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1. Introduction1.1 Background to the development

With the expansion in the number of disciplines using ultrasound technology in clinical practice, diagnostic ultra-sound systems are experiencing increased market growth, with a growth forecast of 3% to 5% between 2015 and 2018. Hitachi’s growth strategies include “Aiming for No.1 position in Global Market Share” and a “Leading Company Providing Clinical Innovation”.

1.2 Purpose of the development

Led by clinical demands in the diagnostic ultrasound mar-ket, Hitachi is developing unique applications in the three main clinical areas: radiology, gynecology, and cardiovascu-lar. The ARIETTA*1 850, a premium class diagnostic ultra-sound 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 Work-flow”, and “Your Application”, providing a premium class diagnostic ultrasound system that meets users’ expectations in all aspects of image quality, operability, and providing ad-vanced applications.

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.

Development of the diagnostic ultrasound system ARIETTA 850

1) Products R&D Division 1, Diagnostic R&D Division, Hitachi, Ltd. Healthcare Business Unit2) 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

Key Words: Key Words: 4G CMUT, eFocusing, RVS, RTE, SWM

Tetsuo Watanabe 1) Akifumi Sako 2)

Takehiro Tsujita 1) Nobuhiko Fujii 1)

Teruyuki Sonoyama 2) Toshinori Maeda 2)

Kazuhisa Kozai 3)

Hitachi, Ltd. Healthcare Business Unit (HHBU) was formed as the healthcare section of Hitachi group in April 2016.

ARIETTA*1 850 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.

Technical Report

Figure 1: ARIETTA 850

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2. Pure ImageReturning to diagnostic ultrasound basics, we have

sought improved performance in the three major aspects of imaging – spatial, contrast, and temporal resolution – ad-vancing fundamental performance using Pure Symphonic Architecture technology (Figure 2).

2.1 Electronic convex probe “C252”A single-crystal piezoelectric material with an electrome-

chanical coupling coefficient of more than 90% has been im-plemented 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.

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).

These technologies support the increase in throughput of abdominal examinations necessary in the modern health-care environment, improving the comfort of both examiner and patient, whilst enhancing exam efficiency.

2.2 4G CMUT (CMUT Linear SML44 probe)

Hitachi was the first company to put the CMUT (Ca-pacitive 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 con-ventional transducers such as those using piezoelectric ce-ramics, 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.

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 width1) (Figure 6).

Frequency

Conventional transducer

Transducer sensitivity

CMUT chip CMUT cell

Vibrating membrane (insulating material) High

voltage

*nm=1/10 9 mCross section of CMUT cell Vacuum cavity (Height ~ nm*)

Frequency

HighMidLow

4G CMUT (2-22MHz)

Transducer sensitivity

Figure 3: C252 and its frequency spectrum

Figure 5: Structure of the 4G CMUT CMUT chip is packed with many CMUT cells in a matrix array

Figure 6: 4G CMUT frequency spectrum

Figure 4: C252 intercostal scanning

ActiveBackend

OLEDMonitor

VariableBeamformer

Probes /Frontend

OLED Monitor: Organic Light Emitting Diode Monitor

Figure 2: Pure Symphonic Architecture

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2.3 “HI Framerate” and “eFocusing” realized by the Variable Beamformer

“HI Framerate”ARIETTA 850 is equipped with “HI Framerate,” a mul-

tidirectional 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).

“eFocusing”In beam forming during reception for diagnostic ultra-

sound 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 transmis-sion 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 recep-tion 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 creat-ed. 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 simul-taneous 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

9 (c). This process of synthesis can be interpreted as trans-mission 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 synthe-sized from multiple transmissions contribute to an improved signal-to-noise ratio and thus improved penetration. Exam-ples 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 elimi-nates the need to set a transmission focus depth. Therefore, in addition to providing high-quality B-mode images with ex-cellent penetration, it also contributes to improved workflow by reducing examination time.

Transducer elements

Transmission focus point

Deterioration of lateral resolution

Transmission beam shape

Synthesis

Reception beam field (Formed by multidirectional simultaneous reception)

Transmission

(a) Reception field and scattering point ● in each transmission

(b) B-mode images of scattering point ● formed by a single transmission ●

(c) B-mode image by “eFocusing”

Figure 8: Conventional beam transmission

Figure 9: Effects obtained by “eFocusing”

Figure 7: “HI Framerate” Off (left) and On (right)

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2.4 High quality imaging achieved by the Active Back-end with a wide range of image quality parameter adjustments to meet the individual needs of exam-iners and patients.

