From the Guidelines
An MRI is the preferred imaging modality for lumbar pain, as it provides superior visualization of soft tissues, including intervertebral discs, nerve roots, and the spinal cord, compared to a CT scan. This is because MRI has excellent soft-tissue contrast and accurately depicts lumbar pathology, including disc degeneration, as well as the thecal sac and neural structures 1. While CT scans are useful for evaluating bone structures, fractures, and calcifications, they have limitations in soft tissue contrast. MRI is particularly helpful when there is lumbar pain with radiculopathy or signs of spinal stenosis, which suggests the presence of demonstrable nerve root compression 1.
Some key advantages of MRI over CT scans for lumbar pain include:
- Superior soft-tissue contrast
- Ability to capture images in multiple planes without repositioning the patient
- No use of radiation
- Better detection of disc herniations, spinal stenosis, nerve compression, and inflammatory conditions
However, there are situations where CT may be preferred, such as:
- Evaluating for acute fractures
- When MRI is contraindicated, like in patients with certain implanted devices
- When patients cannot remain still for the longer MRI procedure
- Preoperative planning, where CT can delineate osseous margins and aid in trajectory planning for hardware fixation 1.
Overall, the choice between MRI and CT scan for lumbar pain depends on the specific clinical scenario and the patient's individual needs, but MRI is generally the preferred imaging modality due to its superior soft-tissue contrast and ability to detect a wide range of lumbar pathologies.
From the Research
Diagnostic Imaging for Lumbar Pain
- MRI is considered the diagnostic imaging examination of choice in lumbar spine evaluation of low back pain 2
- CT scans can be as sensitive as lumbar MRI in the evaluation of most items, excluding Modic changes, degenerative changes, signal of the disc, and disc herniation 2
- The agreement between MRI and CT in most items is substantial or almost perfect, with a Cohen's kappa-coefficient > 0.8, excluding certain conditions such as Modic changes and disc herniation 2
Comparison of CT and MRI
- CT shows high values of sensitivity and specificity (>80%) in most items evaluated, but sensitivity is low for the evaluation of density of the disc (40%) and for the detection of disc herniation (55%) 2
- MRI is more effective in detecting certain conditions such as Modic changes, degenerative changes, signal of the disc, and disc herniation 2
- The use of CT scans can help reduce MRI waiting lists and prioritize other patients with more severe pathology than LBP 2
Clinical Guidelines
- Advanced imaging studies, including CT and MRI, are frequently ordered in the setting of low back pain, but structural abnormalities are commonly identified in asymptomatic patients 3
- Guidelines have been published to help providers identify patients in whom the use of advanced imaging is appropriate 3