Ultrasound scans, or sonography, are safe because they use sound waves or echoes to make an image, instead of radiation.
Ultrasound scans are used to evaluate fetal development, and they can detect problems in the liver, heart, kidney, or abdomen. They may also assist in performing certain types of biopsy.
A Service-Object Pair (SOP) Class is defined by the union of an Information Object Definition (IOD) and a DICOM Service Elements (DIMSE). The SOP Class definition contains the rules and semantics which may restrict the use of the services in the DIMSE Service Group or the Attributes of the IOD.
The image produced is called a sonogram.
Fast facts on ultrasound scansHere are some key points about ultrasound scans. More detail is in the main article.
- Ultrasound scans are safe and widely used.
- They are often used to check the progress of a pregnancy.
- They are used for diagnosis or treatment.
- No special preparation is normally necessary before an ultrasound scan.
Concept
Ultrasound scans are carried out by a sonographer.
The person who performs an ultrasound scan is called a sonographer, but the images are interpreted by radiologists, cardiologists, or other specialists.
The sonographer usually holds a transducer, a hand-held device, like a wand, which is placed on the patient's skin.
Ultrasound is sound that travels through soft tissue and fluids, but it bounces back, or echoes, off denser surfaces. This is how it creates an image.
The term 'ultrasound' refers to sound with a frequency that humans cannot hear.
For diagnostic uses, the ultrasound is usually between 2 and 18 megahertz (MHz).
Higher frequencies provide better quality images but are more readily absorbed by the skin and other tissue, so they cannot penetrate as deeply as lower frequencies.
Lower frequencies penetrate deeper, but the image quality is inferior.
How does it capture an image?
Ultrasound will travel through blood in the heart chamber, for example, but if it hits a heart valve, it will echo, or bounce back.
It will travel straight through the gallbladder if there are no gallstones, but if there are stones, it will bounce back from them.
The denser the object the ultrasound hits, the more of the ultrasound bounces back.
This bouncing back, or echo, gives the ultrasound image its features. Varying shades of gray reflect different densities.
Ultrasound transducers
The transducer, or wand, is normally placed on the surface of the patient's body, but some kinds are placed internally.
These can provide clearer, more informative images.
Examples are:
- an endovaginal transducer, for use in the vagina
- an endorectal transducer, for use in the rectum
- a transesophageal transducer, passed down the patient's throat for use in the esophagus
Some very small transducers can be placed onto the end of a catheter and inserted into blood vessels to examine the walls of blood vessels.
Uses
Ultrasound images are made from reflected sound, and a diagnosis can then be made.
Ultrasound is commonly used for diagnosis, for treatment, and for guidance during procedures such as biopsies.
It can be used to examine internal organs such as the liver and kidneys, the pancreas, the thyroid gland, the testes and the ovaries, and others.
An ultrasound scan can reveal whether a lump is a tumor. This could be cancerous, or a fluid-filled cyst.
It can help diagnose problems with soft tissues, muscles, blood vessels, tendons, and joints. It is used to investigate a frozen shoulder, tennis elbow, carpal tunnel syndrome, and others.
Circulatory problems
Doppler ultrasound can assess the flow of blood in a vessel or blood pressure. It can determine the speed of the blood flow and any obstructions.
An echocardiogram (ECG) is an example of Doppler ultrasound. It can be used to create images of the cardiovascular system and to measure blood flow and cardiac tissue movement at specific points.
A Doppler ultrasound can assess the function and state of cardiac valve areas, any abnormalities in the heart, valvular regurgitation, or blood leaking from valves, and it can show how well the heart pumps out blood.
It can also be used to:
- examine the walls of blood vessels
- check for DVT or an aneurysm
- check fetal heart and heartbeat
- evaluate for plaque buildup and clots
- assess for blockages or narrowing of arteries
A carotid duplex is a form of carotid ultrasonography that may include a Doppler ultrasound. This would reveal how blood cells move through the carotid arteries.
Ultrasound in anesthesiology
Ultrasound is often used by anesthetists to guide a needle with anesthetic solutions near nerves.
Ultrasound in emergency medicine
Ultrasound is commonly used in emergency medicine to assess various conditions, including:
- traumatic injuries
- pericardial tamponade
- fluid buildup around the heart
- hemoperitoneum, or blood leakage in the abdomen
Abdominal sonography
Gastroenterologists use ultrasound to generate images of the spleen, kidneys, bile ducts, gall bladder, liver, aorta, inferior vena cava, pancreas, and other solid organs located in the abdomen.
