.png){kind=small}
.png){kind=small}
BackTable / MSK / Article
Evaluation of Discogenic Back Pain with CT Discography & Spectroscopy
Lilyrose Bahrabadi • Updated Jun 11, 2025 • 37 hits
Discogenic back pain remains one of the most common yet frequently misunderstood sources of chronic low back pain. Traditional diagnostic models often fall short in capturing the nuanced structural and biomechanical changes within the intervertebral disc, leading to missed or delayed diagnoses. Variability in symptoms based on fissure type, degree of annular disruption, and patient specific spinal loading patterns only further complicate clinical assessment.
In response to these complications physicians are now utilizing advanced diagnostic tools like anesthetic CT discography and MR spectroscopy to more precisely localize symptomatic discs, particularly in cases of multi-level degenerative disease. These modalities, when integrated with a focused physical examination and a deep understanding of disc biomechanics, offer a pathway towards more targeted and effective treatment. As these technologies continue to evolve, so too does the ability to accurately identify discogenic pain to improve patient outcomes.
This article features excerpts from the BackTable MSK Podcast. We’ve provided the highlight reel in this article, and you can listen to the full podcast below.
The BackTable MSK Brief
• Discogenic back pain is often underdiagnosed due to the limitations of traditional imaging and variability in symptom presentation.
• Traditional discography relied on provocative techniques to reproduce pain, often causing discomfort and leading to limited treatment decisions.
• Modern treatment protocols increasingly favor anesthetic discography, which uses anesthetic agents like lidocaine to identify symptomatic discs through functional pain relief.
• Physical exam findings, such as pain with axial loading or forward flexion, remain essential for identifying symptomatic discs.
• The Modified Dallas Discogram Scale helps stratify disc degeneration severity, guiding candidacy alongside CT discograms, for permanent implants.
• CT discography offers precise structural visualization and dynamic assessment, enhancing diagnostic accuracy.
• MR spectroscopy has become an emerging tool that detects metabolic markers like lactate levels, helping pinpoint pain generating discs in complex, multi-level cases.
• An integrated approach using physical exam, CT discography, and MR spectroscopy enable more personalized and effective treatment plans
Table of Contents
(1) Evolving Paradigms in Discography
(2) The Emerging Role of CT Discograms in Discogenic Pain Evaluation
(3) The Role of Spectroscopy in Identifying Target Discs in Multi-Level Degenerative Disc Disease
Evolving Paradigms in Discography
Discography has long been the diagnostic standard in evaluating discogenic back pain, particularly for identification of specific symptomatic discs, or assessment of annular integrity.
Conventional discography once relied on provocative methods, injecting contrast into the disc at high pressure to recreate pain. Although effective in pinpointing pain sources, this approach was often distressing for patients and narrow in focus, frequently resulting in stark choices: spinal fusion or no treatment.
Modern discography techniques now prioritize anesthetic discography, which involves injecting lidocaine to evaluate pain relief and determine if a specific disc is the pain source. This real-world feedback allows patients to help identify the source of their pain, and minimize discomfort during evaluation.
In addition to pinpointing pain origin, discography also plays an important role in evaluating structural disc integrity. Degenerative changes in a disc can lead to increased shear forces on delicate structures, internal collapse of spinal architecture, and more complex radial tears. These factors can now be assessed with more precision through the use of CT discography with 3D reconstruction. This imaging technique allows physicians to classify the type and severity of annular tears, in conjunction with systems like the Modified Dallas Discogram Scale. This detailed visualization is valuable when considering more invasive interventions – most notably the implantation of permanent devices or biomaterials to minimize pain or reinforce sites of annular tearing.
[Dr. Jacob Fleming]
You talk to most people about a discogram and an interventional radiologist who'd been in practice for a while, maybe did some of the old provocative discography and they're like, "Oh, it's the worst thing ever." You basically just try to pressurize the disc and see if it's painful for the patient. It's pretty brutal. That's what I would consider the old paradigm of provocative discography. Then you're basically seeing, okay, is that their source of pain? Historically, that's been used mostly to decide whether to fuse them.
