SWE in PLACENTAL DYSFUNCTION

Abstract

Objectives—The aim of this study was to determine whether shear wave elastography of the placenta differs between normal pregnancies and pregnancies complicated by preeclampsia between 20 and 23 weeks’ gestation.

Methods—A prospective study was performed with 204 consecutive singleton pregnancies that had routine anomaly scanning between 20 and 23 weeks’ gestation. One hundred twenty-nine of these patients were examined with shear wave elastography; 101 women who had clinically normal pregnancies with normal fetal biometric measurements and normal deliveries without any perinatal complications formed group A, and 28 women who had a clinical diagnosis of early-onset preeclampsia before anomaly scanning formed group B. Women with either posterior placentations (n = 63) or other obstetric disorders (n = 12) were excluded from the study.

Results—Shear wave elastographic values for group B were significantly higher than those for group A (P < .05). No statistically significant difference was found between the elasticity values measured at the center or edge of the placenta (P > .05).

Conclusions—Shear wave elastography differentiates between the placental elasticity of normal pregnancies and pregnancies complicated by preeclampsia when performed during the second trimester. As a new method for tissue characterization, shear wave elastography is useful for evaluation of placental function and can be used as a supplement to existing methods for prediction of preeclampsia.

METASTATIC CERVICAL LYMPH NODES on V T I [ARFI]

Abstract

Objectives—The purpose of this study was to investigate the clinical usefulness of acoustic radiation force impulse elastography for the differential diagnosis of cervical lymph nodes.

Methods—Virtual touch tissue imaging (Siemens Medical Solutions, Mountain View, CA) was analyzed in 81 patients (mean age, 46.6 years; range, 5–82 years) with 81 lymph nodes (45 metastatic nodes and 36 benign nodes).

Results—Most benign lymph nodes were slightly darker or the same in brightness compared with surrounding tissue, whereas most metastatic nodes were obviously darker. The mean area ratio of benign lymph nodes ± SD (1.05 ± 0.15) was statistically lower than the mean area ratio of metastatic lymph nodes (1.39 ± 0.20; P < 0.001). The area ration cutoff level for metastatic lymph nodes was estimated to be 1.16. With the use of a receiver operating characteristic curve with this cutoff value, the area ratio predicted malignancy with sensitivity of 91.1%, specificity of 83.3%, and an area under the curve of 0.925.

 

Conclusions—Acoustic radiation force impulse imaging is feasible for cervical lymph nodes. The Virtual Touch tissue imaging technique can complement conventional sonography, thereby making it easier to diagnose cervical lymph nodes.

Clinical Application of Musculoskeletal Ultrasound in Rheumatology in Taiwan

Yu-Fen Hsiao

Department of Internal Medicine, Chu Shang Show Chwan Memorial Hospital, Nantou, Taiwan

Ko-Jen Li

Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan

Diagnosis of rheumatic diseases is difficult due to diverse symptoms that can involve the bone, joints, muscles, tendons, blood vessels, or nerves. In the past, physicians made diagnoses based on history-taking, physical examinations, serological tests, and X-rays. However, difficulties in diagnosing rheumatic diseases arose from limitations in the sensitivity and specificity of serological tests and X-rays.

Magnetic resonance imaging (MRI) has a high sensitivity for detecting tiny inflammatory or destructive changes, which can help physicians in early diagnosis or in the monitoring of disease progression. However, MRI has a number of disadvantages, including its expense, time required, and its limited use in evaluating renal function, which hinder the use of MRI in routine practice. In contrast to MRI, musculoskeletal ultrasound (MSUS) has the advantage of being able to provide convenient, fast and real-time images for early diagnosis and routine follow-up [1]. In evaluations of soft-tissue lesions, MSUS and MRI are more sensitive than plain radiography and computed tomography. MSUS has the advantages of being non-radioactive, inexpensive, portable, and repeatable. It can provide high-resolution, power Doppler, real-time imaging of articular, periarticular and soft-tissue structures in the evaluation of rheumatologic disease. Furthermore, ultrasound-guided procedures allow for better assessment of target lesions with minimal injury to adjacent tissues such as nerves or blood vessels [2]. There is growing evidence to show that MSUS can play a more important role in the diagnosis and treatment of rheumatic diseases.

