In point-of-care ultrasound, the artifacts that arise from the pleural line and extend to the bottom of the screen without fading are now known as ‘B-lines’, which are evident in patients with pulmonary edema and inflammatory diseases. Many recent prospective studies on the diagnostic performance of lung ultrasound with B-lines have been published, and it has become evident that the presence of B-lines is useful for the diagnosis of cardiogenic pulmonary edema. Lung ultrasound is promising as a modality for the rapid diagnosis of cardiogenic pulmonary edema in prehospital settings and the emergency room, and for monitoring in intensive care units and general wards. As the use of lung ultrasound at the bedside becomes widespread, preset features of the lung will be needed for each ultrasound machine, and research on quantification of B-lines will be necessary. The appropriate selection of lung imaging modalities should also be considered. Furthermore, large clinical trials are needed to investigate whether or not lung ultrasound for the diagnosis of pulmonary edema improves patient care.

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Diagnostic support systems that substitute ultrasound probe scanning technology by a robot have attracted attention. Ultrasound diagnostic support robot systems realize more precise probe positioning as well as application for tele-echography examination for isolated islands and doctorless villages, automatic inspection by robot alone, and training of inexperienced examiners, etc. Therefore, ultrasound diagnostic support robots for various organs have been developed in many institutions in Japan and abroad. In this paper, I summarize the related research on ultrasound diagnostic support robots and describe the robots that my group has been working on. This study was carried out to realize an emergent medical support robot system that reduces the physical and mental burden of not only patients but also doctors and laboratory technicians. In this paper, we describe a serial link-type robotic echography for a diagnostic and therapeutic system that can cope with lateral position diagnosis. Next, we evaluate the mental rotation ability potentially possessed by physicians and laboratory technicians in ultrasound diagnosis. Analyzing unique techniques used by experts and quantitatively indicating the mental rotation ability will expose problems faced by inexperienced examiners and lead to support for reducing the burden on doctors. Next, with the experimenter cooperating with the robot, an experiment was conducted to calculate an intention estimation matrix that measures the direction and size of the probe scan intended by the inspector. As a result, regardless of the positional relationship between the robot and the experimenter, we succeeded in estimating the intention of the probe scan of the experimenter.

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In this paper, two of our investigations of ultrasound image feedback control methods for a probe-holding robot are described. The first is an autonomous positioning system. The proposed algorithm enables the robot to autonomously search and detect the target organ, and obtain a clear ultrasound image. The second is a real-time visual servoing system that tracks the movement of the target organ. The proposed method requires only a normal 2-dimensional B-mode probe for 3-dimensional tracking. The results of testing in human tissue are also described.

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Image-guided procedures are very common and useful for achieving precise and safe minimally invasive surgery with limited visual information. Surgical navigation systems provide surgeons with quantitative and subjective guidance information in minimally invasive treatment. The most critical problem associated with surgical navigation systems is how to deal with soft organ deformation and motion during surgery, and intraoperative imaging is one solution to this problem. Ultrasound imaging is one of the most promising imaging modality as it is commonly and easily usable in a treatment environment, is cost-effective, and has high-speed scanning ability compared with CT and MRI. While many 2D ultrasound image navigation systems have been developed for laparoscopic surgery, we have developed a real-time 3D ultrasound navigation system for fetal endoscopic surgery. We are also developing new procedure called water-filled laparoendoscopic surgery (WaFLES), with which we can obtain 3D real-time and wide ultrasound images during surgery. As for the future of image-guided minimally invasive surgery, intraoperative ultrasound imaging will be a leading technology, and it will be required to make new innovations in both surgical procedures and medical device technologies with medicine-engineering collaboration and seeds-needs matching.

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To realize theranostics using ultrasound and microbubbles, which have a great potential not only for diagnosis but also therapy, we utilize Bjerknes force to enhance the local concentration of microbubbles through the blood vessel network in the human body. We are now developing a method to induce microbubbles independent to flow direction, which is available by introducing a matrix array transducer. Here, we demonstrated that the phase difference between the two focal points to produce an attractive force. Another application we consider is cellular immune therapy by propelling therapeutic cells using acoustic force, where microbubbles attach to the surface of the cells to reduce the density of the aggregations. We confirmed the controllability of the aggregations under ultrasound exposure through an experiment using an artificial blood vessel and fluorescent microscope observation. Finally, we introduce our attempt at robotic control for accurate positioning of a therapeutic transducer. To clarify the system feasibility, we conducted an experiment to evaluate the position accuracy of a parallel link robot for the above-mentioned theranostics.

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The expectation that intersections of various science and engineering technologies such as mathematics, information, control, artificial intelligence, and robot technology with medicine and biology have enormous potential is rapidly growing day by day. Bill Gates said, “If I were a student, I would learn biology,” and Nicolas Negroponte said, “Bio is new digitals.” It is a very clear phrase that predicts that biology will be reconstructed by the fusion of bio and IT technology. Here, the meaning of bio is intended to cover a wide range of bio including biotechnology. In this paper, we review medical digitization (Me-DigIT) in the field of medical ultrasound and core technologies for Me-DigIT.

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High-intensity focused ultrasound (HIFU) is a noninvasive method that can cause complete coagulation necrosis without requiring the insertion of any instruments. The purpose of this study was to evaluate the safety and usefulness of HIFU assisted by ultrasound-computed tomography three-dimensional (US-CT3D) dual imaging for the treatment of hepatocellular carcinoma (HCC). The HIFU system (Chongqing Haifu Tech, Chongqing, China) was used under ultrasound guidance. HIFU ablation was performed in 10 patients with small HCC (≤3 lesions, ≤3 cm in diameter). By transferring the sagittal or axial plane of the 3D US and the CT volume data into a ZioM900 workstation, multiplanar reconstruction images were displayed in a manner resembling conventional US to assist the HIFU treatment. The patients in whom good visualization using B-mode sonography could not be achieved because of the influence of multi-reflections, rib shadows, and unclear tumor margins were successfully treated under the guidance of US-CT 3D dual imaging. The 3D US images obtained as part of the US-CT 3D dual imaging had a high resolution and were useful for examining the area of HCC invasion and for determining the extent of the ablation area. The CT images, which are not influenced by bone shadows or multi-reflections, were useful for detecting the tumors and for visualizing the presence of the intestines in the sonication zone. HIFU treatments were successfully performed in all of the patients with the assistance of US-CT 3D dual imaging.

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Purpose: For myocardial ischemic regions, when medical diagnosis and treatment are applied in the early stage of ischemic heart disease, fatal necrosis of the myocardium can be avoided by prompt reperfusion. Therefore, appropriate and rapid identification of ischemic regions is essential. In the present study, to noninvasively elucidate the propagation characteristics of the myocardial response to electrical excitation in the heart, the propagation of myocardial contraction was visualized by applying ultrasonic measurement of a minute vibration velocity waveform to each point in both the interventricular septum (IVS) and left ventricular posterior wall (LVPW) of the human heart. Methods: By simultaneously applying the phased-tracking method with a high frame rate of over 400 Hz to the IVS and the LVPW, vibration velocity waveforms in the myocardium were obtained at about 3,000 points in both walls. In addition, using a cross-correlation between the resultant vibration velocity waveform at each measurement point and that at the reference point, the delay time of the contraction response at each point from that at the reference point was determined so that the propagation of myocardial contraction could be visualized. Results: In the IVS, the myocardial contraction response propagated at 1.9-3.8 m/s from the basal to the apical side. In the LVPW, on the other hand, the response propagated at 2.0-3.2 m/s from the apical to the basal side. Since the above measurement was simultaneously applied to both walls, it was confirmed that the myocardial contraction propagated from the basal to the apical side in the IVS, and then from the apical to the basal side in the LVPW. These results correspond to the route of the Purkinje fibers. Conclusion: Using the proposed measurement and analysis method, it was shown that propagation of myocardial contraction in the IVS and the LVPW could be visualized by ultrasound.

