B-line Elastography Measurement of Lung Parenchymal Elasticity.

This paper proposes a method to determine the elasticity of the lung parenchyma from the B-line Doppler signal observed using continuous shear wave elastography, which uses a small vibrator placed on the tissue surface to propagate continuous shear waves with a vibration frequency of approximately 100 Hz. Since the B-line is generated by multiple reflections in fluid-storing alveoli near the lung surface, the ultrasonic multiple-reflection signal from the B-line is affected by the Doppler shift due to shear waves propagating in the lung parenchyma. When multiple B-lines are observed, the propagation velocity can be estimated by measuring the difference in propagation time between the B-lines. Therefore, continuous shear wave elastography can be used to determine the elasticity of the lung parenchyma by measuring the phase difference of shear wave between the B-lines. In this study, three elastic sponges (soft, medium, and hard) with embedded glass beads were used to simulate fluid-storing alveoli. Shear wave velocity measured using the proposed method was compared with that calculated using Young's modulus obtained from compression measurement. Using the proposed method, the measured shear wave velocities (mean ± S.D.) were 3.78 ± 0.23, 4.24 ± 0.12, and 5.06 ± 0.05 m/s for soft, medium, and hard sponges, respectively, which deviated by a maximum of 5.37% from the values calculated using the measured Young's moduli. The shear wave velocities of the sponge phantom were in a velocity range similar to the mean shear wave velocities of healthy and diseased lungs reported by magnetic resonance elastography (3.25 and 4.54 m/s, respectively). B-line elastography may enable emergency diagnoses of acute lung disease using portable ultrasonic echo devices.

Endothelial dysfunction by flow-mediated dilation assessed ultrasonically in patients with Kawasaki Disease.

Kawasaki Disease (KD) is a febrile disorder seen in infants and young children. One of the most serious complications of the disease is coronary aneurysm. Endothelial dysfunction is considered to underlie the etiopathology of coronary aneurysm. Flow-mediated dilation (FMD), as assessed ultrasonically, is used to observe the endothelial function. The current paper summarizes, by providing a systematic review, the clinical studies that have examined endothelial dysfunction by determining the FMD ultrasonically in patients with KD. A PubMed-based search found eight articles published until 2013. Six studies reported the FMD level to be significantly lower in the patients with KD compared to controls, while two studies reported no significant difference in the FMD level between those with and without KD. Although patients with KD appeared to have endothelial dysfunction in the current summary, most reports have been associated with limitations, such as a small size and no prospective design for vascular outcomes. Further studies are therefore needed to draw definite conclusions regarding whether patients with KD suffer from endothelial dysfunction as determined by the FMD and/or whether this determination can be useful for understanding and managing vascular complications in these patients.

[Overview of Clinical Examination in Nephrology and Urology--Efficacy of Routine Ultrasound in Detection of Chronic Kidney Disease].

PURPOSE: We re-evaluated the usefulness of ultrasound (US) performed in routine examination as a screening procedure for chronic kidney disease. PATIENTS AND METHODS: Of 294 patients screened by US in routine examination, 75 were identified as those with chronic renal damage during a one-month period (March 2013) in our hospital. We examined the patients' clinical background and extracted their characteristics. RESULTS: Thirty-six patients with chronic renal damage were detected out of US in 72 suspected cases, and 39 in 222 unsuspected cases. Among the latter group, US was performed to examine the upper abdomen in 35 cases, and to examine the whole abdomen in 3 cases. Among the latter group, US was performed in a checkup of the liver in 14 cases, as a routine examination for diabetics in 7 cases, and as a screening test for cancer in 4 cases. Among the latter group, US was performed on the request of endocrinologists in 12 cases, surgeons in 6 cases, and cardiovascular teams in 6 cases. CONCLUSION: Many patients with chronic kidney disease were detected by US in unsuspected cases incidentally. In other words, we should note that their physicians often did not intend to look for it at the time of ordering US examination. US may be useful for the detection of chronic kidney disease not only in high-risk cases, but also in low-risk, unsuspected cases.

Evaluation of skeletal muscle elasticity using color Doppler shear wave imaging.

