Imaging Science Informatics PDF

23/07/2024 Imaging Science Informatics Danica P. Pardalis, RRT., MAED-EMc PTLC Lecturer CONTENTS: Fundamentals of Medical Imaging Informa...

23/07/2024 Imaging Science Informatics Danica P. Pardalis, RRT., MAED-EMc PTLC Lecturer CONTENTS: Fundamentals of Medical Imaging Informatics Medical Image Data Workflow in Radiology Basic Medical Imaging Processing and Analysis Medical Image Data Distribution and Network Practical and Clinical Imaging Information Medical Imaging Information System Evaluation and Quality Assurance 1  23/07/2024 Medical Image Data, Basic Medical Image Processing, and Analysis & Medical Imaging Informatics MEDICAL DATA Verified information regarding a person’s state of health and the medical treatment they have received. It can be recorded on paper by manual writing, or digital files using a computer. Collected and stored in clinics and hospitals, but may also be communicated to public health authorities. 2  23/07/2024 Medical Imaging Informatics In healthcare, medical informatics represents the process of collecting, analyzing, storing, and communicating information (data) that is crucial to the provision and delivery of appropriate patient care critical for health and well-being, as well as for education and research. These data are comprised of many sources such as doctors’ notes in free- form text, quantitative and qualitative measurements of various basic tests including blood evaluations, electrocardiograms, projection radiographs, more complex tests such as genetic surveys, CT, MRI, PET, and other advanced evaluations. Medical Imaging Informatics Informatics has grown substantially over the past decade to address the issues of uncertainty in handling data by converting analog input sources to digital format and ensuring an authoritative source for patient demographics and records through the implementation of digital databases and the electronic health record (EHR). 3  23/07/2024 Medical Imaging Informatics Medical imaging informatics is a sub-field of medical informatics that addresses aspects of image generation, processing, management, transfer, storage, distribution, display, perception, privacy, and security. It overlaps many other disciplines such as electrical engineering, computer and information sciences, medical physics, perceptual physiology, and psychology, and has evolved chiefly in radiology, although other specialties including pathology, cardiology, dermatology, surgery—in fact, the majority of clinical disciplines—generate digital medical images as well. Certainly, imaging informatics is an important and growing part of health and medicine. 4  23/07/2024 Medical Imaging Informatics An important part of imaging informatics includes: ▪ Ontologies (the basic communications lexicons) ▪ Standards (critical pathway to ensure interoperability of different informatics systems) ▪ Computers and networking (the information highway and communication medium), and; ▪ Picture Archiving and Communications System (PACS) infrastructure (image distribution, analysis, diagnosis, and archive). Medical Imaging Informatics The lifecycle of a radiology exam from the initial order to report distribution and action by the referring physician demonstrates the imaging informatics infrastructure and use cases necessary to achieve the goals of patient- centric care. 5  23/07/2024 Medical Imaging Informatics: Ontologies An ontology is a collection of content terms and their relationships to represent concepts in a specific branch of knowledge; relevant uses are those for medical imaging. Different usage levels include the definition of a common vocabulary, the standardization of terms and concepts, schemas for transferring and sharing information, the representation of knowledge, and the structures for constructing queries and their responses. Medical Imaging Informatics: Ontologies Benefits of ontologies include: enhancing interoperability between information systems; facilitating the transmission, reuse, and sharing of structured content; as well as integrating knowledge and data. There are many ontologies found in the field of medicine and medical imaging for the electronic exchange of clinical health information. 6  23/07/2024 Medical Imaging Informatics: Ontologies – SNOMED CT SNOMED-CT (Systematized Nomenclature of Medicine— Clinical Terms) is a standardized, multilingual vocabulary of clinical terminology that is used by physicians and other healthcare providers supported by the National Library of Medicine within the United States Department of Health and Human Services. In the United States, it is designated as the national standard for additional categories of information in the EHR and health information exchange transactions. It allows healthcare providers to use different terms that mean equivalent things when implementing software applications. Medical Imaging Informatics: Ontologies – SNOMED CT For instance, myocardial infarction (MI), heart attack, and MI are interpreted as the same issue by a cardiologist, but to software, these are all different. SNOMED-CT enables semantic interoperability and supports the exchange of normalized clinically validated health data between different providers, researchers, and others in the healthcare environment. Resources include subsets to identify the most commonly used medical codes and terms. 