Color flow imaging can be used to visualize blood vessels and measure intratumoral blood velocities. Because it yields functional information such as hemodynamics in addition to B-mode morphological information, it is a very useful function that can contribute greatly to improvement of diagnostic precision. When using color Doppler, optimal equipment settings such as flow rate scale, color Doppler gain, color display area, filter, and Doppler frequency are important.

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Pancreatic lesions are generally classified as solid or cystic lesions. Solid neoplasms include pancreatic ductal carcinoma, neuroendocrine tumor (NET), solid pseudopapillary neoplasm (SPN), and tumor-forming pancreatitis. Cystic neoplasms include serous cystic neoplasm (SCN), mucinous cystic neoplasm (MCN), and intraductal papillary mucinous neoplasm (IPMN). As ultrasound (US) reflects macroscopic pathological findings precisely, we should acknowledge the characteristic structures of each type of pancreatic cystic lesion, such as the honeycomb structure of SCN, the cyst-in-cyst structure of MCN, and the cyst-by-cyst structure of IPMN, to make correct diagnoses. Their location, number, contour, internal structure, internal echo texture, communication with MPD, and presence of solid components are useful US findings to make differential diagnoses. The presence of solid components is related to the malignant potential of cystic lesions. We also emphasize pancreatic cysts that are more than 5 mm in size as a high-risk sign for pancreatic carcinoma and recommend regular follow-up for early detection of pancreatic ductal carcinoma.

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The examiner has to scan the whole breast, detect lesions, diagnose them, and record images during breast ultrasonic examinations. Therefore, the examiner has to acquire the technical skills of examination, the ability to detect lesions, and the ability to diagnose them. In addition, the examiner has to understand the role of each mode (e.g., B mode, color Doppler, elastography), and perform comprehensive diagnosis. Experience with many examinations and knowing the pathological diagnosis are needed to achieve excellent diagnostic performance.

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Ultrasound is a useful tool for examination of thyroid nodules, especially when making the diagnosis of papillary thyroid cancer, which accounts for about 90% of thyroid malignancies. Ultrasound features suggestive of malignancy are irregular shape, hypoechogenicity, ill-defined margin, absence of hypoechoic rim, fine echogenic dots, taller than wide shape, and solid structure. Application of fine-needle aspiration cytology is considered based on these ultrasound features and the maximum diameters of the nodules. Japanese criteria recommend fine-needle aspiration cytology for nodules with many malignant features on ultrasound when the diameter is over 5 mm. When nodules have some single malignant feature, fine-needle aspiration cytology is recommended for nodules over 10 mm. The criteria for recommendation of fine-needle aspiration cytology in the United States or South Korea indicate that fine-needle aspiration cytology is recommended for suspicious nodules 1 cm or over in diameter. Inconsistency exists in the diameter of nodules for which fine-needle aspiration cytology is recommended among Japan, South Korea, and the United States.

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The main purpose of ultrasound for vascular access (VA) is to evaluate the blood vessel before VA creation as well as to evaluate the condition of VA and the development of complications after VA creation. In the former case, it is used to judge the possibility of creating arteriovenous fistula, arteriovenous graft, or subcutaneously fixed superficial artery. In the latter case, VA quality can be judged by observing the blood flow or the peripheral vascular resistance index (RI) and the stenotic lesion. Ultrasound-assisted VA evaluation is a remarkable examination method that enables observation of the function and morphology of VA noninvasively.

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Purpose: Ultrasonic imaging of blood flow in the cardiac lumen is a very useful tool to evaluate the pumping function of the human heart. The speckle tracking technique makes it possible to estimate the blood velocity vector. However, a stable estimation of the velocity vector of blood flow is difficult because signal-to-noise ratios of echoes from tiny blood particles are low. In this study, the speckle tracking technique with averaging of multiple two-dimensional correlation functions was employed for stable estimation of the blood velocity vector. Methods: Multiple two-dimensional correlation functions can be averaged during a very short period by using the echo data acquired by high-frame-rate echocardiography with diverging beam transmission. A steady flow experiment using blood-mimicking fluid (mean fluid velocity 0.2 m/s, flow angle 56° from the transducer surface) was implemented to investigate the effect of the averaging of two-dimensional correlation functions at a frame rate of 6024 Hz. Results: First, to examine the averaging duration required for stable estimation of the flow velocity vector, the accuracies of vector estimates were evaluated at different durations for averaging of two-dimensional correlation functions in the steady flow measurement. It was found that the proposed averaging process with an averaging duration of over 8 frames could reduce the directional error in vector estimation to almost half that of the conventional speckle tracking technique. In subsequent experiments, the averaging duration was set at 12 frames corresponding to 2 ms. Measurements of steady flow at higher velocities were further implemented. The steady flow measurements with higher flow velocities of 0.4 and 0.6 m/s were simulated by changing the frame interval of the echo data at a flow velocity of 0.2 m/s. Although the averaging duration was a mere 2 ms, directional errors at mean flow velocities of 0.2, 0.4, and 0.6 m/s were reduced significantly. In an in vivo experiment of the healthy human heart, to produce a fine B-mode image, the diverging wave transmissions with different steered angles for compounding were interleaved in the transmission sequence. From the in vivo experimental result, the blood velocity vector of the left ventricular cavity showed the flow getting into/out of the cavity in ejection and early diastolic phases. Furthermore, estimated flow directions revealed rotating flow in the cavity in mid-diastole. Conclusion: Our proposed method has the feasibility to visualize the vortex flow by velocity vector mapping without a contrast agent.

