Feature
A decade of experience shows what makes an implementation
work, what needs to be done
by James H. Thrall, M.D., and
Keith J. Dreyer, D.O., Ph.D.
Oct 9, 2003
The hot debate over the last decade
was whether to acquire PACS. Now the question is simply how best to do it.
Collective experience from early adopters is invaluable for optimizing PACS
performance.
One of the most important lessons of the last decade is that the original
conceptualization of PACS was far too limited. Visionaries of 20 and 30 years
ago imagined the all-digital radiology department but did not envision the
all-digital medical enterprise, with ubiquitous hospital networks and
electronic medical records. Consequently, many early commercial PACS were
designed as closed systems for the all-digital radiology department.
Departments with these PACS have struggled to achieve fluid, rapid, and
user-friendly enterprise image distribution. PACS design now centers on Web
technology, which greatly facilitates the enterprise distribution requirement.
Resolution of the issue of enterprise image distribution is vital, and it must
be accomplished before significant cost savings from reduction in film
utilization can be realized. The goal in enterprise image distribution is a
system that is integrated into the institution's electronic medical record, so
that it is transparent to the clinician user at the point where images and
reports are actually archived. Commercial PACS companies have been slow to recognize
the importance of this level of integration, viewing their own respective
systems as stand-alone.
The advent of PACS has also highlighted the central role and importance of the
radiology information system. It is now clear that a sound, well-functioning
RIS is a prerequisite to successful installation of PACS. Ideally, the RIS
should be robustly integrated with the HIS, so that the hospital or enterprise
master patient index (MPI) or central patient registration system can serve as
the single "source of truth" for all patient demographic information.
Institutions that have installed PACS without a RIS and/or without using a
single MPI invariably struggle with misidentified patient records. This greatly
reduces the functional value of the PACS and increases the risk of lost data.
Medical legal exposure ensues. Experience has shown that it is better to take
care of RIS issues and RIS/HIS integration first, even bearing the cost and
time of replacing an outdated RIS if necessary, before embarking on PACS. As
illustrated in the figure on page 31, the RIS is the "quarterback"
for information management in radiology departments. A good PACS in no way
substitutes or makes up for a bad RIS.
The historic inability to transfer patient and study information directly from
the RIS to the respective imaging modalities is another major integration
issue. The lack of a direct electronic connection from the RIS to a CT scanner
or other imaging device requires technologists to reenter patient names and
registration numbers at the console. This not only takes time and effort but is
fraught with error. Mistakes in patient identification at the imaging device
persist in the PACS, resulting in cases that cannot be resolved between the
PACS and RIS. These cases stay in limbo until a PACS technologist can track
down the mistake so the patient is correctly identified in the system. If cases
are allowed to go into the PACS with identification errors, the patient records
may be unretrievable. This comes as a shock to new PACS users. How can cases be
"lost" in a computer!
Most digital imaging devices now being produced allow for the direct
transmission of patient and study information from the RIS to the modality,
resulting in error-free identification of the patient throughout the imaging
process. Hospitals and radiology departments should recognize that optimum PACS
performance will not be achieved until all imaging devices are converted to
systems that allow electronic connectivity with the RIS, and through the RIS to
the MPI.
We have coined the term "electronic round-trip" to describe the ideal
goal of total connectivity from electronic order entry to electronic delivery
of reports and images to referring physicians. Such electronic connectivity
eliminates errors and reduces work effort. All patient identification data come
from the MPI and are never reentered by hand at any step of the process. The
goal is not just to install a PACS but to integrate it fully into the digital
healthcare enterprise.
FINANCIAL INVESTMENT
One interesting debate over the last decade has been whether PACS pays for
itself with a positive return on investment or costs money in perpetuity with a
negative ROI. The good news is that more and more hospitals regard this
question as moot. These institutions see PACS as the imaging component of the
electronic medical record and recognize the positive functional impact. They
see no reason to deny clinicians electronic access to image data when they are
investing heavily in hospital information systems and electronic medical
records. The bad news is that other institutions persist in looking at ROI.
