Digital technologies are revolutionizing modern pathology, and digital pathology is expected to transform routine diagnosis as we know it. The advantages of digital pathology over traditional pathology methods are truly multitudinous, and even though the clinical adoption of digital pathology in health care settings has been somewhat slow, the increasing popularity of digital solutions has posed previously unacknowledged challenges.

The problem

One of the most significant problems arising from the growing adoption of digital technologies is that slide scanners and IT systems from different manufacturers need to be able to communicate. Slide scanners may generate image files of different formats, and it is not uncommon that these file types can be viewed and processed only by systems provided by the manufacturer of the scanner.

This lack of standardized file formats for slide scanners significantly hinders the ability to share digital pathology images and the prospects of collaboration—one of the cornerstones of digital pathology! Therefore, identifying solutions that allow flexible access to digital pathology images across multiple platforms from different vendors is paramount for an efficient pathology workflow.

The solution: DICOM standard

Digital Imaging and Communications in Medicine, or simply DICOM, was first introduced in the early 1990s as an international standard for the management and sharing of medical images and related digital metadata. In addition to the non-proprietary file format used for storage and communication of digital images (“.dcm”), the DICOM standard also includes protocols for results reporting, image compression, and image presentation.¹

The DICOM standard was developed by the American College of Radiology (ACR) and National Electrical Manufacturers Association (NEMA) and was initially used predominantly by radiologists and medical physicists for images from computed tomography and magnetic resonance imaging (MRI).²

However, the benefits of the DICOM standard were soon realized among other clinical specialists, leading to the wide implementation of DICOM in hospitals worldwide to capture, store, exchange, and transfer medical images across devices (e.g., scanners, workstations, networks, and printers) from different vendors.

DICOM services include image data storage to a picture archiving and communication system (PACS) or workstation, modality worklist (i.e., storage of image metadata including acquisition device, patient information, and procedure description), printing images through a DICOM printer, and offline media access.²

Advantages of the DICOM standard

One of the most important advantages of the DICOM standard is the fact that it solves cross-vendor incompatibility issues, as long as digital pathology devices and platforms comply with the DICOM standard. DICOM-compliant slide scanners, workstations, and printers generate and read digital pathology images of a standardized format, allowing for cross-vendor interoperability. Therefore, the wide implementation of the DICOM standard can significantly enhance the efficiency of pathology workflow.³

The DICOM standard not only provides a standardized file format for digital pathology images and related data but also offers services related to the capture and management of digital images, such as imaging procedure worklists, printing, encrypting datasets, removing patient identifying information, storing acquisition protocols, and saving image manipulations and annotations, among others.¹

In contrast to other common image formats, information in the DICOM format is grouped into datasets; thus, digital pathology images cannot be accidentally separated from digital records (e.g., patient ID, name, sex, and age) and imaging metadata. Furthermore, the DICOM modality worklist service enables the storage of details about the imaging procedure, such as the slide scanner type, procedure description, name of the referring physician, tissue type, tissue staining type/method, and detailed diagnosis. Since these details are acquired and “embedded” in the image automatically, the pathology workflow is accelerated, the productivity is increased, and the risk of erroneous data entry is minimized.^1,3

Limitations of the DICOM standard

Despite its many advantages and its tremendous potential to support the wide clinical adoption of digital pathology in routine diagnosis, the DICOM standard also has certain limitations. Although the DICOM standard can help optimize the pathology workflow by addressing technical interoperability issues, it, alone, cannot guarantee an efficient clinical workflow.

According to Gupta et al.,⁴ significant data entry issues remain to be solved in the DICOM standard. Importantly, inconsistencies in data may occur due to the many optional data entry fields it offers. Blank or incorrectly filled data entry fields may lead to inaccuracies in the image metadata. Moreover, although the standard allows for cross-vendor interoperability, images may be displayed as underexposed or overexposed when viewed on a device provided by a different manufacturer due to differences in amplitude ranges; if this occurs, the image display parameters need to be adjusted manually.⁴ To ensure identical grayscale images on different monitors and printers, the DICOM grayscale standard display function (GSDF) was developed. The function involves the integration of a lookup table to display digitally assigned pixel values; however, not all devices support this function.⁵

Another key drawback of the standard is the potential risk of malware, raising significant security concerns. If not detected by anti-virus and anti-malware software, malware embedded in DICOM-format images may compromise highly confidential clinical data and put healthcare under attack.⁶ In addition, standard Local Area Networks (LANs) and Ethernet interfaces are typically used in DICOM networks, which connect DICOM-compliant devices within healthcare organizations. Given the amount and nature of data shared through DICOM networks, organizations need to build dedicated high-performance DICOM networks, separated from other LANs used for other purposes.²

Current status and perspectives of DICOM standard adoption in digital pathology

The DICOM standard has been widely implemented for various medical imaging applications, ranging from computed tomography to MRI, ultrasonography, cardiology imaging, and dental imaging. Currently, most acquisition devices, diagnostic workstations, servers, and printers from all major manufacturers of digital medical imaging systems provide DICOM-compliant devices and services of the DICOM standard. Additionally, DICOM has been accepted and successfully adopted by numerous hospitals and diagnostic centers worldwide.²

Manufacturers producing DICOM-compliant devices are required to provide DICOM a conformance statement, which describes in detail which services of the DICOM standard each DICOM-compliant device supports.

In 2010, digital pathology applications were incorporated into the DICOM standard (Supplement 145), paving the way for standardization in digital pathology and enabling hospitals and diagnostic facilities to integrate digital pathology systems into their existing IT networks.⁷

Although the integration of the standard in digital pathology devices lags somewhat behind, the ever-growing clinical implementation of digital pathology technologies renders the adoption of the DICOM standard increasingly necessary to allow the replacement of traditional pathology methods with a fully digital pathology workflow.

References

1. Varma DR. Managing DICOM images: Tips and tricks for the radiologist. Indian J Radiol Imaging. 2012;22(1):4-13. doi:10.4103/0971-3026.95396
2. Bidgood WD, Horii SC, Prior FW, Van Syckle DE. Understanding and Using DICOM, the Data Interchange Standard for Biomedical Imaging. J Am Med Informatics Assoc. 1997;4(3):199-212. doi:10.1136/jamia.1997.0040199
3. Simon Häger. Introduction to the DICOM standard for digital pathology and its importance for workflow efficiency. Sectra. 2016:1-6.
4. Gupta M, Singh N, Shrivastava K, Mishra P. Significance of digital imaging and communication in medicine in digital imaging. Digit Med. 2015;1(2):63. doi:10.4103/2226-8561.174769
5. Digital Imaging and Communications in Medicine (DICOM) – Grayscale Standard Display Function. Vol PS 3.14.; 2011.
6. Eichelberg M, Kleber K, Kämmerer M. Cybersecurity Challenges for PACS and Medical Imaging. Acad Radiol. 2020;27(8):1126-1139. doi:10.1016/j.acra.2020.03.026
7. Singh R, Chubb L, Pantanowitz L, Parwani A. Standardization in digital pathology: Supplement 145 of the DICOM standards. J Pathol Inform. 2011;2:23. doi:10.4103/2153-3539.80719