PURPOSE: This study aimed to (1) assess the precision and reproducibility of color Doppler shear wave imaging (CD SWI) by comparing it with shear wave elastography (SWE) via elasticity phantom measurements, and (2) investigate the potential clinical applications of CD SWI in the upper limb muscles by assessing the reproducibility of skeletal muscle elasticity evaluations. METHODS: Four elastography phantoms of different stiffness (6.0-7.5 wt%) were used to assess the precision and reproducibility of CD SWI (compared with SWE) at depths. Typical upper limb muscles of 24 men were also assessed for this comparison. RESULTS: At superficial depths (0-2 cm), the phantom measurements obtained using CD SWI and SWE were similar at all levels of stiffness. Furthermore, both methods were highly reliable, with almost perfect intra- and inter-operator reliabilities. At greater depths (2-4 cm), measurements obtained using both methods were similar at all stiffness levels. Although standard deviations (SDs) of the phantom measurements obtained using both methods at lower stiffness were similar, those at higher stiffness were different. The SD of the CD SWI measurements was < 50% of that of the SWE measurements. However, both methods were highly reliable in the phantom test, with almost perfect intra- and inter-operator reliabilities. The intra- and inter-operator reliabilities of the shear wave velocity measurements for typical muscles of the upper limbs were also substantial in clinical settings. CONCLUSION: CD SWI is a valid method for measuring elasticity, with precision and reliability as high as those of SWE.

Spontaneous regression of lymphovascular invasion and metastasis of malignant melanoma: ultrasound findings.

This report presents a case of malignant melanoma in a 40-year-old male who underwent resection of the tumor in his right ankle. Eleven months after the resection, a subcutaneous mass was observed on his right femur. Ultrasound examination revealed a hypoechoic tubular structure in the right thigh, with a small amount of blood flow in the lesion. Using ultrasound and fine-needle aspiration, the patient was diagnosed with metastasis and lymphovascular invasion of malignant melanoma. Treatment with an immune checkpoint inhibitor was originally scheduled, but the lesion disappeared spontaneously after the fine-needle aspiration.

Sonographic findings of Sister Mary Joseph's nodule from ovarian cancer.

Sister Mary Joseph's nodule (SMJN), which is known as a malignant tumor metastasized to the umbilicus, is a rare condition. We report ultrasonic findings of SMJN secondary to ovarian cancer in a 66-year-old woman. The umbilical tumor was observed as a hypoechoic mass with punctate hyperechoic foci. A pathological specimen obtained by needle biopsy confirmed adenocarcinoma with psammoma bodies. A comparison of the ultrasonographic findings with the pathological findings of the resected specimen suggested that the hyperechoic foci corresponded to psammoma bodies. When hyperechoic foci are observed inside SMJN by ultrasonography, adenocarcinoma from ovarian cancer should be included in the differential diagnosis.

Self-learning followed by telepresence instruction of focused cardiac ultrasound with a handheld device for medical students: a preliminary study.

PURPOSE: This study aimed to assess the feasibility and efficiency of self-learning with or without self-training (subjects performed scans on themselves) and telepresence instruction in focused cardiac ultrasound (FOCUS) education for medical students. METHODS: This study included 24 medical students. The participants initially completed a written pre-test and were randomized into a video lecture (participants watched a video lecture) or self-training (participants watched a video lecture and self-performed FOCUS) group. After finishing self-learning, they completed a written post-test. Then they undertook a skill pre-test and a first perception survey. Telepresence instruction was then provided. Finally, they undertook a skill post-test and a second perception survey. RESULTS: The written post-test total scores were significantly higher than the pre-test total scores (P < 0.001). In the skill pre-test, the scores for the video lecture and self-training groups were not significantly different (P = 0.542). The skill post-test total scores were significantly higher than the skill pre-test total scores (P = 0.008). Forty-two percent of the video lecture group participants agreed that the video lecture was effective preparation for the skill pre-test, while all participants in the same group agreed that the combination of the video lecture and telepresence instruction was effective preparation for the skill post-test. CONCLUSION: This study demonstrated the feasibility and efficiency of self-learning followed by telepresence instruction on FOCUS for medical students.

Ultrasonography in undergraduate medical education: a comprehensive review and the education program implemented at Jichi Medical University.

The concept of point-of-care ultrasound has been widely accepted owing to the development of portable ultrasound systems and growing body of evidence concerning its extensive utility. Thus, it is reasonable to suggest that training to use this modality be included in undergraduate medical education. Training in ultrasonography helps medical students learn basic subjects such as anatomy and physiology, improve their physical examination skills, and acquire diagnostic and procedural skills. Technological advances such as simulators, affordable handheld devices, and tele-ultrasound systems can facilitate undergraduate ultrasound education. Several reports have indicated that some medical schools have integrated ultrasound training into their undergraduate medical curricula. Jichi Medical University in Japan has been providing medical students with ultrasound education to fulfill part of its mission to provide medical care to rural areas. Vertical integration of ultrasound education into a curriculum seems reasonable to ensure skill retention and improvement. However, several issues have hampered the integration of ultrasound into medical education, including a lack of trained faculty, the need to recruit human models, requisition of ultrasound machines for training, and limited curricular space; proposed solutions include peer teaching, students as trained simulated patients, the development of more affordable handheld devices, and a flipped classroom approach with access to an e-learning platform, respectively. A curriculum should be developed through multidisciplinary and bottom-up student-initiated approaches. Formulating national and international consensuses concerning the milestones and curricula can promote the incorporation of ultrasound training into undergraduate medical education at the national level.