The literature is split about whether PACS pays for itself, largely because
methodologies, assumptions, and local conditions used in the analysis vary
widely. The table on page 34 outlines a number of the factors that allow
equally expert people to come to very different conclusions about PACS ROI.
Hospitals that have already invested in physician workstations and associated
networks suitable for PACS typically do not attribute these costs to PACS.
Likewise, hospitals that have already recognized the quality and productivity
benefits of computed radiography and direct capture digital radiography
attribute these costs to the normal radiology capital replacement and upgrade
process. Hospitals with suitable networks and clinician workstations in place
are likely to greatly reduce the amount of film production and realize major
savings from the cost of film, film processing, and film handling. Departments
with high volumes of CT and MRI show the greatest benefit from reduced filming,
while hospitals dominated by plain radiography benefit the least. The threshold
costs for installing PACS favor a positive financial return for larger versus
small institutions. Hospitals that implement voice recognition at the same time
as PACS realize additional cost savings from eliminating the transcription
process.
As indicated in the table, there are opposite ways to keep score for each of
the parameters. Some institutions lack the cultural will to reduce the use of
hard-copy film, or they may not have the network and desktop computer
availability needed to deliver images to clinicians electronically, and this
keeps them from realizing savings. By looking at these issues one by one and
then carefully assessing how a particular ROI calculation has been made, it is
easy to understand how conclusions differ. In the end, like many other
financial analyses, there is no absolute right and wrong absent the assumptions
that one institution decides to make versus another. Clearly, if all of the
issues are tipped in favor of a positive ROI, PACS is a big winner. Likewise,
if they are tipped to the negative, PACS will be a perpetual loser financially.
In particular, assumptions about the number and kinds of workstations required
are major drivers of cost differences between PACS installations. We had a
relatively modest budget to install PACS at MGH for a department performing
more than 500,000 examinations per year. We were forced to find alternative
solutions to simply adding more $40,000 reading devices at each state of
implementation and found it essential to separate the display software
application from the commodity display hardware to achieve serious savings in
this area. Once separated, the software and hardware can be purchased and
negotiated individually. While it is unlikely that a display application vendor
other than the institution's PACS vendor would be chosen, software-only display
applications can often be purchased through more affordable licensing methods
from the same PACS vendor (e.g., software-only site licensing, browser access
licensing, concurrent user licensing). Display hardware can be purchased from
myriad manufacturers at a wide variety of costs and performance specifications
and selected for its intended purpose: primary interpretation, clinical review,
operating room viewing, office review, resident review, or technologist review.
Typically, cost savings are tremendous.
WORKFLOW AND ARCHIVES
Workflow is a central PACS issue that was poorly understood 10 years ago and is
still very much a work-in-progress. In a smaller work environment, or in a
general radiology practice where everyone reads everything, workflow may not be
such an issue. As departments get larger and the degree of subspecialization
becomes more defined, workflow issues become magnified. The basic problem is to
match each case coming through the PACS with the work list of a radiologist
capable and responsible for interpreting that particular case or category of
case.
One practical example that comes up routinely involves grouped or associated
procedures such as a chest CT, abdominal CT, and pelvic CT-all obtained at one
time from a single patient. In many subspecialized departments, the chest CT would
be read by one radiologist and the abdominal and pelvic CTs by another. The
PACS must have the intelligence built into it to allow these procedures to show
up on two different work lists. Optimization of PACS requires transparent
access to cases by the right radiologist, with all cases accounted for. The
ease of accomplishing this, which varies greatly between systems, is worth
considering.
Lower cost archives with improved performance are helping address workflow
issues. It is now feasible to have far more of the total database immediately
available online than it was five or 10 years ago. In the past, a PACS
technician would have to pull prior images off a long-term archive to make them
available for comparison with a current case. Now, however, old cases are
available with the same speed and convenience as more recent ones, making the
process completely transparent to the end user where the images are being
stored. A 15-month archive available immediately online has turned out to be
the practical minimum for optimum workflow. This minimum encompasses most
episodes of acute illness and anything done at one-year follow-up. Obviously,
more is always better.
