Diagnostic accuracy of MR imaging for direct visualization of lumbar pars defect in children and young adults: a systematic review and meta-analysis

The accurate diagnosis of spondylolysis is widely made with CT scan considered as the gold standard. However, CT represents significant radiation exposure particularly substantial in a young and sometimes still growing population. Although the role of MRI in identifying edema/inflammation within the pars as an active lesion is proved, its ability to demonstrate and classify pars fracture line as same as CT is still controversial. This meta-analysis aimed to determine sensitivity and specificity of MRI in the direct visualisation of the pars defect. The PubMed and Embase databases were systematically searched for relevant studies from the earliest researchable time to December 2016 for cases in which the accuracy of MRI was reported for the diagnosis of spondylolysis in young patients. Two reviewers independently assessed the methodological quality for each selected study using the quality assessment of diagnostic accuracy studies 2 tool. A meta-analysis of the reported sensitivity and specificity of pooled data of selected studies was performed by a systematic review. For each selected study, sensitivity and specificity was recalculated, by considering only direct visualisation of a fracture line of the pars. The hierarchic summary receiver operating characteristic curve was generated to estimate the diagnostic performance of MR imaging. Heterogeneity was also tested. The systematic review identified 4 out of a total of 1300 studies to be included in the meta-analysis. On a per-pars basis (a total of 1122 pars), the pooled sensitivity and specificity of the MRI for the direct diagnosis of a pars defect were 81% (95% CI 54–94%) and 99% (95% CI 98–100%), respectively. A high overall heterogeneity (I2 = 79.5%) was computed with respective high and low heterogeneity on sensitivity (I2 = 87.9%) and specificity (I2 = 38.4%). This meta-analysis demonstrated a high diagnostic performance of MR imaging for the diagnosis of a pars defect in young adults. This technique may be considered as a first-line imaging technique as it helps to avoid exposure to ionising radiation.