That all or nothing approach. It's either do nothing or fuse them. I think hopefully that will change. I consider that the old paradigm, I consider the new paradigm or newer paradigm, the idea of anesthetic discography. Could you just tell us a little bit about that?
[Dr. Olivier Clerk-Lamalice]
Yes. Discogram overall is a diagnostic tool to confirm basically if the disintegration or the annular fissure is the source of pain of the patient. It provides another component also. This other important component is what type of tear also is seen within the architecture of the disc. One other thing that we haven't mentioned yet is that when the disc degenerates, it creates also other things on the segment. You do see a fair amount of instability that is caused by disc degeneration.
You lose inner architecture within the nucleus. You have the inner annulus fibrosis that will bow internally toward the nucleus. If you take a look on biomechanical studies, you'll see that the disc move in sheer motion with way greater amplitudes than a regular disc. That's something that we see also. We see that as the disc degenerates further, you see even a posterior loading on the facet joint and on the posterior portion of the disc, so on the posterior annulus.
Often at this point, you're going to see herniations appear, you're going to see tear appear, and those tears can be quantified and further characterized with the discogram. Originally, as you mentioned, the discogram was a provocative test or a stress procedure. We were injecting contrast under pressure, under a certain pressure to determine if the patient has pain while injecting. It could be a pretty brutal test. We were increasing pressure, up to 50 PSI to try to determine if that was the pain generator for a patient.
This is something that we're trying to do less and less. We're trying to do a negative discogram, which is actually just injecting lidocaine within the disc to determine if the patient has relief of his pain. In my opinion, this is a better way to determine if this is a pain generator of the patient because he can try it out at home. He can go back home, go back with a pain journal, and for a couple of hours, determine if his maneuvers that normally would be painful, so bending forward, sitting, being in transit in between the clinic and his apartment hurts less with the freezing in place.
That's a better way to determine if this is the pain generator. Then the other component is to determine the type of tear. This is something that we can see and quantify with a CT discogram. We can even do a 3D recon after injecting dye within the disc. There's different types of classification that allows us to determine the type of tear. This is also a test that is more and more important as we are injecting permanent implants or permanent biomaterial within the disc. You want to make sure that it stays within the border of the annulus and you want to stress this annulus, making sure that this annulus is competent. There's different types of tear, different classification that use a classification called the Modified Dallas Discogram Scale that we use on a fairly regular basis now to be able to determine if those patients will sustain the stress of injecting something within the content of that disc.
[Dr. Jacob Fleming]
Excellent. I'm glad you brought up the concept of CT. Those of our colleagues who've done CT myelograms before, this will make perfect sense. I haven't personally done any of these yet, but I'm looking forward to starting it in my new practice because I think you can get so much information from these. Can you tell us just a little bit about how do you do a CT discogram in your practice? Do you routinely do that on all patients or just in certain situations?
Listen to the Full Podcast
Stay Up To Date
Follow:
Subscribe:
Sign Up:
The Emerging Role of CT Discograms in Discogenic Pain Evaluation
When evaluating candidates for permanent intradiscal implants, such as hydrogels or other biomaterials, it is essential to carefully assess the integrity of the annulus to minimize the risk of implant expulsion. The Modified Dallas Discogram scale, coupled with CT discography, can be used to categorize annular tears from grade zero (normal disc) to grade five (contrast extravasation into the epidural space).
Most degenerated discs will fall within grades three and four. A grade three tear will extend to the outer third of the annulus with minimal circumferential involvement of less than 30%, while a grade four indicates more substantial circumferential tears exceeding 30%. Candidates within these grades are still considered as potential implant candidates, however grade five tears are considered exclusionary for implant therapy as they signify a breach of containment.