Spondyloarthropathies are composed of five diseases with similar rheumatic presentations, including ankylosing spondylitis, psoriatic arthritis, reactive arthritis, spondylitis associated with inflammatory bowel disease (IBD) and undifferentiated spondyloarthropathy. Enthesitis is one of the most common features of spondyloarthropathies. However, the diagnosis is difficult to make due to lack of clinical awareness and there being no standard method for evaluation in the past. MSUS is considered a good tool for evaluating enthesitis, with a high sensitivity and specificity. There are many sonographic quantitative scoring systems for enthesitis evaluation, including the Glasgow Ultrasound Enthesitis Scoring System (GUESS), Mander Enthesitis Index (MEI), and the Madrid Sonographic Enthesitis Index (MASEI) [[3], [4], [5]]. In this issue of the Journal of Medical Ultrasound, Hsiao et al report a pilot study using GUESS to evaluate enthesitis in patients with and without IBD [6]. Subclinical enthesopathy with higher GUESS scores were found in patients with IBD. Thus, musculoskeletal involvement in IBD should not be overlooked by simple history-taking or clinical examinations. Further long-term MSUS follow-up is needed in IBD patients.

MSUS is more sensitive than plain radiography in the detection of synovial hyperplasia, effusion, bony erosions, and inflammation with emerging power Doppler signals, allowing earlier diagnosis of progressive rheumatoid arthritis. This is important as it is now possible to aim for low disease activity in rheumatoid arthritis in this era of biological agents. MSUS can be another tool to guide treatment other than clinical symptoms, laboratory examinations and radiography. Ultrasound is becoming a useful tool that is integrated into clinical practice and linked to decision-making [7].

According to Raftery et al, MSUS performed by a rheumatologist aided diagnosis of synovial and tendon inflammation and guided injections, while MSUS performed by a radiologist aided diagnosis of structural pathology [8]. It is essential for rheumatologists to acquire ultrasonography skills in order to improve patient care [9]. The accuracy of ultrasound examinations is operator-dependent and the technical capabilities of MSUS are a critical issue in the extensive application of MSUS in rheumatology practice. In this issue of the Journal of Medical Ultrasound, Chen et al present a study of MSUS and MRI in detecting full-thickness rotator cuff tears [10]. With arthroscopic findings as the gold standard, MSUS performed by a qualified rheumatologist has good sensitivity and accuracy in detecting full-thickness rotator cuff tears, with good agreement with MRI.

In Taiwan, MSUS was introduced to rheumatology 20 years ago. However, there remain barriers to the more widespread use of MSUS in daily practice because of equipment costs, heavy clinical load, long learning curve and certification requirements. The training programs on the use of MSUS in rheumatology were developed by the Taiwan Rheumatology Association (TRA) only in the last 7 years. In 2013, the director of the TRA, Professor Der-Yuan Chen, focused on integrating the training and certifications in the TRA and the Chinese Taipei Society of Ultrasound in Medicine (SUMROC). Due to his efforts, the MSUS certification program for rheumatologists was organized this year. We believe that more and more Taiwan rheumatologists will join the training programs and MSUS will become a useful tool in the daily practice of every rheumatologist.

© 2014 Published by Elsevier Inc.

Steatosis Using Controlled Attenuation Parameter

Quantitative Assessment of Steatosis in Liver Tissue Using Controlled Attenuation Parameter

Cheng-Kun Wu, Tsung-Hui Hu

Division of Hepato-Gastroenterology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan

