title: Comparison of sequences for depicting bone marrow alterations in osteomyelitis applied in a low field strength magnetic resonance imaging system.
abstract: OBJECTIVE
  To investigate the efficacy of standard sequences of a low field system for the detection of osteomyelitis, we tested T1wI pre and post i.v. contrast, T2w and fat suppressed IR sequences.
  
  
  METHODS
  On the basis of clinical and laboratory evidence, pathology reports, and three phase granulocyte scintigraphy, osteomyelitis was diagnosed in 18 of 21 patients with Charcot's joints. A consecutive low and high field magnetic resonance (MR) scan confirmed osteomyelitic bone marrow changes in the same osseous regions. These 18 diabetic patients were then studied on a 0.2 Tesla dedicated MR system (Esaote ArtoScan) using T1wI (SE: relaxation time (TR) 520/echo time (TE) 24: axial and coronal) before and after i.v. application of 0.1 mmol/l Gd-DTPA/kg BW, T2w imaging (TSE: TR 3500/TE 80 or TR 2000/TE 120: axial), and fat suppressed inversion recovery (IR) imaging (short tau inversion recovery (STIR): TR 3000/TE 30/TI 80 or inversion recovery gradient echo (IRGE)/fat suppressed IRGE (GEFS): TR 1000/TE 16m 80: coronal).
  
  
  RESULTS
  The SE T1w sequence showed a significantly higher contrast-to-noise ratio (CNR) before administration of i.v. contrast. The TSE T2w pulse sequence demonstrated bone marrow changes superiorily utilizing a TE of 120 ms (CNR = 16.5+/-2.7 compared to 5.5+/-2.5 with TE = 80 ms). The IRGE showed a higher CNR than the standard STIR (CNR = 19.2+/-2.5 compared to 12.4+/-2.9).
  
  
  CONCLUSIONS
  Fat suppressed IRGE imaging and longer TE in T2w TSE sequences result in a significantly better CNR in osteomyelitis. This way, using optimized sequences, low field systems are apt to depict bone marrow changes in the course of osteomyelitis.
authors.affiliation: Institut for Radiological Diagnosis, Klinikum Grosshadern der Ludwigs-Maximilians-Universität, Munich, Germany. hbonel@compuserve.com
authors.forename: H
authors.initials: H
authors.lastname: Bonél
authors.forename: T
authors.initials: T
authors.lastname: Helmberger
authors.forename: H C
authors.initials: HC
authors.lastname: Geiss
authors.forename: M
authors.initials: M
authors.lastname: Steinborn
authors.forename: M M
authors.initials: MM
authors.lastname: Ritter
authors.forename: M
authors.initials: M
authors.lastname: Reiser
mesh_terms: D000293:Adolescent; D000328:Adult; D001853:Bone Marrow / Q000473:pathology*; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010019:Osteomyelitis / Q000175:diagnosis* / Q000473:pathology*; D010865:Pilot Projects