Left ventricular (LV) hypertrophy is not uncommonly discovered incidentally on electrocardiograms taken as part of medical checkups. Echocardiography is the safest and most effective examination method for diagnosing it and searching for the cause. The causes of LV hypertrophy are various, including extrinsic factors such as pressure overload and volume overload, genetic factors, and deposition of abnormal substances. Because LV hypertrophy is a predictor of cardiovascular events and prognosis, it is of great clinical importance to assess the degree of LV hypertrophy. LV hypertrophy does not mean only thickening of the LV wall but also an increase in the mass of the entire myocardium due to enlargement of individual myocardial cells. LV hypertrophy is classified into concentric hypertrophy and eccentric hypertrophy according to relative wall thickness and left ventricular mass index (LVMI). LVMI is measured using either the linear method or the tomographic method. The tomographic method is recommended when the LV is morphologically abnormal. Whichever method is used, accurate measurement of the LV wall thickness and lumen is important. It is fundamental to measure them at the correct position and not to mistakenly measure other structures inside the ventricles. The cause of LV hypertrophy is determined based on the degree of the LV wall thickness and its distribution. However, it is difficult to specify the cause of LV hypertrophy based solely on echocardiography, and it is important to make a comprehensive judgment together with family history, physical findings, and various examinations.

At the core of breast ultrasonography is the B-mode examination. B-mode ultrasound is a form of morphological diagnosis in which pathological features are interpreted through ultrasound images composed of the ultrasound signals from objects. Color Doppler ultrasound is a form of vascular imaging, overlapping the color flow mapping formed from the Doppler shift frequency on a B-mode image. Proper equipment settings and examination techniques are essential for successful breast color Doppler examinations, leading to a better ultrasound diagnosis. In contrast-enhanced ultrasonography, ultrasound images are generated from nonlinear responses from microbubbles oscillating at a lower sound pressure, so it is called contrast harmonic imaging. Estimation of histopathology and the subsequent categorization on B-mode ultrasound are at the core of breast ultrasonography. And the addition of flow imaging to B-mode makes it possible to improve the diagnosis on breast ultrasonography so that we can reliably diagnose breast cancer and benign lesions, as well as avoid unnecessary biopsies. In this review article, I will describe the principles of color Doppler ultrasonography and contrast-enhanced ultrasonography, the history of flow imaging in breast ultrasound, the histopathology of vascularity on breast lesions, equipment settings, and examination techniques for Doppler ultrasonography. In addition, I will discuss how to utilize flow imaging in breast ultrasonography in daily practice.

Cervical cystic disease or peritracheal tumors can be difficult to differentiate on ultrasound of the head and neck. Cervical cystic diseases include congenital cystic lesions and tuberculosis. Lymph node metastasis of papillary thyroid carcinoma and human papillomavirus-related oropharyngeal carcinoma should be considered in the differential diagnosis. Appropriate diagnosis and treatment are required because target ages and treatment methods are different. The characteristics of each disease and the tests necessary for differentiation are herein described. Peritracheal mass lesions include various diseases such as thyroid tumors, parathyroid tumors, paratracheal lymph node metastasis, and schwannoma. Since many structures are densely packed in a narrow area, it is often difficult to distinguish them using only ultrasonography. It is necessary to comprehensively judge clinical findings, various imaging examinations, and pathological examinations to make the differential diagnosis. Use of chemoradiotherapy, which is one form of curative treatment for head and neck cancer, is increasing in recent years. Ultrasonography is also useful for evaluating the response to chemoradiotherapy for cervical lymph node metastasis. Degeneration after treatment occurs gradually over 8 to 16 weeks, so it is important to continue monitoring the patient. Reduction in lymph node size, changes in echogenicity, and disappearance of fluid and blood flow components are observed after treatment. Ultrasonography can be used to observe qualitative changes in lymph nodes that cannot be visualized with CT or MRI. By combining ultrasonography with other imaging examinations, it may be possible to assess the response to treatment with higher accuracy.

