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Impact of Audiovisual Biofeedback Respiratory Training On 4D-CT Image Quality


T Yamamoto

T Yamamoto1,2*, S Gopalan1, J Berger1, E Johnston1, M Chung1, N Eclov1, M Diehn1, B Loo1, P Keall3, (1) Stanford University, Stanford, CA, (2) University of California Davis, Sacramento, CA, (3) University of Sydney, Sydney, Australia

SU-E-J-130 Sunday 3:00PM - 6:00PM Room: Exhibit Hall

Purpose: Current 4D-CT methods show artifacts of >4 mm in 90% of cases. The purpose of this study was to quantify the impact of audiovisual (AV) biofeedback respiratory training on 4D-CT image quality.

Methods: In an IRB-approved clinical trial, two 4D-CT scans, with free breathing and AV biofeedback, were acquired with a cine method for ten thoracic cancer patients. AV biofeedback was based on: (1) a patient-specific representative waveform and a dot moving according to the abdominal displacement, displayed on the video screen of the goggles; and (2) musical guides provided with a beat period corresponding to the waveform period. The phase-sorted 4D-CT images with free breathing and AV biofeedback at the 0% (peak-inhale), 30%, 50% (peak-exhale) and 80% phases were analyzed for artifacts by: (1) comparing normalized cross correlation (NCC)-based scores (artifacts give high scores) of the two images; and (2) quantifying a score for each pair based on visual assessment of the two image sets (positive scores mean that AV biofeedback 4D-CT is of higher quality). We tested the hypothesis that AV biofeedback significantly reduces 4D-CT artifacts using the two-tailed paired t-test.

Results: The impact of AV biofeedback varied widely with patients and phases, suggesting inconsistent patient compliance. For example, patient 5 demonstrated a visual assessment score of 4 at the 0% phase indicating that AV biofeedback 4D-CT was of higher quality than free breathing, while a score of -3 at the 50% phase indicating the opposite. Overall, no statistically significant differences were found in both the NCC-based score (free 0.60±0.32 vs. AV 0.65±0.27, p=0.32) and visual assessment score (0.0±2.7, p=0.95).

Conclusion: A 10-patient study demonstrated no statistically significant impact of AV biofeedback respiratory training on 4D-CT image quality. Future studies will investigate strategies to improve patient compliance by optimizing the biofeedback interface or increasing patient comfort.


Funding Support, Disclosures, and Conflict of Interest: NIH/NCI 2 R01 CA 093626; Stanford BioX Interdisciplinary Initiatives Program

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