Siêu âm đàn hồi ARFI và siêu âm thường quy chẩn đoán phân biệt tổn thương đặc ở phổi (ARFI and Conventional US for Pulmonary Consolidation)

Siêu âm đàn hồi ARFI và siêu âm thường quy chẩn đoán phân biệt tổn thương đặc ở phổi

Bs Lê Thanh Liêm, Bs Nguyễn Thiện Hùng, Bs Phan Thanh Hải

Trung Tâm Y Khoa Medic, TP. Hồ Chí Minh, Việt Nam

Tóm tắt

Mục đích

Sử dụng kỹ thuật tạo hình xung lực bức xạ âm (ARFI - Acoustic Radiation Force Impulse Imaging) để khảo sát các tổn thương đặc phổi ở ngoại vi, kết hợp với siêu âm B-mode và Doppler để đánh giá khả năng của kỹ thuật ARFI trong chẩn đoán phân biệt các tổn thương này.

Đối tượng và phương pháp

Tổng cộng có 28 bệnh nhân tại Trung tâm Y khoa Medic từ tháng 10 năm 2008 đến tháng 12 năm 2012, trong đó có 21 bệnh nhân nam, tuổi từ 18 đến 79. 16 trường hợp viêm phổi thùy (57,1%), 6 trường hợp xẹp phổi (21,4%), 4 trường hợp ung thư phế quản (14,2%), 2 trường hợp lymphoma di căn phổi (7,1%). 6 trường hợp được làm siêu âm đàn hồi ARFI, bao gồm 3 trường hợp viêm phổi thùy và 3 trường hợp xẹp phổi. Mỗi trường hợp được đo ARFI (VTQ) 5 lần. Tất cả các trường hợp đã được chụp X-Quang phổi, xét nghiệm. Chụp cắt lớp vi tính đã được sử dụng trong các trường hợp chẩn đoán không rõ ràng (10 trường hợp, 35,7%). Phần mềm thống kê Medcalc được sử dụng để so sánh giá trị ARFI (V = m / giây) giữa hai nhóm.

Kết quả

16 trường hợp viêm phổi thùy, 9 trường hợp ở thùy dưới của phổi (87,5%), có hình tam giác (94%), bờ đều (68,7%), đồng phản âm với mô gan (25%), có khí ảnh nội phế quản (94%), có hình ảnh cây mạch máu (56%), phổ 3 pha kháng lực cao trên siêu âm Doppler (7/9 trường hợp). 6 trường hợp xẹp phổi, thường có hình tam giác (100%), bờ đều (83,3%), tăng âm (100%), cây mạch máu (2/6 trường hợp), phổ Doppler 3 pha kháng lực cao (2/2 ca), khí ảnh nội phế quản (50%). 4 trường hợp ung thư phế quản, thường có hình bầu dục (75%), bờ không đều (75%), giảm âm (100%), không có khí ảnh nội phế quản, có mạch máu đơn lẻ (4/4 trường hợp), phổ 1 pha kháng lực thấp (3/4 trường hợp). Lymphoma có hình tròn hay oval, phản âm kém giống nang và mạch máu đơn lẻ, không có khí ảnh nội phế quản. Vận tốc sóng biến dạng của viêm phổi thùy từ 2,06 đến 4,02 m/giây (trung bình=3,11 ± 0,99 m/giây) và của xẹp phổi từ 0,94 đến 1,93 m/giây (trung bình=1,52 ± 0,46 m/giây). Có sự khác biệt có ý nghĩa thống kê giữa hai nhóm với t = 2,896 (p = 0.034). Vận tốc sóng biến dạng của viêm phổi thùy cao hơn (cứng hơn)  vận tốc sóng biến dạng của xẹp phổi.

Kết luận

Đây là một nghiên cứu sơ bộ về siêu âm đàn hồi ARFI trong chẩn đoán phân biệt tổn thương đặc phổi ở ngoại vi, kết hợp với siêu âm B-mode và Doppler. Kết quả ban đầu cho thấy vận tốc sóng biến dạng ARFI của viêm phổi thùy cao hơn (cứng hơn)  vận tốc sóng biến dạng của xẹp phổi.

  Trong tương lai, cần nghiên cứu với số lượng lớn để xác nhận khả năng của kỹ thuật này và ứng dụng trong thực hành lâm sàng.

Tổng quan

Siêu âm phổi đã được biết đến từ lâu và có nhiều nghiên cứu và sách giáo khoa trên thế giới. Tuy nhiên, trong thực tế siêu âm ít được sử dụng trong chẩn đoán bệnh lý phổi, ngoại trừ chẩn đoán dịch màng phổi.

