Doppler ultrasound is widely used in clinical settings for measurement of blood flow dynamics and tissue motion. The continuous-wave Doppler method enables measurement of very fast blood flow such as that caused by heart valve occlusion, while it lacks spatial resolution. In measurement of blood flow, ultrasonic echoes from blood cells are much weaker than those from slowly moving tissues such as the heart wall. Therefore, a filter, i.e., clutter filter, is required to suppress echoes from slowly moving tissues. The pulsed-wave Doppler method enables measurement of blood flow or tissue motion in a specific region assigned by a so-called “range gate”. However, maximum measurable velocity is determined by the aliasing effect. The aliasing phenomenon is also explained in this paper. Color Doppler ultrasound estimates velocity of a target using the autocorrelation technique, and it can visualize two- or three-dimensional distribution of blood flow or tissue velocity. This paper provides brief explanations on the basic principles for measurement of blood and tissue velocities based on the Doppler ultrasound.

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Echocardiographic strain imaging, known as deformation imaging, has been developed as a means to objectively quantify regional and global myocardial function. Strain can be obtained with tissue Doppler imaging or with 2D speckle tracking. Strain imaging has been used to gain greater understanding into the pathophysiology of ischemic heart disease, dyssynchrony, cardiomyopathies, the effects of valvular disease on myocardial function even at the subclinical stage, and diastolic heart failure. Strain imaging has also been used for the evaluation of cardiotoxicity to detect left ventricular (LV) dysfunction prior to fall in LV ejection fraction in patients undergoing chemotherapy. Strain imaging can be used to assess right ventricular and left atrial function. Further advances, such as 3D speckle tracking strain imaging, have emerged to provide even greater insight. Strain imaging is still undergoing development, and further clinical studies are required to determine if clinical decisions based on strain imaging result in better outcomes. With this important limitation in mind, strain may have great potential to play many roles in clinical practice.

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In recent years, incidental thyroid tumors detected by imaging studies such as ultrasonography, CT, MR, and PET are increasing in number. It is necessary to perform ultrasonography and fine-needle aspiration cytology in order to diagnose thyroid tumors. The most important aspect of ultrasonic diagnosis is to make the differential diagnosis of malignant tumors from benign tumors. However, fine-needle aspiration cytology is generally regarded to be unnecessary in cases of small and benign tumors detected on ultrasonography. It is important to detect malignant tumors, especially papillary carcinomas, on ultrasonography. Most papillary carcinomas present typical and malignant findings on ultrasonography. Papillary microcarcinomas (<=10 mm) are classified as either high risk or low risk by ultrasonography in our hospital. The result of observation without immediate surgery (or “active surveillance”) for patients with papillary microcarcinomas in the low-risk group proved to be satisfactory in terms of clinical management. Most patients with benign tumors should be observed without surgery during clinical management. Physicians at general hospitals must decide at what point during clinical management to refer patients with thyroid tumors to a facility specializing in thyroid diseases.

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Point-of-care ultrasound is now widely recognized in clinical settings as a tool that allows symptom or sign-based examination during the diagnosis of critical conditions. As this ultrasound technique is useful for judging physiological conditions very quickly in a real-time fashion, the authors have coined the term “ABCD sonography” for this technique, and they have been conducting educational workshops across Japan. The concept of ABCD sonography is reviewed in this manuscript.

