Development of the diagnostic ultrasound system ARIETTA 850

Transcription

1 Technical Report Development of the diagnostic ultrasound system ARIETTA 850 Tetsuo Watanabe 1) Akifumi Sako 2) Takehiro Tsujita 1) Nobuhiko Fujii 1) Teruyuki Sonoyama 2) Toshinori Maeda 2) Kazuhisa Kozai 3) 1) Products R&D Division 1, Diagnostic R&D Division, Hitachi, Ltd. Healthcare Business Unit 2) Engineering R&D Division 1, Diagnostic R&D Division, Hitachi, Ltd. Healthcare Business Unit 3) Diagnostic Systems Division - First Division, Hitachi, Ltd. Healthcare Business Unit Hitachi, Ltd. Healthcare Business Unit (HHBU) was formed as the healthcare section of Hitachi group in April ARIETTA* is a premium class diagnostic ultrasound system for general applications. It has been developed as Hitachi s flagship model concentrating Hitachi s resources to target the No.1 position in global market share of diagnostic ultrasound systems. Key Words: Key Words: 4G CMUT, efocusing, RVS, RTE, SWM 1. Introduction 1.1 Background to the development With the expansion in the number of disciplines using ultrasound technology in clinical practice, diagnostic ultrasound systems are experiencing increased market growth, with a growth forecast of 3% to 5% between 2015 and Hitachi s growth strategies include Aiming for No.1 position in Global Market Share and a Leading Company Providing Clinical Innovation. Pure Image: Premium image quality with a wide range of parameter adjustment to meet the individual needs of examiners and patients. Seamless Workflow: Workflow streamlined to reduce the burden on examiners and patients. Your Application: Unique and distinctive applications, not available from other companies, that fulfill clinical goals. 1.2 Purpose of the development Led by clinical demands in the diagnostic ultrasound market, Hitachi is developing unique applications in the three main clinical areas: radiology, gynecology, and cardiovascular. The ARIETTA* 1 850, a premium class diagnostic ultrasound system for general applications, has been launched as Hitachi s flagship model to increase its global share in the market. 1.3 Product concepts The ARIETTA 850 (Figure 1) has been developed around the three main concepts: Pure Image, Seamless Workflow, and Your Application, providing a premium class diagnostic ultrasound system that meets users expectations in all aspects of image quality, operability, and providing advanced applications. Figure 1: ARIETTA MEDIX VOL.67 XX-E242

2 2. Pure Image Returning to diagnostic ultrasound basics, we have sought improved performance in the three major aspects of imaging spatial, contrast, and temporal resolution advancing fundamental performance using Pure Symphonic Architecture technology (Figure 2). Probes / Frontend Variable Beamformer Active Backend OLED Monitor OLED Monitor: Organic Light Emitting Diode Monitor Figure 2: Pure Symphonic Architecture 2.1 Electronic convex probe C252 A single-crystal piezoelectric material with an electromechanical coupling coefficient of more than 90% has been implemented in the electronic convex probe C252. Compared to conventional probes, it has acoustic characteristics that include a broader bandwidth and higher sensitivity (Figure 3). By exploiting the wide bandwidth of this probe, ARIET- TA 850 s cutting-edge imaging technology is able to extract even more uniform image quality from superficial to deep areas in abdominal examinations. These technologies support the increase in throughput of abdominal examinations necessary in the modern healthcare environment, improving the comfort of both examiner and patient, whilst enhancing exam efficiency G CMUT (CMUT Linear SML44 probe) Hitachi was the first company to put the CMUT (Capacitive Micro-machined Ultrasound Transducer) using next-generation silicon wafer technology into practical use. 4G CMUT is the latest ultra-wide bandwidth probe adopting Hitachi s unique CMUT technology (Figure 5). Unlike conventional transducers such as those using piezoelectric ceramics, the acoustic impedance of CMUT is closer to that of the human body, so CMUT can transmit an ideal ultra-short pulse waveform with an ultra-wide frequency bandwidth not achievable with conventional probes. Hitachi s latest CMUT technology unique to 4G CMUT, optimizes the CMUT cell structure and uses sophisticated imaging algorithms to achieve an unprecedented level of both spatial resolution and sensitivity at depth. The 4G CMUT is able to selectively drive the grid (matrix) arrangement of CMUT cells with a high degree of freedom, controlling the ultrasonic beam shape in the elevational plane (fixed in conventional probes), to optimize the beam width throughout