Hepatic steatosis (or fatty liver) is a common histological finding in patients with metabolic syndrome, alcoholic hepatitis, or hepatitis C, or those who receive certain drugs such as steroids and amiodarone. The complication of hepatic steatosis in patients with other liver diseases such as hepatitis C leads to the progression of liver fibrosis and poor treatment response. Therefore, an accurate evaluation of hepatic steatosis is essential for clinical decision making and prognosis assessment. Abdominal ultrasonography is a highly accurate and commonly used tool for diagnosing fatty liver. The diagnostic criteria of this technique include the following: brightness contrast between the liver parenchyma and the right renal cortex; masking of the portal vein, hepatic vein, and gallbladder wall; and ultrasound attenuation in deep liver tissues. However, ultrasound has low sensitivity in diagnosing mild steatosis and is prone to the operator’s subjective opinion. Although computed tomography and magnetic resonance imaging play a certain role in diagnosing fatty liver, these techniques are limited by availability and radiation exposure. Computed tomography is suitable only for detecting steatosis with >30% fat accumulation. Although magnetic resonance imaging offers outstanding accuracy, it is less suited for regular screening for fatty liver because it is both complex and expensive. Currently, the gold standard for steatosis assessment is liver biopsy; however, it is invasive, costly, prone to sampling bias, and risks potential serious complications. Furthermore, in the clinical setting, repeated biopsies are not a feasible method for following up on the status of steatosis. To overcome these limitations, Fibroscan (® 502 Touch by Echosens (Paris, France)), a technology based on liver fibrosis, has been developed.

The measurement of ultrasound attenuation during transmission through biological tissues has multiple useful biomedical applications. Ultrasound attenuation, the energy loss when the sound wave passes through a medium, depends on: (1) the frequency of the ultrasound; and (2) the nature of the transmission medium. The standard ultrasound attenuation rates at 3.5 MHz in different human tissues are as follows: 175–630 dB/m in fat, 40–70 dB/m in liver, 315–385 dB/m in tendons, and 105–280 dB/m in soft tissues. Based on ultrasound attenuation principles and the effect of fat on attenuation, researchers developed a new method, named controlled attenuation parameter (CAP), to quantify the degree of steatosis in liver tissue [1]. This technology uses Vibration-Controlled Transient Elastography (VCTE), which emits ultrasound at a fixed center frequency of 3.5 MHz and traces the velocity of shear waves to measure liver firmness. In addition, CAP uses the frequency data collected from the same examination area to assess the total attenuation of the ultrasound signal, including the paths from and to the probe. The result is expressed in dB/m, ranging from 100 dB/m to 400 dB/m (a higher value represents a larger proportion of steatosis). The CAP technology is noninvasive, is easy to use, and provides real-time surveillance. Furthermore, because the procedure can monitor an area 100 times that of liver biopsy, it eliminates operator sampling bias. Fibroscan allows the clinician to evaluate and quantify steatosis while assessing fibrosis, thus facilitating post-treatment comparison through follow ups.

Myers et al [2] analyzed 153 patients who received liver biopsy and CAP-coupled Fibroscan simultaneously. They found that patients with a higher degree and proportion of steatosis confirmed by liver biopsy also had higher CAP scores. A recent large-scale study (comprising 5323 tests) found CAP scores associated with clinical disease presentation and blood test values. Researchers found that patients with fatty liver-triggering conditions such as metabolic syndrome, alcoholism, hypertriglyceridemia, large abdominal circumference, diabetes or hypertension, and high body mass index (>30 kg/m²) had increased CAP values accordingly. CAP areas under the receiver operating characteristic curve were 0.79 [95% confidence interval (CI), 0.74–0.84; p < 0.001], 0.84 (95% CI, 0.80–0.88, p < 0.001), and 0.84 (95% CI, 0.80–0.88, p < 0.001) in patients with >10%, >33%, and >66% steatosis, respectively [3]. Other clinical studies also showed CAP examination to be free from operator bias. In a prospective study, two independent operators performed CAP examinations on 118 patients. The results revealed good consistency between the CAP data from the two operators, with an intraclass correlation coefficient of 0.84 (95% CI, 0.77–0.88) [4]. In addition, CAP can be used to diagnose fatty liver regardless of etiology. One study recruited 146 patients with chronic hepatitis B, 180 with chronic hepatitis C, and 63 with nonalcoholic fatty liver; all 389 patients received liver biopsy and CAP examination. CAP showed areas under the receiver operating characteristic curve of 0.683, 0.793, and 0.841 in chronic hepatitis B patients with ≥6 %, >33%, and >66% steatosis, respectively. In addition, the accuracy of diagnosing fatty liver did not differ significantly between groups [5].

