Neuroradiology and Neurodiagnostics
Core concepts
Understand the modality choices: CT for acute hemorrhage and trauma, MRI for soft tissue and ischemia, CT angiography for vascular lesions, and catheter angiography for definitive vascular evaluation. Know the imaging signatures of common lesions: epidural and subdural hematomas, subarachnoid hemorrhage, ischemic stroke (restricted diffusion on DWI), tumors, and hydrocephalus. Understand the value of TCDs for vasospasm monitoring, EEG for seizures and encephalopathy, and EMG/NCS for peripheral nerve disease. Know the basics of contrast safety and the limitations of each modality.
Traps
A frequent trap is relying on a noncontrast CT to exclude early ischemia - CT may be normal early, and DWI is more sensitive. Another is missing a posterior fossa lesion because of artifact or incomplete imaging. Questions may test that TCDs are supportive but not definitive for vasospasm. Watch for interpreting a normal EEG as excluding seizures (deep foci may be missed).
Worked rule of thumb
Acute stroke: noncontrast CT first to exclude hemorrhage, then vascular imaging; DWI confirms ischemia. For suspected vasospasm, TCDs guide but angiography is definitive. For peripheral nerve lesions, EMG/NCS localizes and grades severity.