the field of view. CMUT chip CMUT cell Transducer sensitivity Conventional transducer Frequency High voltage Vibrating membrane (insulating material) Figure 3: C252 and its frequency spectrum Furthermore, to enhance usability, its shape has been pared near the probe face whilst maintaining the open width in the elevational plane. This improves tilt operability in intercostal spaces whilst maintaining full contact with the probe face (Figure 4). Vacuum cavity (Height ~ nm*) Cross section of CMUT cell *nm=1/10 9 m Figure 5: Structure of the 4G CMUT CMUT chip is packed with many CMUT cells in a matrix array In contrast to the conventional use of multiple probes to cover the different clinical applications, 4G CMUT offers a one probe solution, a linear probe that can be employed across a wide range of ultrasound applications achieved using its ultra-wide bandwidth and automatic control of the elevational beam width 1) (Figure 6). 4G CMUT (2-22MHz) Transducer sensitivity Low Mid High Figure 4: C252 intercostal scanning Frequency Figure 6: 4G CMUT frequency spectrum 2 MEDIX VOL.67 XX-E242

3 2.3 HI Framerate and efocusing realized by the Variable Beamformer HI Framerate ARIETTA 850 is equipped with HI Framerate, a multidirectional simultaneous reception technology that can generate multiple reception beams from one transmission. This optimizes the balance between high spatial resolution and high temporal resolution in B-mode and Color Doppler imaging (Figure 7). Deterioration of lateral resolution Transducer elements Transmission focus point Transmission beam shape Figure 8: Conventional beam transmission Transmission Synthesis Figure 7: HI Framerate Off (left) and On (right) efocusing In beam forming during reception for diagnostic ultrasound systems, the signals received by the transducer from each sample point along the reception beam are given a delay time before being phased and summed, so that the resulting reception signals are focused for all sample points. This is dynamic focus technology on reception. In transmission beam forming on the other hand, a single transmission focus point is set, and the transmission beam is formed by giving a delay time to each transducer element at the time of transmission. Consequently, as shown in Figure 8, the transmission beam width is narrow and the lateral resolution is good at a depth near the transmission focus point, but at other depths away from the focus point, lateral resolution deteriorates. efocusing reduces transmission focus dependency using HI Framerate, a multidirectional simultaneous reception technology. As shown in Figure 9 (a), the position of the transmission beam is shifted in such a way that the reception beam fields resulting from each single transmission overlap, with the result that a synthetic reception beam can be created. This effect is described taking scattering point as an example of image formation. In conventional transmission beam forming, if B-mode images are created from simultaneous multidirectional reception signals obtained from a single transmission, the lateral resolution of the image of point is low from each transmission wavefront as shown in Figure 9 (b), in the same manner as the lateral resolution deteriorates at a depth away from the transmission focus point. However, by synthesizing the reception signals using the phase information from each transmission, the phases will match at the position of point. In other positions, the signal components attributable to this scatterer are canceled out through the process of synthesis and result in B-mode images with improved lateral resolution as shown in Figure (a) Reception field and scattering point in each transmission Reception beam field (Formed by multidirectional simultaneous reception) (b) B-mode images of scattering point formed by a single transmission Figure 9: Effects obtained by efocusing (c) B-mode image by efocusing 9 (c). This process of synthesis can be interpreted as transmission beam focusing for sample points at every depth, i.e., realizing dynamic transmission focusing. Since reception also uses dynamic focusing as in the conventional models, efocusing achieves dynamic focusing in both transmission and reception. Furthermore, the reception signals synthesized from multiple transmissions contribute to an improved signal-to-noise ratio and thus improved penetration. Examples of B-mode images obtained by efocusing are shown in Figure 10. Thanks to the effect of dynamic focusing in transmission and reception, efocusing reduces the transmission focus dependency experienced in conventional models, and eliminates the need to set a transmission focus depth. Therefore, in addition to providing high-quality B-mode images with excellent penetration, it also contributes to improved workflow by reducing examination time. 3 MEDIX VOL.67 XX-E242

