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Improved Airway Measurement Accuracy for Low Dose Quantitative CT (qCT) Using Statistical (ASIR), at Reduced DFOV, and High Resolution Kernels in a Phantom and Swine Model

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A Rodriguez

A Rodriguez1*, F Ranallo1 , P Judy2 , D Gierada3 , S Fain1 , (1) University of Wisconsin, Madison, WI, (2) Brigham and Women's Hospital, Boston, MA, (3) Washington University, St Louis, MO


TU-A-12A-11 Tuesday 7:30AM - 9:30AM Room: 12A

Purpose: To improve the accuracy of airway measures and reduce x-ray dose in quantitative CT (qCT) of the lung.

Methods: qCT was performed on an airway phantom (COPD gene) and a swine model. The airway phantom was used to identify expected improvements in spatial resolution and noise tradeoffs for choice of CT reconstruction kernel and display FOV (DFOV). Results in the phantom were then applied to the swine model. Images were obtained via helical scans that were performed using a GE Discovery CT750 HD with the COPD Gene/SARP protocols except tube current was varied from 790 to 50 mA, and lung inflation was fixed via mechanical ventilator. CT data were reconstructed using STANDARD (Std) and Bone reconstruction kernels for FBP and 100% ASIR at half and full DFOV. Inner Diameter(ID) and wall area percent (WA%) of selected airway sizes were matched across the swine lung and phantom and performed using Airway Inspector (Surgical Planning Laboratory, Brigham and Women's Hospital, Boston, MA). For the swine lung the CT acquisition at 790 mA with ASIR and Bone kernel at half DFOV parameters was the reference standard for comparison to the lower dose scans.

Results: The accuracy of the ID and WA% improved by ~24% and ~23% for half DFOV with the Bone kernel and ASIR reconstruction for both phantom and swine models for all airways investigated. For low dose qCT, the difference between the reference standard measures and the measures obtained with half DFOV with Bone+ASIR remained much lower than those using current clinical parameters (FBP at full DFOV) even at one fourth the dose for all airways investigated as is shown in Table 1.

Conclusion: The combination of ASIR with higher spatial resolution reconstruction shows promise to reduce x-ray dose and improve qCT of lung airways.

Funding Support, Disclosures, and Conflict of Interest: NIBIB PB EB 1010 159 JKS Recovery Quantitative Imaging Biomarker Alliance (QIBA) U10 HL109168 SARP

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