title: Bone marrow oedema assessment by magnetic resonance imaging in rheumatoid arthritis wrist and metacarpophalangeal joints: the importance of field strength, coil type and image resolution.
abstract: OBJECTIVE
  The aim of this study was to examine the influence of different MRI unit field strengths, coil types and image resolutions on the OMERACT RA MRI scoring system (RAMRIS) of bone marrow oedema (BME) and image quality.
  
  
  METHODS
  Forty-one patients and 12 healthy controls participated in this cross-sectional study. Coronal short tau inversion recovery (STIR) and T1-weighted sequences were obtained at 0.23, 0.6, 1.5 and 3T using flex coils (Flex). Additional STIR sequences were obtained with phased array extremity coils (Extr) (at 0.6 and 1.5T) and higher resolution (at 1.5T). In otal, 338 STIR image sets were anonymized and scored according to RAMRIS and parameters of image quality were measured.
  
  
  RESULTS
  The BME sum scores were similar overall when comparing the different MRI units, coil types and voxel sizes, yet significantly higher at the higher resolution of 1.5T Extr compared with 0.23T Flex (P = 0.004), 0.6T Flex (P = 0.03), 1.5T Flex (P = 0.05) and 3T Flex (P = 0.001). Mean differences were relatively minor (0-3.5). Intrareader reliability of BME scores was high [intraclass correlation coefficient ≥ 0.90 for all except 0.23T (0.81) and percentage exact agreement 81-88%]. The smallest detectable difference was better at 0.6, 1.5 and 3T (9-29% of maximum value) than at 0.23T (40%). Image quality was lowest at 0.23T.
  
  
  CONCLUSIONS
  No major, consistent differences were found between BME scores using STIR sequences obtained at different field strengths, coil types and image resolutions, suggesting that these are equally suited for assessment of BME in RA. However, parameters of image quality and intrareader reliability (favouring 0.6, 1.5 and 3T) should be considered when selecting the MRI acquisition strategy.
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark. simonkrabbe@gmail.com.
authors.forename: Simon
authors.initials: S
authors.lastname: Krabbe
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Iris
authors.initials: I
authors.lastname: Eshed
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Susanne Juhl
authors.initials: SJ
authors.lastname: Pedersen
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Pernille
authors.initials: P
authors.lastname: Bøyesen
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Jakob M
authors.initials: JM
authors.lastname: Møller
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Flemming
authors.initials: F
authors.lastname: Therkildsen
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Mette Bjørndal
authors.initials: MB
authors.lastname: Axelsen
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Ole Rintek
authors.initials: OR
authors.lastname: Madsen
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Copenhagen University Hospital Glostrup, Copenhagen, Denmark, Department of Radiology, Sheba Medical Center, Tel Hashomer, Israel, Department of Rheumatology, Diakonhjemmet Hospital, Oslo, Norway, Department of Radiology, Copenhagen University Hospital Herlev, Metropolitan University College Copenhagen and Department of Rheumatology, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors.forename: Mikkel
authors.initials: M
authors.lastname: Østergaard
mesh_terms: D000368:Aged; D001172:Arthritis, Rheumatoid / Q000473:pathology*; D001853:Bone Marrow / Q000473:pathology; D001855:Bone Marrow Diseases / Q000473:pathology*; D003430:Cross-Sectional Studies; D004487:Edema / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008662:Metacarpophalangeal Joint / Q000473:pathology*; D008875:Middle Aged; D015203:Reproducibility of Results; D014955:Wrist Joint / Q000473:pathology*
keywords: RAMRIS; arthritis; bone marrow oedema; magnetic resonance imaging; osteitis; rheumatoid arthritis