Bettina G Weiss1, Lucas M Bachmann2, Christian W A Pfirrmann2, Rudolf O Kissling2, Veronika Zubler2. 1. From the Department of Physical Medicine and Rheumatology, and Department of Radiology, Balgrist University Hospital; Medignition Inc. Research Consultants, Zurich, Switzerland.B.G. Weiss, MD, Department of Physical Medicine and Rheumatology, Balgrist University Hospital; L.M. Bachmann, MD, PhD, Professor, Medignition Inc. Research Consultants; C.W. Pfirrmann, MD, exec. MBA UZH, Department of Radiology, Balgrist University Hospital; R.O. Kissling, MD, Professor, Department of Physical Medicine and Rheumatology, Balgrist University Hospital; V. Zubler, MD, Department of Radiology, Balgrist University Hospital. bettina.weiss@balgrist.ch. 2. From the Department of Physical Medicine and Rheumatology, and Department of Radiology, Balgrist University Hospital; Medignition Inc. Research Consultants, Zurich, Switzerland.B.G. Weiss, MD, Department of Physical Medicine and Rheumatology, Balgrist University Hospital; L.M. Bachmann, MD, PhD, Professor, Medignition Inc. Research Consultants; C.W. Pfirrmann, MD, exec. MBA UZH, Department of Radiology, Balgrist University Hospital; R.O. Kissling, MD, Professor, Department of Physical Medicine and Rheumatology, Balgrist University Hospital; V. Zubler, MD, Department of Radiology, Balgrist University Hospital.
Abstract
OBJECTIVE: Discrimination of diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) can be challenging. Usefulness of whole-body magnetic resonance imaging (WB-MRI) in diagnosing spondyloarthritis has been recently proved. We assessed the value of clinical variables alone and in combination with WB-MRI to distinguish between DISH and AS. METHODS: Diagnostic case-control study: 33 patients with AS and 15 patients with DISH were included. All patients underwent 1.5 Tesla WB-MRI scanning. MR scans were read by a blinded radiologist using the Canadian-Danish Working Group's recommendation. Imaging and clinical variables were identified using the bootstrap. The most important variables from MR and clinical history were assessed in a multivariate fashion resulting in 3 diagnostic models (MRI, clinical, and combined). The discriminative capacity was quantified using the area under the receiver-operating characteristic (ROC) curve. The strength of diagnostic variables was quantified with OR. RESULTS: Forty-eight patients provided 1545 positive findings (193 DISH/1352 AS). The final MR model contained upper anterior corner fat infiltration (32 DISH/181 AS), ankylosis on the vertebral endplate (4 DISH/60 AS), facet joint ankylosis (4 DISH/49 AS), sacroiliac joint edema (11 DISH/91 AS), sacroiliac joint fat infiltration (2 DISH/114 AS), sacroiliac joint ankylosis (2 DISH/119 AS); area under the ROC curve was 0.71, 95% CI 0.64-0.78. The final clinical model contained patient's age and body mass index (area under the ROC curve 0.90, 95% CI 0.89-0.91). The full diagnostic model containing clinical and MR information had an area under the ROC curve of 0.93 (95% CI 0.92-0.95). CONCLUSION: WB-MRI features can contribute to the correct diagnosis after a thorough conventional workup of patients with DISH and AS.
OBJECTIVE: Discrimination of diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) can be challenging. Usefulness of whole-body magnetic resonance imaging (WB-MRI) in diagnosing spondyloarthritis has been recently proved. We assessed the value of clinical variables alone and in combination with WB-MRI to distinguish between DISH and AS. METHODS: Diagnostic case-control study: 33 patients with AS and 15 patients with DISH were included. All patients underwent 1.5 Tesla WB-MRI scanning. MR scans were read by a blinded radiologist using the Canadian-Danish Working Group's recommendation. Imaging and clinical variables were identified using the bootstrap. The most important variables from MR and clinical history were assessed in a multivariate fashion resulting in 3 diagnostic models (MRI, clinical, and combined). The discriminative capacity was quantified using the area under the receiver-operating characteristic (ROC) curve. The strength of diagnostic variables was quantified with OR. RESULTS: Forty-eight patients provided 1545 positive findings (193 DISH/1352 AS). The final MR model contained upper anterior corner fat infiltration (32 DISH/181 AS), ankylosis on the vertebral endplate (4 DISH/60 AS), facet joint ankylosis (4 DISH/49 AS), sacroiliac joint edema (11 DISH/91 AS), sacroiliac joint fat infiltration (2 DISH/114 AS), sacroiliac joint ankylosis (2 DISH/119 AS); area under the ROC curve was 0.71, 95% CI 0.64-0.78. The final clinical model contained patient's age and body mass index (area under the ROC curve 0.90, 95% CI 0.89-0.91). The full diagnostic model containing clinical and MR information had an area under the ROC curve of 0.93 (95% CI 0.92-0.95). CONCLUSION: WB-MRI features can contribute to the correct diagnosis after a thorough conventional workup of patients with DISH and AS.