What MRI is indicated for lower back pain with a bulging intervertebral disc (IVD)?

From the Guidelines

For lumbar pain with a suspected bulging disc, a standard lumbar spine MRI without contrast is typically the recommended imaging study. This recommendation is based on the most recent and highest quality study, which suggests that MRI is the initial imaging modality of choice for patients with subacute or chronic low back pain who have failed 6 weeks of conservative therapy 1. The MRI should include T1-weighted and T2-weighted sequences in multiple planes (axial, sagittal, and sometimes coronal views) to properly visualize the spinal canal, neural foramina, intervertebral discs, and surrounding soft tissues.

The American College of Radiology recommends MRI lumbar spine without IV contrast as the initial imaging for patients with subacute or chronic low back pain with or without radiculopathy who are candidates for surgery or intervention with persistent or progressive symptoms during or following 6 weeks of optimal medical management 1. This is because MRI provides excellent soft tissue detail, allowing clear visualization of disc material, nerve roots, and potential compression, which is essential for identifying potential actionable pain generators that could be targeted for intervention or surgery 1.

Some key points to consider when ordering an MRI for lumbar pain with a suspected bulging disc include:

• The MRI should cover the entire lumbar spine (L1 to S1) to ensure all potential problem areas are visualized, including any transitional vertebrae if present.
• Patients should inform the radiologist about any metal implants, pacemakers, or claustrophobia before the procedure, as these may require special protocols or alternative imaging approaches.
• If there's concern about inflammation or infection, your doctor might order an MRI with gadolinium contrast, but this is not routine for simple disc bulges.
• CT scans may be used as an alternative imaging modality in certain situations, such as when MRI is contraindicated or not available, but they are not the preferred initial imaging modality for lumbar pain with a suspected bulging disc 1.

From the Research

MRI Protocols for Lumbar Pain with Bulging Disc

• The study 2 suggests that a single sagittal T2-weighted Dixon sequence may replace the recommended combination of T1-, T2-, and fat-suppressed T2-weighted sequences for the workup of degenerative lumbar spine lesions.
• The research 3 found that limited protocol MRI, using only sagittal T2-weighted imaging, may replace full protocol MRI in the diagnosis of lumbar disc herniation, but not in the diagnosis of nerve root compression.
• The study 4 determined that axial T1-weighted imaging does not add diagnostic value to routine lumbar spine MRI, suggesting that it may be redundant in the diagnosis of lower back pain.
• The evidence 5 supports the use of deep learning models for the automatic quantification and classification of lumbar disc herniation on axial magnetic resonance images, demonstrating high performance and consistency with expert classification.
• The research 6 used kinematic magnetic resonance imaging (kMRI) to quantify the bulging of degenerative intervertebral lumbar discs in vivo, finding that disc bulging increases with the severity of disc degeneration and that degenerative discs behave less predictably in response to postural loads.

Diagnostic Performance of MRI Protocols

• The study 2 found that the simplified protocol, using a single sagittal T2-weighted Dixon sequence, provides the same information as the standard protocol, including T1-, T2-, and fat-suppressed T2-weighted sequences, for the workup of degenerative lumbar spine lesions.
• The research 3 reported that the limited protocol MRI had a sensitivity of 82.61% and a specificity of 80% in the diagnosis of lumbar disc herniation, similar to the full protocol MRI.
• The evidence 4 showed that there was no difference in diagnostic performance between the interpretation of lumbar spine MRI with and without axial T1-weighted imaging.
• The study 5 demonstrated that the automated aided diagnostic model achieved high performance in detecting and classifying lumbar disc herniation, with a precision of 81.21% and 74.50% in the internal and external test sets, respectively.

Kinematic Behavior of Degenerative Intervertebral Discs

• The research 6 found that moderately degenerated intervertebral discs (grade III and IV) demonstrated greater bulging than mildly degenerated discs (grade II), and that severely degenerated discs (grade V) showed a trend toward greater bulging.
• The study 6 also reported that grade I discs moved posteriorly in flexion and anteriorly in extension, while mild to severe (grade II-V) degenerative discs behaved differently in response to postural loads, with extension resulting in significant posterior bulging.