4 Figure 10: efocusing Off (left) and On (right) 2.4 High quality imaging achieved by the Active Backend with a wide range of image quality parameter adjustments to meet the individual needs of examiners and patients. Ultrasound diagnostic imaging can be examiner-dependent in terms of differences in adjustment and preference. It can also be patient-dependent in terms of differences in body physique and constitution, as well as region-dependent, with examinations that cover superficial tissues, abdomen, obstetrics, cardiovascular, etc. This brings about the need for a wide range of image parameter adjustments. ARIETTA 850 is programmed with multiple dedicated ultrasound image adjustment parameters that have been refined over the development of our previous platform portfolios, including the HI VISION, ProSound* 2, and ARIETTA series, and are thus capable of offering a wide range of image quality adjustments to provide images suited to each type of examination, ranging from quantitative to morphological (Figure 11). 〇 Qualitative evaluation: Images with a wide dynamic range, capable of visualizing the detailed information of soft tissues. 〇 Morphological evaluation: Higher contrast, structure-emphasized images for better understanding of morphology. Figure 11: Image parameter adjustments for qualitative evaluation (left) and image parameter adjustments for morphological evaluation (right) Further B-mode image adjustment parameters have been introduced, dedicated to meeting clinical needs with the AR- IETTA 850: Spatial compounding Spatial compounding improves contrast resolution and provides tissue border emphasis. ARIETTA 850 uses compounding techniques that exploit the multidirectional information more effectively to achieve natural edge enhancement. This allows improved spatial resolution, reduced blurring, and edge enhancement whilst maintaining conventional spatial compounding benefits. HI REZ* 3 +BCF The BCF (Border Clear Filter) improves visibility of the endocardial lining and valves in cardiovascular applications. Combined with HI REZ it provides superior definition resulting in improved examination efficiency in cardiovascular and obstetric exams. Low Echo Reduction Adjusts low echo signals to provide image clarity with minimum noise. Grayscale Enhancement Adjustment of both high and low grayscale echo signals to optimize contrast with a single parameter, thereby contributing to improved workflow. 2.5 Improvement of contrast resolution by organic EL monitor B-mode, the abbreviation of Brightness mode, is the fundamental diagnostic ultrasound mode. The B-mode needs to depict the internal structure of a biological tissue in shades of gray, or gradations of white and black. Among the important indicators for this grayscale performance is contrast resolution. If the monitor that displays ultrasound images has a poor gray scale i.e., if the contrast ratio is low the system cannot achieve high contrast resolution. Organic Electro-luminescence (EL) monitors are made up of EL elements which emit light in a process known as electrophosphorescence. The display of black is clearly depicted by blocking the emission of light from each element, thereby achieving a high contrast ratio. Even in a high performance liquid crystal monitor, the contrast ratio is roughly 1000: 1, compared to that of an organic EL monitor which achieves 250,000:1. It can be said to be the most suitable display monitor for diagnostic ultrasound systems. 3. Seamless Workflow 3.1 Operating console Ultrasound examinations are performed in real-time, most often with the examiner facing the patient, so simplifying operations and reducing the examination time brings benefits both to the examiner and patient. In abdominal ultrasound, commonly used adjustments of Cine Search after Freeze, and Bodymark adjustment to indicate the region imaged, are repeated for each recorded image. With a conventional operating console where the same track ball is used both for Cine Search and Body Mark adjustments, there is a constant need to switch Track Ball priority. ARIETTA 850 comes equipped with independent devices for carrying out Cine Search after Freeze and Bodymark adjustment. The Freeze switch periphery Rotary Encoder is used for Cine Search after Freeze, and Track Ball and Rotary Encoder accompanying the Track Ball for Bodymark adjustment. This eliminates multiple key strokes during each examination (Figure 12). 4 MEDIX VOL.67 XX-E242