It can evaluate patients for suspected gallstones or inflammation of the gallbladder, known as cholecystitis.
It can detect if the appendix is swollen or inflamed, which would suggest appendicitis. Blood work would confirm an infection.
Fat and gas in the bowel can sometimes block the ultrasound waves, making diagnosis more difficult.
Newborn infants
The sonographer can perform an ultrasound scan on a newborn by placing the probe on the fontanelle, the soft spot on the top of the skull.
This can check for abnormalities in the brain, hydrocephalus, and periventricular leukomalacia, a form of white-matter brain injury.
As the fontanelle grows smaller in time, the quality of the images becomes poorer.
Obstetric ultrasonography
Ultrasound devices emit a high-frequency sound from their wand and can be used to give an image of the inside of a person's body, for example, during pregnancy.
Ultrasound is part of standard prenatal care. It gathers images of the fetus or embryo in the uterus.
Obstetric ultrasonography can reveal various aspects of both fetal and maternal health. It can also help doctors assess the progress of the pregnancy.
The probe or transducer is typically placed on the mother's abdomen, but sometimes it is placed in the vagina.
A transvaginal scan can provide a clearer picture during early pregnancy, and it may be a better option if the mother has obesity.
Doppler sonography shows the fetal heartbeat. It can help the doctor detect signs of abnormalities in the heart and blood vessels.
Ultrasound and urology
In urology, ultrasound can check:
- how much urine remains in the bladder after urinating
- the health of the organs in the pelvic region, including the uterus and testicles
In young, adult males, ultrasound can distinguish different types of swelling from testicular cancer.
Pelvic sonographies can be internal or external.
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In a male, the internal sonogram may be inserted into the rectum. In a female, it might be inserted into the vagina.
This can provide information about the prostate gland, ovaries, or uterus.
Ultrasound scans of the pelvic floor can help the doctor determine the extent of, for example, a pelvic prolapse, incontinence, or obstructed defecation.
Musculoskeletal sonography
Ultrasound can be used to examine ligaments, bone surfaces, soft tissue masses, nerves, muscles, and tendons.
What to expect
An ultrasound can be done at a doctor's office, at an outpatient clinic, or in the hospital.
Most scans take between 20 and 60 minutes. It is not normally painful, and there is no noise.
In most cases, no special preparation is needed, but patients may wish to wear loose-fitting and comfortable clothing.
If the liver or gallbladder is affected, the patient may have to fast, or eat nothing, for several hours before the procedure.
For a scan during pregnancy, and especially early pregnancy, the patient should drink plenty of water and try to avoid urinating for some time before the test.
When the bladder is full, the scan produces a better image of the uterus.
The scan usually takes place in the radiology department of a hospital. A doctor or a specially-trained sonographer will carry out the test.
External ultrasound
The sonographer puts a lubricating gel onto the patient's skin and places a transducer over the lubricated skin.
The transducer is moved over the part of the body that needs to be examined. Examples include ultrasound examinations of a patient's heart or a fetus in the uterus.
The patient should not feel discomfort or pain. They will just feel the transducer over the skin.
During pregnancy, there may be slight discomfort because of the full bladder.
Internal ultrasound
If the internal reproductive organs or urinary system need to be evaluated, the transducer may be placed in the rectum for a man or in the vagina for a woman.
To evaluate some part of the digestive system, for example, the esophagus, the chest lymph nodes, or the stomach, an endoscope may be used.
A light and an ultrasound device are attached to the end of the endoscope, which inserted into the patient's body, usually through the mouth.
Before the procedure, patients are given medications to reduce any pain.
Internal ultrasound scans are less comfortable than external ones, and there is a slight risk of internal bleeding.
Safety
Most types of ultrasound are noninvasive, and they involve no ionizing radiation exposure. The procedure is believed to be very safe.
However, since the long-term risks are not established, unnecessary 'keepsake' scans during pregnancy are not encouraged. Ultrasound during pregnancy is recommended only when medically needed.
Anyone who is allergic to latex should inform their doctor so that they will not use a latex-covered probe.
