Chapter 1
Introduction
After World War II, a few enthusiasts recognized the possibility of utilizing ultrasonic energy as a source for medical diagnosis. Years later their efforts were received as innovative concepts resulting in images and the production of instruments for measurement (Goldberg, Gramiak, & Freimanis,1993). Although scientists made earlier attempts to further advance imaging of the body, the ultrasound was not developed until the 1950’s, and its introduction and progression was gradual. In recent years, the quality of ultrasound imaging has improved significantly and has almost become indispensable (Fenster & Downey, 1996).
Ultrasonography, a complimentary, non-invasive exploratory tool, is valuable in detecting fluid and abnormal pathology of organs. However, the standard ultrasound machine can be cumbersome and expensive for traditional medical clinics. In addition, immediate access to ultrasound facilities is not always possible. Such factors led to the development of smaller, less expensive devices to assess fluid and pathological abnormalities (Tse, Luk, & Lam, 2014).
Commercial handheld ultrasound devices were introduced in the late 1990’s. The portable devices extended ultrasonography beyond radiology, cardiology, and obstetric use. The price of the ultrasound decreased from approximately $150,000 to $30,000 making the device more affordable to various practitioners. Along with the the low cost, the device is simple to operate, more manageable, and rechargeable. These features are ideal in low resource settings (Harris & Marks, 2009).
There have been a number of studies conducted regarding the clinical use of the handheld ultrasound device versus the conventional ultrasound. Some studies explored the value and use in the clinical setting, while others investigated time-saving capability, the ability to supplement computed tomography, and the quality of imaging between devices. Although the use of pocket ultrasound is on the rise, there are concerns regarding its miniaturization. Researchers question if the miniaturization results in a decline in the quality of imaging, leading to inaccuracy in diagnosing. Others question if the inexperience of an individual utilizing the mini device impacts interpretation leading to an increase in clinical examination time, thus reducing appropriate utility (Stock et al., 2015). The intent of this paper is to review the historical development of the ultrasound machine and ascertain the impact of miniaturization. The paper will also address imaging quality and clinical diagnosis among the handheld and conventional ultrasound, and the applicability and level of accuracy.
Chapter 2
Review of literature
Historical development
American radiologists played a significant role in the development of the ultrasound in the United States (US). Three of the earliest pioneers in the US were John Wild, a surgeon, Douglas Howry, a radiologist, and George Ludwig, an internist (Goldberg, Gramiak, & Freimanis,1993). Ludwig focused on developing experiments to identify foreign bodies in animal tissues by using reflective pulse echo which was similar to radar and sonar. Much of Ludwig’s work was considered classified by the Navy and was not published in medical journals. The majority of his work was not released to the public until October 1949 (Woo, 2008). The most influential of this group regarding the advancement of radiology was Douglas Howry. In the 1940’s, Howry left Denver Veterans Administration Hospital to dedicate his time to ultrasound research. Along with William Bliss and George Posakony, Howry and the engineers worked feverishly in his basement to capture anatomic images of soft tissue using ultrasound. By 1949, Howry and his colleagues were using radio and Air Force radar components to construct an ultrasonic scanner for two dimensional (2D) images. Howry is noted as the first to record a cross sectional image using ultrasound. This was a great first step although the completeness of the image was not the best. As time went on, other instruments were created to correct the limitation of the simple scanning motion (Goldberg, Gramiak, & Freimanis,1993).
Joseph Homes, a nephrologist at Denver Veterans Administration Hospital became Howry’s biggest ally by gaining institutional support for Howry’s project in 1951. The result of his support created funding and space for the project. During the same year, Howry and the engineers created a two dimensional ultrasound scanner. The scanner was developed by using a cattle-watering container and an ultrasonic transducer attached on a wooden rail. By immersing the transducer in the tank with the study object moving horizontally sensitivity was improved. This method could also tolerate a larger transducer and could be held away from the patient allowing enhanced focus of the beam. As a result, the images obtained in the water bath approach were better than the previously described scanner (Goldberg, Gramiak, & Freimanis,1993).
