Both CT and MRI imaging scans can be read as negative in a patient with an acute stroke.
Risk factors for negative imaging studies:
(1) small infarct
(2) poor image quality
(3) interpretation error
(4) failure to perform follow-up scan after an initial negative scan
(5) failure to provide sufficient clinical information to the radiologist
(6) brainstem stroke
(7) low NIHSS score
A CT scan may be negative with:
(1) small or late-presenting subarachnoid hemorrhage
(2) ischemic stroke (versus diffusion-weighted MRI)
(3) cerebral venous sinus thrombosis
(4) lesions in the posterior fossa
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Specialty: Neurology, Emergency Medicine
