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Fast High-Spatial-Resolution MRI of the Ankle with Parallel Imaging Using GRAPPA at 3 T

¹ Department of Radiology, University of California at San Francisco, San Francisco, CA.
² Present address: Department of Radiology, Institut für Röntgendiagnostik, Technische Universität München, Ismaninger Str. 22, 81675 München, Germany.
³ UCSF & UCB Joint Graduate Group in Bioengineering, Berkeley, CA.

View larger version (172K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1A —Spoiled gradient-recalled acquisition in the steady state (SPGR) images show grade 3 cartilage defect (arrowhead) in ankle of cadaver specimen. No significant difference in visualization of abnormality was found between normal (A) and parallel (B) acquisitions at 3 T.

View larger version (167K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1B —Spoiled gradient-recalled acquisition in the steady state (SPGR) images show grade 3 cartilage defect (arrowhead) in ankle of cadaver specimen. No significant difference in visualization of abnormality was found between normal (A) and parallel (B) acquisitions at 3 T.

View larger version (169K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 1C —Spoiled gradient-recalled acquisition in the steady state (SPGR) images show grade 3 cartilage defect (arrowhead) in ankle of cadaver specimen. Cartilage defect was not seen at 1.5 T by one of two radiologists.

View larger version (174K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2A —T1-weighted (A–C) and fat-saturated T2-weighted (D–F) images of ankle joint in cadaver specimen. Images show superior image quality at 3 T (A, B, D, and E) as opposed to 1.5 T (C and F). No significant difference in image quality or signal-to-noise ratio (SNR) was found between normal (A and D) and parallel (B and E) acquisitions at 3 T (p > 0.05). Mean values of image quality for T1-weighted sequences were as follows: 2.8 (1.5 T), 3.5 (3 T), and 3.5 (3 T with generalized autocalibrating partially parallel acquisition [GRAPPA] algorithm). Mean values of SNR for T1-weighted sequences were as follows 43.0 (1.5 T), 49.7 (3 T), and 47.2 (3 T with GRAPPA algorithm [3.0TGR]).

View larger version (174K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2B —T1-weighted (A–C) and fat-saturated T2-weighted (D–F) images of ankle joint in cadaver specimen. Images show superior image quality at 3 T (A, B, D, and E) as opposed to 1.5 T (C and F). No significant difference in image quality or signal-to-noise ratio (SNR) was found between normal (A and D) and parallel (B and E) acquisitions at 3 T (p > 0.05). Mean values of image quality for T1-weighted sequences were as follows: 2.8 (1.5 T), 3.5 (3 T), and 3.5 (3 T with generalized autocalibrating partially parallel acquisition [GRAPPA] algorithm). Mean values of SNR for T1-weighted sequences were as follows 43.0 (1.5 T), 49.7 (3 T), and 47.2 (3 T with GRAPPA algorithm [3.0TGR]).

View larger version (163K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2C —T1-weighted (A–C) and fat-saturated T2-weighted (D–F) images of ankle joint in cadaver specimen. Images show superior image quality at 3 T (A, B, D, and E) as opposed to 1.5 T (C and F). No significant difference in image quality or signal-to-noise ratio (SNR) was found between normal (A and D) and parallel (B and E) acquisitions at 3 T (p > 0.05). Mean values of image quality for T1-weighted sequences were as follows: 2.8 (1.5 T), 3.5 (3 T), and 3.5 (3 T with generalized autocalibrating partially parallel acquisition [GRAPPA] algorithm). Mean values of SNR for T1-weighted sequences were as follows 43.0 (1.5 T), 49.7 (3 T), and 47.2 (3 T with GRAPPA algorithm [3.0TGR]).

