title: Magnetic Resonance Imaging Features as Surrogate Markers of X-Linked Hypophosphatemic Rickets Activity.
abstract: OBJECTIVE
  X-linked hypophosphatemic rickets (XLH) is the most common form of inheritable rickets. Rickets treatment is monitored by assessing alkaline phosphatase (ALP) levels, clinical features, and radiographs. Our objectives were to describe the magnetic resonance imaging (MRI) features of XLH and to assess correlations with disease activity.
  
  
  METHODS
  Twenty-seven XLH patients (median age 9.2 years) were included in this prospective single-center observational study. XLH activity was assessed using height, leg bowing, dental abscess history, and serum ALP levels. We looked for correlations between MRI features and markers of disease activity.
  
  
  RESULTS
  On MRI, the median maximum width of the physis was 5.6 mm (range 4.8-7.8; normal <1.5), being >1.5 mm in all of the patients. The appearance of the zone of provisional calcification was abnormal on 21 MRI images (78%), Harris lines were present on 24 (89%), and bone marrow signal abnormalities were present on 16 (59%). ALP levels correlated with the maximum physeal widening and with the transverse extent of the widening.
  
  
  CONCLUSIONS
  MRI of the knee provides precise rickets patterns that are correlated with ALP, an established biochemical marker of the disease, avoiding X-ray exposure and providing surrogate quantitative markers of disease activity.
authors.affiliation: AP-HP, Bicêtre Paris-Sud Hospital, Department of Pediatric Radiology, Le Kremlin-Bicêtre, France.
authors.forename: Marta
authors.initials: M
authors.lastname: Lempicki
authors.affiliation: AP-HP, Bicêtre Paris-Sud Hospital, Department of Pediatric Endocrinology, Diabetology and Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Filière OSCAR and Platform of Expertise Paris-Sud for Rare Diseases, Le Kremlin-Bicêtre, France.
authors.forename: Anya
authors.initials: A
authors.lastname: Rothenbuhler
authors.affiliation: AP-HP, Bicêtre Paris-Sud Hospital, Department of Pediatric Radiology, Le Kremlin-Bicêtre, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Merzoug
authors.affiliation: AP-HP, Bicêtre Paris-Sud Hospital, Department of Pediatric Radiology, Le Kremlin-Bicêtre, France.|LTCI Telecom Paris Tech, Paris Saclay University, Le Kremlin-Bicêtre, France.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Franchi-Abella
authors.affiliation: AP-HP, Bretonneau Hospital, Odontology Department, Paris, France.|Paris Descartes University, EA2496, Montrouge, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Chaussain
authors.affiliation: AP-HP, Bicêtre Paris-Sud Hospital, Department of Pediatric Radiology, Le Kremlin-Bicêtre, France.|Paris-Sud University, Medical School, Le Kremlin-Bicêtre, France.|LTCI Telecom Paris Tech, Paris Saclay University, Le Kremlin-Bicêtre, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Adamsbaum
authors.affiliation: AP-HP, Bicêtre Paris-Sud Hospital, Department of Pediatric Endocrinology, Diabetology and Reference Center for Rare Disorders of Calcium and Phosphate Metabolism, Filière OSCAR and Platform of Expertise Paris-Sud for Rare Diseases, Le Kremlin-Bicêtre, France.|Paris-Sud University, Medical School, Le Kremlin-Bicêtre, France.|Inserm U1169, Bicêtre Paris-Sud Hospital and Paris-Saclay University, Le Kremlin-Bicêtre, France.
authors.forename: Agnès
authors.initials: A
authors.lastname: Linglart
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism*; D015415:Biomarkers / Q000097:blood; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000378:metabolism; D002648:Child; D053098:Familial Hypophosphatemic Rickets / Q000097:blood / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008297:Male
chemical_list: D015415:Biomarkers; D000469:Alkaline Phosphatase
keywords: Magnetic resonance imaging; Physis; Rickets; X-linked hypophosphatemic rickets; Zone of provisional calcification