2012 Proceedings - International Tissue Elasticity Conference

Special Topic
101 THE RADIOLOGICAL SOCIETY OF NORTH AMERICA’S QUANTITATIVE IMAGING
BIOMARKER ALLIANCE EFFORT TO DEVELOP AND VALIDATE CROSS-SYSTEM SHEAR
WAVE SPEED MEASUREMENTS FOR STAGING LIVER FIBROSIS.
Timothy J Hall 1 , Brian S Garra 2,3 , Andy Milkwoski 4 , Paul L Carson 5 , Dan Sullivan 6 ,
David Cosgrove 7 , Anthony Samir 8 , Claude Cohen–Bacrie 9 , Keith A Wear 3 , Mark L Palmeri 6 .
1 University of Wisconsin–Madison, Madison, WI, USA; 2 VA Medical Center, Washington, DC, USA;
3 Center for Devices and Radiological Health, US Food and Drug Administration, Silver Spring, MD,
USA; 4 Ultrasound, Siemens Healthcare, Mountain View, CA, USA; 5 University of Michigan, Ann Arbor,
MI, USA; 6 Duke University, Durham, NC, USA; 7 Imperial College, London, England, UK;
8 Massachusetts General Hospital, Boston, MA, USA; 9 Supersonic Imagine, Aix–en–Provence, FRANCE.
Background: We are undertaking development of a protocol and data analysis methods to allow direct
cross–platform comparison of shear wave speed (SWS) measurements in liver for staging fibrosis. Several
systems that measure SWS in the liver are commercially available, and several peer–reviewed
manuscripts report the ability to differentiate among fibrosis stages. However, there are many
confounding variables that produce substantial variability in quantitative SWS estimates including shear
wave spectrum, diffraction, tracking method, operator–related effects, patient motion and motion filters,
reflected waves and reflection filters, hemodynamics, measurement acceptance criteria and anatomy.
Providing a common SWS estimate result among systems would speed clinical adoption of the technology.
Aims: Our efforts are designed to determine the underlying system–related causes for differences in SWS
estimates and develop methods to allow direct cross–platform comparison of measurement results. In
addition, we intend to determine the major clinical and biological factors that significantly influence SWS
measurement and interpretation. We will develop a protocol for measurements that minimizes the
influence of system-related, clinical, and biological confounding factors.
Methods: The Radiological Society of North America (RSNA) has formed the Quantitative Imaging
Biomarker Alliance (QIBA) which is a consortium of researchers, healthcare professionals and industry
representatives who are collaborating to identify the barriers and solutions that would allow reliable,
valid, cross–platform quantitative measurements of clinically useful information from imaging methods.
The Alliance is organized by modality committees and within each modality committee is one or more
Technical Committee whose efforts involve developing a specific class of biomarker. Each Technical
Committee is supported by one or more Subcommittees that investigates and documents specific areas of
interest. The Ultrasound Modality Committee was formed in March 2012 and has a single Technical
Committee for Shear Wave Speed Measurement. Our first main goal is to reduce variability in SWS as a
noninvasive measure of liver fibrosis. We have a subcommittee to determine which phantom materials are
suitable for testing cross–platform SWS measurement performance and validating methods to
independently assess phantom material properties. A second subcommittee is determining why various
SWS measurement systems provide different results in the same media, how those measurements might
be directly compared and determining the range of valid measurement conditions. A third subcommittee
is tasked with determining the clinical and biological factors that influence SWS measurements and how
those factors might be mitigated. Together we will create a QIBA/UPICT (Uniform Protocol for Imaging in
Clinical Trials) protocol that specifies methods for data acquisition, analysis and interpretation as well as
a QIBA Profile that will provide specific claims of what can be accomplished by following the QIBA
Protocol. This QIBA Profile will also tell vendors how their system can be compliant with the profile. We
will then validate this profile across imaging systems with phantoms and volunteers and work with other
organizations such as drug and instrument companies and clinical trials organizations. We will forward
our profile to the FDA so that they can consider our recommendations for use in evaluating clinical trials
and approvals/clearances of quantitative measures.
Results: Practical phantom materials have been identified. Many system–dependent, clinical and
biological factors that can influence SWS estimates have been identified. Although we are just getting
started, we are well along the path to Protocol development.
Conclusions: A great deal of progress has been made in a few short months. We benefit significantly from
the involvement of some of the developers of these imaging system technologies.
Acknowledgements: The QIBA effort is funded in part by the RSNA and a contract with NIBIB
(HHSN268201000050C). The mention of commercial products, their sources, or their use in connection with material
reported herein is not to be construed as either an actual or implied endorsement of such products by the FDA.
indicates Presenter 81