Fibroscan coupled with CAP shows promise as a noninvasive tool for assessing liver fibrosis and steatosis. Specifically, as this technology provides longitudinal data, it can be effectively used to evaluate treatment outcomes and prognosis in patients with chronic viral hepatitis, nonalcoholic fatty liver disease, or alcoholic hepatitis, as well as other chronic liver diseases.

© 2014 Published by Elsevier Inc.

Detecting Rotator Cuff Tears in Rheumatoid Arthritis: US in Comparison to MRI

Diagnostic Utility of US for Detecting Rotator Cuff Tears in Rheumatoid Arthritis Patients: Comparison with Magnetic Resonance Imaging
Der-Yuan Chen, Howard Haw-Chang Lan, Kuo-Lung Lai, Hsin-Hua Chen , Chan-Pein Chen

ABSTRACT

Background
Ultrasonography (US) is being increasingly used in clinical practice to detect rotator cuff tears (RCTs) in patients with rheumatoid arthritis (RA) who have shoulder pain. The major aim of this study was to determine the diagnostic utility of US and magnetic resonance imaging (MRI) for detecting RCTs in patients with RA who have persistent shoulder pain.

Patients and methods 
With standardized procedures, US and MRI examinations of the shoulder were performed in 36 patients with RA who had persistent shoulder pain prior to arthroscopic intervention. Within 1 month after US and MRI examination, arthroscopic repair was performed. Arthroscopic findings were used as the gold standard for the diagnosis of RCTs.

Results 
Full-thickness RCTs in 28 patients with RA (77.8%) and partial-thickness RCTs in eight patients (22.2%) were identified using arthroscopic inspection. With arthroscopic findings as the gold standard, the sensitivity and accuracy of US in detecting full-thickness RCTs were 92.9% and 89%, respectively, whereas those for MRI were 96.4% and 90%, respectively. In detecting partial-thickness RCTs, the sensitivity and accuracy were 62.5% and 75.0%, respectively, for US, in contrast with 87.5% and 88%, respectively, for MRI. The overall agreement between US and MRI was 89.3% in detecting full-thickness RCTs and 75.0% in detecting partial-thickness RCTs. US demonstrated levels of sensitivity similar to that of MRI in detecting posterior recess synovitis, tenosynovitis, and subacromial-subdeltoid bursitis.

Conclusions

With a good agreement with MRI, US was shown to be a highly sensitive and accurate imaging modality in detecting full-thickness RCTs for patients with RA who have shoulder pain, but appeared to have lower sensitivity in detecting partial-thickness RCTs compared with MRI.

US Elastography and Achille Tendon

The Achilles is the largest and most frequently injured tendon, and the incidence of injury increases with age. A large-scale study in the literature found that runners older than 40 were more than twice as likely to injure the Achilles tendon and calf muscle, most often as Achilles tendinopathy and gastrocnemius muscle strains, said presenter Laura Chernak Slane, PhD.

Several studies have examined the biological changes in the tendon that occur from aging. Researchers found a variety of factors that occurred at different scales in the tendon, including an increase in elastin content, a decrease in collagen fibril diameter, and a decrease in fascicle sliding.

"But it's challenging to understand how these microscopic changes affect whole-scale tendon mechanics," she said.

In recent years, there's been a lot of emphasis in the biomechanics community on using ultrasound-based methods to track anatomical landmarks while a subject undergoes different types of loading patterns, Slane said.

Conflicting literature results

These in vivo observations in the literature have yielded conflicting results, however. Some studies found that tendon strain increases with age, while others found that tendon strain decreases with age. Another study found that tendon stiffness was the same between age groups.

"So it's unclear what is really happening as we age," she said. "We hypothesize that this might be due to the fact that oftentimes these anatomical landmark-tracking approaches look at large portions of the Achilles tendon, all the way from the calcaneus to the gastrocnemius muscle tendon junction -- really large regions."

