[Bone inflammation (including spondylitis)]

MRI diagnosis of bony inflammations has sensitivity of up to 96%, but specificity of only 70-87%. The most common reasons for false-positive results are fractures, infarctions, neoplasms, septic arthritis and aggressive metastasis. Early MRI diagnosis is based on bone marrow oedema, which is hypointense on T1-weighted images, hyperintense on T2-weighted images. Reactive fibrovascular tissue and hyperaemia lead to contrast enhancement. Necrosis, calcification and sequestra show low signal intensities. Increasing calcifications and restructuring of spongiosa are not well visualized in MRI. In spondylitis, fat conversion is a good marker for healing. Complications of osteomyelitis (e.g. soft tissue abscesses) can be diagnosed by MRI with high sensitivity. In the primary diagnosis and follow-up of osteomyelitis (spondylitis), standard X-ray exams should be performed first. In the initial studies MRI can replace bone scintigraphy, which has poor morphological resolution. Semiquantitative follow-up studies can be done by MRI or scintigraphy.