Assessment of the risk of disease transmission during fine-needle aspiration cytology under ultrasound guidance by visualization of droplet and aerosol formation.

PURPOSE: Fine-needle aspiration cytology (FNAC) under ultrasound guidance is clinically useful, but there is a risk of spreading infection by generating droplets of contaminated fluids during the procedure. Risk assessment to better control infection remains to be established. The aim of this study was to estimate infection risks during FNAC by visualization of droplet production and deposition using a simulation model. METHODS: The simulation comprised a puncture needle, a device for holding the needle, and a fluid specimen containing fluorescent particles as a model. Simulating each step of FNAC (removal of the inner and outer cylinder and transferring the specimen onto a glass slide), the generation and deposition of droplets were visualized using a laser. RESULTS: After removal of the inner cylinder, an aerosol of droplets in the air surrounding the needle was observed. After removal of the outer cylinder, several large droplets precipitating onto the circumjacent surface were observed. From the beginning of transferring the specimen, a large amount of sizeable droplets first moving away and then precipitating was observed, followed by the production of a cluster of fine droplets drifting and spreading through the air. CONCLUSIONS: Here, the generation of droplets at each step of FNAC, precipitation of large droplets onto the circumjacent surface, and drifting and spreading through the air of fine droplets was visualized. These results emphasize the need for precautions to prevent the transmission of infectious agents during FNAC.

Shear wave speed measurement bias in a viscoelastic phantom across six ultrasound elastography systems: a comparative study with transient elastography and magnetic resonance elastography.

PURPOSE: To quantify the bias of shear wave speed (SWS) measurements in a viscoelastic phantom across six different ultrasound (US) systems and to compare the SWS with those from transient elastography (TE) and magnetic resonance elastography (MRE). METHODS: A viscoelastic phantom of stiffness representing fibrotic liver or healthy thyroid was measured with nine (linear probe) and 10 (convex probe) modes of six different US-based shear wave elastography (SWE) systems using linear and convex probes. SWS measurements of three regions of interest were repeated thrice at two focal depths, coupling the probe to the phantom using a jig. An MRE system using three motion-encoding gradient frequencies of 60, 90, and 120 Hz and TE were also used to measure the stiffness of the phantom. RESULTS: The SWS from different SWE systems had mean coefficients of variation of 9.0-9.2% and 5.4-5.6% with linear and convex probes, respectively, in viscoelastic phantom measurement. The focal depth was a less significant source of SWS variability than the system. The total average SWS obtained with US-SWE systems was 19.9% higher than that obtained with MRE at 60 Hz, which is commonly used in clinical practice, and 31.5% higher than that obtained with TE using the M probe. CONCLUSIONS: Despite the measurement biases associated with the SWE systems, biases were not necessarily consistent, and they changed with the probes used and depth measured. The SWS of the viscoelastic phantom obtained using different modalities increased according to the shear wave frequency used.

[Common carotid arterial diameter and coronary artery disease].

The clinical significance of the diameter of common carotid artery (CCA) measured ultrasonographically has not been sufficiently established. The object of this cross-sectional study was to investigate the relationship of the ultrasonic CCA diameter with coronary artery disease (CAD). In the male patients (n=169, mean age: 61 years) who had no apparent carotid arterial stenosis and cerebrovascular disease, a history of CAD, current smoking, body mass index, blood pressure, hemoglobin A1c, serum low-density-lipoprotein cholesterol, estimated glomerular filtration rate and ultrasonic measures of CCA diameter were analyzed. A total of 25 patients had a history of CAD (15%). The CCA diameters of patients with CAD were significantly higher than those of patients without CAD (7.9 +/- 1.0 mm and 7.4 +/- 0.9 mm; p = 0.01). Receiver operating characteristic curve of boundary value of CCA diameter revealed an area under the curve to identify the patients with CAD (0.63, p = 0.04). When the cut off value was considered 8.5 mm, the odds ratio was 4.50 (95% confidence interval = 1.71-11.84, p < 0.01), and the ratio were not largely altered in multivariate logistic regression analyses. The CCA diameter may therefore serve as a useful predictive marker for CAD in men.

