Program Information
Four-Dimensional MRI Method Based On Internal Respiratory Surrogate Derived by Dimensionality Reduction
J Uh1*, C Hua1 , (1) St. Jude Children's Research Hospital, Memphis, TN
Presentations
SU-F-303-8 (Sunday, July 12, 2015) 4:00 PM - 6:00 PM Room: 303
Purpose: To investigate the feasibility of constructing 4D MRI using non-navigator, image-based internal respiratory surrogate derived by dimensionality reduction (DR).
Methods: DR is a mathematical process that derives a series of scalar indices from the corresponding image frames. We proposed a novel image acquisition scheme (A) designed for the DR-derived internal surrogates (Wachinger, 2012) to better match the temporal pattern of previously established surrogates such as diaphragm position. The idea is to acquire a pair of slices alternatingly so the phase of a slice can be more accurately determined with additional information from the other slice. This scheme was compared with the sequential acquisition scheme (B), the navigator-based approach (C), and a previously proposed method using body area as internal respiratory surrogate (Cai, 2011) (D). Correlation between internal surrogates from all schemes and the diaphragm position was studied using a publicly available 4D MRI dataset (von Siebenthal, 2007).
Results: DR did not require any manual preprocessing. It took only a few minutes to process the entire 4D MRI data of 100 respiratory cycles with a common desktop computer. The respiratory surrogate signals were highly correlated with diaphragm positions. Correlation coefficients were 0.996, 0.993, 0.997, and 0.982 and mean absolute phase errors were 1.5%, 2.0%, 1.3%, and 3.3% for A, B, C and D, respectively. With the navigator-based approach C, the sampling rate of the regions of interest was reduced by half. Among those without the need for navigators, the novel acquisition scheme A reflected diaphragm positions better than the sequential scheme B and body area scheme D.
Conclusion: The proposed image-based 4D MRI method with a novel acquisition scheme and the DR-derived internal respiratory surrogate compared favorably to the navigator-based approach and has twice the sampling rate. Although tested on sagittal slices, it is potentially applicable to any slice orientation.
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