Low back pain diagnosis – CT or MRI?

14th November 2025, NIA Diagnostic Imaging

Lower back pain (LBP) remains one of the most common presentations in general practice and a major cause of disability worldwide. (3) While most cases are non-specific and self-limiting, imaging can be valuable when serious underlying pathology is suspected or symptoms persist beyond the usual recovery period. The two key imaging modalities utilised to diagnose LBP are computed tomography (CT) and magnetic resonance imaging (MRI). Understanding the benefits and limitations of these modalities is crucial for making appropriate, evidence-based decisions that result in an accurate diagnosis as well as patient care and satisfaction. (1)

CT VS MRI: BRIEF OVERVIEW

Although both CT and MRI generate comprehensive cross-sectional pictures, each modality possesses distinct benefits and limitations in the clinical assessment of lower back pain. The following table summarises the various features offered by each modality:

CHOOSING THE RIGHT MODALITY

In diagnosing back pain, the choice between MRI and CT is dependent on the suspected cause of pain. Ultimately, MRI is the golden standard for assessing soft tissue structures, including vertebral discs, nerves, and muscles. Some conditions involving these structures would include herniated discs, spinal stenosis and degenerative disc disease. On the other hand, CT is more suited to examining and detecting bone-related issues, including fractures or spinal malalignment. Due to its speed and high resolution for bony structures, CT is often the preferred option in emergency settings, especially for trauma cases. (2,5)

CASE STUDY

A 38-year-old male presented to our clinic with bilateral leg radiculopathy and lower back pain after being assaulted at work. An initial CT scan revealed that the patient had multilevel disc bulging, with no evidence of fractures or nerve root impingement.

A week later, the patient returned to our clinics and underwent an MRI scan. The MRI demonstrated that the patient
had a disc desiccation and an annular disc tear at L5/S1, as well as disc bulging at L3/4, potentially impinging on the
origin of the right L4 nerve root.

CONCLUSION
In conclusion, the decision to use CT or MRI for diagnosing lower back pain should be guided by the clinical context. While CT is particularly useful for identifying bone-related issues, MRI is better suited for assessing soft tissue
structures, including discs, nerves, and the spinal cord. As demonstrated in the case study, MRI is capable of depicting soft tissue details that were not apparent on the CT scan. Therefore, choosing the right imaging technique is crucial for achieving an accurate diagnosis, which in turn ensures effective management of the patient’s condition.

REFERENCES
Australian Commission on Safety and Quality in Health Care. (2022). Low Back Pain Clinical Care Standard. https://www.safetyandquality.gov.au/sites/default/files/2022-08/low_back_pain_clinical_care_standard.pdf
Hussain, O., Kaushal, M., Agarwal, N., Kurpad, S., & Shabani, S. (2023). The Role of Magnetic Resonance Imaging and Computed Tomography in Spinal Cord Injury. Life, 13(8), 1680. https://doi.org/10.3390/life13081680
Hutchins, T. A., Peckham, M., Shah, L. M., Parsons, M. S., Agarwal, V., Boulter, D. J., Burns, J., Cassidy, R. C., Davis, M. A., Holly, L. T., Hunt, C. H., Khan, M. A., Moritani, T., Ortiz, A. O., O’Toole, J. E., Powers, W. J., Promes, S. B., Reitman, C., Shah, V. N., & Singh, S. (2021). ACR Appropriateness Criteria® Low Back Pain: 2021 Update. Journal of the American College of Radiology, 18(11), S361–S379. https://doi.org/10.1016/j.jacr.2021.08.002
RACGP – Imaging in adults with acute low back pain. (2018). Racgp.org.au. https://www.racgp.org.au/clinical-resources/clinicalguidelines/key-racgp-guidelines/view-all-racgp-guidelines/first-do-no-harm/gp-resources/imaging-in-adults-with-acute-low-backpain
Ruiz Santiago, F., Láinez Ramos-Bossini, A. J., Wáng, Y. X. J., Martínez Barbero, J. P., Espinosa, J. G., & Martínez Martínez, A. (2022). The value of magnetic resonance imaging and computed tomography in the study of spinal disorders. Quantitative Imaging in Medicine and Surgery, 12(7), 3947–3986. https://doi.org/10.21037/qims-2022-04
Stallard, J. (2019, May 10). CT vs MRI: What’s the Difference? And How Do Doctors Choose Which Imaging Method to Use? Memorial Sloan Kettering Cancer Center. Www.mskcc.org. https://www.mskcc.org/news/ct-vs-mri-what-s-difference-and-how-dodoctors-choose-which-imaging-method-use

PFO Closure

Furlan AJ, Reisman M, Massaro J, et al. Closure or medical therapy for cryptogenic stroke with patent foramen ovale. N Engl J Med 2012; 366: 991–

A multicenter, randomized, open-label trial of closure with a percutaneous device, as compared with medical therapy alone, in patients between 18 and 60 years of age who presented with a cryptogenic stroke or transient ischemic attack (TIA) and had a patent foramen ovale. The primary end point was a composite of stroke or transient ischemic attack during 2 years of follow-up, death from any cause during the first 30 days, or death from neurologic causes between 31 days and 2 years.

