Can MRI Replace CT in the Diagnosis and Staging of Lumbar Spondylolysis in Pediatric Patients? A Validation Study Using MR Bone Imaging.

BACKGROUND

Magnetic resonance (MR) bone imaging may reduce radiation exposure compared with computed tomography (CT) in staging lumbar spondylolysis. This study aimed to validate the consistency between MR bone imaging and CT.

METHODS

We retrospectively investigated short tau inversion recovery (STIR), MR bone imaging, and CT scans of patients diagnosed with lumbar spondylolysis who underwent MRI and CT scans within 2 weeks between November 2021 and March 2023.We identified 190 fractures in 968 pars interarticularis of 105 patients. MR bone imaging was based on Siemens 3 Tesla T1-weighted volumetric interpolated breath-hold imaging (T1 VIBE). The CT-based staging and T1 VIBE-based staging were matched [incomplete fracture, complete fracture, gap of ≥2 mm (gap)].

RESULTS

For fracture detection with CT as a reference, the respective sensitivity, specificity, and accuracy were 94%, 99%, and 99% for incomplete fracture, 74%, 100%, and 98% for complete fracture, 81%, 99%, and 99% for gap, and 97%, 100%, and 100% for any fracture. When we assessed 62 pars with complete fracture or a gap, the rates were 91%, 100%, and 99%, respectively. In staging 190 fractures with CT as a reference, the respective sensitivity, specificity, and accuracy were 94%, 91%, and 93% for incomplete fracture, 74%, 96%, and 91% for complete fracture, 81%, 96%, and 95% for gap, and 97%, 100%, and 97% for any fracture. The respective values were 91%, 98%, and 96% for complete fracture combined with gap. Of 153 pedicles with high signal change on STIR, 10 showed no fracture line, 110 showed incomplete fracture lines, 30 showed complete fracture lines, and 3 showed a gap on T1 VIBE, compared with 5, 109, 39, and 0, respectively, on CT.

CONCLUSIONS

The T1 VIBE sequence is highly accurate, although it has some limitations in fracture detection. T1 VIBE can be used clinically in conjunction with STIR and may replace CT in determining the treatment strategy for lumbar spondylolysis, resulting in reduced medical radiation exposure to pediatric patients.

LEVEL OF EVIDENCE: Level III diagnostic study.