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Superb Micro-vascular Imaging (SMI) is a new Doppler imaging technique that employs a unique algorithm to minimize motion artifacts by eliminating clutter signals based on analysis of tissue movement. SMI significantly reduces motion artifacts and allows visualization of low-velocity blood flow in small vessels. In this case report, a case of early cervical pregnancy, which is difficult to detect with power Doppler, is presented to demonstrate the feasibility of SMI for evaluating such cases. At 6 weeks’ gestation from the last menstrual period, ultrasonography showed a thickening of the hyperechoic endometrium with no sign of a gestational sac in the uterus. However, a gestational sac with a white ring was detected in the cervical canal, and the heartbeat of the embryo could not be detected; therefore, the case was suspected of uterine cervical pregnancy or abortion. Conventional power Doppler could not detect blood flow signals around villi and decidua, while SMI showed minute blood vessels in the decidua surrounding the villi. Blood concentration of hCG was 2,899 IU/l. Because a diagnosis of cervical pregnancy was made, MTX 50 mg/m² (70 mg/body) was administrated. Seven days after systemic MTX, reduced blood flow signals around the gestational sac in the cervical canal were demonstrated by SMI. Twelve days after administrating MTX, the pregnant woman experienced hemorrhage and abdominal pain. Discharge of the villi and gestational sac was confirmed. The hCG level was 39 mIU/ml. At the same time, no Doppler signals were detected by SMI in the lower uterine segment endometrium and cervical canal. We believe that SMI has a strong potential for demonstrating the effectiveness of treatment in ectopic pregnancy even during early stages of pregnancy. The clinical usefulness and future potential of SMI in the field of obstetrics and gynecology are remarkable.

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A 72-year-old male with indolent scrotal swelling of one month’s duration was admitted to urology. Scrotal ultrasonography showed abnormalities of the right epididymis and testis. An enlarged epididymal head was heterogeneously hypoechoic, and the border of the right epididymis and testis was ill-demarcated because an epididymal hypoechoic lesion spread into the testis. A sonogram of the right testis revealed multiple small hypoechoic nodules. In addition, there were moderate hydrocele, thick tunica albuginea, and scrotal wall edema. Color Doppler imaging revealed a few signals localized to the periphery of the epididymis. We suspected a right testicular tumor and performed high orchidectomy. Pathologically, there were granulation tissues with abscess, caseation necrosis, and Langhans giant cells. The patient had no history of pulmonary tuberculosis, and Mycobacterium tuberculosis was not detected by Ziehl-Neelsen stain nor isolated from the sputum and urine. We ultimately diagnosed tuberculous granulomatous epididymo-orchitis based on positive interferon-gamma release assays and computed tomography findings of old tuberculous pleurisy. It is often difficult to differentiate this disease from testicular tumor, but the presence of an enlarged epididymis, multiple small hypoechoic nodules in the testis, and Doppler signals localized at the periphery may be useful in making an accurate diagnosis. Findings that suggest inflammatory disease rather than a testicular tumor might be also helpful: scrotal wall thickening, thick tunica albuginea, and hydrocele.

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We report a case of fetal Loeys-Dietz syndrome clinically diagnosed by ultrasonography born to a 33-year-old Japanese primiparous woman without any medical or family history of cardiovascular diseases. At 26 weeks of gestation, fetal echocardiography demonstrated marked dilatations of the aortic annulus and ascending and descending aorta with aortic regurgitation, and a tortuous descending aorta. Severe pulmonary arterial dilatations of the supra-valvular region and main trunk with pulmonary regurgitation were also observed. Fetal cardiac insufficiency including cardiomegaly, pericardial effusion, subcutaneous edema, and ascites developed, and Caesarean section was performed at 31 weeks of gestation. The baby was a 2,262 g (+3.11 SD) male with 1/5-min Apgar scores of 1/3 points, respectively, and his height was 45.0 cm (+1.91 SD). Umbilical arterial blood gas analysis showed pH of 6.860, B.E. of -17.8 mmol/L, and lactate of 7.2 mmol/L, indicating metabolic acidosis. Arachnodactyly, cleft palate/uvula, and arthrogryposis were not observed. He died 21 days after birth due to congestive heart failure. Chromosomal analysis revealed normal karyotype of 46, XY. Genetic diagnosis was not performed because consent was not obtained from the parents. We made a diagnosis of Loeys-Dietz syndrome based on the findings that cardiac insufficiency deteriorated during the fetal and neonatal periods because of severe marked dilation of the bilateral great vessels with regurgitations and a tortuous descending aorta, and characteristic superficial findings of Marfan syndrome were not detected. It is necessary to consider neonatal Marfan syndrome and Loeys-Dietz syndrome when seeing findings such as those in this case. It is expected that the consequence of Loeys-Dietz syndrome detected in the fetal period will be very severe. Prenatal genetic diagnosis will enable us to explain the neonatal consequence.

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