5 Furthermore, the Measurement Caliper, Track Ball, Rotary Encoder accompanying the Track Ball, Store, and Freeze are arranged for operation with the hand fixed in position on the palm rest. By ensuring an adequate depth of the palm rest, unnecessary twisting of the wrist when accessing these controls is eliminated. In ARIETTA 850, L and R switches have been added to Enter and Undo, enabling shortcuts for various complex functions, contributing to ease of use and reduced examination times. (Figure 13). Rotary Encoder accompanying the Track Ball Store Measure. Caliper Freeze & Gain Track Ball Figure 12: Operating console layout 3.2 System design to prevent Visual Display Terminals (VDT) syndrome Cable management realized by Ergonomic design Prevention of VDT syndrome The ultrasound examiner can suffer physical stress when examinations are performed with the body twisted into an unnatural posture 2). ARIETTA 850 has been designed with a focus on reducing the burden on the examiner s neck and shoulders to prevent VDT syndrome. The console panel and monitor arms have a large range of motion to allow the examiner to maintain an optimal working posture either in the seated or standing position (Figures 14 and 15). Operating console: Moves up and down by mm and swivels by 25 degrees Monitor: Moves up and down by 172 mm, swivels 360 degrees, and slides back and forth by 224 mm As a result, the line of sight in the seated position falls about 10 degrees below the horizontal, as recommended by the Japan Society of Ultrasonics in Medicine 3). Furthermore, another joint has been added to the monitor arm so that the monitor can move smoothly back and forth in parallel and each examiner can easily find an optimal adjustment. (Figure 16) Although such measures would be likely to increase the size of the system, a compact body size has been achieved. Cable management Challenges in the design of the body of the diagnostic ultrasound system include measures against VDT syndrome and improved management of transducer cables. In conventional models, transducer cables can get entangled whenever the examiner switches transducers during or between examinations. ARIETTA 850 has multiple side hooks on both sides of the operating console, one dedicated to each probe holder. The side hook is designed for the cable to be rolled up in such a way that when the probe is placed in the holder, the direction of the cable is horizontal to the direction in which the transducer is removed from the holder. As a result, when the transducer is removed, its cable does not easily get entangled with others. (Figure 17). Consideration has also been given to the form, material and processing so that the cable can be pulled out smoothly, but is also held securely on the hook. To be easily located, the hooks are designed to protrude from the sides of the console, at an angle against the root of the cable so that it is easily pulled out through the hook. They are also designed to retract under the console with a Figure 13: Operating console, L and R switches Figure 17: Cables do not become entangled when the transducer is removed ±25 172mm 224mm mm 700mm 360 Figure 14: Horizontal movement range Figure 15: Vertical movement range Figure 16: Back and forth movement of the monitor 5 MEDIX VOL.67 XX-E242

6 single touch so they can be folded away when the system is used in a small examination room or being moved to another place. Even in the retracted position, the hooks are designed to allow cables to be pulled out smoothly or held firmly. 3.3 Automatic setting of functions Simplification is sought of the many complex ultrasound functions, especially encountered in the field of cardiology. Automation of various functions has been developed for the premium class, cardiovascular diagnostic ultrasound system, LISENDO* These have been migrated to ARIETTA 850, with some examples described below. In Simpson s measurement, the end-diastolic (Ed) and end-systolic (Es) phases are automatically detected, and the B-mode images representing Ed and Es automatically displayed on the screen side by side. This is followed by automatic tracing of the Ed/Es endocardial linings, allowing calculation of Left Ventricular Ejection Fraction (LVEF) as the left ventricular systolic function index, with less than half the number of keystrokes (Figure 18). In Doppler measurements, automatic setting of the sample gate position is now possible by image recognition software. Machine learning techniques are employed to determine the type of section displayed with automatic setting of the sample gate position as the examiner would do manually, improving accuracy and versatility. This function also applies to the Dual Gate Doppler (Figure 19) mode, and is expected to make this application more popular. 