In recent years, lung ultrasonography has become increasingly popular in the diagnosis of respiratory diseases as part of point-of-care ultrasound (POCUS), especially in the emergency department. Because the lungs contain air and are surrounded by a bony thorax, lung ultrasonography is not useful for all respiratory diseases. Another important feature of lung ultrasonography is the use of various artifacts produced. POCUS is performed by dividing the anterior thoracic region into eight sections. Findings seen in normal subjects include the bat sign, A-line, lung sliding, lung pulse, and seashore sign. It is important to understand these normal findings as their absence indicates the presence of a respiratory disease. Typical respiratory diseases for which lung ultrasonography is useful in the diagnosis include pneumothorax, interstitial pneumonia, and pneumonia. Abnormal findings in each disease include lung point in pneumothorax, multiple B-lines in interstitial pneumonia, and sonographic consolidation in pneumonia. The combination of abnormal findings and lack of normal findings in the patient is used to narrow down the possible differential diseases.

Purpose: Assessment of blood flow is an important function in diagnostic ultrasound imaging. Color flow imaging is one such method widely used in the clinical setting. Since autocorrelation suffers from aliasing, the time interval between successive transmissions of ultrasonic pulses should be as short as possible. For this purpose, a specific transmit-receive sequence, namely, packet transmission, is widely used in color flow imaging. Also, plane wave imaging recently introduced to ultrasound imaging significantly contributes to improvement of the temporal resolution. Furthermore, a singular value decomposition (SVD) clutter filter reportedly outperforms a conventional clutter filter. In the present study, the feasibility of the SVD clutter filter in plane wave imaging with the packet transmission sequence was investigated. Method: In the present study, the packet transmission sequence was implemented in plane wave imaging by sending plane waves multiple times in the same direction before changing the steering angle. In the first strategy, like conventional color flow imaging with line-by-line acquisition using a focused transmit beam, a clutter filter was applied to ultrasonic radiofrequency (RF) signals in each packet. In the second strategy, the number of transmissions per packet was set at two, and a clutter filter was applied to RF signals obtained from the first or second transmission in different packets. Results: The in vivo experimental results on a human carotid artery showed that the second strategy with an SVD filter realized significantly better performance than the first strategy with a polynomial regression filter used as a conventional filter. Conclusion: An SVD clutter filter was feasible in plane wave imaging with the packet transmission sequence, and the performance was improved by limiting the number of transmissions per packet to two.

Purpose: Patients with a Fontan circulation tend to develop liver fibrosis, liver cirrhosis and even hepatocellular carcinoma. A noninvasive ultrasound technique for liver fibrosis and cardiac function assessment in Fontan-associated liver disease (FALD) is needed to evaluate disease progression in real time. This study aimed to evaluate whether hepatic vein (HV) waveform analysis and elastography could be alternative markers to cardiac index (CI) in patients with FALD and assess factors influencing elastography measurements in FALD cases. Methods: All patients underwent cardiac catheterization, B-mode ultrasound and ultrasound elastography measurement. Moreover, we measured serum markers related to fibrosis and examined HV blood flow using duplex Doppler ultrasonography. Results: Forty-three patients (median age, 17 years; interquartile range, 12-25 years; 29 men, 6 with liver biopsy) were enrolled. The real-time tissue elastography (RTE) value was significantly higher in patients who underwent surgery > 7 years prior, suggesting that this value probably reflects the liver fibrosis due to FALD from the early fibrosis stage. The ultrasound elastography did not significantly correlate with hemodynamic parameters. The area under the receiver operating curve for the diagnosis of CI < 2.2 L/min/m2 using HV waveform was superior to the results from elastography and calculated fibrosis indices. Conclusion: HV waveform can be used as a noninvasive measurable surrogate marker for CI. The RTE value increased overtime after the operation and would reflect liver fibrosis. The combination of RTE and HV waveform type could be useful noninvasive tools to evaluate clinical conditions in FALD patients in real time.