Ultrasound diagnostic imaging can be examiner-depen-dent 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 port-folios, including the HI VISION, ProSound*2, and ARIETTA series, and are thus capable of of fering a wide range of image quality adjustments to provide images suited to each type of examination, ranging from quantitative to morpholog-ical (Figure 11).

〇 Qualitative evaluation: Images with a wide dynam-ic range, capable of visual-izing the detailed informa-tion of soft tissues.

〇 Morphological evaluation: Higher contrast, struc-ture-emphasized images for better understanding of morphology.

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 en-hancement. This allows improved spatial resolution, reduced blurring, and edge enhancement whilst maintaining conven-tional spatial compounding benefits.

・HI REZ*3+BCFThe BCF (Border Clear Filter) improves visibility of the

endocardial lining and valves in cardiovascular applications. Combined with HI REZ it provides superior definition result-ing in improved examination efficiency in cardiovascular and obstetric exams.

・Low Echo ReductionAdjusts low echo signals to provide image clarity with

minimum noise.

・Grayscale EnhancementAdjustment of both high and low grayscale echo signals

to optimize contrast with a single parameter, thereby contrib-uting to improved workflow.

2.5 Improvement of contrast resolution by organic EL monitor

B-mode, the abbreviation of Brightness mode, is the fun-damental 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 import-ant indicators for this grayscale performance is contrast res-olution. 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 de-picted by blocking the emission of light from each element, thereby achieving a high contrast ratio. Even in a high per-formance 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 dis-play monitor for diagnostic ultrasound systems.

3. Seamless Workflow3.1 Operating console

Ultrasound examinations are performed in real-time, most often with the examiner facing the patient, so simpli-fying operations and reducing the examination time brings benefits both to the examiner and patient. In abdominal ul-trasound, commonly used adjustments of Cine Search after Freeze, and Bodymark adjustment to indicate the region im-aged, are repeated for each recorded image. With a conven-tional 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 examina-tion (Figure 12).

Figure 10: “eFocusing” Off (left) and On (right)

Figure 11: Image parameter adjustments for qualitative evaluation (left) and image parameter adjust-ments for morphological evaluation (right)

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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 ac-cessing these controls is eliminated.

In ARIETTA 850, “L” and “R” switches have been added to “Enter” and “Undo”, enabling shortcuts for various com-plex functions, contributing to ease of use and reduced ex-amination times. (Figure 13).

3.2 System design to prevent Visual Display Terminals (VDT) syndromeCable management realized by Ergonomic design

Prevention of VDT syndromeThe ultrasound examiner can suffer physical stress when

examinations are performed with the body twisted into an unnatural posture2). 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 ex-

aminer to maintain an optimal working posture either in the seated or standing position (Figures 14 and 15).

Operating console: Moves up and down by 700-1000 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 Medicine3). 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 conven-tional models, transducer cables can get entangled when-ever 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 direc-tion 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

±25°

360°

224mm172mm

10°

700mm

1000mm

700mm

1000mm

Figure 12: Operating console layout

Figure 13: Operating console, “L” and “R” switches

Figure 17: Cables do not become entan-gled when the transducer is removed

Figure 14: Horizontal move-ment range

Figure 15: Vertical movement range Figure 16: Back and forth movement of the monitor

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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*4 880. 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 sam-ple gate position” is now possible by image recognition soft-ware. Machine learning techniques are employed to deter-mine 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 op-erator-dependent. These dif ferences between operators place an additional load on the radiologist or other clinicians during interpretation and reporting.

Protocol Assistant supports standardization by using pre-registered 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 proto-col. 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, ex-amination efficiency resulting in shorter exam times can be expected.

With ARIETTA 850, preregistration of protocols is sim-plified and routines performed on the system can be mem-orized as protocols. However, maximum flexibility is incor-porated 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 imag-es being unintentionally linked to the protocol.

Protocol Assistant contributes significantly to improving examination efficiency and quality and the ease of preregis-tration will increase its acceptance.

4. Your Application4.1 Breast elastography

Currently there are over 90,000 people with breast cancer in Japan. Predicted to be the most common cancer in wom-en4), 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 technol-ogy, Real-time Tissue Elastography*5 (RTE) in 2003, as a

Figure 18: Semi-automation of Simpson’s measurement

Figure 19: Automatic setting of sample gates for Dual Gate Doppler

Figure 20: Example of examination screen when using Protocol Assistant

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non-invasive ultrasound method for imaging tissue elasticity (stiffness). Today, it is in routine clinical use. Ongoing de-velopments have improved the simplicity, objectivity, and quantification in order to promote its widespread use5), 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 ef-fective 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

shear wave speed measurement method for liver elastogra-phy (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 progresses6). It has been reported that the LF Index correctly reflects the degree of liver fibrosis without influence from inflammatory processes7), 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. Howev-er, the propagation of the shear wave can be disrupted by an unsteady examiner’s hand, movements by the patient or vas-cular flow. Thus it is difficult to judge the validity of the mea-surement 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 measurement8). Clinical studies have shown that adopting only measurements in which VsN is over 50% improves Vs measurement accuracy9).

