Comparison of 1.5T and 3T MRI scanners in evaluation of acute bone stress in the foot

Ten patients with 12 stress fractures seen on plain radiographs underwent MRI using 1.5T and 3T scanners. T1 FSE and STIR axial, sagittal, and coronal view sequences were obtained. Two musculoskeletal radiologists interpreted the images independently and by consensus in case of disagreement.Of the 63 acute bone stress changes seen on 3T images, 61 were also seen on 1.5T images. The sensitivity of 1.5T MRI was 97% (95% CI: 89%-99%) compared with 3T. The 3T MRI images where, therefore, at least equally sensitive to 1.5T scanners in detection of bone marrow edema. On T1-weighted sequences, 3T images were slightly superior to 1.5T images in visualizing the demarcation of the edema and bone trabeculae. The kappa-value for inter-observer variability was 0.86 in the MRI indicating substantial interobserver agreement.Owing to slightly better resolution of 3T images, edema characterization is easier, which might aid in the differential diagnosis of the bone marrow edema. There was, however, no noteworthy difference in the sensitivity of the 1.5T and 3T images to bone marrow edema. Routine identification of acute bone stress changes and suspected stress injuries can, therefore, be made with 1.5T field strength.MRI plays an important roll in the diagnosis of stress fractures and in imaging acute bone stress changes in bone [1]. In the foot, MRI offers an accurate means of identifying acute bone stress changes in the small bones [2]. Recent advances in 3T MRI systems offer significant advantages for musculoskeletal imaging [3-5]. The better signal-to-noise ratio can be utilized in imaging ligaments and cartilages as well as meniscal structures of the knee [6-8]. Some previous studies of the knee [9-11] indicate the 3T images have excellent sensitivity and specificity for detecting meniscal tears and ACL ruptures compared to arthroscopy.In the foot, high quality 3T MRI images enable accurate diagnosis of collateral ligament and syndesmosis injuries [12]. The foot is a suitable s