MRI of the foot and ankle: Diagnostic performance and patient acceptance of a dedicated low field MR scanner

The objective of this study was to compare Image quality and patient acceptance of a dedicated .2-T MR system and a 1.0-T whole body system. Forty-one consecutive patients referred for MRI of the foot or ankle were prospectively examined with a dedicated .2-T low field system and a 1.0-T whole body system. Images were evaluated qualitatively by two observers and quantitatively using signal-difference-to-noise ratios. The patients were interviewed with respect to positioning, examination time, noise, claustrophobia, confidence in the diagnosis, and willingness to repeat the examination, using a questionnaire. The qualitative score was significantly higher for the 1.0-T system (2.6 vs 2.2 for reader 1 [P = .008] and 2.6 vs 1.7 for reader 2 [P < .0001]), respectively). The signal-difference-to-noise ratios were also superior for the 1.0-T MR system (2.96 vs .88, P < .0001). However, 96% of the lesions visualized at 1.0 T were also detected with the low field system. Patient acceptance was significantly better for the 1.0-T MR scanner (48.6 vs 43.9, P = .007). Image quality of the dedicated low held system was inferior to the 1.0-T system using objective parameters, and patients did not prefer the low field system. Although only 4% of lesions were missed in this series, the low held MR system can only be recommended when funding is limited and the available space is limited.