Viêm phổi thùy, xẹp phổi và u phổi là 3 bệnh lý ở phổi thường gặp và biểu hiện trên X-Quang là đám mờ với nét đặc trưng riêng, tuy nhiên nhiều trường hợp không thể phân biệt được rõ ràng. Trong trường hợp xẹp thùy phổi do tràn dịch màng phổi, X-Quang khó phát hiện do chồng lấp với hình mờ của dịch.

Siêu âm phổi chỉ thấy tổn thương ngoại vi phổi, nhưng khi thấy thì cung cấp rất nhiều thông tin về đặc điểm của tổn thương và có khi chấn đoán chính xác bản chất tổn thương. Trong viêm phổi thùy đã điều trị khỏi, hình ảnh tổn thương  phổi trên siêu âm mất đi trước khi mất trên X Quang.

Siêu âm Doppler màu cung cấp hình ảnh phân bố mạch máu trong tổn thương, Doppler phổ giúp phân biệt nguồn gốc mạch máu. Theo đó, phổ 3 pha kháng lực cao là đặc trưng của động mạch phổi và phổ 1 pha kháng lực trung bình là đặc trưng của động mạch phế quản trung tâm.

Siêu âm đàn hồi là kỹ thuật mới, quan sát tổn thương theo chiều kích mới, đó là dựa vào độ cứng của tổn thương. Chúng tôi chưa tìm thấy báo cáo nghiên cứu nào trước đây về siêu âm đàn hồi chẩn đoán tổn thương đặc ở phổi.

Kỹ thuật tạo hình xung lực bức xạ âm (Acoustic Radiation Force Impulse Imaging – ARFI) trên máy Siemen Acuson S2000 là kỹ thuật dùng chùm sóng âm tập trung tác động vào vùng quan tâm (region of interest - ROI) gây sự dời chỗ mô. Sự dời chỗ sinh ra sóng biến dạng là sóng ngang. Kỹ thuật này gồm hai phần: Một là bản đồ đàn hồi (VTI-Virtual Touch Tissue Imaging), ghi lại sự dời chỗ mô, với quy luật vật lý là mô càng cứng thì sự dời chỗ càng ít và được mã hóa thành màu đen. Hai là định lượng vận tốc sóng biến dạng (VTQ-Virtual Touch Tissue Quantification) với quy luật vật lý là mô càng cứng thì tốc độ truyền sóng càng cao (hình 8).

Mục đích

Sử dụng kỹ thuật ARFI khảo sát các tổn thương đặc phổi ngoại vi, kết hợp với siêu âm B-mode và Doppler để đánh giá khả năng của kỹ thuật ARFI trong chẩn đoán phân biệt các tổn thương này.

Phương pháp và đối tượng

Tổng số 28 bệnh nhân tại Trung tâm Y khoa Medic từ tháng 10 năm 2008 đến tháng 12 năm 2012, tuổi từ 18 đến 79, có 16 trường hợp viêm phổi thùy (57,1%), 6 trường hợp xẹp phổi (21,4%), 4 trường hợp ung thư phế quản (14,2%), 2 trường hợp lymphoma di căn phổi (7,1%).

6 trường hợp được làm siêu âm đàn hồi ARFI, bao gồm 3 trường hợp viêm phổi thùy và 3 trường hợp xẹp phổi. Mỗi trường hợp được đo ARFI (VTQ) 5 lần. Sử dụng phần mềm thống kê Medcalc để so sánh giá trị ARFI (V=m/giây) giữa hai nhóm.

Tất cả các trường hợp đã được chụp X-Quang phổi, xét nghiệm máu và siêu âm bằng đầu dò cong 3,5 MHz hoặc đầu dò thẳng 7,5 MHz trên nhiều loại máy siêu âm (Siemens, Aloka, Medison,…). Chụp cắt lớp vi tính dùng trong các trường hợp chẩn đoán không rõ ràng (10 trường hợp, 35.7%).

Kết quả

16 trường hợp viêm phổi thùy, thường ở thùy dưới của phổi (87,5%), có hình tam giác (94%), bờ đều (68,7%), đồng phản âm với mô gan (25%), có khí ảnh nội phế quản (air bronchogram) (94%), có hình ảnh cây mạch máu (9 trường hợp, 56%), phổ 3 pha kháng lực cao trên siêu âm Doppler (7/9 trường hợp, 77,8%) (hình 1, hình 2).