3.4 Protocol Assistant During the ultrasound examination, the quantity and quality of ultrasound images recorded can be heavily operator-dependent. These differences between operators place an additional load on the radiologist or other clinicians during interpretation and reporting. Protocol Assistant supports standardization by using preregistered protocols that define the type of images recorded, the imaging sequence, and image parameter settings. The list of images to be recorded is displayed on the screen (Figure 20), so that the examiner can follow the set protocol. Preregistered image quality adjustment settings are automatically reproduced for each image selected, and the list is sequentially checked off as each one is recorded, so no images will be missed. The use of the Protocol Assistant results in standardized alignment and adjustment of images, reducing examiner-dependency and easing the workload for the image interpretation and reporting. Moreover, examination efficiency resulting in shorter exam times can be expected. Figure 20: Example of examination screen when using Protocol Assistant Figure 18: Semi-automation of Simpson s measurement Figure 19: Automatic setting of sample gates for Dual Gate Doppler With ARIETTA 850, preregistration of protocols is simplified and routines performed on the system can be memorized as protocols. However, maximum flexibility is incorporated with the provision of an Auto Pause function which automatically pauses the protocol when changes in the mode (B, color Doppler, etc.), are detected and the system judges it to be an examination outside the specified protocol range. This avoids the need to pause the protocol manually or images being unintentionally linked to the protocol. Protocol Assistant contributes significantly to improving examination efficiency and quality and the ease of preregistration will increase its acceptance. 4. Your Application 4.1 Breast elastography Currently there are over 90,000 people with breast cancer in Japan. Predicted to be the most common cancer in women 4), the number is growing every year. With the knowledge that cancerous tissue becomes stiffer, and that this stiffening is believed to start from the early stages of the development of the cancer, Hitachi developed and released the technology, Real-time Tissue Elastography* 5 (RTE) in 2003, as a 6 MEDIX VOL.67 XX-E242

7 non-invasive ultrasound method for imaging tissue elasticity (stiffness). Today, it is in routine clinical use. Ongoing developments have improved the simplicity, objectivity, and quantification in order to promote its widespread use 5), and the technology continues to evolve. To follow the product concept of Seamless Workflow with the ARIETTA 850, only the controls positioned around the Track Ball need to be activated to simultaneously access Auto Frame Selection (AFS) for automatically selecting the appropriate frame, and Assist Strain Ratio (ASR) for automatically selecting the appropriate region within the frame for measurement (Figure 21). Combining this with the No Manual Compression approach recommended in the WFUMB (World Federation for Ultrasound in Medicine and Biology) guidelines, images with high reproducibility can be quantified with a minimum number of operations, improving accuracy by reducing examiner-skill dependency. 4.2 Liver elastography (RTE, SWM) Recently, new drugs have become available that are effective for the eradication of the hepatitis C virus. However, it is recognized that it is important to follow-up the progress of liver fibrosis after virus elimination. In addition, there is an increase in patients with lifestyle diseases which may also lead to the increase in non-alcoholic steatohepatitis (NASH), a form of non-viral hepatitis. Liver biopsies are effective for the diagnosis of these chronic liver diseases, but because of their invasive nature and cost, they cannot be carried out repeatedly on a large population. In contrast, non-invasive evaluation of liver fibrosis using ultrasound elastography can be made regularly and its use has increased rapidly in recent years. ARIETTA 850 offers both RTE, a strain imaging method, and Shear Wave Measurement (SWM), a point ROI movement Figure 21: Seamless execution of ASR Automatic setting shear wave speed measurement method for liver elastography (Figure 22). RTE can be used to estimate the stage of liver fibrosis from the LF index, calculated from an analysis of the change in the RTE strain image pattern as fibrosis progresses 6). It has been reported that the LF Index correctly reflects