Approach to Spine CT & Radiographs
- Radiographs and CT are the bone people of spine imaging; for cord, discs, and ligaments you want MRI.
- CT has all but replaced plain films for spine trauma — it sees fractures the eye on radiographs misses.
- Read every spine study the same boring way every time: alignment, bones, joints, spaces. Boring is how you stop missing things.
- Check alignment by tracing smooth lines down the column. A step in the line is a step you cannot ignore.
- Always count your levels and name them correctly. "Something's broken somewhere around the middle" is not a report.
Think of the spine as a stack of children's blocks (the vertebral bodies) with little jelly cushions between them (the discs), all zip-tied together by ligaments, with a precious cable — the spinal cord — threaded up the middle. Radiographs and CT are fantastic at the blocks. They are nearly blind to the cushions, the zip ties, and the cable. Knowing what each test can and can't see is honestly half the battle, so let's start there.
What each tool actually sees
X-rays only really care about one thing: density. Bone eats lots of the beam and shows up white; everything soft — cord, discs, ligaments, nerves — blurs together into an indistinct gray. So a radiograph is a bone-and-alignment tool. It's quick, cheap, and great for a first look at posture, hardware, and obvious breaks.
CT is the same physics with superpowers: hundreds of thin slices the computer can stack and reformat into any plane you like. It still loves bone above all, but the detail is dramatically better — you can chase a fracture line across a vertebra and actually see whether a fragment has wandered back toward the cord.
If the clinical question is about the cord, the discs, the ligaments, or marrow — pain shooting down a leg, weakness, suspected infection — CT is the wrong hammer. That's an MRI question. CT and radiographs answer bony questions.
The ABCs: read it the same way every single time
Here's the secret the attendings won't admit is a secret: they're not smarter than you, they're just consistent. They run the same checklist on every study so nothing slips through. Steal their checklist. I use Alignment, Bones, Cartilage/joints, Spaces (soft tissue) — ABCS.
| Step | What you're checking | The thing that makes you nervous |
|---|---|---|
| Alignment | Are the smooth lines smooth? | A step-off, a slip, abnormal curve |
| Bones | Each vertebra's shape and density | A lucent or sclerotic line, a squashed body |
| Cartilage/joints | Disc heights, facet joints | Widened or "jumped" facets, lost disc space |
| Spaces | Soft tissues and gaps around the bones | Prevertebral swelling, a widened space between spinous processes |
Alignment: trace the lines like a kid's maze
On a normal lateral cervical radiograph you can draw three (sometimes four) gentle, parallel curves that flow down the neck without a hitch: the anterior vertebral body line, the posterior vertebral body line, and the spinolaminar line at the back of the canal. Picture three lanes of a curving highway — every car (vertebra) should stay in its lane.
A sudden jog in any of these lines is your alarm bell. A vertebra sliding forward on the one below it is a listhesis; a clean step in the posterior line can mean the column has shifted in a way the cord won't appreciate.
On a cervical radiograph, glance at the prevertebral soft tissue in front of the spine. A suspiciously fat soft-tissue stripe can be the only hint of a fracture you can't directly see — like noticing a swollen ankle before you've found the sprain.
Bones and joints: count, then inspect
First, count your levels and name them — C, T, L, S — so your finding has an address. "A compression fracture" helps nobody; "an L1 compression fracture" sends the right patient to the right place.
Then look at each vertebral body's shape. A normal body is a tidy rectangle. When one looks squashed, wedged, or shorter than its neighbors, you're likely looking at a compression or burst fracture — and CT is the test that tells you whether a fragment has been pushed back into the spinal canal. While you're there, check the disc spaces and the facet joints: facets should overlap like neatly stacked roof shingles, not gape apart.
Don't call a fracture without considering the mimics. Normal growth lines in kids, bony variants, and degenerative spurs all fake breaks. And the cervicothoracic junction (around C7–T1) is notorious for hiding behind the shoulders on radiographs — if you can't see it clearly, you haven't cleared it. That junction is exactly why trauma protocols lean so heavily on CT.
CT is the trauma workhorse — and radiographs still have a job
For significant trauma, CT has largely taken over: it catches fractures radiographs miss and lets you rebuild the spine in three dimensions. The rules for whether a trauma patient even needs imaging are their own art — that's the world of cervical spine clearance.
That doesn't make radiographs useless. They shine for quick checks of alignment and hardware, for follow-up, and — uniquely — for flexion-extension or upright weight-bearing views, where you watch the spine move or bear load to expose instability that a patient lying flat in a CT scanner will hide.
CT and radiographs are your bone-and-alignment instruments. Run ABCS the same way every time, count and name your levels, trace the alignment lines for step-offs — and the moment the question turns to cord, disc, or ligament, switch to MRI.