Diffusion MRI

The main observation at the basis of our diffusion imaging work can be understood as follow. Diffusion-weighted imaging (DWI) involves acquiring several images of an object while varying the diffusion encoding, both in terms of how strong the encoding is (the strength is called ‘b-value’), and in terms of the direction in 3D that is being encoded (different directions are listed/indexed here using the letter ‘d’). The observation at the basis of our work is that if a Fourier transform is applied along both ‘b’ and ‘d’ directions, the result looks mostly empty:

 

Diffusion MRI

 

While there may be a lot of signal concentrated in the central cross-shaped region highlighted with dashed gray lines above, there is not much signal anywhere else. The idea here is to use this available real-estate, i.e., the four mostly-empty quadrants, to encode other information. Doing so, we can multiplex the density of the information and the effectiveness of the data acquisition process:

 

Diffusion MRI

 

We have applied this sort of trick to various types of DWI methods and sequences, such as HARDI, and we have applied it to different parts of the body, mostly the brain, optic nerve and the prostate. In all cases, our goal was to speed up the acquisition process so that images could be obtained that were less distorted, with better geometrical fidelity than a regular scan would have yielded. Furthermore, these better images could often be obtained in a fraction of the time a full scan would have required. Here is one particular example, for prostate imaging:

 

Diffusion MRI

 

 

Publications

  1. Aksit Ciris P, Chiou Jr-y, Glazer D, Zhang SH, Chao T-C, Tempany-Afdhal CM, Madore B, Maier SE. Accelerated segmented diffusion-weighted prostate imaging for higher resolution, higher geometric fidelity, and multi-b perfusion quantification. Invest Radiol 2019;54:238-46. PMCID: PMC6402959
  2. Chao TC, Chiou Jr-y, Maier SE, MadoreB. “Fast diffusion imaging with high angular resolution.” Magn Reson Med 2017; 77:696-706. PMCID: PMC4992669.
  3. Madore B, Chiou J-Y, Chu R, Chao T-C, Maier SE. Accelerated multi-shot diffusion imaging. Magn Reson Med 2014 Aug;72:324-36. PMCID: PMC3942374

Abstracts

  1. Aksit Ciris P, Chiou Jr-y, Glazer D, Zhang S-H, Chao T-C, Madore B, and Maier SE. “Accelerated segmented diffusion-weighted prostate imaging for higher resolution, higher geometric fidelity, and multi-b perfusion quantification.” Proceedings of the International Society of Magnetic Resonance in Medicine 2017. Honolulu, USA, p. 0112.
  2. Chang C-L, Chiou Jr-y, Wu M-L, Tsai S-Y, Maier SE, Madore B, Chao T-C. “To accelerate or not: An Investigation on the Tractography-based Diffusion Features for Fast Diffusion Imaging with High Angular Resolution.” Proceedings of the International Society of Magnetic Resonance in Medicine 2017. Honolulu, USA, p. 3349.
  3. Aksit Ciris P, Chiou Jr-y, Fedorov A, Tempany-Afdhal CM, Madore B, Maier SE. “Accelerated Segmented Diffusion-Weighted Prostate Imaging for Higher Resolution.” Proceedings of the International Society of Magnetic Resonance in Medicine 2016. Singapore, p. 5149.
  4. Chiou Jr-y, Madore B, Maier SE. “Accelerated Multi-Shot Diffusion Imaging in Optic Nerve.” Proceedings of the International Society of Magnetic Resonance in Medicine 2015. Toronto, Canada, p. 2305.
  5. Aksit Ciris P, Chiou Jr-y, Fedorov A, Tempany CM, Madore B, Maier SE. “Accelerated, Segmented Diffusion-Weighted Imaging in the Prostate to achieve High Resolution, Speed and Geometric Fidelity.” Proceedings of the International Society of Magnetic Resonance in Medicine 2015. Toronto, Canada, p. 3994.
  6. Chao T-C, Chiou Jr-y, Maier SE, Madore B. “High angularly resolved diffusion imaging with short scan time and low distortion.” Proceedings of the International Society of Magnetic Resonance in Medicine 2015. Toronto, Canada, p. 2940.
  7. Chao T-C, Chiou Jr-y, Maier SE, Madore B. “High Angularly Resolved Diffusion Imaging with Accelerated Multi-Shot Acquisition and Compressed Sensing.” Proceedings of the International Society of Magnetic Resonance in Medicine 2014. Milan, Italy: p. 0334.
  8. Madore B, Chiou Jr-y, Chu R, Chao T-C. “Accelerated multi-shot diffusion imaging.” Proceedings of the International Society of Magnetic Resonance in Medicine 2013. Salt Lake City, UT, USA, p. 2063.
  9. Madore B, Chiou Jr-y, Chu R, Chao T-C. “Acceleration strategy for navigated diffusion imaging.” Proceedings of the International Society of Magnetic Resonance in Medicine 2012. Melbourne, Australia, p. 1886.