The group was interested in learning whether there were spatial variations among different tendon regions that might explain the conflicting results, Slane said. The researchers used a commercially available imaging technique (supersonic shear imaging, SuperSonic Imagine) to evaluate tendon mechanical properties at high resolution.

With the quantitative technique, a focused ultrasound beam induces shear waves in the underlying tissue; the shear waves are then tracked as they propagate throughout the tissue via collection of ultrahigh-frame-rate data. Average shear-wave speeds are calculated and displayed for manually selected regions of interest on the ultrasound image.

"Shear-wave speed is an important mechanical characteristic because it relates to the elastic modulus of a tissue," she said. "As shear-wave speed increases, we expect an increase in tissue stiffness."

The study included 10 healthy young adults (seven females and three males) with an average age of 25 ± 4 years, along with 10 healthy middle-aged adults (five females and five males) with an average age of 49 ± 4 years.

Shear-wave speed (SWS) was measured at three Achilles tendon areas (the free tendon, the soleus aponeurosis, and the medial gastrocnemius aponeurosis) at rest and at dorsiflexed and plantarflexed angles.

Significant variations

Shear-wave speed varied significantly according to imaging location; the free tendon had the highest speeds. In addition, ankle posture significantly affected SWS; speed progressively increased with ankle dorsiflexion along the whole length of the tendon, the researchers found.

There was only one significant age-related difference: a significant reduction in shear-wave speed for middle-aged adults in the gastrocnemius aponeurosis, which "corresponds with the region where calf muscle strains are thought to occur," Slane said. "A lot of MR images show them originating near the muscle-tendon junction."

A significant inverse relationship was seen between resting gastrocnemius aponeurosis SWS and age (R2= 0.34, p < 0.01), and a similar relationship was seen in the gastrocnemius aponeurosis in the dorsiflexed posture (R2 = 0.55, p < 0.01).

Because it's difficult to distinguish the relative contributions of different factors behind these tendon changes, the researchers are now collaborating with a team from the University of Virginia to build a musculoskeletal model to help them interpret the study results, Slane told AuntMinnie.com.

She noted, however, that the significant variation in shear-wave speeds found in different regions of the Achilles "emphasizes that when we're looking at different studies or when we're using it clinically, it's really important that we think about what region we're using and how we're comparing that."

Postural angle also significantly affected SWS, so it's important to report and consider angle and posture with these studies, she added.

The results also suggest that different portions of the Achilles tendon may be changing in different ways.

ULTRASOUND ANATOMY of LUNG and UPPER RESPIRATORY TRACT

For Medical Tan tao University students.

Xin vào địa chỉ sau để download (PDF file)

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O-mode ULTRASOUND in DEVELOPMENT

CHICAGO — The new O-mode form of ultrasound, which improves visualization behind structures and eliminates the need for beam formation, also weighs and costs less than conventional ultrasound, according to researchers presenting here at the Radiological Society of North America 100th Annual Meeting.

"We were quite impressed that, for the little bit of work that we did, we got such images," said Richard Barr, MD, from the Northeast Ohio Medical University in Youngstown. "The technology is actually not extremely complex," he explained, and said he expects that the small hand-held O-mode device will be available next year.

Dr. Barr presented a proof-of-concept study that confirmed that O-mode imaging is possible in a clinical setting.

The beam focuser required for traditional B-mode ultrasound imaging is considered to be important, but can lead to many of the limitations and artifacts seen in conventional scans. In contrast, the O-mode technique does not require a beam focuser.

The novel technique mimics a "single transducer lateral motion" along a known trajectory. This allows the Doppler effect to be evoked artificially from the "moving" transducer.

The result is an echo in different radiofrequency shifts that comes from the different scatterers located at the same depth but at different lateral positions, Dr. Barr explained. The technique makes it possible to visualize a Doppler shift between the Z particles.

O-mode provides constant lateral resolution that is independent of depth of penetration. It therefore significantly decreases the shadowing from small pockets of gas, allowing for the use of new imaging windows.

It also allows for exact lateral localization by exchanging the traditional ultrasound focusing procedure along the line of sight with signal processing of frequency-modulated signals that come from each depth.

