What is the preferred imaging modality, CT (Computed Tomography) or MRI (Magnetic Resonance Imaging), for ruling out a tumor or syringomyelia?

MRI is the Preferred Imaging Modality for Ruling Out Tumor or Syringomyelia

MRI is the preferred imaging modality for ruling out tumor or syringomyelia due to its high sensitivity and specificity for detecting these pathologies. 1

Rationale for MRI as First Choice

• MRI provides superior soft tissue contrast compared to CT, making it possible to better visualize the relationship of tumors to soft tissues, bone marrow, and neural structures 1
• MRI has demonstrated high sensitivity and specificity for detecting pathologies including syringomyelia and spinal dysraphism 1
• MRI is considered the best imaging method to evaluate syringomyelia, allowing visualization from the posterior cranial fossa to the sacro-lumbar region 2
• For spine lesions, MRI has been shown to be the most sensitive modality for detection of tumors, followed by FDG-PET/CT and CT 1

Protocol Considerations for MRI

For Syringomyelia Detection:

• Complete spine MRI without IV contrast is typically sufficient for initial evaluation 1
• Sagittal and axial spin echo T1 and fast spin echo T2 weighted images are essential 2
• Coronal views may be particularly important when the patient presents with scoliosis 2
• The entire spinal cord should be studied using phased-array coils for optimal visualization 2

For Tumor Detection:

• MRI without and with IV contrast is recommended for suspected neoplasms 1
• Precontrast images are necessary to accurately assess enhancement after contrast administration 1
• Contrast enhancement helps differentiate between syringomyelia, syringomyelia associated with tumor, and cystic tumors 3

Limitations of CT for These Conditions

• There is no relevant literature to support the use of CT spine in initial imaging evaluation for detecting syringomyelia 1
• While CT better defines destruction of cortical bone, it is suboptimal for evaluating intraspinal contents and paraspinal soft tissues compared to MRI 1
• CT myelography, historically used for intraspinal pathologies, has decreased in usefulness with the advent of MRI 1
• In spine lesions specifically, CT has been shown to be less sensitive than MRI for tumor detection 1

Special Considerations

• For pediatric patients with suspected syringomyelia, MRI is particularly important as it can also identify associated conditions such as tethered cord syndrome, low-lying conus medullaris, or fatty filum terminale 1
• In cases where MRI is contraindicated (e.g., certain implants, severe claustrophobia), CT with contrast may be considered as an alternative, though with recognized limitations 1
• For patients with suspected tumor, gadolinium contrast enhancement significantly improves diagnostic accuracy by enabling clear demarcation of neoplastic tissue from syrinx or cyst 3

Monitoring and Follow-up

• MRI is also useful for post-operative follow-up to evaluate the persistence of medullary cysts and structural changes 2
• Advanced MRI techniques such as diffusion-weighted imaging and dynamic contrast-enhanced perfusion may provide additional information for characterizing soft tissue tumors 4