Objective:To evaluate the performance of magnetic resonance imaging (MRI) in detecting
periosteal reactions and to compare MRI and conventional radiography (CR) in
terms of the classification of periosteal reactions.Materials and Methods:Retrospective study of 42 consecutive patients (mean age, 22 years; 20 men)
with a confirmed diagnosis of osteosarcoma or Ewing's sarcoma, MRI and CR
images having been acquired pretreatment. Three blinded radiologists
detected periosteal reactions and evaluated each periosteal reaction subtype
in CR and MRI images: Codman's triangle; laminated; and spiculated. The CR
was used as a benchmark to calculate the diagnostic performance. We used the
kappa coefficient to assess interobserver reproducibility. A two-tailed
Fisher's exact test was used in order to assess contingency between CR and
MRI classifications.Results:In the detection of periosteal reactions, MRI showed high specificity, a high
negative predictive value, and low-to-moderate sensitivity. For CR and for
MRI, the interobserver agreement for periosteal reaction was almost perfect,
whereas, for the classification of different subtypes of periosteal
reaction, it was higher for the Codman's triangle subtype and lower for the
spiculated subtype. There was no significant difference between MRI and CR
in terms of the classifications (p < 0.05).Conclusion:We found no difference between MRI and CR in terms of their ability to
classify periosteal reactions. MRI showed high specificity and almost
perfect interobserver agreement for the detection of periosteal reactions.
The interobserver agreement was variable for the different subtypes of
periosteal reaction.