Proof of Concept

To test the effectiveness of the O-mode method, Dr. Barr and his team used the technique to scan various organs of 10 patients.

When the images, which received very little post-processing, were reviewed by a board-certified radiologist, all were deemed to visualize deep structures at least as well as conventional B-mode ultrasound.

In addition, O-mode imaging can be performed in real time at 30 to 40 frames per minute, a rate typical of that seen with other systems, Dr. Barr pointed out.

"That's interesting," said session moderator Jason Stafford, PhD, from the University of Texas MD Anderson Cancer Center in Houston. He told Medscape Medical News that he is eager to read more about the technique.

The next step will be to "implement a small device that will be for the market," said Mati Shirizly, PhD, chief executive officer of Orcasonix, the company that will be manufacturing the O-mode ultrasound. The small device will likely retail for approximately $5000.

"Eventually, we will want to put this technology into a high-end system," Dr. Shirizly told Medscape Medical News. He said he thinks the technique will be particularly useful for imaging the hearts of obese patients.

However, during his presentation, Dr. Barr acknowledged that the O-mode technique still requires improved contrast resolution and improved image processing. Because the O-mode does not yet include image processing, it is difficult to truly compare it to conventional ultrasounds. "At this point, it really is hard to do a comparison of apples to apples. It really is apples to oranges," he said.

This study received funding by Orcasonix, the company that will manufacture the O-mode ultrasound. Dr. Barr is a consultant at Siemens AG. Dr. Stafford has disclosed no relevant financial relationships. Dr. Shirizly is a shareholder at Orcasonix.

Radiological Society of North America (RSNA) 100th Annual Meeting: Abstract SSA21-09. Presented November 30, 2014.

Orcasonix Unveils Innovative Ultrasound Technology Built on Cephasonics cQuest Family of Ultrasound Systems

Visit Cephasonics at RSNA 2013 in Hall B, Booth 8522

Monday, December 2, 2013 - 06:00

Chicago, December 2, 2013—Cephasonics, a technology-innovation leader with a game-changing embedded-ultrasound platform, and Orcasonix, an innovative ultrasound company specializing in imaging systems with depth-independent resolution, today disclosed details of the Cephasonics design-in. Orcasonix used the Cephasonics cQuest Cicada™ platform to develop its first prototype imaging system, the Orca™-1, and plans to commercialize the system in 2014 and go to volume production with the just announced cQuest Dragonfly™ system. Orcasonix will be showcasing its new technology in Cephasonics’ booth at RSNA 2013 held here in Chicago from December 1-6.  Visitors can also see Cephasonics’ latest technology, including Dragonfly.

According to Mati Shirizly, CEO of Orcasonix, “Cephasonics’ unique business model and flexible cQuest Ultrasound™ hardware/software architecture provided us with a fast way to prove our technology, develop a prototype, and conduct initial clinical trials.” He said that his company’s innovative imaging techniques will dramatically improve the scanning of challenging patients, including general abdominal imaging of obese, overweight patients.

“The Orcasonix team achieved a major breakthrough in ultrasound imaging and we are pleased to partner with them both in demonstrating the unique capabilities of their depth-independent resolution imaging system and supporting their production ramp with our solutions,” said Richard Tobias, CEO of Cephasonics.

Orcasonix developed a new ultrasound imaging system with depth-independent resolution that uses a novel patented approach of generating CT-like images from sound echoes. The technology enables an extremely low cost hardware implementation with a virtually unlimited number of channels at a fraction of the cost of current systems. Signal and image processing is extremely efficient, thus significantly reducing the cost of the ultrasound system’s computer sub-system. The Orca-1 will be the first in a planned family of high-quality, cost-efficient imaging systems.

About Cephasonics

A technology-innovation leader with a game-changing embedded-ultrasound platform, Cephasonics provides a complete range of cQuest™-based technology, systems and components that increase the performance, lower the power and accelerate time-to- market of ultrasound devices. The company’s cQuest Ultrasound API™ software is the catalyst for customer innovations that are spurring a revolution in ultrasound from image-guided procedures to ultrasound as an appliance. Launched with a management buyout in March 2012 and headquartered in Santa Clara, Calif., Cephasonics’ technology, including its AutoFocus™ beamforming technology, has won multiple industry awards for innovation. Additional information about Cephasonics can be found at www.cephasonics.com.

