Priorities
must focus on lobbying and otherwise encouraging imaging system
developers to build products that enable intraoperative integration.
In addition, purchasers must play a role in this effort by demanding
products that enable integration and intraoperability of imaging
systems.
The
full report of this Working Group appears below.
CHAPTER
6 :
INTRAOPERATIVE IMAGING
…THE REPORT OF WORKING GROUP 5
| PARTICIPANTS
Michael
Brazaitis, MD, Walter Reed Army Medical Center (Clinical
Leader)
Terry Peters, PhD, Robarts Research Institute (Technical
Leader)
Neal Clinthorne, PhD, Xoran Technologies, Inc.
Dorian Cojocaru, PhD, University of Craiova
Matthew Freedman, MD, MBA, Georgetown University Medical
Center
Warren Grundfest, MD, University of California at Los
Angeles
John Haller, PhD, National Institute of Biomedical Imaging
and Bioengineering
Ferenc Jolesz, MD, Brigham & Women’s Hospital
Ali Khamene, PhD, Siemens Corporate Research
Murray Loew, PhD, George Washington University
Micheal Marohn, MD, Johns Hopkins University
Calvin Maurer, PhD, Stanford University
Reuben Mezrich, MD, PhD, University of Maryland
Kensaku Mori, PhD, Nagoya University
Nassir Navab, PhD, Technical University of Munich
Sean O’Donnell, MD, Walter Reed Army Medical Center
Neil Ogden, MS, Food and Drug Administration
Frank Sauer, PhD, Siemens Corporate Research
Predrag Sukovic, PhD, Xoran Technologies, Inc.
Wolfgang Wein, Technical University of Munich
Kenneth Wong, PhD, Georgetown University Medical Center
Brad Wood, MD, NIH Clinical Center
Terry Yoo, PhD, National Library of Medicine
|
6.1
OVERVIEW: INTRAOPERATIVE IMAGING DEVELOPMENTS
Intraoperative
imaging encompasses the use of real-time imaging modalities
during the surgical procedure; the use of pre-operative images
registered to the patient; and all associated infrastructure
that is necessary to enable the effective use of such technologies.
This Working Group addressed the use of intraoperative and preoperative
imaging modalities including MRI and ultrasound, and the current
status of image fusion and registration. The group also discussed
visualization, image-guided surgery, tracking of instruments,
and the role of new modalities such as optical imaging for diagnosis
and for therapy.
The
need for integrated imaging systems and improved workflow in
today’s operating rooms (ORs) presents both key clinical
and technical issues. Poor information availability and information
flow from the imaging devices to the operating room are major
obstacles to improved intraoperative diagnosis and imaging.
This Working Group identified the presence of PACS (picture
archiving and communications) systems as almost an impediment
to the needs of surgeons. Many hospitals today have “bought
into” imaging, but in fact the imaging needs of surgeons
cannot be met with stationary PACS whose displays are typically
in 2D formats only. For surgeons, the imaging display must be
in 3D, be interactive, and also be displayed so the images can
be easily consulted by surgeons during a procedure. Functional
platforms for a range of equipment that can integrate real-time
data from imaging devices are required to meet intraoperative
needs, particularly as more complex surgeries are undertaken
today.
To
develop and use better intraoperative devices in the OR, experts
should identify particular tools, appropriate imaging modalities
for different surgical procedures, and skill sets that are required
for undertaking certain procedures. They should also focus on
the best ways to do a procedure using imaging technologies.
6.2 CLINICAL ISSUES: THE STATE OF INTRAOPERATIVE IMAGING
The
clinical need for increased use of imaging in the OR that is
acquired pre- as well as intraoperatively is driven by the increasing
desire to take advantage of minimally invasive procedures for
the treatment of disease throughout the human body. The goal
of being able to perform “therapy” at a target site
while avoiding the “surgery” necessary to gain access
to that site is a clear objective that can reduce patient trauma
and potentially decreases the cost of treatment delivery.
State
of imaging today. Intraoperative imaging technologies
that are currently available include ultrasound, endoscopes/laparoscopes,
nuclear probes, and gamma pens. These modalities are being used
possibly more so than magnetic resonance imaging (MRI) and computed
tomography (CT) at some leading U.S. institutions. In addition,
optical laparoscopic imaging is widely used and biologic spectroscopy
is being used particularly for certain applications such as
identifying cervical neoplasia.
However,
the integration capabilities of most available imaging modalities
are limited. Images acquired during a procedure are typically
neither integrated nor displayed with pre-operative images.