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Purpose: Dilatation of the thoracic aorta and cardiac dysfunction are long-term complications after abdominal aortic aneurysm repair. Aortic dilatation is related to hypertension, hyperlipidemia, diabetes mellitus, and smoking, which are regarded as risk factors for arteriosclerosis. Cardiac dysfunction without ischemic heart disease is also multifactorial in these patients. It remains unknown whether abdominal aortic aneurysm repair has some impact on thoracic aortic dilatation and cardiac dysfunction. Methods: A retrospective study was conducted on 50 patients who underwent abdominal aortic aneurysm repair. Fifteen age-matched individuals were also enrolled as a control group. We assessed aortic diameter, aortic stiffness, myocardial mass, and cardiac function using computed tomography and echocardiography. Results and Discussions: Ten out of 50 patients (20.0%) had thoracic aortic dilatation during a follow-up period (6.0±4.1 years). The stiffness index of the thoracic aorta increased after surgery for abdominal aortic aneurysm in the thoracic aortic dilation group (p=0.02). In addition, more patients in the aortic dilatation group showed a kinking angle over 60 degrees of the abdomen artificial vessel (p=0.03), lower global longitudinal strain (GLS), and higher cardiac mass. According to univariate logistic analysis, higher abdominal aortic kinking, blood pressure, and hyperlipidemia were important factors for dilatation of the thoracic aorta. Conclusion: Abdominal aortic aneurysmal repair may have adverse effects on thoracic aortic dilatation and cardiac function. Artificial vessel kinking, stiffness index of the thoracic aorta, GLS, and cardiac mass may be useful parameters for assessing thoracic aortic dilatation and cardiac dysfunction. In addition, well-controlled blood pressure and hyperlipidemia are essential in these patients.

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Purpose: Proximal left coronary artery (LCA) lesions are associated with poor prognosis. Transthoracic Doppler echocardiography (TTDE) can be performed in a short time and combined with routine echocardiography. Further, the accelerated coronary flow velocity detected by TTDE reflects the presence of proximal LCA lesions with high specificity. Confirming its reproducibility is crucial for quality control. We aimed to retrospectively investigate machine and sonographer dependence for detecting coronary flow at the site of the proximal LCA. Subjects and Methods: 1)Machine dependency We enrolled 325 consecutive patients who underwent two rounds of TTDE using two different echo machines (Vivid 7 and Vivid E9; GE Vingmed, Horten, Norway) by the same sonographers between 2010 and 2016. 2)Sonographer dependency We enrolled 100 consecutive patients who underwent three TTDE examinations using the same echo machine (Vivid 7) by three sonographers with different levels of TTDE experiences (sonographer 1 and 2: 5 years, sonographer 3: 2 years) between 2010 and 2016. In both studies, the definition of detecting coronary flow at the proximal LCA was the successful digital image acquisition of coronary flow via the pulse Doppler method at that site. If coronary flow was detected, the time for the detection was also analyzed. Patients with revascularization during the period of TTDE examinations were excluded. Results: The detection rate of coronary flow using the Vivid E9 was significantly better than that of the Vivid 7 (68% vs 60%, p=0.01). However, the detection time was not different between the two machines. Also, sonographer dependency for the detection rate (sonographer 1: 77%, sonographer 2: 70%, sonographer 3: 65%, p=0.0486) and the detection time (sonographer 1: 57 sec, sonographer 2: 65 sec, sonographer 3: 86 sec, p<0.01) was observed, which might be associated with TTDE experience. Conclusion: The detection of coronary flow at the proximal LCA may depend on the echo machine and sonographer. Additionally, a learning curve may exist for its detection.

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We report a case of hepatic angiosarcoma. An 80-year-old man with impaired liver function was admitted to our hospital for detailed examination. Contrast-enhanced computed tomography (CECT) revealed a tumor lesion, which was 40 mm in diameter at segment 7 of the liver. Abdominal ultrasonography (US) showed a hyperechoic mass with an inhomogeneous and slightly unclear margin. Contrast-enhanced ultrasonography (CEUS) showed sparse irregular peripheral nodular enhancement on the arterial phase, and partial centripetal filling on the portal phase. The mass was slightly hypoenhanced 10 minutes later on the post vascular phase, but the internal nodular heterogeneous enhancement persisted. The enhancement pattern was similar to that of a typical hepatic hemangioma, but we suspected a hepatic angiosarcoma. Compared to plain CT performed for evaluation of another organ 3 months previously, CECT showed a rapidly growing mass in the same region of the liver with lymph node metastasis of the left gastric artery. We performed ultrasound-guided biopsy, and the lesion was pathologically diagnosed as hepatic angiosarcoma.

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