By 1954, an updated version emerged with a transducer mounted on a ring gear from a B-29-gun turret that rotated. The device was mounted to the rim of a large metal cup which functioned as an immersion reservoir. The method allowed full horizontal rotation of the tanks periphery. An additional motor created a sectoring motion while the transducer moved around the tank scanning the immersed subject. In the late 1950’s, due to the inability to immerse ill patients for extended periods, a scanner was developed with a transducer carriage that was strapped to the patient’s body and rotated. Due to the limitation of water bath systems, engineers William Wright and Edward Meyer industrialized a scanner with direct contact. A transducer was mounted with a scanning device that could be manipulated by the operator (Goldberg, Gramiak, & Freimanis, 1993).
In 1955, a Cambridge medical graduate by the name of Julian Wild, established the foundation for tissue diagnosis with the publication of the amplitude mode (A-mode). A-mode was the investigation of surgical specimens from intestinal and breast malignancies. Wild also spurned the development of the brightness mode (B-mode) instrument and created descriptions of endoscopic (transrectal and transvaginal) A-mode ultrasonic transducers (Kane, Grassi, Sturrock, & Balit, 2004).
Ian Donald was another contributor to ultrasonography. While serving in the Royal Air Force in World War II he gained experience in radar and sonar techniques. Donald along with a few of his colleagues, created a manual for a two dimensional scanner. By 1960, they developed an automatic scanner and made the first diagnosis of placenta previa using an ultrasound. In 1962, the group developed a technique to measure the diameter of the fetal head. In 1963 through utilization of a full bladder, Donald and his colleagues learned to detect early pregnancy at 6-7 weeks’ gestation (Kane, Grassi, Sturrock, & Balit, 2004).
Nearly a decade later, in 1975, the first portable ultrasound machine was available in the commercial market. The battery-powered, handheld ultrasound was not developed until the mid-1990’s (Tse, Luk, & Lam, 2014). The advancement of the handheld ultrasound stems from the intent to provide rapid point of care diagnostics through unrestrained portability. Use of the handheld ultrasound was also for subjective recognition of easy to view disease targets that do not require exact measurement (Kimura, Gilcrease, Showalter, Phan, & Wolfson, 2012). Identification, location, and viability of pregnancy with bleeding or pain and validating the presence or nonexistence of a mass, and the presence of pelvic fluid or blood in the abdomen are a few examples. Therefore, the availability of pocket ultrasound devices is vital to clinical decisions and useful in the emergency and delivery room setting to assess patients quickly. The device plays a pivotal role in the community and developing countries (Sayasneh et al., 2014). Handheld ultrasound machines continue to decrease in size and cost and serve a significant role during physical examinations. The use of the handheld ultrasound gives physicians real-time information and the ability to answer questions about the patient they are examining.
Impact of miniaturization
Ultrasound imaging can be applied to clinical applications such as fetal monitoring, procedure guidance, vascular imaging and general imaging for diagnosis. However, the backbone of patient evaluation continues to be patient history and physical examination (Panoulas et al., 2012). Handheld ultrasound devices are intended to be used as an aid to the physical examination. Due to the size and transportability, the handheld device has proven to be useful when more expensive systems are unavailable. Based on convenience and cost, the device has been utilized in a number of clinical settings where previously deemed impractical. Rapid growth of the portable system has been seen in markets such as emergency medicine and intensive care. Other areas of growth have been in rural, remote areas where physicians have limited access to departments with ultrasounds. The use of the handheld device in these locations allow physicians to assess their patients and determine if urgent medical treatment is needed that may require ground or air travel. Emergency room and intensive care physicians use the devices to save time and improve the management of patients versus transporting them between numerous locations. Similarly, obstetrical physicians and staff can easily identify a baby’s heart beat and fetal position through the use of handheld ultrasound at the point of care (Cashin-Gabutt, 2013).