7 23/07/2024 8 23/07/2024 9  23/07/2024 Medical Imaging Informatics: Ontologies - ICD The International Statistical Classification of Diseases and Related Health Problems (ICD), is sponsored by the World Health Organization and is in its tenth revision (ICD-10). This is a manual that contains codes for diseases, signs and symptoms, abnormal findings, and external causes of injury or disease. Individual countries use the ICD-10 coding for reimbursement and resource allocation in their health systems and to develop their own schemas and strategies. Medical Imaging Informatics: Ontologies - ICD In the United States, variant manuals developed by the Centers for Medicare and Medicaid Services (CMS) are called ICD-10 Clinical Modification, (ICD-10-CM) with over 69,000 diagnosis codes and Procedure Coding System (ICD-10-PCS) with over 70,000 procedure codes for inpatient procedures. The ICD-10 content is used to (1) assign codes for procedures, services, conditions, and diagnoses for categorizing conditions and diseases; (2) form the foundation for healthcare decision-making and statistical analysis of populations; and (3) bill for services performed in the hospital inpatient setting. 10 23/07/2024 11  23/07/2024 Medical Imaging Informatics: Ontologies - CPT The Current Procedural Terminology (CPT) is a medical code manual published by the American Medical Association, used to describe the procedures performed on the patient during the interaction including diagnostic, laboratory, radiology, and surgical procedures. Physicians bill and are paid for services performed in a hospital, office setting, or other places of service based on these codes. Often, human coding teams or automated software tools assist in the verification and validation of codes for specific procedures for reimbursement. These codes are more complex than the ICD codes and are typically updated yearly. 12 23/07/2024 13  23/07/2024 Medical Imaging Informatics: Ontologies - RadLex In radiology, specific medical terminology and vocabularies are used to describe the anatomy, procedures, and protocols used in the day-to-day diagnosis of medical images; however, there are many procedure names and descriptions that are practice- specific. 14  23/07/2024 Medical Imaging Informatics: Ontologies - RadLex Since 2005 the Radiological Society of North America (RSNA) has gathered radiology professionals and standards organizations to generate a radiology-specific lexicon of terms called RadLex (Radiology Lexicon), and a RadLex Playbook that assigns RPID (RadLex Playbook IDentifier) tags to those terms (RSNA, 2020a). RadLex has been widely adopted in radiology and for use in registries, such as the American College of Radiology (ACR) Dose Index Registry (DIR). Medical Imaging Informatics: Ontologies - RadLex By providing standard names and codes for radiologic studies, the playbook facilitates a variety of operational and quality improvement efforts such as workflow optimization, radiation dose tracking, and image exchange. 15 23/07/2024 16 23/07/2024 17  23/07/2024 Medical Imaging Informatics: Ontologies - LOINC A more widely adopted and broader standard that covers tests and measurements in many medical domains is called LOINC (Logical Observation Identifiers Names and Codes), initiated in 1994 by the Regenstrief Institute, a distinguished medical research organization part of Indiana University. Medical Imaging Informatics: Ontologies - LOINC A harmonized effort to unify these ontologies has been established by both sponsors to use LOINC codes as the primary identifiers for radiology procedures (LOINC, 2019). A more comprehensive and widely adopted vocabulary standard will assist in making radiology procedure data more accessible to clinicians when and where they need it. 18 23/07/2024 19 23/07/2024 20  23/07/2024 Medical Imaging Informatics: Standards Organizations The acquisition, transfer, processing, diagnosis, and storage of medical imaging information is a complex process—no single system in an Information Technology (IT) environment can provide all the functionality necessary for safe, high-quality, accurate, and efficient operations. Information systems must, therefore, share data and status with each other. This requires either proprietary interfaces (expensive to implement, difficult to maintain, and tightly controlled by the vendor) or IT standards, which are consensus documents that openly define information system behavior. Medical Imaging Informatics: Standards Organizations The American National Standards Institute (ANSI) is the United States organization that coordinates standards development and accredits Standards Development Organizations (SDOs) as well as designates technical advisory groups to the International Organization for Standardization (ISO). In healthcare, two of the most important SDOs are: Health Level 7 (HL7) and the National Electrical Manufacturers Association (NEMA). 