Relationship between the clinical characteristics of osteomyelitis and

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May 7, 2011 - Abstract. Background MRI is frequently utilized to evaluate patients for osteomyelitis. The findings of intramedullary and extramedullary fat ...
Pediatr Radiol (2011) 41:1293–1297 DOI 10.1007/s00247-011-2073-8

ORIGINAL ARTICLE

Relationship between the clinical characteristics of osteomyelitis and the finding of extraosseous fat on MRI in pediatric patients Tod A. Mattis & Heather L. Borders & Doug M. Ellinger & Joseph J. Junewick

Received: 13 December 2010 / Revised: 28 February 2011 / Accepted: 14 March 2011 / Published online: 7 May 2011 # Springer-Verlag 2011

Abstract Background MRI is frequently utilized to evaluate patients for osteomyelitis. The findings of intramedullary and extramedullary fat globules as well as extramedullary fatfluid levels can help improve the specificity of MRI for this diagnosis. Objective To correlate these MRI findings with the clinical characteristics in children with osteomyelitis. Materials and methods A retrospective electronic medical record search for pediatric patient charts from March 2004 to November 2009 that contained the word “osteomyelitis” in the “principal diagnosis” portion of the international classification of disease (ICD) billing code. Each electronic chart was reviewed. MRI examinations of selected children were reviewed by a pediatric radiologist, a general radiologist and a transitional year resident. Results A total of 10 patients/11 MRI studies were included. Five of the 11 had the MRI finding of extramedullary globular fat signal. There was a significantly increased likelihood of T. A. Mattis : H. L. Borders (*) : D. M. Ellinger : J. J. Junewick Spectrum Health Helen Devos Children’s Hospital, 100 Michigan St. NE, Grand Rapids, MI 49503, USA e-mail: [email protected] T. A. Mattis : H. L. Borders : D. M. Ellinger : J. J. Junewick College of Human Medicine, Radiology, Michigan State University, Grand Rapids, MI, USA T. A. Mattis Grand Rapids Medical Education Partners, Grand Rapids, MI, USA H. L. Borders : D. M. Ellinger : J. J. Junewick Advanced Radiology Services, Grand Rapids, MI, USA

seeing this finding in children of pubertal or postpubertal age compared to those of prepubertal age (p9.9 nmol/L was considered elevated

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Table 2 MRI characteristics Fat globules presenta

Fat globules not present

P-value for Fisher exact test

Presence of abscess (% yes) Location of abscess (% subperiosteal) Presence of hemorrhage Location of hemorrhage (% subperiosteal) Subperiosteal fluid collection Location (upper extremity:lower extremity) Fat-fluid level presence Medullary enhancement

3/5 2/3 2/5 0/2 5/5 2:3 0/5 5/5

3/6 3/3 1/6 1/1 4/6 1:5 0/6 6/6

(0%) (100%)

1.00 1.00 0.55 0.33 0.45 0.55 NA NA

Periosteal enhancement

4/5 (80%)

6/6 (100%)

0.45

(60%) (66.7%) (40%) (0%) (100%) (0%) (100%)

(50%) (100%) (16.7%) (100%) (66.7%)

a One patient had two infected bones at the same time and both bones had fat globules present. Each bone is counted separately for the purposes of this analysis.

correlation between T1 and either fat-suppressed imaging or CT. Groups were divided based upon the presence or absence of fat globules. Comparisons for nominal variables were compared using the Fisher exact test, while comparisons for nominal variables were made using the Mann-Whitney test. Significance was assessed at p