One implication of faster archive response coupled with faster networks is the
ability to access images on demand instead of requiring them to be pushed to a
local cache first to allow rapid viewing. In a large department, the need to
push images to workstations creates nothing short of a nightmare. To which and
how many workstations should a study be sent? How do you guarantee availability
of prior exams? How do you prioritize urgent cases? How do you know where each
radiologist will be? Even though challenging aspects to sorting out workflow
strategies remain, fast system response is the key. It allows cases to be
"pulled" instead of "pushed," which reduces network traffic
and permits great flexibility in parceling out cases to radiologists.
WORKSTATION FUNCTIONS
Parallel developments in image manipulation, including 3D renderings and
computer-aided diagnostic applications, highlight another fundamental watershed
in PACS development. Until now, all special image processing has typically
required separate dedicated workstations, since most PACS companies have not
provided image processing tools on their workstations beyond simple windowing,
leveling, measurement and magnification tools, and some rudimentary 3D
visualization techniques such as maximum intensity projection and multiplanar
reformatting, thereby limiting what radiologists can do online. Sophisticated
3D and CAD analysis is now mostly done offline with specific 3D application
software. This creates logistical problems in matching up the processed images
with the original data sets. Many institutions, including MGH, simply append
the processed images to the respective PACS files. This is clumsy and typically
does not permit dynamic viewing of 3D renderings.
The open question now is whether advanced image processing will be incorporated
in the PACS workstation with full utility available to the end user, either
clinician or radiologist. For the full potential of image postprocessing to be
realized, far more functionality must become available on the PACS workstation.
PACS vendors-by their incorporation of exogenous 3D applications into their own
PACS application software-are making increased functionality more available.
POOR COUSINS
Education, training, and system support are probably the poor relations in the
entire PACS story to date. It is amazing that hospitals will invest hundreds of
thousands and even millions of dollars in systems and routinely underestimate
the training needs of support staff. An important lesson of the last 10 years
is that PACS is not a turnkey system. It requires constant maintenance and
vigilance to keep up and running. Servers crash, networks go down, workstations
fail. Radiology departments will be well served to negotiate the right level of
support internally from the hospital information services department and
externally from the PACS vendor. Radiologists become frustrated and lose trust
in technology that breaks down, especially if there is no prompt resolution.
Training is especially important for voice recognition. Of all the technologies
that have come into radiology departments, this is the most difficult to learn.
Radiologists who spend the time to truly train the system to their voices,
learn how to use templates and macros, and master all of the system
enhancements and shortcuts like voice recognition and would not go back to
conventional transcription. Radiologists who fail to fully engage and never
completely grasp the benefits of templates and macros will struggle with it and
feel that it slows them down.
As more radiologists change their work from film to workstation image viewing,
issues of work environment and ergonomics have also arisen. The ideal
configuration for keyboard, mouse, voice recognition system microphone,
diagnostic workstation monitors, and RIS/voice recognition monitor is still
definitely a work-in-progress. Poor ergonomics can lead to fatigue and promote
repetitive stress injury. Backlighting reduces effective image contrast, and
excessive ambient noise can interfere with voice recognition. In general, PACS
environments must be darker and quieter than film-based viewing environments.
Simply converting an old room is often not the best solution.
The least well appreciated major quality assurance issue in PACS is monitor
performance. The American College of Radiology has standards for monitor
performance and a suggested approach to testing monitors. This approach should
be incorporated into the routine maintenance program for any PACS, but it may
often be overlooked. As the field migrates from CRTs to flat-panel displays and
from medical-based to general-purpose devices, new methods and management
strategies for QA and QC of display devices will be needed.
The benefits of PACS and voice recognition are obvious and considerable. The
full realization of these benefits requires a systematic understanding of PACS
components and their interrelationships and, beyond that, the integration of
PACS into the digital healthcare enterprise.
Dr. Thrall is radiologist-in-chief, and Dr. Dreyer is vice chair of radiology,
both at Massachusetts General Hospital.