About Orcasonix

An innovative ultrasound imaging company that has developed a new ultrasound-imaging platform with depth-independent resolution, Orcasonix was established in 2011 and is based in Netanya, Israel. Its first product has started clinical trials and others are in early stages of development. Additional information about Orcasonix can be found at www.orcasonix.com

# # #

cQuest, cQuest Ultrasound, cQuest Ultrasound API, cQuest Cicada, cQuest Dragonfly, and AutoFocus are trademarks of Cephasonics.

Orca-1 is a trademark of Orcasonix.

Cephasonics
160 Saratoga Ave, Suite 180
Santa Clara, CA 95051
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ARFI DỰ ĐOÁN GIAI ĐOẠN XƠ HÓA GAN Ở GAN NHIỄM MỠ KHÔNG DO RƯỢU [NAFLD]

ĐÁNH GIÁ VAI TRÒ CỦA KỸ THUẬT GHI HÌNH XUNG LỰC BỨC XẠ ÂM (ARFI)

TRONG DỰ ĐOÁN GIAI ĐOẠN XƠ HÓA GAN TRÊN BỆNH NHÂN

BỊ VIÊM GAN NHIỄM MỠ KHÔNG DO RƯỢU

              Trần Thị Khánh Tường ¹, Hoàng Trọng Thảng ², Võ Thị Xuân Hạnh³

                              1, 3 Trường Đại học Y khoa Phạm Ngọc Thạch

 2 Trường Đại học Y Dược Huế

TÓM TẮT

Tổng quan và mục tiêu :  Xung lực bức xạ âm (ARFI) là một kỹ thuật mới không xâm lấn, đơn giản dùng để đánh giá các giai đoạn xơ hóa gan trong bệnh gan mạn. Một số nghiên cứu trước đây cho thấy rằng ARFI là phương tiện đầy hứa hẹn trong đánh giá xơ hóa gan ở bệnh nhân bị bệnh gan nhiễm mỡ không do rượu (NAFLD). Nghiên cứu này nhằm mục đích xác định giá trị chẩn đoán của ARFI trong dự đoán giai đoạn xơ hóa ở những bệnh nhân bị viêm gan nhiễm mỡ không do rượu (NASH).

Đối tượng và phương pháp nghiên cứu : Nghiên cứu được thực hiện trên 51 bệnh nhân bị NASH. Tất cả bệnh nhân đều được sinh thiết gan để đánh giá xơ hóa gan và thực hiện kỹ thuật ARFI. Các giá trị ngưỡng được xác định bằng cách phân tích đường cong ROC.

Kết quả : Xơ hóa gan xác định bằng giải phẫu bệnh được đánh giá bằng thang điểm Metavir, F0: 8 trường hợp, F1: 29 trường hợp, F2: 10 trường hợp, F3: 4 trường hợp. ARFI có tương quan khá chặt với mức độ xơ hóa (Spearman rho: 0.44, p <0.05). Diện tích dưới đường cong ROC (AUROC) 0.75 (khoảng tin cậy 95%: 0.60-0.90) đối với ≥ F2 và 0.78 (0.53-0.99) đối với F3. Giá trị ngưỡng của vận tốc sóng biến dạng (SWV) như sau: ≥ 1,29 m/s cho ≥ F2 (độ nhạy 64.3%, độ đặc hiệu 83.8%, PPV 60% và NPV 86.1%); ≥ 1,38 m/s cho F3 (độ nhạy 75.00%, độ đặc hiệu 89.4%, PPV 57.5% và NPV 97.7%).

Kết luận: SWV của ARFI tương quan với mức độ của xơ hóa gan. Kỹ thuật ARFI có độ chính xác khá tốt, độ chuyên và NPV cao trong đánh giá xơ hóa gan đáng kể và xơ hóa nặng  ở những bệnh nhân bị NASH. Kỹ thuật này nên thực hiện thường qui cho các bệnh nhân bị NASH để loại trừ xơ hóa gan đáng kể và xơ hóa gan nặng.

