Computed tomography versus magnetic resonance imaging for the perioperative management of acute thoracolumbar intervertebral disc extrusion in non‐ambulatory chondrodystrophic dogs
Daniel Low, Andrea MarkovicAbstract
Objective
To determine whether perioperative management guided by conditional computed tomography‐myelography (C‐CTM) is non‐inferior to magnetic resonance imaging (MRI) regarding functional outcome for acute thoracolumbar intervertebral disc extrusion (IVDE) in non‐ambulatory chondrodystrophic dogs.
Study design
Quasi‐randomized natural experiment utilizing unscheduled MRI downtime as an exogenous instrument.
Sample population
A total of 560 client‐owned dogs (MRI, 518 dogs; C‐CTM, 42 dogs).
Methods
A retrospective cohort study was conducted. The primary outcome was recovery of ambulation, analyzed with intention‐to‐treat (ITT) and per‐protocol (PP) principles with a prespecified non‐inferiority margin of −12%. Secondary outcomes included safety events (postoperative neurologic deterioration, progressive myelomalacia, major complications) and time‐adjusted treatment costs.
Results
C‐CTM was non‐inferior to MRI for recovery of ambulation in both ITT (risk difference + 6.5%, 95% CI: −2.7%–15.7%, one‐sided p < .001) and PP analyses (risk difference + 2.5%, 95% CI: −7.3%–12.2%, one‐sided p < .001). There was no difference in rates of postoperative neurologic deterioration, progressive myelomalacia, or major complications. Total treatment costs and imaging costs were significantly lower for C‐CTM ( p < .01). There was no difference in non‐imaging costs between groups.
Conclusion
In non‐ambulatory chondrodystrophic dogs with acute thoracolumbar IVDE, C‐CTM is non‐inferior to MRI for recovery of ambulation with a similar safety profile, at significantly lower cost.
Clinical significance
In dogs with a high pretest probability of acute thoracolumbar IVDE, routine use of MRI may not be justified given the comparable clinical outcomes and lower treatment costs achieved with C‐CTM.