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

• Published in: BMC musculoskeletal disorders Vol. 12; no. 1; p. 128
• Main Authors: Sormaala, Markus J, Ruohola, Juha-Petri, Mattila, Ville M, Koskinen, Seppo K, Pihlajamäki, Harri K
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 06.06.2011; BioMed Central; BMC
• Subjects: Accuracy; Age; Ankle; Biomechanical Phenomena; Bone marrow; Bones; Differential diagnosis; Edema; Edema - diagnosis; Edema - pathology; Equipment Design; Feet; Finland; Foot; Foot Bones - diagnostic imaging; Foot Bones - injuries; Foot Bones - pathology; Foot diseases; Foot Injuries - diagnosis; Foot Injuries - diagnostic imaging; Foot Injuries - pathology; Fractures; Fractures, Stress - diagnosis; Fractures, Stress - diagnostic imaging; Fractures, Stress - pathology; Humans; Inflammation; Injuries; Knee; Magnetic resonance imaging; Magnetic Resonance Imaging - instrumentation; Male; Military Personnel; Military service; Musculoskeletal diseases; NMR; Nuclear magnetic resonance; Observer Variation; Occupational Diseases - diagnosis; Occupational Diseases - diagnostic imaging; Occupational Diseases - pathology; Pain; Patients; Physiological aspects; Predictive Value of Tests; Radiography; Reproducibility of Results; Scanners; Stress, Mechanical; Young Adult; Finland
• ISSN: 1471-2474; 1471-2474
• DOI: 10.1186/1471-2474-12-128

Bone stress injuries are common in athletes and military recruits. Only a minority of bone stress changes are available on plain radiographs. Acute bone stress is often visible on MRI as bone marrow edema, which is also seen in many other disease processes such as malignancies, inflammatory conditions and infections. The purpose of this study was to investigate the ability of radiographs, 1.5T and 3T MRI to identify acute bone marrow changes 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.