MRT-Diagnostik bei axialer Spondyloarthritis

Zusammenfassung

Die Diagnose einer axialen Spondyloarthritis (axSpA) umfasst die klassische ankylosierende Spondylitis (AS), aber auch potenziell frü-here Phasen und abortive Verläufe der Erkrankung, welche als nichtröntgenologische axSpA (nr-axSpA) klassifiziert werden. Charakteristisch für die axSpA sind entzündliche Veränderungen im gesamten Achsenskelett (Sakroiliakalgelenke und Wirbelsäule), später kommen bei vielen Patienten auch strukturelle Veränderungen wie die charakteristische Knochenneubildung mit Syndesmophyten und Ankylosierungen hinzu. Während knöcherne Veränderungen bei axSpA am besten durch konventionelle Röntgentechniken und zum Teil durch Computertomografie darstellbar sind, ist die Magnetresonanztomografie (MRT) heute die Standardmethode zur Erfas-sung entzündlicher Veränderungen. Die Einführung der MRT hat inzwischen zu einem diagnostischen Paradigmenwechsel geführt, weil mit den geeigneten Sequenzen die für die Erkrankung charakteristischen entzündlichen Läsionen frühzeitig abgebildet werden können. So nimmt die Bildgebung der Sakro -iliakalgelenke (SIG) mittels MRT bei den neuen ASAS-Klassifikationskriterien für axSpA einen zentralen Platz ein. Bei der bereits vor einigen Jahren publizierten ASAS-Definition einer positiven MRT der SIGs spielt der Nachweis eines Knochenmarködems eine wichtige Rolle. Der genaue Zusammenhang zwischen Entzündung und Osteoproliferation ist noch nicht vollständig geklärt, allerdings haben sowohl die entzündlichen als auch die postentzündlichen Veränderungen – in der MRT als Verfettung zu erkennen – als Vorstufe zur Knochenneu -bildung eine essenzielle Bedeutung.

Summary

The diagnosis of axial spondyloarthritis (axSpA) includes the classical ankylosing spondylitis (AS) but also potentially earlier stages and abortive courses of the disease, which can be classified as non-radiographic axSpA (nr-axSpa). Inflammatory changes in the entire axial skeleton (sacroiliac joints [SIJ] and spine) are characteristic for axSpA, while structural changes like new bone formation with syndesmophytes and ankylosis can develop in the later course of the disease. While bony changes can be best visualized by conventional radiographs but also by computer tomography, magnetic resonance imaging (MRI) is nowadays considered as the standard method for depiction of inflammatory changes in axSpA. The introduction of MRI has lead, in the meanwhile, to a paradigm shift in this disease, since the characteristic inflammatory lesions can be visualized early enough by using appropriate MRI sequences. This has led to the MRI of the sacroiliac joints (SIJ) to be a central feature of the new ASAS classification criteria for axSpA. In the ASAS definition of a positive MRI, evidence of bone marrow edema in the MRI of the SIJ plays an important role. The issue of a direct relationship between inflammation and osteoproliferation has not been entirely solved, although both inflammatory and also post-inflammatory changes, such as fatty degeneration as depicted by MRI, are considered to play an essential role in the process of new bone formation in axSpA.

Schlüsselwörter

Axiale Spondyloarthritis - ankylosierende Spondylitis - nichtröntgenologische axiale Spondyloarthritis - MRT - Klassifikationskriterien

Keywords

Axial spondyloarthritis - ankylosing spondylitis - non-radiographic axial spondyloarthritis - MRI - classification criteria

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