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Article last updated by Yvette Brazier on Fri 23 June 2017.
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About ultrasound scans. (n.d.). Retrieved fromhttps://www.acrin.org/PATIENTS/ABOUTIMAGINGEXAMSANDAGENTS/ABOUTULTRASOUNDSCANS.aspx
Carovac, A., Smajlovic, F., & Junuzovic, D. (2011, September). Application of ultrasound in medicine. Acta Informatica Medica 193, 168–171. Retrieved from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3564184/
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Recommended related news
Abstract
Background
Ultrasound scanning uses the medical imaging format, DICOM, for electronically storing the images and data associated with a particular scan. Large health care facilities typically use a picture archiving and communication system (PACS) for storing and retrieving such images. However, these systems are usually not suitable for managing large collections of anonymized ultrasound images gathered during a clinical screening trial.
Results
We have developed a system enabling the accurate archiving and management of ultrasound images gathered during a clinical screening trial. It is based upon a Windows application utilizing an open-source DICOM image viewer and a relational database. The system automates the bulk import of DICOM files from removable media by cross-validating the patient information against an external database, anonymizing the data as well as the image, and then storing the contents of the file as a field in a database record. These image records may then be retrieved from the database and presented in a tree-view control so that the user can select particular images for display in a DICOM viewer or export them to external media.
Conclusion
This system provides error-free automation of ultrasound image archiving and management, suitable for use in a clinical trial. An open-source project has been established to promote continued development of the system.
Background
Medical sonography (ultrasonography) uses ultrasound to provide real-time images of soft tissues, internal organs and the fetus in utero. Because medical sonography is non-invasive and generally considered to have no harmful side effects, it has seen increasing use for a variety of diagnostic purposes in recent years. One of the most common applications of ultrasound imaging is in routine obstetric care, assessing the stage and status of pregnancy and the health and development of the fetus. Other applications include the imaging of most of the internal organs, muscles, ligaments and tendons.
DICOM 3.0 (Digital Imaging and Communications in Medicine) is a standard describing the handling, transfer and storage of medical imaging data, including ultrasound scans [1]. A DICOM data object (or data set) combines a medical image in one of several standards (either still, or video) with patient information and other scan data. The linked storage of these data is an important feature of the standard, ensuring that the descriptive patient data are always associated with the correct medical image. Most modern health care facilities store these DICOM objects in a picture archiving and communication system (PACS), allowing ultrasound scan records to be managed in the same way as other types of medical images.
A considerable amount of work is currently being undertaken to evaluate the use of ultrasound in various new diagnostic procedures. The clinical trial of a new ultrasound procedure generates significant quantities of scan data that typically require cross-comparison and peer assessment. However, the nature of clinical trials often precludes the storage of data alongside patient records in an existing PACS, and the purchase of a PACS for the limited use of a trial is usually not cost effective. As a result the ultrasound scans generated by clinical trials are not always stored in a way that facilitates their management and future retrieval, and our own experience of this issue was the incentive for this project; we had attempted to manage large numbers of ultrasound images using software supplied with the ultrasound machine, only to discover that it became unmanageable when the number of images exceeded a certain threshold.
In order to satisfy the need for the management of ultrasound images without incurring the effort and expense of setting-up a commercial PACS, we have developed OSPACS. This system is based on a simple Windows application utilizing an open-source DICOM image viewer and a relational database. OSPACS is currently being used to manage the UKCTOCS (United Kingdom Collaborative Trial for Ovarian Cancer Screening) [2] ultrasound archive, providing error-free automation of ultrasound image archiving and management. An open-source project has been established in order to promote the continued development of OSPACS for UKCTOCS as well as other clinical trials.
Implementation
OSPACS is implemented using traditional client-server architecture, such that the client is comprised of a Windows Forms application (osImageManagerApp.exe), which accesses a server hosting the image database.
Software Development and Design
Development of OSPACS followed an Agile approach [3] inspired by Extreme Programming (XP) [4], utilizing practices such as Real Customer Involvement, Incremental Deployment, Incremental Design and Test-First Programming. This allowed the system to evolve in an incremental way through a series of iterations that were driven by the need to frequently deliver valuable software that satisfied the end-user (customer).
