MRI of the Lateral Knee for Suspected Iliotibial Band Syndrome
For suspected IT band syndrome, obtain an MRI of the lateral knee without contrast, focusing on coronal T2-weighted fat-saturated sequences to visualize fluid or edema deep to the iliotibial band adjacent to the lateral femoral epicondyle.
Primary Imaging Target and Sequences
The key anatomic region to image is the lateral compartment of the knee, specifically the area between the iliotibial band and the lateral femoral epicondyle 1, 2.
Essential MRI Sequences
- Coronal T2-weighted images with fat saturation are the most critical sequences, demonstrating ill-defined areas of high signal intensity in the soft tissues immediately below the iliotibial band lateral to the external femoral condyle 1, 2
- Axial fast imaging with steady-state precession (FISP) gradient-echo sequences are essential for differentiating the signal abnormality associated with IT band syndrome from fluid in the lateral knee joint 2
- T1-weighted images show ill-defined decreased signal intensity deep to the iliotibial band 2
Specific MRI Findings to Identify
Primary Diagnostic Features
- Fluid or edema deep to the IT band: Signal consistent with fluid is seen in the potential space (bursa) between the iliotibial band and the knee capsule in the region of the lateral femoral epicondyle 2, 3
- IT band thickening: Patients with IT band syndrome demonstrate significantly thicker iliotibial bands (5.49 ± 2.12 mm) compared to normal controls (2.52 ± 1.56 mm) over the lateral femoral epicondyle 3
- Soft-tissue edematous swelling or discrete fluid collection suggestive of bursitis between the iliotibial band and lateral femoral epicondyle 4
Secondary Findings
- Osseous edema in the lateral femoral condyle may be present 1
- Subchondral osseous erosion of the external femoral condyle can occur in some cases 1
Contrast Administration
IV contrast is not necessary for diagnosing IT band syndrome 5. The ACR Appropriateness Criteria indicate that IV contrast is rarely needed for MRI evaluation of extra-articular soft tissue abnormalities like tendonitis and bursitis 5.
Critical Differential Diagnoses to Exclude
MRI plays a significant role in differentiating IT band syndrome from other causes of lateral knee pain 1:
- Lateral meniscal tears (should be absent in pure IT band syndrome) 2
- Meniscal cysts 6
- Lateral collateral ligament injury 6
- Segond fracture 6
Common Pitfalls to Avoid
- Mistaking joint fluid for IT band pathology: Without axial FISP sequences, the ill-defined signal abnormality can be confused with lateral knee joint fluid 2
- Assuming thickening is always present: While IT band thickening is common, it has been inconsistently reported and may not be present in all cases 4
- Overlooking the bursal nature: The pathology occurs within a bursa beneath the iliotibial band, not within the knee joint itself 3
Clinical Context for Imaging
MRI is primarily indicated when: