Radiological Investigations in Tornwaldt Cyst
MRI is the best imaging modality for diagnosing Tornwaldt cyst, with characteristic high signal intensity on T1-weighted, T2-weighted, and FLAIR sequences. 1, 2, 3
Primary Imaging Recommendation
Obtain MRI of the nasopharynx/maxillofacial region without contrast as the gold standard diagnostic test for suspected Tornwaldt cyst. MRI demonstrates superior sensitivity compared to CT for detecting and characterizing these lesions 1, 2, 4.
MRI Protocol Specifications
The optimal MRI protocol should include:
- T1-weighted sequences: Tornwaldt cysts characteristically show high signal intensity compared to muscle (hyperintense) 3
- T2-weighted sequences: Cysts appear isointense to CSF 3
- FLAIR (fluid-attenuated inversion recovery): Cysts demonstrate hyperintense signal compared to gray matter 3
This characteristic imaging pattern—high signal on T1, T2, and FLAIR—is virtually diagnostic and distinguishes Tornwaldt cysts from other nasopharyngeal pathology.
When CT May Be Considered
CT is significantly less effective than MRI for detecting and characterizing Tornwaldt cysts 2. However, CT may have a limited role:
- When MRI is contraindicated or unavailable
- Detection rate: only 0.013% on CT versus 0.13% on MRI 4
- Mean cyst size detected: 0.66 cm³ on CT versus 0.58 cm³ on MRI 4
CT without contrast of the paranasal sinuses would be the appropriate protocol if CT must be used, though it will miss many smaller lesions 5.
Clinical Context for Imaging
Order imaging when patients present with:
- Persistent nasal discharge or postnasal drip
- Occipital headaches
- Nasopharyngeal obstruction symptoms
- Eustachian tube dysfunction or otitis media with effusion 1, 4, 6
- Unexplained sinonasal symptoms 7
Key Imaging Characteristics
On MRI, expect to find:
- Location: Midline posterior nasopharyngeal wall
- Shape: Round (82%) or oval (18%) 3
- Size: Mean 5.5-6.0 mm, though can be much larger when symptomatic 3
- Signal: High on T1, T2, and FLAIR—this triad is pathognomonic 3
Important Caveats
- Nasal endoscopy should precede imaging as it is the easiest way to visualize the cyst during routine examination 8
- Incidental detection rate is very low (0.06% overall, 1.9% on brain MRI studies) 4, 3
- Contrast is not necessary for diagnosis—the characteristic signal intensities on non-contrast sequences are sufficient 3
- Cysts <1-2 cm are usually asymptomatic; larger cysts are more likely to cause symptoms 1, 2