The Incremental Design practice requires design to be performed everyday instead of being confined to a particular phase during the project (as is the case in a Waterfall process) or during the iteration (as is the case in Rational Unified Process). In practical terms this means following the Test-First Programming practice so that the design evolves in a bottom-up fashion. However, Agile Modeling techniques were employed during the creation of the initial architecture and before important design decisions were taken, so the design of OSPACS was actually produced by a combination of bottom-up and top-down approaches.
Image Database
We have implemented the image database using the Microsoft SQLServer database management system (DBMS) [5]. Because this is a commercial product, the OSPACS setup program includes the option of installing the Express Edition of SQLServer, which is available free of charge from the Microsoft website [5]. SQLServer Express is functionally identical to the full commercial product in respect of OSPACS requirements, but the database size is limited to 4GB. While this constraint will significantly limit the number of ultrasound records that can be stored, the use of SQLServer Express will allow the system to be evaluated adequately.
During its design we attempted to follow the maxim of developing 'the simplest thing that could possibly work' [6]. Consequently there is just one table with eleven fields, the most important of which is the DicomFile field (see Table Table1).1). This field is an Image data type (a large binary object, or BLOB) and contains the entire contents of the DICOM object as binary data. However, as the application software only accesses the database through a set of stored procedures, it should be possible to extend this schema relatively easily.
Table 1
Column Name | Condensed Type | Nullable | |
PK | ImageID | uniqueidentifier | No |
CaptureDate | datetime | Yes | |
StoredDate | datetime | Yes | |
StoredBy | varchar(50) | Yes | |
DiskRef | varchar(50) | Yes | |
VolunteerRef | int | Yes | |
DicomRef | varchar(64) | Yes | |
DicomFile | image | Yes | |
DicomFileSize | int | Yes | |
MaskFile | varchar(255) | Yes | |
Flags | varbinary(10) | Yes |
PK indicates the Primary Key.
ezDICOM Component
The ezDICOM component is free, open source software that can be used to view a wide range of medical images including the DICOM standard and proprietary formats [7]. It has a good reputation for being mature, stable software and has been successfully used in a number of other Medical Imaging applications. OSPACS uses the ezDICOM ActiveX control under the BSD open source license.
Software Development Tools and Libraries
The OSPACS software was developed in C# using Visual Studio 2005 tools (Microsoft) and it includes a collection of automated unit tests which cover more than 95% of the code base. The user interface layer is implemented as a Windows Forms application and uses the .NET 2.0 Framework Class Library (FCL) [5] to provide the main window, dialog boxes, associated controls, etc. Non-functional requirements, such as logging and error handling, were implemented using the third-party library MxToolbox [8]. Automated functional tests were developed using the Framework for Integrated Test (FIT) library [9].
Results and Discussion
Installation
Installation of the client part of OSPACS is achieved by running the installation program (setup.exe) downloaded from the OSPACS open-source site [10]. This installation program can also install Microsoft SQLServer Express and the Microsoft .NET 2.0 Framework Library, if required. Once the basic installation has been performed the system's on-line help explains the steps required to set-up the databases.
The standard installation process will install an application called osImageManager and create both an image database and a test patient database on the local computer. The FIT automated functional tests can then be run from the application's 'Database Admin' dialog box in order to validate the system within the context of the client PC. For the system to be used in a production context it is necessary only to change the configuration of the database sources to the required servers, and then re-run the scripts from the application's Database Admin dialog box in order to create any production image database that might be required. In this way the installation of OSPACS is made simple, repeatable and reliable.
Image import
Ultrasound images in the DICOM image format can be imported as files from removable media, and information from the DICOM image header cross-checked against an external database. The current implementation of OSPACS is specific to UKCTOCS, and patient details from the DICOM header are compared to specific data fields in the patient information tables of the main UKCTOCS database. Where information in the DICOM header does not agree with a UKCTOCS database entry, the image is flagged and options to correct data in the DICOM header are provided. Following a successful validation of data in the DICOM header, the relevant information is extracted and used to populate fields in a new image database record.
Patient anonymity is protected by removing all patient-identifying information from the DICOM header data, and also by masking parts of the image data itself before populating the database record. The region of the image containing the patient identifier does not vary in scans from similar hardware, so a defined region of the image is simply over-written with white pixels.