It is important to note that dynamic changes in disc morphology due to a patient's positioning can impact these assessments. Axial loading during upright activity such as walking, can escalate a disc’s grade when in contrast to their previous supine positioning, revealing an occult instability. This practice of incorporating dynamic stress into the evaluation process is becoming a pivotal advancement in the utilization of CT discograms in pain evaluation, offering more accurate assessments of annular competence and implant suitability.
[Dr. Olivier Clerk-Lamalice]
Mainly in patients that we think that we want to proceed with a permanent implant. Intradiscal hydrogel or other type of implants that we have access to. Whenever we're concerned that there may be, we want to make sure there's no expulsion of that implant. There's five grading scale that we utilize. Grade zero of the Modified Dallas Discogram Scale, which is a normal disc. Grade one, you're going to have a small fissure mainly centrally.
Grade two, you're going to have a radial fissure that can extend up to the middle third of the annulus. Grade three, up to the outer third of the annulus. Sometimes you may see a little bit of a circumferential tear along the outer annulus, but it should be less than 30%. Whenever you're in a grade four, you have more than 30% of this outer circumference tear. These are the most frequently seen tears.
I would say in a degenerated disc, more frequently than not, it's going to be a grade three or a grade four. That's going to be the differential to the two types that we want to differentiate. The grade five is probably the most important to diagnose. The grade five, you're going to have extravasation of contrast within the ventral epidural space. Whenever you do see that, this is a no-go. You don't want to inject those patients with any type of hydrogel or any type of permanent implant.
What we discovered after doing multiple hundreds and thousands of them, one point that is often forgotten is that you're injecting this dye with a patient that is in a supine position. That is prone, so on their stomach, which is very different than if you're stressing the disc. What we noted is just the fact in between the procedural room and the CT scan, just the fact of walking less than a hundred meters, just that axial compression in some case would upgrade the discogram scale.
The patient may pass from a grade three to a grade five or grade four to grade five. That axial loading on the disc that contain contrast is important because now you're really able to determine if this disc is patentable. That's something that we discovered while gaining experience while doing that. To me, this has been a practice, a game changer, because now we're virtually stressing all discogram like that to make sure that they are fully competent to receive an implant.
[Dr. Jacob Fleming]
So interesting, and such an important part about the dynamic aspect of the disc. You alluded to this earlier, talking about some of the anatomic ramifications, as you said, with the instability that arises, experienced shear forces. One of the things that mystified me for the longest time was this phenomenon of what's sometimes called vacuum disc. We see this often in the supine patients, like you said, can you tell us a little bit about the significance of that particular finding?
The Role of Spectroscopy in Identifying Target Discs in Multi-Level Degenerative Disc Disease
MRI Disc Spectroscopy is also emerging as a promising advancement in the evaluation of multi-level degenerative disc disease, offering a molecular level perspective that enhances diagnostic precision. MRI spectroscopy has proven to be particularly useful when high specificity is required for therapeutic planning, enabling noninvasive detection of metabolic changes within the disc – including the presence of lactate and alterations in the proteoglycan to lactate ratio. Elevated lactate levels reflect increased reliance on anaerobic glycolysis, indicative of an avascular and degenerative environment, particularly within the nucleus pulposus. While not necessary for every patient, MRI disc spectroscopy has provided valuable insight in cases where standard imaging and clinical examination are inconclusive or when targeting a specific disc for integration is absolutely essential.
Though MR spectroscopy holds promise for identifying symptomatic discs, especially in patients with multi-level disease, its role in diagnosing discogenic back pain remains underutilized and even controversial. Physicians can, and frequently do, still employ conventional discography in cases where MRI disc spectroscopy may not be indicated, injecting multiple levels and evaluating for concordant pain responses before considering further diagnostic steps. Although this method is practical and informative, spectroscopy may become increasingly relevant as part of a hybrid strategy for diagnosis, especially when narrowing down candidates for biological implants or disc targeted therapies.
