Introduction:
CT scan has been commonly used to determine the stage of fracture progression when assessing and treating lumbar spondylolysis. However, compared to adults, pediatric patients have increased organ radiosensitivity and longer life expectancy, so their longitudinal radiation exposure should be limited. Recently, we have started using bone like image (BLI) of MRI instead of plain CT scan to limit radiation exposure. The aim of this study was to validate the BLI of each stage of lumbar spondylolysis disease progression compared with CT scans.
Methods:
We retrospectively investigated BLIs and CT scans of 114 patients (95 males and 19 females, mean 14.2 ± 1.7 years) with lumbar spondylolysis taken from November 2021 to March 2023. A total of 1050 pars interarticularis were examined. All compared MRI and CT images were obtained within 1 month. The BLI used in this study was based on a Siemens 3 Tesla volumetric interpolated breath-hold imaging (VIBE). The CT-based staging (early, progressive, terminal) was matched with the BLI-based staging (incomplete fracture line, complete fracture line, and gap of 2 mm or more) due to its characteristics, respectively.
Results:
Of the 133 “early-stage fracture”, 127 were interpreted as “incomplete fracture” on BLI (concordance rate: 95.5%). Of the 52 “progressive-stage fracture”, 38 were interpreted as “complete fracture” (concordance rate: 73.0%). And, of the 18 “terminal-stage fracture”, 15 were interpreted as “gap” (concordance rate: 83.3%.)
Sensitivity, specificity, and accuracy of the BLI in diagnosing fractures compared with CT scans were 95.5, 99.2, and 98.8% in early stage; 73.0, 99.5, 98.1% in progressive stage; 83.3, 99.2, 99.0% in terminal stage; and 88.7, 97.2, 95.5 for all fractures.
Of the 134 cases with “incomplete fracture” on BLI, 127 were interpreted as “early-stage fracture” on CT (concordance rate: 94.8%.) Of the 43 “complete fracture”, 38 were interpreted as “progressive-stage fracture” (concordance rate: 88.4%.) And, of the 23 “gap”, 15 were interpreted as “terminal-stage fracture” (concordance rate: 65.2%.)
Of the 66 cases with “complete fracture” or “gap”, 64 cases were applicable to “progressive-stage fracture” or “terminal-stage fracture” (concordance rate: 97.0%.)
Discussion:
The concordance rates of “progressive-stage fracture” and “terminal-stage fracture” were lower than that of “progressive-stage fracture”. However, when “progressive-stage fracture” and “terminal-stage fracture” were evaluated together, the concordance rate was higher than when evaluated individually. With this finding, BLI is considered to be sufficient for use in clinical practice.
In the future, this imaging technology may become indispensable for reducing radiation exposure in the medical treatment for pediatric patients with spinal diseases.