Educational courses for physiological function examination at Jichi Medical University: practical trainings in ultrasonography.

To foster work-ready general physicians, Jichi Medical University has developed various clinical teaching practices since its foundation. The educational courses for clinical laboratory medicine, being one of them, adopt practical trainings in ultrasonography, which is essential in practical medicine today. The aims and the specifics of the trainings adopted in the seminar of ultrasound and the required or the optional subjects of Bedside Learning (BSL) at Jichi Medical University are reported.

Degradation of ultrasound probes caused by disinfection with alcohol.

The aim of this study was to clarify the degree of degradation of ultrasonic probes that results from their disinfection with alcohol. No defect in the ultrasound beams was found in any of the probes, but a significant decrease of the brightness was found after a certain period of use of the linear-type probe. Disinfection with alcohol may degrade ultrasound probes despite its high degree of effectiveness in preventing iatrogenic bacterial transmission.

Comparison of methods for evaluating bacterial contamination of ultrasound probes.

PURPOSE: To determine suitable methods for evaluating bacterial contamination of ultrasound probes. METHODS: We compared probe imprinting, swab streaking, and swab suspension methods for evaluating bacterial contamination of ultrasound probes. RESULTS: Experimental and clinical investigations showed that the sensitivity for detecting bacterial contamination of ultrasound probes was higher with probe imprinting than with swab methods. Probe imprinting was very simple and required only agar plates. CONCLUSION: Probe imprinting was the most suitable method for evaluating bacterial contamination of ultrasound probes.

Analysis of refractive artifacts by reconstructed three-dimensional ultrasound imaging.

PURPOSE: Refractive artifacts are frequently encountered in clinical settings, and they have been analyzed on the basis of conventional two-dimensional (2-D) ultrasound (US) images, but this method is restricted to monoplane data and is limited by its inability to assess the three-dimensional (3-D) structure of refractive artifacts. The aim of this study was to evaluate the role of reconstructed 3-D US images in the analysis of refractive artifacts. METHODS: The following representative refractive artifacts were analyzed on the basis of reconstructed 3-D US images: (a) a distorted image of a fine tube behind a cyst (balloon); (b) a deformed image of the bottom of a balloon; and (c) a duplication artifact due to the acoustic lens effect. RESULTS: (a) A tube was imaged as a fine echogenic line with two points of sudden interruption, unlike a curved needle, which was imaged without interruption. (b) 3-D US allowed us to visualize the mode of deformity in the image of the bottom of a fluid-filled balloon in a water bath. When the acoustic velocity in the fluid was greater than that in the surrounding water, the bottom of the balloon appeared to be shrunken. When the acoustic velocity in the fluid was less than that in the surrounding water, the bottom of the balloon appeared to be swollen. (c) When we placed two pieces of white chicken meat in front of a fine needle, the needle was duplicated in the resulting image. In this case, the needle appeared to be vague and fuzzy. In this case, 3-D US did not add further information to the 2-D images. CONCLUSIONS: Our study suggests that reconstructed 3-D US images provide a better understanding of the mode of refractive artifacts than do 2-D US images.

Analysis of posterior echoes using reconstructed vertical ultrasound images.

PURPOSE: To evaluate the role of vertical images reconstructed using 3-D data in the analysis of posterior echoes. METHODS: Reconstructed vertical images of US phantoms with the following artifacts were retrieved and analyzed: acoustic shadowing (clean and dirty); posterior echo enhancement (with/without lateral shadowing); and reverberation artifacts (clean and dirty). RESULTS: For acoustic shadowing, a stone and posterior clean acoustic shadowing were imaged as an echogenic mass or an echogenic ring containing a central echo-free area. However, the stone and dirty acoustic shadowing were imaged as an echogenic mass or an echogenic mass consisting of many fine echo spots disseminated throughout the whole mass. For posterior echo enhancement, when lateral shadowing is present, the cyst and posterior echo enhancement are imaged as a round anechoic mass or a triple circle consisting of a thin anechoic outer rim, an echogenic ring, and an anechoic center. However, when lateral shadowing is absent, they are imaged as a round anechoic mass or a double circle consisting of an echogenic outer rim and an anechoic center. For clean reverberation artifacts and dirty reverberation artifacts, vertical images of clean reverberation artifacts consist of either a homogeneous echogenic area or an absent signal. However, vertical images of dirty reverberation artifacts consist of a homogeneous echogenic area and an area consisting of fine echo spots. CONCLUSION: Our study suggests that reconstructed, previously unattainable, vertical plane images help us better understand the mode of posterior echoes.