A study by Bruns, Menegatti, Martins & Araujo, (2015) performed a cross sectional and prospective study of 86 pregnant women who were in their first trimester. These women were treated at an emergency obstetrics ultrasound service center. The study was conducted using a handheld device and followed by a conventional high resolution ultrasound machine. The test results performed by both machines were documented on one form. Any variance in the diagnosis was recorded. The variables investigated during examination were gestational sac, embryo, embryonic heartbeat, and uterine or ectopic pregnancy. No contradictory results were detected when the handheld device was compared to the traditional ultrasound. In regards to visualization of the gestational sac, both yielded visualization of the gestational sac in 61 patients. There was a 95 percent confidence interval indicating good agreement. Visualization of the embryo and intrauterine gestation using both devices were 87 percent. The best agreement in the study was the determination of the fetal heartbeat which was 95 percent between the devices. The conventional ultrasound had a low correlation for diagnosing ectopic pregnancies. (Bruns, Menegatti, Martins & Araujo, 2015).
A study performed by Dijos et al., (2011) with 256 patients hospitalized in a cardiology center utilized a hand held ultrasound machine to screen for abdominal aortic aneurysm (AAA). For the purpose of this study the V scan was used. This device revealed outstanding feasibility and only 2.5 percent of the screenings were unable to measure aortic diameter. The study took a look at the use of the conventional ultrasound for screening in comparison to the V scan hand held device. The study revealed a 1.2 percent screening failure. The handheld device was used at the bedside which was convenient for patients and time saving in comparison to the conventional ultrasound. Other studies have been done which show similar results. The study encouraged continued development and use of the hand held device along with sufficient training to increase reliability during patient clinical examinations. Ultimately, images captured by the handheld ultrasound device offer enough information to make informed decisions during routine assessments and some emergent situations (Dijos et al, 2011).
Applicability and level accuracy
Minimal scientific evidence exists beyond the echocardiography subspecialty to assess diagnostic performance of handheld ultrasound devices. However, there is a growing international market for manufacturers of handheld ultrasound devices. Due to the low cost, ease of use, and battery recharge capability, the devices are strongly recommended for low resource settings such as developing nations. Although ultrasound technology is not a viable option to impact treatment of infectious diseases, like malaria and the human immunodeficiency virus, it can be a useful tool in addressing maternal and neonatal mortality. For extremely impoverished nations, the ability to collect data on prenatal care, frequency of visits and monitoring maternal health is essential to reducing maternal mortality and morbidity rates. Postpartum and neonates can potentially be isolated from care, their community, and eccentric cultural practices create barriers at garnering information for birth and neonatal deaths. Countries with minimal participation in medical surveys experience the highest maternal and infant mortality rates (Harris & Marks, 2009).
Conventional ultrasound is considered too expensive to attain in low resource settings. There are also logistical challenges that render their acquisition difficult. Strong consideration has been given to the type of biotechnology needed in developing countries. The United Nations Educational Scientific, and Cultural Organization developed a 6-point framework to evaluate the value of biotechnology in developing countries. The six points are effect, suitability, significance to needs, practicality, creation of new knowledge, and social and environmental benefits of biotechnology to improve health. Developing countries benefit from the handheld ultrasound for diagnoses such as intrauterine growth restriction, multiple gestations, labors that are obstructed and congenital anomalies. The devices are also useful in reducing unsafe abortions and leads to increased quality of life regarding the latter mentioned birthing issues (Harris & Marks, 2009).
Outside of obstetrical use, handheld ultrasounds have been used for evaluation of abdominal or pelvic pain, locating and diagnosing masses, and superficial and musculoskeletal disorders. The use of the handheld ultrasound, particularly related to obstetrical patient complications is useful in considering the plan of care in low resource settings. Diagnosis at the point of care may mean referring a patient to a regional obstetric center for proper care. Even if a transfer is not possible, the supporting evidence from the handheld ultrasound has been life saving to skilled local birth attendants (Harris & Marks, 2009). Although the handheld ultrasound boasts numerous benefits, some practitioners have concerns with the increased miniaturization compromising image quality consequently lessening diagnostic accuracy based on perception and interpretation of information. Likewise, inexperience and lack of commitment to the quality impacts imaging. These factors lead to increase clinical time and reduces appropriate utility. Therefore, any advantages such as quicker transfer, easier positioning at the bedside and quicker boot time must be counter balanced by the limitations (Stock, et al., 2015).
