title: Biochemical cartilage alteration and unexpected signal recovery in T2* mapping observed in ankle joints with mobile MRI during a transcontinental multistage footrace over 4486 km.
abstract: OBJECTIVE
  The effect of ultra-long distance running on the ankle cartilage with regard to biochemical changes, thickness and lesions is examined in the progress of a transcontinental ultramarathon over 4486 km.
  
  
  METHODS
  In an observational field study, repeated follow-up scanning of 22 participants of the TransEurope FootRace (TEFR) with a 1.5 T MRI mounted on a mobile unit was performed. For quantitative biochemical and structural evaluation of cartilage a fast low angle shot (FLASH) T2* weighted gradient-echo (GRE)-, a turbo-inversion-recovery-magnitude (TIRM)- and a fat-saturated proton density (PD)-weighted sequence were utilized. Statistical analysis of cartilage T2* and thickness changes was obtained on the 13 finishers (12 male, mean age 45.4 years, BMI 23.5 kg/m²). None of the nine non-finisher (eight male, mean age 53.8 years, BMI 23.4 kg/m²) stopped the race due to ankle problems.
  
  
  RESULTS
  From a mean of 17.0 ms for tibial plafond and 18.0 ms for talar dome articular cartilage at baseline, nearly all observed regions of interest (ROIs) of the ankle joint cartilage showed a significant T2*-signal increase (25.6% in mean), with standard error ranging from 19% to 33% within the first 2500 km of the ultra-marathon. This initial signal behavior was followed by a signal decrease. This signal recovery (30.6% of initial increase) showed a large effect size. No significant morphological or cartilage thickness changes (at baseline 2.9 mm) were observed.
  
  
  CONCLUSIONS
  After initial T2*-increase during the first 2000-2500 km, a subsequent T2*-decrease indicates the ability of the normal cartilage matrix to partially regenerate under ongoing multistage ultramarathon burden in the ankle joints.
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, Ulm D-89081, Germany. Electronic address: uwe.schuetz@rocketmail.com.
authors.forename: U H W
authors.initials: UH
authors.lastname: Schütz
authors.affiliation: Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, USA. Electronic address: eller001@umn.edu.
authors.forename: J
authors.initials: J
authors.lastname: Ellermann
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, Ulm D-89081, Germany. Electronic address: daniel.schoss@gmx.de.
authors.forename: D
authors.initials: D
authors.lastname: Schoss
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, Ulm D-89081, Germany. Electronic address: heike.wiedelbach@uniklinik-ulm.de.
authors.forename: H
authors.initials: H
authors.lastname: Wiedelbach
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, Ulm D-89081, Germany. Electronic address: meinrad.beer@uniklinik-ulm.de.
authors.forename: M
authors.initials: M
authors.lastname: Beer
authors.affiliation: Department of Diagnostic and Interventional Radiology, University Hospital Ulm, Albert-Einstein-Allee 23, Ulm D-89081, Germany. Electronic address: christian.billich@uniklinik-ulm.de.
authors.forename: C
authors.initials: C
authors.lastname: Billich
mesh_terms: D000843:Ankle Joint / Q000502:physiology*; D001669:Biochemical Phenomena; D002358:Cartilage, Articular / Q000033:anatomy & histology / Q000737:chemistry*; D005260:Female; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012420:Running / Q000502:physiology*
chemical_list: D006025:Glycosaminoglycans
keywords: Ankle; Cartilage; Glycosaminoglycan; Marathon; Proteoglycan; Running