[Dr. Olivier Clerk-Lamalice]
The other modality that can be useful is spectroscopy. Spectroscopy also that we do can be useful also to determine if there's presence mainly of some lactate markers. Normally you're going to see a reversal of the ratio between proteoglycans and lactate. That can be useful as well. It does take time. We don't do it on every patient, but we do it sometimes whenever there's a good reason to be extremely precise within the disc that we want to treat.
[Dr. Jacob Fleming]
Thanks for that excellent overview. Thank you for the allusion to MR spectroscopy of the disc. This is one of my nerdy radiology interests I get really interested about. I remember I told one of my, one of my co-residents, who's one of the smartest people I know, he is a neuroradiologist now, but I mentioned to this, I had learned about it at ASSR a few years ago. It necessitates a show of its own, but basically I was telling my friend about this.
I'm like, oh yes, some people are using MR spectroscopy on the disc to look at the different ratios of molecules and meteors and figure out what is the symptomatic level. He was like, "No, they're not."
[Dr. Olivier Clerk-Lamalice]
Yes, he can.
[Dr. Jacob Fleming]
From a neuroradiologist.
[Dr. Olivier Clerk-Lamalice]
He totally can.
[Dr. Jacob Fleming]
That's silly. That doesn't make any sense.
[Dr. Olivier Clerk-Lamalice]
He totally can.
[Dr. Jacob Fleming]
To you and me and anyone who treats patients with low back pain, it's like, yes, that has a potential to be a real game changer. Of course, I think there are some situations, I don't have that available currently. I definitely, in the patient who has a multi-level disease, I opt for starting off with what I refer to as a shotgun approach. Basically you have a shotgun approach to discography where you inject all the discs and we'll get into the actual technique momentarily, but inject each of those levels. You look for a pain response at each level as well. That gives you more information, even though you're injecting all of them.
For example, I did a three-level discogram on a gentleman a few weeks ago, bottom three levels and similar situation to what we were discussing. When I injected four, five, he almost jumped off the table, despite the fact he was sedated. I knew he was exceptionally tender there. That gives me some more insight into, okay, he may be symptomatic from all three levels to a degree, but that one seems to, by and large. Still, I didn't know that beforehand.
I started off with the shotgun approach. That's pretty much, I think, what you and I have both been taught to do. The practice that I keep. I contrast that with, of course, what Dr. Beal refers to as the hunt and peck approach. That's basically when you are maybe moving towards doing something like an implant or a therapeutic injection, and you may do literally one level at a time and allow the patient to go through the formal process, recover from sedation, see if they feel better, and you can go down the list.
Honestly, it's been relatively few times that I've ever had to do that, where you inject a patient more than once. Usually there's other things like that, like the concordant pain response being related more to one level. I find that those things give you so much additional information that even though you start off with this challenging diagnostic test of figuring out what is the symptomatic level among many levels, if you start off with the shotgun approach, it will almost invariably lead you towards the answer. That's just my opinion.
Podcast Contributors
Dr. Olivier Clerk-Lamalice
Dr. Olivier Clerk-Lamalice is an interventional radiologist that specializes in interventional pain management and diagnostic imaging in Calgary, Canada.
Dr. Jacob Fleming
Dr. Jacob Fleming is a diagnostic radiology resident and future MSK interventional radiologist in Dallas, Texas.
Cite This Podcast
BackTable, LLC (Producer). (2025, February 4). Ep. 67 – Introduction to Treatment of Discogenic Back Pain [Audio podcast]. Retrieved from https://www.backtable.com
Disclaimer: The Materials available on BackTable.com are for informational and educational purposes only and are not a substitute for the professional judgment of a healthcare professional in diagnosing and treating patients. The opinions expressed by participants of the BackTable Podcast belong solely to the participants, and do not necessarily reflect the views of BackTable.
Podcasts
