Abstract: Objective To analyze the clinical diagnostic effect of multi-slice spiral CT combined with magnetic resonance imaging （MRI） for occult fractures of the lower extremities. Methods A retrospective analysis was conducted on 64 patients with suspected occult fractures of the lower extremities admitted to our hospital from April 2021 to March 2026. All patients underwent multi-slice spiral CT and MRI examinations. The surgical exploration results were used as the gold standard to compare the diagnostic efficacy of the two imaging examinations alone and in combination, as well as their detection rates for different fracture details. Results The sensitivity, negative predictive value, and accuracy of MRI were higher than those of multi-slice spiral CT （P<0.05）. The sensitivity, negative predictive value, and accuracy of combined diagnosis were higher than those of either examination alone （P<0.05）. MRI had higher detection rates for cortical discontinuity, trabecular damage, collapse of the knee articular surface, and abnormal joint space width compared to multi-slice spiral CT （P<0.05）, and the combination of the two further improved the detection rates （P<0.05）. Conclusion Both multi-slice spiral CT and MRI have diagnostic value for occult fractures of the lower extremities, and their combination can enhance diagnostic efficacy and provide more accurate information for clinical diagnosis.

Key words: Multi-slice spiral CT, Magnetic resonance imaging, Occult fracture of lower extremity, Diagnosis, Accuracy