the degree of liver fibrosis without influence from inflammatory processes 7), increasing its clinical value. SWM measures the propagation speed of shear waves in tissue, (Vs), which has been shown to increase with increasing liver stiffness. However, the propagation of the shear wave can be disrupted by an unsteady examiner s hand, movements by the patient or vascular flow. Thus it is difficult to judge the validity of the measurement results with the Vs value alone. Hitachi has added a reliability indicator, the VsN (display of the effective rate of Vs as a percentage), to each shear wave velocity measurement, giving a quantitative indication of the appropriateness of the measurement 8). Clinical studies have shown that adopting only measurements in which VsN is over 50% improves Vs measurement accuracy 9). With these liver elastography techniques, the ARIETTA 850 is capable of quantitative liver fibrosis evaluation, aiding the diagnosis and management of chronic liver diseases. Future developments will provide applications for comprehensively evaluating liver disease, adding functions for separately evaluating fibrosis and inflammation by the simultaneous measurement of RTE and SWM, and by attenuation measurement functions for assessment of fatty livers. 4.3 Real-time Virtual Sonography (RVS) Deaths from liver cancer in Japan were highest in the first half of 2000, and the number has been gradually declining since then. Still, the annual number of deaths exceeds 30,000 people, making it a disease requiring serious control measures 10). Radio Frequency Ablation (RFA) is one type of local treatment for liver cancer. With this minimally invasive surgery, an electrode needle placed within the tumor can thermally coagulate it with radio frequency waves. For effective RFA treatment, accurate electrode placement within the tumor is crucial. In 2003, Hitachi developed the RFA needle guidance navigation system Real-time Virtual Sonography* 6 ( RVS) 11). The RVS technique fuses CT and MR images with the real-time ultrasound, and by tracking the movement of the ultrasound probe, can reconstruct and display the corresponding cross-sectional CT or MR image Figure 22: Liver elastography modes Left: RTE, Right: SWM 7 MEDIX VOL.67 XX-E242

8 alongside the real-time ultrasound. Thus lesions better identified by CT or MR imaging, can be accurately targeted during RFA treatment under ultrasound guidance. Recent advances in RFA adopted for the treatment of large tumors have included double cauterization by multiple punctures/cauterizations using a mono polar electrode needle, or puncture/simultaneous cauterization using multiple bipolar electrode needles. The thermal coagulation area is determined by the position of the electrode, so in order to improve the accuracy and ensure an adequate treatment margin, pre-treatment planning of the electrode needle position within the tumor and simulating the resultant shape of the thermal coagulation area is desirable. The new fusion technology 3D Sim-Navigator combines navigation and simulation using RVS 12)13). During RFA treatment, simulation of the electrode needle positions within the lesion are displayed three-dimensionally (Figure 23). In addition, by reconstruction of the C plane, the plane passing through the center of the tumor orthogonally to the line of the needle path, it is possible to determine the positional relation between them in real-time. Furthermore, by simulating the electric field (E-field), determined from the position of the electrode on the CT or MR image, the distribution of the heat dissipation can be easily checked (Figure 24). This simulation can be repeated varying the electrode insertion points and needle positions until the optimal simulation lines are obtained, offering a new degree of freedom to treatment planning. Figure 23: 3D Sim-Navigator display Figure 24: 3D Sim-Navigator E-field display In addition, by tracing the needle tip using CIVCO s VirtuTRAX Bracket, the actual needle position can now be monitored during RFA. And further, by combining the use of CIVCO s omnitrax Bracket, it is possible to maintain the synchronization of CT or MR images with the real-time ultrasound even if there is some patient movement during the procedure. In this way, RVS is evolving to keep pace with the advances in RFA methods, contributing to the accuracy of liver cancer treatment by providing pre-treatment planning, real-time needle navigation, and monitoring of the ablation area. 4.4 Obstetrics 3D/4D Display In the field of obstetrics, to enhance pre-natal fetal assessment, Hitachi has harnessed the new technologies in the ARIETTA 850 to transform the 