6 trường hợp xẹp phổi, thường có hình tam giác (100%), bờ đều (83,3%), tăng âm (100%), cây mạch máu (2/6 trường hợp), phổ Doppler 3 pha kháng lực cao (2/2 trường hợp), khí ảnh nội phế quản (50%) (hình 3, hình 8).

    

4 trường hợp ung thư phế quản, thường có hình bầu dục (75%), bờ không đều (75%), giảm âm (100%), không có khí ảnh nội phế quản, có mạch máu đơn lẻ (4 trường hợp, 100%), phổ 1 pha kháng lực thấp (3/4 trường hợp, 75%) (Hình 4, Hình 5).

    

               

Lymphoma có hình tròn hay oval, phản âm kém giống và mạch máu đơn lẻ, không có khí ảnh nội phế quản (Hình 6).

          

Vận tốc sóng biến dạng của viêm phổi thùy từ 2,06 đến 4,02 m/giây (trung bình=3,11 ± 0,99 m/giây), và của xẹp phổi từ 0,94 đến 1,93 m/giây (trung bình=1,52 ± 0,46 m/giây). Có sự khác biệt có ý nghĩa thống kê giữa hai nhóm với t = 2,896 (p = 0,034) (hình 7, hình 8).

Kết luận

Đây là một nghiên cứu sơ bộ về siêu âm đàn hồi ARFI trong chẩn đoán phân biệt tổn thương đặc phổi ở ngoại vi, kết hợp với siêu âm B-mode và Doppler. Kết quả ban đầu cho thấy vận tốc sóng biến dạng ARFI của viêm phổi thùy cao hơn (cứng hơn) vận tốc sóng biến dạng của xẹp phổi.

Trong tương lai, cần nghiên cứu với số lượng lớn để xác nhận khả năng của kỹ thuật này và ứng dụng trong thực hành lâm sàng.

Tài liệu tham khảo

1.     Roee Lazebnik S., MD Ph.D.,Tissue Strain Analytics - Virtual Touch Tissue Imaging and Quantification, Siemens ACUSON S2000 Utrasound System, Siemens Medical Solutions, USA, Inc, Mountain View, CA USA, 2008.’

2.     Color Doppler Sonographic Mapping of Pulmonary Lesions, Evidence of Dual Arterial Supply by Spectral Analysis, Christian Görg, MD, Ulf Seifart, MD, Konrad Görg, MD and Gerhard Zugmaier, MD Medizinische Universitätsklinik, Marburg, Germany.

3.     HEPATIZATION OF A LUNG LOBE AS A CAUSE OF PERSISTENT COUGH, Ali Emad MD, Shiraz University of Medical Sciences, Shiraz, Iran.

4.     Real-time lung ultrasound for the diagnosis of alveolar consolidation and interstitial syndrome in the emergency department. Volpicelli, Giovanni; Silva, Fernando; Radeos, Michael. European Journal of Emergency Medicine: April 2010 - Volume 17 - Issue 2 - pp 63-72.

 

EMERGENCY ULTRASOUND

 

 

 

 

Ultrasound is a useful, nonradiated, noninvasive, real-time, dynamic, and inexpensive diagnostic modality for immediate assessment at emergency departments. It allows findings to be directly correlated with a patient’s clinical presentations, provides efficient diagnosis, and decreases medical errors. Additionally, it can be used repeatedly if the patient’s condition changes, like an “ultrasound stethoscope” [1,2].

 

Emergency ultrasound (EUS) has developed substantially in the past 20 years. In the history and development of this field, “point-of-care ultrasound”, “bedside ultrasound”, and “focused ultrasound” are the interchangeable terms for EUS that can describe its characteristics [3]. EUS is considered integral to the clinical practice of emergency medicine [4], involving multidiscipline and goal-directed scanning. However, some authors suggested that EUS was limited and less comprehensive, compared to other ultrasound subspecialties [5].

 

In the United States, the American College of Emergency Physicians has instructed comprehensive guidelines of EUS as a standard for residency training. The guidelines comprise 11 core applications: trauma, intrauterine pregnancy, abdominal aortic aneurysm, cardiac, biliary, urinary tract, deep vein thrombosis, soft tissue, thoracic, ocular, and procedural guidance; and five scopes: resuscitative, diagnostic, procedural guidance, symptom/sign based, and therapeutic [6]. Additionally, the registered diagnostic medical sonographer certification, through the American Registry for Diagnostic Medical Sonography, is available for emergency physicians. However, controversies exist because this certification does not ensure or measure a physician’s competency [4].