For instance, a prospective pilot study consisting of 28 inpatients seen in nephrology, gastroenterology and toxicology for 2 weeks was conducted at the Technical University of Munich. The patients were examined with a Acuson P10 pocket ultrasound B-mode and then at the bedside with a high end instrument called Sonoline Antares. The examiners for the study each had experience utilizing ultrasound. There was one month of training on the pocket ultrasound before the study. Examiners were not primed regarding the patient’s pathology. Both examinations were carried out on the ward at the bedside. The focus of the study was to compare both devices and not necessarily detect pathologies. The study found that examination times overall were shorter with the pocket ultrasound based on shorter boot times and set up. However, the scan time with the high end ultrasound was shorter. The portable device detected 73 percent of the pathologies. Diagnostic evaluation of focal liver lesions was not a strength of the portable ultrasound which was expected. The researchers posited that this type of scan should not be completed with the miniature device. Gallstone detection was also excluded due to unreliability of imaging. The researchers felt the cost advantage was not enough to compensate for the unreliability for diagnostic accuracy. Much of this stemmed from limited quality of the b mode images. The researchers of the study believe before any portable ultrasound device is adopted it must be vigorously tested for clinical application (Stock et al., 2015).
Research Methods
The review of ultrasonography was an expansive topic to research while composing the final paper. The research was retrieved from databases which included EBSCOhost, Proquest and PubMed. The majority of the research publications were less than 10 years old. However, a few publications were between 12-23 years old, which captured the historical development and evolvement of the ultrasound machine. Key terms used when searching the databases included (a) ultrasound, (b) ultrasonography, (c) pocket ultrasound, (d) history of ultrasound, (e) handheld ultrasound, (f) ultrasound historical development, (g) ultrasound miniaturization, (h)ultrasound image quality, and (i) ultrasound applicability. The writer determined that the scope and breadth of ultrasonography was greater than the initial focus of comparing the traditional ultrasound to the compact ultrasound based on the expansive search.
Discussion
Healthcare systems aim to deliver high quality care at a low cost. Acquiring the handheld ultrasound device supports this concept. The handheld device is less expensive, convenient, and does not use radiation unlike their counterpart computed tomography and x-rays. The ultrasound no longer caters to the emergency and intensive care areas, but has expanded to be used by other specialties. A systematic review of the literature shows that handheld ultrasound devices can be used in various locations and considered indispensable. This is particularly true for obstetric care in low resource settings. The device is an ideal imaging tool; it is complimentary to the physical assessment, non-invasive, requires minimal maintenance, and utilizes a simple sound gel, usually available at local distributors (Becker et al., 2016).
Based on multiple studies, the ultrasound has been categorized as a vital tool to improving patient care (Becker et al., 2016). However, there is limited published literature on the usefulness of the handheld ultrasound as a public health response to infant and maternal mortality in developing, low-resource nations. Despite this fact, there is still an argument in favor of investigating ultrasound technology in these areas. (Campbell, 2013). The handheld ultrasound does not replace advanced, diagnostic imaging completed and interpreted by skilled technicians and radiologists. The device alone does not diagnose a condition which should be left to the discretion of a physician. With the appropriate instruction and experience, the handheld ultrasound device can guide decision making and the need for additional imaging.
Although conventional methods of examination have proven efficient and effective, new innovations with the handheld ultrasound is enhancing the way we evaluate and treat patients (Brown & Taunton, 2011).
Conclusions
The author has discussed the diverse applicability, time saving measures, and effectiveness of the handheld ultrasound in multiple settings. Considering the various sizes of the ultrasound technology, the decreasing cost, diagnostic accuracy and expanding availability, the use of the handheld ultrasound by experienced physicians shows promise and should be considered a compliment to routine examinations. The brief overview provided does not justify the range of benefits ultrasonography offers in improving the overall health of people. However, the advances seen in ultrasonography described in this paper were derived from bright engineers and doctors who persevered, advocated, and shared their developments broadly for the benefit of patients. This innovative approach improves the quality of care. Without their perseverance the world of healthcare would not experience the advancements seen in obstetrics to reduce infant mortality or cardiology to detect AAA’s. The handheld ultrasound has the potential to compliment clinical examinations, improve diagnostic screening, and reduce the risk of additional formal imaging. There remain major gaps in evidentiary support of the handheld ultrasound device, which includes the amount of training needed, the accuracy of imaging and applicability.
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