MR imaging of articular cartilage at 1.5T and 3.0T: Comparison of SPGR and SSFP sequences

SummaryObjectiveTo compare articular cartilage signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and thickness measurements on a 1.5T and a 3.0T magnetic resonance (MR) scanner using three-dimensional spoiled gradient recalled echo (3D-SPGR) and two 3D steady-state free precession (SSFP) sequences.MethodsBoth knees of five volunteers were scanned at 1.5T and at 3.0T using a transmit-receive quadrature extremity coil. Each examination consisted of a sagittal 3D-SPGR sequence, a sagittal fat suppressed 3D-SSFP (FS-SSFP) sequence, and a sagittal Dixon 3D-SSFP sequence. For quantitative analysis, we compared cartilage SNR and CNR efficiencies, as well as average cartilage thickness measurements.ResultsFor 3D-SPGR, cartilage SNR efficiencies at 3.0T increased compared to those at 1.5T by a factor of 1.83 (range: 1.40–2.09). In comparison to 3D-SPGR, the SNR efficiency of FS-SSFP increased by a factor of 2.13 (range: 1.81–2.39) and for Dixon SSFP by a factor of 2.39 (range: 1.95–2.99). For 3D-SPGR, CNR efficiencies between cartilage and its surrounding tissue increased compared to those at 1.5T by a factor of 2.12 (range: 1.75–2.47), for FS-SSFP by a factor 2.11 (range: 1.58–2.80) and for Dixon SSFP by a factor 2.39 (range 2.09–2.83). Average cartilage thicknesses of load bearing regions were not different at both field strengths or between sequences (P>0.05). Mean average cartilage thickness measured in all knees was 2.28mm.ConclusionArticular cartilage imaging of the knee on a 3.0T MR scanner shows increased SNR and CNR efficiencies compared to a 1.5T scanner, where SSFP-based techniques show the highest increase in SNR and CNR efficiency. There was no difference between average cartilage thickness measurements performed at the 1.5T and 3.0T scanners or between the three different sequences