21  23/07/2024 Medical Imaging Informatics: Standards Organizations Standards, as applied to medical imaging informatics, have evolved over the years through consultation and consensus of key stakeholders, including manufacturers of medical imaging equipment, manufacturers of medical data software and systems such as the: Radiology Information System (RIS), EHR (also known as the electronic medical record—EMR), PACS, professional societies, and end-users who participate, contribute, and update the standards content to ensure interoperability and communication amongst healthcare information systems and devices. Medical Imaging Informatics: Standards Organizations Standards define communications protocols, structures, and formats for textual messages, images, instructions, payload deliveries, transactions, and a host of other information for technical, semantic, and process interoperability. ITstandards relevant to imaging include Internet standards, the HL7 standard, and the Digital Imaging and Communications in Medicine (DICOM) standard. 22  23/07/2024 Medical Imaging Informatics: Standards Organizations – Internet Standards Computer networking and the Internet are successful because of hardware, protocol, and software standards that have been developed by the Internet Engineering Task Force (IETF) of the Internet Society (https://www.internetsociety.org). The Internet is the global system of interconnected computer networks that use the Internet protocol suite transmission control protocol/Internet protocol (TCP/IP) to link devices worldwide. Medical Imaging Informatics: Standards Organizations – Internet Standards Computer networking and the Internet are successful because of hardware, protocol, and software standards that have been developed by the Internet Engineering Task Force (IETF) of the Internet Society (https://www.internetsociety.org). The Internet is the global system of interconnected computer networks that use the Internet protocol suite transmission control protocol/Internet protocol (TCP/IP) to link devices worldwide. 23  23/07/2024 Medical Imaging Informatics: Standards Organizations – Internet Standards There are many Internet standards relevant to imaging: ▪ HyperText Transfer Protocol (HTTP) is an application protocol for distributed, collaborative hypermedia information systems, and is the foundation of data communication for the World Wide Web, one of many application structures and network services foundational to the Internet. ▪ HyperText Markup Language (HTML) is the standard markup language for documents designed to be displayed in a web browser. Medical Imaging Informatics: Standards Organizations – Internet Standards There are many Internet standards relevant to imaging: ▪ Uniform Resource Locator (URL), also known as a web address, specifies the syntax and semantics for the location and access of resources via the Internet. ▪ Network Time Protocol (NTP) is used to synchronize clocks in computer systems so that messages are interpreted in the appropriate time frame. ▪ Simple Mail Transfer Protocol (SMTP) and Internet Message Access Protocol (IMAP) are the basis for email transactions on the Internet. 24  23/07/2024 Medical Imaging Informatics: Standards Organizations – Internet Standards There are many Internet standards relevant to imaging: ▪ Multipurpose Internet Message Extensions (MIME) protocol allows the extension of email messages to include non-textual content including medical images. ▪ Transport Layer Security (TLS) and its predecessor Secure Sockets Layer (SSL) define cryptographic mechanisms for securing the content of Internet transactions. Medical Imaging Informatics: Standards Organizations – Internet Standards There are many Internet standards relevant to imaging: ▪ The Syslog Protocol is used to convey event notification messages for audit trail and logging purposes. ▪ Extensible Markup Language (XML) is a free, open standard for encoding structured data and serializing it for communication between systems and is the method of choice for most new standards development for distributed systems. 25  23/07/2024 Medical Imaging Informatics: Standards Organizations – DICOM DICOM is a set of standards-based protocols for exchanging and storing medical imaging data, as actual images and text associated with images. Managed by the Medical and Imaging Technical Alliance (MITA), a division of NEMA, it is structured as a multi- part document and its Parts are numbered. Medical Imaging Informatics: Standards Organizations – DICOM DICOM is an open, public standard, and information for developing DICOM-based software applications is defined and regulated by public committees and is now, practically speaking, universal for image exchange for medical imaging modalities. DICOM is critical to the interoperability and communication of medical imaging and associated data between medical imaging systems and imaging databases. 26  23/07/2024 Medical Imaging Informatics: Standards Organizations – HL7 HL7 refers to a set of international standards for the exchange, integration, sharing, and retrieval of electronic health information that supports clinical practice and management, delivery, and evaluation of health services. HL7 International is the ANSI-accredited organization for developing HL7 standards. Its high-level goals are to develop coherent, extendible standards that permit structured, encoded healthcare information to be exchanged between computer applications and to meet real-world requirements. 