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Achieving 4D MRI in Regular Breathing Cycle with Extended Acquisition Time of Dynamic MR Images

C Hui

C Hui1*, Z Wen2 , B Stemkens3 , R Tijssen4 , C van den Berg5 , S Beddar6 , (1) UT MD Anderson Cancer Center, Houston, TX, (2) MD Anderson Cancer Center, Houston, TX, (3) UMC Utrecht, Utrecht, Utrecht, (4) University Medical Center Utrecht, Utrecht, Utrecht, (5) University Medical Center Utrecht, Utrecht, Utrecht, (6) UT MD Anderson Cancer Center, Houston, TX


SU-F-303-2 (Sunday, July 12, 2015) 4:00 PM - 6:00 PM Room: 303

Purpose: The purpose of this study is to develop a technique to obtain four-dimensional (4D) magnetic resonance (MR) images that are more representative of a patient’s typical breathing cycle by utilizing an extended acquisition time while minimizing the image artifacts.

Methods: The 4D MR data were acquired with the balanced steady state free precession in two-dimensional sagittal plane of view. Each slice was acquired repeatedly for about 15 s, thereby obtaining multiple images at each of the 10 phases in the respiratory cycle. This improves the probability that at least one of the images were acquired at the desired phase during a regular breathing cycle. To create optimal 4D MR images, an iterative approach was used to identify the set of images that yielded the highest slice-to-slice similarity. To assess the effectiveness of the approach, the data set was truncated into periods of 7 s (50 time points), 11 s (75 time points) and the full 15 s (100 time points). The 4D MR images were then sorted with data of the three different acquisition periods for comparison.

Results: In general, the 4D MR images sorted using data from longer acquisition periods showed less mismatched artifacts. In addition, the normalized cross correlation (NCC) between slices of a 4D volume increases with increased acquisition period. The average NCC was 0.791 from the 7 s period, 0.794 from the 11 s period and 0.796 from the 15 s period.

Conclusion: Our preliminary study showed that extending the acquisition time with the proposed sorting technique can improve image quality and reduce artifact presence in the 4D MR images. Data acquisition over two breathing cycles is a good trade-off between artifact reduction and scan time.

Funding Support, Disclosures, and Conflict of Interest: This research was partially funded by the the Center for Radiation Oncology Research from UT MD Anderson Cancer Center.

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