Dr. Michael Froehler Profile

Dr. Michael Froehler

at Vanderbilt Univ Medical Ctr

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Publications (1)

Proceedings Article | 15 February 2021 Presentation + Paper

A novel approach to calculating dual energy in the angiography suite

Julie DiNitto, Juan Carlo Ramirez-Giraldo, Michael Froehler

Proceedings Volume 11595, 115950V (2021) https://doi.org/10.1117/12.2581747

KEYWORDS: Iodine, Dual energy imaging, Blood, Angiography, Tin, Manufacturing, Ischemic stroke, Computed tomography, Calibration, Blood pressure

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Purpose: Medical management after endovascular treatment (EVT) for acute ischemic stroke involves blood pressure management and antithrombotic medications which are strongly influenced by hemorrhagic complications of the procedure. In this study our aim is to modify a commercially available c-arm angiographic system to assess feasibility of distinguishing between blood and iodinated contrast using dual-energy CT technology. Methods: An angiographic C-arm system was manipulated with the addition of a flat sheet of tin (Sn) filtration with corresponding calibration. Two flat-panel cone-beam CT (FP-CBCT) were acquired at 70 kV and 125Sn kV. A multienergy CT phantom with iodine inserts at various concentrations ranging from 0.2 to 15 mg/cc was used to characterize the behavior (i.e. dual-energy ratios DER) of the materials as a function of the kVp pair. DER values were needed to adjust an existing material decomposition software. The accuracy of iodine quantification was assessed with inserts including solid water, iodine, blood and mixed iodine and blood; all with concentrations ranges relevant for stroke imaging. Results: Imaging indicated the ability to differentiate between blood and iodine for the use with FP-CBCT. Pure blood and iodine inserts fell within the 95% confidence interval for precision of contrast concentration measured. For iodine inserts, the error from expected measurement was 7.5% or under for inserts with concentrations above 2 mg/cc. Inserts containing a combination of blood and iodine were consistently reading 1 mg/ml or less deviations relative to the value of the material specified by the manufacturer, which represented a 25-35% error difference from the expected value. Conclusion: These results establish the reproducibility of the phantom values for dual energy calculations and suggest that this technology may be clinically useful after EVT for stroke. Improvements in the accuracy of the iodine/blood combination under dual energy evaluation is needed for other applications outside of the use for differentiating between hemorrhage and contrast staining.

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