Renxin Chu PhD, Presenter: Nothing to Disclose

Bruno Madore PhD, Abstract Co-Author: Nothing to Disclose

Lawrence P. Panych PhD, Abstract Co-Author: Nothing to Disclose

Stephan E. Maier MD, PhD, Abstract Co-Author: Nothing to Disclose

Parallel line scan diffusion imaging (LSDI) is a 1D Fourier encoding technique combined with parallel MRI. Increased acquisition speed comes virtually with no loss in SNR and minimal susceptibility and motion artifact. A diagonal interleaved scan scheme is employed for parallel LSDI in 3D. However, overlapping 90° and 180° excitations can produce unwanted echoes (cross-talk). Moreover, saturation artifacts (banding) may result from different saturation (steady state) in the first and successive interleaved scan sweeps. To address these issues, we apply gradient spoiler and a dummy scan to reduce these artifacts.

Parallel LSDI in 3D is implemented by employing cosine modulated 90° and 180° pulses which produce double slice excitation along y and z axes respectively and four simultaneously refocused columns are generated. Each from individual quadrants of the FOV. After 1D FFT, the four overlapping lines of image data can be obtained. Un-aliased 3D images can be obtained using SENSE-like algorithm. To reduce cross-talk artifacts, spoiling gradients are inserted in the end of X, Y, Z pulse waveform respectively. The polarity of spoiling gradient X, Y and Z changes along different sweep scheme. To maintain the same steady state in the first scan sweep as the successive ones, a dummy scan is performed before every first sweep.

Parallel LSDI pulse sequence with reduced artifact approach was implemented on a 3T GE Signa EXCITE short bore scanner. A GE distributed MRS sphere phantom was used to evaluate artifact with and without spoiling-gradient and dummy scan. The artifact usually become more severe in low b-value images than in high b-value images. Therefore, low b-value images were used to evaluate artifact. When gradient spoiling technique was employed, cross-talk artifact can be reduced dramatically. When dummy scan was applied, the banding artifact can be greatly reduced. A human study was performed and showed better image quality with reducing artifact techniques.

Parallel line scan diffusion imaging technique with addition of gradient spoiler and dummy scan can dramatically reduces cross-talk artifacts and saturation artifacts (banding artifact). {12712219817730}--> Supported by grant NIH U41RR019703 and R01 EB006867  

Parell LSDI can demostrate areas of white matter-related disease, such as stroke.

Chu, R, Madore, B, Panych, L, Maier, S, Reduced Artifact for Parallel Line Scan Diffusion Imaging.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9009625.html