27  23/07/2024 Medical Imaging Informatics: Standards Organizations – HL7 The domains that the standard covers are extensive, and interoperability is achieved through messages and documents. There are two versions of HL7 in current use. Most health systems use HL7 Version 2 (now up to V2.8.2) for their data, which is a version developed in the 1980s before the Internet became mainstream. 28  23/07/2024 Medical Imaging Informatics: Standards Organizations – HL7 HL7 is cryptic to the uninitiated, although it is required training in informatics as it is the ubiquitous standard for automated textual information exchange in healthcare IT. One should be familiar at least with the three most common message types as they pertain to the imaging chain, respective to PACS: (1) ORU—Results; (2) ORM—Orders; (3) ADT—Admission, Discharge, and Transfer. Two of the common segment types are also important: (1) OBR—Observation Request; and (2) OBX—Observation/Result. Medical Imaging Informatics: Standards Organizations – HL7 HL7, compared to DICOM, is much less formally structured (thus allowing tremendous flexibility, but also creating the need to redefine almost every implementation explicitly). As a result, a major amount of effort in healthcare is devoted to the development, documentation, and maintenance of HL7 interfaces. HL7 integration engineering represents a significant fraction of the technical work in healthcare informatics overall, and work is underway to attain a more general model of interoperability. 29  23/07/2024 Medical Imaging Informatics: Standards Organizations – HL7 Like DICOMWeb, a development in the HL7 community is a new standard called Fast Health Interoperability Resources (FHIR—pronounced “fire”) and based on modern web services and RESTful interfaces approach that uses APIs and open standard file formats such as XML or JSON (JavaScript Object Notation) to store and exchange data. FHIR can fill the needs of the previous HL7 standards (V2, V3, CDA) and provides additional benefits in the ease of interoperability, interfaces, and access to data. 30 23/07/2024 31  23/07/2024 Medical Imaging Informatics: Computers and Networking Hardware Software and Application Programming Interface Networks and Gateways Servers Cloud Computing Active Directory Internet of Things (IoT) 32  23/07/2024 Medical Imaging Informatics: Computers and Networking Hardware Computer hardware includes the physical parts or components of a computer, such as the power supply, cooling fans, case, and motherboard. The motherboard is the main component, with integrated circuitry and backplane connectors that connect all other parts of the computer, including the central processing unit (CPU), graphics processing unit (GPU), random access memory (RAM), graphics, network, and sound cards, expansion cards, and storage devices (both fixed and removable) for temporary or permanent storage. Input and output peripherals are housed externally to the main computer and include a mouse and a keyboard, a touchpad (for laptop computers), webcams, microphones, speakers, display monitors, and printers. Medical Imaging Informatics: Computers and Networking Software and Application Programming Interface Software refers to the programs, consisting of sequences of instructions, which are executed by a computer. Software is commonly categorized as application programs or systems software. An applications program, commonly referred to as an application, is a program that performs a specific function or functions for a user. Examples of applications are e-mail programs, word processing/presentation programs, web browsers, image displays, and speech recognition programs. 33  23/07/2024 Medical Imaging Informatics: Computers and Networking Networks and Gateways Computer networks permit the transfer of information between computers, allowing computers to enable services such as the electronic transmission of messages (e-mail), transfer of computer files, and use of distant computers. Networks, based on the distances they span and degree of interconnectivity, may be described as local area networks (LANs) or wide area networks (WANs). 34  23/07/2024 Medical Imaging Informatics: Computers and Networking Networks and Gateways A LAN connects computers within a department, a building such as a medical center, and perhaps neighboring buildings, whereas a WAN connects computers at large distances from each other. Most WANs today consist of multiple LANs connected by medium or long-distance communication links. The largest WAN in aggregate is the Internet itself. Medical Imaging Informatics: Computers and Networking Servers A server is a computer on a network that provides a service to other computers on the network. A computer with a large array of magnetic disks that provides data storage for other computers is called a file server. There are also print servers, application servers, database servers, e- mail servers, web servers, and cloud servers. Most servers are now established in a “virtual machine” environment, where the virtual machine (VM) is based on a computer architecture to provide the functionality and emulation of a physical computer in a centralized location. 