View larger version (143K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2D —T1-weighted (A–C) and fat-saturated T2-weighted (D–F) images of ankle joint in cadaver specimen. Images show superior image quality at 3 T (A, B, D, and E) as opposed to 1.5 T (C and F). No significant difference in image quality or signal-to-noise ratio (SNR) was found between normal (A and D) and parallel (B and E) acquisitions at 3 T (p > 0.05). Mean values of image quality for T1-weighted sequences were as follows: 2.8 (1.5 T), 3.5 (3 T), and 3.5 (3 T with generalized autocalibrating partially parallel acquisition [GRAPPA] algorithm). Mean values of SNR for T1-weighted sequences were as follows 43.0 (1.5 T), 49.7 (3 T), and 47.2 (3 T with GRAPPA algorithm [3.0TGR]).

View larger version (145K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2E —T1-weighted (A–C) and fat-saturated T2-weighted (D–F) images of ankle joint in cadaver specimen. Images show superior image quality at 3 T (A, B, D, and E) as opposed to 1.5 T (C and F). No significant difference in image quality or signal-to-noise ratio (SNR) was found between normal (A and D) and parallel (B and E) acquisitions at 3 T (p > 0.05). Mean values of image quality for T1-weighted sequences were as follows: 2.8 (1.5 T), 3.5 (3 T), and 3.5 (3 T with generalized autocalibrating partially parallel acquisition [GRAPPA] algorithm). Mean values of SNR for T1-weighted sequences were as follows 43.0 (1.5 T), 49.7 (3 T), and 47.2 (3 T with GRAPPA algorithm [3.0TGR]).

View larger version (114K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 2F —T1-weighted (A–C) and fat-saturated T2-weighted (D–F) images of ankle joint in cadaver specimen. Images show superior image quality at 3 T (A, B, D, and E) as opposed to 1.5 T (C and F). No significant difference in image quality or signal-to-noise ratio (SNR) was found between normal (A and D) and parallel (B and E) acquisitions at 3 T (p > 0.05). Mean values of image quality for T1-weighted sequences were as follows: 2.8 (1.5 T), 3.5 (3 T), and 3.5 (3 T with generalized autocalibrating partially parallel acquisition [GRAPPA] algorithm). Mean values of SNR for T1-weighted sequences were as follows 43.0 (1.5 T), 49.7 (3 T), and 47.2 (3 T with GRAPPA algorithm [3.0TGR]).

View larger version (127K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3A —31-year-old healthy male volunteer. Axial T1-weighted fast spin-echo images of foot show superior delineation of spring ligament (arrow) at 3 T (A and B) as opposed to 1.5 T (C); 3.0TGR = 3.0T with GRAPPA algorithm. No significant difference was found between (A) and parallel (B) acquisitions at 3 T; visualization of this ligament was rated very good at 3 T and as moderate at 1.5 T (C) by both radiologists.

View larger version (125K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3B —31-year-old healthy male volunteer. Axial T1-weighted fast spin-echo images of foot show superior delineation of spring ligament (arrow) at 3 T (A and B) as opposed to 1.5 T (C); 3.0TGR = 3.0T with GRAPPA algorithm. No significant difference was found between (A) and parallel (B) acquisitions at 3 T; visualization of this ligament was rated very good at 3 T and as moderate at 1.5 T (C) by both radiologists.

View larger version (117K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 3C —31-year-old healthy male volunteer. Axial T1-weighted fast spin-echo images of foot show superior delineation of spring ligament (arrow) at 3 T (A and B) as opposed to 1.5 T (C); 3.0TGR = 3.0T with GRAPPA algorithm. No significant difference was found between (A) and parallel (B) acquisitions at 3 T; visualization of this ligament was rated very good at 3 T and as moderate at 1.5 T (C) by both radiologists.

View larger version (45K): [in this window] [in a new window] [as a PowerPoint slide]   Fig. 4 —Line profiles of spoiled gradient-recalled acquisition in the steady state (SPGR) images of cadaver specimen suggest edge sharpness of conventional images and of generalized autocalibrating partially parallel acquisition (GRAPPA) images is comparable at 3 T. Gray region corresponds to cartilage. 3.0 TGR = 3.0T imaging with GRAPPA algorithm.

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