Results:

Primary end point was 5.5% in the closure group as compared with 6.8% in the medical-therapy group (adjusted hazard ratio, 0.78; 95% confidence interval, 0.45 to 1.35; P = 0.37)

Conclusion:

“In patients with cryptogenic stroke or TIA who had a patent foramen ovale, closure

with a device did not offer a greater benefit than medical therapy alone for the

prevention of recurrent stroke or TIA”

2 Saver JL, Carroll JD, Thaler DE, et al. Long-term outcomes of patent foramen ovale closure or medical therapy after stroke. N Engl J Med 2017; 377: 1022–

A multicenter, randomised, open-label trial ,randomly assigned patients 18 to 60 years of age who had a patent foramen ovale (PFO) and had had a cryptogenic ischemic stroke to undergo closure of the PFO (PFO closure group) or to receive medical therapy alone (aspirin, warfarin, clopidogrel, or aspirin combined with extended-release dipyridamole; medical-therapy group). The primary efficacy end point was a composite of recurrent nonfatal ischemic stroke, fatal ischemic stroke, or early death after randomisation.

Results:

Recurrent ischemic stroke occurred in 18 patients in the PFO closure group and in 28 patients in the medical-therapy group, resulting in rates of 0.58 events per 100 patient-years and 1.07 events per 100 patient years, respectively (hazard ratio 0.55; 0.31 – 0.999; P = 0.046)

Conclusion:

“Among adults who had had a cryptogenic ischemic stroke, closure of a PFO was associated with a lower rate of recurrent ischemic strokes than medical therapy alone during extended follow-up.”

Meier B, Kalesan B, Mattle HP, et al. Percutaneous closure of patent foramen ovale in cryptogenic embolism. N Engl J Med 2013; 368: 1083–

A prospective, multicenter, randomised, event-driven trial, randomly assigned patients to medical therapy alone (anti-platelet or warfarin therapy) or closure of the patent foramen ovale.

Results:

9 patients in the closure group and 16 in the medical-therapy group had a recurrence of stroke (hazard ratio with closure, 0.49; 0.22 – 1.11; P = 0.08). The primary analysis of the intentionto- treat cohort showed a nominal 51% hazard rate reduction with closure, but the reduction did not reach significance.

Conclusions:

” …there was no significant benefit associated with closure of a patent foramen ovale in adults who had had a cryptogenic ischaemic stroke.”

Sondergaard L, Kasner SE, Rhodes JF, et al. Patent foramen ovale closure or antiplatelet therapy for cryptogenic stroke. N Engl J Med 2017; 377: 1033–

Multinational trial involving patients with a PFO who had had a cryptogenic stroke, randomly assigned patients to undergo PFO closure plus antiplatelet therapy or to receive antiplatelet therapy alone.

Results:

During a median follow-up of 3.2 years, clinical ischemic stroke occurred in 6 of 441 patients (1.4%) in the PFO closure group and in 12 of 223 patients (5.4%) in the antiplatelet-only group (hazard ratio, 0.23; 0.09 to 0.62; P=0.002).

Conclusions:

“Among patients with a PFO who had had a cryptogenic stroke, the risk of subsequent ischemic stroke was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone; however, PFO closure was associated with higher rates of device complications and atrial fibrillation.”

Mas JL, Derumeaux G, Guillon B, et al. Patent foramen ovale closure or anticoagulation vs. antiplatelets after stroke. N Engl J Med 2017; 377: 1011–

In a multicenter, randomised, open-label trial patients 16-60 years of age who had had a recent stroke attributed to PFO, to transcatheter PFO closure plus long-term antiplatelet therapy, antiplatelet therapy alone or oral anticoagulation.

Results:

No stroke occurred among patients in the PFO closure group, whereas stroke occurred in 14 of the 235 patients in the antiplatelet- only group (hazard ratio, 0.03; 0 to 0.26; P<0.001). Large number of patients discontinued anti-coagulation in the anti-coagulant group and statistical significance was not analysed because the study was not adequately powered to compare outcomes.

Conclusion:

“Among patients who had had a recent cryptogenic stroke attributed to PFO with an associated atrial septal aneurysm or large interatrial shunt, the rate of stroke recurrence was lower among those assigned to PFO closure combined with antiplatelet therapy than among those assigned to antiplatelet therapy alone. PFO closure was associated with an increased risk of atrial fibrillation.”

Lee PH, Song J-K, Kim JS, et al. Cryptogenic stroke and high-risk patent foramen ovale: the DEFENSE-PFO Trial. J Am Coll Cardiol 2018; 71: 2335–

Patients with cryptogenic stroke and high-risk PFO were divided between a transcatheter PFO closure and a medication-only group.

Results:

No events occurred in the PFO closure group. 12.9% of patients in the medication group had an event (p= 0.023).

Conclusion:

“PFO closure in patients with high-risk PFO characteristics resulted in a lower rate of the primary endpoint as well as stroke recurrence”