What is the preferred imaging modality, CT (Computed Tomography) scan or MRI (Magnetic Resonance Imaging), for evaluating Greater Trochanteric Pain Syndrome (GTPS)?

MRI vs CT for Greater Trochanteric Pain Syndrome (GTPS)

MRI is the preferred imaging modality for evaluating Greater Trochanteric Pain Syndrome (GTPS) after initial radiographs, as it provides superior assessment of soft tissue abnormalities including gluteal tendinopathy, bursitis, and muscle pathology. 1

Imaging Algorithm for GTPS

First-Line Imaging

• Radiographs should be obtained first in most cases to rule out other causes of hip pain and provide a baseline assessment 1, 2
• Radiographs serve as an excellent screening tool but have limited value for soft tissue evaluation 1

Second-Line Imaging

• MRI is the recommended modality after radiographs for suspected GTPS for the following reasons:
  • Superior soft tissue evaluation compared to CT 1
  • Highly sensitive and specific for detecting soft tissue abnormalities 1
  • Can comprehensively assess peritrochanteric structures including gluteus minimus/medius muscles, abductor tendons, and trochanteric bursa 2
  • Can detect tendinopathy, tendon tears, and associated bursitis that characterize GTPS 3, 4

Role of CT in GTPS

• CT is less sensitive for soft tissue evaluation compared to MRI 1
• CT may be useful in specific scenarios:
  • When fracture detection is needed and radiographs are negative or equivocal 1
  • For additional fracture characterization for treatment planning 1
  • When MRI is contraindicated 1

Key MRI Findings in GTPS

• Peritrochanteric T2 hyperintensity (edema) is commonly seen, though it can also be present in asymptomatic individuals 4, 5
• Gluteus medius/minimus tendinopathy is significantly associated with trochanteric pain (88% of symptomatic patients vs 50% of asymptomatic) 4
• MRI can detect partial or complete tears of the gluteal tendons 3, 6
• Trochanteric bursitis has a high negative predictive value (97%) for pain - absence of bursitis makes GTPS unlikely 5

Clinical Correlation

• MRI findings must be correlated with clinical symptoms as peritrochanteric abnormalities are common in asymptomatic individuals 4, 7
• The 30-second single-leg stance test (sensitivity 100%, specificity 97.3%) and resisted external derotation test (sensitivity 88%, specificity 97.3%) can help confirm clinical diagnosis when correlated with MRI findings 3

Common Pitfalls

• Peritrochanteric edema alone on MRI is not necessarily associated with pain and may be seen in asymptomatic individuals 4, 5
• Differentiation between trochanteric bursitis and gluteus medius/minimus tendinosis can be difficult, and these conditions frequently coexist 2
• In patients with hip prostheses, adverse reactions to metal debris could be misinterpreted as trochanteric bursitis 2
• Ultrasound can be considered as an alternative when MRI is contraindicated, as it can effectively detect bursitis and evaluate gluteal tendons 2