In Taiwan, the “Ultrasound Subcommittee” of the Taiwan Society of Emergency Medicine (TSEM) was set up in 2008. The first committee chairman was Professor Hsiu-Po Wang. He contributed to the integration of professional work, and established a communication platform between the TSEM and the Taiwan Society of Ultrasound in Medicine (TSUM). Due to his efforts, the trabasic and advanced courses for EUS have been worked out by the TSEM since 2008. The “Emergency Subcommittee” of the TSUM and the credentialing system for the EUS instructors were established in 2009. Additionally, the academic forum “EUS” was initiated in 2009, in the annual meeting of the TSEM.

The certification program for the EUS instructors by the TSEM was established in 2012. Therefore, there are two kinds of certifications for the EUS instructors in Taiwan, through the TSEM or the TSUM. Till now, there are more than 40 EUS instructors to contribute to the EUS education in Taiwan.

In the field of academic development, previous studies focused on the application of EUS in critical care and resuscitation, mainly echocardiography [5,7e9]. Authors in Taiwan also contributed to the advances: Lien et al [10] proposed that hepatic portal venous gas was associated with poor prognosis in patients with cardiac arrest; Chang et al [11] suggested that a longer isovolumic relaxation time predicted poor survival outcomes at the postresuscitation period;Wang et al [12] concluded that in patients with plasma B-type natriuretic peptide levels within 100e500 pg/mL, cardiac ultrasound can help differentiate heart failure or not; Chou et al [13,14] proposed that the application of the

tracheal rapid ultrasound examination (TRUE) to examine endotracheal tube placement during emergency intubation and resuscitation was feasible and could be performed rapidly; and Simet al [15] showed that the positive predictive value of bilateral lung sliding in confirming proper endotracheal intubation was high, especially among patients with a cardiac arrest.

In this issue of Journal of Medical Ultrasound, Sun et al present a prospective observational study confirming the accuracy of tracheal tube placement using the TRUE protocol in the emergency departments of two medical centers [16]. The protocol used is following the previous serial studies: in case of tracheal tube intubation, only one air-emucosa interference is detected; in case of esophageal tube placement, a second airemucosa interference will appear, and the pattern then suggests a false second airway “double tract sign” [13].

Sun et al showed a good accuracy of the TRUE protocol in cardiac arrest patients by trainedining curricula including emergency physicians in twomedical centers in Taiwan [16].

This study is considered an extension of the previous single institutional study, and one part of the future multicenter study.

Sun et al also reviewed prehospital applications of EUS in many situations in this issue, including in patients with cardiac arrest, trauma, and acute dyspnea, as well as in high altitude environment or helicopters. Additionally, previous studies suggested that education of paramedics regarding ultrasound use might be feasible [17,18].

Although the accuracy of images can be improved by communication technologies [19], whether paramedics can perform EUS still depends on different national conditions.

EUS is an emerging ultrasound subspecialty that still has many issues to be explored. Presentation of the emergency department patients is diverse, and EUS can be applied in a prehospital setting, in hospitals, and during the post-resuscitation period. In this issue, some interesting articles on EUS are provided. More efforts will be needed to carry out EUS research in depth and breadth.

ARFI for ACUTE PANCREATITIS

Discussion

In this study, all 88 patients (100%) with acute pancreatitis had a diagnosis by ARFI elastography, whereas only 47 patients (53.4%) had a correct diagnosis by B-mode sonography. Computed tomographic scans were performed on 41 of the 88 patients, and only 31 of these patients (76%) had a correct diagnosis. These results demonstrate the high success rate of ARFI elastography for diagnosing acute pancreatitis and the superiority of this method to B-mode sonography and CT.

Success rates for identifying abnormalities on sonography in patients with acute pancreatitis range from 33% to 90%.³ Sonography is a useful tool for detecting gallstones, which are important in the etiology of acute pancreatitis. It is also used to exclude other potential causes of acute abdominal pain. However, because the pancreatic parenchyma is difficult to detect in obese patients and patients with flatulence, diagnosis of acute pancreatitis based on sonography can be difficult.³

Computed tomography is accepted as the primary imaging technique for diagnosis of acute pancreatitis and detection of its severity.³ The advantages of CT lie in its abilities to image retroperitoneal organs, abdominal ligaments, the mesentery, the omentum, and the pancreas. The diagnostic sensitivity of CT for acute pancreatitis ranges from 77% to 92%.^14–16 In patients with less severe acute pancreatitis, CT results may be negative.² In our study, 10 patients with CT scans that revealed a normal pancreatic size, a normal pancreatic density and heterogeneity, and no peripancreatic inflammation or fluid had a diagnosis of acute pancreatitis by ARFI imaging. This finding suggests that ARFI elastography can successfully detect pancreatic inflammation visually and quantitatively even in cases of less severe pancreatitis.