35  23/07/2024 Medical Imaging Informatics: Computers and Networking Servers VM instances can allow multiple OSs such as Windows and Linux; to provide multiple CPUs to a specific software instance; allocate storage space; and meet unique needs as necessary in an enterprise environment. This provides flexibility, efficiency, and ability to reallocate and expand/shrink resources as necessary to meet the needs of the informatics computing infrastructure. Medical Imaging Informatics: Computers and Networking Servers A cloud server is a virtual server running in a cloud computing environment that is hosted and delivered on a cloud computing platform via the Internet and can be accessed remotely. Configuration of such a server for a PACS server-side rendering environment requires several component servers to handle tasks within the image database such as: data extraction, DICOM conversion, image rendering, storage, and load balancing. A computer on a network that makes use of a server is called a client and is typically a workstation. 36  23/07/2024 Medical Imaging Informatics: Computers and Networking Servers A computer on a network that makes use of a server is called a client and is typically a workstation. Two common terms used to describe client-server relationships are: “Thick client” describes the situation in which the client computer provides most information processing and the function of the server is mainly to store information, whereas; “thin client” describes the situation in which most information processing is provided by the server and the client mainly serves to display the information. Medical Imaging Informatics: Computers and Networking Servers An example would be the production of volume-rendered images from a set of CT images. In the thin client relationship, the volume-rendered images would be produced by the server and sent to a workstation for display, whereas in a thick client relationship, the images would be produced by software and/or a graphics processor installed on the workstation. The thin client relationship can allow the use of less capable and less expensive workstations and enable specialized software and hardware, such as a graphics processor and multiple Graphics Processor Units (GPUs), on a single server comprised of several CPUs for specific tasks and large amounts of RAM to be used by several or many workstations. 37  23/07/2024 Medical Imaging Informatics: Computers and Networking Cloud Computing The cloud computing paradigm represents the practice of using a network of remote servers and software hosted on the Internet to deliver a service. An example of a Cloud computing provider is the email service Gmail provided by Google, while an example of a Cloud storage provider is Dropbox. Medical Imaging Informatics: Computers and Networking Cloud Computing Medical imaging software vendors are also using the Cloud to provide client services and databases over the Internet for storage and archiving of imaging and associated data to a server that is maintained by a cloud provider. Clients send files to the cloud server instead of or in addition to local storage. Cloud storage can be used as a backup in the event of local failures. 38  23/07/2024 Medical Imaging Informatics: Computers and Networking Active Directory Lightweight Directory Access Protocol (LDAP) is an open, vendor- neutral, industry-standard application protocol for accessing and maintaining directory information services over an IP network. Active Directory is a directory service developed by Microsoft for the Windows domain networks and is included in most Windows Server OSs as a set of processes and services that instantiate LDAP as well as Kerberos for security. Medical Imaging Informatics: Computers and Networking Active Directory A server running Active Directory Domain Service (AD DS) authenticates and authorizes all users and computers in a Windows domain network and assigns and enforces security policies for all computers on the network. It is also used to install or update software. 39 23/07/2024 40  23/07/2024 Medical Imaging Informatics: Computers and Networking Internet of Things (IoT) The Internet of Things (IoT) encompasses everything connected to the Internet with a unique identifier (UID), and the ability to collect and share data about their environment and the way they are used over a network without requiring human interaction. 41  23/07/2024 Medical Imaging Informatics: Computers and Networking Internet of Things (IoT) IoT includes an extraordinary number of objects, from self-driving cars, to home light switches, to fitness devices, and more. In the healthcare environment, IoT has numerous applications, from remote monitoring to smart sensors to medical device integration for dialysis machines and all imaging modalities in a Radiology Department. Medical Imaging Informatics: Computers and Networking Internet of Things (IoT) While there are many benefits, there are also challenges, chiefly about data security and device management. Interoperability is a key attribute for IoT to deliver better patient care, but also a huge potential liability with remote access and cybersecurity concerns about control of devices, breaches of privacy and loss or corruption of data. The health and safety of patients are at risk when IoT devices are not regularly patched and updated, particularly for devices outside a hospital network. 