Article Figures & Data
Figures
- Fig 1.
Mixed intravascular and epidural contrast injection. A, Intravascular injection appears as discrete foci of contrast (arrowheads) away from the needle tip and adjacent main, epidural contrast collection. B, The intravascular contrast almost completely disappears (arrowheads) on immediate repeat CT-fluoroscopic imaging. This rapid resolution of contrast confirmed but was not required for identification of intravascular contrast. The needle tip position is junctional on these images.
- Fig 2.
Intravascular injection identified by a less-than-expected accumulation of epidural contrast. A, Needle position before the contrast trial dose. B, Only a very small amount of contrast, considerably less than the injected volume of 0.3 mL of iohexol, is seen on immediate postinjection imaging. The missing contrast is inferred to be intravascular and has been circulated out of the imaged field. (A trace amount of intravascular contrast is also noted within the right aspect of the spinal canal.) C, After the needle is withdrawn several millimeters, a repeat contrast trial injection shows the expected volume of injected contrast accumulating in the epidural space. No additional intravascular contrast was identified with the steroid/analgesic injection (not shown), making this a trial dose intravascular injection.
- Fig 3.
Intravascular contrast injection classified by volume. A, Trace volume of intravascular injection appears as 1–2 subtle foci (arrowheads), each ≤2 mm. The image is windowed to accentuate the intravascular contrast; the initial appearance on default window settings is even subtler and was not identified at the time of the procedure. B, A small volume of intravascular injection appears either as ≥3 foci (arrowheads), at least 1 focus of ≥3 mm (central arrowhead), or both (as in this case). C, A large volume of intravascular contrast injection. Less than the expected volume of injected iohexol is seen on the imaging because most of the intravascular contrast has already been circulated out of the FOV. Some intravascular contrast is present within the venous plexus both adjacent to the needle tip and more medially (arrowheads).
- Fig 4.
Intravascular injection seen only on steroid/analgesic injection. A, Needle position preinjection. B, Contrast trial injection shows no intravascular injection. C, Subsequent injection of the steroid/analgesic cocktail shows a small intravascular injection (arrowhead) within an indeterminate paraspinal vessel. The needle was unchanged in position between trial injection and steroid/analgesic cocktail injection.
- Fig 5.
Intravascular injection on both trial injection and steroid/analgesic cocktail injection. A, The trace intravascular injection (arrowhead) is subtle but present on the contrast trial dose; the proceduralist did not appreciate it at the time of the procedure. B, More obvious intravascular injection (arrowhead) is evident on the ensuing steroid/analgesic cocktail injection.
- Fig 6.
Classification of intravascular injection by vessel type. A, Venous injection, with contrast within extracanalicular and intracanalicular (arrowhead) components of the venous plexus. B, Indeterminate vessel injection, with contrast accumulating within a small paraspinal vessel (arrowhead). This could represent either a branch of the ascending cervical artery or a small vein. No likely arterial injections were identified.
- Fig 7.
Needle depth classification. A, The lateral junction of the neural foramen (dotted line) is defined by a line segment connecting the anterolateral margin of the vertebral body with the most lateral margin of the facet joint. A needle tip in a zone within 2 mm medial or lateral to this segment (solid lines) is classified as within the junctional zone (J). A needle tip >2 mm lateral is classified as within the extraforaminal zone (E), and a needle tip >2 mm medial is classified as within the foraminal zone (F). Examples of extraforaminal (B), junctional (C), and foraminal (D) needle tip positions.
