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Effects of Breathing Irregularity On Tumor Motion Measurement of 4D-MRI: A Comparison Between Cine and Sequential Image Acquisition Modes

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Y Liu

Y Liu1*, F Yin2 , D Rhee3 , J Cai2 , (1) Medical Physics Program, Duke University, Durham, NC, (2) Duke University Medical Center, Durham, NC, (3) Dongnam Institute of Radiological and Medical Sciences, Gijang-gun, Busan,


WE-G-18C-3 Wednesday 4:30PM - 6:00PM Room: 18C

We have recently developed a cine-mode T2*/T1-weighted 4D-MRI technique, and a sequential-mode T2-weighted 4D-MRI for imaging respiratory motion . The latter has better tumor-contrast due to its T2-weighting. This study aims at investigating which 4D-MRI image acquisition mode, cine or sequential, provides more accurate measurement of respiratory motion.

A 4D Digital Extended Cardiac-Torso (XCAT) human phantom with a hypothesized tumor was used to simulate image acquisition and 4D-MRI reconstruction. Tumor was set to move continuously with a given breathing signal. Its trajectories were measured from both sequential- and cine-mode 4D-MRI. Comparisons of measurements with the average tumor trajectories calculated from the input profile as references were conducted. Absolute tumor motion amplitude differences (D) were determined.
A total of 500 simulated respiratory profiles with a wide range of irregularity were used to investigate the relationship between D and Ir. Statistical analysis of D for breathing profiles of 20 real cancer patients were conducted with a sign rank test regarding two modes. Lastly, we investigated the possibility of further improving motion measurement accuracy in sequential-mode 4D-MRI by removing data points of high irregularity. An irregularity filter was applied to the same 20 patients. Sign rank tests for D of sequential-mode with filter and cine-mode were performed.

D increased faster for cine-mode (D=0.37*Ir) than sequential-mode (D=0.16*Ir) as irregularity increased. For 20 cancer patients, D was 0.12cm and 0.10cm for cine- and sequential-modes on average; p-value was 0.0228. Removing highly irregular data points increased accuracy of tumor trajectory for sequential-mode 4D-MRI, D was decreased by 10%. P-value was 0.0065.

Tumor motion measurement is more accurate and less susceptible to breathing irregularity in sequential-mode 4D-MRI than that in cine-mode 4D-MRI; its accuracy could be further improved in sequential-mode 4D-MRI by selectively removing data points of high irregularity.

Funding Support, Disclosures, and Conflict of Interest: NIH (1R21CA165384-01A1)

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