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Transperineal ultrasound (TPU) started to be used in the 1970-80s for assisting biopsies of the prostate. Only in the mid to late 1990s did it become a tool used by both urogynecologists and obstetricians. Different from invasive urodynamic tests, and digital vaginal or digital rectal examination, this approach is noninvasive and well tolerated by patients. While MRI or CT examination requires expensive equipment and highly trained personnel, TPU is easy to perform and can be done in real time to answer the clinical question being investigated. Furthermore, cine loop clips are easily acquired and stored for later evaluation and for educational purposes. In urogynecology, TPU can be used to visualize the urethra and its hypermobility, being useful for diagnosis of stress urinary incontinence. During labor, TPU allows an objective assessment of fetal head descent in the birth canal. Many other measurements have been proposed by different scientists: the angle of progression, the head direction, the progression distance, and the head-perineum distance. The angle of progression is the most widely used parameter. TPU is also used to assess fetal head rotation, with both 2D and 3D images. The latter helps with the visualization of fetal sagittal suture in real time. It is clear that with all these potentialities, TPU can become the most objective way to help in making a key decision at time of delivery: perform an operative vaginal or potentially difficult cesarean delivery. In postpartum, TPU can be used to visualize the rectal sphincter, and it is being used to identify patients at high risk for fecal incontinence. Nowadays, TPU is becoming the most advanced and objective tool used in many labor and delivery units around the world during the first and second stage of labor to assess fetal position and fetal station, and in puerperium to visualize the rectal sphincter.

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Translabial ultrasound in the second stage of labor can be complementary to vaginal examination for evaluation of fetal descent and rotation. Furthermore, it can contribute to an easy and successful instrumental delivery, because we can evaluate the probability and safety of these procedures and can estimate the direction of extraction.

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Speckle tracking is a non-Doppler, angle-independent method that enables the measurement of myocardial velocity and deformation using frame-by-frame tracking of bright myocardial areas, often termed “kernels”. With the advent of this non-Doppler technology, data on velocity, strain, and strain rate of cardiac ventricles during the fetal period have been accumulated. Of importance, speckle tracking analysis provided new insights into regional as well as global myocardial motion. With its application to “sick fetuses”, speckle tracking has potential impact on in utero assessment of fetal cardiac function leading to the optimal perinatal management.

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Dual gate Doppler analysis is one of the most useful methods developed in recent years. This technology allows us to assess two different regions of interest simultaneously. It facilitates the diagnosis of fetal arrhythmia. Furthermore, two different techniques, such as pulsed wave Doppler and tissue Doppler imaging, can be employed simultaneously. We hope dual gate Doppler analysis will allow us to investigate fetal circulation and/ or fetal condition.

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The ultrasonic ‘phased tracking method’ (PTM) is a newly developed technique in which we can observe the phase difference of adjoining received RF signals. We aim to apply PTM—which enables precise measurement of the target’s velocity with 0.1 mm/s accuracy without restriction of transmitting wave length—for noninvasive measurements of fetal arterial diameter change, pulse wave velocity (PWV), and estimated fetal pulse pressure. We analyzed normal and growth-restricted fetuses using PTM. The fetal descending aorta was identified in the long axis direction using conventional B-mode with a convex array probe. Raw radiofrequency signals were recorded from the vessel wall of the descending aorta. Offline analysis was attempted for wall motion velocity waves. We employed PTM for measurement of pulsatile fine movement of the fetal descending aorta. Changes in internal diameter and PWV were analyzed. Pulse pressure was estimated from the transformed formula of Moens-Korteweg. PWVs were revealed to be significantly higher in growth-restricted fetuses. We could also demonstrate elevated estimated fetal pulse pressure in growth restriction. Measurement of fetal aortic diameter changes and fetal PWV using PTM is a feasible, noninvasive approach to evaluate fetal hemodynamics. Elevated PWV and estimated pulse pressure in growth-restricted fetuses suggest altered arterial wall compliance by histological remodeling that has already originated in the fetal period. Fetal PWV and estimated pulse pressure possibly distinguish cases at high risk for hypertensive complications later in life, which substantiates Developmental Origins of Health and Disease (DOHaD) theory.

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The present paper describes the usefulness of high-definition real-time ultrasound (HDlive) imaging, which is a new volume rendering mode in obstetrics. Since an adjustable light source facilitates the ability to create lighting and shadowing effects, increasing depth perception provides extraordinarily realistic imaging of the fetus. Sonographic images made by HDlive look almost like actual photographs taken by fetoscope.

