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Abstract #4648

Assessment of Hyperpolarized Gas Ventilation Defect Percentage via User-defined Defect Thresholds

Gabriela Maria Garcia Delgado1, Cody Thornburgh2, Ummul Afia Shammi3, John Mugler III4, Jaime Mata4, Mu He4, Wilson Miller4, Talissa A Altes2, and Robert P Thomen1,2
1Chemical and Biomedical Engineering, University of Missouri, Columbia, MO, United States, 2Radiology, University of Missouri, Columbia, MO, United States, 3Biomedical Engineering, University of Illinois, Chicago, IL, United States, 4Department of Radiology and Medical Imaging, University of Virginia, Charlottesville, VA, United States

Synopsis

Keywords: Hyperpolarized MR (Gas), Hyperpolarized MR (Gas)

Motivation: A common endpoint of Hyperpolarized Gas MRI (HPG) is the ventilation defect percentage (VDP), but the signal threshold which defines ventilation defects differs among published techniques.

Goal(s): Allow a human reader to manually choose a threshold which best identifies ventilation defects and assess the method which best represents the selection.

Approach: A custom GUI program was developed and 65 HPG cases were evaluated by multiple readers. The selected threshold values were compared with those of commonly used techniques.

Results: The reader thresholds were often lower than those of published techniques for lower-VDP cases and higher in higher-VDP cases.

Impact: Single-threshold VDP methods are often discordant with human reader selection of defect thresholds. The extent to which defect mis-labeling is acceptable differs substantially between researchers and radiologists. Defect maps should always be evaluated visually and mis-labeled voxels corrected if necessary.

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