3D/4D applications that include volume scanning, volume calculation, rendering, and 3D application software programs. Both the multidirectional simultaneous reception technology HI Framerate and transmission/reception dynamic focusing technology efocusing are applied during data acquisition for the 3D display, and HI Framerate for the 4D display application to improve basic performance. HIDEF3D mode used to acquire high precision volume data is also capable of using efocusing. This reduces focus-dependency, enhancing the clarity of 3D images and improving signal-to-noise ratio. The engine used for constructing volume data and for processing signals has been integrated with the new Active Backend. Sampling rate conversion processing not required in intermediate processing has been eliminated, achieving volume calculations with a minimum decrease in spatial resolution. As a result, both spatial and temporal resolution are optimized and a volume rate twice that of conventional levels is realized. ARIETTA 850 has adopted the high performance GPU (Graphics Processing Unit) for 3D rendering to enhance the volume data display rotation/magnification and reduce operation time responses. In particular, 4Dshading* 7 mode14) can now be attained with double the calculation speed. Response times in the 3D application software have also improved. A reduction in 40% has been realized between the time taken from the start of 4D mode data gathering to display, and an 80% reduction in the time for completing HIDEF3D mode display. These examples illustrate the way in which ARIETTA 850 is meeting operability, temporal and spatial resolution requirements for 3D/4D display in obstetrics, significantly contributing to enhanced examination efficiency. 3D/4D ultrasound images can provide additional, detailed surface rendered information for gaining a better understanding of fetal morphology, as well as playing a role in parental reassurance. Clear definition of morphological characteristics and a rendering that conveys a more natural appearance are desired, for which Hitachi has developed a new 4Dshading, 4DshadingFlow, and 4Dtranslucence functions. New 4Dshading function The 4Dshading rendering was developed to give a more realistic 3D reconstruction by simulating the scattering of light from the surface. ARIETTA 850 comes with an advanced 4Dshading function adding shadowing to giving a 8 MEDIX VOL.67 XX-E242

9 more realistic appearance of natural shadows and skin texture, clarifying shape, and providing a 3D display giving a more natural impression. (Figure 25). Figure 25: Conventional 4Dshading (left) and new 4Dshading (right) (using CIRS fetal phantom) 4DshadingFlow function Hitachi has adapted the 4Dshading technology for Doppler, offering the new 4DshadingFlow function on the ARI- ETTA 850, using algorithms to mimic the scattering of light and to give a more realistic appearance to the blood flow (Figure 26). The 4DshadingFlow function enhances the display of blood flow in minute vessels. Figure 26: 3D eflow image using conventional 3D (left) and 4DshadingFlow (right) 4.5 Estimated Fetal Weight (EFW) measurement assist function EFW is an indicator that can be used to evaluate fetal development. A routine ultrasound check normally involves measurement of specific cross-sections of the fetal head, abdomen, and femur and the measurement results compared with the reference values to establish normal fetal development or otherwise. In EFW measurement, multiple measurement points are set using Track Ball operations, and errors incurred from each individual measurement will be compounded in the calculated EFW. Simplifying the marking of the appropriate measurement points could improve accuracy. Hitachi has developed a measurement assist function which sets measurement points automatically once the characteristics of the measurement object has been determined. For the head and abdomen, a search is first performed for elliptical regions that could represent the head and abdomen. A detailed elliptical shape with reference to the edge information is positioned and measurement points are set following the recommended protocols for fetal measurements (Figure 28). For the detection of the measurement points in the lower limb, first a baton-shaped area resembling the femur is recognized and from this, a detailed search carried out to detect the ends of the femur by tracking the brightness of the echoes. The measurement points are set taking into account the curvature of the detected area. Using these assist functions, simple operations are used to automatically determine the correct measurement points. Once the examiner confirms that the measurement points are within acceptable limits, the measurement can be finalized. This measurement assist function with excellent operability and measurement accuracy contribute to improving examination efficiency for routine obstetric ultrasound checks. 