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We report a case of flat-infiltrating gallbladder cancer with massive liver invasion. A 64-year-old man was referred to our hospital because a liver mass was detected by medical checkup. A liver mass 45 mm in diameter was shown next to the gallbladder by abdominal computed tomography (CT) and magnetic resonance imaging (MRI), but no remarkable elevated lesion in the gallbladder was shown by these images. Wall thickening and wall abnormality of the gallbladder were also not found. Based on these findings, we suspected intrahepatic cholangiocellular carcinoma (CCC) or liver abscess. Abdominal ultrasonography (US) showed a hyperechoic heterogeneous mass adjacent to the gallbladder. This finding was incompatible with liver abscess. US using a high-frequency probe visualized localized gallbladder wall thickening and continuity of the wall thickening with the liver mass. Contrast-enhanced US (CEUS) revealed hyper-enhancement of the liver mass and gallbladder wall thickening in the arterial phase. Ring enhancement was then shown around the liver mass. The liver mass was depicted as a contrast defect in the post-vascular phase. Based on the CEUS findings, gallbladder cancer was suspected rather than CCC. The final diagnosis was gallbladder cancer with liver invasion, for which surgical resection was performed. Histopathological study revealed that the liver tumor was a poorly to moderately differentiated adenocarcinoma. In the gallbladder, adenocarcinoma cells had spread widely, compatible with flat-infiltrating gallbladder cancer. In conclusion, US using a high-frequency probe would be a very useful to confirm the relation between liver tumors near the gallbladder and the wall of the gallbladder. And CEUS will be helpful to diagnose liver tumors adjacent to the gallbladder.

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Cytomegalovirus (CMV) infection is the most common intrauterine infection worldwide, and the clinical manifestations are potentially severe. Typically, the diagnosis of acute CMV infection in pregnancy is based on positive results for maternal IgM. Herein, we present a case of a fetal CMV infection in which maternal CMV-specific IgM antibodies were negative. The patient was a 29-year-old primipara. At 24 weeks’ gestation, fetal ascites, growth restriction (-2.3 SD), and a hyperechoic bowel were detected by ultrasound scan. Fetal anemia was strongly suspected based on the markedly elevated fetal middle cerebral artery peak systolic velocity value at 84.6 cm/s (2.5 MoM). We performed umbilical cord sampling; fetal anemia was mild, but marked thrombocytopenia was noted (hemoglobin level: 9.2 g/dL, platelet count: 28,000/mm³). Maternal blood tests for IgM against TORCH revealed negative results. Nevertheless, we strongly suspected congenital CMV infection based on the sonographic and cord blood examination findings. PCR using amniotic fluid drained at 25 weeks and 3 days revealed CMV-DNA, at which point a definitive diagnosis of congenital CMV infection was made. The condition of the fetus deteriorated, and at 26 weeks and 2 days, fetal death was noted. Pathological examination of the placenta after stillbirth revealed CMV placentitis. This case suggests that maternal CMV-specific IgM antibodies are not reliable for excluding CMV infection in cases of fetal infection with characteristic sonographic findings.

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This is the first case report of breast myeloid sarcoma showing vascularity changes using contrast-enhanced ultrasonography with Sonazoid^®. The pretreatment ultrasonography showed an ill-defined hypoechogenic mass with heterogeneity containing severely hypoechoic areas. The contrast-enhanced ultrasonography illustrated a diffuse hypervascular mass. Based on the diagnosis of acute myeloid leukemia and breast myeloid sarcoma , the patient received remission induction therapy. Two months after the treatment, ultrasonography identified a slight reduction in the size of the severely hypoechoic lesion with no apparent change in global tumor size. The contrast-enhanced ultrasonography demonstrated a generally hypovascular mass, which was well correlated with fibrotic changes in general with only a small tumor mass remaining. We conclude that contrast-enhanced ultrasonography is valuable for assessing treatment effect in breast myeloid sarcoma.

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