Hyperperfusion Tmax mapping for nonconvulsive status epilepticus in the acute setting: A pilot case-control study.

Area of Science:

• Neurology
• Radiology
• Neuroimaging

Background:

• Nonconvulsive status epilepticus (NCSE) is frequently misdiagnosed in emergency departments.
• Computed tomographic perfusion (CTP) is used in hyperacute settings to detect seizure-induced hyperperfusion, but lacks diagnostic thresholds and has high interrater variability.
• Differentiating NCSE from acute ischemic stroke in the hyperacute setting is challenging.

Purpose of the Study:

• To evaluate the diagnostic value of reverse Tmax (rTmax) mapping in differentiating NCSE from acute ischemic stroke.
• To assess the reliability and accuracy of rTmax in detecting NCSE-induced hyperperfusion.

Main Methods:

• A pilot case-control study comparing 17 NCSE patients with 17 matched stroke patients.
• CTP standard maps (MTT, CBV, CBF) and rTmax maps were analyzed by two blinded experts.
• Interrater agreement was assessed using Cronbach alpha, and accuracy was determined by receiver operating curve analysis.

Main Results:

• rTmax maps identified hyperperfusion in 11 of 17 NCSE cases, but in none of the 17 stroke cases.
• rTmax demonstrated higher intra- and interrater reliability (κ=1) compared to standard CTP maps (κ=0.6).
• rTmax achieved 82% accuracy in differentiating NCSE from stroke in the hyperacute setting, with better agreement with EEG at a sublobar level.

Conclusions:

• rTmax mapping is a potentially reliable tool for detecting NCSE-induced hyperperfusion using a reproducible, threshold-based approach.
• Further studies are required to validate rTmax for implementation in the differential diagnosis of focal neurological deficits.
• rTmax may improve the diagnostic accuracy of NCSE in hyperacute neuroimaging.