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 com-prehensively evaluating liver disease, adding functions for separately evaluating fibrosis and inflammation by the simul-taneous 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 declin-ing since then. Still, the annual number of deaths exceeds 30,000 people, making it a disease requiring serious control measures10). Radio Frequency Ablation (RFA) is one type of local treatment for liver cancer. With this minimally inva-sive surgery, an electrode needle placed within the tumor can thermally coagulate it with radio frequency waves. For ef fective 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

Automaticsetting

ROI movement

Figure 21: Seamless execution of ASR

Figure 22: Liver elastography modes Left: RTE, Right: SWM

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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 nee-dle, 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 posi-tion 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 RVS12)13). During RFA treat-ment, 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 simulat-ing 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.

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 ul-trasound even if there is some patient movement during the procedure.

In this way, RVS is evolving to keep pace with the advanc-es in RFA methods, contributing to the accuracy of liver can-cer 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 as-sessment, 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 technol-ogy “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 Ac-tive 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, de-tailed 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 func-tions.

・ 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 ad-vanced 4Dshading function adding shadowing to giving a

Figure 23: 3D Sim-Navigator display

Figure 24: 3D Sim-Navigator E-field display

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more realistic appearance of natural shadows and skin tex-ture, clarifying shape, and providing a 3D display giving a more natural impression. (Figure 25).

・ 4DshadingFlow function

Hitachi has adapted the 4Dshading technology for Dop-pler, 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 dis-play of blood flow in minute vessels.

・ 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.

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 com-pared 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 accu-racy. Hitachi has developed a measurement assist function which sets measurement points automatically once the char-acteristics 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 abdo-men. A detailed elliptical shape with reference to the edge in-formation is positioned and measurement points are set fol-lowing 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 bright-ness 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 final-ized. This measurement assist function with excellent opera-bility and measurement accuracy contribute to improving ex-amination efficiency for routine obstetric ultrasound checks.

4.6 Cardiac phase analysis by Dual Gate DopplerDual 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 el-evated left ventricular filling pressure in patients with sinus rhythm. In patients with atrial fibrillation, the simultaneous

Figure 25: Conventional 4Dshading (left) and new 4Dshading (right) (using CIRS fetal phantom)

Figure 26: 3D eflow image using conventional 3D (left) and 4DshadingFlow (right)

AB

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)

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recording of E and e’ using Dual Gate Doppler echocardi-ography and the analysis of T(E–e’), in addition to E/e’, im-proved the accuracy of evaluation of LV filling pressure15).

5. Conclusion

ARIETTA 850 provides customer values befitting a pre-mium class products in all aspects of “image quality”, “work-flow”, “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 Re-al-time Tissue Elastography, *6 Real-time Virtual Sonog-raphy, and *7 4Dshading are registered trademarks or trademarks of Hitachi, Ltd. in Japan and other countries.

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10) Liver Cancer White Paper 2015: Japan Society of Hepa-tology

11) Arai O, et al.: Integration Computer Tomography in Ul-trasound Diagnosis Named Virtual Sonography, 2003 Scientific Assembly and Annual Meeting Program of Ra-diological Society of North America, p.807, 9424IMA-i, 2003.

12) Azusa Sakamoto et al.: RFA Using 3D Sim-Navigator: a Novel Application Based on RVS. MEDIX, 64: 14-18, 2016.

13) Hirooka M, et al.: Usefulness of a New Three-Dimension-al Simulator System for Radiofrequency Ablation.PLoS One. 2016 Feb 4; 11 (2).

14) Masahiro Ogino et al.: High Quality 3D Image Pro-cessing Technology for Diagnostic Ultrasound System -4Dshading- Hitachi Review VOL.96: 62-67.

15) Wada Y, et al.: Simultaneous Doppler Tracing of Trans-mitral Inflow and Mitral Annular Velocity as an Estimate of Elevated Left Ventricular Filling Pressure in Patients With Atrial Fibrillation. Circulation

Figure 29 Cardiac phase analysis by Dual Gate Doppler