Philipp Lang MD, MBA, PRESENTER: Nothing to Disclose

Abstract: HTML Purpose: The purpose was to evaluate a single-slab 3D FSE sequence for cartilage imaging and compare it with 3D SPGR sequences with a water-selective spectral spatial pulse (3D SS-SPGR) and standard fat-saturated 3D SPGR images. Methods and Materials: Eight volunteers were evaluated with 3D FSE, 3D SS-SPGR and standard 3D SPGR pulse sequences. Imaging was performed with a 3.0T whole body MRI scanner equipped with high-speed gradients (GE Medical Systems, Milwaukee, WI). A phased array RF knee coil was used (USA Instruments, Aurora, OH). The 3D FSE sequence utilizes a single-slab technique with hard pulses for the excitation and for the refocusing RF pulses. This results in very small effective echo time and echo spacing. All 3D FSE images were acquired with TR/TE in msec 370/4.3, echo train length of 10, 0.5-mm slice thickness, 192 slices, matrix 256x200, FOV 120mm, bandwidth 62.5kHz, 1 NA, fat-saturation. 3D SS-SPGR images were acquired with TR/TE/flip/angle of 28.4/8.9°, 1.5 mm sections, 64 slices, matrix 512x256, FOV 120 mm, bandwidth 16kHz, and 1 NA. Standard 3D SPGR images were acquired with 60/5/40°, 1.5-mm slice thickness, 64 slices, matrix 512x192, FOV 120mm, bandwidth 16kHz, 1 NA, fat-saturated. SNR and CNR were normalized for scan time and voxel volume. Summary statistics for (1) SNR and (2) CNR were computed respectively for each pulse sequence. Results: The 3D FSE technique demonstrated normalized SNRs that were twice as high as those achieved with 3D SPGR. Cartilage SNRs (mean [SD]) were: 3D FSE 103.26 [27.33], 3D SS-SPGR 63.85 [37.36], and 3D SPGR 57.49 [6.28]. Normalized CNR between cartilage and fluid was substantially higher with the 3D FSE technique when compared with 3D SS-SPGR and 3D SPGR. Cartilage-fluid and cartilage-menisci CNRs were; 3D FSE 81.96 [22.28] and 39.12 [26.05], 3D SS-SPGR 52.84 [24.28] and 44.77 [2.49], and 3D SPGR 51.09 [5.28] and 24.98 [1.51]. Conclusion: Single-slab 3D FSE acquisition yields high SNR and eliminates unwanted magnetization transfer and boundary image artifacts. Blurring was not a significant problem with our 3D FSE sequence; the sequence utilizes hard pulses which enable ultra-short echo times thereby significantly reducing blurring artifact that can be encountered on standard FSE sequence using soft pulses and long echo times. A valuable advantage of the 3D FSE sequence is its near isotropic resolution. Images can be displayed in any desired plane without apparent loss in image quality thereby reducing partial volume artifacts and resultant errors in visual and quantitative assessment of the cartilage.       Questions about this event email: pklang@partners.org

Lang MD, MBA, P, Cartilage Imaging at 3.0T: Comparison of Standard 3D SPGR with 3D Spectral Spatial SPGR and 3D FSE Sequences.  Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL. http://archive.rsna.org/2003/3106634.html