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- Title
Pre‐excitation gradients for eddy current nulled convex optimized diffusion encoding (Pre‐ENCODE).
- Authors
Middione, Matthew J.; Loecher, Michael; Cao, Xiaozhi; Setsompop, Kawin; Ennis, Daniel B.
- Abstract
Purpose: To evaluate the use of pre‐excitation gradients for eddy current–nulled convex optimized diffusion encoding (Pre‐ENCODE) to mitigate eddy current–induced image distortions in diffusion‐weighted MRI (DWI). Methods: DWI sequences using monopolar (MONO), ENCODE, and Pre‐ENCODE were evaluated in terms of the minimum achievable echo time (TE min$$ {}_{\mathrm{min}} $$) and eddy current‐induced image distortions using simulations, phantom experiments, and in vivo DWI in volunteers (N=6$$ N=6 $$). Results: Pre‐ENCODE provided a shorter TE min$$ {}_{\mathrm{min}} $$ than MONO (71.0 ±$$ \pm $$ 17.7ms vs. 77.6 ±$$ \pm $$ 22.9ms) and ENCODE (71.0 ±$$ \pm $$ 17.7ms vs. 86.2 ±$$ \pm $$ 14.2ms) in 100%$$ \% $$ of the simulated cases for a commercial 3T MRI system with b‐values ranging from 500 to 3000 s/mm 2$$ {}^2 $$ and in‐plane spatial resolutions ranging from 1.0 to 3.0mm 2$$ {}^2 $$. Image distortion was estimated by intravoxel signal variance between diffusion encoding directions near the phantom edges and was significantly lower with Pre‐ENCODE than with MONO (10.1%$$ \% $$ vs. 22.7%$$ \% $$, p=6−5$$ p={6}^{-5} $$) and comparable to ENCODE (10.1%$$ \% $$ vs. 10.4%$$ \% $$, p=0.12$$ p=0.12 $$). In vivo measurements of apparent diffusion coefficients were similar in global brain pixels (0.37 [0.28,1.45]×10−3$$ \times 1{0}^{-3} $$ mm 2$$ {}^2 $$/s vs. 0.38 [0.28,1.45]×10−3$$ \times 1{0}^{-3} $$mm 2$$ {}^2 $$/s, p=0.25$$ p=0.25 $$) and increased in edge brain pixels (0.80 [0.17,1.49]×10−3$$ \times 1{0}^{-3} $$ mm 2$$ {}^2 $$/s vs. 0.70 [0.18,1.48]×10−3$$ \times 1{0}^{-3} $$mm 2$$ {}^2 $$/s, p=0.02$$ p=0.02 $$) for MONO compared to Pre‐ENCODE. Conclusion: Pre‐ENCODE mitigated eddy current–induced image distortions for diffusion imaging with a shorter TE min$$ {}_{\mathrm{min}} $$ than MONO and ENCODE.
- Subjects
DIFFUSION measurements; EDDIES; ENCODING; DIFFUSION coefficients; DIFFUSION magnetic resonance imaging
- Publication
Magnetic Resonance in Medicine, 2024, Vol 92, Issue 2, p573
- ISSN
0740-3194
- Publication type
Article
- DOI
10.1002/mrm.30068