxion, and fibrosis. As the disease state progresses from chronic hepatitis to cirrhosis, the blood flow in the portal vein is reduced, and as if to compensate for this, the arterial blood flow increases. In other words, the hepatic hemodynamic balance between the portal vein and hepatic artery changes from portal vein dominant to hepatic artery dominant. Diagnostic imaging modalities able to quantitate the changes in the hemodynamic balance of the liver are clinically valuable because they enable noninvasive staging of hepatitis C and can be used to predict the timing of interferon treatment or the onset of complications. We have been using arrival time parametric imaging to examine the hemodynamics of the nutrient hepatic blood flow to improve our understanding of the pathological manifestations of liver diseases. Here, we introduce the latest developments in this area.

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Purpose: Atrophy of the internal segment of the left hepatic lobe (S4) has been reported as the first morphological change in chronic liver disease. S4 atrophy was evaluated by B-mode ultrasound, and the results were compared with liver fibrosis index estimated by FibroScan (FS). Material and Method: Fifty-two cases with hepatitis C were examined with abdominal ultrasonography and FS on the same day that they were enrolled. S4 atrophy was evaluated by the distance between the transverse portion of the portal vein and the edge of the S4 (S4 distance). Liver fibrosis was determined as the median of the stiffness on FS as the gold standard. The correlation between S4 distance and stiffness, each blood test date, and spleen index were assessed. Results: The S4 distance became longer with progression of liver fibrosis, i.e., 4.0, 4.2, 7.6, 7.9, and 9.5 mm (mean) for F0, F1, F2, F3, and F4, respectively. There were significant differences between F0 and F2, F0 and F3, F0 and F4, F1 and F2, F1 and F3, and F1 and F4. At a cut-off value of 5.6 mm, it was possible to distinguish F2 or higher with a sensitivity of 91.3% and a specificity of 80.0%. There was a significant correlation between the S4 distance and each blood test data, but not the spleen index. Conclusion: Our findings suggested that S4 distance could serve as a new index for easily and objectively staging hepatic fibrosis. In particular, it was a clinically useful tool in that it could detect fibrosis ≥F2.

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Cystic adventitial disease of the popliteal artery is a rare cause of lower extremity occlusive disease. Lower leg pain is usually a sign of vessel disease and cystic adventitial disease is rarely considered. However, ultrasound examinations can very easily and quickly detect such cysts. Including an ultrasound examination in the work-up is therefore recommended in patients with acute lower leg pain. We report two cases where an ultrasound examination was useful in detecting this rare disease. Case 1: a 56-year-old male, ankle brachial index at rest dropping from 1.10 to 0.58 in 3 months with spontaneous disappearance of a cystic mass occurring 4 weeks later. Case 2: a 52-year-old male successfully treated with surgery.

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