Can stones in the parotid or submandibular gland be visualized on a Magnetic Resonance Imaging (MRI) neck scan?

MRI Neck Scan for Salivary Gland Stones

Salivary gland stones (sialoliths) are not well visualized on MRI and are better detected using CT imaging, which is the preferred modality for identifying sialoliths in both parotid and submandibular glands. 1

Imaging Modalities for Salivary Gland Stones

MRI Limitations

• MRI has poor sensitivity for detecting salivary stones due to their calcium composition
• Stones appear as signal voids that may be difficult to distinguish from normal ductal structures or vascular flow voids
• Susceptibility artifacts on MRI can further complicate stone identification

Preferred Imaging Modalities for Sialoliths

• CT imaging: Superior for detecting sialoliths due to:

  • Better visualization of calcified structures
  • Higher sensitivity for detecting small stones
  • Clearer delineation of bony landmarks and erosion 1
  • No contrast needed specifically for stone detection

• Ultrasonography: Often used as first-line imaging for accessible salivary glands

  • High sensitivity (89.9%) and specificity (96.6%) for stone detection 2
  • Particularly effective for submandibular gland stones
  • Non-invasive and radiation-free
  • Limited for deep parotid lobe assessment

• Sialography: Traditional gold standard for duct visualization

  • Can show exact location of stones and duct stenoses
  • Particularly useful when planning sialoendoscopy 3
  • Contraindicated in acute infection

Clinical Implications

When to Use MRI for Salivary Gland Imaging

MRI is preferred when evaluating:

• Soft tissue masses within the gland
• Deep lobe involvement
• Perineural spread
• Relationship to surrounding structures
• Differentiating benign from malignant lesions 1, 4

Algorithm for Salivary Stone Imaging

1. Initial assessment: Ultrasound for accessible portions of glands
2. If stone suspected but not confirmed: Non-contrast CT
3. If ductal anatomy needed: Sialography (conventional or CT)
4. If soft tissue pathology is primary concern: MRI with contrast

Common Pitfalls

• Relying solely on MRI to exclude sialolithiasis can lead to missed diagnoses
• Small stones (<3mm) may be missed on standard imaging
• Multiple imaging modalities may be needed for comprehensive evaluation
• Mistaking normal anatomical structures or vascular flow voids for stones on MRI

For optimal patient outcomes, CT should be the primary imaging modality when salivary stones are suspected, with ultrasound serving as a useful initial screening tool, particularly for the submandibular gland and superficial parotid lobe.