The inflammation observed in acute pancreatitis may be segmental rather than diffuse. With a frequency of 18%, the segmental form is rare,^17,18 generally involves the pancreatic head, and occurs with stones.^19–21 We found that the inflamed segments of the pancreas had color scores higher than 2 on the VTI images, and the unaffected areas had scores of 1 or 2. In 10 patients (11.3%) with segmental involvement, only the head was affected, and 5 (5.6%) had involvement of the head and a portion of the body. Among all of the patients with segmental involvement, the VTQ values were higher for inflamed tissue sites than those of noninflamed or less inflamed sites. These data show that ARFI elastography can be used to visualize the location of inflammation in the pancreas and to determine whether that inflammation is segmental.

During the arterial phase of intravenous administration of a contrast medium bolus, the normal pancreas should enhance homogeneously. Mild inflammation and interstitial edema do not interfere with the expected homogeneous enhancement of the gland. When necrosis is present, an absence of contrast enhancement, liquefaction, and changes in the density or signal intensity of the gland are observed. A study of a series of 93 patients found an overall accuracy rate of 85% for CT, with 100% sensitivity for extensive glandular necrosis.²² In this present study, the virtual and quantitative VTQ values for the necrotic areas were evaluated for the 6 patients with necrotizing pancreatitis. Computed tomography is more accurate than sonography for detection of necrotic areas in the pancreatic parenchyma. The necrotic areas in the pancreas appeared enlarged and hypoechoic on B-mode sonography, which suggests decreased stiffness, and produced low VTQ values on ARFI imaging. The VTI scores for the enlarged glands were either 1 or 2, and quantitative measurements of the necrotic areas ranged from 0.5 to 1.2 m/s. Based on these results, ARFI elastography may be helpful for diagnosis of necrotic pancreatitis.

Only 1 previous study in the literature evaluated the diagnosis of acute pancreatitis with ARFI elastography. In that study, patients with acute pancreatitis and those with resolving pancreatitis were compared with patients who had chronic pancreatitis and a control group.²⁰ The authors of that study reported average VTQ values of 2.38 m/s for the patients with acute pancreatitis and 1.28 m/s for those with a normal pancreas. We found a mean VTQ value of 2.14 ± 0.74 m/s and a range of 1.1 to 4.47 m/s for the patients with acute pancreatitis. The mean VTQ value for normal parenchyma was 1.17 ± 0.24 m/s and ranged from 0.6 to 1.63 m/s. A previous study reported VTQ values ranging from 1.48 to 2.50 m/s in acute resolving pancreatic necrosis, whereas we found that VTQ values ranged from 0.5 to 1.2 m/s in necrosis. In the previous study, the VTQ cutoff value was chosen as the upper limit of the 95% confidence interval (1.792–2.157 m/s) of the mean VTQ value of the entire study population (2.088 ± 1.155 m/s) and was rounded to 2.2 m/s. The acute and resolving pancreatitis groups were distinguished with 97.1% sensitivity and 92.9% specificity. In contrast, we found that VTQ distinguished pancreatitis from normal parenchyma with 100% sensitivity and 98% specificity when the cutoff point was defined as 1.63 m/s. The differences between the previous study and our study may be attributable to our study’s exclusion of patients with chronic pancreatitis or the combination of patients with acute and resolving pancreatitis in the previous study.

Our study had limitations. First, the quality of the images obtained with ARFI elastography depends on the abilities of the operator. Optimal images and quantitative results cannot be obtained from patients with tachypnea, tachycardia, or obesity. In obese patients, the pancreas is located deep inside the body (>8 cm), and this evaluation cannot be performed. Another limitation of the ARFI technique is limited visualization of the pancreas on B-mode sonography. Since ARFI evaluation of the pancreas starts after B-mode sonography, poor visualization of the pancreas on B-mode sonography may result in inadequate interpretation of the pancreas on VTI and VTQ. In our study, we excluded obese patients, since visualization of the pancreas on B-mode sonography was difficult. Additionally, the relationship between ARFI elastographic results and the severity of pancreatitis was not assessed in terms of morbidity and mortality. However, we believe that this study will lead to other, more exhaustive studies in the future.

In conclusion, ARFI elastography is a noninvasive, radiation-free, rapid, and reproducible imaging method that can efficiently diagnose acute pancreatitis at hospital admission. It provides reliable results that visualize the distribution of inflammation in glands, peripancreatic inflammation, and necrosis. Furthermore, the positive diagnoses yielded by elastography in patients with negative CT findings are novel results.