Từ khóa: xơ hóa gan, độ cứng của gan, bệnh gan nhiễm mỡ không do rượu (NAFLD), viêm gan nhiễm mỡ không do rượu (NASH), kỹ thuật xung lực bức xạ âm (ARFI)

ABSTRACT

ASSESSING THE ROLE OF ACOUSTIC RADIATION FORCE IMPULSE IMAGING FOR PREDICTION OF STAGING OF LIVER FIBROSIS

IN PATIENTS WITH NONALCOHOLIC STEATOHEPATITIS

Background / Objectives: Acoustic radiation force impulse (ARFI) is a novel non-invasive technology for the assessment of stages of liver fibrosis in chronic hepatic disease. Some studies previously reported that ARFI is a promising method for assessing liver fibrosis in patients with NAFLD/NASH. This study aimed to validate the diagnostic usefulness of ARFI for prediction of staging of liver fibrosis in patients with NASH.

Patients and Methods: The study was carried out on 51 patients with NASH. All of patients underwent a liver biopsy for histological assessment of liver fibrosis and ARFI elastography. Cut-off values were determined using receiver-operating characteristic (ROC) curves.

Results: Histological liver fibrosis was evaluated by Metavir scoring; F0: 8 cases, F1: 29 cases, F2: 10 cases and F3: 4 cases. ARFI quantification correlated significantly with the fibrosis stage (Spearman rho: 0.44, p <0.05). The areas under the ROC curves (AUROC) were  0.75 (95% confidence intervals: 0.60-0.90) for ≥F2 and 0.78 (0.53-0.99) for F3. The cut-off values of the shear wave velocity (SWV) were as follows: ≥1.29 m/s for ≥F2 (sensitivity 64.3%, specificity 83.8%, PPV 60% and NPV 86.1%), ≥ 1.38 m/s for F3 (sensitivity 75%, specificity 89.4%, PPV 57.5%, NPV 97.7%).

Conclusions: Increasing ARFI velocities correlate with high degree of liver fibrosis. ARFI has quite good accuracy and high specificity, NPV for prediction of significant and advanced fibrosis in patients with NASH. The method should be employed routinely in the workup of patients with NASH to exclude the presence of significant and advanced liver fibrosis.

Key words: liver fibrosis, liver stiffness, non-alcoholic fatty liver disease (NAFLD), nonalcoholic steatohepatitis (NASH), acoustic radiation force impulse imaging (ARFI). 

A B U S and H H U S

Purpose: The purpose of this study was to prospectively evaluate the interobserver agreement
on lesion characterization and the final assessment of automated whole breast ultrasonography
(ABUS) images.
Methods: Between March and August 2012, 172 women underwent bilateral ABUS before
biopsy guided by handheld ultrasonography (HHUS) and mammography. A total of 206 breast
lesions were confirmed histopathologically by biopsy. Three-dimensional volume data from ABUS
scans were analyzed by two radiologists without the knowledge of HHUS results or patient
clinical information. The two readers described the type, shape, orientation, margin, echogenicity,
posterior acoustic features, and categorization of the final assessment of detected breast lesions.
Kappa statistics were used to analyze the described characteristics of the breast lesions detected
by both of the two readers.
Results: Of the 206 histopathologically confirmed lesions, reader 1 detected 166 lesions and
reader 2 detected 150 lesions. A total of 145 lesions were detected by both readers using ABUS
images. There was substantial agreement on shape (κ=0.707), and moderate agreement on type,
margin, mass orientation, echogenicity, and posterior acoustic features (κ=0.592, 0.438, 0.472,
0.524, and 0.541, respectively). Breast Imaging Reporting and Data System final assessment
values yielded a kappa value of 0.3971 when category subdivisions 4A, 4B, and 4C were
included. With respect to the C2, C3, C4, and C5 categories, the interobserver agreement was
moderate (κ=0.505).

Conclusion: ABUS is a promising diagnostic tool with a good interobserver agreement,
comparable to that of HHUS.
Keywords: Breast; Ultrasonography; Observer variation