Radiologic and Pathologic Features of the Transmantle Sign in Focal Cortical Dysplasia: The T1 Signal Is Useful for...

Area of Science:

• Neuroradiology
• Neuroimaging
• Pathology

Background:

• The transmantle sign is a key MR imaging finding in focal cortical dysplasia type IIb.
• Typically hyperintense on T2WI/FLAIR and hypointense on T1WI, the transmantle sign can exhibit T1 high signal in some cases.

Purpose of the Study:

• To investigate the causes of T1 high signal within the transmantle sign.
• To correlate imaging findings with pathological features in focal cortical dysplasia.

Main Methods:

• Retrospective review of 141 patients with focal cortical dysplasia.
• Selection of 25 patients exhibiting the transmantle sign.
• Analysis of imaging (T1/T2WI, FLAIR) and histopathology (balloon cells, dysmorphic neurons, gliosis, calcifications).

Main Results:

• Nine of 25 patients (approx. 6%) showed a T1-high-signal transmantle sign, all diagnosed as focal cortical dysplasia type IIb.
• Patients with T1 high signal had a significantly higher number of balloon cells compared to those without.
• No significant differences were observed in dysmorphic neurons, gliosis, or calcifications.

Conclusions:

• The T1 high signal in the transmantle sign is strongly associated with focal cortical dysplasia type IIb.
• This finding may be attributed to a high density of balloon cells.
• The T1 high signal can assist in differentiating focal cortical dysplasia subtypes, particularly type IIb.