Imaging modalities are not used routinely in the OR.
Development
of the field. Access to integrated images that are
obtained prior to and during surgical procedures is key for
improving today’s surgeries. However, this need is not
shared by everyone in the medical community. In community hospitals,
for instance, which have limited imaging systems on hand, integration
is not only a non-issue, but the need for having and using new
imaging technologies is not voiced by older surgeons, who feel
that they already “know the anatomy.” More education
and training about the value of advanced imaging is therefore
warranted.
Furthermore,
tasks and staffing approaches must be adapted to multimodality
imaging environments. For instance, pre-planning and simulation
prior to surgery are necessary as 3D modeling should be done
prior to going into the OR. Therefore, surgical staffs must
be trained and well-versed in performing these pre-surgery functions.
In addition, more technical personnel need to be included on
the surgical team for operating the imaging equipment. Other
trained and educated OR staff, such as nurses and OR coordinators,
have to “buy in” to using the equipment and scheduling
its use. According to one Working Group member: “If [imaging
modalities] are difficult to use, people don’t use them
– the energy barrier is too great to simply have the image
show up.”
Operating
rooms themselves need to be reconfigured for more effective
use to be made of advanced imaging. This Working Group noted
that the traditional OR was not designed for today’s complex
workflow and for using complicated technology such as MRI or
CT. New designs are needed to obtain adequate intraoperative
visualization of integrated images. There is also a pressing
need to develop appropriate display systems (LCD panels, virtual
screens, and so on) that suit clinical needs in terms of size
and placement in the OR.
Figure
6: 3D laser ablation therapy
(courtesy of Ferenc Jolesz, MD, Brigham and Women’s Hospital)
6.3 TECHNICAL REQUIREMENTS: NEEDED IMPROVEMENTS IN IMAGING
QUALITY AND EFFICACY
Making
intraoperative imaging a clinically useful and welcomed option
requires technical teams of developers to address the following
needs.
1.
Improved image quality and image guidance. Intraoperative
imaging quality in its current state is deemed to be poor, overall.
Its adequacy is also in question. Particularly, this Working
Group noted that PACS systems (which are, in the main, tools
for radiologist to view medical images – not tools for
surgeons) available in the OR rarely have a 3D imaging capability
available. Typical PACS in the OR tend to simply duplicate the
“wall-of-film” approach used outside of the OR:
that is, they mimic the way plain films are displayed in the
radiology reading room. As such, they cannot meet the needs
of surgeons for intraoperative, real-time imaging and display.
Not
only improved quality but also improved image guidance systems
are needed to meet surgical requirements. PACS systems without
3D capabilities do not allow for routine surgical planning.
To illustrate this point, an example was provided indicating
the different imaging needs of radiologists and neurosurgeons
working with an aneurysm. Radiologists need to specifically
visualize the aneurysm, while surgeons must be able to visualize
the real-time surgical process. Therefore, surgeons need 3D
capabilities so that they can assess the aneurysm and blood
vessels from multiple dimensions and determine the surgical
directions that they must take.
2.
Improved reliability of image tracking. More reliable
tracking of images that are taken during surgical procedures
may be particularly helpful to meet the need for improved guidance
during surgeries. A related need is for an automated data keeping
system or book marking technique to identify and archive images
taken in MR, CT, and a variety of other imaging formats during
different phases of surgery.
3.
Improved registration techniques. Registration needs
must also be addressed by technical teams who should be tasked
with developing a standardized or common methodology. Vendor-specific
algorithms that are used today for some modalities are inadequate
for many purposes. Standardization of a universal imaging and
registration methodology is a key element on which to build
navigational systems (robotic or otherwise) that are able to
use registered data. Ideally, in addition, an advanced image-based
system may be developed that is smart enough to manipulate images
and co-register them, as needed.
4.
Improved segmentation process. Segmentation is seen
as an important part of intra-operative image utilization. First
and foremost, it needs to be applied to the 3D source images
in order to extract any sort of surface information from them,
for the purpose of registering images via surface matching,
or providing realistic organ visualization during the procedure.
However, segmentation is not a feature typically provided by
most commercial visualization packages. Segmentation also falls
into the category of “tampering with the data,”
in the sense that any rule applied to an image to define a surface
will inevitably compromise the data to some extent. It is clear
that universal segmentation algorithms are unlikely to ever
become entirely automatic. Hence there is a need for intuitive
interfaces to permit human intervention in the selection of
the desired region, as well as to provide an evaluation of the
consistency of the results.
Key
technical requirements in intraoperative diagnosis and imaging
are:
