EXPOSURE LIBRARIES
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OVERVIEW

MRIxViP

Overview Exposure Libraries

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More and more functionalized computational phantoms with progressively increasing resolution have become available in recent years. This development opens up for the first time the possibility to comprehensively analyze variations in the general population or for specific patient subgroups. However, such analyses take individual anatomical differences into consideration, and are thus computationally expensive, particularly for cases where the results must be verified and validated. Towards simplifying and standardizng routine evaluations, the IT’IS Foundation has begun to compile and make available comprehensive precomputed exposure libraries. The first libraries which are available focus on the incident fields required for evaluating the radiofrequency (RF) risk of magnetic resonance imagining (MRI) scanners and demonstrating the RF safety of implants during MRI scans. The libraries will be expanded and updated over time, and new libraries will be added as demanded by emerging new applications.

 

MRI Exposure Libraries for RF Safety Evaluation

IT’IS has precomputed two standard libraries of RF-induced electromagnetic fields (EMF) distributions inside the human body, resulting from exposure to a representative set of RF birdcage coils used in MRI scanners for 1.5T (MRIxViP1.5T) and 3T (MRIxViP3.0T). A good example of effective application of the libraries in evaluations is the IMAnalytics module recently released by our Z43 partner organization, ZMT Zurich MedTech AG. The integration of the libraries with the new module enables users to scale-up Tier 2 and 3 evaluations of implants without loss of full data traceability.

The libraries are based on birdcage model variations that cover all existing 1.5T and 3.0T closed-bore commercial MRI scanners. Each library consists of induced-field data from all relevant landmark positions simulated in eight anatomies of our popular Virtual Population (ViP) phantoms in the supine posture in 20 birdcage coils – for a total of more than 6,500 clinical scanning scenarios.

We will continue to expand the libraries to increase clinical coverage, evolving to encompass additional anatomies and clinically relevant postures other than supine as the data become available.

Specifications

  • 13’412 3D electric and magnetic field distributions at a resolution finer than 2x2x2 mm
  • 20 birdcage coils (10 for 1.5T and 10 for 3.0T, respectively) of different dimensions derived from a survey of existing 1.5T and 3.0T closed-bore commercial scanners
  • Eight different adult and pediatric ViP phantom models in the supine posture (Duke, Ella, Billie, Thelonious, Fats, Glenn, Louis, Eartha)
  • Head-to-foot imaging landmarks of the ViP models inside the RF coils, at 2.5 cm and 5 cm imaging steps for 1.5T and 3.0T, respectively