Benedikt Michael Schaarschmidt MD, Presenter: Nothing to Disclose

Xenofon Baraliakos MD, Abstract Co-Author: Nothing to Disclose

Karsten J. Beiderwellen MD, Abstract Co-Author: Nothing to Disclose

Verena Ruhlmann, Abstract Co-Author: Nothing to Disclose

Gerald Antoch MD, Abstract Co-Author: Speaker, Siemens Medical AG Speaker, Bayer AG Speaker, BTG International Ltd

Christian Buchbender, Abstract Co-Author: Nothing to Disclose

Treatment of active ankylosing spondylitis (AS) has undergone a dramatic change with the introduction of new, innovative biologicals like TNFα-blockers. To monitor treatment, more advanced imaging techniques are warranted. Integrated PET/MRI-Scanners may improve diagnostics by combining the high sensitivity of MRI for fat depositions (FD) and bone marrow edema (BME) with the option to monitor osteoblastic activity at a molecular level. The aim of this study was to correlate inflammatory and structural changes depicted by MRI with osteoblastic activity depicted by 18F-Fluoride PET.

Simultaneous PET/MRI (Magnetom Biograph mMR™, Siemens) was performed in 13 patients with AS in the mineralization phase 40 min after the injection of 18F-Fluoride (mean injected dose 157MBq). 18F-Fluoride uptake, sacroiliacal joint (SIJ) sclerosis, ankylosis and erosions as well as BME and FD were reviewed by two independent readers and recorded according to their location in the sacroiliac joint quadrant (SQ) or vertebral quadrant (VQ).

In the spine, FD were observed in 18.2%, BME in 9.9% and fluoride-avid lesions in 5.4% of VQ. Most frequently, high fluoride uptake in the spine was associated with FD (63.1% of VQ), followed by BME (53.8% of VQ). In the SIJ, fluoride-avid lesions were observed in 46.2%, BME in 44.2%, FD in 42.3% and erosions in 32.7% of SQ, while sclerosis and ankylosis was only seen in 19.2% and 9.6% of SQ, respectively. Most frequently, a high fluoride uptake in the SIJ was associated with BME (72.9% of SQ) and erosions (43.8%).

In the SIJ and the spine, high osteoblastic activity was observed in correlation with acute inflammatory as well as post-inflammatory MRI changes revealing that a fraction of chronic lesions in AS is metabolically active. Thus, 18F-Fluorid PET/MRI may be able to identify lesions at risk for development of syndesmophytes.

This study helps to understand and potentially predict structural changes in AS patients and provides important information for further trials concerning treatment response in AS.  

Schaarschmidt, B, Baraliakos, X, Beiderwellen, K, Ruhlmann, V, Antoch, G, Buchbender, C, Simultaneous [18]F-Fluoride PET/MRI in Patients with Axial Spondyloarthritis: A Feasibility Study and Comparison of Lesions in the Sacroiliacal Joints and the Spine.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007126.html