Distribution of Contrast Medium Epidurally Injected at Thoracic and Lumbar Vertebral Segments

Abstract

ABSTRACT. The epidural distribution of iohexol (0.2 ml/kg) administered at thoracic vertebrae (Thoracic group) and lumbar vertebrae (Lumbar group) was compared by computed tomographic (CT) epidurography in dogs. The total spread of iohexol was similar between the 2 groups upon reaching a similar cranial level. The maximal CT values were higher at the C7/T1 and T4/T5 levels in Thoracic group, but they were higher at the T13/L1 and L4/L5 levels in Lumbar group (P<0.05). This result suggests that the distribution pattern of the drug administered epidurally at thoracic vertebrae and lumbar vertebrae is different in dogs.

Use of Contrast‐enhanced Computed Tomography to Study the Cranial Migration of a Lumbosacral Injectate in Cadaver Dogs

“…Furthermore, this study provided evidence supporting the long‐standing belief that a 0.2‐ml/kg lumbosacral epidural injection travels to at least the TL junction in the majority of dogs. Findings from this study differed from those reported in a previous publication with respect to the total number of vertebral segments reached by the contrast medium cranial to the lumbosacral space . In the previous study, the median number of vertebral segments reached by the contrast medium was 18.5 at initial measurement, compared to a median of 7.2 segments in this study.…”

“…This type of advanced technique is rarely used in clinical practice, while the standard epidural needle technique used to deliver the injection in this study is more widely practiced in a clinical setting. Furthermore, the average weight of dogs used in the cited study was 12.0 kg, significantly less than the average weight of the dogs used in the current study (26.8 kg) . These variables likely contributed to the significant difference in vertebral segments reached by the contrast medium.…”

“…However, measurement was taken 5 min after the injection of contrast, compared to the measurement taken immediately after injection in this study . The previous study also used an epidural catheter to deliver the epidural, advancing the catheter 10 cm cranially into the epidural space . This type of advanced technique is rarely used in clinical practice, while the standard epidural needle technique used to deliver the injection in this study is more widely practiced in a clinical setting.…”

“…In the previous study, the median number of vertebral segments reached by the contrast medium was 18.5 at initial measurement, compared to a median of 7.2 segments in this study. However, measurement was taken 5 min after the injection of contrast, compared to the measurement taken immediately after injection in this study . The previous study also used an epidural catheter to deliver the epidural, advancing the catheter 10 cm cranially into the epidural space .…”

“…Radiography has been used previously to view the epidural column in vivo using cross‐table radiographs to evaluate an epidural injection of iodinated contrast medium mixed with new methylene blue dye . Computed tomography (CT) has also been used to examine the canine lumbosacral spine, as well as the epidural distribution of catheter‐injected iodinated contrast medium at various vertebral segments . This modality provides superior resolution and insight into the morphology of the epidural space than digital radiography and allows for the study of the space in three dimensions .…”