4Dtranslucence function The new 4Dtranslucense function displays the inner morphological information by visualizing only the organ boundaries within the volume data (Figure 27). Offering a significantly different approach to the conventional surface rendering, this function renders only boundaries providing a 3D display of the shapes of inner organs. Figure 27: Normal 3D display (left) and 3D display using 4Dtranslucence rendering mode (right) Figure (A) Heart model, (B) Blood vessel model using Kyoto Kagaku s fetal phantom Figure 28: Setting of measurement points on the fetal head (BPD) 4.6 Cardiac phase analysis by Dual Gate Doppler Dual Gate Doppler is a technology that simultaneously displays Doppler waveforms from two different points in real time. A combination of Tissue Doppler Imaging and Pulsed Wave Doppler (TDI/PW) allow simultaneous evaluation of wall motion and hemodynamics and enables measurement of E/e (the ratio of the early diastolic transmitral velocity to early diastolic mitral annular velocity) and is widely used in the clinical setting (Figure 29). Recently, in addition to E/e, the time interval between the onset of early transmitral flow velocity (E) and that of early diastolic mitral annular velocity (e ), T(E - e ), has been shown to be a good predictor of elevated left ventricular filling pressure in patients with sinus rhythm. In patients with atrial fibrillation, the simultaneous 9 MEDIX VOL.67 XX-E242

10 recording of E and e using Dual Gate Doppler echocardiography and the analysis of T(E e ), in addition to E/e, improved the accuracy of evaluation of LV filling pressure 15). Figure 29 Cardiac phase analysis by Dual Gate Doppler 5. Conclusion ARIETTA 850 provides customer values befitting a premium class products in all aspects of image quality, workflow, application. Hitachi is committed to continuing to contribute to the progress of medicine as the leading company of diagnostic ultrasound systems. *1 ARIETTA, *2 ProSound, *3 HI REZ, *4 LISENDO, *5 Real-time Tissue Elastography, *6 Real-time Virtual Sonography, and *7 4Dshading are registered trademarks or trademarks of Hitachi, Ltd. in Japan and other countries. References 1) Akifumi Sako, et al.: Development of Ultrasonic Transducer Mappie with cmut Tsechnology, MEDIX, 51: 31-34, ) Masaru Maruyama et al.: Does the Changing Position at Abdominal Ultrasonography Reduce the Physical Load of the Ultrasonographer? Second Report 3) Ultrasound Equipment and Safety Committee, The Japan Society of Ultrasonics in Medicine. Recommendations for Sonographers to Work Safely, Comfortably and Healthfully - Equipment and working environment to prevent work-related musculoskeletal disorders and eye disorders ) 2016 Cancer Statistics and Prediction: National Cancer Research Center Cancer Information Service 5) Koji Waki et al.: Development of a New Generation of Breast Real-time Tissue Elastography in Diagnostic sultrasound System. MEDIX, 65: 32-36, ) Akiko Tonomura et al.: Development of Strain Histogram Measurement Function and Clinical Applications in Hepatic Region. MEDIX, 54: 37-41, ) Fujimoto K, et al.: Novel image analysis method using ultrasound elastography for noninvasive evaluation of hepatic fibrosis in patients with chronic hepatitis C. Oncology, 84 (suppl 1): 3-12, ) Teruyuki Sonoyama et al.: Development of Shear Wave Measurement with a Reliability Index. MEDIX, 63: 40-44, ) Yada N, et al.: A newly developed shear wave elastography modality: With a unique reliability index. Oncology, 89 (suppl 2): 53-59, ) Liver Cancer White Paper 2015: Japan Society of Hepatology 11) Arai O, et al.: Integration Computer Tomography in Ultrasound Diagnosis Named Virtual Sonography, 2003 Scientific Assembly and Annual Meeting Program of Radiological Society of North America, p.807, 9424IMA-i, ) Azusa Sakamoto et al.: RFA Using 3D Sim-Navigator: a Novel Application Based on RVS. MEDIX, 64: 14-18, ) Hirooka M, et al.: Usefulness of a New Three-Dimensional Simulator System for Radiofrequency Ablation. PLoS One Feb 4; 11 (2). 14) Masahiro Ogino et al.: High Quality 3D Image Processing Technology for Diagnostic Ultrasound System -4Dshading- Hitachi Review VOL.96: ) Wada Y, et al.: Simultaneous Doppler Tracing of Transmitral Inflow and Mitral Annular Velocity as an Estimate of Elevated Left Ventricular Filling Pressure in Patients With Atrial Fibrillation. Circulation 10 MEDIX VOL.67 XX-E242