42 23/07/2024 43 23/07/2024 44  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System A PACS is a collection of software, interfaces, display workstations, and databases for the storage, transfer, and display of medical images. A PACS consists of a digital archive to store images, display workstations to permit physicians to view the images, and a computer network to transfer images and related information between the imaging devices and the archive and between the archive and the display workstations. A database program tracks the locations of images and related information in the archive and software permits the selection and manipulation of images for interpretation by radiologists and consultation by referring physicians. 45  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System Image display is a key component in the imaging chain and a significant component of the PACS. An interpretation workstation for large matrix images (digital radiographs, including mammograms) is commonly equipped with two high-luminance 54-cm diagonal 3 or 5 megapixels (MP) displays, in the portrait orientation, to permit the simultaneous comparison of two images in near full spatial resolution 46  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System A “navigation” consumer-grade display (or displays) provides access to the RIS database, patient information, reading worklist, digital speech recognition/voice dictation system, EHR, and the Internet. Images are distributed throughout the enterprise and viewed on many different types of displays. 47  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System Image Distribution Computer networks permit exchanges of images and related information between the imaging devices and the PACS, between the PACS and display workstations, and between the PACS and other information systems such as the RIS and EHR. A PACS may have its own LAN or LAN segment, or it may share another LAN, such as a medical center LAN. Medical Imaging Informatics: Picture Archiving and Communication System Image Distribution The bandwidth requirements depend upon the imaging modalities and their composite workloads. For example, a LAN adequate for a nuclear medicine or ultrasound miniPACS may not be adequate to support an entire imaging department. (The former might be adequate at 100 Mbps, where the latter may require 10 Gbps.) 48  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System Image Distribution Network traffic typically varies cyclically throughout the day. Network traffic also tends to be “bursty”; there may be short periods of very high traffic, separated by periods of low traffic. Network design must consider both peak and average bandwidth requirements and the delays that are tolerable. Medical Imaging Informatics: Picture Archiving and Communication System Image Distribution Network segmentation, whereby groups of imaging, archival, and display devices that communicate frequently with each other are placed on separate segments, is commonly used to reduce network congestion. Network media providing different bandwidths may be used for various network segments. 49  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System Image Compression The massive amount of data in radiological studies poses considerable challenges regarding storage and transmission. Image compression reduces the number of bytes in an image or set of images, thereby decreasing the time required to transfer images and increasing the number of images that can be stored. Medical Imaging Informatics: Picture Archiving and Communication System Image Compression There are two categories of compression: reversible, also called bit-preserving, lossless, or recoverable compression; and irreversible, also called lossy or non-recoverable, compression. 50  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System Image Compression In reversible compression, once the data is uncompressed, the image is identical to the original. Typically, reversible compression of medical images provides compression ratios from about two to three up to five to one, depending on the complexity of the image information. Medical Imaging Informatics: Picture Archiving and Communication System Image Compression Inirreversible compression, some information is lost and so the uncompressed image will not exactly match the original image. However, irreversible compression permits much higher compression; ratios of 15-to-1 or higher are possible with very little loss of image quality. With some standard compression schemes such as the Joint Photographic Experts Group (JPEG), an image can be compressed to a 30:1 ratio with a remarkable reduction in size. To the casual observer, the images appear similar. However, with close inspection, a significant amount of image information can be lost 51 23/07/2024 52  23/07/2024 Medical Imaging Informatics: Picture Archiving and Communication System Archive and Storage An archive is a location containing records, documents, and other objects of historical importance. I n the context of a PACS, the archive is a long-term storage of medical images on disks and tapes in DICOM format. In the context of enterprise storage, the archive is generally on a Vendor-Neutral Archive (VNA) that is a repository for all kinds of data, including DICOM and non-DICOM images, non-image data (e.g., EKG traces), and other content. Archiving of data and images is typically performed in a compressed format for efficient use of storage and network resources. 53  23/07/2024 End~.RRT 2024 54