Viewing images
Once DICOM objects have been imported into the image database they can be readily retrieved by running a standard query using values entered into a dialog box opened from osImageManager's View menu. When the dialog box is closed the records in the database matching the query value are displayed in a standard Windows treeview control, arranged in a heirarchy of scanning centre, patient ID, scan date and images (see Figure Figure1).1). Selection of an image item in the treeview displays the corresponding image in a viewing window (see Figure Figure1).1). Images can be retrieved either by reference number of the trial volunteer, or the reference number of the removable media entered during the import process.
The osImageManager application. Screenshot of the osImageManager application, showing the treeview control and DICOM viewing window.
Image export
Selected images in the treewiew can easily be saved to removable media in their original file format. While this process does not create a DICOMDIR file (defined by the DICOM standard, a directory that indexes and describes all of the DICOM files that are stored on the media) and hence is not fully compliant with the DICOM standard, these files can be opened and viewed by any DICOM viewing application.
Conclusion
OSPACS has been successfully implemented within the Gynaecological Cancer Research Centre, where it is being used to manage ultrasound images collected as part of the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS). During the course of the trial it is expected that UKCTOCS will accumulate approximately 1,500,000 ultrasound images, from 300,000 examinations, collected by 13 regional centres throughout the UK. OSPACS is currently being used to automate the import of scans from the regional centres, helping to resolve patient identifiers with the central UKCTOCS database, and to export groups of images to removable media for external review. There are currently ~200,000 ultrasound images stored in the UKCTOCS ultrasound record archive (UKCTOCS URA), which translates to ~150 Gb of disk space. In summary, OSPACS has been used to create a usable ultrasound record archive, ensuring the integrity and helping to realise the research potential of a valuable and irreplaceable resource.
Future development of the OSPACS project will include the generation of a valid DICOMDIR file during image export to removable media, enabling better integration of OSPACS with other DICOM and PACS applications. Also, support for other database management systems besides Microsoft SQLServer, such as the widely used open source (free) platforms MySQL and PostgreSQL, will be implemented. Finally, the implementation of lossless compression of the DICOM images in order to reduce the overall size of the database and increase the speed of database transactions is planned. The creation of an open source project will facilitate this continued development, and provide the opportunity for others to modify and extend the functionality of OSPACS.
Availability and requirements
• Project name: OSPACS
• Project home page: http://www.ospacs.org/
• Operating system(s): Windows XP
• Programming language: C#
• Other requirements: Microsoft SQLServer (or SQLServer Express)
• License: Cranfield Open-Source License
• Any restrictions to use by non-academics: License required
List of abbreviations
PACS: Picture Archiving and Communication System; DICOM: Digital Imaging and Communications in Medicine; UKCTOCS: The United Kingdom Collaborative Trial of Ovarian Cancer Screening.
Competing interests
The authors declare that they have no competing interests.
Authors' contributions
WS designed, wrote and implemented all source code and helped in the preparation of the manuscript, AR specified system requirements, and tested each release of the system on the UKCTOCS Ultrasound Record Archive, IJ provided infrastructure and funding support, UM contributed to the design of the project, CB supervised the work of WS towards an MSc in Bioinformatics at Cranfield University, CJ conceived and coordinated the project, and was responsible for preparation of the manuscript. All authors read and approved the final manuscript.
Acknowledgements
The authors would like to thank the UCLH Charities and Royal Free and University College Medical School Clinical Research and Development Committee, for funding awarded to CJ for payment of a Bursary to WS. This work was partly undertaken at UCLH/UCL who received a proportion of funding from the Department of Health's NIHR Biomedical Research Centres funding scheme. CJ was funded by Mermaid/Eve Appeal.
References
- DICOM http://medical.nema.org/
- UKCTOCS http://www.ukctocs.org.uk/
- Agile Manifesto http://www.agilemanifesto.org/
- Beck K, Andres C. Extreme Programming Explained: Embrace Change. Boston , Addison-Wesley; 2005. [Google Scholar]
- Microsoft http://www.microsoft.com/downloads/
- Venners B. The Simplest Thing that Could Possibly Work. A Conversation with Ward Cunningham.http://www.artima.com/intv/simplest.html
- ezDICOM http://sourceforge.net/projects/ezdicom
- MxToolbox http://www.winformstoolbox.org/
- Fit: Framework for Integrated Test http://fit.c2.com
- OSPACS http://www.ospacs.org/