title: Quantification of Bone Marrow Involvement in Treated Gaucher Disease With Proton MR Spectroscopy: Correlation With Bone Marrow MRI Scores and Clinical Status.
abstract: OBJECTIVE
  The objective of our study was to use proton MR spectroscopy (MRS) to quantitatively evaluate bone marrow infiltration by measuring the fat fraction (FF) and to compare the FF with semiquantitative bone marrow MRI scores and clinical status in children treated for type 1 Gaucher disease (GD).
  
  
  METHODS
  Over a 2-year period, we prospectively evaluated 10 treated GD patients (six males, four females; median age, 15.1 years) and 10 healthy age-matched control subjects (five males, five females; median age, 15.3 years) using 3-T proton MRS of L5 and the femoral neck. Water and lipid AUCs were measured to calculate the FF. Two blinded pediatric musculoskeletal radiologists performed a semiquantitative analysis of the conventional MR images using the bone marrow burden score and modified Spanish MRI score. We evaluated symptoms, spleen and liver volumes, platelet levels, hemoglobin levels, and bone complications.
  
  
  RESULTS
  In the femur, the FF was higher in the control subjects (median, 0.71) than the GD patients (0.54) (p = 0.02). In L5, the difference in FF--higher FF in control subjects (0.37) than in GD patients (0.26)--was not significant (p = 0.16). In both groups and both regions, the FF increased with patient age (p < 0.02). Semiquantitative scores showed no differences between control subjects and treated GD patients (p > 0.11). Eight of 10 GD patients were asymptomatic and two had chronic bone pain. The median age of patients at symptom onset was 4.0 years, the median age of patients at the initiation of enzyme replacement therapy was 4.3 years, and the median treatment duration was 10.2 years. Hemoglobin level, platelet count, and liver volume at MRI were normal. Mean pretreatment spleen volume (15.4-fold above normal) decreased to 2.8-fold above normal at the time of MRI (p = 0.01).
  
  
  CONCLUSIONS
  Proton MRS detected FF differences that were undetectable using conventional MRI; for that reason, proton MRS can be used to optimize treatment of GD patients.
authors.affiliation: 1 Department of Radiology, The Children's Hospital of Philadelphia, 34th St and Civic Center Blvd, Philadelphia, PA 19104.
authors.forename: Diego
authors.initials: D
authors.lastname: Jaramillo
authors.forename: Maria A
authors.initials: MA
authors.lastname: Bedoya
authors.forename: Dah-Jyuu
authors.initials: DJ
authors.lastname: Wang
authors.forename: Andres H
authors.initials: AH
authors.lastname: Pena
authors.forename: Jorge
authors.initials: J
authors.lastname: Delgado
authors.forename: Camilo
authors.initials: C
authors.lastname: Jaimes
authors.forename: Victor
authors.initials: V
authors.lastname: Ho-Fung
authors.forename: Paige
authors.initials: P
authors.lastname: Kaplan
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism* / Q000473:pathology; D000293:Adolescent; D000328:Adult; D001853:Bone Marrow / Q000378:metabolism* / Q000473:pathology; D001855:Bone Marrow Diseases / Q000175:diagnosis* / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005776:Gaucher Disease / Q000175:diagnosis* / Q000378:metabolism* / Q000628:therapy; D006801:Humans; D008297:Male; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
keywords: Gaucher disease; MR spectroscopy; MRI; bone marrow