In 1979 Heinz Lemke, a computer sciences Professor of the Technical University of Berlin, and his colleagues published a report that would upend 83 years of medical imaging: A network of medical workstations for integrated work and picture communication for clinical medicine. Known as the Picture Archiving and Communication System, PACS would both revolutionize medical imaging and markedly disrupt the radiologist’s workflow.

The environment was ripe for new thinking. Data generated by the first CT scanners was growing rapidly while digital storage costs were dropping. Computational power, digital archiving, storage capacity, and broadband capability were doubling every 9 to 18 months. Arising in this new digital terrain, PACS, founded on a common protocol, would eventually be adopted throughout the industry.

With the first major installation at the University of Kansas in Kansas City in 1982, PACS became a clinical reality. It was slowly adopted through the ‘80s and ‘90s with an estimated 8% of radiology units converting by 2000. Then, in a burst of procurement, 75% of radiology units converted to PACS by 2008, drawing to a close a transformation that had lasted roughly 30 years.

The advantages of PACS over previous film technology were dramatic

PACS digitally managed x-ray plain film, computed tomography, and magnetic resonance imaging, and empowered radiologists with new diagnostic capabilities.

Image contrast settings could be quickly toggled to settings ideal for visualizing bone, lungs, brain, or soft tissue. A digital magnifying glass allowed the radiologist to zoom in on an area of interest.

It provided an efficient method for evaluating the hundreds of images being produced by CT and MRI scanners. Instead of viewing images on large view boxes, the radiologist could quickly scroll through digitally stacked images by “rolling a mouse ball.”

A critical weakness of film technology – the difficulty in finding a patient’s previous images – was largely overcome. Comparing a suspicious area to an older study stored in the PACS decreased the need for additional testing, such as a biopsy.

Since loss of images could also occur in PACS, HIPAA required “facilities have a means of recovering images in the event of an error or disaster.”

The most visible change from the patient’s perspective was the elimination of the need to physically transport large film jackets to the physician’s office. PACS broke “down the physical and time barriers associated with traditional film-based image retrieval, distribution, and display.”

PACS also gave birth to teleradiology, the remote access and interpretation of medical images. Furthermore, PACS could be integrated with other digital systems such as the electronic medical record and hospital information system.

PACS disrupted the radiologist workflow

While PACS was becoming an unqualified technological success, a secondary impact was becoming apparent: the significant disruption of the radiologist’s workflow. As Lemke observed:

“These are technologies that change the pattern of people’s behavior, their workflow, quite dramatically.”

PACS changed “the way diagnoses are made and communicated and how radiologists interact with one another and with referring physicians.” A provider with a connected computer could now visualize images and reports while on the ward, in the office, or at home. Person-to-person discussions between the provider and radiologist decreased significantly. Concern was raised that radiologists were becoming “disembodied functionaries, more akin to servicing technicians than professional colleagues.”

The disconnection between the radiologists and the treating team was further aggravated by an increase in the radiologist’s workload. Evaluating the increasing number of images generated by constantly improving scanners was tedious and the evaluations had to be performed quickly as “insurance companies and Medicare … slashed reimbursement for each interpretation.”

With the growing demands on radiologists, a provider’s visit to the radiology reading room could be viewed as an interruption. With access only to a usually brief clinical comment on the request form, radiologists became less aware of the clinical situation. Robert Wachter noted:

“PACS left radiologists information rich but knowledge-poor.”

On later reflection, Lemke realized he had missed the impact of this technology on workflow and blamed himself “for not pushing the workflow issue in the beginning.”

However, despite the affect on workflow, a consensus was developing: “The advantages of PACS are so vast that few would want to turn back the clock.”

Challenges: Nighthawks, lower reimbursement, and artificial intelligence

PACS opened the possibility for a facility to contract image analysis with radiologists in another time zone, referred to as “nighthawks.” While allowing welcomed sleep for the local radiology team, the lower fees of a foreign radiologist raised concerns that hospitals would rely on those services exclusively. The current growth of ACO’s with their bundling of payments could further lower reimbursement.

Because of the increasingly complex, information-rich images being generated by modern imaging, PACS must continue to evolve. As Lemke describes:

“It is an open-ended spiral. Computers and communications in the scanners generate vast amounts of data, so we need more computers and communication systems to process the data and display the images to radiologists and other clinicians. This is a never-ending process.”

The biggest future challenge, however, comes from the ongoing digital revolution itself. Computer-aided detection and diagnosis using machine learning (so called “deep learning”) is now possible and raises concern about “replacement by the machine.” Fortunately, for most disorders, “the combination of human and machine interpretation seems to perform better than either one.”

Radiologists respond to the disconnection with clinical colleagues

Radiologists are moving closer to the site of need – such as the ER, ICU, or interventional suite – to foster greater interaction with their clinical colleagues. Robert Wachter noted:

“We have to act more like consulting physicians … to look at the appropriateness of the requests for advanced imaging studies … rather than just going ahead and doing the study.”

Radiologists are also contributing to interdisciplinary conferences among the specialties involved in the patient’s care. Communication among clinical colleagues through PACS itself is currently under development.

Despite the challenges ahead, digital imaging through PACS has so successfully transformed the quality of image evaluation and management that a return to a film system is unthinkable.

While initially “frightening,” in 3 decades PACS became the imaging foundation of modern medicine. As Lemke concludes:

“It is a sign of the times. The idea of PACS is not so weird and frightening any more.”

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