ARFI for NORMAL PANCREAS at MEDIC CENTER=

Of 30 normal pancreas from 30 male inviduals, age 20-40 yo,  we have mean elastic velocity of pancreas = 0.96+/-0.16 m/s (range 0.6-1.19m/s) while according to Goya et al in the text above, the mean VTQ value for normal parenchyma was 1.17 ± 0.24 m/s and ranged from 0.6 to 1.63 m/s. 

NHÂN CA VIÊM TỤY CẤP N 3 TẠI MEDIC.
Sau uống rượu đau bụng nhiều từ 3 ngày trước,  bệnh nhân được khám siêu âm, thử máu amylasemia không tăng, lipase tăng và CRP tăng. CT cho thấy viêm tụy phần đuôi, có tạo nang giả như siêu âm ARFI  tụy.

Ca viêm đầu tụy khu trú tái phát:
Tổn thương phù nề echo poor có nang hóa vùng đầu=76x88mm, ARFI=2,6-2,8m/s;  thân và đuôi bình thường. ARFI thân và đuôi v=1,9cm/s

CA VIÊM TỤY MẠN [UỐNG RƯỢU]

Mô tụy xơ hóa toàn bộ, có vôi hóa rải rác, kích thước=23-13-17mm. Ông tụy chính Wirsung giãn 7-12mm không sỏi, thành dày nhiễm cứng. 

ARFI mô tụy= 1,78-1,84m/s

MULTICOMPARTMENT PELVIC FLOOR ULTRASOUND

Abstract

Objective:

Comprehensive assessment of the pelvic floor (PF) provides information and diagnoses of coexisting abnormalities that may affect operative decisions. Our aim was to establish if pre-operative PF ultrasonography (PFUS) in patients complaining of PF dysfunction can complement clinical findings and contribute to additional management strategies.

Methods:

Females were recruited from the urogynaecology/gynaecology clinics between July and October 2009 and underwent pelvic organ prolapse quantification (POPQ) by an independent examiner. PFUS was performed using two-dimensional (2D) transperineal ultrasound (TPUS), high-frequency 2D/three-dimensional (3D) endovaginal ultrasound (EVUS) using a biplane probe with linear and transverse arrays and a 360° rotational 3D-EVUS. The clinician performing PFUS was blinded to POPQ results. POPQ and PFUS were repeated at 1 year. Two clinicians analysed the scans independently.

Results:

158 of 160 females had a POPQ and PFUS. 105 females had pelvic organ prolapse and/or incontinence and 53 asymptomatic females were controls. 26 additional ultrasound diagnoses were noted at baseline and 46 at 1 year using 2D-TPUS and EVUS. Only one female with additional diagnoses on PFUS needed surgical intervention for this condition.

Conclusion:

Multicompartment PFUS identifies additional conditions to that diagnosed on clinical assessment. However, it neither changes the initial surgical management nor the management at 1-year follow-up and therefore clinical assessment should not be substituted by PFUS.

Advances in knowledge:

PFUS can be helpful in providing additional information; however, it does not change the initial management of the patient and therefore should not replace clinical assessment.

PREHOSPITAL ULTRASOUND

Introduction

Ultrasound (US) is a useful diagnostic tool for use in hospitals. It is noninvasive and inexpensive, and causes no radiation exposure. Besides radiologists, many emergency physicians use US to assist in their decision making during critical conditions [1]. With the current improvement in technology, US machines have become more portable and are available with a better resolution. Ziegler et al [2] reported that a portable device had approximately 90% accuracy compared with high-end devices. US machines such as PRIMEDIC HandyScan, V-scan, and Sonosite are commonly used as portable devices in prehospital settings.

US has been brought to prehospital settings as a result of the recent advances in technology [3]. A prehospital setting is a unique, most likely noisy, and often limited space. Traditionally, diagnostic tools used in prehospital settings are based on history taking and physical examination.

Physical examination alone cannot be sufficient to diagnose certain conditions [4]. In addition, many studies suggested that prehospital US can change the final diagnosis and treatment [5,6]. Prehospital US has a variety of applications, such as focused assessment with sonography in trauma (FAST) [5], assessment of cardiac arrest [7], lung US (mainly in pneumothorax) [6,8], and others. Countries that have studied prehospital US extensively include Germany, France, Italy, and the United states [9]. Literature was reviewed and discussed in the following sections.

Feasibility of US in a prehospital environment

Because a prehospital space is unique and limited, a US machine should be smaller in size but should have better image quality. Some studies performed US at the scene, and others in a vehicle, such as an ambulance or a helicopter. If performed at the scene, the delivery time to hospital may be prolonged, and if performed in a helicopter or an ambulance, the transporting environment may influence the scan. There are studies of prehospital US in a fixed wing and helicopter, which showed good results. However, Melanson et al [10] reported in their study that the lack of sufficient time during helicopter transport and a proper lighting system in the helicopter can compromise the results of FAST examination. Snaith et al [11] reported that FAST and abdominal aortic aneurysm (AAA) performed in a static and ground ambulance is of good quality due to the availability of sufficient time and is comparable to that performed at the emergency department.

In Taiwan, emergency medical services mainly involve ground ambulances, and most of the ambulance beds are located at the left side; hence, left-hand-based practice may be helpful for performing the scan. Fixation of machines to the frontal areas of ground ambulances may be helpful in reducing shaking.

Educating paramedics about US

Many studies have invested in the learning curve for US, especially in FAST. They concluded that a 1-day course,including lecture and hand-on practice, can generate good accuracy and competency [12]. Heegaard et al [13] designed a FAST training course, which lasted 7 hours, for emergency nurses and paramedic flight crews; they reported 100% sensitivity and specificity in nontrauma patients, and 60% sensitivity and 93% specificity in trauma patients after 1 year of training. Kim et al [14] also reported that a 4-hour FAST training course for intermediate emergency medical technicians (EMT) resulted in 61% sensitivity and 96.3% specificity.

USEFUL

USEFUL: Ultrasound Exam for Underlying Lesions Incorporated into Physical Exam
Jon Steller, MD, Bianca Russell, MD, Shahram Lotfipour, MD, MPH, Graciela Maldonado, MD, Tim Siepel, MD, Halsey Jakle, MD, Stacy Hata, BS, Alan Chiem, MD, RDMS, John Christian Fox, MD, RDMSDisclosures
Western J Emerg Med. 2014;15(3):260-266.

ABSTRACT

Introduction: The Ultrasound Screening Exam for Underlying Lesions (USEFUL) was developed in an attempt to establish a role for bedside ultrasound in the primary and preventive care setting. It is the purpose of our pilot study to determine if students were first capable of performing all of the various scans required of our USEFUL while defining such an ultrasound-assisted physical exam that would supplement the standard hands-on physical exam in the same head-to-toe structure. We also aimed to assess the time needed for an adequate exam and analyze if times improved with repetition and previous ultrasound training.

Methods: Medical students with ranging levels of ultrasound training received a 25-minute presentation on our USEFUL followed by a 30-minute hands-on session. Following the hands-on session, the students were asked to perform a timed USEFUL on 2–3 standardized subjects. All images were documented as normal or abnormal with the understanding that an official detailed exam would be performed if an abnormality were to be found. All images were read and deemed adequate by board eligible emergency medicine ultrasound fellows.

Results: Twenty-six exams were performed by 9 students. The average time spent by all students per USEFUL was 11 minutes and 19 seconds. Students who had received the University of California, Irvine School of Medicine's integrated ultrasound curriculum performed the USEFUL significantly faster (p< 0.0025). The time it took to complete the USEFUL ranged from 6 minutes and 32 seconds to 17 minutes, and improvement was seen with each USEFUL performed. The average time to complete the USEFUL on the first standardized patient was 13 minutes and 20 seconds, while 11 minutes and 2 seconds, and 9 minutes and 20 seconds were spent performing the exam on the second and third patient, respectively.

Conclusion: Students were able to effectively complete all scans required by the USEFUL in a timely manner. Students who have been a part of the integrated ultrasound in medicine curriculum performed the USEFUL significantly faster than students who had not. Students were able to significantly improve upon the time it took them to complete the USEFUL with successive attempts. Future endpoints are aimed at assessing the feasibility and outcomes of an ultrasound-assisted physical exam in a primary care setting and the exam's effect on doctor-patient satisfaction.

Introduction

Records of Hippocratic physical examinations, influenced by the Egyptian, Cretan and Babylonian exams taught before them, included: careful history taking, inspection, palpation, and direct auscultation, and are a tradition that has continued on for thousands of years.[1] It is a great model, yet it is one that has seen few technological advances. Progress was made with the invention of the stethoscope by Laennec in 1816, and was further improved upon by Leyton, Kerr, Bowles, Rappaport, Sprague and Littmann. As newer stethoscopes improved the diagnostic sensitivity and specificity of auscultation, they were implemented into the physical examination. For Ramsay once wrote of Dr. Leyton in the British Medical Journal in 1916, "In spite of careful inquiry into the history of cases and in spite of the many accurate methods of investigation which are nowadays at our command, we cannot invariably form a perfectly definite opinion as to the cause of a patient's symptoms. Any new instrument, therefore, which can help us in our decisions should be of real use to the profession."[2] While his message encourages progress, utilization of new tools in medicine requires a detailed examination of risks and benefits. In modern medicine, we struggle to balance the cost of innovation, time constraints, management of incidental and benign exam findings, patient satisfaction, and managed health care. Our skepticism and curiosity of medical advances drive the use of the scientific method to investigate such developments before they are accepted and implemented by the community of physicians—before they can drive progress.

Over the years, various uses of bedside ultrasound have been adopted by specialties including emergency medicine, obstetrics and gynecology, and trauma. While its use in those fields has been rigorously studied in clinical settings and is the preferred first-line imaging modality for assessment of many of the organs in the abdomen and pelvis,[3] little has been reported on its role in an outpatient primary care setting and this has inspired us to consider the possible role of ultrasound as an addition to the standard physical exam. Given the recent affordability and improved image quality of bedside ultrasound units, we believe bedside ultrasound could be the new figurative stethoscope.

With this first paper, our primary endpoints were to examine the feasibility and time requirements of a medical student-performed ultrasound-assisted physical exam, termed the Ultrasound Screening Exam for Underlying Lesions (USEFUL), wherein students with varying levels of expertise would be evaluated on their ability to correctly and efficiently image individual organs from head to toe. We also sought to define our ultrasound-assisted physical exam for further medical student education and for clinicians interested in integrating ultrasound into their physical exams. Aware of the time restraints for physicians in outpatient clinics, we determined six minutes or less would be an acceptable length for a USEFUL and hoped this would be a reasonable goal. The USEFUL was developed by students and faculty interested in establishing a role for bedside ultrasound in the primary and preventive care setting with the hope that, in the future, an ultrasound-assisted physical exam that would take approximately six minutes might supplement the standard hands-on physical exam.

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US ELASTOGRAPHY for VARICOSE VEINS of LOWER EXTREMITIES

Aims and objectives

To assess a feasibility of ultrasound elastography for monitoring of conservative therapy of the varicose veins of lower extremities with a drug containing micronized purified flavonoid fraction (MPFF).

Ultrasound elastography, as a technique evaluating the elastic properties (stiffness) of tissues, was carried out after standard ultrasound examination. The elasticity of biological tissue describes its ability of reversible deformation, i.e. the property to exert mechanical resistance when the force is applied and to regain the original shape after removal of force. Elastography image is a graphical representation of the displacement of tissue layers under the influence of several cycles of compression/decompression of the investigated vein by sensor. The received echo signal is processed by the device, and the color-coded information on the displaceability of the studied tissue layers is displayed.

The dense tissue is indicated in blue, the tissue with moderate elasticity - in green and yellow-green, and softer tissue - in red.

According to our data, the unaltered vein has a soft-elastic structure of the vessel wall/perivasal tissues complex, which is uniformly encoded in green or yellow-green. The width of soft-elastic limbus around the vein is determined by the size of the vessel, as well as the presence of abnormalities. During the USEG of veins and adjacent tissues we evaluated the area of perivasal tissues on the posterior wall of the vessel at the moment of maximal decompression, which has a homogeneous elasticity, as well as the width of perivasal zone of tissue elasticity (Figures 1a, 1b). The vein is coded in red as the softest structure because of the presence of liquid component and formed elements that can move and, therefore, determine a high degree of relative elasticity of the tissue.

Conclusion

The study has shown that the changes identified using the ultrasound elastography are more pronounced in the vessels of large diameter. Intact veins of lower extremities have a homogeneous image of elastogram, suggesting about unaltered histological structure of these tissues. In the presence of varicose transformation, the heterogeneous elastography pattern reflected, probably, the disturbance of histological regularity of tissues surrounding the vessel.

The therapy with MPFF was associated with a trend to normalization of elastographic image of vessel, which relates to the reduction of the severity of aseptic inflammation and normalization of cellular structure, and, therefore, the physical properties of the studied tissue.

The obtained data confirm the feasibility of ultrasound elastography for identification of the objective markers of treatment response to MPFF in varicose disease.

STANDARDIZATION of REPORTING of ULTRASOUND FEATURES of THYROID NODULES and LYMPH NODES

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REPORTING of ULTRASOUND FEATURES of THYROID NODULES